WorldWideScience

Sample records for underwater sound radiated

  1. Simulation and Characteristics Analysis on Vibration and Sound Radiation Response for a Small Underwater Robot

    Directory of Open Access Journals (Sweden)

    Zhou Zhi

    2016-01-01

    Full Text Available An underwater robot is one of the important ocean equipment, and especially its stealth performance has influenced on the vitality in naval warfare. Structure radiation noise as the main source of underwater robot noise, so analysis on vibration and noise radiation is a topic of great concern. The way is used widely that based on fluid-solid coupling modal analysis combined with simulation on vibration and noise-radiation response in order to evaluate stealth performance of underwater structure. In the paper, firstly via finite element method and boundary element method, the modal frequencies and vibration modes of small underwater robot are calculated. Then the surface vibration displacements of underwater robot and the sound pressures of acoustic field under different frequency horizontal exciting force are obtained and analyzed. Lastly, through the analysis of the structural vibration and acoustic performance, the control strategies for structure bending vibration, acoustic radiation and structural acoustic design are proposed.

  2. Underwater Sound Reference Division

    Data.gov (United States)

    Federal Laboratory Consortium — The Underwater Sound Reference Division (USRD) serves as the U.S. standardizing activity in the area of underwater acoustic measurements, as the National Institute...

  3. Experimental Assessment of Underwater Radiated Sound of Different Ship Types

    NARCIS (Netherlands)

    Jansen, H.W.; Jong, C.A.F. de

    2015-01-01

    The aim of the SONIC project is to develop tools to investigate and mitigate the effects of underwater noise generated by shipping. One way to study the contribution of shipping noise to the background noise in the seas is to produce shipping noise maps. The SONIC project delivers the required

  4. Underwater sound radiation from an elastically coated plate with an embedded and distributed inhomogeneity.

    Science.gov (United States)

    Zhang, Yanni; Pan, Jie

    2015-05-01

    This paper studies the effects of an embedded and distributed inhomogeneity on the underwater sound radiation from an elastically coated plate. Embedding a signal conditioning plate (SCP) in the coating material provides an extra parameter for controlling the sound radiation of the plate, as compared with the previous design with an SCP on the coating surface [Y. Zhang and J. Pan, J. Acoust. Soc. Am. 133(1), 173-185 (2013)]. For such a configuration, the vibration and sound responses of the coated plate to a point force excitation are described by three coupled Fredholm integral equations of the second kind. Its acoustical properties are examined by comparing the radiation powers from plates without an SCP, with a surface SCP, and with an embedded SCP. The differences in the sound powers are explained through resonance and scattering caused by the interaction of the embedded SCP with structural waves. The effects of the depth of the embedded SCP in the coating material on the sound radiation properties of the plate are discussed in detail.

  5. Underwater sound radiation from an elastically coated plate with a discontinuity introduced by a signal conditioning plate.

    Science.gov (United States)

    Zhang, Yanni; Pan, Jie

    2013-01-01

    Underwater structural sound radiation and reflection can be reduced by adding an elastic coating to a structure. To increase the signal-to-noise ratio of a detecting hydrophone placed in front of the coating, a signal conditioning plate (SCP) of finite size placed between the coating and the hydrophone is proposed to increase the local reflection of incoming sound. This paper studies the effects of a SCP as a distributed discontinuity on the general properties of the sound radiation of a coated plate. The discontinuity introduced by the SCP changes the vibration and radiated sound power of the coated plate by scattering and reflecting structural waves in the coating. The trapped modal response of the structural waves is also observed and found to be responsible for the increase of sound and vibration of the plate at the corresponding resonance frequencies.

  6. Underwater Sound Propagation from Marine Pile Driving.

    Science.gov (United States)

    Reyff, James A

    2016-01-01

    Pile driving occurs in a variety of nearshore environments that typically have very shallow-water depths. The propagation of pile-driving sound in water is complex, where sound is directly radiated from the pile as well as through the ground substrate. Piles driven in the ground near water bodies can produce considerable underwater sound energy. This paper presents examples of sound propagation through shallow-water environments. Some of these examples illustrate the substantial variation in sound amplitude over time that can be critical to understand when computing an acoustic-based safety zone for aquatic species.

  7. Calibration of Underwater Sound Transducers

    OpenAIRE

    H.R.S. Sastry

    1983-01-01

    The techniques of calibration of underwater sound transducers for farfield, near-field and closed environment conditions are reviewed in this paper .The design of acoustic calibration tank is mentioned. The facilities available at Naval Physical & Oceanographic Laboratory, Cochin for calibration of transducers are also listed.

  8. WODA technical guidance on underwater sound from dredging

    NARCIS (Netherlands)

    Thomsen, F.; Borsani, F.; Clarke, D.; Jong, C. de; Wit, P. de; Goethals, F.; Holtkamp, M.; Martin, E.S.; Spadaro, P.; Raalte, G. van; Victor, G.Y.V.; Jensen, A.

    2016-01-01

    The World Organization of Dredging Associations (WODA) has identified underwater sound as an environmental issue that needs further consideration. A WODA Expert Group on Underwater Sound (WEGUS) prepared a guidance paper in 2013 on dredging sound, including a summary of potential impacts on aquatic

  9. The WODA guidance paper on underwater sound from dredging (abstract)

    NARCIS (Netherlands)

    Thomsen, F.; Borsani, F.; Clarke, D.; Jong, C.A.F. de; Witt, P. de; Holtkamp, M.; Goethals, F.; San Martin, E.; Spadaro, P.; Raalte, G. van; Jensen, A.

    2013-01-01

    The World Organisation of Dredging Associations (WODA) has identified underwater sound as an environmental issue that needs further consideration. A WODA Expert Group on Underwater Sound (WEGUS) was established to provide a guidance paper on dredging sound, impact on aquatic biota and advice on

  10. Design and implementation of an underwater sound recording device

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Jayson J.; Myers, Joshua R.; Carlson, Thomas J.; Deng, Zhiqun; Rohrer, John S.; Caviggia, Kurt A.

    2011-09-19

    The purpose of this study was to design and build two versions of an underwater sound recording device. The device designed is referred to as the Underwater Sound Recorder (USR), which can be connected to one or two hydrophones or other underwater sound sensors. The URS contains a 26 dB preamplifier and a user selectable gain that permits additional amplification of input to the system from 26 dB to 46 dB. Signals within the frequency range up to 15 kHz may be recorded using the USR. Examples of USR applications are monitoring underwater processes that have the potential to create large pressure waves that could potentially harm fish or other aquatic life, such as underwater explosions or pile driving. Additional applications are recording sound generated by vessels or the vocalizations of some marine mammals, such as the calls from many species of whales.

  11. Transducers and arrays for underwater sound

    CERN Document Server

    Butler, John L

    2016-01-01

    This improved and updated second edition covers the theory, development, and design of electro-acoustic transducers for underwater applications. This highly regarded text discusses the basics of piezoelectric and magnetostrictive transducers that are currently being used as well as promising new designs. It presents the basic acoustics as well as the specific acoustics data needed in transducer design and evaluation. A broad range of designs of projectors and hydrophones are described in detail along with methods of modeling, evaluation, and measurement. Analysis of projector and hydrophone transducer arrays, including the effects of mutual radiation impedance and numerical models for elements and arrays, are also covered. The book includes new advances in transducer design and transducer materials and has been completely reorganized to be suitable for use as a textbook, as well as a reference or handbook. The new edition contains updates to the first edition, end-of-chapter exercises, and solutions to select...

  12. Underwater and in-air sounds from a small hovercraft

    Science.gov (United States)

    Blackwell, Susanna B.; Greene, Charles R.

    2005-12-01

    Underwater and in-air recordings were made from a boat anchored near Prudhoe Bay, Alaska, while a Griffon 2000TD hovercraft drove by at or near full power on four passes. At the closest point of approach (CPA, 6.5 m), underwater broadband (10-10 000 Hz) levels reached 133 and 131 dB re: 1 μPa at depths of 1 and 7 m, respectively. In-air unweighted and A-weighted broadband (10-10 000 Hz) levels reached 104 and 97 dB re: 20 μPa, respectively. The hovercraft produced sound at a wide range of frequencies. Both underwater and in air, the largest spectral peak was near 87 Hz, which corresponded to the blade rate of the thrust propeller. In addition, the spectral composition included several harmonics of this frequency. The shaft or blade rate of the lift fan was barely detectable underwater despite its proximity to the water. The hovercraft was considerably quieter underwater than similar-sized conventional vessels and may be an attractive alternative when there is concern over underwater sounds.

  13. Underwater radiated noise from modern commercial ships.

    Science.gov (United States)

    McKenna, Megan F; Ross, Donald; Wiggins, Sean M; Hildebrand, John A

    2012-01-01

    Underwater radiated noise measurements for seven types of modern commercial ships during normal operating conditions are presented. Calibrated acoustic data (autonomous seafloor-mounted acoustic recorder were combined with ship passage information from the Automatic Identification System. This approach allowed for detailed measurements (i.e., source level, sound exposure level, and transmission range) on ships of opportunity. A key result was different acoustic levels and spectral shapes observed from different ship-types. A 54 kGT container ship had the highest broadband source level at 188 dB re 1 μPa@1m; a 26 kGT chemical tanker had the lowest at 177 dB re 1 μPa@1m. Bulk carriers had higher source levels near 100 Hz, while container ship and tanker noise was predominantly below 40 Hz. Simple models to predict source levels of modern merchant ships as a group from particular ship characteristics (e.g., length, gross tonnage, and speed) were not possible given individual ship-type differences. Furthermore, ship noise was observed to radiate asymmetrically. Stern aspect noise levels are 5 to 10 dB higher than bow aspect noise levels. Collectively, these results emphasize the importance of including modern ship-types in quantifying shipping noise for predictive models of global, regional, and local marine environments. © 2012 Acoustical Society of America.

  14. Underwater sound produced by individual drop impacts and rainfall

    DEFF Research Database (Denmark)

    Pumphrey, Hugh C.; Crum, L. A.; Jensen, Leif Bjørnø

    1989-01-01

    ; the second occurs for some impacts but not others. A range of conditions is described in which a bubble is produced for every drop impact, and it is shown that these conditions are likely to be met by a significant fraction of the raindrops in a typical shower. Underwater sound produced by artificial as well...

  15. Sources of underwater sound and their characterisation (abstract)

    NARCIS (Netherlands)

    Ainslie, M.A.; Jong, C.A.F. de

    2013-01-01

    After centuries of speculation, punctuated by occasional theoretical or experimental advances, the first intensive research into underwater sound took place 100 years ago, applied initially to provide advance warning of icebergs after the loss of RMS Titanic in 1912, and later to counter the U-boat

  16. Design and implementation of an underwater sound recording device.

    Science.gov (United States)

    Martinez, Jayson J; Myers, Josh R; Carlson, Thomas J; Deng, Z Daniel; Rohrer, John S; Caviggia, Kurt A; Woodley, Christa M; Weiland, Mark A

    2011-01-01

    To monitor the underwater sound and pressure waves generated by anthropogenic activities such as underwater blasting and pile driving, an autonomous system was designed to record underwater acoustic signals. The underwater sound recording device (USR) allows for connections of two hydrophones or other dynamic pressure sensors, filters high frequency noise out of the collected signals, has a gain that can be independently set for each sensor, and allows for 2 h of data collection. Two versions of the USR were created: a submersible model deployable to a maximum depth of 300 m, and a watertight but not fully submersible model. Tests were performed on the USR in the laboratory using a data acquisition system to send single-frequency sinusoidal voltages directly to each component. These tests verified that the device operates as designed and performs as well as larger commercially available data acquisition systems, which are not suited for field use. On average, the designed gain values differed from the actual measured gain values by about 0.35 dB. A prototype of the device was used in a case study to measure blast pressures while investigating the effect of underwater rock blasting on juvenile Chinook salmon and rainbow trout. In the case study, maximum positive pressure from the blast was found to be significantly correlated with frequency of injury for individual fish. The case study also demonstrated that the device withstood operation in harsh environments, making it a valuable tool for collecting field measurements.

  17. Design and Implementation of an Underwater Sound Recording Device

    Directory of Open Access Journals (Sweden)

    Christa M. Woodley

    2011-09-01

    Full Text Available To monitor the underwater sound and pressure waves generated by anthropogenic activities such as underwater blasting and pile driving, an autonomous system was designed to record underwater acoustic signals. The underwater sound recording device (USR allows for connections of two hydrophones or other dynamic pressure sensors, filters high frequency noise out of the collected signals, has a gain that can be independently set for each sensor, and allows for 2 h of data collection. Two versions of the USR were created: a submersible model deployable to a maximum depth of 300 m, and a watertight but not fully submersible model. Tests were performed on the USR in the laboratory using a data acquisition system to send single-frequency sinusoidal voltages directly to each component. These tests verified that the device operates as designed and performs as well as larger commercially available data acquisition systems, which are not suited for field use. On average, the designed gain values differed from the actual measured gain values by about 0.35 dB. A prototype of the device was used in a case study to measure blast pressures while investigating the effect of underwater rock blasting on juvenile Chinook salmon and rainbow trout. In the case study, maximum positive pressure from the blast was found to be significantly correlated with frequency of injury for individual fish. The case study also demonstrated that the device withstood operation in harsh environments, making it a valuable tool for collecting field measurements.

  18. Broadband focusing of underwater sound using a transparent pentamode lens.

    Science.gov (United States)

    Su, Xiaoshi; Norris, Andrew N; Cushing, Colby W; Haberman, Michael R; Wilson, Preston S

    2017-06-01

    An inhomogeneous acoustic metamaterial lens based on spatial variation of refractive index for broadband focusing of underwater sound is reported. The index gradient follows a modified hyperbolic secant profile designed to reduce aberration and suppress side lobes. The gradient index (GRIN) lens is comprised of transversely isotropic hexagonal microstructures with tunable quasi-static bulk modulus and mass density. In addition, the unit cells are impedance-matched to water and have in-plane shear modulus negligible compared to the effective bulk modulus. The flat GRIN lens is fabricated by cutting hexagonal centimeter scale hollow microstructures in aluminum plates, which are then stacked and sealed from the exterior water. Broadband focusing effects are observed within the homogenization regime of the lattice in both finite element simulations and underwater measurements (20-40 kHz). This design approach has potential applications in medical ultrasound imaging and underwater acoustic communications.

  19. Sources of underwater sound and their characterization

    NARCIS (Netherlands)

    Ainslie, M.A.; Jong, C.A.F. de

    2016-01-01

    Because of the history of sonar and sonar engineering, the concept of “source level” is widely used to characterize anthropogenic sound sources, but is it useful for sources other than sonar transmitters? The concept and applicability of source level are reviewed for sonar, air guns, explosions,

  20. Mapping Underwater Sound in the Dutch Part of the North Sea.

    Science.gov (United States)

    Sertlek, H Özkan; Aarts, Geert; Brasseur, Sophie; Slabbekoorn, Hans; ten Cate, Carel; von Benda-Beckmann, Alexander M; Ainslie, Michael A

    2016-01-01

    The European Union requires member states to achieve or maintain good environmental status for their marine territorial waters and explicitly mentions potentially adverse effects of underwater sound. In this study, we focused on producing maps of underwater sound from various natural and anthropogenic origins in the Dutch North Sea. The source properties and sound propagation are simulated by mathematical methods. These maps could be used to assess and predict large-scale effects on behavior and distribution of underwater marine life and therefore become a valuable tool in assessing and managing the impact of underwater sound on marine life.

  1. Acoustically sticky topographic metasurfaces for underwater sound absorption.

    Science.gov (United States)

    Lee, Hunki; Jung, Myungki; Kim, Minsoo; Shin, Ryung; Kang, Shinill; Ohm, Won-Suk; Kim, Yong Tae

    2018-03-01

    A class of metasurfaces for underwater sound absorption, based on a design principle that maximizes thermoviscous loss, is presented. When a sound meets a solid surface, it leaves a footprint in the form of thermoviscous boundary layers in which energy loss takes place. Considered to be a nuisance, this acoustic to vorticity/entropy mode conversion and the subsequent loss are often ignored in the existing designs of acoustic metamaterials and metasurfaces. The metasurface created is made of a series of topographic meta-atoms, i.e., intaglios and reliefs engraved directly on the solid object to be concealed. The metasurface is acoustically sticky in that it rather facilitates the conversion of the incident sound to vorticity and entropy modes, hence the thermoviscous loss, leading to the desired anechoic property. A prototype metasurface machined on a brass object is tested for its anechoicity, and shows a multitude of absorption peaks as large as unity in the 2-5 MHz range. Computations also indicate that a topographic metasurface is robust to hydrostatic pressure variation, a quality much sought-after in underwater applications.

  2. The low-frequency sound power measuring technique for an underwater source in a non-anechoic tank

    Science.gov (United States)

    Zhang, Yi-Ming; Tang, Rui; Li, Qi; Shang, Da-Jing

    2018-03-01

    In order to determine the radiated sound power of an underwater source below the Schroeder cut-off frequency in a non-anechoic tank, a low-frequency extension measuring technique is proposed. This technique is based on a unique relationship between the transmission characteristics of the enclosed field and those of the free field, which can be obtained as a correction term based on previous measurements of a known simple source. The radiated sound power of an unknown underwater source in the free field can thereby be obtained accurately from measurements in a non-anechoic tank. To verify the validity of the proposed technique, a mathematical model of the enclosed field is established using normal-mode theory, and the relationship between the transmission characteristics of the enclosed and free fields is obtained. The radiated sound power of an underwater transducer source is tested in a glass tank using the proposed low-frequency extension measuring technique. Compared with the free field, the radiated sound power level of the narrowband spectrum deviation is found to be less than 3 dB, and the 1/3 octave spectrum deviation is found to be less than 1 dB. The proposed testing technique can be used not only to extend the low-frequency applications of non-anechoic tanks, but also for measurement of radiated sound power from complicated sources in non-anechoic tanks.

  3. Mapping underwater sound in the dutch part of the North Sea

    NARCIS (Netherlands)

    Özkan Sertlek, H.; Aarts, Geert; Brasseur, Sophie; Slabbekoorn, Hans; Cate, ten Carel; Benda-Beckmann, von Alexander M.; Ainslie, Michael A.

    2016-01-01

    The European Union requires member states to achieve or maintain good environmental status for their marine territorial waters and explicitly mentions potentially adverse effects of underwater sound. In this study, we focused on producing maps of underwater sound from various natural and

  4. Mapping underwater sound in the Dutch part of the North Sea

    NARCIS (Netherlands)

    Sertlek, H.O.; Aarts, G.; Brasseur, S.; Slabbekoorn, H.; Cate, C. ten; Benda-Beckmann, A.M. von; Ainslie, M.A.

    2016-01-01

    The European Union requires member states to achieve or maintain good environmental status for their marine territorial waters and explicitly mentions potentially adverse effects of underwater sound. In this study, we focused on producing maps of underwater sound from various natural and

  5. Thin Fresnel zone plate lenses for focusing underwater sound

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, David C., E-mail: david.calvo@nrl.navy.mil; Thangawng, Abel L.; Nicholas, Michael; Layman, Christopher N. [Acoustics Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2015-07-06

    A Fresnel zone plate (FZP) lens of the Soret type creates a focus by constructive interference of waves diffracted through open annular zones in an opaque screen. For underwater sound below MHz frequencies, a large FZP that blocks sound using high-impedance, dense materials would have practical disadvantages. We experimentally and numerically investigate an alternative approach of creating a FZP with thin (0.4λ) acoustically opaque zones made of soft silicone rubber foam attached to a thin (0.1λ) transparent rubber substrate. An ultra-thin (0.0068λ) FZP that achieves higher gain is also proposed and simulated which uses low-volume fraction, bubble-like resonant air ring cavities to construct opaque zones. Laboratory measurements at 200 kHz indicate that the rubber foam can be accurately modeled as a lossy fluid with an acoustic impedance approximately 1/10 that of water. Measured focal gains up to 20 dB agree with theoretical predictions for normal and oblique incidence. The measured focal radius of 0.68λ (peak-to-null) agrees with the Rayleigh diffraction limit prediction of 0.61 λ/NA (NA = 0.88) for a low-aberration lens.

  6. Thin Fresnel zone plate lenses for focusing underwater sound

    Science.gov (United States)

    Calvo, David C.; Thangawng, Abel L.; Nicholas, Michael; Layman, Christopher N.

    2015-07-01

    A Fresnel zone plate (FZP) lens of the Soret type creates a focus by constructive interference of waves diffracted through open annular zones in an opaque screen. For underwater sound below MHz frequencies, a large FZP that blocks sound using high-impedance, dense materials would have practical disadvantages. We experimentally and numerically investigate an alternative approach of creating a FZP with thin (0.4λ) acoustically opaque zones made of soft silicone rubber foam attached to a thin (0.1λ) transparent rubber substrate. An ultra-thin (0.0068λ) FZP that achieves higher gain is also proposed and simulated which uses low-volume fraction, bubble-like resonant air ring cavities to construct opaque zones. Laboratory measurements at 200 kHz indicate that the rubber foam can be accurately modeled as a lossy fluid with an acoustic impedance approximately 1/10 that of water. Measured focal gains up to 20 dB agree with theoretical predictions for normal and oblique incidence. The measured focal radius of 0.68λ (peak-to-null) agrees with the Rayleigh diffraction limit prediction of 0.61 λ/NA (NA = 0.88) for a low-aberration lens.

  7. Thin Fresnel zone plate lenses for focusing underwater sound

    International Nuclear Information System (INIS)

    Calvo, David C.; Thangawng, Abel L.; Nicholas, Michael; Layman, Christopher N.

    2015-01-01

    A Fresnel zone plate (FZP) lens of the Soret type creates a focus by constructive interference of waves diffracted through open annular zones in an opaque screen. For underwater sound below MHz frequencies, a large FZP that blocks sound using high-impedance, dense materials would have practical disadvantages. We experimentally and numerically investigate an alternative approach of creating a FZP with thin (0.4λ) acoustically opaque zones made of soft silicone rubber foam attached to a thin (0.1λ) transparent rubber substrate. An ultra-thin (0.0068λ) FZP that achieves higher gain is also proposed and simulated which uses low-volume fraction, bubble-like resonant air ring cavities to construct opaque zones. Laboratory measurements at 200 kHz indicate that the rubber foam can be accurately modeled as a lossy fluid with an acoustic impedance approximately 1/10 that of water. Measured focal gains up to 20 dB agree with theoretical predictions for normal and oblique incidence. The measured focal radius of 0.68λ (peak-to-null) agrees with the Rayleigh diffraction limit prediction of 0.61 λ/NA (NA = 0.88) for a low-aberration lens

  8. Aquatic Acoustic Metrics Interface Utility for Underwater Sound Monitoring and Analysis

    Science.gov (United States)

    Ren, Huiying; Halvorsen, Michele B.; Deng, Zhiqun Daniel; Carlson, Thomas J.

    2012-01-01

    Fishes and marine mammals may suffer a range of potential effects from exposure to intense underwater sound generated by anthropogenic activities such as pile driving, shipping, sonars, and underwater blasting. Several underwater sound recording (USR) devices have been built to acquire samples of the underwater sound generated by anthropogenic activities. Software becomes indispensable for processing and analyzing the audio files recorded by these USRs. In this paper, we provide a detailed description of a new software package, the Aquatic Acoustic Metrics Interface (AAMI), specifically designed for analysis of underwater sound recordings to provide data in metrics that facilitate evaluation of the potential impacts of the sound on aquatic animals. In addition to the basic functions, such as loading and editing audio files recorded by USRs and batch processing of sound files, the software utilizes recording system calibration data to compute important parameters in physical units. The software also facilitates comparison of the noise sound sample metrics with biological measures such as audiograms of the sensitivity of aquatic animals to the sound, integrating various components into a single analytical frame. The features of the AAMI software are discussed, and several case studies are presented to illustrate its functionality. PMID:22969353

  9. Aquatic Acoustic Metrics Interface Utility for Underwater Sound Monitoring and Analysis

    Directory of Open Access Journals (Sweden)

    Thomas J. Carlson

    2012-05-01

    Full Text Available Fishes and marine mammals may suffer a range of potential effects from exposure to intense underwater sound generated by anthropogenic activities such as pile driving, shipping, sonars, and underwater blasting. Several underwater sound recording (USR devices have been built to acquire samples of the underwater sound generated by anthropogenic activities. Software becomes indispensable for processing and analyzing the audio files recorded by these USRs. In this paper, we provide a detailed description of a new software package, the Aquatic Acoustic Metrics Interface (AAMI, specifically designed for analysis of underwater sound recordings to provide data in metrics that facilitate evaluation of the potential impacts of the sound on aquatic animals. In addition to the basic functions, such as loading and editing audio files recorded by USRs and batch processing of sound files, the software utilizes recording system calibration data to compute important parameters in physical units. The software also facilitates comparison of the noise sound sample metrics with biological measures such as audiograms of the sensitivity of aquatic animals to the sound, integrating various components into a single analytical frame. The features of the AAMI software are discussed, and several case studies are presented to illustrate its functionality.

  10. Properties of sound attenuation around a two-dimensional underwater vehicle with a large cavitation number

    International Nuclear Information System (INIS)

    Ye Peng-Cheng; Pan Guang

    2015-01-01

    Due to the high speed of underwater vehicles, cavitation is generated inevitably along with the sound attenuation when the sound signal traverses through the cavity region around the underwater vehicle. The linear wave propagation is studied to obtain the influence of bubbly liquid on the acoustic wave propagation in the cavity region. The sound attenuation coefficient and the sound speed formula of the bubbly liquid are presented. Based on the sound attenuation coefficients with various vapor volume fractions, the attenuation of sound intensity is calculated under large cavitation number conditions. The result shows that the sound intensity attenuation is fairly small in a certain condition. Consequently, the intensity attenuation can be neglected in engineering. (paper)

  11. Radiation protection experience for divers working underwater in radiation areas

    International Nuclear Information System (INIS)

    Vallance, Charles A.; Barritt, Scott W.; White, Mark; Martinson, Steven R.

    2005-01-01

    Divers work in areas where radiological exposures would be prohibitive or even fatal to workers in dry conditions. To perform such work safely, while minimizing exposure, requires special equipment and techniques. This paper will provide an overview of the latest procedures and equipment necessary to perform work underwater in high radiation areas while meeting ALARA goals. Recent projects performed in spent fuel storage pools and inside primary containment at commercial nuclear power plants will be described to demonstrate the use of procedures and techniques for ALARA planning, personnel dose minimization, project execution, dose tracking, and control of radioactive waste

  12. Captive Bottlenose Dolphins Do Discriminate Human-Made Sounds Both Underwater and in the Air

    Science.gov (United States)

    Lima, Alice; Sébilleau, Mélissa; Boye, Martin; Durand, Candice; Hausberger, Martine; Lemasson, Alban

    2018-01-01

    Bottlenose dolphins (Tursiops truncatus) spontaneously emit individual acoustic signals that identify them to group members. We tested whether these cetaceans could learn artificial individual sound cues played underwater and whether they would generalize this learning to airborne sounds. Dolphins are thought to perceive only underwater sounds and their training depends largely on visual signals. We investigated the behavioral responses of seven dolphins in a group to learned human-made individual sound cues, played underwater and in the air. Dolphins recognized their own sound cue after hearing it underwater as they immediately moved toward the source, whereas when it was airborne they gazed more at the source of their own sound cue but did not approach it. We hypothesize that they perhaps detected modifications of the sound induced by air or were confused by the novelty of the situation, but nevertheless recognized they were being “targeted.” They did not respond when hearing another group member’s cue in either situation. This study provides further evidence that dolphins respond to individual-specific sounds and that these marine mammals possess some capacity for processing airborne acoustic signals. PMID:29445350

  13. Topological phononic states of underwater sound based on coupled ring resonators

    Energy Technology Data Exchange (ETDEWEB)

    He, Cheng; Li, Zheng; Ni, Xu; Sun, Xiao-Chen; Yu, Si-Yuan [National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, Nanjing University, Nanjing 210093 (China); Lu, Ming-Hui, E-mail: luminghui@nju.edu.cn; Liu, Xiao-Ping; Chen, Yan-Feng [National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, Nanjing University, Nanjing 210093 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2016-01-18

    We report a design of topological phononic states for underwater sound using arrays of acoustic coupled ring resonators. In each individual ring resonator, two degenerate acoustic modes, corresponding to clockwise and counter-clockwise propagation, are treated as opposite pseudospins. The gapless edge states arise in the bandgap resulting in protected pseudospin-dependent sound transportation, which is a phononic analogue of the quantum spin Hall effect. We also investigate the robustness of the topological sound state, suggesting that the observed pseudospin-dependent sound transportation remains unless the introduced defects facilitate coupling between the clockwise and counter-clockwise modes (in other words, the original mode degeneracy is broken). The topological engineering of sound transportation will certainly promise unique design for next generation of acoustic devices in sound guiding and switching, especially for underwater acoustic devices.

  14. Passive, broadband suppression of radiation of low-frequency sound.

    Science.gov (United States)

    Godin, Oleg A; Baynes, Alexander B

    2018-02-01

    Anthropogenic noise pollution of the ocean is an acute and growing problem. This letter explores one possible mechanism of noise abatement. The far-field acoustic pressure due to a compact underwater source can be suppressed by placing a small compliant body in the vicinity of the source. Here, the feasibility and efficiency of the suppression are evaluated by quantifying the reduction in radiated acoustic energy for several simple geometries, which include sound sources in an unbounded fluid, near a reflecting boundary, or in a shallow-water waveguide. The analysis is streamlined using analytic solutions for sound diffraction by simple shapes.

  15. Behavioural Response Thresholds in New Zealand Crab Megalopae to Ambient Underwater Sound

    Science.gov (United States)

    Stanley, Jenni A.; Radford, Craig A.; Jeffs, Andrew G.

    2011-01-01

    A small number of studies have demonstrated that settlement stage decapod crustaceans are able to detect and exhibit swimming, settlement and metamorphosis responses to ambient underwater sound emanating from coastal reefs. However, the intensity of the acoustic cue required to initiate the settlement and metamorphosis response, and therefore the potential range over which this acoustic cue may operate, is not known. The current study determined the behavioural response thresholds of four species of New Zealand brachyuran crab megalopae by exposing them to different intensity levels of broadcast reef sound recorded from their preferred settlement habitat and from an unfavourable settlement habitat. Megalopae of the rocky-reef crab, Leptograpsus variegatus, exhibited the lowest behavioural response threshold (highest sensitivity), with a significant reduction in time to metamorphosis (TTM) when exposed to underwater reef sound with an intensity of 90 dB re 1 µPa and greater (100, 126 and 135 dB re 1 µPa). Megalopae of the mud crab, Austrohelice crassa, which settle in soft sediment habitats, exhibited no response to any of the underwater reef sound levels. All reef associated species exposed to sound levels from an unfavourable settlement habitat showed no significant change in TTM, even at intensities that were similar to their preferred reef sound for which reductions in TTM were observed. These results indicated that megalopae were able to discern and respond selectively to habitat-specific acoustic cues. The settlement and metamorphosis behavioural response thresholds to levels of underwater reef sound determined in the current study of four species of crabs, enables preliminary estimation of the spatial range at which an acoustic settlement cue may be operating, from 5 m to 40 km depending on the species. Overall, these results indicate that underwater sound is likely to play a major role in influencing the spatial patterns of settlement of coastal crab

  16. The influence of underwater data transmission sounds on the displacement behaviour of captive harbour seals (Phoca vitulina)

    NARCIS (Netherlands)

    Kastelein, R.A.; Heul, S. van der; Verboom, W.C.; Triesscheijn, R.J.V.; Jennings, N.V.

    2006-01-01

    To prevent grounding of ships and collisions between ships in shallow coastal waters, an underwater data collection and communication network (ACME) using underwater sounds to encode and transmit data is currently under development. Marine mammals might be affected by ACME sounds since they may use

  17. Effects of locally resonant modes on underwater sound absorption in viscoelastic materials.

    Science.gov (United States)

    Wen, Jihong; Zhao, Honggang; Lv, Linmei; Yuan, Bo; Wang, Gang; Wen, Xisen

    2011-09-01

    Recently, by introducing locally resonant scatterers with spherical shape proposed in phononic crystals into design of underwater sound absorption materials, the low-frequency underwater sound absorption phenomenon induced by the localized resonances is observed. To reveal this absorption mechanism, the effect of the locally resonant mode on underwater sound absorption should be studied. In this paper, the finite element method, which is testified efficiently by comparing the calculation results with those of the layer multiple scattering method, is introduced to investigate the dynamic modes and the corresponding sound absorption of localized resonance. The relationship between the resonance modes described with the displacement contours of one unit cell and the corresponding absorption spectra is discussed in detail, which shows that the localized resonance leads to the absorption peak, and the mode conversion from longitudinal to transverse waves at the second absorption peak is more efficient than that at the first one. Finally, to show the modeling capability of FEM and investigate shape effects of locally resonant scatterers on underwater sound absorption, the absorption properties of viscoelastic materials containing locally resonant scatterers with ellipsoidal shape are discussed. © 2011 Acoustical Society of America

  18. Underwater sound due to a subsea high speed turbo compressor

    NARCIS (Netherlands)

    Binnerts, B.; Benda-Beckmann, A.M. von; Beek, P.J.G. van

    2014-01-01

    In the oil & gas industry there is a trend towards more subsea activities. To improve gas recovery from existing and new fields at greater depths, the produced gas will be compressed, processed and transported via subsea templates and underwater networks (pipelines, flexible risers, etc.). Besides

  19. Underwater sound scattering and absorption by a coated infinite plate with a distributed inhomogeneity.

    Science.gov (United States)

    Zhang, Yanni; Pan, Jie

    2013-04-01

    This paper concerns itself with the scattering and absorption of underwater incident sound by a coated infinite plate with an attached distributed inhomogeneity. Its objective is to determine if the distributed inhomogeneity can provide additional local reflection, such that it only increases the signal-to-noise ratio for a hydrophone detector placed on the inhomogeneity without significantly decreasing the overall sound absorption of the coated plate.

  20. Underwater sounds near a fuel receiving facility in western Hong Kong: relevance to dolphins.

    Science.gov (United States)

    Würsig, B; Greene, C R

    2002-08-01

    1 microPa2/Hz) and decreased with increasing frequency and distance. At distances greater than about 500 m, AFRF-associated sounds were negligible, masked by the generally high noise level of the area and attenuated by poor transmission in the very shallow water (dolphins and finless porpoises are not very sensitive to sounds below 300 Hz, the Airport Authority Hong Kong (AA) stipulated that dedicated terminal vessels not radiate underwater sounds at spectrum levels greater than 110 dB re 1 microPa2/Hz at frequencies above 300 Hz and distances greater than 300 m. The spectrum levels at 300 Hz and higher frequencies of sounds from the tankers arriving, departing, or off-loading at AFRF were less than 110 dB re 1 microPa2/Hz even at distances of 200 m or less. The AA stipulation was met. However, it is presently unknown whether the generally strong noise levels of western Hong Kong inhibit acoustically based feeding and communication, or result in increased stress or permanent shifts in hearing thresholds.

  1. Monitoring programme for the Maasvlakte 2. Part III : The effects of underwater sound

    NARCIS (Netherlands)

    Heinis, F.; De Jong, C.; Ainslie, M.; Borst, W.; Vellinga, T.

    2013-01-01

    The Port of Rotterdam is expanding to meet the growing demand to accommodate large cargo vessels. The construction of Maasvlakte 2 (MV2) started in September 2008. One of the licensing conditions is the monitoring of the underwater sound produced during its construction, with an emphasis on the

  2. Monitoring Programme for the Maasvlakte 2, Part III - The Effects of Underwater Sound

    NARCIS (Netherlands)

    Heinis, F.; Jong, C.A.F. de; Ainslie, M.A.; Borst, W.; Vellinga, T.

    2013-01-01

    The Port of Rotterdam is expanding to meet the growing demand to accommodate large cargo vessels. The construction of Maasvlakte 2 (MV2) started in September 2008. One of the licensing conditions is the monitoring of the underwater sound produced during its construction, with an emphasis on the

  3. Sound Radiation of Cylindrical Shells

    Directory of Open Access Journals (Sweden)

    B Alzahabi

    2016-09-01

    Full Text Available The acoustic signature of submarines is very critical in such high performance structure. Submarines are not only required to sustain very high dynamic loadings at all time, but also being able maneuver and perform their functions under sea without being detected by sonar systems. Submarines rely on low acoustic signature level to remain undetected. Reduction of sound radiation is most efficiently achieved at the design stage. Acoustic signatures may be determined by considering operational scenarios, and modal characteristics. The acoustic signature of submarines is generally of two categories; broadband which has a continuous spectrum; and a tonal noise which has discrete frequencies. The nature of sound radiation of submarine is fiction of its speed. At low speed the acoustic signature is dominated by tonal noise, while at high speed, the acoustic signature is mainly dominated by broadband noise. Submarine hulls are mainly constructed of circular cylindrical shells. Unlike that of simpler structures such as beams and plates, the modal spectrum of cylindrical shell exhibits very unique characteristics. Mode crossing, the uniqueness of modal spectrum, and the redundancy of modal constraints are just to name a few. In cylindrical shells, the lowest natural frequency is not necessarily associated with the lowest wave index. In fact, the natural frequencies do not fall in ascending order of the wave index either. Solution of the vibration problem of cylindrical shells also indicates repeated natural frequencies. These modes are referred to as double peak frequencies. Mode shapes associated with each one of the natural frequencies are usually a combination of Radial (flexural, Longitudinal (axial, and Circumferential (torsional modes. In this paper, the wave equation will be set up in terms of the pressure fluctuations, p(x, t. It will be demonstrated that the noise radiation is a fluctuating pressure wave.

  4. Underwater sound from vessel traffic reduces the effective communication range in Atlantic cod and haddock.

    Science.gov (United States)

    Stanley, Jenni A; Van Parijs, Sofie M; Hatch, Leila T

    2017-11-07

    Stellwagen Bank National Marine Sanctuary is located in Massachusetts Bay off the densely populated northeast coast of the United States; subsequently, the marine inhabitants of the area are exposed to elevated levels of anthropogenic underwater sound, particularly due to commercial shipping. The current study investigated the alteration of estimated effective communication spaces at three spawning locations for populations of the commercially and ecologically important fishes, Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus). Both the ambient sound pressure levels and the estimated effective vocalization radii, estimated through spherical spreading models, fluctuated dramatically during the three-month recording periods. Increases in sound pressure level appeared to be largely driven by large vessel activity, and accordingly exhibited a significant positive correlation with the number of Automatic Identification System tracked vessels at the two of the three sites. The near constant high levels of low frequency sound and consequential reduction in the communication space observed at these recording sites during times of high vocalization activity raises significant concerns that communication between conspecifics may be compromised during critical biological periods. This study takes the first steps in evaluating these animals' communication spaces and alteration of these spaces due to anthropogenic underwater sound.

  5. Experimental findings on the underwater measurements uncertainty of speed of sound and the alignment system

    Science.gov (United States)

    Santos, T. Q.; Alvarenga, A. V.; Oliveira, D. P.; Mayworm, R. C.; Souza, R. M.; Costa-Félix, R. P. B.

    2016-07-01

    Speed of sound is an important quantity to characterize reference materials for ultrasonic applications, for instance. The alignment between the transducer and the test body is an key activity in order to perform reliable and consistent measurement. The aim of this work is to evaluate the influence of the alignment system to the expanded uncertainty of such measurement. A stainless steel cylinder was previously calibrated on an out of water system typically used for calibration of non-destructive blocks. Afterwards, the cylinder was calibrated underwater with two distinct alignment system: fixed and mobile. The values were statistically compared to the out-of-water measurement, considered the golden standard for such application. For both alignment systems, the normalized error was less than 0.8, leading to conclude that the both measurement system (under and out-of-water) do not diverge significantly. The gold standard uncertainty was 2.7 m-s-1, whilst the fixed underwater system resulted in 13 m-s-1, and the mobile alignment system achieved 6.6 m-s-1. After the validation of the underwater system for speed of sound measurement, it will be applied to certify Encapsulated Tissue Mimicking Material as a reference material for biotechnology application.

  6. Oyster larvae settle in response to habitat-associated underwater sounds.

    Science.gov (United States)

    Lillis, Ashlee; Eggleston, David B; Bohnenstiehl, DelWayne R

    2013-01-01

    Following a planktonic dispersal period of days to months, the larvae of benthic marine organisms must locate suitable seafloor habitat in which to settle and metamorphose. For animals that are sessile or sedentary as adults, settlement onto substrates that are adequate for survival and reproduction is particularly critical, yet represents a challenge since patchily distributed settlement sites may be difficult to find along a coast or within an estuary. Recent studies have demonstrated that the underwater soundscape, the distinct sounds that emanate from habitats and contain information about their biological and physical characteristics, may serve as broad-scale environmental cue for marine larvae to find satisfactory settlement sites. Here, we contrast the acoustic characteristics of oyster reef and off-reef soft bottoms, and investigate the effect of habitat-associated estuarine sound on the settlement patterns of an economically and ecologically important reef-building bivalve, the Eastern oyster (Crassostrea virginica). Subtidal oyster reefs in coastal North Carolina, USA show distinct acoustic signatures compared to adjacent off-reef soft bottom habitats, characterized by consistently higher levels of sound in the 1.5-20 kHz range. Manipulative laboratory playback experiments found increased settlement in larval oyster cultures exposed to oyster reef sound compared to unstructured soft bottom sound or no sound treatments. In field experiments, ambient reef sound produced higher levels of oyster settlement in larval cultures than did off-reef sound treatments. The results suggest that oyster larvae have the ability to respond to sounds indicative of optimal settlement sites, and this is the first evidence that habitat-related differences in estuarine sounds influence the settlement of a mollusk. Habitat-specific sound characteristics may represent an important settlement and habitat selection cue for estuarine invertebrates and could play a role in driving

  7. Oyster larvae settle in response to habitat-associated underwater sounds.

    Directory of Open Access Journals (Sweden)

    Ashlee Lillis

    Full Text Available Following a planktonic dispersal period of days to months, the larvae of benthic marine organisms must locate suitable seafloor habitat in which to settle and metamorphose. For animals that are sessile or sedentary as adults, settlement onto substrates that are adequate for survival and reproduction is particularly critical, yet represents a challenge since patchily distributed settlement sites may be difficult to find along a coast or within an estuary. Recent studies have demonstrated that the underwater soundscape, the distinct sounds that emanate from habitats and contain information about their biological and physical characteristics, may serve as broad-scale environmental cue for marine larvae to find satisfactory settlement sites. Here, we contrast the acoustic characteristics of oyster reef and off-reef soft bottoms, and investigate the effect of habitat-associated estuarine sound on the settlement patterns of an economically and ecologically important reef-building bivalve, the Eastern oyster (Crassostrea virginica. Subtidal oyster reefs in coastal North Carolina, USA show distinct acoustic signatures compared to adjacent off-reef soft bottom habitats, characterized by consistently higher levels of sound in the 1.5-20 kHz range. Manipulative laboratory playback experiments found increased settlement in larval oyster cultures exposed to oyster reef sound compared to unstructured soft bottom sound or no sound treatments. In field experiments, ambient reef sound produced higher levels of oyster settlement in larval cultures than did off-reef sound treatments. The results suggest that oyster larvae have the ability to respond to sounds indicative of optimal settlement sites, and this is the first evidence that habitat-related differences in estuarine sounds influence the settlement of a mollusk. Habitat-specific sound characteristics may represent an important settlement and habitat selection cue for estuarine invertebrates and could play a

  8. Repellence Effect of the New Sound for Underwater Speaker of Hydrofoil

    Directory of Open Access Journals (Sweden)

    Tatsunori Nakashima

    2015-06-01

    Full Text Available In order to prevent hydrofoil colliding with cetaceans, the underwater speaker (UWS has been installed to repel cetaceans. Yamada et al. (2012 analyzed and devised the UWS sound as it fits the cetaceans' acoustic properties to prevent the collision furthermore. The new UWS sound was devised and synthesized by Yamada et al. (2015 with expectation of avoiding collision with large cetaceans (Patent applied for, JP2014-171411. In this research project, the new UWS sound was investigated by the playback experiment on humpback whale (Megaptera novaeangliae and by sighting survey in the actual hydrofoil shipping service route. As a result, a physiological and behavioral change of the humpback whale was observed in the playback experiment of the new UWS sound, and the chance of hydrofoil encountering cetaceans of the new UWS sound was smaller than that of the previous UWS sound. Therefore, the improvement of the new UWS sound was confirmed. Lastly, we wish this research project would contribute toward the safer cruise of hydrofoil in the future.

  9. Underwater sound scattering and absorption by a coated infinite plate with attached periodically located inhomogeneities.

    Science.gov (United States)

    Zhang, Yanni; Huang, Hai; Zheng, Jing; Pan, Jie

    2015-11-01

    This paper extends previous work of Zhang and Pan [J. Acoust. Soc. Am. 133(4), 2082-2096 (2013)] on sound scattering and absorption by an underwater coated plate with a single attached distributed-inhomogeneity to that with periodically located distributed-inhomogeneities. A comparison is made among cases of a plate without inhomogeneities, a plate with inhomogeneities, and one with inhomogeneities ignoring the mutual coupling. Results show that coupling of the structural waves scattered by the inhomogeneities plays an important role in modifying the sound absorption and scattering of surface sound pressure, especially at low frequencies and/or the resonance frequencies of the trapped modes of the plate. The sound absorption of the plate is dependent on the distance between the adjacent inhomogeneities, the length of the inhomogeneity, and the angle of the incident sound. On the surface of the inhomogeneities, the scattered/total sound pressure is generally enhanced. On the surface in between the inhomogeneities, the pressure is also enhanced at low frequencies but is nearly unchanged at higher frequencies. Results also show that the coupling-induced variation of scattered/total pressure is significant only at the resonance frequencies of the global modes and trapped modes. The surface normal velocity is presented to explain the coupling-induced variations in the vibration and pressure fields.

  10. Directional sound radiation from substation transformers

    International Nuclear Information System (INIS)

    Maybee, N.

    2009-01-01

    This paper presented the results of a study in which acoustical measurements at two substations were analyzed to investigate the directional behaviour of typical arrays having 2 or 3 transformers. Substation transformers produce a characteristic humming sound that is caused primarily by vibration of the core at twice the frequency of the power supply. The humming noise radiates predominantly from the tank enclosing the core. The main components of the sound are harmonics of 120 Hz. Sound pressure level data were obtained for various directions and distances from the arrays, ranging from 0.5 m to over 100 m. The measured sound pressure levels of the transformer tones displayed substantial positive and negative excursions from the calculated average values for many distances and directions. The results support the concept that the directional effects are associated with constructive and destructive interference of tonal sound waves emanating from different parts of the array. Significant variations in the directional sound pattern can occur in the near field of a single transformer or an array, and the extent of the near field is significantly larger than the scale of the array. Based on typical dimensions for substation sites, the distance to the far field may be much beyond the substation boundary and beyond typical setbacks to the closest dwellings. As such, the directional sound radiation produced by transformer arrays introduces additional uncertainty in the prediction of substation sound levels at dwellings within a few hundred meters of a substation site. 4 refs., 4 figs.

  11. Sound radiation from finite surfaces

    DEFF Research Database (Denmark)

    Brunskog, Jonas

    2013-01-01

    A method to account for the effect of finite size in acoustic power radiation problem of planar surfaces using spatial windowing is developed. Cremer and Heckl presents a very useful formula for the power radiating from a structure using the spatially Fourier transformed velocity, which combined...... with spatially windowing of a plane waves can be used to take into account the finite size. In the present paper, this is developed by means of a radiation impedance for finite surfaces, that is used instead of the radiation impedance for infinite surfaces. In this way, the spatial windowing is included...... in the radiation formula directly, and no pre-windowing is needed. Examples are given for the radiation efficiency, and the results are compared with results found in the literature....

  12. Underwater sound emissions and effects of the pile driving of the OWEZ windfarm facility near Egmond aan Zee (Tconstruct)

    NARCIS (Netherlands)

    Haan, de D.; Burggraaf, D.; Ybema, M.S.; Hille Ris Lambers, R.

    2007-01-01

    The aim of this part of the Monitoring and Evaluation Program NSW (MEP-NSW), i.e. “acoustic measurements”, is to measure and analyze underwater sound emissions from the construction of the OWEZ wind farm and to investigate the effects to marine animals (in particular fish, harbour porpoises and

  13. Semi-active control of piezoelectric coating's underwater sound absorption by combining design of the shunt impedances

    Science.gov (United States)

    Sun, Yang; Li, Zhaohui; Huang, Aigen; Li, Qihu

    2015-10-01

    Piezoelectric shunt damping technology has been applied in the field of underwater sound absorption in recent years. In order to achieve broadband echo reduction, semi-active control of sound absorption of multi-layered piezoelectric coating by shunt damping is significant. In this paper, a practical method is proposed to control the underwater sound absorption coefficients of piezoelectric coating layers by combining design of the shunt impedance that allows certain sound absorption coefficients at setting frequencies. A one-dimensional electro-acoustic model of the piezoelectric coating and the backing is established based on the Mason equivalent circuit theory. First, the shunt impedance of the coating is derived under the constraint of sound absorption coefficient at one frequency. Then, taking the 1-3 piezoelectric composite coating as an example, the sound absorption properties of the coating shunted to the designed shunt impedance are investigated. Next, on the basis of that, an iterative method for two constrained frequencies and an optimizing algorithm for multiple constrained frequencies are provided for combining design of the shunt impedances. At last, an experimental sample with four piezoelectric material layers is manufactured, of which the sound absorption coefficients are measured in an impedance tube. The experimental results show good agreement with the finite element simulation results. It is proved that a serial R-L circuit can control the peak frequency, maximum and bandwidth of the sound absorption coefficient and the combining R-L circuits shunted to multiple layers can control the sound absorption coefficients at multiple frequencies.

  14. Theoretical Modelling of Sound Radiation from Plate

    Science.gov (United States)

    Zaman, I.; Rozlan, S. A. M.; Yusoff, A.; Madlan, M. A.; Chan, S. W.

    2017-01-01

    Recently the development of aerospace, automotive and building industries demands the use of lightweight materials such as thin plates. However, the plates can possibly add to significant vibration and sound radiation, which eventually lead to increased noise in the community. So, in this study, the fundamental concept of sound pressure radiated from a simply-supported thin plate (SSP) was analyzed using the derivation of mathematical equations and numerical simulation of ANSYS®. The solution to mathematical equations of sound radiated from a SSP was visualized using MATLAB®. The responses of sound pressure level were measured at far field as well as near field in the frequency range of 0-200 Hz. Result shows that there are four resonance frequencies; 12 Hz, 60 Hz, 106 Hz and 158 Hz were identified which represented by the total number of the peaks in the frequency response function graph. The outcome also indicates that the mathematical derivation correlated well with the simulation model of ANSYS® in which the error found is less than 10%. It can be concluded that the obtained model is reliable and can be applied for further analysis such as to reduce noise emitted from a vibrating thin plate.

  15. Risk mapping for sensitive species to underwater anthropogenic sound emissions: model development and validation in two Mediterranean areas.

    Science.gov (United States)

    Azzellino, A; Lanfredi, C; D'Amico, A; Pavan, G; Podestà, M; Haun, J

    2011-01-01

    Recent observations of cetacean mass strandings, coincident with anthropogenic sounds emissions, have raised concerns on the potential environmental impact of underwater noise. Cuvier's beaked whale (Ziphius cavirostris) was reported in all the cited stranding events. Within the NATO Marine Mammal Risk Mitigation project (MMRM), multiple interdisciplinary sea trials have been conducted in the Mediterranean Sea with the objective of developing tools and procedures to mitigate the impact of underwater sound emissions. During these cruises, visual observations, passive acoustic detections and environmental data were collected. The aim of this study was to evaluate "a priori" predictions of Cuvier's beaked whale presence in the Alboran Sea, using models developed in the Ligurian Sea that employ bathymetric and chlorophyll features as predictors. The accuracy of these predictions was found adequate and elements are given to account for the uncertainties associated to the use of models developed in areas different from their calibration site. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Seasonal variation of solar radiation and underwater irradiance in the Seto Inland Sea

    OpenAIRE

    Endo, Takuo; Matsuda, Osamu; Imabayashi, Hiromichi

    1983-01-01

    The recent rapid eutrophication of the coastal seas of Japan has had a remarkable effect on the turbidity and transparency of the sea water, hence on the attenuation of underwater irradiance, which in turn influences the phytoplankton communities and primary productivity of the area. The present study deals with the continuous three years observation of the total short-wave radiation, direct short-wave radiation, diffused short-wave radiation and photosynthetically active radiation of tll...

  17. Dolphin Sounds-Inspired Covert Underwater Acoustic Communication and Micro-Modem

    OpenAIRE

    Gang Qiao; Yunjiang Zhao; Songzuo Liu; Muhammad Bilal

    2017-01-01

    A novel portable underwater acoustic modem is proposed in this paper for covert communication between divers or underwater unmanned vehicles (UUVs) and divers at a short distance. For the first time, real dolphin calls are used in the modem to realize biologically inspired Covert Underwater Acoustic Communication (CUAC). A variety of dolphin whistles and clicks stored in an SD card inside the modem helps to realize different biomimetic CUAC algorithms based on the specified covert scenario. I...

  18. The effect of floating deck structures on underwater radiated noise

    NARCIS (Netherlands)

    Bosschaart, C.; Jansen, H.W.; Jong, C.A.F. de; Basten, T.

    2017-01-01

    A concept for underwater machinery noise mitigation of future civil and military ships is the application of a common deck structure, supporting multiple machines, which is installed on resilient mounts on the ship's foundation structure. TNO is addressing the availability and testing of tools to be

  19. A numerical method for the calculation of dynamic response and acoustic radiation from an underwater structure

    Science.gov (United States)

    Zhou, Q.; Joseph, P. F.

    2005-05-01

    An approach combining finite element with boundary element methods is proposed to calculate the elastic vibration and acoustic field radiated from an underwater structure. The FEM software NASTRAN is employed for computation of the structural vibration. An uncoupled boundary element method, based on the potential decomposition technique, is described to determine the acoustic added mass and damping coefficients that result due to fluid loading effects. The acoustic matrices of added mass and damping coefficients are then added to the structural mass and damping matrices, respectively, by the DMAP modules of NASTRAN. Numerical results are shown to be in good agreement with experimental data. The complex eigenvalue analyses of underwater structure are obtained by NASTRAN solution sequence SOL107. Results obtained from this study suggest that the natural frequencies of underwater structures are only weakly dependent on the acoustic frequency if the acoustic wavelength is roughly twice as large as the maximum structural dimension.

  20. Dolphin Sounds-Inspired Covert Underwater Acoustic Communication and Micro-Modem

    Science.gov (United States)

    Qiao, Gang; Liu, Songzuo; Bilal, Muhammad

    2017-01-01

    A novel portable underwater acoustic modem is proposed in this paper for covert communication between divers or underwater unmanned vehicles (UUVs) and divers at a short distance. For the first time, real dolphin calls are used in the modem to realize biologically inspired Covert Underwater Acoustic Communication (CUAC). A variety of dolphin whistles and clicks stored in an SD card inside the modem helps to realize different biomimetic CUAC algorithms based on the specified covert scenario. In this paper, the information is conveyed during the time interval between dolphin clicks. TMS320C6748 and TLV320AIC3106 are the core processors used in our unique modem for fast digital processing and interconnection with other terminals or sensors. Simulation results show that the bit error rate (BER) of the CUAC algorithm is less than 10−5 when the signal to noise ratio is over ‒5 dB. The modem was tested in an underwater pool, and a data rate of 27.1 bits per second at a distance of 10 m was achieved. PMID:29068363

  1. Dolphin Sounds-Inspired Covert Underwater Acoustic Communication and Micro-Modem

    Directory of Open Access Journals (Sweden)

    Gang Qiao

    2017-10-01

    Full Text Available A novel portable underwater acoustic modem is proposed in this paper for covert communication between divers or underwater unmanned vehicles (UUVs and divers at a short distance. For the first time, real dolphin calls are used in the modem to realize biologically inspired Covert Underwater Acoustic Communication (CUAC. A variety of dolphin whistles and clicks stored in an SD card inside the modem helps to realize different biomimetic CUAC algorithms based on the specified covert scenario. In this paper, the information is conveyed during the time interval between dolphin clicks. TMS320C6748 and TLV320AIC3106 are the core processors used in our unique modem for fast digital processing and interconnection with other terminals or sensors. Simulation results show that the bit error rate (BER of the CUAC algorithm is less than 10 − 5 when the signal to noise ratio is over ‒5 dB. The modem was tested in an underwater pool, and a data rate of 27.1 bits per second at a distance of 10 m was achieved.

  2. Dolphin Sounds-Inspired Covert Underwater Acoustic Communication and Micro-Modem.

    Science.gov (United States)

    Qiao, Gang; Zhao, Yunjiang; Liu, Songzuo; Bilal, Muhammad

    2017-10-25

    A novel portable underwater acoustic modem is proposed in this paper for covert communication between divers or underwater unmanned vehicles (UUVs) and divers at a short distance. For the first time, real dolphin calls are used in the modem to realize biologically inspired Covert Underwater Acoustic Communication (CUAC). A variety of dolphin whistles and clicks stored in an SD card inside the modem helps to realize different biomimetic CUAC algorithms based on the specified covert scenario. In this paper, the information is conveyed during the time interval between dolphin clicks. TMS320C6748 and TLV320AIC3106 are the core processors used in our unique modem for fast digital processing and interconnection with other terminals or sensors. Simulation results show that the bit error rate (BER) of the CUAC algorithm is less than 10 - 5 when the signal to noise ratio is over ‒5 dB. The modem was tested in an underwater pool, and a data rate of 27.1 bits per second at a distance of 10 m was achieved.

  3. Characterization of Underwater Sounds Produced by a Backhoe Dredge Excavating Rock and Gravel

    Science.gov (United States)

    2012-12-01

    source levels of the 2,700-m3 hopper dredge The City of Westminster operating on the Hastings Shingle and calculated the broadband source level to 186...Assessment of underwater noise from dredging operations on the Hasting Shingle Bank. Report No. Subacoustech 758R0137. Popper, A. N. 2003. Effects of

  4. Attenuation of low-frequency underwater sound using an array of air-filled balloons and comparison to effective medium theory.

    Science.gov (United States)

    Lee, Kevin M; Wilson, Preston S; Wochner, Mark S

    2017-12-01

    The ultimate goal of this work is to accurately predict the attenuation through a collection of large (on the order of 10-cm-radius) tethered encapsulated bubbles used in underwater noise abatement systems. Measurements of underwater sound attenuation were performed during a set of lake experiments, where a low-frequency compact electromechanical sound source was surrounded by different arrays of encapsulated bubbles with various individual bubbles sizes and void fractions. The measurements were compared with an existing predictive model [Church, J. Acoust. Soc. Am. 97, 1510-1521 (1995)] of the dispersion relation for linear propagation in liquid containing encapsulated bubbles. Although the model was originally intended to describe ultrasound contrast agents, it is evaluated here for large bubbles, and hence low frequencies, as a design tool for future underwater noise abatement systems, and there is good quantitative agreement between the observations and the model.

  5. The baffle influence on sound radiation characteristics of a plate

    Directory of Open Access Journals (Sweden)

    Bao Liu

    2017-01-01

    Full Text Available The acoustic radiation characteristics of the baffle plates and unbaffle plates are calculated and compared by single-layer potential and double-layer potential. Based on the boundary integral equation, the sound pressure integral equation of the baffle and the baffle are deduced respectively. According to the boundary compatibility condition, the sound pressure and the vibration velocity of the plates are obtained. Further, the dynamic equation of the structure is substituted into the vibration equation in the form of the baffle plate and the baffle plate. The sound pressure difference and the displacement of a plate surface are in the form of the vibration mode superposition and the acoustic radiation impedance of the double integral form is obtained, which determines vibration mode coefficient and sound radiation parameters. The effect of the baffle on the acoustic radiation characteristics of the thin plate is analyzed by comparing the acoustic radiation parameters with the simple and simple rectangular plate in water.

  6. The natural horn as an efficient sound radiating system ...

    African Journals Online (AJOL)

    Results obtained showed that the locally made horn are efficient sound radiating systems and are therefore excellent for sound production in local musical renditions. These findings, in addition to the portability and low cost of the horns qualify them to be highly recommended for use in music making and for other purposes ...

  7. On the sound radiation of a rolling tyre

    Science.gov (United States)

    Kropp, Wolfgang; Sabiniarz, Patrick; Brick, Haike; Beckenbauer, Thomas

    2012-04-01

    The sound radiation from rolling tyres is still not very well understood. Although details such as horn effect or directivity during rolling have been investigated, it is not clear which vibrational modes of the tyre structure are responsible for the radiated sound power. In this work an advanced tyre model based on Wave Guide Finite Elements is used in connection with a contact model validated in previous work. With these tools the tyre vibrations during rolling on an ISO surface are simulated. Starting from the calculated contact forces in time the amplitudes of the modes excited during rolling are determined as function of frequency. A boundary element model also validated in previous work is applied to predict the sound pressure level on a reference surface around a tyre placed on rigid ground as function of the modal composition of the tyre vibrations. Taking into account different modes when calculating the vibrational field as input into the boundary element calculations, it is possible to identify individual modes or groups of modes of special relevance for the radiated sound power. The results show that mainly low-order modes with relative low amplitudes but high radiation efficiency in the frequency range around 1 kHz are responsible for the radiated sound power at these frequencies, while those modes which are most strongly excited in that frequency range during rolling are irrelevant for the radiated sound power. This fact is very essential when focusing on the design of quieter tyres.

  8. Sound Radiation of Aerodynamically Excited Flat Plates into Cavities

    Directory of Open Access Journals (Sweden)

    Johannes Osterziel

    2017-10-01

    Full Text Available Flow-induced vibrations and the sound radiation of flexible plate structures of different thickness mounted in a rigid plate are experimentally investigated. Therefore, flow properties and turbulent boundary layer parameters are determined through measurements with a hot-wire anemometer in an aeroacoustic wind tunnel. Furthermore, the excitation of the vibrating plate is examined by laser scanning vibrometry. To describe the sound radiation and the sound transmission of the flexible aluminium plates into cavities, a cuboid-shaped room with adjustable volume and 34 flush-mounted microphones is installed at the non flow-excited side of the aluminium plates. Results showed that the sound field inside the cavity is on the one hand dependent on the flow parameters and the plate thickness and on the other hand on the cavity volume which indirectly influences the level and the distribution of the sound pressure behind the flexible plate through different excited modes.

  9. Suppression of sound radiation to far field of near-field acoustic communication system using evanescent sound field

    OpenAIRE

    Fujii, Ayaka; Wakatsuki, Naoto; Mizutani, Koichi

    2016-01-01

    A method of suppressing sound radiation to the far field of a near-field acoustic communication system using an evanescent sound field is proposed. The amplitude of the evanescent sound field generated from an infinite vibrating plate attenuates exponentially with increasing a distance from the surface of the vibrating plate. However, a discontinuity of the sound field exists at the edge of the finite vibrating plate in practice, which broadens the wavenumber spectrum. A sound wave radiates o...

  10. On the sound radiation from a circular hatchway.

    Science.gov (United States)

    Arenas, Jorge P

    2009-01-01

    Low-frequency sound radiation from vibrating plates is a practical problem often found in engineering applications. In this article, the sound radiation from a circular hatchway is examined using a discrete approach based in the acoustic resistance matrix. Since this matrix can be combined with the volume velocity vector on the discretized vibrating circular surface, the sound radiation efficiency can be estimated through matrix approaches. The limitation of the approach is discussed by using benchmark results presented in previous works. The method produces acceptable results in low frequencies when the response of the plate is dominated by one low structural mode. When the response of more than one mode is significant, the method gives good estimation of the total sound power just for frequencies up to the first resonance. However, the method can be applied to complex and irregular vibrating plane surfaces.

  11. A Direct Radiative Transfer Equation Solver for Path Loss Calculation of Underwater Optical Wireless Channels

    KAUST Repository

    Li, Changping

    2014-11-10

    In this report, we propose a fast numerical solution for the steady state radiative transfer equation in order to calculate the path loss due to light absorption and scattering in various type of underwater channels. In the proposed scheme, we apply a direct non-uniform method to discretize the angular space and an upwind type finite difference method to discretize the spatial space. A Gauss-Seidel iterative method is then applied to solve the fully discretized system of linear equations. The accuracy and efficiency of the proposed scheme is validated by Monte Carlo simulations.

  12. The noisy underwater world : the effect of sound on behaviour of captive zebrafish

    NARCIS (Netherlands)

    Shafiei Sabet, Saeed

    2016-01-01

    Over the past few decades, public attention, activities in the field of conservation and animal welfare by nongovernmental organizations (NGOs), and scientific exploration are raising awareness on the potential effects of sounds on marine mammals and fish species. The aim of this thesis was to

  13. Acoustic inversion with self noise of an autonomous underwater vehicle to measure sound speed in marine sediments

    NARCIS (Netherlands)

    van Leijen, A.V.; Rothkranz, L.J.M.; Groen, F.C.A.

    2009-01-01

    This work reports on an experiment from the Maritime Rapid Environmental Assessment sea trials in 2007, where autonomous underwater vehicles were deployed for environmental assessment. Even though these underwater vehicles are very quiet platforms, this work investigates the potential of vehicle

  14. Observations of shallow water marine ambient sound: the low frequency underwater soundscape of the central Oregon coast.

    Science.gov (United States)

    Haxel, Joseph H; Dziak, Robert P; Matsumoto, Haru

    2013-05-01

    A year-long experiment (March 2010 to April 2011) measuring ambient sound at a shallow water site (50 m) on the central OR coast near the Port of Newport provides important baseline information for comparisons with future measurements associated with resource development along the inner continental shelf of the Pacific Northwest. Ambient levels in frequencies affected by surf-generated noise (f whale vocalizations. Additionally, an increase in spectral levels for frequencies ranging from 35 to 100 Hz is attributed to noise radiated from distant commercial ship commerce. One-second root mean square (rms) sound pressure level (SPLrms) estimates calculated across the 10-840 Hz frequency band for the entire year long deployment show minimum, mean, and maximum values of 84 dB, 101 dB, and 152 dB re 1 μPa.

  15. Analysis of radiation fields in tomography on diffusion gaseous sound

    International Nuclear Information System (INIS)

    Bekman, I.N.

    1999-01-01

    Perspectives of application of equilibrium and stationary variants of diffusion tomography with radioactive gaseous sounds for spatial reconstruction of heterogeneous media in materials technology were considered. The basic attention were allocated to creation of simple algorithms of detection of sound accumulation on the background of monotonically varying concentration field. Algorithms of transformation of two-dimensional radiation field in three-dimensional distribution of radiation sources were suggested. The methods of analytical elongation of concentration field permitting separation of regional anomalies on the background of local ones and vice verse were discussed. It was shown that both equilibrium and stationary variants of diffusion tomography detect the heterogeneity of testing material, provide reduction of spatial distribution of elements of its structure and give an estimation of relative degree of defectiveness

  16. Numerical simulation of aerodynamic sound radiated from a two-dimensional airfoil

    OpenAIRE

    飯田, 明由; 大田黒, 俊夫; 加藤, 千幸; Akiyoshi, Iida; Toshio, Otaguro; Chisachi, Kato; 日立機研; 日立機研; 東大生研; Mechanical Engineering Research Laboratory, Hitachi Ltd.; Mechanical Engineering Research Laboratory, Hitachi Ltd.; University of Tokyo

    2000-01-01

    An aerodynamic sound radiated from a two-dimensional airfoil has been computed with the Lighthill-Curle's theory. The predicted sound pressure level is agreement with the measured one. Distribution of vortex sound sources is also estimated based on the correlation between the unsteady vorticity fluctuations and the aerodynamic sound. The distribution of vortex sound source reveals that separated shear layers generate aerodynamic sound. This result is help to understand noise reduction method....

  17. Frequency-independent radiation modes of interior sound radiation: Experimental study and global active control

    Science.gov (United States)

    Hesse, C.; Papantoni, V.; Algermissen, S.; Monner, H. P.

    2017-08-01

    Active control of structural sound radiation is a promising technique to overcome the poor passive acoustic isolation performance of lightweight structures in the low-frequency region. Active structural acoustic control commonly aims at the suppression of the far-field radiated sound power. This paper is concerned with the active control of sound radiation into acoustic enclosures. Experimental results of a coupled rectangular plate-fluid system under stochastic excitation are presented. The amplitudes of the frequency-independent interior radiation modes are determined in real-time using a set of structural vibration sensors, for the purpose of estimating their contribution to the acoustic potential energy in the enclosure. This approach is validated by acoustic measurements inside the cavity. Utilizing a feedback control approach, a broadband reduction of the global acoustic response inside the enclosure is achieved.

  18. Suppression of sound radiation to far field of near-field acoustic communication system using evanescent sound field

    Science.gov (United States)

    Fujii, Ayaka; Wakatsuki, Naoto; Mizutani, Koichi

    2016-01-01

    A method of suppressing sound radiation to the far field of a near-field acoustic communication system using an evanescent sound field is proposed. The amplitude of the evanescent sound field generated from an infinite vibrating plate attenuates exponentially with increasing a distance from the surface of the vibrating plate. However, a discontinuity of the sound field exists at the edge of the finite vibrating plate in practice, which broadens the wavenumber spectrum. A sound wave radiates over the evanescent sound field because of broadening of the wavenumber spectrum. Therefore, we calculated the optimum distribution of the particle velocity on the vibrating plate to reduce the broadening of the wavenumber spectrum. We focused on a window function that is utilized in the field of signal analysis for reducing the broadening of the frequency spectrum. The optimization calculation is necessary for the design of window function suitable for suppressing sound radiation and securing a spatial area for data communication. In addition, a wide frequency bandwidth is required to increase the data transmission speed. Therefore, we investigated a suitable method for calculating the sound pressure level at the far field to confirm the variation of the distribution of sound pressure level determined on the basis of the window shape and frequency. The distribution of the sound pressure level at a finite distance was in good agreement with that obtained at an infinite far field under the condition generating the evanescent sound field. Consequently, the window function was optimized by the method used to calculate the distribution of the sound pressure level at an infinite far field using the wavenumber spectrum on the vibrating plate. According to the result of comparing the distributions of the sound pressure level in the cases with and without the window function, it was confirmed that the area whose sound pressure level was reduced from the maximum level to -50 dB was

  19. Directivity pattern of the sound radiated from axisymmetric stepped plates.

    Science.gov (United States)

    He, Xiping; Yan, Xiuli; Li, Na

    2016-08-01

    For the purpose of optimal design and efficient utilization of the kind of stepped plate radiator in air, in this contribution, an approach for calculation of the directivity pattern of the sound radiated from a stepped plate in flexural vibration with a free edge is developed based on Kirchhoff-Love hypothesis and Rayleigh integral principle. Experimental tests of directivity pattern for a fabricated flat plate and two fabricated plates with one and two step radiators were carried out. It shows that the configuration of the measured directivity patterns by the proposed analytic approach is similar to those of the calculated approach. Comparison of the agreement between the calculated directivity pattern of a stepped plate and its corresponding theoretical piston show that the former radiator is equivalent to the latter, and the diffraction field generated by the unbaffled upper surface may be small. It also shows that the directivity pattern of a stepped radiator is independent of the metallic material but dependent on the thickness of base plate and resonant frequency. The thicker the thickness of base plate, the more directive the radiation is. The proposed analytic approach in this work may be adopted for any other plates with multi-steps.

  20. Sound quality prediction for engine-radiated noise

    Science.gov (United States)

    Liu, Hai; Zhang, Junhong; Guo, Peng; Bi, Fengrong; Yu, Hanzhengnan; Ni, Guangjian

    2015-05-01

    Diesel engine-radiated noise quality prediction is an important topic because engine noise has a significant impact on the overall vehicle noise. Sound quality prediction is based on subjective and objective evaluation of engine noise. The integrated satisfaction index (ISI) is proposed as a criterion for differentiate noise quality in the subjective evaluation, and five psychoacoustic parameters are selected for characterizing and analyzing the noise quality of the diesel engine objectively. The combination of support vector machines (SVM) and genetic algorithm (GA) is proposed in order to establish a model for predicting the diesel engine-radiated noise quality for all operation conditions. The performance of the GA-SVM model is compared with the BP neural network model, and the results show that the mean relative error of the GA-SVM model is smaller than the BP neural network model. The importance rank of the sound quality metrics to the ISI is indicated by the non-parametric correlation analysis. This study suggests that the GA-SVM model is very useful for accurately predicting the diesel engine-radiated noise quality.

  1. Diel and seasonal patterns of underwater sounds by Weddell seals, leopard seals, and killer whales in the Antarctic: When it's adaptive to be quiet

    Science.gov (United States)

    Mindach, Debrah; Thomas, Jeanette

    2005-09-01

    Automated underwater recordings taken during the austral breeding season of the Weddell seal (Leptonychotes weddellii) in Antarctica also provided data on the vocalizations of predators in the area; leopard seals (Hydrurga leptonyx) and killer whales (Orcinus orca). Weddell seals inhabit fast ice areas to give birth, mate, and molt. Near the end of the breeding season in December the fast ice often breaks out and the two pack ice predators are able to move near the Weddell seal colonies and prey on them, especially pups. Recordings were taken continuously for a 2.5-min period each hour from mid-October 1977 and late-January 1978 at Hutton Cliffs and South Turtle Rock Crack, in McMurdo Sound. The leopard seals increased their trill calls when killer whales came into the area as evidenced by an increase in their frequency-modulated squeak calls. Weddell seals decreased their vocalization rate dramatically (~10 sounds/min) compared to during the peak of the breeding season (~75 sounds/min). Perhaps by being quiet, Weddell seals do not attract predators to their area.

  2. Sound radiation from strip plates with longitudinal stiffeners using waveguide finite and boundary element methods

    International Nuclear Information System (INIS)

    Kim, H.; Ryue, J.

    2014-01-01

    In this study, the vibration characteristics and sound radiation of strip plates with finite width and infinite length are investigated numerically in order to analyze the vibration and sound radiation of structures consisting of many stiffened and double-layered plates. The waveguide finite element approach, which is effective for waveguide structures, is applied as a numerical scheme. The sound power and radiation efficiencies for an unstiffened plate are calculated numerically via coupling boundary elements to the WFEs. Longitudinal stiffeners and additional upper plates are included in the plate model to investigate the effect of stiffeners and an upper plate on sound power and radiation efficiency. In this study, it is found that the stiffeners contribute differently to plate vibration and sound radiation, and that the radiation efficiencies of the stiffened and double plates are larger than those of the unstiffened plate due to the presence of the stiffeners.

  3. Carbon Nanotube Underwater Acoustic Thermophone

    Science.gov (United States)

    2016-09-23

    Attorney Docket No. 300009 1 of 8 A CARBON NANOTUBE UNDERWATER ACOUSTIC THERMOPHONE STATEMENT OF GOVERNMENT INTEREST [0001] The...the Invention [0003] The present invention is an acoustically transparent carbon nanotube thermophone. (2) Description of the Prior Art [0004...amplitude of the resulting sound waves. [0006] Recently, there has been development of underwater acoustic carbon nanotube (CNT) yarn sheets capable

  4. Sound Radiated by a Wave-Like Structure in a Compressible Jet

    Science.gov (United States)

    Golubev, V. V.; Prieto, A. F.; Mankbadi, R. R.; Dahl, M. D.; Hixon, R.

    2003-01-01

    This paper extends the analysis of acoustic radiation from the source model representing spatially-growing instability waves in a round jet at high speeds. Compared to previous work, a modified approach to the sound source modeling is examined that employs a set of solutions to linearized Euler equations. The sound radiation is then calculated using an integral surface method.

  5. Whose Line Sound is it Anyway? Identifying the Vocalizer on Underwater Video by Localizing with a Hydrophone Array

    Directory of Open Access Journals (Sweden)

    Matthias Hoffmann-Kuhnt

    2016-11-01

    Full Text Available A new device that combined high-resolution (1080p wide-angle video and three channels of high-frequency acoustic recordings (at 500 kHz per channel in a portable underwater housing was designed and tested with wild bottlenose and spotted dolphins in the Bahamas. It consisted of three hydrophones, a GoPro camera, a small Fit PC, a set of custom preamplifiers and a high-frequency data acquisition board. Recordings were obtained to identify individual vocalizing animals through time-delay-of-arrival localizing in post-processing. The calculated source positions were then overlaid onto the video – providing the ability to identify the vocalizing animal on the recorded video. The new tool allowed for much clearer analysis of the acoustic behavior of cetaceans than was possible before.

  6. Criteria for Selection of Frequency of Electromagnetic Radiation for Underwater proximity Fuzes

    OpenAIRE

    Sanagapallea Koteswara Rao

    1991-01-01

    Electromagnetic proximity fuzes play important role in underwater weapons. The characteristics of the electromagnetic field, i.e., the wavelength, penetration, propagation constant, velocity, etc in sea water are different from those in air. The conducting properties of the medium are strongly dependent on the frequency of the electromagnetic waves. This paper highlights the basis for selection of frequency of electromagnetic propagation for such applications as proximity fuze for unde...

  7. Aspect-dependent radiated noise analysis of an underway autonomous underwater vehicle.

    Science.gov (United States)

    Gebbie, John; Siderius, Martin; Allen, John S

    2012-11-01

    This paper presents an analysis of the acoustic emissions emitted by an underway REMUS-100 autonomous underwater vehicle (AUV) that were obtained near Honolulu Harbor, HI using a fixed, bottom-mounted horizontal line array (HLA). Spectral analysis, beamforming, and cross-correlation facilitate identification of independent sources of noise originating from the AUV. Fusion of navigational records from the AUV with acoustic data from the HLA allows for an aspect-dependent presentation of calculated source levels of the strongest propulsion tone.

  8. Sound Radiation from an Elastically Restrained Plate Covered by an Acoustic Decoupling Layer

    Directory of Open Access Journals (Sweden)

    Gang Wang

    2015-01-01

    Full Text Available The sound radiation from elastically restrained plates covered by a decoupling layer is studied using the Spectrogeometric Method (SGM, which is a meshless and parametric modeling technique. By adopting the Rayleigh-Ritz procedure and the Rayleigh integral, a vibroacoustic coupling system is established. This model studies the situation when the plate is immersed in heavy fluid, such as water, in which the strong coupling between the structure and sound field should be fully considered. The influence of the boundary conditions on the radiated sound power and sound reduction provided by the decoupling layer based on the locally reacting model is studied. The nonuniform distributed decoupling layer is also studied to analyze the sound reduction effect. The sound intensity on the outer surface of the decoupling layer is investigated and tends to be uniform along the plate scale with increasing thickness of the decoupling layer.

  9. Seabed sediment classification for monitoring underwater nourishments using time series of multi-beam echo-soundings

    Science.gov (United States)

    Gaida, T. C.; Snellen, M.; van Dijk, T. A. G. P.; Simons, D. G.

    2017-12-01

    Coastal erosion induced by natural processes, such as wind, waves, tidal currents, or human interferences endangers human beings, infrastructure, fauna and flora at the oceans and rivers all over the world. In The Netherlands, in particular the North Sea islands are strongly affected by sediment erosion. To protect and stabilize the coastline, beach and shoreface nourishments are frequently performed. Thereby, sediment reservoirs are created that replace the eroded sediments. Increasing the long-term efficiency of coastal protection requires monitoring of the temporal and spatial development of the coastal nourishments. Multi-beam echo-sounders (MBES) allow for detailed and comprehensive investigations of the seabed composition and structure. To investigate the potential of using MBES for monitoring nourishments in a tidal inlet, four MBES surveys per year are carried out at the Dutch Wadden island Ameland. A pre-nourishment MBES survey was performed in April 2017 and the subsequent post-nourishment survey will take place in September 2017. Both surveys are equipped with a Kongsberg EM 2040C dual-head MBES and are supported with extensive grab sampling. In this study the use of MBES backscatter and bathymetry data are considered as an approach for monitoring coastal nourishments. The aim is to develop a monitoring procedure that allows for comparing MBES data taken during different surveys, i.e., with variations in environmental conditions, MBES characteristics and acquisition procedures. Different unsupervised and supervised acoustic seafloor classification techniques are applied to the processed MBES data to classify the seabed sediments. The analysis of the pre-nourishment MBES data indicates that the backscatter and consequently the classification are highly driven by the abundancy of shell fragments. These results will be used as a baseline to investigate the accumulation of the underwater nourishments. Independent grab samples will be used to select the

  10. Wave field synthesis of moving virtual sound sources with complex radiation properties.

    Science.gov (United States)

    Ahrens, Jens; Spors, Sascha

    2011-11-01

    An approach to the synthesis of moving virtual sound sources with complex radiation properties in wave field synthesis is presented. The approach exploits the fact that any stationary sound source of finite spatial extent radiates spherical waves at sufficient distance. The angular dependency of the radiation properties of the source under consideration is reflected by the amplitude and phase distribution on the spherical wave fronts. The sound field emitted by a uniformly moving monopole source is derived and the far-field radiation properties of the complex virtual source under consideration are incorporated in order to derive a closed-form expression for the loudspeaker driving signal. The results are illustrated via numerical simulations of the synthesis of the sound field of a sample moving complex virtual source.

  11. Sound

    CERN Document Server

    Robertson, William C

    2003-01-01

    Muddled about what makes music? Stuck on the study of harmonics? Dumbfounded by how sound gets around? Now you no longer have to struggle to teach concepts you really don t grasp yourself. Sound takes an intentionally light touch to help out all those adults science teachers, parents wanting to help with homework, home-schoolers seeking necessary scientific background to teach middle school physics with confidence. The book introduces sound waves and uses that model to explain sound-related occurrences. Starting with the basics of what causes sound and how it travels, you'll learn how musical instruments work, how sound waves add and subtract, how the human ear works, and even why you can sound like a Munchkin when you inhale helium. Sound is the fourth book in the award-winning Stop Faking It! Series, published by NSTA Press. Like the other popular volumes, it is written by irreverent educator Bill Robertson, who offers this Sound recommendation: One of the coolest activities is whacking a spinning metal rod...

  12. Sensitivity to plant modelling uncertainties in optimal feedback control of sound radiation from a panel

    DEFF Research Database (Denmark)

    Mørkholt, Jakob

    1997-01-01

    Optimal feedback control of broadband sound radiation from a rectangular baffled panel has been investigated through computer simulations. Special emphasis has been put on the sensitivity of the optimal feedback control to uncertainties in the modelling of the system under control.A model...... in terms of a set of radiation filters modelling the radiation dynamics.Linear quadratic feedback control applied to the panel in order to minimise the radiated sound power has then been simulated. The sensitivity of the model based controller to modelling uncertainties when using feedback from actual...

  13. Sound

    CERN Document Server

    2013-01-01

    Sound has the power to soothe, excite, warn, protect, and inform. Indeed, the transmission and reception of audio signals pervade our daily lives. Readers will examine the mechanics and properties of sound and provides an overview of the "interdisciplinary science called acoustics." Also covered are functions and diseases of the human ear.

  14. Active structural acoustic control for reduction of radiated sound from structure

    International Nuclear Information System (INIS)

    Hong, Jin Seok; Oh, Jae Eung

    2001-01-01

    Active control of sound radiation from a vibrating rectangular plate by a steady-state harmonic point force disturbance is experimentally studied. Structural excitation is achieved by two piezoceramic actuators mounted on the panel. Two accelerometers are implemented as error sensors. Estimated radiated sound signals using vibro-acoustic path transfer function are used as error signals. The vibro-acoustic path transfer function represents system between accelerometers and microphones. The approach is based on a multi-channel filtered-x LMS algorithm. The results shows that attenuation of sound levels of 11dB, 10dB is achieved

  15. Active control of radiated sound power from a baffled, rectangular panel

    DEFF Research Database (Denmark)

    Mørkholt, Jakob

    1996-01-01

    with an array of eleven microphones in front of the panel, is very close to minimising the actual radiated sound power. Practical experiments where such an array estimate has been minimised using the filtered X LMS algorithm have shown that substantial reductions of radiated sound power can be obtained over......Active control of radiated sound power from a rectangular baffled panel by minimisation of an accurate power estimate, using piezoceramic actuators, has been investigated. Computer simulations have shown that minimising a power estimate obtained by discretised integration of the far field intensity...... a broad frequency range using few piezoceramic actuators, provided that an accurate estimate of the sound power is available for minimisation....

  16. The influence of the internal sound field of factories on sound radiation from cladding systems

    International Nuclear Information System (INIS)

    Oldham, D.J.; Rowell, M.A.

    1989-01-01

    The transmission loss of factory cladding panels is usually measured in transmission suites where the exciting sound field is classically reverberant. In this situation the transmission characteristics of the panel are determined by forced transmission below the critical frequency and by resonant transmission above the critical frequency. Forced transmission results from the spatial matching of stationary waves of the source room sound field with mode shapes of the test panel. These mode shapes are forced to vibrate at a frequency which is higher than their natural frequency. Above the critical frequency resonant transmission takes place because of a flow of energy between resonant modes in the source room and the panel. Unlike the case of the proportionate room where, within a certain distance from the source, a reverberant field level is established which does not change with increased distance from the source, the noise level in a disproportionate room exhibits a steady decrease with increasing distance from the source. Thus the mechanism of sound transmission of a panel in this situation will not be the same as in the conventional transmission suite and it is possible that transmission loss data obtained by conventional methods is not applicable to the disproportionate factory situation. In this paper the results of a series of scale model experiments are described in which the transmission loss of a panel is measured when subjected to both a classically reverberant sound field and the sound field in a disproportionate room

  17. Sound

    CERN Document Server

    Rivera, Andrea

    2017-01-01

    Sound is all around us. Learn how it is used in art, technology, and engineering. Five easy-to-read chapters explain the science behind sound, as well as its real-world applications. Vibrant, full-color photos, bolded glossary words, and a key stats section let readers zoom in even deeper. Aligned to Common Core Standards and correlated to state standards. Abdo Zoom is a division of ABDO.

  18. Airframe related aeroacoustics of transport aircraft� -research into prediction and reduction of sound radiation-�

    OpenAIRE

    Delfs, Jan Werner

    2013-01-01

    As the sound generation in turbofan engines has decreased the significance of airframe related sound has increased. For example in landing approach the sound associated with the airframe may even dominate the overall sound radiation of an aircraft. The influence of the airframe on aerosound is threefold: i) Airframe components subjected to either their own turbulent boundary layer flow or to installation related turbulent flow act as sources of sound, ii) The aerodynamic influence of the airf...

  19. The effects of viscosity on sound radiation near solid surfaces

    DEFF Research Database (Denmark)

    Morfey, C.L.; Sorokin, Sergey; Gabard, G.

    2012-01-01

    Although the acoustic analogy developed by Lighthill, Curle, and Ffowcs Williams and Hawkings for sound generation by unsteady flow past solid surfaces is formally exact, it has become accepted practice in aeroacoustics to use an approximate version in which viscous quadrupoles are neglected. Here...

  20. Acoustic resonators for the reduction of sound radiation and transmission

    NARCIS (Netherlands)

    Hannink, M.H.C.

    2007-01-01

    Noise is a frequently encountered problem in modern society. One of the environments where the presence of noise causes a deterioration in people’s comfort is in aircraft cabins. For modern aircraft flying at cruise conditions, the main sound source is the turbulent boundary layer around the

  1. Underwater robots

    CERN Document Server

    Antonelli, Gianluca

    2014-01-01

    This book, now at the third edition, addresses the main control aspects in underwater manipulation tasks. The mathematical model with significant impact on the control strategy is discussed. The problem of controlling a 6-degrees-of-freedoms autonomous underwater vehicle is deeply investigated and a survey of fault detection/tolerant strategies for unmanned underwater vehicles is provided. Inverse kinematics, dynamic and interaction control for underwater vehicle-manipulator systems are then discussed. The code used to generate most of the numerical simulations is made available and briefly discussed.       

  2. Assessment on transient sound radiation of a vibrating steel bridge due to traffic loading

    Science.gov (United States)

    Zhang, He; Xie, Xu; Jiang, Jiqing; Yamashita, Mikio

    2015-02-01

    Structure-borne noise induced by vehicle-bridge coupling vibration is harmful to human health and living environment. Investigating the sound pressure level and the radiation mechanism of structure-borne noise is of great significance for the assessment of environmental noise pollution and noise control. In this paper, the transient noise induced by vehicle-bridge coupling vibration is investigated by employing the hybrid finite element method (FEM) and boundary element method (BEM). The effect of local vibration of the bridge deck is taken into account and the sound responses of the structure-borne noise in time domain is obtained. The precision of the proposed method is validated by comparing numerical results to the on-site measurements of a steel girder-plate bridge in service. It implies that the sound pressure level and its distribution in both time and frequency domains may be predicted by the hybrid approach of FEM-BEM with satisfactory accuracy. Numerical results indicate that the vibrating steel bridge radiates high-level noise because of its extreme flexibility and large surface area for sound radiation. The impact effects of the vehicle on the sound pressure when leaving the bridge are observed. The shape of the contour lines in the area around the bridge deck could be explained by the mode shapes of the bridge. The moving speed of the vehicle only affects the sound pressure components with frequencies lower than 10 Hz.

  3. Google™ underwater

    Science.gov (United States)

    Showstack, Randy

    2012-10-01

    The first underwater panoramic images were added to Google Maps™, the company announced on 25 September. This first “underwater Street View collection,” launched in partnership with the Caitlin Seaview Survey, provides people with the opportunity to “become the next virtual Jacques Cousteau.” For more information, see: maps.google.com/ocean.

  4. Active control of sound transmission/radiation from elastic plates by vibration inputs. I - Analysis

    Science.gov (United States)

    Fuller, C. R.

    1990-01-01

    Active control of sound radiation from vibrating plates by oscillating forces applied directly to the structure is analytically studied. The model consists of a plane acoustic wave incident on a clamped elastic circular thin plate. Control is achieved by point forces, and quadratic optimization is used to calculate the optimal control gains necessary to minimize a cost function proportional to the radiated acoustic power (the transmitted field). The results show that global attenuation of broadband radiated sound levels for low to mid-range frequencies can be achieved with one or two control forces, irrespective of whether the system is on or off resonance. The efficiency of the control strategy is demonstrated to be related to the nature of the coupling between the plate modes of response and the radiated field.

  5. BATHYMETRIC SOUNDING by REMOTE SENSING Using ELECTROMAGNETIC RADIATION

    Directory of Open Access Journals (Sweden)

    Frank C Lin

    2016-11-01

    Full Text Available We describe a novel modus operandi to survey the ocean floor. We utilize the eruption of submarine volcanoes as a light source. The electromagnetic radiation emitted by such eruptions illuminate the ocean floor and thus provides information about the barythmetric topology, and a geostationary satellite can monitor this. Since the wavelength of the electromagnetic radiation is many orders of magnitude shorter than that of the acoustic wave, finer details of the bathymetric features can be obtained. We show that a topographical representation of the seabed can be derived from the Signal Diagram by a simple transformation (a mirror reflection. In this case the radiation is emitted by water molecules stimulated by the heat of the volcanic eruption, in contradistinction to the case of tsunami radiation, where the water molecules are stimulated by mutual collisions at high speed. We give two examples: Illapel, Chile and Chichi-shima, Japan. We have also shown that water molecules in the ocean, when stimulated by the heat of submarine volcanic eruption, will emit infrared radiation

  6. Identification of impact force acting on composite laminated plates using the radiated sound measured with microphones

    Science.gov (United States)

    Atobe, Satoshi; Nonami, Shunsuke; Hu, Ning; Fukunaga, Hisao

    2017-09-01

    Foreign object impact events are serious threats to composite laminates because impact damage leads to significant degradation of the mechanical properties of the structure. Identification of the location and force history of the impact that was applied to the structure can provide useful information for assessing the structural integrity. This study proposes a method for identifying impact forces acting on CFRP (carbon fiber reinforced plastic) laminated plates on the basis of the sound radiated from the impacted structure. Identification of the impact location and force history is performed using the sound pressure measured with microphones. To devise a method for identifying the impact location from the difference in the arrival times of the sound wave detected with the microphones, the propagation path of the sound wave from the impacted point to the sensor is examined. For the identification of the force history, an experimentally constructed transfer matrix is employed to relate the force history to the corresponding sound pressure. To verify the validity of the proposed method, impact tests are conducted by using a CFRP cross-ply laminate as the specimen, and an impulse hammer as the impactor. The experimental results confirm the validity of the present method for identifying the impact location from the arrival time of the sound wave detected with the microphones. Moreover, the results of force history identification show the feasibility of identifying the force history accurately from the measured sound pressure using the experimental transfer matrix.

  7. Active control of sound transmission/radiation from elastic plates by vibration inputs. II - Experiments

    Science.gov (United States)

    Metcalf, V. L.; Fuller, C. R.; Silcox, R. J.; Brown, D. E.

    1992-01-01

    Actively controlled harmonic force inputs were applied experimentally to reduce the sound transmitted through an elastic circular plate. The control implementation used a time domain least mean square adaptive algorithm with two error sensors. The control forces were applied directly to the plate by point force vibration inputs, while the error information and performance were measured in the radiated acoustic field by microphones. Test cases were also performed in which the error sensors were accelerometers mounted on the plate. When accelerometers were used as error sensors, the controller performance was degraded; leading to the conclusion that minimizing plate motion does not necessarily lead to an associated decrease in radiated sound levels. In contrast, the results show excellent attenuation of the transmitted sound field when microphone error sensors were used. This result was consistent over a range of frequencies. In addition, the experimental results are compared to previously derived analytical results and the effect of using a point or global minimization scheme is discussed.

  8. Measurement and analysis of radiated sound from a low speed fan with a large tip gap.

    Science.gov (United States)

    Bilka, M J; Anthoine, J; Schram, C

    2014-05-01

    The wake flow field and radiated sound from a low speed axial fan is studied experimentally. The fan geometry uses controlled diffusion blades and is designed with a low aspect ratio (0.9). The fan is installed with a large tip gap, approximately 10% of the blade span. The radiated sound field is analyzed using a known trailing edge noise formulation. First, the model is compared to an experiment of a single airfoil in a wind tunnel to assess the predictive capabilities. Second, measurements of the fan are made at two different blade loading conditions. Hot wire measurements are made in the near wake of the fan to assess the extent of the tip leakage flow for each condition. The radiated sound fields are compared with the trailing edge noise theory. Use is made of the wake measurements as an input to a surface pressure model. When the fan is operated with the optimal blade loading, the influence of the tip leakage flow is found to be of secondary acoustic impact. When the fan is operated at a high loading condition for the blades, a more significant leakage flow develops and is found to be responsible for the dominant radiated sound.

  9. Sound transmission analysis of plate structures using the finite element method and elementary radiator approach with radiator error index

    DEFF Research Database (Denmark)

    Jung, Jaesoon; Kook, Junghwan; Goo, Seongyeol

    2017-01-01

    combines the FEM and Elementary Radiator Approach (ERA) is proposed. The FE-ERA method analyzes the vibrational response of the plate structure excited by incident sound using FEM and then computes the transmitted acoustic pressure from the vibrating plate using ERA. In order to improve the accuracy......In this paper, an accurate and efficient numerical method for sound transmission analysis is presented. As an alternative to conventional numerical methods, such as the Finite Element Method (FEM), Boundary Element Method (BEM) and Statistical Energy Analysis (SEA), the FE-ERA method, which...

  10. Underwater Vehicle

    National Research Council Canada - National Science Library

    Dick, James L

    2007-01-01

    There is thus provided an underwater vehicle having facility for maneuvering alongside a retrieving vehicle, as by manipulation of bow and stern planes, for engaging a hull surface of the retrieving...

  11. Utgrunden off-shore wind farm - Measurements of underwater noise

    International Nuclear Information System (INIS)

    Lindell, Hans

    2003-07-01

    Airicole, GE Wind Energy and SEAS/Energi E2 have initiated this project in order to achieve a better understanding on how offshore based wind farms effect the underwater noise. The main reason is to gain knowledge on how marine wildlife could be effected by this kind of installation. The measurements were performed at Utgrunden wind farm that is situated at the reef Utgrunden on the Swedish southeast coast. The farm consists of seven 1,5 MW turbines. Three hydrophones registered the underwater sound and four accelerometers the tower vibrations. The measurement campaign was conducted during a period from November 2002 to February 2003. The objectives with this project is to answer the following issues and its results are: 1. What is the character of sound from a single power station? - The turbines radiate sound mainly at a few dominating frequencies from 30 Hz up to 800 Hz. At frequencies below 3 Hz no contribution from the turbines can be detected due to the high background level from the waves and the low tower vibration level. 2. What are the sound generating mechanisms in the turbine? - Gearbox mesh frequency vibrations that are transmitted via the tower structure and radiated out to the water mainly generate the sound. Airborne blade sound is effectively dampened in the transition from air to water. 3. How does the sound attenuate with increasing distance at different frequencies? - The average attenuation per doubled distance for frequencies between 31 Hz and 722 Hz is approximately 4 dB in the measured positions. No clear frequency dependence could be found. 4. How does the sound pressure level vary with increasing wind speed? - With increasing wind speed, the sound pressure level increases and the dominating frequencies move upward due to increasing turbine rotational speed. 5. How does sound from different power stations interfere with each other and influence the over all sound image? - No clear tendencies of interference could be observed in this study

  12. Sound Radiation from a Loudspeaker Cabinet using the Boundary Element Method

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren

    Ideally, the walls of a loudspeaker cabinet are rigid. However, in reality, the cabinet is excited by the vibration of the loudspeaker units and by the acoustic pressure inside the cabinet. The radiation of sound caused by such vibration can influence the overall performance of the loudspeaker......, in some cases becoming clearly audible. The aim of this study is to provide a tool that can evaluate the contribution from the cabinet to the overall sound radiated by a loudspeaker. The specific case of a B&O Beolab 9 early prototype has been investigated. An influence by the cabinet of this prototype...... had been reported, based on subjective testing. This study aims to detect the reported problem. The radiation from the cabinet is calculated using the Boundary Element Method. The analysis examines both the frequency domain and the time domain characteristics (in other words, the steady state response...

  13. Radiation of sound in a semi-infinite hard duct inserted axially into a larger infinite lined duct

    Science.gov (United States)

    Tiwana, Mazhar Hussain; Nawaz, Rab; Mann, Amer Bilal

    2017-12-01

    This article examines sound radiation from a hard semi-infinite duct placed symmetrically inside an acoustically lined duct. We introduce a wake on right handed region of the duct configuration to analyze sound radiation process for the trailing edge situation. The integral transforms together with Wiener-Hopf techniques render the solution of underlying problem. However expressions for field intensity involve infinite sums/products that enable solution using truncation approach. The sound radiation analysis is then observed graphically while using different choice of some pertinent parameters. It is worth mentioning that results of leading edge situation can be recovered as a limiting case.

  14. Kinetic theory for radiation interacting with sound waves in ultrarelativistic pair plasmas

    International Nuclear Information System (INIS)

    Marklund, Mattias; Shukla, Padma K.; Stenflo, Lennart

    2006-01-01

    A kinetic theory for radiation interacting with sound waves in an ultrarelativistic electron-positron plasma is developed. It is shown that the effect of a spatial spectral broadening of the electromagnetic pulse is to introduce a reduction of the growth rates for the decay and modulational instabilities. Such spectral broadening could be due to a finite pulse coherence length, or through the use of random phase filters, and would stabilize the propagation of electromagnetic pulses

  15. Forced response sound radiation from acoustically or mechanically excited small plates

    Science.gov (United States)

    Grosveld, Ferdinand W.

    1992-01-01

    Sound radiation from an acoustically excited, clamped aluminum plate is measured and expressed in terms of noise reduction to take into account the incident acoustic excitation field. Its mode shapes and modal frequencies are measured and show good agreement with the predictions from a finite element MSC/NASTRAN model. Noise reduction is measured at 15 points behind the plate and demonstrate good agreement with predictions employing the SYSNOISE numerical analysis system for acoustic-structure interaction.

  16. Separation of radiated sound field components from waves scattered by a source under non-anechoic conditions

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn

    2010-01-01

    A method of estimating the sound field radiated by a source under non-anechoic conditions has been examined. The method uses near field acoustic holography based on a combination of pressure and particle velocity measurements in a plane near the source for separating outgoing and ingoing wave...... components. The outgoing part of the sound field is composed of both radiated and scattered waves. The method compensates for the scattered components of the outgoing field on the basis of the boundary condition of the problem, exploiting the fact that the sound field is reconstructed very close...... to the source. Thus the radiated free-field component is estimated simultaneously with solving the inverse problem of reconstructing the sound field near the source. The method is particularly suited to cases in which the overall contribution of reflected sound in the measurement plane is significant....

  17. Measuring Ultraviolet Radiation Underwater: A Practical Application of the Beer-Lambert-Bouguer Law for High School Physics

    Science.gov (United States)

    Schouten, Peter; Parisi, Alfio; Downs, Nathan

    2009-01-01

    The measurement of solar UV under water is not a simple process. In the underwater environment the difficulty of obtaining useable data is greatly amplified due to the optically complicated and at times unpredictable nature of water itself. The following practical exercise designed for use in the Year 11 and Year 12 Physics classroom aims to…

  18. Propagation of sound

    DEFF Research Database (Denmark)

    Wahlberg, Magnus; Larsen, Ole Næsbye

    2017-01-01

    properties can be modified by sound absorption, refraction, and interference from multi paths caused by reflections.The path from the source to the receiver may be bent due to refraction. Besides geometrical attenuation, the ground effect and turbulence are the most important mechanisms to influence...... communication sounds for airborne acoustics and bottom and surface effects for underwater sounds. Refraction becomes very important close to shadow zones. For echolocation signals, geometric attenuation and sound absorption have the largest effects on the signals....

  19. Sound a very short introduction

    CERN Document Server

    Goldsmith, Mike

    2015-01-01

    Sound is integral to how we experience the world, in the form of noise as well as music. But what is sound? What is the physical basis of pitch and harmony? And how are sound waves exploited in musical instruments? Sound: A Very Short Introduction looks at the science of sound and the behaviour of sound waves with their different frequencies. It also explores sound in different contexts, covering the audible and inaudible, sound underground and underwater, acoustic and electronic sound, and hearing in humans and animals. It concludes with the problem of sound out of place—noise and its reduction.

  20. Underwater laser imaging system (UWLIS)

    Energy Technology Data Exchange (ETDEWEB)

    DeLong, M. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    Practical limitations with underwater imaging systems area reached when the noise in the back scattered radiation generated in the water between the imaging system and the target obscures the spatial contrast and resolution necessary for target discovery and identification. The advent of high power lasers operating in the blue-green portion of the visible spectrum (oceanic transmission window) has led to improved experimental illumination systems for underwater imaging. Range-gated and synchronously scanned devices take advantage of the unique temporal and spatial coherence properties of laser radiation, respectively, to overcome the deleterious effects of common volume back scatter.

  1. Characterization of Sound Radiation by Unresolved Scales of Motion in Computational Aeroacoustics

    Science.gov (United States)

    Rubinstein, Robert; Zhou, Ye

    1999-01-01

    Evaluation of the sound sources in a high Reynolds number turbulent flow requires time-accurate resolution of an extremely large number of scales of motion. Direct numerical simulations will therefore remain infeasible for the forseeable future: although current large eddy simulation methods can resolve the largest scales of motion accurately the, they must leave some scales of motion unresolved. A priori studies show that acoustic power can be underestimated significantly if the contribution of these unresolved scales is simply neglected. In this paper, the problem of evaluating the sound radiation properties of the unresolved, subgrid-scale motions is approached in the spirit of the simplest subgrid stress models: the unresolved velocity field is treated as isotropic turbulence with statistical descriptors, evaluated from the resolved field. The theory of isotropic turbulence is applied to derive formulas for the total power and the power spectral density of the sound radiated by a filtered velocity field. These quantities are compared with the corresponding quantities for the unfiltered field for a range of filter widths and Reynolds numbers.

  2. Underwater Hearing in Turtles.

    Science.gov (United States)

    Willis, Katie L

    2016-01-01

    The hearing of turtles is poorly understood compared with the other reptiles. Although the mechanism of transduction of sound into a neural signal via hair cells has been described in detail, the rest of the auditory system is largely a black box. What is known is that turtles have higher hearing thresholds than other reptiles, with best frequencies around 500 Hz. They also have lower underwater hearing thresholds than those in air, owing to resonance of the middle ear cavity. Further studies demonstrated that all families of turtles and tortoises share a common middle ear cavity morphology, with scaling best suited to underwater hearing. This supports an aquatic origin of the group. Because turtles hear best under water, it is important to examine their vulnerability to anthropogenic noise. However, the lack of basic data makes such experiments difficult because only a few species of turtles have published audiograms. There are also almost no behavioral data available (understandable due to training difficulties). Finally, few studies show what kinds of sounds are behaviorally relevant. One notable paper revealed that the Australian snake-necked turtle (Chelodina oblonga) has a vocal repertoire in air, at the interface, and under water. Findings like these suggest that there is more to the turtle aquatic auditory scene than previously thought.

  3. Sound radiation from an infinite elastic cylinder with dual-wave propagation-intensity distributions

    Science.gov (United States)

    Fuller, C. R.

    1988-01-01

    The radiation of sound from an elastic cylindrical shell filled with fluid and supporting multiwave propagation is studied analytically. Combinations of supersonic and subsonic shell waves are considered. The radiated field is mapped by using acoustic intensity vectors evaluated at various locations. Both time averaged and instantaneous intensity are investigated. The acoustic intensity is seen to vary markedly with axial distance down the cylinder. The effect is shown to be associated with cross terms in the intensity relations, and its magnitude and location to depend upon the relative phase and amplitudes of individual waves. Subsonic shell waves are demonstrated to interact strongly with supersonic shell waves to cause a large modification in the radiated intensity distributions near the shell surface.

  4. 4th Pacific Rim Underwater Acoustics Conference

    CERN Document Server

    Xu, Wen; Cheng, Qianliu; Zhao, Hangfang

    2016-01-01

    These proceedings are a collection of 16 selected scientific papers and reviews by distinguished international experts that were presented at the 4th Pacific Rim Underwater Acoustics Conference (PRUAC), held in Hangzhou, China in October 2013. The topics discussed at the conference include internal wave observation and prediction; environmental uncertainty and coupling to sound propagation; environmental noise and ocean dynamics; dynamic modeling in acoustic fields; acoustic tomography and ocean parameter estimation; time reversal and matched field processing; underwater acoustic localization and communication as well as measurement instrumentations and platforms. These proceedings provide insights into the latest developments in underwater acoustics, promoting the exchange of ideas for the benefit of future research.

  5. Sound field control in a rectangular room at low frequencies to simulate the sound radiated by a virtual source

    DEFF Research Database (Denmark)

    Orozco, Arturo; Uchiyama, Michiaki; Tohyama, Mikio

    1999-01-01

    The sound reproduced in a room by a conventional audio system is modified because of the acoustic response of the room. In this paper a theoreticalstudy based on computer simulations for the synthesis of a desired sound field in a room is presented. The optimal solution in a continuous region...

  6. Sound Radiation from a Supersonic Jet Passing Through a Partially Open Exhaust Duct

    Science.gov (United States)

    Kandula, Max

    2011-01-01

    The radiation of sound from a perfectly expanded Mach 2.5 cold supersonic jet of 25.4 mm exit diameter flowing through a partially open rigid-walled duct with an upstream i-deflector has been studied experimentally. In the experiments, the nozzle is mounted vertically, with the nozzle exit plane at a height of 73 jet diameters above ground level. Relative to the nozzle exit plane (NEP), the location of the duct inlet is varied at 10, 5, and -1 jet diameters. Far-field sound pressure levels were obtained at 54 jet diameters above ground with the aid of acoustic sensors equally spaced around a circular arc of radius equal to 80 jet diameters from the jet axis. Data on the jet acoustic field for the partially open duct were obtained and compared with those with a free jet and with a closed duct. The results suggest that for the partially open duct the overall sound pressure level (OASPL) decreases as the distance between the NEP and the duct inlet plane decreases, while the opposite trend is observed for the closed duct. It is also concluded that the observed peak frequency in the partially open duct increases above the free jet value as the angle from the duct axis is increased, and as the duct inlet plane becomes closer to the NEP.

  7. Reduction of the Radiating Sound of a Submerged Finite Cylindrical Shell Structure by Active Vibration Control

    Directory of Open Access Journals (Sweden)

    Seung-Bok Choi

    2013-02-01

    Full Text Available In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water.

  8. Three-Dimensional Elasticity Solutions for Sound Radiation of Functionally Graded Materials Plates considering State Space Method

    Directory of Open Access Journals (Sweden)

    Tieliang Yang

    2016-01-01

    Full Text Available This paper presents an analytical study for sound radiation of functionally graded materials (FGM plate based on the three-dimensional theory of elasticity. The FGM plate is a mixture of metal and ceramic, and its material properties are assumed to have smooth and continuous variation in the thickness direction according to a power-law distribution in terms of volume fractions of the constituents. Based on the three-dimensional theory of elasticity and state space method, the governing equations with variable coefficients of the FGM plate are derived. The sound radiation of the vibration plate is calculated with Rayleigh integral. Comparisons of the present results with those of solutions in the available literature are made and good agreements are achieved. Finally, some parametric studies are carried out to investigate the sound radiation properties of FGM plates.

  9. Underwater manipulator

    Science.gov (United States)

    Schrum, P.B.; Cohen, G.H.

    1993-04-20

    Self-contained, waterproof, water-submersible, remote-controlled apparatus is described for manipulating a device, such as an ultrasonic transducer for measuring crack propagation on an underwater specimen undergoing shock testing. The subject manipulator includes metal bellows for transmittal of angular motions without the use of rotating shaft seals or O-rings. Inside the manipulator, a first stepper motor controls angular movement. In the preferred embodiment, the bellows permit the first stepper motor to move an ultrasonic transducer [plus minus]45 degrees in a first plane and a second bellows permit a second stepper motor to move the transducer [plus minus]10 degrees in a second plane orthogonal to the first. In addition, an XY motor-driven table provides XY motion.

  10. Underwater manipulator

    International Nuclear Information System (INIS)

    Schrum, P.B.; Cohen, G.H.

    1993-01-01

    Self-contained, waterproof, water-submersible, remote-controlled apparatus is described for manipulating a device, such as an ultrasonic transducer for measuring crack propagation on an underwater specimen undergoing shock testing. The subject manipulator includes metal bellows for transmittal of angular motions without the use of rotating shaft seals or O-rings. Inside the manipulator, a first stepper motor controls angular movement. In the preferred embodiment, the bellows permit the first stepper motor to move an ultrasonic transducer ±45 degrees in a first plane and a second bellows permit a second stepper motor to move the transducer ±10 degrees in a second plane orthogonal to the first. In addition, an XY motor-driven table provides XY motion

  11. A hybrid finite element approach to modeling sound radiation from circular and rectangular ducts.

    Science.gov (United States)

    Duan, Wenbo; Kirby, Ray

    2012-05-01

    A numerical model based on a hybrid finite element method is developed that seeks to join sound pressure fields in interior and exterior regions. The hybrid method is applied to the analysis of sound radiation from open pipes, or ducts, and uses mode matching to couple a finite element discretization of the region surrounding the open end of the duct to wave based modal expansions for adjoining interior and exterior regions. The hybrid method facilitates the analysis of ducts of arbitrary but uniform cross section as well the study of conical flanges and here a modal expansion based on spherical harmonics is applied. Predictions are benchmarked against analytic solutions for the limiting cases of flanged and unflanged circular ducts and excellent agreement between the two methods is observed. Predictions are also presented for flanged and unflanged rectangular ducts, and because the hybrid method retains the sparse banded and symmetric matrices of the traditional finite element method, it is shown that predictions can be obtained within an acceptable time frame even for a three dimensional problem.

  12. Forward projection of transient sound pressure fields radiated by impacted plates using numerical Laplace transform.

    Science.gov (United States)

    Blais, Jean-François; Ross, Annie

    2009-05-01

    Forward propagation of the transient sound pressure radiated by an impacted plate is presented. It is shown that direct and inverse time domain discrete Fourier transforms, involved in Fourier transform based near-field acoustical holography (NAH), lead to aliasing errors in the reconstructed time signals. Adding trailing zeros to the initial time signals is an inefficient way to reduce time aliasing errors. Hence, the numerical Laplace transform is introduced and a Fourier transform based transient NAH (TNAH) approach is formulated. An error measure is introduced to compare both NAH and TNAH with respect to the propagation distance and the location of the observation point in the projection plane. The percentage of error with TNAH is reduced by more than a factor of 10 without adding trailing zeros to the initial signals. Simulation results are validated experimentally using a free Plexiglas plate impacted at its center.

  13. Specialization for underwater hearing by the tympanic middle ear of the turtle, Trachemys scripta elegans

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, J.; Brandt, Christian; Willis, K. L.

    2012-01-01

    Turtles, like other amphibious animals, face a trade-off between terrestrial and aquatic hearing. We used laser vibrometry and auditory brainstem responses to measure their sensitivity to vibration stimuli and to airborne versus underwater sound. Turtles are most sensitive to sound underwater...

  14. Sound radiation and wing mechanics in stridulating field crickets (Orthoptera: Gryllidae).

    Science.gov (United States)

    Montealegre-Z, Fernando; Jonsson, Thorin; Robert, Daniel

    2011-06-15

    Male field crickets emit pure-tone mating calls by rubbing their wings together. Acoustic radiation is produced by rapid oscillations of the wings, as the right wing (RW), bearing a file, is swept across the plectrum borne on the left wing (LW). Earlier work found the natural resonant frequency (f(o)) of individual wings to be different, but there is no consensus on the origin of these differences. Previous studies suggested that the frequency along the song pulse is controlled independently by each wing. It has also been argued that the stridulatory file has a variable f(o) and that the frequency modulation observed in most species is associated with this variability. To test these two hypotheses, a method was developed for the non-contact measurement of wing vibrations during singing in actively stridulating Gryllus bimaculatus. Using focal microinjection of the neuroactivator eserine into the cricket's brain to elicit stridulation and micro-scanning laser Doppler vibrometry, we monitored wing vibration in actively singing insects. The results show significantly lower f(o) in LWs compared with RWs, with the LW f(o) being identical to the sound carrier frequency (N=44). But during stridulation, the two wings resonate at one identical frequency, the song carrier frequency, with the LW dominating in amplitude response. These measurements also demonstrate that the stridulatory file is a constant resonator, as no variation was observed in f(o) along the file during sound radiation. Our findings show that, as they engage in stridulation, cricket wings work as coupled oscillators that together control the mechanical oscillations generating the remarkably pure species-specific song.

  15. The aquatic tympanic ear: convergent adaptations for underwater hearing in three tetrapods

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, Jakob; Wahlberg, Magnus; Larsen, Ole Næsbye

    pressure, low particle motion medium, and the consequence is that an efficient underwater ear is sensitive to sound pressure. It is often stated that underwater hearing can work efficiently without a middle ear apparatus by bone conduction, since sound is transmitted from water to inner ear tissue...... with little loss. However, the sensitivity of such an ear is limited by the very low particle motion in water. We report on underwater hearing in tetrapods ranging from totally aquatic (the clawed frog Xenopus laevis) and mostly aquatic (the red-eared slider Trachemys scripta) to mostly terrestrial (the...... is modified (cartilaginous or partly cartilaginous). In all three species, the lowest threshold to underwater sound is at this peak frequency and is around 80 dB re 1 µPa. The sensitivity to sound pressure is slightly lower in water than in air, making underwater hearing much more efficient in terms of sound...

  16. Prediction of sound transmission through, and radiation from, panels using a wave and finite element method.

    Science.gov (United States)

    Yang, Yi; Mace, Brian R; Kingan, Michael J

    2017-04-01

    This paper describes the extension of a wave and finite element (WFE) method to the prediction of noise transmission through, and radiation from, infinite panels. The WFE method starts with a conventional finite element model of a small segment of the panel. For a given frequency, the mass and stiffness matrices of the segment are used to form the structural dynamic stiffness matrix. The acoustic responses of the fluids surrounding the structure are modelled analytically. The dynamic stiffness matrix of the segment is post-processed using periodic structure theory, and coupled with those of the fluids. The total dynamic stiffness matrix is used to obtain the response of the medium to an incident acoustic pressure. Excitation of the structure by oblique plane waves and a diffuse sound field are considered. The response to structural excitation and the consequent radiation are determined. Since the size of the WFE model is small, computational times are small. Various example applications are presented to illustrate the approach, including a thin isotropic panel, an antisymmetric, cross-ply sandwich panel and a symmetric panel with an orthotropic core.

  17. Study on the general characteristics of the sound radiation of a rectangular plate with different boundary edge conditions

    International Nuclear Information System (INIS)

    Yoo, Ji Woo

    2010-01-01

    Sound radiation is the most important phenomenon when a structure vibrates, which is strongly dependent on boundary conditions and its shape such as aspect ratio. This paper deals with general aspects of sound radiation from this viewpoint. A particular guided and pinned condition being taken into account here, is that the cross-modal terms can average out for all possible point excitation locations. Then, the average radiation efficiency based on the modal radiation efficiency and corresponding radiation power can numerically be obtained. It is shown that the radiation power of the guided plate is governed by the piston mode as well as the critical frequency. Unlike the pinned plate, no clear corner and edge mode regions below the critical frequency may be found for the guided case. Meanwhile, if the plate damping increases the similar tendency that the radiation efficiency increases below the critical frequency is found, as the vibrational level decreases. For the strip with a large aspect ratio, the radiation power is maximised at frequencies where the wavelength is an integer times the short edge length. This can be seen for both the guided and the pinned boundary conditions

  18. Discovery of Sound in the Sea: Resources for Educators, Students, the Public, and Policymakers.

    Science.gov (United States)

    Vigness-Raposa, Kathleen J; Scowcroft, Gail; Miller, James H; Ketten, Darlene R; Popper, Arthur N

    2016-01-01

    There is increasing concern about the effects of underwater sound on marine life. However, the science of sound is challenging. The Discovery of Sound in the Sea (DOSITS) Web site ( http://www.dosits.org ) was designed to provide comprehensive scientific information on underwater sound for the public and educational and media professionals. It covers the physical science of underwater sound and its use by people and marine animals for a range of tasks. Celebrating 10 years of online resources, DOSITS continues to develop new material and improvements, providing the best resource for the most up-to-date information on underwater sound and its potential effects.

  19. Measurement of Underwater Operational Noise Emitted by Wave and Tidal Stream Energy Devices.

    Science.gov (United States)

    Lepper, Paul A; Robinson, Stephen P

    2016-01-01

    The increasing international growth in the development of marine and freshwater wave and tidal energy harvesting systems has been followed by a growing requirement to understand any associated underwater impact. Radiated noise generated during operation is dependent on the device's physical properties, the sound-propagation environment, and the device's operational state. Physical properties may include size, distribution in the water column, and mechanics/hydrodynamics. The sound-propagation environment may be influenced by water depth, bathymetry, sediment type, and water column acoustic properties, and operational state may be influenced by tidal cycle and wave height among others This paper discusses some of the challenges for measurement of noise characteristics from these devices as well as a case study of the measurement of radiated noise from a full-scale wave energy converter.

  20. The effects of ballast on the sound radiation from railway track

    Science.gov (United States)

    Zhang, Xianying; Thompson, David; Jeong, Hongseok; Squicciarini, Giacomo

    2017-07-01

    In a conventional railway track, the rails are laid on sleepers, usually made of concrete, which are supported by a layer of coarse stones known as ballast. This paper focuses on quantifying the influence that the ballast has on the noise produced by the vibration of the track, particularly on the rail and sleeper radiation ratios. A one-fifth scale model of a railway track has been used to conduct acoustic and vibration measurements. This includes reduced-scale ballast that has been produced with stone sizes in the correct proportions. Two different scaling factors (1:√5 and 1:5) have been adopted for the stone sizes in an attempt to reproduce approximately the acoustic properties of full-scale ballast. It is shown that, although a scale factor of 1:√5 gives a better scaling of the acoustic properties, the stones scaled at 1:5 also give acceptable results. The flow resistivity and porosity of this ballast sample have been measured. These have been used in a local reaction model based on the Johnson-Allard formulation to predict the ballast absorption, showing good agreement with measurements of the absorption coefficient. The effects of the presence of the ballast on the noise radiation from a reduced-scale steel rail and concrete sleeper have been investigated experimentally with the ballast located on a rigid foundation. Comparisons are made with the corresponding numerical predictions obtained by using the boundary element method, in which the ballast is represented by a surface impedance. Additionally the finite element method has been used in which the porous medium is considered as an equivalent fluid. From these results it is shown that the extended reaction model gives better agreement with the measurements. Finally, the effects of the ballast vibration on the sleeper radiation have also been investigated for a case of three sleepers embedded in ballast. The ballast vibration is shown to increase the sound radiation by between 1 and 4.5 dB for

  1. Biophysics of underwater hearing in the clawed frog, Xenopus laevis

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, J; Elepfandt, A

    1995-01-01

    Anesthetized clawed frogs (Xenopus laevis) were stimulated with underwater sound and the tympanic disk vibrations were studied using laser vibrometry. The tympanic disk velocities ranged from 0.01 to 0.5 mm/s (at a sound pressure of 2 Pa) in the frequency range of 0.4-4 kHz and were 20-40 dB higher...

  2. Radiative amplification of sound waves in the winds of O and B stars

    Science.gov (United States)

    Macgregor, K. B.; Hartmann, L.; Raymond, J. C.

    1979-01-01

    The velocity perturbation associated with an outwardly propagating sound wave in a radiation-driven stellar wind gives rise to a periodic Doppler shifting of absorption lines formed in the flow. A linearized theory applicable to optically thin waves is used to show that the resulting fluctuation in the absorption-line force can cause the wave amplitude to grow. Detailed calculations of the acceleration due to a large number of lines indicate that significant amplification can occur throughout the high-velocity portion of winds in which the dominant force-producing lines have appreciable optical depths. In the particular case of the wind of Zeta Pup (O4f), it is found that the e-folding distance for wave growth is considerably shorter than the scale lengths over which the physical properties of the flow vary. A qualitative estimate of the rate at which mechanical energy due to nonlinear waves can be dissipated suggests that this mechanism may be important in heating the supersonic portion of winds of early-type stars.

  3. Radiative amplification of sound waves in the winds of O and B stars

    International Nuclear Information System (INIS)

    MacGregor, K.B.; Hartmann, L.; Raymond, J.C.

    1979-01-01

    The velocity perturbation associated with an outwardly propagating sound wave in a radiation-driven stellar wind gives rise to a periodic Doppler shifting of absorption lines formed in the flow. Using a linearized theory applicable to optically thin waves, we show that the resulting fluctuation in the absorption-line force can cause the wave amplitude to grow. Detailed calculations of the acceleration due to a large number of lines indicate that the significant amplification can occur throughout the high-velocity portion of winds in which the dominant force-producing lines have appreciable optical depths. In the particular case of the wind of zeta Pup (O4f), we find that the e-folding distance for wave growth is considerably shorter than the scale lengths over which the physical properties of the flow vary. A qualitative estimate of the rate at which mechanical energy due to nonlinear waves can be dissipated suggests that this mechanism may be important in heating the supersonic portion of winds of early-type stars

  4. Effect of a serrated trailing edge on sound radiation from nearby quadrupoles.

    Science.gov (United States)

    Karimi, Mahmoud; Croaker, Paul; Kinns, Roger; Kessissoglou, Nicole

    2017-05-01

    A periodic boundary element technique is implemented to study the noise reduction capability of a plate with a serrated trailing edge under quadrupole excitation. It is assumed for this purpose that the quadrupole source tensor is independent of the trailing edge configuration and that the effect of the trailing edge shape is to modify sound radiation from prescribed boundary layer sources. The flat plate is modelled as a continuous structure with a finite repetition of small spanwise segments. The matrix equation formulated by the periodic boundary element method for this 3D acoustic scattering problem is represented as a block Toeplitz matrix. The discrete Fourier transform is employed in an iterative algorithm to solve the block Toeplitz system. The noise reduction mechanism for a serrated trailing edge in the near field is investigated by comparing contour plots obtained from each component of the quadrupole for unserrated and serrated trailing edge plate models. The noise reduction due to the serrated trailing edge is also examined as a function of the source location.

  5. The Impact of Offshore Wind Turbines on Underwater Ambient Noise Levels

    OpenAIRE

    Glegg, Stewart

    2015-01-01

    The underwater sound levels generated by offshore wind turbine farms is a concern because of the possible environmental impact on marine mammals. This paper will consider how sound generated by a wind turbine is transmitted into a shallow water channel. It is shown that the underwater sound levels can be calculated for a typical offshore wind turbine by using the theory of Chapman and Ward (1990) combined with aeroacoustic models of trailing edge noise on the wind turbine blades. A procedure ...

  6. Vortex sound radiation in a flow duct with a dipole source and a flexible wall of finite length.

    Science.gov (United States)

    Chiang, Y K; Choy, Y S; Tang, S K

    2017-03-01

    The noise attenuation of fan-ducted noise at low blade-passage frequency remains a challenge. The present study investigates the noise reduction mechanism of a tensioned membrane housing device that directly controls the sound radiation from the doublet which is enclosed in an infinitely long duct with a point vortex. The time dependent sound radiation mechanism and the vibro-acoustics coupling mechanism of the systems are studied by adopting the potential theory and matched asymptotic expansion technique. The silencing performance of such a passive approach depends on the amplitude and phase of the sound field created by the doublet and the acoustic pressure induced by the membrane oscillation in order to achieve sound cancellation. Results show that the response of membrane vibration is strongly associated with the flow field induced by the grazing uniform flow and also the fluid loading generated by the inviscid vortex. The geometrical property of the cavity and the mechanical properties of the flexible membranes play important roles in controlling the performance of the proposed device.

  7. Characterization of ships as sources of underwater noise

    NARCIS (Netherlands)

    Jong, C.A.F. de

    2009-01-01

    There is a growing interest in the possible impact of anthropogenic underwater noise on marine life [1]. One of the concerns is the increasing contribution of shipping noise, with the growing number and size of commercial ships. Traditionally, underwater radiated noise control was only of interest

  8. Sound absorption of tropical woods and their radiation-induced composites

    International Nuclear Information System (INIS)

    Chia, L.H.L.; Teoh, S.H.; Tharmaratnam, K.; Tan, L.C.

    1988-01-01

    This is a preliminary study on the sound absorption properties of two tropical hardwoods, Light Red Meranti and Ramin, and their wood-polymer composites. Sound absorption is measured using a standing wave apparatus. The samples are of one thickness (7 mm) and cut longitudinally. Wood-polymer composites are made by impregnating the samples with methyl methacrylate which is polymerized in situ through γ-irradiation. Both woods and their composites are better sound absorbers at higher sound frequencies. With partial impregnation, the absorption coefficients are improved upon particularly in the region between 1-3 kHz. (author)

  9. About angular dependence of intensity of absent-minded radiation in approach of the strong dissipation of colliding ionic-sound waves

    International Nuclear Information System (INIS)

    Solikhov, D.K.

    2015-01-01

    Present article is devoted to angular dependence of intensity of absent-minded radiation in approach of the strong dissipation of colliding ionic-sound waves. The operation angular dependence of dimensionless of intensity of absent-minded radiation in two-dimensional field of localisation of a wave of a rating in approach of the strong dissipation of passers is ionic-sound waves is viewed. (author)

  10. On the Use of a Direct Radiative Transfer Equation Solver for Path Loss Calculation in Underwater Optical Wireless Channels

    KAUST Repository

    Li, Changping

    2015-07-22

    In this letter, we propose a fast numerical solution for the steady state radiative transfer equation based on the approach in [1] in order to calculate the optical path loss of light propagation suffering from attenuation due to the absorption and scattering in various water types. We apply an optimal non-uniform method to discretize the angular space and an upwind type finite difference method to discretize the spatial space. A Gauss-Seidel iterative method is then applied to solve the fully discretized system of linear equations. Finally, we extend the resulting radiance in 2-dimensional to 3-dimensional by the azimuthal symmetric assumption to compute the received optical power under the given receiver aperture and field of view. The accuracy and efficiency of the proposed scheme are validated by uniform RTE solver and Monte Carlo simulations.

  11. Underwater Geotechnical Foundations

    National Research Council Canada - National Science Library

    Lee, Landris

    2001-01-01

    This report provides an overview and description of the design and construction of underwater geotechnical foundations and offers preliminary guidance based on past and current technology applications...

  12. Underwater cutting techniques developments

    International Nuclear Information System (INIS)

    Bach, F.-W.

    1990-01-01

    The primary circuit structures of different nuclear powerplants are constructed out of stainless steels, ferritic steels, plated ferritic steels and alloys of aluminium. According to the level of the specific radiation of these structures, it is necessary for dismantling to work with remote controlled cutting techniques. The most successful way to protect the working crew against exposure of radiation is to operate underwater in different depths. The following thermal cutting processes are more or less developed to work under water: For ferritic steels only - flame cutting; For ferritic steels, stainless steels, cladded steels and aluminium alloys - oxy-arc-cutting, arc-waterjet-cutting with a consumable electrode, arc-saw-cutting, plasma-arc-cutting and plasma-arc-saw. The flame cutting is a burning process, all the other processes are melt-cutting processes. This paper explains the different techniques, giving a short introduction of the theory, a discussion of the possibilities with the advantages and disadvantages of these processes giving a view into the further research work in this interesting field. (author)

  13. Evaluating underwater noise regulations for piling noise in Belgium and The Netherlands

    OpenAIRE

    Rumes, B.; Erkman, A.; Haelters, J.

    2016-01-01

    There is concern about possible effects on the marine ecosystem of high levels of underwater noise generated during pile driving for the construction of offshore wind farms. As a result, various national governments in Europe have identified limits of underwater sound levels, as such imposing in many cases the use of noise mitigation measures. In this paper we compare the regulations with regard to impulsive underwater noise in the Belgian wind farm zone with those in the Dutch wind energy zo...

  14. Marine Animal Sound Database. Twelve Years of Tracking 52-Hz Whale Calls from a Unique Source in the North Pacific

    National Research Council Canada - National Science Library

    Watkins, William

    2004-01-01

    Long-term monitoring of underwater sounds using U.S. Navy SOSUS and other hydrophone arrays allowed us to follow the seasonal distribution of underwater calls produced by blue, fin and humpback whales across the North Pacific...

  15. Prediction of radiation ratio and sound transmission of complex extruded panel using wavenumber domain Unite element and boundary element methods

    International Nuclear Information System (INIS)

    Kim, H; Ryue, J; Thompson, D J; Müller, A D

    2016-01-01

    Recently, complex shaped aluminium panels have been adopted in many structures to make them lighter and stronger. The vibro-acoustic behaviour of these complex panels has been of interest for many years but conventional finite element and boundary element methods are not efficient to predict their performance at higher frequencies. Where the cross-sectional properties of the panels are constant in one direction, wavenumber domain numerical analysis can be applied and this becomes more suitable for panels with complex cross-sectional geometries. In this paper, a coupled wavenumber domain finite element and boundary element method is applied to predict the sound radiation from and sound transmission through a double-layered aluminium extruded panel, having a typical shape used in railway carriages. The predicted results are compared with measured ones carried out on a finite length panel and good agreement is found. (paper)

  16. Arctic Climate Observations Using Underwater Sound (ACOUS)

    Science.gov (United States)

    1997-09-30

    of the ice cover in the Arctic Ocean. ACOUS will provide data on the large thermohaline change now occurring in the Arctic Ocean, and advance the...at UAF for a simulation period of 47 years. Two general regimes of circulation with a 15-year period were discovered . Anti-cyclonic circulation

  17. Simulations of Cloud-Radiation Interaction Using Large-Scale Forcing Derived from the CINDY/DYNAMO Northern Sounding Array

    Science.gov (United States)

    Wang, Shuguang; Sobel, Adam H.; Fridlind, Ann; Feng, Zhe; Comstock, Jennifer M.; Minnis, Patrick; Nordeen, Michele L.

    2015-01-01

    The recently completed CINDY/DYNAMO field campaign observed two Madden-Julian oscillation (MJO) events in the equatorial Indian Ocean from October to December 2011. Prior work has indicated that the moist static energy anomalies in these events grew and were sustained to a significant extent by radiative feedbacks. We present here a study of radiative fluxes and clouds in a set of cloud-resolving simulations of these MJO events. The simulations are driven by the large-scale forcing data set derived from the DYNAMO northern sounding array observations, and carried out in a doubly periodic domain using the Weather Research and Forecasting (WRF) model. Simulated cloud properties and radiative fluxes are compared to those derived from the S-PolKa radar and satellite observations. To accommodate the uncertainty in simulated cloud microphysics, a number of single-moment (1M) and double-moment (2M) microphysical schemes in the WRF model are tested. The 1M schemes tend to underestimate radiative flux anomalies in the active phases of the MJO events, while the 2M schemes perform better, but can overestimate radiative flux anomalies. All the tested microphysics schemes exhibit biases in the shapes of the histograms of radiative fluxes and radar reflectivity. Histograms of radiative fluxes and brightness temperature indicate that radiative biases are not evenly distributed; the most significant bias occurs in rainy areas with OLR less than 150 W/ cu sq in the 2M schemes. Analysis of simulated radar reflectivities indicates that this radiative flux uncertainty is closely related to the simulated stratiform cloud coverage. Single-moment schemes underestimate stratiform cloudiness by a factor of 2, whereas 2M schemes simulate much more stratiform cloud.

  18. Underwater Scene Composition

    Science.gov (United States)

    Kim, Nanyoung

    2009-01-01

    In this article, the author describes an underwater scene composition for elementary-education majors. This project deals with watercolor with crayon or oil-pastel resist (medium); the beauty of nature represented by fish in the underwater scene (theme); texture and pattern (design elements); drawing simple forms (drawing skill); and composition…

  19. Infrared radiative transfer modelling in a 3D scattering cloudy atmosphere: Application to limb sounding measurements of cirrus

    International Nuclear Information System (INIS)

    Ewen, G.B.L.; Grainger, R.G.; Lambert, A.; Baran, A.J.

    2005-01-01

    The Monte Carlo cloud scattering forward model (McClouds F M) has been developed to simulate limb radiative transfer in the presence of cirrus clouds, for the purposes of simulating cloud contaminated measurements made by an infrared limb sounding instrument, e.g. the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). A reverse method three-dimensional Monte Carlo transfer model is combined with a line-by-line model for radiative transfer through the non-cloudy atmosphere to explicitly account for the effects of multiple scattering by the clouds. The ice cloud microphysics are characterised by a size distribution of randomly oriented ice crystals, with the single scattering properties of the distribution determined by accurate calculations accounting for non-spherical habit. A comparison of McClouds F M simulations and real MIPAS spectra of cirrus shows good agreement. Of particular interest are several noticeable spectral features (i.e. H 2 O absorption lines) in the data that are replicated in the simulations: these can only be explained by upwelling tropospheric radiation scattered into the line-of-sight by the cloud ice particles

  20. Passive aquatic listener (PAL): An adoptive underwater acoustic recording system for the marine environment

    International Nuclear Information System (INIS)

    Anagnostou, Marios N.; Nystuen, Jeffrey A.; Anagnostou, Emmanouil N.; Papadopoulos, Anastasios; Lykousis, Vassilios

    2011-01-01

    The ambient sound field in the ocean is a combination of natural and manmade sounds. Consequently, the interpretation of the ambient sound field can be used to quantify these processes. In the frequency range from 1 to 50 kHz, the general character of ocean ambient sound is a slowly changing background that is closely associated with local wind speed, interspersed with shorter time scale events such as rain storms, ships and animal calls. At lower frequencies the underwater ambient sound budget includes geologically generated sound activities including underwater volcanic eruptions, seismic and seepage faults that generate bubbles, etc. that can also potentially be classified and quantified. Acoustic data are collected on hydrophones. Hydrophones are simple, robust sensors that can be deployed on most ocean instrumentation systems including surface or sub-surface moorings, bottom mounted systems, drifters, ARGO floats or autonomous underwater platforms. A dedicated oceanic underwater recorder called a passive acoustic listener (PAL) has been developed. A principal issue is to accurately distinguish different sound sources so that they can be quantified as part of a sound budget, and then quantified if appropriate. Based on ongoing data collected from the Poseidon II network the retrieval potential of multi-parameters from underwater sound, including meteorological (i.e., precipitation and winds) and in general geophysical, anthropogenetic (i.e., ships, submarines, etc.) and biological (whales, etc.) sources is presented.

  1. A Brief Review of Anthropogenic Sound in the Oceans

    OpenAIRE

    Studds, Gerry E; Wright, Andrew J

    2007-01-01

    Sound in the oceans is generated by a variety of natural sources, such as breaking waves, rain, and marine animals, as well as a variety of human-produced sources, such as ships, sonars and seismic signals. This overview will begin with a quick review of some basic properties of sound waves with particular reference to differences between the behaviours of these waves underwater versus in air. A basic understanding of the physics of underwater sound is critical to understanding how marine ani...

  2. Radiation exposure by monitors and effects of whistling sound on hearing at workplaces in TV and film production sectors

    International Nuclear Information System (INIS)

    Strasser, H.

    1988-01-01

    Information transmission by means of VDUs, spreading at present rapidly in office work and some branches of the industrial production, is not only an auxiliary means but the essential destination and objective of working activities in specific areas of the media sector. By the progression of the video technique a further concentration of VDT work and the increasing gravity of all advantages and disadvantages is to be expected in the film and TV sectors. The real radiation exposure of the technical staff involved in working with and at monitors and potential risks of hearing by whistling sounds sent out by these apparatuses are analysed and evaluated. Experiences in health hazards by radiation from VDUs in office work had to be adapted adequately to the specific working conditions at work places in film and TV productions. (orig./HP) [de

  3. Underwater Coatings for Contamination Control

    International Nuclear Information System (INIS)

    Julia L. Tripp; Kip Archibald; Ann-Marie Phillips; Joseph Campbell

    2004-01-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) is deactivating several fuel storage basins. Airborne contamination is a concern when the sides of the basins are exposed and allowed to dry during water removal. One way of controlling this airborne contamination is to fix the contamination in place while the pool walls are still submerged. There are many underwater coatings available on the market that are used in marine, naval and other applications. A series of tests were run to determine whether the candidate underwater fixatives are easily applied and adhere well to the substrates (pool wall materials) found in INEEL fuel pools. The four pools considered included (1) Test Area North (TAN-607) with epoxy painted concrete walls; (2) Idaho Nuclear Technology and Engineering Center (INTEC) (CPP-603) with bare concrete walls; (3) Materials Test Reactor (MTR) Canal with stainless steel lined concrete walls; and (4) Power Burst Facility (PBF-620) with stainless steel lined concrete walls on the bottom and epoxy painted carbon steel lined walls on the upper portions. Therefore, the four materials chosen for testing included bare concrete, epoxy painted concrete, epoxy painted carbon steel, and stainless steel. The typical water temperature of the pools varies from 55 F to 80 F dependent on the pool and the season. These tests were done at room temperature. The following criteria were used during this evaluation. The underwater coating must: (1) Be easy to apply; (2) Adhere well to the four surfaces of interest; (3) Not change or have a negative impact on water chemistry or clarity; (4) Not be hazardous in final applied form; and (5) Be proven in other underwater applications. In addition, it is desirable for the coating to have a high pigment or high cross-link density to prevent radiation from penetrating. This paper will detail the testing completed and the test results. A proprietary two-part, underwater epoxy owned by S. G. Pinney and Associates

  4. Vibration and Sound-Radiation Analysis for Designing a Low-Noise Gearbox with a Multi-Stage Helical Gear System

    Science.gov (United States)

    Tanaka, Eiichirou; Houjoh, Haruo; Mutoh, Daisuke; Motoshiromizu, Hirofumi; Ohno, Kousaku; Tanaka, Naoyuki

    A method for predicting gear noise from the vibration step to the sound-generation step of a complete gear system, including a gearbox, was developed. This method consists of three separate steps: gear-vibration analysis by an in-house program, gearbox-vibration analysis by an FEA program, and sound-radiation analysis by a commercial software. By using this method, it can obtain the vibration behavior of the gear and gearbox, and the distribution of the sound-pressure around the gearbox and identify the areas from which noise radiates intensely. To validate the method, we measured the displacement of a gear shaft, the acceleration of points on the surface of the gearbox, and the sound-pressure levels around the gearbox. The measured results agreed well with the corresponding calculations. According to the calculated noise, a low-noise gearbox was designed by adding ribs near the antinodes of the gearbox's vibration mode.

  5. Radiated Sound of a High-Speed Water-Jet-Propelled Transportation Vessel.

    Science.gov (United States)

    Rudd, Alexis B; Richlen, Michael F; Stimpert, Alison K; Au, Whitlow W L

    2016-01-01

    The radiated noise from a high-speed water-jet-propelled catamaran was measured for catamaran speeds of 12, 24, and 37 kn. The radiated noise increased with catamaran speed, although the shape of the noise spectrum was similar for all speeds and measuring hydrophone depth. The spectra peaked at ~200 Hz and dropped off continuously at higher frequencies. The radiated noise was 10-20 dB lower than noise from propeller-driven ships at comparable speeds. The combination of low radiated noise and high speed could be a factor in the detection and avoidance of water-jet-propelled ships by baleen whales.

  6. Development of a GPU-based high-performance radiative transfer model for the Infrared Atmospheric Sounding Interferometer (IASI)

    International Nuclear Information System (INIS)

    Huang Bormin; Mielikainen, Jarno; Oh, Hyunjong; Allen Huang, Hung-Lung

    2011-01-01

    Satellite-observed radiance is a nonlinear functional of surface properties and atmospheric temperature and absorbing gas profiles as described by the radiative transfer equation (RTE). In the era of hyperspectral sounders with thousands of high-resolution channels, the computation of the radiative transfer model becomes more time-consuming. The radiative transfer model performance in operational numerical weather prediction systems still limits the number of channels we can use in hyperspectral sounders to only a few hundreds. To take the full advantage of such high-resolution infrared observations, a computationally efficient radiative transfer model is needed to facilitate satellite data assimilation. In recent years the programmable commodity graphics processing unit (GPU) has evolved into a highly parallel, multi-threaded, many-core processor with tremendous computational speed and very high memory bandwidth. The radiative transfer model is very suitable for the GPU implementation to take advantage of the hardware's efficiency and parallelism where radiances of many channels can be calculated in parallel in GPUs. In this paper, we develop a GPU-based high-performance radiative transfer model for the Infrared Atmospheric Sounding Interferometer (IASI) launched in 2006 onboard the first European meteorological polar-orbiting satellites, METOP-A. Each IASI spectrum has 8461 spectral channels. The IASI radiative transfer model consists of three modules. The first module for computing the regression predictors takes less than 0.004% of CPU time, while the second module for transmittance computation and the third module for radiance computation take approximately 92.5% and 7.5%, respectively. Our GPU-based IASI radiative transfer model is developed to run on a low-cost personal supercomputer with four GPUs with total 960 compute cores, delivering near 4 TFlops theoretical peak performance. By massively parallelizing the second and third modules, we reached 364x

  7. Design and Analysis of Underwater Acoustic Networks with Reflected Links

    Science.gov (United States)

    Emokpae, Lloyd

    Underwater acoustic networks (UWANs) have applications in environmental state monitoring, oceanic profile measurements, leak detection in oil fields, distributed surveillance, and navigation. For these applications, sets of nodes are employed to collaboratively monitor an area of interest and track certain events or phenomena. In addition, it is common to find autonomous underwater vehicles (AUVs) acting as mobile sensor nodes that perform search-and-rescue missions, reconnaissance in combat zones, and coastal patrol. These AUVs are to work cooperatively to achieve a desired goal and thus need to be able to, in an ad-hoc manner, establish and sustain communication links in order to ensure some desired level of quality of service. Therefore, each node is required to adapt to environmental changes and be able to overcome broken communication links caused by external noise affecting the communication channel due to node mobility. In addition, since radio waves are quickly absorbed in the water medium, it is common for most underwater applications to rely on acoustic (or sound) rather than radio channels for mid-to-long range communications. However, acoustic channels pose multiple challenging issues, most notably the high transmission delay due to slow signal propagation and the limited channel bandwidth due to high frequency attenuation. Moreover, the inhomogeneous property of the water medium affects the sound speed profile while the signal surface and bottom reflections leads to multipath effects. In this dissertation, we address these networking challenges by developing protocols that take into consideration the underwater physical layer dynamics. We begin by introducing a novel surface-based reflection scheme (SBR), which takes advantage of the multipath effects of the acoustic channel. SBR works by using reflections from the water surface, and bottom, to establish non-line-of-sight (NLOS) communication links. SBR makes it possible to incorporate both line

  8. Underwater Noise Modelling of Wave Energy Devices

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    Future large-scale implementation of wave energy converts (WECs) will introduce an anthropogenic activity in the ocean which may contribute to underwater noise. The Ocean houses several marine species with acoustic sensibility; consequently the potential impact of the underwater noise needs to be addressed. At present, there are no acoustic impact studies based on acquired data. The WEAM project (Wave Energy Acoustic Monitoring) aims at developing an underwater noise monitoring plan for WECs. The development of an acoustic monitoring plan must consider the sound propagation in the ocean, identify noise sources, understand the operational characteristics and select adequate instrumentation. Any monitoring strategy must involve in-situ measurements. However, the vast distances which sound travels within the ocean, can make in-situ measurements covering the entire area of interest, impracticable. This difficulty can be partially overcome through acoustic numerical modelling. This paper presents a synthetic study, on the application of acoustic forward modelling and the evaluation of the impact of noise produced by wave energy devices on marine mammals using criteria based on audiograms of dolphins, or other species. The idea is to illustrate the application of that methodology, and to show to what extent it allows for estimating distances of impacts due to acoustic noise.

  9. Underwater 3D filming

    Directory of Open Access Journals (Sweden)

    Roberto Rinaldi

    2014-12-01

    Full Text Available After an experimental phase of many years, 3D filming is now effective and successful. Improvements are still possible, but the film industry achieved memorable success on 3D movie’s box offices due to the overall quality of its products. Special environments such as space (“Gravity” and the underwater realm look perfect to be reproduced in 3D. “Filming in space” was possible in “Gravity” using special effects and computer graphic. The underwater realm is still difficult to be handled. Underwater filming in 3D was not that easy and effective as filming in 2D, since not long ago. After almost 3 years of research, a French, Austrian and Italian team realized a perfect tool to film underwater, in 3D, without any constrains. This allows filmmakers to bring the audience deep inside an environment where they most probably will never have the chance to be.

  10. Underwater Glider System Study

    OpenAIRE

    Jenkins, Scott A; Humphreys, Douglas E; Sherman, Jeff; Osse, Jim; Jones, Clayton; Leonard, Naomi; Graver, Joshua; Bachmayer, Ralf; Clem, Ted; Carroll, Paul; Davis, Philip; Berry, Jon; Worley, Paul; Wasyl, Joseph

    2003-01-01

    The goals of this study are to determine how to advance from present capabilities of underwater glider (and hybrid motorglider) technology to what could be possible within the next few years; and to identify critical research issues that must be resolved to make such advancements possible. These goals were pursued by merging archival flight data with numerical model results and system spreadsheet analysis to extrapolate from the present state-of-the–art in underwater (UW) gliders to potential...

  11. Offshore dredger sounds: Source levels, sound maps, and risk assessment

    NARCIS (Netherlands)

    Jong, C.A.F. de; Ainslie, M.A.; Heinis, F.; Janmaat, J.

    2016-01-01

    The underwater sound produced during construction of the Port of Rotterdam harbor extension (Maasvlakte 2) was measured, with emphasis on the contribution of the trailing suction hopper dredgers during their various activities: dredging, transport, and discharge of sediment. Measured source levels

  12. Cymbal and BB underwater transducers and arrays

    Energy Technology Data Exchange (ETDEWEB)

    Newnham, R.E.; Zhang, J.; Alkoy, S.; Meyer, R.; Hughes, W.J.; Hladky-Hennion, A.C.; Cochran, J.; Markley, D. [Materials Research Laboratory, Penn State University, University Park, PA 16802 (United States)

    2002-09-01

    The cymbal is a miniaturized class V flextensional transducer that was developed for use as a shallow water sound projector and receiver. Single elements are characterized by high Q, low efficiency, and medium power output capability. Its low cost and thin profile allow the transducer to be assembled into large flexible arrays. Efforts were made to model both single elements and arrays using the ATILA code and the integral equation formulation (EQI).Millimeter size microprobe hydrophones (BBs) have been designed and fabricated from miniature piezoelectric hollow ceramic spheres for underwater applications such as mapping acoustic fields of projectors, and flow noise sensors for complex underwater structures. Green spheres are prepared from soft lead zirconate titanate powders using a coaxial nozzle slurry process. A compact hydrophone with a radially-poled sphere is investigated using inside and outside electrodes. Characterization of these hydrophones is done through measurement of hydrostatic piezoelectric charge coefficients, free field voltage sensitivities and directivity beam patterns. (orig.)

  13. Characterization of ships as sources of underwater noise

    OpenAIRE

    Jong, C.A.F. de

    2009-01-01

    There is a growing interest in the possible impact of anthropogenic underwater noise on marine life [1]. One of the concerns is the increasing contribution of shipping noise, with the growing number and size of commercial ships. Traditionally, underwater radiated noise control was only of interest for naval [2,3] and fishery research vessels [4]. Due to the potential environmental impact, it becomes also relevant for commercial shipping. The challenge is to bring the expertise from the naval ...

  14. Sound Radiation and Vibration of Composite Panels Excited by Turbulent Flow: Analytical Prediction and Analysis

    Directory of Open Access Journals (Sweden)

    Joana Rocha

    2014-01-01

    structures, in parts where aluminum panels were traditionally being used. An original mathematical framework is presented for the prediction of noise and vibration for composite panels. Results show the effect of panel size, thickness of core, and thickness of face layers on the predictions. Smaller composite panels generally produced lower levels of sound and vibration than longer and wider composite panels. Compared with isotropic panels, the composite panels analyzed generated lower noise levels, although it was observed that noise level was amplified at certain frequencies.

  15. Definition and results of test cases for shipping sound maps

    NARCIS (Netherlands)

    Colin,M.E.G.D.; Ainslie, M.A.; Binnerts, B.; Jong, C.A.F. de; Karasalo, I.; Östberg, M.; Sertlek, H.O.; Folegot, T.; Clorennec, D.

    2015-01-01

    The SONIC (Suppression Of underwater Noise Induced by Cavitation) and AQUO (Achieve QUieter Oceans by shipping noise footprint reduction) projects were awarded within the European Seventh Framework Program to develop tools to investigate and mitigate the effects of underwater sound generated by

  16. Sound and sound sources

    DEFF Research Database (Denmark)

    Larsen, Ole Næsbye; Wahlberg, Magnus

    2017-01-01

    There is no difference in principle between the infrasonic and ultrasonic sounds, which are inaudible to humans (or other animals) and the sounds that we can hear. In all cases, sound is a wave of pressure and particle oscillations propagating through an elastic medium, such as air. This chapter...... is about the physical laws that govern how animals produce sound signals and how physical principles determine the signals’ frequency content and sound level, the nature of the sound field (sound pressure versus particle vibrations) as well as directional properties of the emitted signal. Many...... of these properties are dictated by simple physical relationships between the size of the sound emitter and the wavelength of emitted sound. The wavelengths of the signals need to be sufficiently short in relation to the size of the emitter to allow for the efficient production of propagating sound pressure waves...

  17. Remote Underwater Characterization System - Innovative Technology Summary Report

    International Nuclear Information System (INIS)

    Willis, Walter David

    1999-01-01

    Characterization and inspection of water-cooled and moderated nuclear reactors and fuel storage pools requires equipment capable of operating underwater. Similarly, the deactivation and decommissioning of older nuclear facilities often requires the facility owner to accurately characterize underwater structures and equipment which may have been sitting idle for years. The underwater characterization equipment is often required to operate at depths exceeding 20 ft (6.1 m) and in relatively confined or congested spaces. The typical baseline approach has been the use of radiation detectors and underwater cameras mounted on long poles, or stationary cameras with pan and tilt features mounted on the sides of the underwater facility. There is a perceived need for an inexpensive, more mobile method of performing close-up inspection and radiation measurements in confined spaces underwater. The Remote Underwater Characterization System (RUCS) is a small, remotely operated submersible vehicle intended to serve multiple purposes in underwater nuclear operations. It is based on the commercially-available ''Scallop'' vehicle, but has been modified by Department of Energy's Robotics Technology Development Program to add auto-depth control, and vehicle orientation and depth monitoring at the operator control panel. The RUCS is designed to provide visual and gamma radiation characterization, even in confined or limited access areas. It was demonstrated in August 1998 at Idaho National Engineering and environmental Laboratory (INEEL) as part of the INEEL Large Scale Demonstration and Deployment Project. During the demonstration it was compared in a ''head-to-head'' fashion with the baseline characterization technology. This paper summarizes the results of the demonstration and lessons learned; comparing and contrasting both technologies in the areas of cost, visual characterization, radiological characterization, and overall operations

  18. "Boxnep" advanced modular underwater robot

    OpenAIRE

    Buluev, Ilia

    2016-01-01

    The article discusses the relevance of the underwater vehicles' ability to solve a wide range of problems. The idea put in the basis of this research is designing a modular underwater robot. It allows to mount various equipment and test it in underwater environment. The paper deals with the concept of the robot and its characteristics.

  19. Resources for Underwater Robotics Education

    Science.gov (United States)

    Wallace, Michael L.; Freitas, William M.

    2016-01-01

    4-H clubs can build and program underwater robots from raw materials. An annotated resource list for engaging youth in building underwater remotely operated vehicles (ROVs) is provided. This article is a companion piece to the Research in Brief article "Building Teen Futures with Underwater Robotics" in this issue of the "Journal of…

  20. The radiation of sound by the instability waves of a compressible plane turbulent shear layer

    Science.gov (United States)

    Tam, C. K. W.; Morris, P. J.

    1980-01-01

    The problem of acoustic radiation generated by instability waves of a compressible plane turbulent shear layer is solved. The solution provided is valid up to the acoustic far-field region. It represents a significant improvement over the solution obtained by classical hydrodynamic-stability theory which is essentially a local solution with the acoustic radiation suppressed. The basic instability-wave solution which is valid in the shear layer and the near-field region is constructed in terms of an asymptotic expansion using the method of multiple scales. This solution accounts for the effects of the slightly divergent mean flow. It is shown that the multiple-scales asymptotic expansion is not uniformly valid far from the shear layer. Continuation of this solution into the entire upper half-plane is described. The extended solution enables the near- and far-field pressure fluctuations associated with the instability wave to be determined. Numerical results show that the directivity pattern of acoustic radiation into the stationary medium peaks at 20 degrees to the axis of the shear layer in the downstream direction for supersonic flows. This agrees qualitatively with the observed noise-directivity patterns of supersonic jets.

  1. Hybrid Active/Passive Control of Sound Radiation from Panels with Constrained Layer Damping and Model Predictive Feedback Control

    Science.gov (United States)

    Cabell, Randolph H.; Gibbs, Gary P.

    2000-01-01

    There has been considerable interest over the past several years in applying feedback control methods to problems of structural acoustics. One problem of particular interest is the control of sound radiation from aircraft panels excited on one side by a turbulent boundary layer (TBL). TBL excitation appears as many uncorrelated sources acting on the panel, which makes it difficult to find a single reference signal that is coherent with the excitation. Feedback methods have no need for a reference signal, and are thus suited to this problem. Some important considerations for the structural acoustics problem include the fact that the required controller bandwidth can easily extend to several hundred Hertz, so a digital controller would have to operate at a few kilohertz. In addition, aircraft panel structures have a reasonably high modal density over this frequency range. A model based controller must therefore handle the modally dense system, or have some way to reduce the bandwidth of the problem. Further complicating the problem is the fact that the stiffness and dynamic properties of an aircraft panel can vary considerably during flight due to altitude changes resulting in significant resonant frequency shifts. These considerations make the tradeoff between robustness to changes in the system being controlled and controller performance especially important. Recent papers concerning the design and implementation of robust controllers for structural acoustic problems highlight the need to consider both performance and robustness when designing the controller. While robust control methods such as H1 can be used to balance performance and robustness, their implementation is not easy and requires assumptions about the types of uncertainties in the plant being controlled. Achieving a useful controller design may require many tradeoff studies of different types of parametric uncertainties in the system. Another approach to achieving robustness to plant changes is to

  2. Possibility to sound the atmospheric ozone by a radiosonde equipped with two temperature sensors, sensitive and non-sensitive to the long wave radiation

    Science.gov (United States)

    Kitaoka, T.; Sumi, T.

    1994-01-01

    The sensitiveness of white coated thermistor sensors and non-sensitiveness of the gold coated over white thermistor sensors (which have been manufactured by a vacuum evaporation process) to long wave radiation were ascertained by some simple experiments in-room and also by analyses of some results of experimental soundings. From results of analyses on the temperature discrepancies caused by long wave radiation, the possibility to sound the atmospheric ozone partial pressure by a radiosonde equipped with two kinds of sensors, sensitive and non-sensitive to the long wave radiation was suggested, and the test results of the newly developed software for the deduction of ozone partial pressure in upper layers was also shown. However, it was found that the following is the necessary condition to realize the purpose. The sounding should be made by a radiosonde equipped with three sensors, instead of two, one being non-sensitive to the long wave radiation perfectly, and the other two also non-sensitive partially to the downward one, with two different angles of exposure upward. It is essential for the realization of the purpose to get two different values of temperature discrepancies simultaneously observed by the three sensors mentioned above and to avoid the troublesome effects of the upward long wave radiation.

  3. Underwater detection by using ultrasonic sensor

    Science.gov (United States)

    Bakar, S. A. A.; Ong, N. R.; Aziz, M. H. A.; Alcain, J. B.; Haimi, W. M. W. N.; Sauli, Z.

    2017-09-01

    This paper described the low cost implementation of hardware and software in developing the system of ultrasonic which can visualize the feedback of sound in the form of measured distance through mobile phone and monitoring the frequency of detection by using real time graph of Java application. A single waterproof transducer of JSN-SR04T had been used to determine the distance of an object based on operation of the classic pulse echo detection method underwater. In this experiment, the system was tested by placing the housing which consisted of Arduino UNO, Bluetooth module of HC-06, ultrasonic sensor and LEDs at the top of the box and the transducer was immersed in the water. The system which had been tested for detection in vertical form was found to be capable of reporting through the use of colored LEDs as indicator to the relative proximity of object distance underwater form the sensor. As a conclusion, the system can detect the presence of an object underwater within the range of ultrasonic sensor and display the measured distance onto the mobile phone and the real time graph had been successfully generated.

  4. Sound Hole Sound

    OpenAIRE

    Politzer, David

    2015-01-01

    The volume of air that goes in and out of a musical instrument's sound hole is related to the sound hole's contribution to the volume of the sound. Helmholtz's result for the simplest case of steady flow through an elliptical hole is reviewed. Measurements on multiple holes in sound box geometries and scales relevant to real musical instruments demonstrate the importance of a variety of effects. Electric capacitance of single flat plates is a mathematically identical problem, offering an alte...

  5. Effects of UV-B radiation on near-surface zooplankton of puget sound.

    Science.gov (United States)

    Damkaer, David M; Dey, Douglas B; Heron, Gayle A; Prentice, Earl F

    1980-01-01

    An increase in incident solar ultraviolet irradiation, resulting from possible deterioration of the stratospheric ozone layer, would have important biological effects. Though the oceans are relatively opaque to UV radiation, compared to visible light, increases in incident UV may affect organisms living within the first few meters of the sea surface.Shrimp larvae, crab larvae, and euphausids were exposed to various low levels of simulated solar UV radiation (UV-B, 290-315 nm) under laboratory conditions. Comparisons between solar and artificial spectra were based on spectroradiometric measurements converted to erythemally effective irradiance. These zooplankton tolerated UV-B irradiance levels up to threshold levels with no significant reduction in survival or developmental rates compared to control organisms. Beyond the threshold levels, activity, development, and survival rapidly declined. The apparent UV thresholds are near present incident UV levels.Observed survival threshold levels for each experimental group were superimposed on seasonal solar incident UV levels at the experimental site. These threshold levels appeared to be exceeded by median ambient UV levels late in the season of surface occurrence of each species. UV increases resulting from ozone depletion may significantly shorten this season. Although the apparent impact would be lessened by the decrease in UV with depth, irreversible detrimental effects would probably occur before reported survival thresholds were exceeded.

  6. Sound radiation contrast in MR phase images. Method for the representation of elasticity, sound damping, and sound impedance changes; Schallstrahlungskontrast in MR-Phasenbildern. Methode zur Darstellung von Elastizitaets-, Schalldaempfungs- und Schallimpedanzaenderungen

    Energy Technology Data Exchange (ETDEWEB)

    Radicke, Marcus

    2009-12-18

    The method presented in this thesis combines ultrasound techniques with the magnetic-resonance tomography (MRT). An ultrasonic wave generates in absorbing media a static force in sound-propagation direction. The force leads at sound intensities of some W/cm{sup 2} and a sound frequency in the lower MHz range to a tissue shift in the micrometer range. This tissue shift depends on the sound power, the sound frequency, the sound absorption, and the elastic properties of the tissue. A MRT sequence of the Siemens Healthcare AG was modified so that it measures (indirectly) the tissue shift, codes as grey values, and presents as 2D picture. By means of the grey values the sound-beam slope in the tissue can be visualized, and so additionally sound obstacles (changes of the sound impedance) can be detected. By the MRT images token up spatial changes of the tissue parameters sound absorption and elasticity can be detected. In this thesis measurements are presented, which show the feasibility and future chances of this method especially for the mammary-cancer diagnostics. [German] Die in dieser Arbeit praesentierte Methode kombiniert Ultraschalltechniken mit der Magnetresonanztomographie (MRT). Eine Ultraschallwelle ruft in absorbierenden Medien eine statische Kraft in Schallausbreitungsrichtung hervor. Die Kraft fuehrt bei Schallintensitaeten von einigen W/cm{sup 2} und einer Schallfrequenz im niederen MHz-Bereich zu einer Gewebeverschiebung im Mikrometerbereich. Diese Gewebeverschiebung haengt ab von der Schallleistung, der Schallfrequenz, der Schallabsorption und den elastischen Eigenschaften des Gewebes. Es wurde eine MRT-Sequenz der Siemens Healthcare AG modifiziert, so dass sie (indirekt) die Gewebeverschiebung misst, als Grauwerte kodiert und als 2D-Bild darstellt. Anhand der Grauwerte kann der Schallstrahlverlauf in dem Gewebe visualisiert werden, und so koennen zusaetzlich Schallhindernisse (Aenderungen der Schallkennimpedanz) aufgespuert werden. Mit den

  7. Channel analysis for single photon underwater free space quantum key distribution.

    Science.gov (United States)

    Shi, Peng; Zhao, Shi-Cheng; Gu, Yong-Jian; Li, Wen-Dong

    2015-03-01

    We investigate the optical absorption and scattering properties of underwater media pertinent to our underwater free space quantum key distribution (QKD) channel model. With the vector radiative transfer theory and Monte Carlo method, we obtain the attenuation of photons, the fidelity of the scattered photons, the quantum bit error rate, and the sifted key generation rate of underwater quantum communication. It can be observed from our simulations that the most secure single photon underwater free space QKD is feasible in the clearest ocean water.

  8. Underwater Wireless Acousto-Optic Waveguide (UWAOW)

    Science.gov (United States)

    Giuliano, Giovanni; Kent, Lionel W. J.; Laycock, Leslie C.

    2017-10-01

    The present study originated in the lack of research into achieving underwater total internal reflection (TIR) via the acousto-optic effect. The uniqueness of this technique exists in the fact that it is based on a high sound pressure level which induces a localised change in refractive index of seawater sufficient to achieve total internal reflection within the communication channel. Different transducer systems for generating the pressure wave have been investigated and take the form of a wave which may be either a standing wave, or a novel beamforming technique. The former is based on an array of transducers and with an acoustic mirror at the receiver in order to establish the standing wave. The alternative approach relies on the high intrinsic directionality of a novel beamformer where an annular transducer array is examined as an acoustic source. In this paper, the main characteristics of the acoustic optic waveguide will be presented. This will include both sound and light propagation in the ocean, TIR, novel beam propagation, the refractive index of water as a function of the externally applied acoustic pressure, and the acoustic technology. The modelled results, the limitations imposed by the challenging medium, and the system requirements required to obtain an Underwater Wireless Acousto-Optic Waveguide (UWAOW) will be also addressed.

  9. Underwater laser beam welding of Alloy 690

    International Nuclear Information System (INIS)

    Hino, Takehisa; Tamura, Masataka; Kono, Wataru; Kawano, Shohei; Yoda, Masaki

    2009-01-01

    Stress Corrosion Clacking (SCC) has been reported at Alloy 600 welds between nozzles and safe-end in Pressurized Water Reactor (PWR) plant. Alloy 690, which has higher chromium content than Alloy 600, has been applied for cladding on Alloy 600 welds for repairing damaged SCC area. Toshiba has developed Underwater Laser Beam Welding technique. This method can be conducted without draining, so that the repairing period and the radiation exposure during the repair can be dramatically decreased. In some old PWRs, high-sulfur stainless steel is used as the materials for this section. It has a high susceptibility of weld cracks. Therefore, the optimum welding condition of Alloy 690 on the high-sulfur stainless steel was investigated with our Underwater Laser Beam Welding unit. Good cladding layer, without any crack, porosity or lack of fusion, could be obtained. (author)

  10. Improvements in or relating to the inspection of underwater structures

    International Nuclear Information System (INIS)

    Caldecourt, L.R.; Evans, G.V.; Parsons, T.V.

    1980-01-01

    A radiation detector is described, for use in the inspection of underwater structures, which is capable of withstanding high pressures and arduous marine conditions. The ingress of water into the body of the radiation detector tube is prevented by the use of a resilient waterproof compound. Marine structures incorporating such radiation detectors are described, whereby the presence or density of flowing cement grout in the legs of an offshore platform may be determined. (U.K.)

  11. Efficient approximation of the Struve functions Hn occurring in the calculation of sound radiation quantities.

    Science.gov (United States)

    Aarts, Ronald M; Janssen, Augustus J E M

    2016-12-01

    The Struve functions H n (z), n=0, 1, ...  are approximated in a simple, accurate form that is valid for all z≥0. The authors previously treated the case n = 1 that arises in impedance calculations for the rigid-piston circular radiator mounted in an infinite planar baffle [Aarts and Janssen, J. Acoust. Soc. Am. 113, 2635-2637 (2003)]. The more general Struve functions occur when other acoustical quantities and/or non-rigid pistons are considered. The key step in the paper just cited is to express H 1 (z) as (2/π)-J 0 (z)+(2/π) I(z), where J 0 is the Bessel function of order zero and the first kind and I(z) is the Fourier cosine transform of [(1-t)/(1+t)] 1/2 , 0≤t≤1. The square-root function is optimally approximated by a linear function ĉt+d̂, 0≤t≤1, and the resulting approximated Fourier integral is readily computed explicitly in terms of sin z/z and (1-cos z)/z 2 . The same approach has been used by Maurel, Pagneux, Barra, and Lund [Phys. Rev. B 75, 224112 (2007)] to approximate H 0 (z) for all z≥0. In the present paper, the square-root function is optimally approximated by a piecewise linear function consisting of two linear functions supported by [0,t̂ 0 ] and [t̂ 0 ,1] with t̂ 0 the optimal take-over point. It is shown that the optimal two-piece linear function is actually continuous at the take-over point, causing a reduction of the additional complexity in the resulting approximations of H 0 and H 1 . Furthermore, this allows analytic computation of the optimal two-piece linear function. By using the two-piece instead of the one-piece linear approximation, the root mean square approximation error is reduced by roughly a factor of 3 while the maximum approximation error is reduced by a factor of 4.5 for H 0 and of 2.6 for H 1 . Recursion relations satisfied by Struve functions, initialized with the approximations of H 0 and H 1 , yield approximations for higher order Struve functions.

  12. Underwater laser detection system

    Science.gov (United States)

    Gomaa, Walid; El-Sherif, Ashraf F.; El-Sharkawy, Yasser H.

    2015-02-01

    The conventional method used to detect an underwater target is by sending and receiving some form of acoustic energy. But the acoustic systems have limitations in the range resolution and accuracy; while, the potential benefits of a laserbased underwater target detection include high directionality, high response, and high range accuracy. Lasers operating in the blue-green region of the light spectrum(420 : 570nm)have a several applications in the area of detection and ranging of submersible targets due to minimum attenuation through water ( less than 0.1 m-1) and maximum laser reflection from estimated target (like mines or submarines) to provide a long range of detection. In this paper laser attenuation in water was measured experimentally by new simple method by using high resolution spectrometer. The laser echoes from different targets (metal, plastic, wood, and rubber) were detected using high resolution CCD camera; the position of detection camera was optimized to provide a high reflection laser from target and low backscattering noise from the water medium, digital image processing techniques were applied to detect and discriminate the echoes from the metal target and subtract the echoes from other objects. Extraction the image of target from the scattering noise is done by background subtraction and edge detection techniques. As a conclusion, we present a high response laser imaging system to detect and discriminate small size, like-mine underwater targets.

  13. Underwater Gliders: A Review

    Directory of Open Access Journals (Sweden)

    Javaid Muhammad Yasar

    2014-07-01

    Full Text Available Underwater gliders are a type of underwater vehicle that transverse the oceans by shifting its buoyancy, during which its wings develop a component of the downward motion in the horizontal plane, thus producing a forward force. They are primarily used in oceanography sensing and data collection and play an important role in ocean research and development. Although there have been considerable developments in these gliders since the development of the first glider concept in 1989, to date, no review of these gliders have been done. This paper reviews existing underwater gliders, with emphasis on their respective working principles, range and payload capacity. All information on gliders available in the public domain or published in literature from the year 2000-2013 was reviewed. The majority of these gliders have an operational depth of 1000 m and a payload of less than 25 kg. The exception is a blend-body shape glider, which has a payload of approximately 800 kg and an operational depth around about 300 m. However, the commercialization of these gliders has been limited with only three know examples that have been successfully commercialized.

  14. In-air and underwater hearing of the cormorant

    DEFF Research Database (Denmark)

    Larsen, Ole Næsbye; Wahlberg, Magnus; Christensen-Dalsgaard, Jakob

    Numerous studies have mapped the hearing abilities of birds in air but currently there is little or no data on how diving birds hear or react to sound under water. Therefore, it is unknown whether the ears and auditory system of diving birds are adapted to underwater hearing. In the present study...... 10 cm under water in a large water filled-tank while being artificially ventilated. ABR-responses to calibrated tone bursts produced by a woofer and an underwater speaker, respectively, were measured at different intensities and frequencies to obtain hearing threshold values in air and under water......Hz) under water. Generally, the cormorant ear was not very sensitive to sound, neither in air nor under water. The hearing abilities in water, however, were better than what would have been expected for a purely in-air adapted ear. (Supported by the Carlsberg Foundation 2009_01_0292 and the Danish Council...

  15. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1, S/N 108 2

    Science.gov (United States)

    Valdez, A.

    2000-01-01

    This is the Engineering Test Report, Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1 SIN 108, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

  16. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1, S/N 109

    Science.gov (United States)

    Valdez, A.

    2000-01-01

    This is the Engineering Test Report, Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1, S/N 109, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

  17. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A2, S/N 108, 08

    Science.gov (United States)

    Valdez, A.

    2000-01-01

    This is the Engineering Test Report, Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A2, S/N 108, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

  18. Feed-forward adaptive system for vibration and sound radiation reduction phase I: architecture, definition, and specifications

    Science.gov (United States)

    Concilio, Antonio; De Vivo, Luciano; Quaranta, V.

    1998-06-01

    Noise emission suppression problem is more and more absorbing mechanical designers' efforts, in the recent times. It is not only a matter of comfort, but also of people exposure noise limits. A significant step has been moved in Europe with the issue of the EU Green Paper: Future Noise Policy. Impact on external and internal environment is requested to be considered in industrial and civil design. Low frequency disturbances are hard to be treated by classical passive methods. Active noise control presents great potentialities. In the last years, significant improvements have been attained in the field of interior acoustics, with particular reference to aircraft. Microphones and loudspeakers - based active systems have been put on the market, while interesting alternatives have been proved to be effective, implementing Smart Materials and Structures related concepts. The authors of this paper and of its continuation have been working for a long time inside the themes related to the noise control in aircraft cabins. Thin-walled beams have a certain importance; they are representative of fuselage range. This document deals with the design and the specifications definition, concerning a system addressed to the minimization of the vibration level of, or the sound power level radiated by , a general structure; in the specific case, a thin-walled beam was selected as test article, fully representative of general complex elements. The structure is identified and characterized through its experimental response. The set-up for the active control measurements is then described in detail; the acquired transfer functions have been elaborated to predict the performance of the real active control system.

  19. Seismic and Biological Sources of Ambient Ocean Sound

    Science.gov (United States)

    Freeman, Simon Eric

    Sound is the most efficient radiation in the ocean. Sounds of seismic and biological origin contain information regarding the underlying processes that created them. A single hydrophone records summary time-frequency information from the volume within acoustic range. Beamforming using a hydrophone array additionally produces azimuthal estimates of sound sources. A two-dimensional array and acoustic focusing produce an unambiguous two-dimensional `image' of sources. This dissertation describes the application of these techniques in three cases. The first utilizes hydrophone arrays to investigate T-phases (water-borne seismic waves) in the Philippine Sea. Ninety T-phases were recorded over a 12-day period, implying a greater number of seismic events occur than are detected by terrestrial seismic monitoring in the region. Observation of an azimuthally migrating T-phase suggests that reverberation of such sounds from bathymetric features can occur over megameter scales. In the second case, single hydrophone recordings from coral reefs in the Line Islands archipelago reveal that local ambient reef sound is spectrally similar to sounds produced by small, hard-shelled benthic invertebrates in captivity. Time-lapse photography of the reef reveals an increase in benthic invertebrate activity at sundown, consistent with an increase in sound level. The dominant acoustic phenomenon on these reefs may thus originate from the interaction between a large number of small invertebrates and the substrate. Such sounds could be used to take census of hard-shelled benthic invertebrates that are otherwise extremely difficult to survey. A two-dimensional `map' of sound production over a coral reef in the Hawaiian Islands was obtained using two-dimensional hydrophone array in the third case. Heterogeneously distributed bio-acoustic sources were generally co-located with rocky reef areas. Acoustically dominant snapping shrimp were largely restricted to one location within the area surveyed

  20. Underwater gas tornado

    Science.gov (United States)

    Byalko, Alexey V.

    2013-07-01

    We present the first experimental observation of a new hydrodynamic phenomenon, the underwater tornado. Simple measurements show that the tornado forms a vortex of the Rankine type, i.e. the rising gas rotates as a solid body and the liquid rotates with a velocity decreasing hyperbolically with the radius. We obtain the dependence of the tornado radius a on the gas stream value j theoretically: a ∼ j2/5. Processing of a set of experiments yielded the value 0.36 for the exponent in this expression. We also report the initial stages of the theoretical study of this phenomenon.

  1. Underwater Optical Wireless Channel Modeling Using Monte-Carlo Method

    Science.gov (United States)

    Saini, P. Sri; Prince, Shanthi

    2011-10-01

    At present, there is a lot of interest in the functioning of the marine environment. Unmanned or Autonomous Underwater Vehicles (UUVs or AUVs) are used in the exploration of the underwater resources, pollution monitoring, disaster prevention etc. Underwater, where radio waves do not propagate, acoustic communication is being used. But, underwater communication is moving towards Optical Communication which has higher bandwidth when compared to Acoustic Communication but has shorter range comparatively. Underwater Optical Wireless Communication (OWC) is mainly affected by the absorption and scattering of the optical signal. In coastal waters, both inherent and apparent optical properties (IOPs and AOPs) are influenced by a wide array of physical, biological and chemical processes leading to optical variability. The scattering effect has two effects: the attenuation of the signal and the Inter-Symbol Interference (ISI) of the signal. However, the Inter-Symbol Interference is ignored in the present paper. Therefore, in order to have an efficient underwater OWC link it is necessary to model the channel efficiently. In this paper, the underwater optical channel is modeled using Monte-Carlo method. The Monte Carlo approach provides the most general and most flexible technique for numerically solving the equations of Radiative transfer. The attenuation co-efficient of the light signal is studied as a function of the absorption (a) and scattering (b) coefficients. It has been observed that for pure sea water and for less chlorophyll conditions blue wavelength is less absorbed whereas for chlorophyll rich environment red wavelength signal is absorbed less comparative to blue and green wavelength.

  2. Hydrogel microphones for stealthy underwater listening

    Science.gov (United States)

    Gao, Yang; Song, Jingfeng; Li, Shumin; Elowsky, Christian; Zhou, You; Ducharme, Stephen; Chen, Yong Mei; Zhou, Qin; Tan, Li

    2016-08-01

    Exploring the abundant resources in the ocean requires underwater acoustic detectors with a high-sensitivity reception of low-frequency sound from greater distances and zero reflections. Here we address both challenges by integrating an easily deformable network of metal nanoparticles in a hydrogel matrix for use as a cavity-free microphone. Since metal nanoparticles can be densely implanted as inclusions, and can even be arranged in coherent arrays, this microphone can detect static loads and air breezes from different angles, as well as underwater acoustic signals from 20 Hz to 3 kHz at amplitudes as low as 4 Pa. Unlike dielectric capacitors or cavity-based microphones that respond to stimuli by deforming the device in thickness directions, this hydrogel device responds with a transient modulation of electric double layers, resulting in an extraordinary sensitivity (217 nF kPa-1 or 24 μC N-1 at a bias of 1.0 V) without using any signal amplification tools.

  3. OFDM for underwater acoustic communications

    CERN Document Server

    Zhou, Shengli

    2014-01-01

    A blend of introductory material and advanced signal processing and communication techniques, of critical importance to underwater system and network development This book, which is the first to describe the processing techniques central to underwater OFDM, is arranged into four distinct sections: First, it describes the characteristics of underwater acoustic channels, and stresses the difference from wireless radio channels. Then it goes over the basics of OFDM and channel coding. The second part starts with an overview of the OFDM receiver, and develops various modules for the receiver des

  4. Hemispherical optical dome for underwater communication

    Science.gov (United States)

    Shiri, Ron S.; Lunde, Emily L.; Coronado, Patrick L.; Quijada, Manuel A.

    2017-08-01

    For many years, acoustic systems have been used as the primary method for underwater communication; however, the data transfer rate of such systems is low because sound propagates slowly through water. A higher throughput can be achieved using visible light to transmit data underwater. The first issue with this approach is that there is generally a large loss of the light signal due to scattering and absorption in water, even though there is an optimal wavelength for transmission in the blue or green wavelengths of the visible spectrum. The second issue is that a simple communication system, consisting only of a highly directional source/transmitter and small optical detector/receiver, has a very narrow field of view. The goal of this project is to improve an optical, underwater communication system by increasing the effective field of view of the receiving optics. To this end, we make two changes to the simple system: (1) An optical dome was added near the receiver. An array of lenses is placed radially on the surface of the dome, reminiscent of the compound eye of an insect. The lenses make the source and detector planes conjugate, and each lens adds a new region of the source plane to the instrument's total field of view. (2) The receiver was expanded to include multiple photodiodes. With these two changes, the receiver has much more tolerance to misalignments (in position and angle) of the transmitter. Two versions of the optical dome (with 6" and 8" diameters) were designed using PTC's Creo CAD software and modeled using Synopsys' CODE V optical design software. A series of these transparent hemispherical domes, with both design diameters, were manufactured using a 5-axis mill. The prototype was then retrofitted with lenses and compared with the computer-generated model to demonstrate the effectiveness of this solution. This work shows that the dome design improves the optical field of view of the underwater communication system considerably. Furthermore, with

  5. Design and Analysis of an Underwater White LED Fish-Attracting Lamp and its Light Propagation

    Directory of Open Access Journals (Sweden)

    Sheng Chih Shen

    2013-03-01

    Full Text Available Light emitting diodes (LED are a new source for replacing traditional light sources including under water illumination. As traditional underwater light sources operate under a radiative transfer model, the luminous intensity is dispersed evenly at each emission angle, with the scattering factors included in the attenuation coefficient. By contrast, LED light sources are characterized by being highly directional, causing underwater luminous energy to vary with different emission angles. Thus, the traditional theory of underwater optical transfer becomes inapplicable when an underwater LED lighting module is designed. Therefore, to construct an underwater transfer model for LED light sources, this study employed the average cosine of the underwater light field, the method for light scattering probability, the LED luminous intensity distribution curve (LIDC and axial luminous intensity. Afterwards, an underwater LED fish-attracting lamp was designed. Experimental results showed that, compared with the simulation values, the luminous intensity of the underwater LED lighting module at all emission angles had a percentage error of less than 10%.

  6. Foley Sounds vs Real Sounds

    DEFF Research Database (Denmark)

    Trento, Stefano; Götzen, Amalia De

    2011-01-01

    This paper is an initial attempt to study the world of sound effects for motion pictures, also known as Foley sounds. Throughout several audio and audio-video tests we have compared both Foley and real sounds originated by an identical action. The main purpose was to evaluate if sound effects are...... applications of sound design such as advertisement or soundtracks for movies....

  7. Underwater soundscape of marine protected areas in the south Brazilian coast.

    Science.gov (United States)

    Sánchez-Gendriz, I; Padovese, L R

    2016-04-15

    The Laje de Santos Marine State Park (LSMSP) and Xixová-Japuí State Park (XJSP) are two protected areas (PA), close to the Santos Bay in the south Brazilian coast. The region encompasses both important biodiversity and anthropogenic activities. This study aims to serve as a first reference survey of the underwater soundscape of these PAs. Additionally it evaluates the presence of the anthropogenic and biological sound in these areas. One month of continuous recorded underwater sound, at selected locations in XJSP and LSMSP, is used in this study. The data were characterized by its spectral content and by the temporal evolution of Sound Pressure Levels (SPL). Both locations showed sound events with daily periodicities, mainly related with boats and fish chorus. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Discovery of Sound in the Sea 2014 Annual Report

    Science.gov (United States)

    2014-09-30

    a false killer whale was able to reduce its hearing sensitivity when a warning sound preceded a loud sound. The DOSITS team will continue to scan...will investigate noise exposure and marine animals, highlighting hearing sensititivies across taxa, potential behavioral effects of underwater sound...bottlenose whales , and dugongs are in development for the DOSITS Audio Gallery. In addition, longer audio files continue to be added when possible. B

  9. Underwater plasma arc cutting

    International Nuclear Information System (INIS)

    Leautier, R.; Pilot, G.

    1991-01-01

    This report describes the work done to develop underwater plasma arc cutting techniques, to characterise aerosols from cutting operations on radioactive and non-radioactive work-pieces, and to develop suitable ventilation and filtration techniques. The work has been carried out in the framework of a contract between CEA-CEN Cadarache and the Commission of European Communities. Furthermore, this work has been carried out in close cooperation with CEA-CEN Saclay mainly for secondary emissions and radioactive analysis. The contract started in May 1986 and was completed in December 1988 by a supplementary agreement. This report has been compiled from several progress reports submitted during the work period, contains the main findings of the work and encloses the results of comparative tests on plasma arc cutting

  10. Safety aspects for underwater vehicles

    Digital Repository Service at National Institute of Oceanography (India)

    Madhan, R.; Navelkar, G.S.; Desa, E.S.; Afzulpurkar, S.; Prabhudesai, S.P.; Dabholkar, N.; Mascarenhas, A.A.M.Q.; Maurya, P.

    . This stresses for implementation of multiple safety measures of a high degree so that the platform operates continuously in a fail-safe mode. This paper discusses issues on safety measures implemented on the autonomous underwater platforms namely MAYA AUV...

  11. Wide-band underwater acoustic absorption based on locally resonant unit and interpenetrating network structure

    International Nuclear Information System (INIS)

    Heng, Jiang; Mi-Lin, Zhang; Yu-Ren, Wang; Yan-Ping, Hu; Ding, Lan; Qun-Li, Wu; Huan-Tong, Lu

    2010-01-01

    The interpenetrating network structure provides an interesting avenue to novel materials. Locally resonant phononic crystal (LRPC) exhibits excellent sound attenuation performance based on the periodical arrangement of sound wave scatters. Combining the LRPC concept and interpenetrating network glassy structure, this paper has developed a new material which can achieve a wide band underwater strong acoustic absorption. Underwater absorption coefficients of different samples were measured by the pulse tube. Measurement results show that the new material possesses excellent underwater acoustic effects in a wide frequency range. Moreover, in order to investigate impacts of locally resonant units, some defects are introduced into the sample. The experimental result and the theoretical calculation both show that locally resonant units being connected to a network structure play an important role in achieving a wide band strong acoustic absorption. (condensed matter: structure, thermal and mechanical properties)

  12. Underwater optical wireless communication network

    Science.gov (United States)

    Arnon, Shlomi

    2010-01-01

    The growing need for underwater observation and subsea monitoring systems has stimulated considerable interest in advancing the enabling technologies of underwater wireless communication and underwater sensor networks. This communication technology is expected to play an important role in investigating climate change, in monitoring biological, biogeochemical, evolutionary, and ecological changes in the sea, ocean, and lake environments, and in helping to control and maintain oil production facilities and harbors using unmanned underwater vehicles (UUVs), submarines, ships, buoys, and divers. However, the present technology of underwater acoustic communication cannot provide the high data rate required to investigate and monitor these environments and facilities. Optical wireless communication has been proposed as the best alternative to meet this challenge. Models are presented for three kinds of optical wireless communication links: (a) a line-of-sight link, (b) a modulating retroreflector link, and (c) a reflective link, all of which can provide the required data rate. We analyze the link performance based on these models. From the analysis, it is clear that as the water absorption increases, the communication performance decreases dramatically for the three link types. However, by using the scattered light it was possible to mitigate this decrease in some cases. It is concluded from the analysis that a high-data-rate underwater optical wireless network is a feasible solution for emerging applications such as UUV-to-UUV links and networks of sensors, and extended ranges in these applications could be achieved by applying a multi-hop concept.

  13. Evaluation of moving-coil loudspeaker and passive radiator parameters using normal-incidence sound transmission measurements: theoretical developments.

    Science.gov (United States)

    Leishman, Timothy W; Anderson, Brian E

    2013-07-01

    The parameters of moving-coil loudspeaker drivers are typically determined using direct electrical excitation and measurement. However, as electro-mechano-acoustical devices, their parameters should also follow from suitable mechanical or acoustical evaluations. This paper presents the theory of an acoustical method of excitation and measurement using normal-incidence sound transmission through a baffled driver as a plane-wave tube partition. Analogous circuits enable key parameters to be extracted from measurement results in terms of open and closed-circuit driver conditions. Associated tools are presented that facilitate adjacent field decompositions and derivations of sound transmission coefficients (in terms of driver parameters) directly from the circuits. The paper also clarifies the impact of nonanechoic receiving tube terminations and the specific benefits of downstream field decompositions.

  14. Game Theory-Based Cooperation for Underwater Acoustic Sensor Networks: Taxonomy, Review, Research Challenges and Directions

    Directory of Open Access Journals (Sweden)

    Dalhatu Muhammed

    2018-02-01

    Full Text Available Exploring and monitoring the underwater world using underwater sensors is drawing a lot of attention these days. In this field cooperation between acoustic sensor nodes has been a critical problem due to the challenging features such as acoustic channel failure (sound signal, long propagation delay of acoustic signal, limited bandwidth and loss of connectivity. There are several proposed methods to improve cooperation between the nodes by incorporating information/game theory in the node’s cooperation. However, there is a need to classify the existing works and demonstrate their performance in addressing the cooperation issue. In this paper, we have conducted a review to investigate various factors affecting cooperation in underwater acoustic sensor networks. We study various cooperation techniques used for underwater acoustic sensor networks from different perspectives, with a concentration on communication reliability, energy consumption, and security and present a taxonomy for underwater cooperation. Moreover, we further review how the game theory can be applied to make the nodes cooperate with each other. We further analyze different cooperative game methods, where their performance on different metrics is compared. Finally, open issues and future research direction in underwater acoustic sensor networks are highlighted.

  15. Game Theory-Based Cooperation for Underwater Acoustic Sensor Networks: Taxonomy, Review, Research Challenges and Directions.

    Science.gov (United States)

    Muhammed, Dalhatu; Anisi, Mohammad Hossein; Zareei, Mahdi; Vargas-Rosales, Cesar; Khan, Anwar

    2018-02-01

    Exploring and monitoring the underwater world using underwater sensors is drawing a lot of attention these days. In this field cooperation between acoustic sensor nodes has been a critical problem due to the challenging features such as acoustic channel failure (sound signal), long propagation delay of acoustic signal, limited bandwidth and loss of connectivity. There are several proposed methods to improve cooperation between the nodes by incorporating information/game theory in the node's cooperation. However, there is a need to classify the existing works and demonstrate their performance in addressing the cooperation issue. In this paper, we have conducted a review to investigate various factors affecting cooperation in underwater acoustic sensor networks. We study various cooperation techniques used for underwater acoustic sensor networks from different perspectives, with a concentration on communication reliability, energy consumption, and security and present a taxonomy for underwater cooperation. Moreover, we further review how the game theory can be applied to make the nodes cooperate with each other. We further analyze different cooperative game methods, where their performance on different metrics is compared. Finally, open issues and future research direction in underwater acoustic sensor networks are highlighted.

  16. Adaptive Control of Sound Radiation from a Plate into an Acoustic Cavity Using Active Piezoelectric-Damping Composites

    National Research Council Canada - National Science Library

    Poh, S

    1999-01-01

    ... and noise control systems. The evaluation process will involve monitoring the vibration and noise radiation of these systems using a scanning laser vibrometer system to be acquired through this DURIP program...

  17. Design of Autonomous Underwater Vehicle

    Directory of Open Access Journals (Sweden)

    Tadahiro Hyakudome

    2011-03-01

    Full Text Available There are concerns about the impact that global warming will have on our environment, and which will inevitably result in expanding deserts and rising water levels. While a lot of underwater vehicles are utilized, AUVs (Autonomous Underwater Vehicle were considered and chosen, as the most suitable tool for conduction survey concerning these global environmental problems. AUVs can comprehensive survey because the vehicle does not have to be connected to the support vessel by tether cable. When such underwater vehicles are made, it is necessary to consider about the following things. 1 Seawater and Water Pressure Environment, 2 Sink, 3 There are no Gas or Battery Charge Stations, 4 Global Positioning System cannot use, 5 Radio waves cannot use. In the paper, outline of above and how deal about it are explained.

  18. Remote Underwater Characterization System - Innovative Technology Summary Report

    International Nuclear Information System (INIS)

    Willis, W.D.

    1999-01-01

    Characterization and inspection of water-cooled and moderated nuclear reactors and fuel storage pools requires equipment capable of operating underwater. Similarly, the deactivation and decommissioning of older nuclear facilities often requires the facility owner to accurately characterize underwater structures and equipment which may have been sitting idle for years. The Remote Underwater Characterization System (RUCS) is a small, remotely operated submersible vehicle intended to serve multiple purposes in underwater nuclear operations. It is based on the commercially-available Scallop vehicle 1 , but has been modified by the Department of Energys Robotics Technology Development Program to add auto-depth control, and vehicle orientation and depth monitoring at the operator control panel. The RUCS is designed to provide visual and gamma radiation characterization, even in confined or limited access areas. It was demonstrated in August 1998 at the Idaho National Engineering and Environmental Laboratory (INEEL) as part of the INEEL Large Scale Demonstration and Deployment Project. During the demonstration it was compared in a ''head-to-head fashion with the baseline characterization technology. This paper summarizes the results of the demonstration and lessons learned; comparing and contrasting both technologies in the areas of cost, visual characterization, radiological characterization, and overall operations

  19. Bioacoustic Spectral Whistle Sound And Behaviour Of Male Dolphin Bottle Nose ( Tursiops aduncus) At Safari Park Indonesia, Cisarua Bogor

    OpenAIRE

    Muhamad Zainuddin Lubis; Sri Pujiyati; Totok Hestirianoto

    2016-01-01

    Whistle sound is generally used for echolocation purposes, while the sound of the blast-beat and whistles play a major role in internal and inter-group communication.The purpose of this research is to know the power spectral patterns and fluctuations in sound based on frequency and Power Spectral Density (PSD) of the sounds produced by dolphins and observing the position of dolphins , Noisy Time Domain (NTD) and behavior using underwater camera, and also comparing between time and sound spect...

  20. Interpreting underwater acoustic images of the upper ocean boundary layer

    International Nuclear Information System (INIS)

    Ulloa, Marco J

    2007-01-01

    A challenging task in physical studies of the upper ocean using underwater sound is the interpretation of high-resolution acoustic images. This paper covers a number of basic concepts necessary for undergraduate and postgraduate students to identify the most distinctive features of the images, providing a link with the acoustic signatures of physical processes occurring simultaneously beneath the surface of the sea. Sonars are so sensitive that they detected a new acoustic signature at the breaking of surface gravity waves in deep water, which resembles oblique motion-like vortices

  1. Averaging underwater noise levels for environmental assessment of shipping.

    Science.gov (United States)

    Merchant, Nathan D; Blondel, Philippe; Dakin, D Tom; Dorocicz, John

    2012-10-01

    Rising underwater noise levels from shipping have raised concerns regarding chronic impacts to marine fauna. However, there is a lack of consensus over how to average local shipping noise levels for environmental impact assessment. This paper addresses this issue using 110 days of continuous data recorded in the Strait of Georgia, Canada. Probability densities of ~10(7) 1-s samples in selected 1/3 octave bands were approximately stationary across one-month subsamples. Median and mode levels varied with averaging time. Mean sound pressure levels averaged in linear space, though susceptible to strong bias from outliers, are most relevant to cumulative impact assessment metrics.

  2. Underwater measurements of muon intensity

    Science.gov (United States)

    Fedorov, V. M.; Pustovetov, V. P.; Trubkin, Y. A.; Kirilenkov, A. V.

    1985-01-01

    Experimental measurements of cosmic ray muon intensity deep underwater aimed at determining a muon absorption curve are of considerable interest, as they allow to reproduce independently the muon energy spectrum at sea level. The comparison of the muon absorption curve in sea water with that in rock makes it possible to determine muon energy losses caused by nuclear interactions. The data available on muon absorption in water and that in rock are not equivalent. Underground measurements are numerous and have been carried out down to the depth of approx. 15km w.e., whereas underwater muon intensity have been measured twice and only down to approx. 3km deep.

  3. Breath sounds

    Science.gov (United States)

    ... described as moist, dry, fine, and coarse. Rhonchi. Sounds that resemble snoring. They occur when air is blocked or air flow becomes rough through the large airways. Stridor. Wheeze-like sound heard when a person breathes. Usually it is ...

  4. Imagining Sound

    DEFF Research Database (Denmark)

    Grimshaw, Mark; Garner, Tom Alexander

    2014-01-01

    We make the case in this essay that sound that is imagined is both a perception and as much a sound as that perceived through external stimulation. To argue this, we look at the evidence from auditory science, neuroscience, and philosophy, briefly present some new conceptual thinking on sound...... that accounts for this view, and then use this to look at what the future might hold in the context of imagining sound and developing technology....

  5. Changes in 63Hz third-octave band sound levels over 42 months recorded at four deep-ocean observatories

    NARCIS (Netherlands)

    Schaar, M. van der; Ainslie, M.A.; Robinson, S.P.; Prior, M.K.; André, M.

    2014-01-01

    The growing scientific and societal concerns about the effects of underwater sound on marine ecosystems have been recently recognised through the introduction of several international initiatives, like the International Quiet Ocean Experiment, aimed at measuring the environmental impact of ocean

  6. The development of the underwater inspection vehicles for nuclear power plants

    International Nuclear Information System (INIS)

    Mabuchi, Yasuhiro; Takahashi, Yoshinori; Suzuki, Masanori

    2003-01-01

    There are many underwater structures in the Nuclear Power Plants (NPPs), and due to high radiation and underwater condition it's very difficult to carry out inspections in these areas. Remotely Operated Vehicles (ROVs) equipped with some thrusters and a CCD camera, have been in use for underwater remote inspections for the structure. Because these conventional ROVs for nuclear power plants can't acquire stable images and/or do not have any tools except for a camera, they have been applied to the restricted inspection tasks for nuclear power plants. HITACHI has been developing several ROVs, which are equipped with some additional functions and devices, in order to improve the performance of the conventional ROVs. These ROVs have been applied to the real NPPs and have proven to be useful and effective in the underwater inspection in the NPPs. (author)

  7. An Underwater Color Image Quality Evaluation Metric.

    Science.gov (United States)

    Yang, Miao; Sowmya, Arcot

    2015-12-01

    Quality evaluation of underwater images is a key goal of underwater video image retrieval and intelligent processing. To date, no metric has been proposed for underwater color image quality evaluation (UCIQE). The special absorption and scattering characteristics of the water medium do not allow direct application of natural color image quality metrics especially to different underwater environments. In this paper, subjective testing for underwater image quality has been organized. The statistical distribution of the underwater image pixels in the CIELab color space related to subjective evaluation indicates the sharpness and colorful factors correlate well with subjective image quality perception. Based on these, a new UCIQE metric, which is a linear combination of chroma, saturation, and contrast, is proposed to quantify the non-uniform color cast, blurring, and low-contrast that characterize underwater engineering and monitoring images. Experiments are conducted to illustrate the performance of the proposed UCIQE metric and its capability to measure the underwater image enhancement results. They show that the proposed metric has comparable performance to the leading natural color image quality metrics and the underwater grayscale image quality metrics available in the literature, and can predict with higher accuracy the relative amount of degradation with similar image content in underwater environments. Importantly, UCIQE is a simple and fast solution for real-time underwater video processing. The effectiveness of the presented measure is also demonstrated by subjective evaluation. The results show better correlation between the UCIQE and the subjective mean opinion score.

  8. An Autonomous Underwater Recorder Based on a Single Board Computer

    Science.gov (United States)

    Caldas-Morgan, Manuel; Alvarez-Rosario, Alexander; Rodrigues Padovese, Linilson

    2015-01-01

    As industrial activities continue to grow on the Brazilian coast, underwater sound measurements are becoming of great scientific importance as they are essential to evaluate the impact of these activities on local ecosystems. In this context, the use of commercial underwater recorders is not always the most feasible alternative, due to their high cost and lack of flexibility. Design and construction of more affordable alternatives from scratch can become complex because it requires profound knowledge in areas such as electronics and low-level programming. With the aim of providing a solution; a well succeeded model of a highly flexible, low-cost alternative to commercial recorders was built based on a Raspberry Pi single board computer. A properly working prototype was assembled and it demonstrated adequate performance levels in all tested situations. The prototype was equipped with a power management module which was thoroughly evaluated. It is estimated that it will allow for great battery savings on long-term scheduled recordings. The underwater recording device was successfully deployed at selected locations along the Brazilian coast, where it adequately recorded animal and manmade acoustic events, among others. Although power consumption may not be as efficient as that of commercial and/or micro-processed solutions, the advantage offered by the proposed device is its high customizability, lower development time and inherently, its cost. PMID:26076479

  9. An Autonomous Underwater Recorder Based on a Single Board Computer.

    Science.gov (United States)

    Caldas-Morgan, Manuel; Alvarez-Rosario, Alexander; Rodrigues Padovese, Linilson

    2015-01-01

    As industrial activities continue to grow on the Brazilian coast, underwater sound measurements are becoming of great scientific importance as they are essential to evaluate the impact of these activities on local ecosystems. In this context, the use of commercial underwater recorders is not always the most feasible alternative, due to their high cost and lack of flexibility. Design and construction of more affordable alternatives from scratch can become complex because it requires profound knowledge in areas such as electronics and low-level programming. With the aim of providing a solution; a well succeeded model of a highly flexible, low-cost alternative to commercial recorders was built based on a Raspberry Pi single board computer. A properly working prototype was assembled and it demonstrated adequate performance levels in all tested situations. The prototype was equipped with a power management module which was thoroughly evaluated. It is estimated that it will allow for great battery savings on long-term scheduled recordings. The underwater recording device was successfully deployed at selected locations along the Brazilian coast, where it adequately recorded animal and manmade acoustic events, among others. Although power consumption may not be as efficient as that of commercial and/or micro-processed solutions, the advantage offered by the proposed device is its high customizability, lower development time and inherently, its cost.

  10. Fluid Sounds

    DEFF Research Database (Denmark)

    and in architectural design. Aesthetics, psychoacoustics, perception, and cognition are all present in this expanding field embracing such categories as soundscape composition, sound art, sonic art, sound design, sound studies and auditory culture. Of greatest significance to the overall field is the investigation...... of sound, site and the social, and how the spatial, the visual, and the bodily interact in sonic environments, how they are constructed and how they are entangled in other practices. With the Seismograf special issue Fluid Sounds, we bring this knowledge into the dissemination of audio research itself...

  11. Underwater nuclear power plant structure

    International Nuclear Information System (INIS)

    Severs, S.; Toll, H.V.

    1982-01-01

    A structure for an underwater nuclear power generating plant comprising a triangular platform formed of tubular leg and truss members upon which are attached one or more large spherical pressure vessels and one or more small cylindrical auxiliary pressure vessels. (author)

  12. Underwater Robots Surface in Utah

    Science.gov (United States)

    Hurd, Randy C.; Hacking, Kip S.; Damarjian, Jennifer L.; Wright, Geoffrey A.; Truscott, Tadd

    2015-01-01

    Underwater robots (or ROVs: Remotely Operated Vehicles as they are typically called in industry) have recently become a very popular instructional STEM activity. Nationally, ROVs have been used in science and technology classrooms for several years in cities such as Seattle, San Diego, Virginia Beach, and other coastal areas. In the past two…

  13. A study on practical use of underwater abrasive water jet cutting

    Science.gov (United States)

    Yamaguchi, Hitoshi; Demura, Kenji

    1993-09-01

    The practicality of underwater abrasive water jet cutting technology was studied in experiments. A study of abrasives in slurried form showed that optimum polymer concentration can be selected to suit underwater conditions. For the long-distance transport of slurry from the ocean surface to the ocean floor, a direct supply system by hose proved to be practical. This system takes advantage of the insolubility of the slurry in water due to a difference in specific gravity. For cutting thick steel plate at great ocean depths, a simulation with a pressurized container revealed the requirements for actual cutting. Confirmation of remote cutting operations will become the most important technology in field applications. Underwater sound vibration characteristics were found to change significantly in direct response to modifications in cutting conditions. This will be important basic data to develop an effective sensoring method.

  14. Analysis of humpback whale sounds in shallow waters of the ...

    Indian Academy of Sciences (India)

    Acoustic parameters; breeding habitat; humpback whale; phrases; sound units; thematic structure. Published online: 27 April 2015 ... ed against a standard sensor at the underwater Acoustic Test. Facility of NIOT, which is the only ..... Landing Marine Laboratories, California State University. Papastavrou V 1995 Soviets ...

  15. Monte Carlo study on pulse response of underwater optical channel

    Science.gov (United States)

    Li, Jing; Ma, Yong; Zhou, Qunqun; Zhou, Bo; Wang, Hongyuan

    2012-06-01

    Pulse response of the underwater wireless optical channel is significant for the analysis of channel capacity and error probability. Traditional vector radiative transfer theory (VRT) is not able to deal with the effect of receiving aperture. On the other hand, general water tank experiments cannot acquire an accurate pulse response due to the limited time resolution of the photo-electronic detector. We present a Monte Carlo simulation model to extract the time-domain pulse response undersea. In comparison with the VRT model, a more accurate pulse response for practical ocean communications could be achieved through statistical analysis of the received photons. The proposed model is more reasonable for the study of the underwater optical channel.

  16. Sensitivity of a tucuxi (Sotalia fluviatilis guianensis) to airborne sound

    Science.gov (United States)

    Liebschner, Alexander; Hanke, Wolf; Miersch, Lars; Dehnhardt, Guido; Sauerland, Matthias

    2005-01-01

    Auditory systems of cetaceans are considered highly specialized for underwater sound processing, whereas the extent of their hearing capacity in air is still a point of issue. In this study, the sensitivity to airborne sound in a male tucuxi (Sotalia fluviatilis guianensis) was tested by means of a go/no go response paradigm. Auditory thresholds were obtained from 2 to 31.5 kHz. Compared to the hearing thresholds of other dolphins as well as of amphibian mammals, the sensitivity to airborne sound of the test subject is low from 2 to 8 kHz, with the highest threshold at 4 kHz. Thresholds at 16 and 31.5 kHz reveal a sharp increase in hearing sensitivity. Thus, although not obtained in this study, the upper aerial hearing limit is in the ultrasonic range. A comparison of the present data with the underwater audiogram of the same test subject referred to sound intensity indicates that the sensitivity of Sotalia to underwater sound is generally better than to airborne sound. .

  17. Unsound Sound

    DEFF Research Database (Denmark)

    Knakkergaard, Martin

    2016-01-01

    This article discusses the change in premise that digitally produced sound brings about and how digital technologies more generally have changed our relationship to the musical artifact, not simply in degree but in kind. It demonstrates how our acoustical conceptions are thoroughly challenged...... by the digital production of sound and, by questioning the ontological basis for digital sound, turns our understanding of the core term substance upside down....

  18. Autonomous docking control of visual-servo type underwater vehicle system aiming at underwater automatic charging

    International Nuclear Information System (INIS)

    Yanou, Akira; Ohnishi, Shota; Ishiyama, Shintaro; Minami, Mamoru

    2015-01-01

    A visual-servo type remotely operated vehicle (ROV) system with binocular wide-angle lens was developed to survey submarine resources, decontaminate radiation from mud in dam lake and so on. This paper explores the experiments on regulator performance and underwater docking of the robot system utilizing Genetic Algorithm (GA) for real-time recognition of the robot's relative position and posture through 3D marker. The visual servoing performances have been verified as follows; (1) The stability performances of the proposed regulator system have been evaluated by exerting abrupt distrubane force while the ROV is controlled by visual servoing. (2) The proposed system can track time-variant desired target position in x-axis (front-back direction of the robot). (3) The underwater docking can be completed by switching visual servoing and docking modes based on the error threshold, and by giving time-varying desired target position and orientation to the controller as a desired pose. (author)

  19. Sound Absorbers

    Science.gov (United States)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  20. The influence of environmental parameters on the optimal frequency in a shallow underwater acoustic channel

    Science.gov (United States)

    Zarnescu, George

    2015-02-01

    In a shallow underwater acoustic channel the delayed replicas of a transmitted signal are mainly due to the interactions with the sea surface and the bottom layer. If a specific underwater region on the globe is considered, for which the sedimentary layer structure is constant across the transmission distance, then the variability of the amplitude-delay profile is determined by daily and seasonal changes of the sound speed profile (SSP) and by weather changes, such as variations of the wind speed. Such a parameter will influence the attenuation at the surface, the noise level and the profile of the sea surface. The temporal variation of the impulse response in a shallow underwater acoustic channel determines the variability of the optimal transmission frequency. If the ways in which the optimal frequency changes can be predicted, then an adaptive analog transceiver can be easily designed for an underwater acoustic modem or it can be found when a communication link has high throughput. In this article it will be highlighted the way in which the amplitude-delay profile is affected by the sound speed profile, wind speed and channel depth and also will be emphasized the changes of the optimal transmission frequency in a configuration, where the transmitter and receiver are placed on the seafloor and the bathymetry profile will be considered flat, having a given composition.

  1. Interpolated Sounding and Gridded Sounding Value-Added Products

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, M. P. [Brookhaven National Laboratory (BNL), Upton, NY (United States); Toto, T. [Brookhaven National Laboratory (BNL), Upton, NY (United States)

    2016-03-01

    Standard Atmospheric Radiation Measurement (ARM) Climate Research Facility sounding files provide atmospheric state data in one dimension of increasing time and height per sonde launch. Many applications require a quick estimate of the atmospheric state at higher time resolution. The INTERPOLATEDSONDE (i.e., Interpolated Sounding) Value-Added Product (VAP) transforms sounding data into continuous daily files on a fixed time-height grid, at 1-minute time resolution, on 332 levels, from the surface up to a limit of approximately 40 km. The grid extends that high so the full height of soundings can be captured; however, most soundings terminate at an altitude between 25 and 30 km, above which no data is provided. Between soundings, the VAP linearly interpolates atmospheric state variables in time for each height level. In addition, INTERPOLATEDSONDE provides relative humidity scaled to microwave radiometer (MWR) observations.

  2. Network Computing for Distributed Underwater Acoustic Sensors

    Science.gov (United States)

    2014-03-31

    Physical layer in UASNs Our main investigations are about underwater communications using acoustic waves. Elec- tromagnetic and optical waves do not...Shengli, Z., and Jun-Hong, C. (2008), Prospects and problems of wireless communication for underwater sensor networks, Wirel. Commun . Mob. Comput., 8(8... Wireless Communications , 9(9), 2934–2944. [21] Pompili, D. and Akyildiz, I. (2010), A multimedia cross-layer protocol for underwater acoustic sensor networks

  3. Cooperative OFDM underwater acoustic communications

    CERN Document Server

    Cheng, Xilin; Cheng, Xiang

    2016-01-01

    Following underwater acoustic channel modeling, this book investigates the relationship between coherence time and transmission distances. It considers the power allocation issues of two typical transmission scenarios, namely short-range transmission and medium-long range transmission. For the former scenario, an adaptive system is developed based on instantaneous channel state information. The primary focus is on cooperative dual-hop orthogonal frequency division multiplexing (OFDM). This book includes the decomposed fountain codes designed to enable reliable communications with higher energy efficiency. It covers the Doppler Effect, which improves packet transmission reliability for effective low-complexity mirror-mapping-based intercarrier interference cancellation schemes capable of suppressing the intercarrier interference power level. Designed for professionals and researchers in the field of underwater acoustic communications, this book is also suitable for advanced-level students in electrical enginee...

  4. International Conference on Underwater Environment

    CERN Document Server

    Jaulin, Luc; Creuze, Vincent; Debese, Nathalie; Quidu, Isabelle; Clement, Benoît; Billon-Coat, Annick

    2016-01-01

    This volume constitutes the results of the International Conference on Underwater Environment, MOQESM’14, held at “Le Quartz” Conference Center in Brest, France, on October 14-15, 2014, within the framework of the 9th Sea Tech Week, International Marine Science and Technology Event. The objective of MOQESM'14 was to bring together researchers from both academia and industry, interested in marine robotics and hydrography with application to the coastal environment mapping and underwater infrastructures surveys. The common thread of the conference is the combination of technical control, perception, and localization, typically used in robotics, with the methods of mapping and bathymetry. The papers presented in this book focus on two main topics. Firstly, coastal and infrastructure mapping is addressed, focusing not only on hydrographic systems, but also on positioning systems, bathymetry, and remote sensing. The proposed methods rely on acoustic sensors such as side scan sonars, multibeam echo sounders, ...

  5. Radiation

    International Nuclear Information System (INIS)

    2013-01-01

    The chapter one presents the composition of matter and atomic theory; matter structure; transitions; origin of radiation; radioactivity; nuclear radiation; interactions in decay processes; radiation produced by the interaction of radiation with matter

  6. Sound generator

    NARCIS (Netherlands)

    Berkhoff, Arthur P.

    2008-01-01

    A sound generator, particularly a loudspeaker, configured to emit sound, comprising a rigid element (2) enclosing a plurality of air compartments (3), wherein the rigid element (2) has a back side (B) comprising apertures (4), and a front side (F) that is closed, wherein the generator is provided

  7. Sound generator

    NARCIS (Netherlands)

    Berkhoff, Arthur P.

    2010-01-01

    A sound generator, particularly a loudspeaker, configured to emit sound, comprising a rigid element (2) enclosing a plurality of air compartments (3), wherein the rigid element (2) has a back side (B) comprising apertures (4), and a front side (F) that is closed, wherein the generator is provided

  8. Sound generator

    NARCIS (Netherlands)

    Berkhoff, Arthur P.

    2007-01-01

    A sound generator, particularly a loudspeaker, configured to emit sound, comprising a rigid element (2) enclosing a plurality of air compartments (3), wherein the rigid element (2) has a back side (B) comprising apertures (4), and a front side (F) that is closed, wherein the generator is provided

  9. Sound knowledge

    DEFF Research Database (Denmark)

    Kauffmann, Lene Teglhus

    of the research is to investigate what is considered to ‘work as evidence’ in health promotion and how the ‘evidence discourse’ influences social practices in policymaking and in research. From investigating knowledge practices in the field of health promotion, I develop the concept of sound knowledge...... making, which I call ‘sound knowledge’. Sound knowledge is an approach to knowledge that takes the reflexive considerations of actors in policymaking processes as well as in research about what knowledge is into account. Seeing knowledge as sound makes connections between different ideas, concepts...... and ideologies explicit. Furthermore, in relation to an anthropology of knowledge, sound knowledge also offers a reconsideration of the way anthropologists study knowledge, as it specifies that studying knowledge for anthropologists means studying what people consider as knowledge, in what circumstances...

  10. Underwater versus dry irradiation with 60Co, a qualitative analysis

    International Nuclear Information System (INIS)

    Omi, Nelson M.; Rela, Paulo R.

    2007-01-01

    The development of gemstone gamma irradiation devices showed that underwater irradiation leads to better results than the irradiation in dry condition. Many reasons may be shown for that behavior. This work intends to analyze qualitatively two of these reasons. The medium discontinuity between the irradiation source, gemstone, and the air inside the irradiation devices, which is minimized in underwater irradiation, is one of them. The other analyzed hypothesis is the differences between the interactions of source's direct radiation and those from the scattered radiation. The numerical study of these hypothesis, as long as some irradiation tests may be presented in future works. The main conclusion of this work is that the absorbed dose may have different behavior view if the depending on the kind and energy level of the absorbed dose. For example, it is not used to consider what portion of the dose is due to source's direct hit, what part is from ejected electrons with high or low energy and how much high, medium and low energy electro-magnetic quanta hit a portion of mass when determining its radiation dose. To know the total absorbed dose is usually, but not always, enough to explain a material response to radiation. (author)

  11. Modelling techniques for underwater noise generated by tidal turbines in shallow water

    OpenAIRE

    Lloyd, Thomas P.; Turnock, Stephen R.; Humphrey, Victor F.

    2011-01-01

    The modelling of underwater noise sources and their potential impact on the marine environment is considered, focusing on tidal turbines in shallow water. The requirement for device noise prediction as part of environmental impact assessment is outlined and the limited amount of measurement data and modelling research identified. Following the identification of potential noise sources, the dominant flowgenerated sources are modelled using empirical techniques. The predicted sound pressure lev...

  12. Array Receivers and Sound Sources for Three Dimensional Shallow Water Acoustic Field Experiments

    Science.gov (United States)

    2016-12-06

    great success. Our acoustics research groups, the Ocean Acoustics and Signals Laboratory and the Acoustic Communications Group, in the Applied Ocean...field efforts in shallow-water acoustics and underwater acoustic communications. We have plans to upgrade our existing hydrophone arrays and sound...Hydrophone Receiver Unit) arrays. The immedate objective was to improve our fieldwork capibility and to enhance the quality of our underwater acoustic

  13. Sound exposure changes European seabass behaviour in a large outdoor floating pen: Effects of temporal structure and a ramp-up procedure

    NARCIS (Netherlands)

    Neo, Y.Y.; Hubert, J.; Bolle, L.J.; Winter, Hendrik V.; Cate, ten C.; Slabbekoorn, H.

    2016-01-01

    Underwater sound from human activities may affect fish behaviour negatively and threaten the stability of fish stocks. However, some fundamental understanding is still lacking for adequate impact assessments and potential mitigation strategies. For example, little is known about the potential

  14. Novel underwater soundscape: acoustic repertoire of plainfin midshipman fish.

    Science.gov (United States)

    McIver, Eileen L; Marchaterre, Margaret A; Rice, Aaron N; Bass, Andrew H

    2014-07-01

    Toadfishes are among the best-known groups of sound-producing (vocal) fishes and include species commonly known as toadfish and midshipman. Although midshipman have been the subject of extensive investigation of the neural mechanisms of vocalization, this is the first comprehensive, quantitative analysis of the spectro-temporal characters of their acoustic signals and one of the few for fishes in general. Field recordings of territorial, nest-guarding male midshipman during the breeding season identified a diverse vocal repertoire composed of three basic sound types that varied widely in duration, harmonic structure and degree of amplitude modulation (AM): 'hum', 'grunt' and 'growl'. Hum duration varied nearly 1000-fold, lasting for minutes at a time, with stable harmonic stacks and little envelope modulation throughout the sound. By contrast, grunts were brief, ~30-140 ms, broadband signals produced both in isolation and repetitively as a train of up to 200 at intervals of ~0.5-1.0 s. Growls were also produced alone or repetitively, but at variable intervals of the order of seconds with durations between those of grunts and hums, ranging 60-fold from ~200 ms to 12 s. Growls exhibited prominent harmonics with sudden shifts in pulse repetition rate and highly variable AM patterns, unlike the nearly constant AM of grunt trains and flat envelope of hums. Behavioral and neurophysiological studies support the hypothesis that each sound type's unique acoustic signature contributes to signal recognition mechanisms. Nocturnal production of these sounds against a background chorus dominated constantly for hours by a single sound type, the multi-harmonic hum, reveals a novel underwater soundscape for fish. © 2014. Published by The Company of Biologists Ltd.

  15. Sound Zones

    DEFF Research Database (Denmark)

    Møller, Martin Bo; Olsen, Martin

    2017-01-01

    Sound zones, i.e. spatially confined regions of individual audio content, can be created by appropriate filtering of the desired audio signals reproduced by an array of loudspeakers. The challenge of designing filters for sound zones is twofold: First, the filtered responses should generate...... an acoustic separation between the control regions. Secondly, the pre- and post-ringing as well as spectral deterioration introduced by the filters should be minimized. The tradeoff between acoustic separation and filter ringing is the focus of this paper. A weighted L2-norm penalty is introduced in the sound...

  16. Metasurface for Water-to-Air Sound Transmission

    Science.gov (United States)

    Bok, Eun; Park, Jong Jin; Choi, Haejin; Han, Chung Kyu; Wright, Oliver B.; Lee, Sam H.

    2018-01-01

    Effective transmission of sound from water to air is crucial for the enhancement of the detection sensitivity of underwater sound. However, only 0.1% of the acoustic energy is naturally transmitted at such a boundary. At audio frequencies, quarter-wave plates or multilayered antireflection coatings are too bulky for practical use for such enhancement. Here we present an acoustic metasurface of a thickness of only ˜λ /100 , where λ is the wavelength in air, consisting of an array of meta-atoms that each contain a set of membranes and an air-filled cavity. We experimentally demonstrate that such a meta-atom increases the transmission of sound at ˜700 Hz by 2 orders of magnitude, allowing about 30% of the incident acoustic power from water to be transmitted into air. Applications include underwater sonic sensing and communication.

  17. An Underwater Robot for the Maintenance of Nuclear Power Plants

    International Nuclear Information System (INIS)

    Lee, Sung-Uk; Choi, Young-Soo; Jeong, Kyung-Min

    2007-01-01

    The safety and reliability of nuclear power plants has become more important than in the past. Inspection and maintenance of a component should be achieved continuously. Two reactor types PWR (Pressurized Water Reactor) and PHWR (Pressurized Heavy Water Reactor) are normally operated in Korea. In the case of a PWR, the presence of any loose part affects the safety of a nuclear power plant. A loose part, which could be from failed components or an item inadvertently left during a construction, refueling or maintenance like as metallic parts, bolts, nuts and washers, can damage any part by frequently impacting that part in the system. Therefore, work that detects a loose part and removes it from a the nuclear reactor vessel is very important. Moreover, the inspection of the RCS (reactor coolant system) of PWR is also important. The RCS has a role to cool down the reactor's temperature. But human workers can't access the RCS easily because of the complexity of the path and the radiation level. So a robotic system is needed to inspect the RCS closely. Research on an underwater robot for an inspection of a nuclear reactor vessel began in the 1990s. Since then, many underwater robots for a nuclear power plant have been developed. But the developed underwater robots were so heavy and also they only had one function that is to inspect the nuclear reactor vessel. In this paper, an underwater robotic system is developed for inspecting the bottom of the nuclear reactor vessel, hot legs and cold legs of reactor coolant system and also for removing some particles in them

  18. An Underwater Robot for the Maintenance of Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sung-Uk; Choi, Young-Soo; Jeong, Kyung-Min [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2007-07-01

    The safety and reliability of nuclear power plants has become more important than in the past. Inspection and maintenance of a component should be achieved continuously. Two reactor types PWR (Pressurized Water Reactor) and PHWR (Pressurized Heavy Water Reactor) are normally operated in Korea. In the case of a PWR, the presence of any loose part affects the safety of a nuclear power plant. A loose part, which could be from failed components or an item inadvertently left during a construction, refueling or maintenance like as metallic parts, bolts, nuts and washers, can damage any part by frequently impacting that part in the system. Therefore, work that detects a loose part and removes it from a the nuclear reactor vessel is very important. Moreover, the inspection of the RCS (reactor coolant system) of PWR is also important. The RCS has a role to cool down the reactor's temperature. But human workers can't access the RCS easily because of the complexity of the path and the radiation level. So a robotic system is needed to inspect the RCS closely. Research on an underwater robot for an inspection of a nuclear reactor vessel began in the 1990s. Since then, many underwater robots for a nuclear power plant have been developed. But the developed underwater robots were so heavy and also they only had one function that is to inspect the nuclear reactor vessel. In this paper, an underwater robotic system is developed for inspecting the bottom of the nuclear reactor vessel, hot legs and cold legs of reactor coolant system and also for removing some particles in them.

  19. Radiation acoustics

    CERN Document Server

    Lyamshev, Leonid M

    2004-01-01

    Radiation acoustics is a developing field lying at the intersection of acoustics, high-energy physics, nuclear physics, and condensed matter physics. Radiation Acoustics is among the first books to address this promising field of study, and the first to collect all of the most significant results achieved since research in this area began in earnest in the 1970s.The book begins by reviewing the data on elementary particles, absorption of penetrating radiation in a substance, and the mechanisms of acoustic radiation excitation. The next seven chapters present a theoretical treatment of thermoradiation sound generation in condensed media under the action of modulated penetrating radiation and radiation pulses. The author explores particular features of the acoustic fields of moving thermoradiation sound sources, sound excitation by single high-energy particles, and the efficiency and optimal conditions of thermoradiation sound generation. Experimental results follow the theoretical discussions, and these clearl...

  20. Sound intensity

    DEFF Research Database (Denmark)

    Crocker, Malcolm J.; Jacobsen, Finn

    1998-01-01

    This chapter is an overview, intended for readers with no special knowledge about this particular topic. The chapter deals with all aspects of sound intensity and its measurement from the fundamental theoretical background to practical applications of the measurement technique.......This chapter is an overview, intended for readers with no special knowledge about this particular topic. The chapter deals with all aspects of sound intensity and its measurement from the fundamental theoretical background to practical applications of the measurement technique....

  1. Sound Intensity

    DEFF Research Database (Denmark)

    Crocker, M.J.; Jacobsen, Finn

    1997-01-01

    This chapter is an overview, intended for readers with no special knowledge about this particular topic. The chapter deals with all aspects of sound intensity and its measurement from the fundamental theoretical background to practical applications of the measurement technique.......This chapter is an overview, intended for readers with no special knowledge about this particular topic. The chapter deals with all aspects of sound intensity and its measurement from the fundamental theoretical background to practical applications of the measurement technique....

  2. Upgrade of ROV Super GNOME Pro for Underwater Monitoring in the Caspian Sea

    Science.gov (United States)

    Rozman, B. Ya.; Elkin, A. V.; Kaptsov, A. S.; Ermakov, I. D.; Ermakov, D. I.; Krasnov, V. G.; Kondrashov, L. S.

    2018-01-01

    A description and characteristics of the small-size remotely operated underwater vehicle Super GNOME pro are given. The main technical innovations and upgrades of the vehicle are considered along with the reasons and aims of these improvements. The innovations were evaluated during expedition work in northern Caspian Sea in 2016, which demonstrated good results. Further upgrades include installation of a sediment-penetrating thermometer for measuring the thermal background of benthonic soil and an underwater dosimeter/radiometer for assessing the radiation background of water areas.

  3. Synchronous and Rhythmic Vocalizations and Correlated Underwater Behavior of Free-ranging Atlantic Spotted Dolphins (Stenella frontalis and Bottlenose Dolphins (Tursiops truncatus in the Bahamas

    Directory of Open Access Journals (Sweden)

    Denise L. Herzing

    2015-02-01

    Full Text Available Since 1985 a resident community of Atlantic spotted dolphins (Stenella frontalis, and bottlenose dolphins (Tursiops truncatus, have been studied underwater in the Bahamas. Over 200 individuals of both species have been identified and observed over the years. Basic correlations with sound patterns and behavior such as whistles during contact/reunions and squawks during aggression have been reported. This paper describes a small subset of their vocal repertoire that involves synchronous/rhythmic sound production. Dolphin behavior was recorded underwater using underwater video cameras with hydrophone input. Vocalizations were correlated with basic underwater behavioral activity and analyzed using Raven 1.3. Spotted dolphins were observed using two types of synchronized vocalizations including synchronized squawks (burst pulsed vocalizations and screams- (overlapping FM whistles during intraspecific and interspecific aggression. Bottlenose dolphins used three types of synchronized vocalizations; whistles/buzz bouts, bray/buzz bouts, and buzz bouts during intraspecific aggression. Body postures were synchronous with physical movements and often mirrored the rhythm of the vocalizations. The intervals between highly synchronized vocalizations had small variance and created a rhythmic quality and cadence to the acoustic sequences. Three types of vocalizations had similar ratios of sound duration to the spacing between sounds (Screams, whistle/buzz bouts, and bray/buzz bouts. Temporal aspects of sequences of sound and postures may be important aspects of individual and group coordination and behavior in delphinids.

  4. Underwater inspection by immersion phased array UT technique

    International Nuclear Information System (INIS)

    Hirasawa, Taiji

    2017-01-01

    In the inspection during the service period of a nuclear power plant, ultrasonic flaw detection test (UT) is performed as a volume test to confirm the soundness of the equipment and structure. Phased array UT technology has been applied as a technique to measure with high accuracy the crack depth generated in stainless steel or Ni based alloy welds. This paper picked up main scanning methods based on ultrasonic beam control in phased array UT, as well as items to consider when carrying out underwater UT inspection of reactor internal structure, and described the concept of selection method of flaw detection method. As the example of underwater UT inspection, this paper introduced application examples for actual equipment and test body, in the defect depth measurement of water immersion phased array UT, by choosing reactor internal structures etc. of a BWR plant. The core shroud, core spray piping, jet pump, CRD housing, and shroud support of BWR plant that are introduced here are subject to individual inspection under maintenance standards and are extremely important equipment. (A.O.)

  5. Underwater noise pollution in a coastal tropical environment.

    Science.gov (United States)

    Bittencourt, L; Carvalho, R R; Lailson-Brito, J; Azevedo, A F

    2014-06-15

    Underwater noise pollution has become a major concern in marine habitats. Guanabara Bay, southeastern Brazil, is an impacted area of economic importance with constant vessel traffic. One hundred acoustic recording sessions took place over ten locations. Sound sources operating within 1 km radius of each location were quantified during recordings. The highest mean sound pressure level near the surface was 111.56±9.0 dB re 1 μPa at the frequency band of 187 Hz. Above 15 kHz, the highest mean sound pressure level was 76.21±8.3 dB re 1 μPa at the frequency 15.89 kHz. Noise levels correlated with number of operating vessels and vessel traffic composition influenced noise profiles. Shipping locations had the highest noise levels, while small vessels locations had the lowest noise levels. Guanabara Bay showed noise pollution similar to that of other impacted coastal regions, which is related to shipping and vessel traffic. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Model based image restoration for underwater images

    Science.gov (United States)

    Stephan, Thomas; Frühberger, Peter; Werling, Stefan; Heizmann, Michael

    2013-04-01

    The inspection of offshore parks, dam walls and other infrastructure under water is expensive and time consuming, because such constructions must be inspected manually by divers. Underwater buildings have to be examined visually to find small cracks, spallings or other deficiencies. Automation of underwater inspection depends on established water-proved imaging systems. Most underwater imaging systems are based on acoustic sensors (sonar). The disadvantage of such an acoustic system is the loss of the complete visual impression. All information embedded in texture and surface reflectance gets lost. Therefore acoustic sensors are mostly insufficient for these kind of visual inspection tasks. Imaging systems based on optical sensors feature an enormous potential for underwater applications. The bandwidth from visual imaging systems reach from inspection of underwater buildings via marine biological applications through to exploration of the seafloor. The reason for the lack of established optical systems for underwater inspection tasks lies in technical difficulties of underwater image acquisition and processing. Lightening, highly degraded images make a computational postprocessing absolutely essential.

  7. Application of an Underwater Robot in Reactor Coolant System

    International Nuclear Information System (INIS)

    Choi, Young-Soo; Jeong, Kyung-Min; Lee, Sung-Uk; Cho, Jai-Wan

    2006-01-01

    Nuclear energy is a major source of electric energy consumed in Korea. It has the advantage of other energy sources, nuclear energy is cost effective and little pollution. But the fearfulness of an accident and/or failure has scared us the utilization of nuclear energy extensively. So, the safety and reliability of nuclear power plants become more important. Inspection and maintenance of component should be achieved continuously. The RCS(reactor coolant system) of PWR(pressurized water reactor) has a role to cool down the reactor's temperature. Cooling water is injected through the SI(safety injection) nozzle into the cold leg of the primary loop. Thermal sleeves are attached inside the cylindrical SI nozzle to reduce the thermal shock of the cooling water to the weld zone of the safety injection nozzle. The human workers are susceptible to radiation exposure and manual handling machine is hard to access because of the complexity of the path. So, we developed and applied free running, tele-operated underwater vehicle to inspect SI nozzle close to the place. Tele-operated robot is useful to inspect and maintain the component of nuclear power plants to reduce the radiation exposure of human operators and improve the reliability of the operation in nuclear power plants. Underwater robot is comprised of two parts; one is robot vehicle and the other is remote control module. Underwater robot vehicle has 4 DOF(degree of freedom) of mobility and 1 DOF of camera observation. The task to inspect the internal of RCS in nuclear power plant is achieved successfully. And the reliability for the maintenance is increased by the aid of tele-operated robot

  8. Application of an Underwater Robot in Reactor Coolant System

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Young-Soo; Jeong, Kyung-Min; Lee, Sung-Uk; Cho, Jai-Wan [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2006-07-01

    Nuclear energy is a major source of electric energy consumed in Korea. It has the advantage of other energy sources, nuclear energy is cost effective and little pollution. But the fearfulness of an accident and/or failure has scared us the utilization of nuclear energy extensively. So, the safety and reliability of nuclear power plants become more important. Inspection and maintenance of component should be achieved continuously. The RCS(reactor coolant system) of PWR(pressurized water reactor) has a role to cool down the reactor's temperature. Cooling water is injected through the SI(safety injection) nozzle into the cold leg of the primary loop. Thermal sleeves are attached inside the cylindrical SI nozzle to reduce the thermal shock of the cooling water to the weld zone of the safety injection nozzle. The human workers are susceptible to radiation exposure and manual handling machine is hard to access because of the complexity of the path. So, we developed and applied free running, tele-operated underwater vehicle to inspect SI nozzle close to the place. Tele-operated robot is useful to inspect and maintain the component of nuclear power plants to reduce the radiation exposure of human operators and improve the reliability of the operation in nuclear power plants. Underwater robot is comprised of two parts; one is robot vehicle and the other is remote control module. Underwater robot vehicle has 4 DOF(degree of freedom) of mobility and 1 DOF of camera observation. The task to inspect the internal of RCS in nuclear power plant is achieved successfully. And the reliability for the maintenance is increased by the aid of tele-operated robot.

  9. Interpolated Sounding and Gridded Sounding Value-Added Products

    Energy Technology Data Exchange (ETDEWEB)

    Toto, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Jensen, M. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-03-01

    Standard Atmospheric Radiation Measurement (ARM) Climate Research Facility sounding files provide atmospheric state data in one dimension of increasing time and height per sonde launch. Many applications require a quick estimate of the atmospheric state at higher time resolution. The INTERPOLATEDSONDE (i.e., Interpolated Sounding) Value-Added Product (VAP) transforms sounding data into continuous daily files on a fixed time-height grid, at 1-minute time resolution, on 332 levels, from the surface up to a limit of approximately 40 km. The grid extends that high so the full height of soundings can be captured; however, most soundings terminate at an altitude between 25 and 30 km, above which no data is provided. Between soundings, the VAP linearly interpolates atmospheric state variables in time for each height level. In addition, INTERPOLATEDSONDE provides relative humidity scaled to microwave radiometer (MWR) observations.The INTERPOLATEDSONDE VAP, a continuous time-height grid of relative humidity-corrected sounding data, is intended to provide input to higher-order products, such as the Merged Soundings (MERGESONDE; Troyan 2012) VAP, which extends INTERPOLATEDSONDE by incorporating model data. The INTERPOLATEDSONDE VAP also is used to correct gaseous attenuation of radar reflectivity in products such as the KAZRCOR VAP.

  10. Sound settlements

    DEFF Research Database (Denmark)

    Duelund Mortensen, Peder

    2013-01-01

    Præsentation af projektresultater fra Interreg forskningen Sound Settlements om udvikling af bæredygtighed i det almene boligbyggerier i København, Malmø, Helsingborg og Lund samt europæiske eksempler på best practice......Præsentation af projektresultater fra Interreg forskningen Sound Settlements om udvikling af bæredygtighed i det almene boligbyggerier i København, Malmø, Helsingborg og Lund samt europæiske eksempler på best practice...

  11. Sound Settlements

    DEFF Research Database (Denmark)

    Mortensen, Peder Duelund; Hornyanszky, Elisabeth Dalholm; Larsen, Jacob Norvig

    2013-01-01

    Præsentation af projektresultater fra Interreg forskningen Sound Settlements om udvikling af bæredygtighed i det almene boligbyggerier i København, Malmø, Helsingborg og Lund samt europæiske eksempler på best practice......Præsentation af projektresultater fra Interreg forskningen Sound Settlements om udvikling af bæredygtighed i det almene boligbyggerier i København, Malmø, Helsingborg og Lund samt europæiske eksempler på best practice...

  12. A new technique for robot vision in autonomous underwater vehicles using the color shift in underwater imaging

    Science.gov (United States)

    2017-06-01

    FOR ROBOT VISION IN AUTONOMOUS UNDERWATER VEHICLES USING THE COLOR SHIFT IN UNDERWATER IMAGING by Jake A. Jones June 2017 Thesis Advisor... VEHICLES USING THE COLOR SHIFT IN UNDERWATER IMAGING 5. FUNDING NUMBERS 6. AUTHOR(S) Jake A. Jones 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS...underwater vehicles (AUVs), robot vision, autonomy, visual odometry, underwater color shift, optical properties of water 15. NUMBER OF PAGES 75 16

  13. Microstructural characterizations and mechanical properties in underwater friction stir welding of aluminum and magnesium dissimilar alloys

    International Nuclear Information System (INIS)

    Zhao, Yong; Lu, Zhengping; Yan, Keng; Huang, Linzhao

    2015-01-01

    Highlights: • Aluminum and magnesium alloys were joined by underwater friction stir welding. • Underwater FSW was conducted to improve properties of joint with lower heat input. • Microstructures and mechanical properties of dissimilar joint were investigated. • Intermetallic compounds developed in the fracture interface were analyzed. • Fracture features of the tensile samples were analyzed. - Abstract: Formation of intermetallic compounds in the stir zone of dissimilar welds affects the mechanical properties of the joints significantly. In order to reduce heat input and control the amount and morphological characteristics of brittle intermetallic compounds underwater friction stir welding of 6013 Al alloy and AZ31 Mg alloy was carried out. Microstructures, mechanical properties, elements distribution, and the fracture surface of the joints were analyzed by optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, etc. The result shows that sound dissimilar joint with good mechanical properties can be obtained by underwater friction stir welding. Al and Mg alloys were stirred together and undergone the process of recrystallization, forming complex intercalated flow patterns in the stir zone. Tensile strength of the dissimilar joint was up to 152.3 MPa. Maximum hardness (142HV) appeared in the middle of the centerline of the specimen. Intermetallic compounds layer consisting of Al 3 Mg 2 and Mg 17 Al 12 formed in the Al/Mg interface and resulted in the fracture of the joint

  14. Corrosion Resistant Cladding by YAG Laser Welding in Underwater Environment

    International Nuclear Information System (INIS)

    Tsutomi Kochi; Toshio Kojima; Suemi Hirata; Ichiro Morita; Katsura Ohwaki

    2002-01-01

    It is known that stress-corrosion cracking (SCC) will occur in nickel-base alloys used in Reactor Pressure Vessel (RPV) and Internals of nuclear power plants. A SCC sensitivity has been evaluated by IHI in each part of RPV and Internals. There are several water level instrumentation nozzles installed in domestic BWR RPV. In water level instrumentation nozzles, 182 type nickel-base alloys were used for the welding joint to RPV. It is estimated the SCC potential is high in this joint because of a higher residual stress than the yield strength (about 400 MPa). This report will describe a preventive maintenance method to these nozzles Heat Affected Zone (HAZ) and welds by a corrosion resistant cladding (CRC) by YAG Laser in underwater environment (without draining a reactor water). There are many kinds of countermeasures for SCC, for example, Induction Heating Stress Improvement (IHSI), Mechanical Stress Improvement Process (MSIP) and so on. A YAG laser CRC is one of them. In this technology a laser beam is used for heat source and irradiated through an optical fiber to a base metal and SCC resistant material is used for welding wires. After cladding the HAZ and welds are coated by the corrosion resistant materials so their surfaces are improved. A CRC by gas tungsten arc welding (GTAW) in an air environment had been developed and already applied to a couple of operating plants (16 Nozzles). This method was of course good but it spent much time to perform because of an installation of some water-proof working boxes to make a TIG-weldability environment. CRC by YAG laser welding in underwater environment has superior features comparing to this conventional TIG method as follows. At the viewpoint of underwater environment, (1) an outage term reduction (no drainage water). (2) a radioactive exposure dose reduction for personnel. At that of YAG laser welding, (1) A narrower HAZ. (2) A smaller distortion. (3) A few cladding layers. A YAG laser CRC test in underwater

  15. Second Sound

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 6. Second Sound - The Role of Elastic Waves. R Srinivasan. General Article Volume 4 Issue 6 June 1999 pp 15-19. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/004/06/0015-0019 ...

  16. Second Sound

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 3. Second Sound - Waves of Entropy and Temperature. R Srinivasan. General Article Volume 4 Issue 3 March 1999 pp 16-24. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/004/03/0016-0024 ...

  17. Second Sound

    Indian Academy of Sciences (India)

    as a function of q is called adispersion curve. Landau postulated. R Srinivasan is a Visiting. Professor at the Raman. Research Institute after retiring as .... Second sound was seen in solid 4He crystals by Ackermann and others in 1966. 4He will not solidify even at absolute zero of temperature unless one applies a pressure ...

  18. Second Sound

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 6. Second Sound - The Role of Elastic Waves. R Srinivasan. General Article Volume 4 Issue 6 June 1999 pp 15-19. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/004/06/0015-0019 ...

  19. Sound engineer

    CERN Document Server

    Mara, Wil

    2015-01-01

    "Readers will learn what it takes to succeed as a sound engineer. The book also explains the necessary educational steps, useful character traits, potential hazards, and daily job tasks related to this career. Sidebars include thought-provoking trivia. Questions in the backmatter ask for text-dependent analysis. Photos, a glossary, and additional resources are included."-- Provided by publisher.

  20. Sound Settlements

    DEFF Research Database (Denmark)

    Mortensen, Peder Duelund; Hornyanszky, Elisabeth Dalholm; Larsen, Jacob Norvig

    2013-01-01

    Præsentation af projektresultater fra Interreg forskningen Sound Settlements om udvikling af bæredygtighed i det almene boligbyggerier i København, Malmø, Helsingborg og Lund samt europæiske eksempler på best practice...

  1. Jellyfish inspired underwater unmanned vehicle

    Science.gov (United States)

    Villanueva, Alex; Bresser, Scott; Chung, Sanghun; Tadesse, Yonas; Priya, Shashank

    2009-03-01

    An unmanned underwater vehicle (UUV) was designed inspired by the form and functionality of a Jellyfish. These natural organisms were chosen as bio-inspiration for a multitude of reasons including: efficiency of locomotion, lack of natural predators, proper form and shape to incorporate payload, and varying range of sizes. The structure consists of a hub body surrounded by bell segments and microcontroller based drive system. The locomotion of UUV was achieved by shape memory alloy "Biometal Fiber" actuation which possesses large strain and blocking force with adequate response time. The main criterion in design of UUV was the use of low-profile shape memory alloy actuators which act as artificial muscles. In this manuscript, we discuss the design of two Jellyfish prototypes and present experimental results illustrating the performance and power consumption.

  2. Underwater sympathetic detonation of pellet explosive

    Science.gov (United States)

    Kubota, Shiro; Saburi, Tei; Nagayama, Kunihito

    2017-06-01

    The underwater sympathetic detonation of pellet explosives was taken by high-speed photography. The diameter and the thickness of the pellet were 20 and 10 mm, respectively. The experimental system consists of the precise electric detonator, two grams of composition C4 booster and three pellets, and these were set in water tank. High-speed video camera, HPV-X made by Shimadzu was used with 10 Mfs. The underwater explosions of the precise electric detonator, the C4 booster and a pellet were also taken by high-speed photography to estimate the propagation processes of the underwater shock waves. Numerical simulation of the underwater sympathetic detonation of the pellet explosives was also carried out and compared with experiment.

  3. Underwater Grass Comeback Helps Chesapeake Bay

    Science.gov (United States)

    The fortified Susquehanna Flats, the largest bed of underwater grasses in the Chesapeake Bay, seems able to withstand a major weather punch. Its resilience is contributing to an overall increase in the Bay’s submerged aquatic vegetation.

  4. Underwater Object Segmentation Based on Optical Features

    Directory of Open Access Journals (Sweden)

    Zhe Chen

    2018-01-01

    Full Text Available Underwater optical environments are seriously affected by various optical inputs, such as artificial light, sky light, and ambient scattered light. The latter two can block underwater object segmentation tasks, since they inhibit the emergence of objects of interest and distort image information, while artificial light can contribute to segmentation. Artificial light often focuses on the object of interest, and, therefore, we can initially identify the region of target objects if the collimation of artificial light is recognized. Based on this concept, we propose an optical feature extraction, calculation, and decision method to identify the collimated region of artificial light as a candidate object region. Then, the second phase employs a level set method to segment the objects of interest within the candidate region. This two-phase structure largely removes background noise and highlights the outline of underwater objects. We test the performance of the method with diverse underwater datasets, demonstrating that it outperforms previous methods.

  5. Sensor network architectures for monitoring underwater pipelines.

    Science.gov (United States)

    Mohamed, Nader; Jawhar, Imad; Al-Jaroodi, Jameela; Zhang, Liren

    2011-01-01

    This paper develops and compares different sensor network architecture designs that can be used for monitoring underwater pipeline infrastructures. These architectures are underwater wired sensor networks, underwater acoustic wireless sensor networks, RF (radio frequency) wireless sensor networks, integrated wired/acoustic wireless sensor networks, and integrated wired/RF wireless sensor networks. The paper also discusses the reliability challenges and enhancement approaches for these network architectures. The reliability evaluation, characteristics, advantages, and disadvantages among these architectures are discussed and compared. Three reliability factors are used for the discussion and comparison: the network connectivity, the continuity of power supply for the network, and the physical network security. In addition, the paper also develops and evaluates a hierarchical sensor network framework for underwater pipeline monitoring.

  6. Underwater photogrammetry successful in Spain and France

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    Underwater photogrammetry has been used to measure distortions in fuel assembly alignment pins in the upper internals of the Almarez and Dampierre PWRs. Photogrammetry is a three-dimensional precision measurement method using photographic techniques for the on-site measurement phase. On the strength of the operations at the two PWRs, underwater photogrammetry is now considered as a practical and effective technique for dimensional inspection at nuclear plants. (U.K.)

  7. Underwater noise levels in UK waters

    OpenAIRE

    Merchant, Nathan D.; Brookes, Kate L.; Faulkner, Rebecca C.; Bicknell, Anthony W. J.; Godley, Brendan J.; Witt, Matthew J.

    2016-01-01

    Underwater noise from human activities appears to be rising, with ramifications for acoustically sensitive marine organisms and the functioning of marine ecosystems. Policymakers are beginning to address the risk of ecological impact, but are constrained by a lack of data on current and historic noise levels. Here, we present the first nationally coordinated effort to quantify underwater noise levels, in support of UK policy objectives under the EU Marine Strategy Framework Directive (MSFD). ...

  8. Underwater gait analysis in Parkinson's disease.

    Science.gov (United States)

    Volpe, Daniele; Pavan, Davide; Morris, Meg; Guiotto, Annamaria; Iansek, Robert; Fortuna, Sofia; Frazzitta, Giuseppe; Sawacha, Zimi

    2017-02-01

    Although hydrotherapy is one of the physical therapies adopted to optimize gait rehabilitation in people with Parkinson disease, the quantitative measurement of gait-related outcomes has not been provided yet. This work aims to document the gait improvements in a group of parkinsonians after a hydrotherapy program through 2D and 3D underwater and on land gait analysis. Thirty-four parkinsonians and twenty-two controls were enrolled, divided into two different cohorts. In the first one, 2 groups of patients underwent underwater or land based walking training; controls underwent underwater walking training. Hence pre-treatment 2D underwater and on land gait analysis were performed, together with post-treatment on land gait analysis. Considering that current literature documented a reduced movement amplitude in parkinsonians across all lower limb joints in all movement planes, 3D underwater and on land gait analysis were performed on a second cohort of subjects (10 parkinsonians and 10 controls) who underwent underwater gait training. Baseline land 2D and 3D gait analysis in parkinsonians showed shorter stride length and slower speed than controls, in agreement with previous findings. Comparison between underwater and on land gait analysis showed reduction in stride length, cadence and speed on both parkinsonians and controls. Although patients who underwent underwater treatment exhibited significant changes on spatiotemporal parameters and sagittal plane lower limb kinematics, 3D gait analysis documented a significant (p<0.05) improvement in all movement planes. These data deserve attention for research directions promoting the optimal recovery and maintenance of walking ability. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

  9. Affordable underwater wireless optical communication using LEDs

    Science.gov (United States)

    Pilipenko, Vladimir; Arnon, Shlomi

    2013-09-01

    In recent years the need for high data rate underwater wireless communication (WC) has increased. Nowadays, the conventional technology for underwater communication is acoustic. However, the maximum data rate that acoustic technology can provide is a few kilobits per second. On the other hand, emerging applications such as underwater imaging, networks of sensors and swarms of underwater vehicles require much faster data rates. As a result, underwater optical WC, which can provide much higher data rates, has been proposed as an alternative means of communication. In addition to high data rates, affordable communication systems become an important feature in the development requirements. The outcome of these requirements is a new system design based on off-the-shelf components such as blue and green light emitting diodes (LEDs). This is due to the fact that LEDs offer solutions characterized by low cost, high efficiency, reliability and compactness. However, there are some challenges to be met when incorporating LEDs as part of the optical transmitter, such as low modulation rates and non linearity. In this paper, we review the main challenges facing the incorporation of LEDs as an integral part of underwater WC systems and propose some techniques to mitigate the LED limitations in order to achieve high data rate communication

  10. An underwater optical wireless communication network

    Science.gov (United States)

    Arnon, Shlomi

    2009-08-01

    The growing need for underwater observation and sub-sea monitoring systems has stimulated considerable interest in advancing the enabling technologies of underwater wireless communication and underwater sensor networks. This communication technology is expected to play an important role in investigating climate change, in monitoring biological, bio-geochemical, evolutionary and ecological changes in the sea, ocean and lake environments and in helping to control and maintain oil production facilities and harbors using unmanned underwater vehicles (UUVs), submarines, ships, buoys, and divers. However, the present technology of underwater acoustic communication cannot provide the high data rate required to investigate and monitor these environments and facilities. Optical wireless communication has been proposed as the best alternative to meet this challenge. We present models of three kinds of optical wireless communication links a) a line-of-sight link, b) a modulating retro-reflector link and c) a reflective link, all of which can provide the required data rate. We analyze the link performance based on these models. From the analysis, it is clear that as the water absorption increases, the communication performance decreases dramatically for the three link types. However, by using the scattered lighted it was possible to mitigate this decrease in some cases. We conclude from the analysis that a high data rate underwater optical wireless network is a feasible solution for emerging applications such as UUV to UUV links and networks of sensors, and extended ranges in these applications could be achieved by applying a multi-hop concept.

  11. PREFACE: Aerodynamic sound Aerodynamic sound

    Science.gov (United States)

    Akishita, Sadao

    2010-02-01

    The modern theory of aerodynamic sound originates from Lighthill's two papers in 1952 and 1954, as is well known. I have heard that Lighthill was motivated in writing the papers by the jet-noise emitted by the newly commercialized jet-engined airplanes at that time. The technology of aerodynamic sound is destined for environmental problems. Therefore the theory should always be applied to newly emerged public nuisances. This issue of Fluid Dynamics Research (FDR) reflects problems of environmental sound in present Japanese technology. The Japanese community studying aerodynamic sound has held an annual symposium since 29 years ago when the late Professor S Kotake and Professor S Kaji of Teikyo University organized the symposium. Most of the Japanese authors in this issue are members of the annual symposium. I should note the contribution of the two professors cited above in establishing the Japanese community of aerodynamic sound research. It is my pleasure to present the publication in this issue of ten papers discussed at the annual symposium. I would like to express many thanks to the Editorial Board of FDR for giving us the chance to contribute these papers. We have a review paper by T Suzuki on the study of jet noise, which continues to be important nowadays, and is expected to reform the theoretical model of generating mechanisms. Professor M S Howe and R S McGowan contribute an analytical paper, a valuable study in today's fluid dynamics research. They apply hydrodynamics to solve the compressible flow generated in the vocal cords of the human body. Experimental study continues to be the main methodology in aerodynamic sound, and it is expected to explore new horizons. H Fujita's study on the Aeolian tone provides a new viewpoint on major, longstanding sound problems. The paper by M Nishimura and T Goto on textile fabrics describes new technology for the effective reduction of bluff-body noise. The paper by T Sueki et al also reports new technology for the

  12. Development of underwater inspection and YAG laser repair welding robots for equipments

    International Nuclear Information System (INIS)

    Sato, Shuichi; Kojima, Toshio; Ohwaki, Katsura; Hirose, Naoya

    2000-01-01

    As equipments for power generation such as tank on bath storing wasted water, used resin and others in mainly radioactive wastes processing equipments in nuclear power plant and so forth are carried out periodical inspections and repairs to keep their soundness from long years ago, its importance seems to be increasing more and more hereafter at background of a trend of longer life in their plant. In response to such importance, development of technologies capable of remote control on inspection of inside of the equipments at underwater atmosphere and on repair welding due to YAG laser have been carried out. Here were described on necessity in remote inspection and repair technique, outlines on remote underwater inspection and repair technique, results on welding test, items on compatibility test, and their concrete examples. (G.K.)

  13. State of the art report: Underwater examination techniques for spent nuclear fuels

    International Nuclear Information System (INIS)

    Chun, Yong Bum

    1997-06-01

    In these days, much efforts are being put to increase the final discharge burnup of PWR fuels. Therefore, the necessity of the inspection of irradiated nuclear fuels assembly during the the refueling outage is greatly increased to evaluate the safe operation and soundness of fuel assemblies in their next cycles in core, and apply the results for safe operation and effective core management. The necessity to evaluate the irradiation performance of indigenous nuclear fuels pushes the relative researchers to the development of on-site fuel inspection techniques and devices which can perform the underwater inspection and measurement of irradiated nuclear fuels during refueling outage. To ensure the technologies, the status of in situ underwater fuel inspection techniques and equipment were investigated and reviewed. Those information provides the fuel inspection capability to evaluate and certificate the performance and integrity of nuclear fuels which leads to the safe operation of NPP. (author). 49 refs., 52 figs

  14. Characterizing large river sounds: Providing context for understanding the environmental effects of noise produced by hydrokinetic turbines.

    Science.gov (United States)

    Bevelhimer, Mark S; Deng, Z Daniel; Scherelis, Constantin

    2016-01-01

    Underwater noise associated with the installation and operation of hydrokinetic turbines in rivers and tidal zones presents a potential environmental concern for fish and marine mammals. Comparing the spectral quality of sounds emitted by hydrokinetic turbines to natural and other anthropogenic sound sources is an initial step at understanding potential environmental impacts. Underwater recordings were obtained from passing vessels and natural underwater sound sources in static and flowing waters. Static water measurements were taken in a lake with minimal background noise. Flowing water measurements were taken at a previously proposed deployment site for hydrokinetic turbines on the Mississippi River, where sounds created by flowing water are part of all measurements, both natural ambient and anthropogenic sources. Vessel sizes ranged from a small fishing boat with 60 hp outboard motor to an 18-unit barge train being pushed upstream by tugboat. As expected, large vessels with large engines created the highest sound levels, which were, on average, 40 dB greater than the sound created by an operating hydrokinetic turbine. A comparison of sound levels from the same sources at different distances using both spherical and cylindrical sound attenuation functions suggests that spherical model results more closely approximate observed sound attenuation.

  15. A new signal development process and sound system for diverting fish from water intakes

    International Nuclear Information System (INIS)

    Klinet, D.A.; Loeffelman, P.H.; van Hassel, J.H.

    1992-01-01

    This paper reports that American Electric Power Service Corporation has explored the feasibility of using a patented signal development process and underwater sound system to divert fish away from water intake areas. The effect of water intakes on fish is being closely scrutinized as hydropower projects are re-licensed. The overall goal of this four-year research project was to develop an underwater guidance system which is biologically effective, reliable and cost-effective compared to other proposed methods of diversion, such as physical screens. Because different fish species have various listening ranges, it was essential to the success of this experiment that the sound system have a great amount of flexibility. Assuming a fish's sounds are heard by the same kind of fish, it was necessary to develop a procedure and acquire instrumentation to properly analyze the sounds that the target fish species create to communicate and any artificial signals being generated for diversion

  16. Underwater Noise Modeling in Lithuanian Area of the Baltic Sea

    Directory of Open Access Journals (Sweden)

    Donatas Bagočius

    2017-09-01

    Full Text Available Along with rising awareness of public and scientific societies about environmental and ecological impacts of underwater noise, the need for underwater noise modelling in the shallow Lithuanian area of Baltic Sea emerged. Marine Strategy Framework Directive issues regarding underwater noise indicators refers to possibility of evaluation of Good Environmental State using underwater noise measurements as well as possibility to model underwater noise. Main anthropogenic underwater noise contributor in the Seas is the shipping lanes as known due to date, with no exclusion of Lithuanian Baltic Sea area. In this manuscript, it is presented the methods of development of simplistic underwater ambient noise model purposed for computation of underwater soundscape in shallow area of the Lithuanian Baltic Sea.

  17. Underwater Sensor Networks: A New Energy Efficient and Robust Architecture

    NARCIS (Netherlands)

    Climent, Salvador; Capella, Juan Vincente; Meratnia, Nirvana; Serrano, Juan José

    2012-01-01

    The specific characteristics of underwater environments introduce new challenges for networking protocols. In this paper, a specialized architecture for underwater sensor networks (UWSNs) is proposed and evaluated. Experiments are conducted in order to analyze the suitability of this protocol for

  18. Magnetohydrodynamic underwater vehicular propulsion systems

    International Nuclear Information System (INIS)

    Swallom, D.W.; Sadovnik, I.; Gibbs, J.S.; Gurol, H.; Nguyen, L.

    1990-01-01

    The development of magnetohydrodynamic propulsion systems for underwater vehicles is discussed. According to the authors, it is a high risk endeavor that offers the possibility of a number of significant advantages over conventional propeller propulsion systems. These advantages may include the potential for greater stealth characteristics, increased maneuverability, enhanced survivability, elimination of cavitation limits, and addition of a significant emergency propulsion system. The possibility of increased stealth is by far the most important advantage. A conceptual design study has been completed with numerical results that shows that these advantages may be obtained with a magnetohydrodynamic propulsion system in an annular configuration externally surrounding a generic study submarine that is neutrally buoyant and can operate with the existing submarine propulsion system power plant. The classical submarine mission requirements make the use of these characteristics of the magnetohydrodynamic propulsion system particularly appropriate for submarine missions. The magnetohydrodynamic annular propulsion system for a generic attack class submarine has been designed to take advantage of the magnetohydrodynamic thruster characteristics

  19. Routing strategies for underwater gliders

    Science.gov (United States)

    Davis, Russ E.; Leonard, Naomi E.; Fratantoni, David M.

    2009-02-01

    Gliders are autonomous underwater vehicles that achieve long operating range by moving at speeds comparable to those of, or slower than, typical ocean currents. This paper addresses routing gliders to rapidly reach a specified waypoint or to maximize the ability to map a measured field, both in the presence of significant currents. For rapid transit in a frozen velocity field, direct minimization of travel time provides a trajectory "ray" equation. A simpler routing algorithm that requires less information is also discussed. Two approaches are developed to maximize the mapping ability, as measured by objective mapping error, of arrays of vehicles. In order to produce data sets that are readily interpretable, both approaches focus sampling near predetermined "ideal tracks" by measuring mapping skill only on those tracks, which are laid out with overall mapping skill in mind. One approach directly selects each vehicle's headings to maximize instantaneous mapping skill integrated over the entire array. Because mapping skill decreases when measurements are clustered, this method automatically coordinates glider arrays to maintain spacing. A simpler method that relies on manual control for array coordination employs a first-order control loop to balance staying close to the ideal track and maintaining vehicle speed to maximize mapping skill. While the various techniques discussed help in dealing with the slow speed of gliders, nothing can keep performance from being degraded when current speeds are comparable to vehicle speed. This suggests that glider utility could be greatly enhanced by the ability to operate high speeds for short periods when currents are strong.

  20. Impact of internal waves on sound propagation off Bhimilipatnam, east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Sridevi, B.; Murty, T.V.R.; Sadhuram, Y.; Rao, M.M.M.; Maneesha, K.; SujithKumar, S.; Prasanna, P.L.

    -259 Impact of internal waves on sound propagation off Bhimilipatnam, East coast of India B.Sridevi, T.V. Ramana Murty, Y. Sadhuram, M.M.M. Rao, K. Maneesha, S. Sujith Kumar and P.L. Prasanna National Institute of Oceanography, Regional center, 176... the variability of ocean environment rather than it’s mean. Oceanic changes relevant to underwater acoustics are classified into mean and fluctuating components (De Santo 1979) with the following general model of the sound velocity equation...

  1. Underwater Optics in Sub-Antarctic and Antarctic Coastal Ecosystems.

    Directory of Open Access Journals (Sweden)

    Pirjo Huovinen

    Full Text Available Understanding underwater optics in natural waters is essential in evaluating aquatic primary production and risk of UV exposure in aquatic habitats. Changing environmental conditions related with global climate change, which imply potential contrasting changes in underwater light climate further emphasize the need to gain insights into patterns related with underwater optics for more accurate future predictions. The present study evaluated penetration of solar radiation in six sub-Antarctic estuaries and fjords in Chilean North Patagonian region (39-44°S and in an Antarctic bay (62°S. Based on vertical diffuse attenuation coefficients (Kd, derived from measurements with a submersible multichannel radiometer, average summer UV penetration depth (z1% in these water bodies ranged 2-11 m for UV-B (313 nm, 4-27 m for UV-A (395 nm, and 7-30 m for PAR (euphotic zone. UV attenuation was strongest in the shallow Quempillén estuary, while Fildes Bay (Antarctica exhibited the highest transparency. Optically non-homogeneous water layers and seasonal variation in transparency (lower in winter characterized Comau Fjord and Puyuhuapi Channel. In general, multivariate analysis based on Kd values of UV and PAR wavelengths discriminated strongly Quempillén estuary and Puyuhuapi Channel from other study sites. Spatial (horizontal variation within the estuary of Valdivia river reflected stronger attenuation in zones receiving river impact, while within Fildes Bay a lower spatial variation in water transparency could in general be related to closeness of glaciers, likely due to increased turbidity through ice-driven processes. Higher transparency and deeper UV-B penetration in proportion to UV-A/visible wavelengths observed in Fildes Bay suggests a higher risk for Antarctic ecosystems reflected by e.g. altered UV-B damage vs. photorepair under UV-A/PAR. Considering that damage repair processes often slow down under cool temperatures, adverse UV impact could be

  2. Technique for estimating the sound power level radiated by pneumatic rock drills and the evaluation of a CSIR prototype rock drill with engineering noise controls

    CSIR Research Space (South Africa)

    Kovalchik, PG

    2009-05-01

    Full Text Available This report describes the procedure for the measurement and reporting of noise from portable pneumatic tools such as jackleg drills. The technique used in this research allows for the determination of the source A-weighted sound power levels...

  3. Insights into Optimal Soft Start and Shutdown Procedures for Stationary or Moving Sound Sources

    NARCIS (Netherlands)

    Ainslie, M.A.; Benda-Beckmann, A.M. von

    2012-01-01

    To reduce the risk of impact on marine life of underwater sound generated by anthropogenic activities (such as offshore construction, seismic surveys and sonar searches), various mitigation measures are often put in place. Two commonly adopted mitigation measures are the soft start (or "ramp-up" –

  4. Impact of Vessel Noise on Oyster Toadfish (Opsanus tau) Behavior and Implications for Underwater Noise Management

    Science.gov (United States)

    Krahforst, Cecilia S.

    Underwater noise and its impacts on marine life are growing management concerns. This dissertation considers both the ecological and social concerns of underwater noise, using the oyster toadfish (Opsanus tau) as a model species. Oyster toadfish call for mates using a boatwhistle sound, but increased ambient noise levels from vessels or other anthropogenic activities are likely to influence the ability of males to find mates. If increased ambient noise levels reduce fish fitness then underwater noise can impact socially valued ecosystem services (e.g. fisheries). The following ecological objectives of the impacts of underwater noise on oyster toadfish were investigated: (1) to determine how noise influences male calling behavior; (2) to assess how areas of high vessel activity ("noisy") and low vessel activity ("quiet") influence habitat utilization (fish standard length and occupancy rate); and (3) to discover if fitness (number of clutches and number of embryos per clutch) is lower in "noisy" compared with "quiet" sites. Field experiments were executed in "noisy" and "quiet" areas. Recorded calls by males in response to playback sounds (vessel, predator, and snapping shrimp sounds) and egg deposition by females ("noisy" vs. "quiet" sites) demonstrated that oyster toadfish are impacted by underwater noise. First, males decreased their call rates and called louder in response to increased ambient noise levels. Second, oyster toadfish selected nesting sites in areas with little or no inboard motorboat activity. Third, male oyster toadfish at "noisy" sites either had no egg clutches on their shelters or the number of embryos per clutch was significantly lower than in the "quiet" areas. Underwater noise and disturbance from vessels are influencing the fitness of the oyster toadfish. The social significance of the growing concerns regarding underwater noise was investigated by identifying dominant themes found within two types of texts: four recent underwater noise

  5. Investigation of solar noise impact on the performance of underwater wireless optical communication links

    OpenAIRE

    Hamza, Tasnim; Khalighi, Mohammad-ali; Bourennane, Salah; Leon, Pierre; Opderbecke, Jan

    2016-01-01

    We investigate the effect of environmental noise, caused by solar radiations under water, on the performance of underwater wireless optical communication (UWOC) systems. Presenting an analytical and generic model for this noise, we examine its impact on the link performance in terms of the bit error rate (BER). This study is conducted for different photo-detector types in the aim of highlighting practical limitations of establishing UWOC links in the presence of subsea solar noise. We show ho...

  6. Survivability design for a hybrid underwater vehicle

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Biao; Wu, Chao; Li, Xiang; Zhao, Qingkai; Ge, Tong [State Key Lab of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-03-10

    A novel hybrid underwater robotic vehicle (HROV) capable of working to the full ocean depth has been developed. The battery powered vehicle operates in two modes: operate as an untethered autonomous vehicle in autonomous underwater vehicle (AUV) mode and operate under remote control connected to the surface vessel by a lightweight, fiber optic tether in remotely operated vehicle (ROV) mode. Considering the hazardous underwater environment at the limiting depth and the hybrid operating modes, survivability has been placed on an equal level with the other design attributes of the HROV since the beginning of the project. This paper reports the survivability design elements for the HROV including basic vehicle design of integrated navigation and integrated communication, emergency recovery strategy, distributed architecture, redundant bus, dual battery package, emergency jettison system and self-repairing control system.

  7. Survivability design for a hybrid underwater vehicle

    International Nuclear Information System (INIS)

    Wang, Biao; Wu, Chao; Li, Xiang; Zhao, Qingkai; Ge, Tong

    2015-01-01

    A novel hybrid underwater robotic vehicle (HROV) capable of working to the full ocean depth has been developed. The battery powered vehicle operates in two modes: operate as an untethered autonomous vehicle in autonomous underwater vehicle (AUV) mode and operate under remote control connected to the surface vessel by a lightweight, fiber optic tether in remotely operated vehicle (ROV) mode. Considering the hazardous underwater environment at the limiting depth and the hybrid operating modes, survivability has been placed on an equal level with the other design attributes of the HROV since the beginning of the project. This paper reports the survivability design elements for the HROV including basic vehicle design of integrated navigation and integrated communication, emergency recovery strategy, distributed architecture, redundant bus, dual battery package, emergency jettison system and self-repairing control system

  8. Recent developments in underwater repair welding

    International Nuclear Information System (INIS)

    Offer, H.P.; Chapman, T.L.; Willis, E.R.; Maslakowski, J.; Van Diemen, P.; Smith, B.W.

    2001-01-01

    As nuclear plants age and reactor internal components begin to show increased evidence of age-related phenomena such as corrosion and fatigue, interest in the development of cost-effective mitigation and repair remedies grows. One technology currently receiving greater development and application program focus is underwater welding. Underwater welding, as used herein, is the application of weld metal to a substrate surface that is wet, but locally dry in the immediate area surrounding the welding torch. The locally dry environment is achieved by the use of a mechanical device that is specifically designed for water exclusion from the welding torch, surface to be welded, and the welding groove. This paper will explore recent developments in the use of underwater welding as a mitigation and repair technique. (author)

  9. Behavioural effects of exposure to underwater explosions in humpback whales (Megaptera novaeangliae)

    Energy Technology Data Exchange (ETDEWEB)

    Todd, S.; Lien, J.; Marques, F. [Memorial Univ. of Newfoundland, St. John`s, NF (Canada); Stevick, P. [College of the Atlantic, Bar Harbor, ME (United States); Ketten, D. [Harvard Univ., Cambridge, MA (United States). Medical School

    1996-09-01

    Findings of a study of high rate of entrapment in nets of humpback whales off the coast of northeastern Newfoundland in 1991-92 were reported. The entrapments took place in the southern portion of Trinity Bay, a site associated with construction operations, including explosions and drilling, that was assumed to have modified the underwater acoustic environment. Results indicated few behavioural reactions to detonations by the whales when measured in terms of decreased residency, overall movements, or general behaviour. However, there is tentative evidence that the increased entrapment rate may have been influenced by the long-term effects of exposure to abnormally high sound levels. 46 refs.

  10. Underwater Noise from a Wave Energy Converter Is Unlikely to Affect Marine Mammals

    OpenAIRE

    Tougaard, Jakob

    2015-01-01

    Underwater noise was recorded from the Wavestar wave energy converter; a full-scale hydraulic point absorber, placed on a jack-up rig on the Danish North Sea coast. Noise was recorded 25 m from the converter with an autonomous recording unit (10 Hz to 20 kHz bandwidth). Median sound pressure levels (Leq) in third-octave bands during operation of the converter were 106-109 dB re. 1 μPa in the range 125-250 Hz, 1-2 dB above ambient noise levels (statistically significant). Outside the range 125...

  11. Data-based depth estimation of an incoming autonomous underwater vehicle.

    Science.gov (United States)

    Yang, T C; Xu, Wen

    2016-10-01

    The data-based method for estimating the depth of a moving source is demonstrated experimentally for an incoming autonomous underwater vehicle traveling toward a vertical line array (VLA) of receivers at constant speed/depth. The method assumes no information on the sound-speed and bottom profile. Performing a wavenumber analysis of a narrowband signal for each hydrophone, the energy of the (modal) spectral peaks as a function of the receiver depth is used to estimate the depth of the source, traveling within the depth span of the VLA. This paper reviews the theory, discusses practical implementation issues, and presents the data analysis results.

  12. How Might We Assess and Manage the Effects of Underwater Noise on Populations of Marine Animals?

    Science.gov (United States)

    Tasker, Mark L

    2016-01-01

    The European Union Marine Strategy Framework Directive (MSFD) aims to achieve good environmental status (GES) in European seas by 2020. One of the features of GES is that underwater sound should not adversely affect the marine environment. Direct injury of marine life may occur, but a more pervasive effect is likely to be through the cumulative indirect effects on behavior. Assessing the significance of these effects on an ecosystem scale is difficult. If subsequent management of these effects is required, complex and challenging international decisions will be required.

  13. Transformation of second sound into surface waves in superfluid helium

    International Nuclear Information System (INIS)

    Khalatnikov, I.M.; Kolmakov, G.V.; Pokrovsky, V.L.

    1995-01-01

    The Hamiltonian theory of superfluid liquid with a free boundary is developed. Nonlinear amplitudes of parametric Cherenkov radiation of a surface wave by second sound and the inner decay of second sound waves are found. Threshold amplitudes of second sound waves for these two processes are determined. 4 refs

  14. Efficient Modelling Methodology for Reconfigurable Underwater Robots

    DEFF Research Database (Denmark)

    Nielsen, Mikkel Cornelius; Blanke, Mogens; Schjølberg, Ingrid

    2016-01-01

    This paper considers the challenge of applying reconfigurable robots in an underwater environment. The main result presented is the development of a model for a system comprised of N, possibly heterogeneous, robots dynamically connected to each other and moving with 6 Degrees of Freedom (DOF......). This paper presents an application of the Udwadia-Kalaba Equation for modelling the Reconfigurable Underwater Robots. The constraints developed to enforce the rigid connection between robots in the system is derived through restrictions on relative distances and orientations. To avoid singularities...... in the orientation and, thereby, allow the robots to undertake any relative configuration the attitude is represented in Euler parameters....

  15. Underwater laser cutting of metallic structures

    International Nuclear Information System (INIS)

    Alfille, J.P.; Schildknecht, J.; Ramaswami, V.S.

    1993-01-01

    In the frame of an european contract, the feasibility of the underwater cutting with a CO 2 laser power is studied. The aim of this work is the dismantling metallic structures of reactors pools. The paper analyzes the general concept of the experimental device, the underwater cutting head, the experimenting vessel, examples of cuttings in dismantling situation with a 500 W CO 2 laser, and examples of cuttings with a 5 kW CO 2 laser. (author). 2 refs., 9 figs., 2 tabs

  16. Underwater noise from offshore oil production vessels.

    Science.gov (United States)

    Erbe, Christine; McCauley, Robert; McPherson, Craig; Gavrilov, Alexander

    2013-06-01

    Underwater acoustic recordings of six Floating Production Storage and Offloading (FPSO) vessels moored off Western Australia are presented. Monopole source spectra were computed for use in environmental impact assessments of underwater noise. Given that operations on the FPSOs varied over the period of recording, and were sometimes unknown, the authors present a statistical approach to noise level estimation. No significant or consistent aspect dependence was found for the six FPSOs. Noise levels did not scale with FPSO size or power. The 5th, 50th (median), and 95th percentile source levels (broadband, 20 to 2500 Hz) were 188, 181, and 173 dB re 1 μPa @ 1 m, respectively.

  17. Halifax Sound Range Trials (DE0301, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Radiated sound measurements of vessels are important for monitoring the noise characteristics of fishing and research vessels. A vessel's radiated noise can have...

  18. Radiation

    International Nuclear Information System (INIS)

    Davidson, J.H.

    1986-01-01

    The basic facts about radiation are explained, along with some simple and natural ways of combating its ill-effects, based on ancient healing wisdom as well as the latest biochemical and technological research. Details are also given of the diet that saved thousands of lives in Nagasaki after the Atomic bomb attack. Special comment is made on the use of radiation for food processing. (U.K.)

  19. Sound Search Engine Concept

    DEFF Research Database (Denmark)

    2006-01-01

    Sound search is provided by the major search engines, however, indexing is text based, not sound based. We will establish a dedicated sound search services with based on sound feature indexing. The current demo shows the concept of the sound search engine. The first engine will be realased June...

  20. IVO develops a new repair technique for underwater sites. Viscous doughlike substance underwater cracks

    Energy Technology Data Exchange (ETDEWEB)

    Klingstedt, G.; Leisio, C. [ed.

    1998-07-01

    A viscous sealant is revolutionizing repair of the stone and concrete masonry of underwater dams, bridges and canals. There is now no need for expensive and time-consuming cofferdams, since a diver can extrude quick-setting mortar into underwater structures needing repair. This technique has worked well in recent years in various parts of Finland even in strongly flowing water. IVO experts are now starting to look more beyond the borders of Finland

  1. Sound field separation with sound pressure and particle velocity measurements

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn; Leclère, Quentin

    2012-01-01

    separation techniques make it possible to distinguish between outgoing and incoming waves from the two sides, and thus NAH can be applied. In this paper, a separation method based on the measurement of the particle velocity in two layers and another method based on the measurement of the pressure...... and the velocity in a single layer are proposed. The two methods use an equivalent source formulation with separate transfer matrices for the outgoing and incoming waves, so that the sound from the two sides of the array can be modeled independently. A weighting scheme is proposed to account for the distance......In conventional near-field acoustic holography (NAH) it is not possible to distinguish between sound from the two sides of the array, thus, it is a requirement that all the sources are confined to only one side and radiate into a free field. When this requirement cannot be fulfilled, sound field...

  2. Repairs on underwater spent fuel transfer buggy and review of other underwater facilities of Cirus rod cutting building

    International Nuclear Information System (INIS)

    Rao, D.V.H.; Ganeshan, P.; Khadilkar, M.G.

    1994-01-01

    Cirus rod cutting building is a pool of water in concrete unlined bays. This houses several equipment required for processing of spent fuel and other experimental assemblies. These have been in use for over three decades. Recently the fuel transfer buggy had a major breakdown and the repair involved elaborate planning preparation and special methods to ensure safe working condition and to minimise manrem consumption. This also provided an opportunity to assess the condition of other underwater components in radiation environment which were hitherto inaccessible. This paper highlights the repair work carried on buggy and also the effect of ageing on some of the equipment vis a vis the possibility of their life extension. (author). 7 figs

  3. On the sound absorption coefficient of porous asphalt pavements for oblique incident sound waves

    NARCIS (Netherlands)

    Bezemer-Krijnen, Marieke; Wijnant, Ysbrand H.; de Boer, Andries; Bekke, Dirk; Davy, J.; Don, Ch.; McMinn, T.; Dowsett, L.; Broner, N.; Burgess, M.

    2014-01-01

    A rolling tyre will radiate noise in all directions. However, conventional measurement techniques for the sound absorption of surfaces only give the absorption coefficient for normal incidence. In this paper, a measurement technique is described with which it is possible to perform in situ sound

  4. NASA Space Sounds API

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has released a series of space sounds via sound cloud. We have abstracted away some of the hassle in accessing these sounds, so that developers can play with...

  5. Underwater Advanced Time-Domain Electromagnetic System

    Science.gov (United States)

    2017-03-03

    sufficiently waterproofed ...................................................................... 20 Objective: Calibration method can be used both topside... additional background variability is observed at early times, as illustrated in Figure 15. The layout of this figure is the same as Figure 14. Now the...are discussed in the following sections and summarized in Table 5. Objective: System is sufficiently waterproofed The array remained underwater up to

  6. Underwater Adhesives Retrofit Pipelines with Advanced Sensors

    Science.gov (United States)

    2015-01-01

    Houston-based Astro Technology Inc. used a partnership with Johnson Space Center to pioneer an advanced fiber-optic monitoring system for offshore oil pipelines. The company's underwater adhesives allow it to retrofit older deepwater systems in order to measure pressure, temperature, strain, and flow properties, giving energy companies crucial data in real time and significantly decreasing the risk of a catastrophe.

  7. Detection of Underwater UXOs in Mud

    Science.gov (United States)

    2013-04-01

    2nd International Conference on Underwater Acoustic Measurements, Crete, Greece, 2007. 16 [10] P.T. Gough and D.W. Hawkins “Imaging algorithms...course. Runs 275 and 325 folla.v the same trad < and run 322 foUows a track on the opposite side of the swath. The LF SAS image of run 325 is shown

  8. Adaptive turbo equalization for underwater acoustic communication

    NARCIS (Netherlands)

    Cannelli, L; Leus, G.; Dol, H.S.; Walree, P.A. van

    2013-01-01

    In this paper a multiband transceiver designed for underwater channels is presented. Multi-branch filtering at the receiver is used to leverage the diversity offered by a multi-scale multi-lag scenario. The multi-branch bank of filters is constructed by estimating scale and delay coefficients

  9. Underwater noise generated by offshore pile driving

    NARCIS (Netherlands)

    Tsouvalas, A.

    2015-01-01

    Anthropogenic noise emission in the marine environment has always been an environmental issue of serious concern. In particular, the noise generated during the installation of foundation piles is considered to be one of the most significant sources of underwater noise pollution. This is mainly

  10. Evolution: Fossil Ears and Underwater Sonar.

    Science.gov (United States)

    Lambert, Olivier

    2016-08-22

    A key innovation in the history of whales was the evolution of a sonar system together with high-frequency hearing. Fossils of an archaic toothed whale's inner ear bones provide clues for a stepwise emergence of underwater echolocation ability. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Impacts of underwater noise on marine vertebrates

    NARCIS (Netherlands)

    Liebschner, Alexander; Seibel, Henrike; Teilmann, Jonas; Wittekind, Dietrich; Parmentier, Eric; Dähne, Michael; Dietz, Rune; Driver, Jörg; Elk, van Cornelis; Everaarts, Eligius; Findeisen, Henning; Kristensen, Jacob; Lehnert, Kristina; Lucke, Klaus; Merck, Thomas; Müller, Sabine; Pawliczka, Iwona; Ronnenberg, Katrin; Rosenberger, Tanja; Ruser, Andreas; Tougaard, Jakob; Schuster, Max; Sundermeyer, Janne; Sveegaard, Signe; Siebert, Ursula

    2016-01-01

    The project conducts application-oriented research on impacts of underwater noise on marine vertebrates in the North and Baltic Seas. In distinct subprojects, the hearing sensitivity of harbor porpoises and gray seals as well as the acoustic tolerance limit of harbor porpoises to impulsive noise

  12. Sound Ecologies

    Directory of Open Access Journals (Sweden)

    Michelle Duffy

    2010-02-01

    Full Text Available Discussions about what constitutes ‘the rural’ invariably focus on notions of spatial location – of inhabiting spaces apart from that of the metropolitan. Deeply embedded in our images of what it means to be Australian, nonetheless our intellectual framing of ‘the rural’ as something outback and beyond has significant implications for our relations with these spaces. The relatively recent phenomenon of sea- and tree-changes has struck many unawares, and not simply because a good latté is so hard to find. Although a frivolous remark, such an apparent lack does shift our focus to a bodily scale of the rural; how is rural place re/made through our experiences of it? This article originates out of on-going research that explores the practice of listening and sound and the ways in which the body can draw attention to the intuitive, emotional, and psychoanalytical processes of subjectivity and place-making. Drawing on Nigel Thrift’s concept of an ecology of place, I suggest that contemporary heightened concerns with regards to loss and lack in rural Australia has led to a nascent emotional economy – one in which individual and intimate connections to the rural require a rethinking of how we live community and belonging. In such a terrain, what does it mean to be rural?

  13. Sound ecologies

    Directory of Open Access Journals (Sweden)

    Duffy, Michelle

    2010-01-01

    Full Text Available Discussions about what constitutes ‘the rural’ invariably focus on notions of spatial location – of inhabiting spaces apart from that of the metropolitan. Deeply embedded in our images of what it means to be Australian, nonetheless our intellectual framing of ‘the rural’ as something outback and beyond has significant implications for our relations with these spaces. The relatively recent phenomenon of sea- and tree-changes has struck many unawares, and not simply because a good latté is so hard to find. Although a frivolous remark, such an apparent lack does shift our focus to a bodily scale of the rural; how is rural place re/made through our experiences of it? This article originates out of on-going research that explores the practice of listening and sound and the ways in which the body can draw attention to the intuitive, emotional, and psychoanalytical processes of subjectivity and place-making. Drawing on Nigel Thrift’s concept of an ecology of place, I suggest that contemporary heightened concerns with regards to loss and lack in rural Australia has led to a nascent emotional economy – one in which individual and intimate connections to the rural require a rethinking of how we live community and belonging. In such a terrain, what does it mean to be rural?

  14. Coupled Modeling of Hydrodynamics and Sound in Coastal Ocean for Renewable Ocean Energy Development

    Energy Technology Data Exchange (ETDEWEB)

    Long, Wen; Jung, Ki Won; Yang, Zhaoqing; Copping, Andrea; Deng, Z. Daniel

    2016-03-01

    An underwater sound model was developed to simulate sound propagation from marine and hydrokinetic energy (MHK) devices or offshore wind (OSW) energy platforms. Finite difference methods were developed to solve the 3D Helmholtz equation for sound propagation in the coastal environment. A 3D sparse matrix solver with complex coefficients was formed for solving the resulting acoustic pressure field. The Complex Shifted Laplacian Preconditioner (CSLP) method was applied to solve the matrix system iteratively with MPI parallelization using a high performance cluster. The sound model was then coupled with the Finite Volume Community Ocean Model (FVCOM) for simulating sound propagation generated by human activities, such as construction of OSW turbines or tidal stream turbine operations, in a range-dependent setting. As a proof of concept, initial validation of the solver is presented for two coastal wedge problems. This sound model can be useful for evaluating impacts on marine mammals due to deployment of MHK devices and OSW energy platforms.

  15. Stability analysis of hybrid-driven underwater glider

    Science.gov (United States)

    Niu, Wen-dong; Wang, Shu-xin; Wang, Yan-hui; Song, Yang; Zhu, Ya-qiang

    2017-10-01

    Hybrid-driven underwater glider is a new type of unmanned underwater vehicle, which combines the advantages of autonomous underwater vehicles and traditional underwater gliders. The autonomous underwater vehicles have good maneuverability and can travel with a high speed, while the traditional underwater gliders are highlighted by low power consumption, long voyage, long endurance and good stealth characteristics. The hybrid-driven underwater gliders can realize variable motion profiles by their own buoyancy-driven and propeller propulsion systems. Stability of the mechanical system determines the performance of the system. In this paper, the Petrel-II hybrid-driven underwater glider developed by Tianjin University is selected as the research object and the stability of hybrid-driven underwater glider unitedly controlled by buoyancy and propeller has been targeted and evidenced. The dimensionless equations of the hybrid-driven underwater glider are obtained when the propeller is working. Then, the steady speed and steady glide path angle under steady-state motion have also been achieved. The steady-state operating conditions can be calculated when the hybrid-driven underwater glider reaches the desired steady-state motion. And the steadystate operating conditions are relatively conservative at the lower bound of the velocity range compared with the range of the velocity derived from the method of the composite Lyapunov function. By calculating the hydrodynamic coefficients of the Petrel-II hybrid-driven underwater glider, the simulation analysis has been conducted. In addition, the results of the field trials conducted in the South China Sea and the Danjiangkou Reservoir of China have been presented to illustrate the validity of the analysis and simulation, and to show the feasibility of the method of the composite Lyapunov function which verifies the stability of the Petrel-II hybrid-driven underwater glider.

  16. Underwater wireless optical communication using a blue-light leaky feeder

    Science.gov (United States)

    Xu, Jing; Sun, Bin; Kong, Meiwei; Lin, Aobo; Sarwar, Rohail; Han, Jun; Zhang, Wei; Deng, Ning

    2017-08-01

    A novel concept of using a leaky plastic optical fiber (POF) as the leaky feeder for underwater wireless optical communication (UWOC) is proposed and experimentally demonstrated. The leaky POF can potentially improve the UWOC coverage. Orthogonal frequency division multiplexing (OFDM) is employed in the demonstration to increase spectral efficiency and robustness to modal dispersion of the leaky POF with a large core. A bit rate of 224.61 Mb/s (net bit rate: 183.69 Mb/s) at the two discrete radiation points along a 10-m leaky POF feeder is achieved using 16-quadrature amplitude modulation (QAM)-OFDM modulation. Over a 30-cm underwater channel, the mean bit errors (BERs) measured at the two points are 3.37×10-5 and 3.35×10-3, respectively, which are below the FEC threshold of 3.8×10-3.

  17. Development and application of underwater robot vehicle for close inspection of spent fuels

    International Nuclear Information System (INIS)

    Yun, J. S.; Park, B. S.; Song, T. G.; Kim, S. H.; Cho, M. W.; Ahn, S. H.; Lee, J. Y.; Oh, S. C.; Oh, W. J.; Shin, K. W.; Woo, D. H.; Kim, H. G.; Park, J. S.

    1999-12-01

    The research and development efforts of the underwater robotic vehicle for inspection of spent fuels are focused on the development of an robotic vehicle which inspects spent fuels in the storage pool through remotely controlled actuation. For this purpose, a self balanced vehicle actuated by propellers is designed and fabricated, which consists of a radiation resistance camera, two illuminators, a pressure transducer and a manipulator. the algorithm for autonomous navigation is developed and its performance is tested at the swimming pool. The results of the underwater vehicle shows that the vehicle can easily navigate into the arbitrary directions while maintaining its balanced position. The camera provides a clear view of working environment by using the macro and zoom functions. The camera tilt device provides a wide field of view which is enough for monitoring the operation of manipulator. Also, the manipulator can pick up the dropped objects up to 4 kgf of weight. (author)

  18. An underwater robot controls water tanks in nuclear power plants

    International Nuclear Information System (INIS)

    Lardiere, C.

    2015-01-01

    The enterprises Newton Research Labs and IHI Southwest Technologies have developed a robot equipped with sensors to inspect the inside walls (partially) and bottom of water tanks without being obliged to empty them. The robot called 'Inspector' is made up of 4 main components: a chassis with 4 independent steering wheels, a camera video system able to provide a 360 degree view, various non-destructive testing devices such as underwater laser scanners, automated ultra-sound or Foucault current probes and an operation system for both driving the robot and controlling the testing. The Inspector robot has been used to inspect the inside bottom of an operating condensate tank at the Palo Verde nuclear station. The robot was able to check all the welds joining the bottom plates and the welds between the walls and the bottom. The robot is also able to come back to the exact place where a defect was detected during a previous inspection. (A.C.)

  19. Upper limb joint forces and moments during underwater cyclical movements.

    Science.gov (United States)

    Lauer, Jessy; Rouard, Annie Hélène; Vilas-Boas, João Paulo

    2016-10-03

    Sound inverse dynamics modeling is lacking in aquatic locomotion research because of the difficulty in measuring hydrodynamic forces in dynamic conditions. Here we report the successful implementation and validation of an innovative methodology crossing new computational fluid dynamics and inverse dynamics techniques to quantify upper limb joint forces and moments while moving in water. Upper limb kinematics of seven male swimmers sculling while ballasted with 4kg was recorded through underwater motion capture. Together with body scans, segment inertial properties, and hydrodynamic resistances computed from a unique dynamic mesh algorithm capable to handle large body deformations, these data were fed into an inverse dynamics model to solve for joint kinetics. Simulation validity was assessed by comparing the impulse produced by the arms, calculated by integrating vertical forces over a stroke period, to the net theoretical impulse of buoyancy and ballast forces. A resulting gap of 1.2±3.5% provided confidence in the results. Upper limb joint load was within 5% of swimmer׳s body weight, which tends to supports the use of low-load aquatic exercises to reduce joint stress. We expect this significant methodological improvement to pave the way towards deeper insights into the mechanics of aquatic movement and the establishment of practice guidelines in rehabilitation, fitness or swimming performance. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Urban Sound Ecologies

    DEFF Research Database (Denmark)

    Groth, Sanne Krogh; Samson, Kristine

    2013-01-01

    Within recent years, there has been a renewed focus on sound in urban environments. From sound installations in public space to sound festivals in alternative settings, we find a common interest in sound art relating to the urban environment. Artworks or interventions presented in such contexts s...

  1. Sound reproduction system

    NARCIS (Netherlands)

    Boone, M.M.; De Vries, D.; Horbach, U.

    2002-01-01

    Arrangement of a sound reproduction system (1), including at least one input (2), a sound field generator (4), a loudspeaker panel (10); the at least one input (2) connected to the sound filed generator (4), and the sound filed (4) connected to the loudspeaker panel (10); the at least one input (2)

  2. The Sound of Science

    Science.gov (United States)

    Merwade, Venkatesh; Eichinger, David; Harriger, Bradley; Doherty, Erin; Habben, Ryan

    2014-01-01

    While the science of sound can be taught by explaining the concept of sound waves and vibrations, the authors of this article focused their efforts on creating a more engaging way to teach the science of sound--through engineering design. In this article they share the experience of teaching sound to third graders through an engineering challenge…

  3. Ultrathin metasurface with high absorptance for waterborne sound

    KAUST Repository

    Mei, Jun

    2018-01-12

    We present a design for an acoustic metasurface which can efficiently absorb low-frequency sound energy in water. The metasurface has a simple structure and consists of only two common materials: i.e., water and silicone rubber. The optimized material and geometrical parameters of the designed metasurface are determined by an analytic formula in conjunction with an iterative process based on the retrieval method. Although the metasurface is as thin as 0.15 of the wavelength, it can absorb 99.7% of the normally incident sound wave energy. Furthermore, the metasurface maintains a substantially high absorptance over a relatively broad bandwidth, and also works well for oblique incidence with an incident angle of up to 50°. Potential applications in the field of underwater sound isolation are expected.

  4. Ultrathin metasurface with high absorptance for waterborne sound

    Science.gov (United States)

    Mei, Jun; Zhang, Xiujuan; Wu, Ying

    2018-03-01

    We present a design for an acoustic metasurface which can efficiently absorb low-frequency sound energy in water. The metasurface has a simple structure and consists of only two common materials: i.e., water and silicone rubber. The optimized material and geometrical parameters of the designed metasurface are determined by an analytic formula in conjunction with an iterative process based on the retrieval method. Although the metasurface is as thin as 0.15 of the wavelength, it can absorb 99.7% of the normally incident sound wave energy. Furthermore, the metasurface maintains a substantially high absorptance over a relatively broad bandwidth, and also works well for oblique incidence with an incident angle of up to 50°. Potential applications in the field of underwater sound isolation are expected.

  5. Underwater videography and photography in Gulf of Kachchh. Sponsored by Gujarat Ecological Society, Vadodara, Gujarat

    Digital Repository Service at National Institute of Oceanography (India)

    Marine Archaeology Centre (MAC) has been carrying out underwater explorations and excavations of ancient ports and sunken shipwrecks to preserve underwater cultural heritage. MAC has the infrastructure facility to carry out underwater investigations...

  6. Hydrodynamic Coefficients Identification and Experimental Investigation for an Underwater Vehicle

    Directory of Open Access Journals (Sweden)

    Shaorong XIE

    2014-02-01

    Full Text Available Hydrodynamic coefficients are the foundation of unmanned underwater vehicles modeling and controller design. In order to reduce identification complexity and acquire necessary hydrodynamic coefficients for controllers design, the motion of the unmanned underwater vehicle was separated into vertical motion and horizontal motion models. Hydrodynamic coefficients were regarded as mapping parameters from input forces and moments to output velocities and acceleration of the unmanned underwater vehicle. The motion models of the unmanned underwater vehicle were nonlinear and Genetic Algorithm was adopted to identify those hydrodynamic coefficients. To verify the identification quality, velocities and acceleration of the unmanned underwater vehicle was measured using inertial sensor under the same conditions as Genetic Algorithm identification. Curves similarity between measured velocities and acceleration and those identified by Genetic Algorithm were used as optimizing standard. It is found that the curves similarity were high and identified hydrodynamic coefficients of the unmanned underwater vehicle satisfied the measured motion states well.

  7. Delay Tolerance in Underwater Wireless Communications: A Routing Perspective

    Directory of Open Access Journals (Sweden)

    Safdar Hussain Bouk

    2016-01-01

    Full Text Available Similar to terrestrial networks, underwater wireless networks (UWNs also aid several critical tasks including coastal surveillance, underwater pollution detection, and other maritime applications. Currently, once underwater sensor nodes are deployed at different levels of the sea, it is nearly impossible or very expensive to reconfigure the hardware, for example, battery. Taking this issue into account, considerable amount of research has been carried out to ensure minimum energy costs and reliable communication between underwater nodes and base stations. As a result, several different network protocols were proposed for UWN, including MAC, PHY, transport, and routing. Recently, a new paradigm was introduced claiming that the intermittent nature of acoustic channel and signal resulted in designing delay tolerant routing schemes for the UWN, known as an underwater delay tolerant network. In this paper, we provide a comprehensive survey of underwater routing protocols with emphasis on the limitations, challenges, and future open issues in the context of delay tolerant network routing.

  8. Acoustic radiation force on a multilayered sphere in a Gaussian standing field

    Science.gov (United States)

    Wang, Haibin; Liu, Xiaozhou; Gao, Sha; Cui, Jun; Liu, Jiehui; He, Aijun; Zhang, Gutian

    2018-03-01

    We develop a model for calculating the radiation force on spherically symmetric multilayered particles based on the acoustic scattering approach. An expression is derived for the radiation force on a multilayered sphere centered on the axis of a Gaussian standing wave propagating in an ideal fluid. The effects of the sound absorption of the materials and sound wave on acoustic radiation force of a multilayered sphere immersed in water are analyzed, with particular emphasis on the shell thickness of every layer, and the width of the Gaussian beam. The results reveal that the existence of particle trapping behavior depends on the choice of the non-dimensional frequency ka, as well as the shell thickness of each layer. This study provides a theoretical basis for the development of acoustical tweezers in a Gaussian standing wave, which may benefit the improvement and development of acoustic control technology, such as trapping, sorting, and assembling a cell, and drug delivery applications. Project supported by National Key R&D Program (Grant No. 2016YFF0203000), the National Natural Science Foundation of China (Grant Nos. 11774167 and 61571222), the Fundamental Research Funds for the Central Universities of China (Grant No. 020414380001), the Key Laboratory of Underwater Acoustic Environment, Institute of Acoustics, Chinese Academy of Sciences (Grant No. SSHJ-KFKT-1701), and the AQSIQ Technology R&D Program of China (Grant No. 2017QK125).

  9. An Evaluation of Potential Operating Systems for Autonomous Underwater Vehicles

    Science.gov (United States)

    2013-02-01

    remote control of such vehicles requires the use of a tether , limiting the vehicle’s range; however operating underwater vehicles autonomously requires...URBI Universal Robot Body Interface UUV Unmanned Underwater Vehicle UNCLASSIFIED xi DSTO–TN–1194 UNCLASSIFIED THIS PAGE IS INTENTIONALLY BLANK xii... underwater environment, where many platforms are still reliant upon an umbilical tether for power and high bandwidth communications. This tether

  10. On the Performance of the Underwater Acoustic Sensor Networks

    Science.gov (United States)

    2015-05-01

    waves for Underwater Wireless Communication (UWC); radio waves, optical waves, and acoustic waves are few to name. Radio waves are good for extra low...2211 underwater communication , wireless sensors, mutual information REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR...Cotae, “On the Performance of the Underwater Wireless Communication Sensor Networks: Work in Progress” ASEE Mid-Atlantic Fall 2014 Conference

  11. Underwater noise modelling for environmental impact assessment

    Energy Technology Data Exchange (ETDEWEB)

    Farcas, Adrian [Centre for Environment, Fisheries and Aquaculture Science (Cefas), Pakefield Road, Lowestoft, NR33 0HT (United Kingdom); Thompson, Paul M. [Lighthouse Field Station, Institute of Biological and Environmental Sciences, University of Aberdeen, Cromarty IV11 8YL (United Kingdom); Merchant, Nathan D., E-mail: nathan.merchant@cefas.co.uk [Centre for Environment, Fisheries and Aquaculture Science (Cefas), Pakefield Road, Lowestoft, NR33 0HT (United Kingdom)

    2016-02-15

    Assessment of underwater noise is increasingly required by regulators of development projects in marine and freshwater habitats, and noise pollution can be a constraining factor in the consenting process. Noise levels arising from the proposed activity are modelled and the potential impact on species of interest within the affected area is then evaluated. Although there is considerable uncertainty in the relationship between noise levels and impacts on aquatic species, the science underlying noise modelling is well understood. Nevertheless, many environmental impact assessments (EIAs) do not reflect best practice, and stakeholders and decision makers in the EIA process are often unfamiliar with the concepts and terminology that are integral to interpreting noise exposure predictions. In this paper, we review the process of underwater noise modelling and explore the factors affecting predictions of noise exposure. Finally, we illustrate the consequences of errors and uncertainties in noise modelling, and discuss future research needs to reduce uncertainty in noise assessments.

  12. Ocean Research Enabled by Underwater Gliders

    Science.gov (United States)

    Rudnick, Daniel L.

    2016-01-01

    Underwater gliders are autonomous underwater vehicles that profile vertically by changing their buoyancy and use wings to move horizontally. Gliders are useful for sustained observation at relatively fine horizontal scales, especially to connect the coastal and open ocean. In this review, research topics are grouped by time and length scales. Large-scale topics addressed include the eastern and western boundary currents and the regional effects of climate variability. The accessibility of horizontal length scales of order 1 km allows investigation of mesoscale and submesoscale features such as fronts and eddies. Because the submesoscales dominate vertical fluxes in the ocean, gliders have found application in studies of biogeochemical processes. At the finest scales, gliders have been used to measure internal waves and turbulent dissipation. The review summarizes gliders' achievements to date and assesses their future in ocean observation.

  13. Little Sounds

    Directory of Open Access Journals (Sweden)

    Baker M. Bani-Khair

    2017-10-01

    Full Text Available The Spider and the Fly   You little spider, To death you aspire... Or seeking a web wider, To death all walking, No escape you all fighters… Weak and fragile in shape and might, Whatever you see in the horizon, That is destiny whatever sight. And tomorrow the spring comes, And the flowers bloom, And the grasshopper leaps high, And the frogs happily cry, And the flies smile nearby, To that end, The spider has a plot, To catch the flies by his net, A mosquito has fallen down in his net, Begging him to set her free, Out of that prison, To her freedom she aspires, Begging...Imploring...crying,  That is all what she requires, But the spider vows never let her free, His power he admires, Turning blind to light, And with his teeth he shall bite, Leaving her in desperate might, Unable to move from site to site, Tied up with strings in white, Wrapped up like a dead man, Waiting for his grave at night,   The mosquito says, Oh little spider, A stronger you are than me in power, But listen to my words before death hour, Today is mine and tomorrow is yours, No escape from death... Whatever the color of your flower…     Little sounds The Ant The ant is a little creature with a ferocious soul, Looking and looking for more and more, You can simply crush it like dead mold, Or you can simply leave it alone, I wonder how strong and strong they are! Working day and night in a small hole, Their motto is work or whatever you call… A big boon they have and joy in fall, Because they found what they store, A lesson to learn and memorize all in all, Work is something that you should not ignore!   The butterfly: I’m the butterfly Beautiful like a blue clear sky, Or sometimes look like snow, Different in colors, shapes and might, But something to know that we always die, So fragile, weak and thin, Lighter than a glimpse and delicate as light, Something to know for sure… Whatever you have in life and all these fields, You are not happier than a butterfly

  14. A MAC protocol for underwater sensors networks

    OpenAIRE

    Santos, Rodrigo; Orozco, Javier; Ochoa, Sergio; Meseguer Pallarès, Roc; Eggly, Gabriel

    2015-01-01

    “The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-26401-1_37." Underwater sensor networks are becoming an important field of research, because of its everyday increasing application scope. Examples of their application areas are environmental and pollution monitoring (mainly oil spills), oceanographic data collection, support for submarine geo-localization, ocean sampling and early tsunamis alert. It is well-known the challenge that represents to perfo...

  15. Passive Mode Carbon Nanotube Underwater Acoustic Transducer

    Science.gov (United States)

    2016-09-20

    irreversible Joule heat) by an electric light bulb . The reciprocal (or reverse) of this process by supplying heat and shining light to the same electric bulb ...limit the invention to the precise form disclosed; and obviously many modifications and variations are possible in light of the above teaching...300151 1 of 14 PASSIVE MODE CARBON NANOTUBE UNDERWATER ACOUSTIC TRANSDUCER STATEMENT OF GOVERNMENT INTEREST [0001] The invention described

  16. Underwater suction device for irradiated materials

    International Nuclear Information System (INIS)

    Qurnell, F.D.; Peloquin, A.V.

    1982-01-01

    An underwater suction device for collecting irradiated materials in a pool of water includes injection and suction tubes and a removable, disposable filter for capturing irradiated materials. Pressurized water is injected into the suction tube through a jet pump nozzle to establish a suction flow through the tube. The suction device is manoeuverable by a pole, which is pivotally connected to the suction device by a latching mechanism. (author)

  17. Tethered Antennas for Unmanned Underwater Vehicles

    Science.gov (United States)

    2009-04-27

    Concepts The first design (Figure 1) was based on the concept of an airfoil kite. The shape of the tow body was built around a NACA5515 hydrofoil to...Underwater Vehicles Brooke Ocean Technology (USA) Inc. 6 Figure 1: Hydrofoil Design The second design was based on that of a boat hull...communications. A sharp bow was utilized to cut through the water to reduce drag when on the surface. Like the hydrofoil design the top profile was

  18. MEDITERRANEAN: Underwater neutrinos get off the ground

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    Now funded is the initial stage of NESTOR, an imaginative new programme for a dedicated underwater neutrino astroparticle physics laboratory. Located in the international waters off the southernmost corner of continental Europe near the town of Pylos in S.W. Greece, NESTOR (NEutrinos from Supernovae and TeV sources Ocean Range) recalls the wise king of Pylos who counselled the Greeks during the Trojan war, an excellent tradition for new scientific goals of detecting neutrinos

  19. Role of Confined Water in Underwater Adhesion

    Science.gov (United States)

    Dhinojwala, Ali

    Surface bound water is a strong deterrent for forming strong bonds between two surfaces underwater and expelling that bound water is important for strong adhesion. I will discuss examples of different strategies used by geckos, spiders, and mussels to handle this last layer of bound water. Recent results using infrared-visible sum frequency generation spectroscopy to probe the structure of this bound water will be discussed. National Science Foundation.

  20. Obstacle avoidance in underwater glider path planning

    OpenAIRE

    Isern González, Josep; Hernández Sosa, Daniel; Fernández Perdomo, Enrique; Cabrera Gámez, Jorge; Domínguez Brito, Antonio Carlos; Prieto Marañón, Víctor

    2012-01-01

    Underwater gliders have revealed as a valuable scientific platform, with a growing number of successful environmental sampling applications. They are specially suited for long range missions due to their unmatched autonomy level, although their low surge speed make them strongly affected by ocean currents. Path planning constitute a real concern for this type of vehicle, as it may reduce the time taken to reach a given waypoint or save power. In such a dynamic environment it is not easy to fi...

  1. A Recovery System for Unmanned Underwater Vehicles

    Science.gov (United States)

    2017-09-28

    300170 1 of 10 A RECOVERY SYSTEM FOR UNMANNED UNDERWATER VEHICLES STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may...6 of 10 forces cannot be easily predicted and can be strong enough to require a significantly larger handling system and significantly more...the sea state, the ship handling system , the capture mechanism and the design of the capture mechanism 400. [0024] The water jets 100 will increase

  2. Reef Sound as an Orientation Cue for Shoreward Migration by Pueruli of the Rock Lobster, Jasus edwardsii.

    Science.gov (United States)

    Hinojosa, Ivan A; Green, Bridget S; Gardner, Caleb; Hesse, Jan; Stanley, Jenni A; Jeffs, Andrew G

    2016-01-01

    The post-larval or puerulus stage of spiny, or rock, lobsters (Palinuridae) swim many kilometres from open oceans into coastal waters where they subsequently settle. The orientation cues used by the puerulus for this migration are unclear, but are presumed to be critical to finding a place to settle. Understanding this process may help explain the biological processes of dispersal and settlement, and be useful for developing realistic dispersal models. In this study, we examined the use of reef sound as an orientation cue by the puerulus stage of the southern rock lobster, Jasus edwardsii. Experiments were conducted using in situ binary choice chambers together with replayed recording of underwater reef sound. The experiment was conducted in a sandy lagoon under varying wind conditions. A significant proportion of puerulus (69%) swam towards the reef sound in calm wind conditions. However, in windy conditions (>25 m s-1) the orientation behaviour appeared to be less consistent with the inclusion of these results, reducing the overall proportion of pueruli that swam towards the reef sound (59.3%). These results resolve previous speculation that underwater reef sound is used as an orientation cue in the shoreward migration of the puerulus of spiny lobsters, and suggest that sea surface winds may moderate the ability of migrating pueruli to use this cue to locate coastal reef habitat to settle. Underwater sound may increase the chance of successful settlement and survival of this valuable species.

  3. Research on Operational Aspects of Large Autonomous Underwater Glider Fleets

    National Research Council Canada - National Science Library

    Fratantoni, David M

    2007-01-01

    This program supported research on the operational and management issues stemming from application of large fleets of autonomous underwater gliders to oceanographic research and rapid environmental...

  4. Underwater hearing in the great cormorant (Phalacrocorax carbo sinensis)

    DEFF Research Database (Denmark)

    Hansen, Kirstin Anderson; Larsen, Ole Næsbye; Wahlberg, Magnus

    2016-01-01

    The underwater hearing threshold of a great cormorant (Phalacrocroax carbo sinensis) was measured at 2 kHz using psychophysical methods. Previous in-air and underwater testing suggests that cormorants have rather poor in-air hearing compared to other birds of similar size (Johansen, 2016). Prelim......The underwater hearing threshold of a great cormorant (Phalacrocroax carbo sinensis) was measured at 2 kHz using psychophysical methods. Previous in-air and underwater testing suggests that cormorants have rather poor in-air hearing compared to other birds of similar size (Johansen, 2016...

  5. Calibration Techniques for Accurate Measurements by Underwater Camera Systems.

    Science.gov (United States)

    Shortis, Mark

    2015-12-07

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems.

  6. Calibration Techniques for Accurate Measurements by Underwater Camera Systems

    Directory of Open Access Journals (Sweden)

    Mark Shortis

    2015-12-01

    Full Text Available Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems.

  7. Automatic stabilization of underwater robots in the time manipulation operations

    International Nuclear Information System (INIS)

    Filaretov, V.F.; Koval, E.V.

    1994-01-01

    When carrying out underwater technical works by means of an underwater vehicles having a manipulator it is desirable to perform manipulation operations in the regime of the underwater vehicle hovering above the object without durable and complicated operations up its rigid fixation. Underwater vehicle stabilization is achieved by compensation all the effects on the vehicle caused by the operating manipulator in water medium. This automatic stabilization is formed due to input of the required control signals into corresponding vehicle propellers proportional to calculated components of the generalized forces and moments. The propellers should form stops reacting against effects

  8. Contour Tracking Control for the REMUS Autonomous Underwater Vehicle

    National Research Council Canada - National Science Library

    Van Reet, Alan R

    2005-01-01

    In the interest of enhancing the capabilities of autonomous underwater vehicles used in US Naval Operations, controlling vehicle position to follow depth contours presents exciting potential for navigation...

  9. Autopilot Using Differential Thrust for ARIES Autonomous Underwater Vehicle

    National Research Council Canada - National Science Library

    Sarton, Christopher

    2003-01-01

    .... Unfortunately, communication antennas must point to specific satellites in this system and thus underwater vehicles must steer a specific course on the surface during the communication process...

  10. Do top predators cue on sound production by mesopelagic prey?

    Science.gov (United States)

    Baumann-Pickering, S.; Checkley, D. M., Jr.; Demer, D. A.

    2016-02-01

    Deep-scattering layer (DSL) organisms, comprising a variety of mesopelagic fishes, and squids, siphonophores, crustaceans, and other invertebrates, are preferred prey for numerous large marine predators, e.g. cetaceans, seabirds, and fishes. Some of the DSL species migrate from depth during daylight to feed near the surface at night, transitioning during dusk and dawn. We investigated if any DSL organisms create sound, particularly during the crepuscular periods. Over several nights in summer 2015, underwater sound was recorded in the San Diego Trough using a high-frequency acoustic recording package (HARP, 10 Hz to 100 kHz), suspended from a drifting surface float. Acoustic backscatter from the DSL was monitored nearby using a calibrated multiple-frequency (38, 70, 120, and 200 kHz) split-beam echosounder (Simrad EK60) on a small boat. DSL organisms produced sound, between 300 and 1000 Hz, and the received levels were highest when the animals migrated past the recorder during ascent and descent. The DSL are globally present, so the observed acoustic phenomenon, if also ubiquitous, has wide-reaching implications. Sound travels farther than light or chemicals and thus can be sensed at greater distances by predators, prey, and mates. If sound is a characteristic feature of pelagic ecosystems, it likely plays a role in predator-prey relationships and overall ecosystem dynamics. Our new finding inspires numerous questions such as: Which, how, and why have DSL organisms evolved to create sound, for what do they use it and under what circumstances? Is sound production by DSL organisms truly ubiquitous, or does it depend on the local environment and species composition? How may sound production and perception be adapted to a changing environment? Do predators react to changes in sound? Can sound be used to quantify the composition of mixed-species assemblages, component densities and abundances, and hence be used in stock assessment or predictive modeling?

  11. Underwater Acoustic Target Tracking: A Review.

    Science.gov (United States)

    Luo, Junhai; Han, Ying; Fan, Liying

    2018-01-02

    Advances in acoustic technology and instrumentation now make it possible to explore marine resources. As a significant component of ocean exploration, underwater acoustic target tracking has aroused wide attention both in military and civil fields. Due to the complexity of the marine environment, numerous techniques have been proposed to obtain better tracking performance. In this paper, we survey over 100 papers ranging from innovative papers to the state-of-the-art in this field to present underwater tracking technologies. Not only the related knowledge of acoustic tracking instrument and tracking progress is clarified in detail, but also a novel taxonomy method is proposed. In this paper, algorithms for underwater acoustic target tracking are classified based on the methods used as: (1) instrument-assisted methods; (2) mode-based methods; (3) tracking optimization methods. These algorithms are compared and analyzed in the aspect of dimensions, numbers, and maneuvering of the tracking target, which is different from other survey papers. Meanwhile, challenges, countermeasures, and lessons learned are illustrated in this paper.

  12. Modeling and Control of Underwater Robotic Systems

    Energy Technology Data Exchange (ETDEWEB)

    Schjoelberg, I:

    1996-12-31

    This doctoral thesis describes modeling and control of underwater vehicle-manipulator systems. The thesis also presents a model and a control scheme for a system consisting of a surface vessel connected to an underwater robotic system by means of a slender marine structure. The equations of motion of the underwater vehicle and manipulator are described and the system kinematics and properties presented. Feedback linearization technique is applied to the system and evaluated through a simulation study. Passivity-based controllers for vehicle and manipulator control are presented. Stability of the closed loop system is proved and simulation results are given. The equation of motion for lateral motion of a cable/riser system connected to a surface vessel at the top end and to a thruster at the bottom end is described and stability analysis and simulations are presented. The equations of motion in 3 degrees of freedom of the cable/riser, surface vessel and robotic system are given. Stability analysis of the total system with PD-controllers is presented. 47 refs., 32 figs., 7 tabs.

  13. Handling manipulator device in nuclear reactor and radiation-degradation analysis method

    International Nuclear Information System (INIS)

    Mizumachi, Yuichiro; Aoki, Masataka.

    1996-01-01

    The present invention concerns a radiation-degradation analyzing method in which remaining life of an underwater device main body is forecast by using a robot device operated in a nuclear reactor based on radiation dose. The underwater device main body comprising a TV camera for visual inspection for the reactor and a propulsion device is controlled by way of cables. Information for depth obtained from a depth gauge and dose rate distribution in the reactor are read successively into a memory of a computer in a calculation device for processing signals sent from the underwater device main body. Values of forecast radiation dose given to the underwater device main body till it is recovered is calculated, and forecast dose rate values are further added thereto forecast dose rate thereby forecasting remaining lifetime of parts relevant to the underwater device main body during operation. (N.H.)

  14. Sound spectrum of a pulsating optical discharge

    Energy Technology Data Exchange (ETDEWEB)

    Grachev, G N; Smirnov, A L; Tishchenko, V N [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Dmitriev, A K; Miroshnichenko, I B [Novosibirsk State Technical University (Russian Federation)

    2016-02-28

    A spectrum of sound of an optical discharge generated by a repetitively pulsed (RP) laser radiation has been investigated. The parameters of laser radiation are determined at which the spectrum of sound may contains either many lines, or the main line at the pulse repetition rate and several weaker overtones, or a single line. The spectrum of sound produced by trains of RP radiation comprises the line (and overtones) at the repetition rate of train sequences and the line at the repetition rate of pulses in trains. A CO{sub 2} laser with the pulse repetition rate of f ≈ 3 – 180 kHz and the average power of up to 2 W was used in the experiments. (optical discharges)

  15. Sound transmission reduction with intelligent panel systems

    Science.gov (United States)

    Fuller, Chris R.; Clark, Robert L.

    1992-01-01

    Experimental and theoretical investigations are performed of the use of intelligent panel systems to control the sound transmission and radiation. An intelligent structure is defined as a structural system with integrated actuators and sensors under the guidance of an adaptive, learning type controller. The system configuration is based on the Active Structural Acoustic Control (ASAC) concept where control inputs are applied directly to the structure to minimize an error quantity related to the radiated sound field. In this case multiple piezoelectric elements are employed as sensors. The importance of optimal shape and location is demonstrated to be of the same order of influence as increasing the number of channels of control.

  16. Synthesized size-sound sound symbolism

    NARCIS (Netherlands)

    Lockwood, G.F.; Hagoort, P.; Dingemanse, M.; Papafragou, A.; Grodner, D.; Mirman, D.; Trueswell, J.

    2016-01-01

    Studies of sound symbolism have shown that people can associate sound and meaning in consistent ways when presented with maximally contrastive stimulus pairs of nonwords such as bouba/kiki (rounded/sharp) or mil/mal (small/big). Recent work has shown the effect extends to antonymic words from

  17. Near-field and high-resolution cylindrical noise source location method based on vector sound pressure array

    Directory of Open Access Journals (Sweden)

    ZUO Xiang

    2017-08-01

    Full Text Available The existing underwater noise source near-field location method usually assumes that the measurement plane is flat, which increases the difficulty of applying the underwater noise target test for cylindrical distribution. Simultaneously, the conventional near-field focused beam has a lower spatial resolution when used to locate an underwater noise source with cylindrical distribution. Moreover, the near-field underwater noise source location method based on the sound pressure array has a left and right side fuzzy problem. In order to solve these problems, by establishing the near-field measurement model of the noise source with cylindrical distribution as the measurement surface, and combining the unilateral directivity of the vector hydrophone and the high resolution characteristics of the MUSIC algorithm, a near-field and high resolution location method is proposed for cylindrical distribution based on vector sound pressure, and a computer simulation is carried out. The results show that the method can use a smaller array aperture to locate the underwater noise source, enabling it to be used to locate and recognize the noise sources of complex and large-scale cylindrical systems.

  18. Making fictions sound real

    DEFF Research Database (Denmark)

    Langkjær, Birger

    2010-01-01

    of sounds. Apart from an account of the kinds of sounds that typically appear in a specific genre, a genre analysis of sound may also benefit from a functionalist approach that focuses on how sounds can make both realist and non-realist aspects of genres sound real to audiences.......This article examines the role that sound plays in making fictions perceptually real to film audiences, whether these fictions are realist or non-realist in content and narrative form. I will argue that some aspects of film sound practices and the kind of experiences they trigger are related...... to basic rules of human perception, whereas others are more properly explained in relation to how aesthetic devices, including sound, are used to characterise the fiction and thereby make it perceptually real to its audience. Finally, I will argue that not all genres can be defined by a simple taxonomy...

  19. Making fictions sound real

    DEFF Research Database (Denmark)

    Langkjær, Birger

    2010-01-01

    This article examines the role that sound plays in making fictions perceptually real to film audiences, whether these fictions are realist or non-realist in content and narrative form. I will argue that some aspects of film sound practices and the kind of experiences they trigger are related...... to basic rules of human perception, whereas others are more properly explained in relation to how aesthetic devices, including sound, are used to characterise the fiction and thereby make it perceptually real to its audience. Finally, I will argue that not all genres can be defined by a simple taxonomy...... of sounds. Apart from an account of the kinds of sounds that typically appear in a specific genre, a genre analysis of sound may also benefit from a functionalist approach that focuses on how sounds can make both realist and non-realist aspects of genres sound real to audiences....

  20. Sound wave transmission (image)

    Science.gov (United States)

    When sounds waves reach the ear, they are translated into nerve impulses. These impulses then travel to the brain where they are interpreted by the brain as sound. The hearing mechanisms within the inner ear, can ...

  1. Development of underwater laser cutting technique for steel and ...

    Indian Academy of Sciences (India)

    We have developed underwater cutting technique for 4.2 mm thick zircaloy pressure tubes and up to 6 mm thick steel using fibre-coupled 250 W average power pulsed Nd:YAG laser. This underwater cutting technique will be highly useful in various nuclear applications as well as in dismantling/repair of ship and pipe lines ...

  2. Visual-adaptation-mechanism based underwater object extraction

    Science.gov (United States)

    Chen, Zhe; Wang, Huibin; Xu, Lizhong; Shen, Jie

    2014-03-01

    Due to the major obstacles originating from the strong light absorption and scattering in a dynamic underwater environment, underwater optical information acquisition and processing suffer from effects such as limited range, non-uniform lighting, low contrast, and diminished colors, causing it to become the bottleneck for marine scientific research and projects. After studying and generalizing the underwater biological visual mechanism, we explore its advantages in light adaption which helps animals to precisely sense the underwater scene and recognize their prey or enemies. Then, aiming to transform the significant advantage of the visual adaptation mechanism into underwater computer vision tasks, a novel knowledge-based information weighting fusion model is established for underwater object extraction. With this bionic model, the dynamical adaptability is given to the underwater object extraction task, making them more robust to the variability of the optical properties in different environments. The capability of the proposed method to adapt to the underwater optical environments is shown, and its outperformance for the object extraction is demonstrated by comparison experiments.

  3. Self-localization for underwater inspection robot in reactor systems

    International Nuclear Information System (INIS)

    Kobayashi, Futoshi; Kojima, Fumio

    2007-01-01

    An underwater inspection robot has been needed for preventive maintenance in a nuclear power plant. This paper deals with a self-localization method for the underwater inspection robot. In this method, the position and the orientation of the robot are estimated by using the particle filter. For showing the effectiveness of the proposed method, an experiment with real robot is demonstrated. (author)

  4. Development of underwater laser cutting technique for steel and ...

    Indian Academy of Sciences (India)

    Laser cutting; underwater laser cutting; fibre optic beam delivery; Nd:YAG laser; material processing; heat affected zone; microstructure. PACS Nos 42.62.Cf; 42.62.-b; 42.55.Rz; 42.81.Ai; 42.81.-i. 1. Introduction. Underwater laser cutting and welding has many applications in nuclear facilities and shiping industry and is a ...

  5. Fish protection at water intakes using a new signal development process and sound system

    International Nuclear Information System (INIS)

    Loeffelman, P.H.; Klinect, D.A.; Van Hassel, J.H.

    1991-01-01

    American Electric Power Company, Inc., is exploring the feasibility of using a patented signal development process and sound system to guide aquatic animals with underwater sound. Sounds from animals such as chinook salmon, steelhead trout, striped bass, freshwater drum, largemouth bass, and gizzard shad can be used to synthesize a new signal to stimulate the animal in the most sensitive portion of its hearing range. AEP's field tests during its research demonstrate that adult chinook salmon, steelhead trout and warmwater fish, and steelhead trout and chinook salmon smolts can be repelled with a properly-tuned system. The signal development process and sound system is designed to be transportable and use animals at the site to incorporate site-specific factors known to affect underwater sound, e.g., bottom shape and type, water current, and temperature. This paper reports that, because the overall goal of this research was to determine the feasibility of using sound to divert fish, it was essential that the approach use a signal development process which could be customized to animals and site conditions at any hydropower plant site

  6. Broadcast sound technology

    CERN Document Server

    Talbot-Smith, Michael

    1990-01-01

    Broadcast Sound Technology provides an explanation of the underlying principles of modern audio technology. Organized into 21 chapters, the book first describes the basic sound; behavior of sound waves; aspects of hearing, harming, and charming the ear; room acoustics; reverberation; microphones; phantom power; loudspeakers; basic stereo; and monitoring of audio signal. Subsequent chapters explore the processing of audio signal, sockets, sound desks, and digital audio. Analogue and digital tape recording and reproduction, as well as noise reduction, are also explained.

  7. An Antropologist of Sound

    DEFF Research Database (Denmark)

    Groth, Sanne Krogh

    2015-01-01

    PROFESSOR PORTRAIT: Sanne Krogh Groth met Holger Schulze, newly appointed professor in Musicology at the Department for Arts and Cultural Studies, University of Copenhagen, to a talk about anthropology of sound, sound studies, musical canons and ideology.......PROFESSOR PORTRAIT: Sanne Krogh Groth met Holger Schulze, newly appointed professor in Musicology at the Department for Arts and Cultural Studies, University of Copenhagen, to a talk about anthropology of sound, sound studies, musical canons and ideology....

  8. Form Follows Sound

    OpenAIRE

    Caramiaux, Baptiste; Altavilla, Alessandro; Pobiner, Scott G.; Tanaka, Atau

    2015-01-01

    Sonic interaction is the continuous relationship between user actions and sound, mediated by some technology. Because interaction with sound may be task oriented or experience-based it is important to understand the nature of action-sound relationships in order to design rich sonic interactions. We propose a participatory approach to sonic interaction design that first considers the affordances of sounds in order to imagine embodied interaction, and based on this, generates interaction models...

  9. Modelling Hyperboloid Sound Scattering

    DEFF Research Database (Denmark)

    Burry, Jane; Davis, Daniel; Peters, Brady

    2011-01-01

    The Responsive Acoustic Surfaces workshop project described here sought new understandings about the interaction between geometry and sound in the arena of sound scattering. This paper reports on the challenges associated with modelling, simulating, fabricating and measuring this phenomenon using...... both physical and digital models at three distinct scales. The results suggest hyperboloid geometry, while difficult to fabricate, facilitates sound scattering....

  10. Abnormal sound detection device

    International Nuclear Information System (INIS)

    Yamada, Izumi; Matsui, Yuji.

    1995-01-01

    Only components synchronized with rotation of pumps are sampled from detected acoustic sounds, to judge the presence or absence of abnormality based on the magnitude of the synchronized components. A synchronized component sampling means can remove resonance sounds and other acoustic sounds generated at a synchronously with the rotation based on the knowledge that generated acoustic components in a normal state are a sort of resonance sounds and are not precisely synchronized with the number of rotation. On the other hand, abnormal sounds of a rotating body are often caused by compulsory force accompanying the rotation as a generation source, and the abnormal sounds can be detected by extracting only the rotation-synchronized components. Since components of normal acoustic sounds generated at present are discriminated from the detected sounds, reduction of the abnormal sounds due to a signal processing can be avoided and, as a result, abnormal sound detection sensitivity can be improved. Further, since it is adapted to discriminate the occurrence of the abnormal sound from the actually detected sounds, the other frequency components which are forecast but not generated actually are not removed, so that it is further effective for the improvement of detection sensitivity. (N.H.)

  11. Capacitive Micromachined Ultrasonic Transducers (CMUTs for Underwater Imaging Applications

    Directory of Open Access Journals (Sweden)

    Jinlong Song

    2015-09-01

    Full Text Available A capacitive micromachined ultrasonic transducer structure for use in underwater imaging is designed, fabricated and tested in this paper. In this structure, a silicon dioxide insulation layer is inserted between the top electrodes and the vibration membrane to prevent ohmic contact. The capacitance-voltage (C-V characteristic curve shows that the transducer offers suitable levels of hysteresis and repeatability performance. The −6 dB center frequency is 540 kHz and the transducer has a bandwidth of 840 kHz for a relative bandwidth of 155%. Underwater pressure of 143.43 Pa is achieved 1 m away from the capacitive micromachined ultrasonic transducer under 20  excitation. Two-dimensional underwater ultrasonic imaging, which is able to prove that a rectangular object is present underwater, is achieved. The results presented here indicate that our work will be highly beneficial for the establishment of an underwater ultrasonic imaging system.

  12. Underwater Sensor Network Redeployment Algorithm Based on Wolf Search.

    Science.gov (United States)

    Jiang, Peng; Feng, Yang; Wu, Feng

    2016-10-21

    This study addresses the optimization of node redeployment coverage in underwater wireless sensor networks. Given that nodes could easily become invalid under a poor environment and the large scale of underwater wireless sensor networks, an underwater sensor network redeployment algorithm was developed based on wolf search. This study is to apply the wolf search algorithm combined with crowded degree control in the deployment of underwater wireless sensor networks. The proposed algorithm uses nodes to ensure coverage of the events, and it avoids the prematurity of the nodes. The algorithm has good coverage effects. In addition, considering that obstacles exist in the underwater environment, nodes are prevented from being invalid by imitating the mechanism of avoiding predators. Thus, the energy consumption of the network is reduced. Comparative analysis shows that the algorithm is simple and effective in wireless sensor network deployment. Compared with the optimized artificial fish swarm algorithm, the proposed algorithm exhibits advantages in network coverage, energy conservation, and obstacle avoidance.

  13. A man-made object detection for underwater TV

    Science.gov (United States)

    Cheng, Binbin; Wang, Wenwu; Chen, Yao

    2018-03-01

    It is a great challenging task to complete an automatic search of objects underwater. Usually the forward looking sonar is used to find the target, and then the initial identification of the target is completed by the side-scan sonar, and finally the confirmation of the target is accomplished by underwater TV. This paper presents an efficient method for automatic extraction of man-made sensitive targets in underwater TV. Firstly, the image of underwater TV is simplified with taking full advantage of the prior knowledge of the target and the background; then template matching technology is used for target detection; finally the target is confirmed by extracting parallel lines on the target contour. The algorithm is formulated for real-time execution on limited-memory commercial-of-the-shelf platforms and is capable of detection objects in underwater TV.

  14. Sound reduction by metamaterial-based acoustic enclosure

    Directory of Open Access Journals (Sweden)

    Shanshan Yao

    2014-12-01

    Full Text Available In many practical systems, acoustic radiation control on noise sources contained within a finite volume by an acoustic enclosure is of great importance, but difficult to be accomplished at low frequencies due to the enhanced acoustic-structure interaction. In this work, we propose to use acoustic metamaterials as the enclosure to efficiently reduce sound radiation at their negative-mass frequencies. Based on a circularly-shaped metamaterial model, sound radiation properties by either central or eccentric sources are analyzed by numerical simulations for structured metamaterials. The parametric analyses demonstrate that the barrier thickness, the cavity size, the source type, and the eccentricity of the source have a profound effect on the sound reduction. It is found that increasing the thickness of the metamaterial barrier is an efficient approach to achieve large sound reduction over the negative-mass frequencies. These results are helpful in designing highly efficient acoustic enclosures for blockage of sound in low frequencies.

  15. Autonomous underwater handling system for service, measurement and cutting tasks for the decommissioning of nuclear facilities

    International Nuclear Information System (INIS)

    Hahn, M.; Haferkamp, H.; Bach, W.; Rose, N.

    1992-01-01

    For about 10 years the Institute for Material Science at the Hanover University has worked on projects of underwater cutting and welding. Increasing tasks to be done in nuclear facilities led to the development of special handling systems to support and handle the cutting tools. Also sensors and computers for extensive and complex tasks were integrated. A small sized freediving handling system, equipped with 2 video cameras, ultrasonic and radiation sensors and a plasma cutting torch for inspection and decommissioning tasks in nuclear facilities is described in this paper. (Author)

  16. Underwater welding using remote controlled robots. Development of remote underwater welding technology with a high power YAG laser

    International Nuclear Information System (INIS)

    Miwa, Yasuhiro; Sato, Syuuichi; Kojima, Toshio; Owaki, Katsura; Hirose, Naoya

    2002-01-01

    As components in nuclear power plant have been periodically carried out their inspection and repair to keep their integrity, on radioactive liquid wastes storage facility, because of difficulty on their inspection by human beings, some are remained without inspection, and even when capable of inspection, conversion from human works to remote operations is desired from a viewpoint of their operation efficiency upgrading. For response to these needs, some developments on a technology capable of carrying out inspection of their inside at underwater environment and repairing welding with YAG laser by means of remote operation, have been performed. Remote underwater inspection and repair technology is a combination technology of already applied underwater mobile technique (underwater inspection robot) with underwater YAG laser welding technique which is recently at actual using level. Therefore, this technology is composed of an inspection robot and a repair welding robot. And, testing results using the underwater inspection robot and welding test results using the underwater repair welding robot, were enough preferable to obtain forecasting applicable to actual apparatuses. This technology is especially effective for inspection and repair of inside of nuclear fuel cycle apparatuses and relatively high dose apparatuses, and can be thought to be applicable also to large capacity tanks, tanks dealing with harmful matters, underwater structures, and so on, in general industries. (G.K.)

  17. Water waves generated by underwater explosion

    CERN Document Server

    Mehaute, Bernard Le

    1996-01-01

    This is the first book on explosion-generated water waves. It presents the theoretical foundations and experimental results of the generation and propagation of impulsively generated waves resulting from underwater explosions. Many of the theories and concepts presented herein are applicable to other types of water waves, in particular, tsunamis and waves generated by the fall of a meteorite. Linear and nonlinear theories, as well as experimental calibrations, are presented for cases of deep and shallow water explosions. Propagation of transient waves on dissipative, nonuniform bathymetries to

  18. Radon dynamics in underwater thermal radon therapy

    International Nuclear Information System (INIS)

    Lettner, H.; Hofmann, W.; Winkler, R.; Rolle, R.; Foisner, W.

    1998-01-01

    At a facility for underwater thermal radon therapy in Bad Hofgastein, experiments were carried out with the aim of establishing radon in the air exhaled by the treated patients and of radon decay products on the skin of the patients. The time course of radon concentration in the exhaled air shows a maximum a few minutes after entering the bath, then the Rn concentration remains constant over the remaining time spent in the bath. Taking into account several simplifying assumptions, the average dose to the epidermis from radon daughters is about 50 μGy. (A.K.)

  19. Navigation System Fault Diagnosis for Underwater Vehicle

    DEFF Research Database (Denmark)

    Falkenberg, Thomas; Gregersen, Rene Tavs; Blanke, Mogens

    2014-01-01

    This paper demonstrates fault diagnosis on unmanned underwater vehicles (UUV) based on analysis of structure of the nonlinear dynamics. Residuals are generated using dierent approaches in structural analysis followed by statistical change detection. Hypothesis testing thresholds are made signal...... based to cope with non-ideal properties seen in real data. Detection of both sensor and thruster failures are demonstrated. Isolation is performed using the residual signature of detected faults and the change detection algorithm is used to assess severity of faults by estimating their magnitude...

  20. Adaptive Target Tracking for Underwater Maneuvering Targets.

    Science.gov (United States)

    1979-12-01

    concenetrate on the bearings-only approach. In this method the Observer monitors his bearing to the Source, over a period of time. Usually the Observer must...developed in [ 5] was earlier applied with much success to tracking maneuvering air targets. This approach will now be applied in the underwater environment...April 1977. [11] A. H. Jazwinski, Stochastic Processes and Filtering Theory, Academic Press, New York, 1970. [12] D. H. Halliday, and R. Resnick, Physics, John Wiley & Sons, Inc., New York, 1966. hI

  1. 46 CFR 115.650 - Alternative Hull Examination (AHE) Program options: Divers or underwater ROV.

    Science.gov (United States)

    2010-10-01

    ...: Divers or underwater ROV. 115.650 Section 115.650 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... Alternative Hull Examination (AHE) Program options: Divers or underwater ROV. To complete your underwater survey, you may use divers or an underwater remotely operated vehicle (ROV). (a) If you use divers to...

  2. 78 FR 13869 - Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy...

    Science.gov (United States)

    2013-03-01

    ...-123-LNG; 12-128-NG; 12-148-NG; 12- 158-NG] Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; Puget Sound Energy, Inc.; CE FLNG, LLC; Consolidated...-NG Puget Sound Energy, Inc Order granting long- term authority to import/export natural gas from/to...

  3. Spectral measurements of underwater downwelling radiance of inland water bodies

    Directory of Open Access Journals (Sweden)

    Miguel Potes

    2013-11-01

    Full Text Available The apparatus exploited in this work is composed of an optical cable linked to a portable FieldSpec UV/VNIR that records the spectral downwelling radiance in underwater environment, allowing us to calculate the shortwave attenuation coefficient in water. Results for three inland water bodies are presented under different atmospheric conditions (sun zenith angle and wind speed and water composition (chlorophyll α concentration and turbidity. We show that the spectral downwelling zenith radiance profiles under high sun elevations present a positive slope in the upper layers due to relatively high scattering of direct sunlight compared to attenuation. For deeper layers, attenuation overcomes the scattering of sunlight leading to a constant negative logarithmic slope. For low sun elevations, a negative slope is observed in the entire water column since the scattering of direct sunlight is always lower than attenuation. Whenever a negative logarithmic constant slope is observed, the attenuation coefficient was computed. A relation was observed between attenuation coefficient in the photosynthetically active radiation (PAR spectral region and water turbidity, for the three water bodies under study.

  4. Underwater pipeline impact localization using piezoceramic transducers

    Science.gov (United States)

    Zhu, Junxiao; Ho, Siu Chun Michael; Patil, Devendra; Wang, Ning; Hirsch, Rachel; Song, Gangbing

    2017-10-01

    Reports indicated that impact events accounted for 47% of offshore pipeline failures, which calls for impact detection and localization for subsea pipelines. In this paper, an innovative method for rapid localization of impacts on underwater pipelines utilizing a novel determination technique for both arrival-time and group velocity (ATGV) of ultrasonic guided waves with lead zirconate titanate (PZT) transducers is described. PZT transducers mounted on the outer surface of a model pipeline were utilized to measure ultrasonic guided waves generated by impact events. Based on the signals from PZT sensors, the ATGV technique integrates wavelet decomposition, Hilbert transform and statistical analysis to pinpoint the arrival-time of the designated ultrasonic guided waves with a specific group velocity. Experimental results have verified the effectiveness and the localization accuracy for eight impact points along a model underwater pipeline. All estimations errors were small and were comparable with the wavelength of the designated ultrasonic guided waves. Furthermore, the method is robust against the low frequency structural vibration introduced by other external forces.

  5. GAS FLOW IN UNDERWATER BREATHING INSTALLATIONS

    Directory of Open Access Journals (Sweden)

    Anca CONSTANTIN

    2017-11-01

    Full Text Available The open circuit underwater breathing apparatus can be a one or two-stage regulator used in scuba diving or a two-stage regulator used in surface supplied installations. These installations are proper in underwater sites at small depth. The pneumatic circuit of a two-stage regulator is composed mainly of a first stage regulator mounted on the air cylinders and a second stage carried by the diver in his mouth. The two regulators are linked together by a medium pressure hose. The circuit opens when the depression created by the diver’s inhalation, in the second stage body, reaches a certain value. The second stage opening causes a transient movement, namely an expansion wave that propagates through the medium pressure hose to the first stage regulator. The first stage regulator opens and the air in the cylinders is allowed to flow to the diver. The longer the hose, the greater the duration of the expansion wave propagation. Investigations on the wave propagation offer data on the inspiration unsteady motion duration which influences the respiratory effort of the diver.

  6. An explanatory model of underwater adaptation

    Directory of Open Access Journals (Sweden)

    Joaquín Colodro

    Full Text Available The underwater environment is an extreme environment that requires a process of human adaptation with specific psychophysiological demands to ensure survival and productive activity. From the standpoint of existing models of intelligence, personality and performance, in this explanatory study we have analyzed the contribution of individual differences in explaining the adaptation of military personnel in a stressful environment. Structural equation analysis was employed to verify a model representing the direct effects of psychological variables on individual adaptation to an adverse environment, and we have been able to confirm, during basic military diving courses, the structural relationships among these variables and their ability to predict a third of the variance of a criterion that has been studied very little to date. In this way, we have confirmed in a sample of professionals (N = 575 the direct relationship of emotional adjustment, conscientiousness and general mental ability with underwater adaptation, as well as the inverse relationship of emotional reactivity. These constructs are the psychological basis for working under water, contributing to an improved adaptation to this environment and promoting risk prevention and safety in diving activities.

  7. Modelling cavitating flow around underwater missiles

    Directory of Open Access Journals (Sweden)

    Fabien Petitpas

    2011-12-01

    Full Text Available The diffuse interface model of Saurel et al. (2008 is used for the computation of compressible cavitating flows around underwater missiles. Such systems use gas injection and natural cavitation to reduce drag effects. Consequently material interfaces appear separating liquid and gas. These interfaces may have a really complex dynamics such that only a few formulations are able to predict their evolution. Contrarily to front tracking or interface reconstruction method the interfaces are computed as diffused numerical zones, that are captured in a routinely manner, as is done usually with gas dynamics solvers for shocks and contact discontinuity. With the present approach, a single set of partial differential equations is solved everywhere, with a single numerical scheme. This leads to very efficient solvers. The algorithm derived in Saurel et al. (2009 is used to compute cavitation pockets around solid bodies. It is first validated against experiments done in cavitation tunnel at CNU. Then it is used to compute flows around high speed underwater systems (Shkval-like missile. Performance data are then computed showing method ability to predict forces acting on the system.

  8. Hybrid Underwater Vehicle: ARV Design and Development

    Directory of Open Access Journals (Sweden)

    Zhigang DENG

    2014-02-01

    Full Text Available The development of SMU-I, a new autonomous & remotely-operated vehicle (ARV is described. Since it has both the characteristics of autonomous underwater vehicle (AUV and remote operated underwater vehicle (ROV, it is able to achieve precision fix station operation and manual timely intervention. In the paper the initial design of basic components, such as vehicle, propulsion, batteries etc. and the control design of motion are introduced and analyzed. ROV’s conventional cable is replaced by a fiber optic cable, which makes it available for high-bandwidth real-time video, data telemetry and high-quality teleoperation. Furthermore, with the aid of the manual real-time remote operation and ranging sonar, it also resolves the AUV’s conflicting issue, which can absolutely adapt the actual complex sea environment and satisfy the unknown mission need. The whole battery system is designed as two-battery banks, whose voltages and temperatures are monitored through CAN (controller area network bus to avoid battery fire and explosion. A fuzzy-PID controller is designed for its motion control, including depth control and direction control. The controller synthesizes the advantage of fuzzy control and PID control, utilizes the fuzzy rules to on-line tune the parameters of PID controller, and achieves a better control effect. Experiment results demonstrate to show the effectiveness of the test-bed.

  9. Software architecture of biomimetic underwater vehicle

    Science.gov (United States)

    Praczyk, Tomasz; Szymak, Piotr

    2016-05-01

    Autonomous underwater vehicles are vehicles that are entirely or partly independent of human decisions. In order to obtain operational independence, the vehicles have to be equipped with a specialized software. The main task of the software is to move the vehicle along a trajectory with collision avoidance. Moreover, the software has also to manage different devices installed on the vehicle board, e.g. to start and stop cameras, sonars etc. In addition to the software embedded on the vehicle board, the software responsible for managing the vehicle by the operator is also necessary. Its task is to define mission of the vehicle, to start, to stop the mission, to send emergency commands, to monitor vehicle parameters, and to control the vehicle in remotely operated mode. An important objective of the software is also to support development and tests of other software components. To this end, a simulation environment is necessary, i.e. simulation model of the vehicle and all its key devices, the model of the sea environment, and the software to visualize behavior of the vehicle. The paper presents architecture of the software designed for biomimetic autonomous underwater vehicle (BAUV) that is being constructed within the framework of the scientific project financed by Polish National Center of Research and Development.

  10. STABILITY OF UNDERWATER STRUCTURE UNDER WAVE ATTACK

    Directory of Open Access Journals (Sweden)

    C. Paotonan

    2012-02-01

    Full Text Available Geotube is, among others, a type of coastal structure that is increasingly accepted for coastal protection especially underwater breakwater. Besides its relatively low cost, it has other advantages such as flexibility, ease of construction and the fact that it can be filled with local sand material. Similar to all other coastal structures, it should also be stable under wave attack. A simple theoretical approach based on linear wave was adopted to estimate the stability of such structure. The theoretical solution was then compared with an experimental study. The experimental study was conducted at the Hydraulics and Hydrology Laboratory of Universitas Gadjah Mada. However, instead of a real geotube, PVC pipe was used where the weight of the PVC was varied by adjusting the volume of sand in the pipe. The result indicated that the agreement between the theoretical solution and the experiment was encouraging. The analytical solution may be utilized to predict underwater pipe stability under wave attack with certain degree of accuracy.

  11. Underwater noise levels in UK waters.

    Science.gov (United States)

    Merchant, Nathan D; Brookes, Kate L; Faulkner, Rebecca C; Bicknell, Anthony W J; Godley, Brendan J; Witt, Matthew J

    2016-11-10

    Underwater noise from human activities appears to be rising, with ramifications for acoustically sensitive marine organisms and the functioning of marine ecosystems. Policymakers are beginning to address the risk of ecological impact, but are constrained by a lack of data on current and historic noise levels. Here, we present the first nationally coordinated effort to quantify underwater noise levels, in support of UK policy objectives under the EU Marine Strategy Framework Directive (MSFD). Field measurements were made during 2013-2014 at twelve sites around the UK. Median noise levels ranged from 81.5-95.5 dB re 1 μPa for one-third octave bands from 63-500 Hz. Noise exposure varied considerably, with little anthropogenic influence at the Celtic Sea site, to several North Sea sites with persistent vessel noise. Comparison of acoustic metrics found that the RMS level (conventionally used to represent the mean) was highly skewed by outliers, exceeding the 97 th percentile at some frequencies. We conclude that environmental indicators of anthropogenic noise should instead use percentiles, to ensure statistical robustness. Power analysis indicated that at least three decades of continuous monitoring would be required to detect trends of similar magnitude to historic rises in noise levels observed in the Northeast Pacific.

  12. Computer simulations enhance experimental demonstrations in the underwater acoustics and sonar course

    Science.gov (United States)

    Korman, Murray S.

    2002-11-01

    Underwater acoustics and sonar (SP411) is a 3 hour course that is offered to midshipmen in their senior year. Typically, general science and oceanography majors, totaling 110 students/yr, enroll. Since this course is offered without a lab, the ''in class'' experience has been enhanced with the development (over many years) of our demo carts and computer workstations which surround the classroom. In a studio classroom atmosphere, students perform a variety of experiments in small groups. How can scientific visualizations best develop learning of complex interactions? Two examples are presented. PC-IMAT (personal curriculum interactive multisensor analysis training) simulations of multielement array steering support the theory and enhance the experiments that are performed in class such as the two-element array. Mathematica simulations involving the programming and animation of a point source in a rigid-rigid infinite parallel wave guide are used to stress the method of images, superposition, group and phase velocity and far-field modal pattern that is observed as a function of depth and source frequency. Later, students have fun using a ripple tank with an eye dropper to generate a point source between two adjustable parallel boundaries, and their understanding of ''underwater sound'' is greatly enhanced.

  13. A Speed Control Method for Underwater Vehicle under Hydraulic Flexible Traction

    OpenAIRE

    Zhao, Yin; Xia, Ying-kai; Chen, Ying; Xu, Guo-Hua

    2015-01-01

    Underwater vehicle speed control methodology method is the focus of research in this study. Driven by a hydraulic flexible traction system, the underwater vehicle advances steadily on underwater guide rails, simulating an underwater environment for the carried device. Considering the influence of steel rope viscoelasticity and the control system traction structure feature, a mathematical model of the underwater vehicle driven by hydraulic flexible traction system is established. A speed contr...

  14. Coral larvae move toward reef sounds.

    Directory of Open Access Journals (Sweden)

    Mark J A Vermeij

    Full Text Available Free-swimming larvae of tropical corals go through a critical life-phase when they return from the open ocean to select a suitable settlement substrate. During the planktonic phase of their life cycle, the behaviours of small coral larvae (<1 mm that influence settlement success are difficult to observe in situ and are therefore largely unknown. Here, we show that coral larvae respond to acoustic cues that may facilitate detection of habitat from large distances and from upcurrent of preferred settlement locations. Using in situ choice chambers, we found that settling coral larvae were attracted to reef sounds, produced mainly by fish and crustaceans, which we broadcast underwater using loudspeakers. Our discovery that coral larvae can detect and respond to sound is the first description of an auditory response in the invertebrate phylum Cnidaria, which includes jellyfish, anemones, and hydroids as well as corals. If, like settlement-stage reef fish and crustaceans, coral larvae use reef noise as a cue for orientation, the alleviation of noise pollution in the marine environment may gain further urgency.

  15. Underwater television camera for monitoring inner side of pressure vessel

    International Nuclear Information System (INIS)

    Takayama, Kazuhiko.

    1997-01-01

    An underwater television support device equipped with a rotatable and vertically movable underwater television camera and an underwater television camera controlling device for monitoring images of the inside of the reactor core photographed by the underwater television camera to control the position of the underwater television camera and the underwater light are disposed on an upper lattice plate of a reactor pressure vessel. Both of them are electrically connected with each other by way of a cable to rapidly observe the inside of the reactor core by the underwater television camera. The reproducibility is extremely satisfactory by efficiently concentrating the position of the camera and image information upon inspection and observation. As a result, the steps for periodical inspection can be reduced to shorten the days for the periodical inspection. Since there is no requirement to withdraw fuel assemblies over a wide reactor core region, and the device can be used with the fuel assemblies being left as they are in the reactor, it is suitable for inspection of detectors for nuclear instrumentation. (N.H.)

  16. Underwater fiber-wireless communication with a passive front end

    Science.gov (United States)

    Xu, Jing; Sun, Bin; Lyu, Weichao; Kong, Meiwei; Sarwar, Rohail; Han, Jun; Zhang, Wei; Deng, Ning

    2017-11-01

    We propose and experimentally demonstrate a novel concept on underwater fiber-wireless (Fi-Wi) communication system with a fully passive wireless front end. A low-cost step-index (SI) plastic optical fiber (POF) together with a passive collimating lens at the front end composes the underwater Fi-Wi architecture. We have achieved a 1.71-Gb/s transmission at a mean BER of 4.97 × 10-3 (1.30 × 10-3 when using power loading) over a 50-m SI-POF and 2-m underwater wireless channel using orthogonal frequency division multiplexing (OFDM). Although the wireless part is very short, it actually plays a crucial role in practical underwater implementation, especially in deep sea. Compared with the wired solution (e.g. using a 52-m POF cable without the UWOC part), the proposed underwater Fi-Wi scheme can save optical wet-mate connectors that are sophisticated, very expensive and difficult to install in deep ocean. By combining high-capacity robust POF with the mobility and ubiquity of underwater wireless optical communication (UWOC), the proposed underwater Fi-Wi technology will find wide application in ocean exploration.

  17. Towards a Hybrid Approach to Context Reasoning for Underwater Robots

    Directory of Open Access Journals (Sweden)

    Xin Li

    2017-02-01

    Full Text Available Ontologies have been widely used to facilitate semantic interoperability and serve as a common information model in many applications or domains. The Smart and Networking Underwater Robots in Cooperation Meshes (SWARMs project, aiming to facilitate coordination and cooperation between heterogeneous underwater vehicles, also adopts ontologies to formalize information that is necessarily exchanged between vehicles. However, how to derive more useful contexts based on ontologies still remains a challenge. In particular, the extreme nature of the underwater environment introduces uncertainties in context data, thus imposing more difficulties in context reasoning. None of the existing context reasoning methods could individually deal with all intricacies in the underwater robot field. To this end, this paper presents the first proposal applying a hybrid context reasoning mechanism that includes ontological, rule-based, and Multi-Entity Bayesian Network (MEBN reasoning methods to reason about contexts and their uncertainties in the underwater robot field. The theoretical foundation of applying this reasoning mechanism in underwater robots is given by a case study on the oil spill monitoring. The simulated reasoning results are useful for further decision-making by operators or robots and they show that the consolidation of different reasoning methods is a promising approach for context reasoning in underwater robots.

  18. Underwater photography - A visual survey method

    Digital Repository Service at National Institute of Oceanography (India)

    Sharma, R.

    . Calculation of the area photographed on the seafloor (X= altitude of the camera, L= length of the photograph, B= breadth of the photograph, LxB=Area of the photograph) Fig. 3. Calculation of scale factor data and sounding data, need...: Hersey, J.B. (Ed.) Deep sea photography. The Johns Hopkins Press: Baltimore, 43-45 Photo data Navigation data Sounding data Processing seafloor/ sub-bottom features Correction / projection Interpolation Of position Estimation of water depth...

  19. The Textile Form of Sound

    DEFF Research Database (Denmark)

    Bendixen, Cecilie

    of sound. This issue is a part of a Ph.D. study at The Danish Design School in Copenhagen. Sound diffusion in architecture is a complex phenomenon. From the sound source the sound spreads in all directions as a sphere of wave fronts. When the sound is reflected from room boundaries or furniture, complex......Sound is a part of architecture, and sound is complex. Upon this, sound is invisible. How is it then possible to design visual objects that interact with the sound? This paper addresses the problem of how to get access to the complexity of sound and how to make textile material revealing the form...

  20. Behavioral responses of a harbor porpoise (Phocoena phocoena) to playbacks of broadband pile driving sounds.

    Science.gov (United States)

    Kastelein, Ronald A; van Heerden, Dorianne; Gransier, Robin; Hoek, Lean

    2013-12-01

    The high under-water sound pressure levels (SPLs) produced during pile driving to build offshore wind turbines may affect harbor porpoises. To estimate the discomfort threshold of pile driving sounds, a porpoise in a quiet pool was exposed to playbacks (46 strikes/min) at five SPLs (6 dB steps: 130-154 dB re 1 μPa). The spectrum of the impulsive sound resembled the spectrum of pile driving sound at tens of kilometers from the pile driving location in shallow water such as that found in the North Sea. The animal's behavior during test and baseline periods was compared. At and above a received broadband SPL of 136 dB re 1 μPa [zero-peak sound pressure level: 151 dB re 1 μPa; t90: 126 ms; sound exposure level of a single strike (SELss): 127 dB re 1 μPa(2) s] the porpoise's respiration rate increased in response to the pile driving sounds. At higher levels, he also jumped out of the water more often. Wild porpoises are expected to move tens of kilometers away from offshore pile driving locations; response distances will vary with context, the sounds' source level, parameters influencing sound propagation, and background noise levels. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. A Secure Communication Suite for Underwater Acoustic Sensor Networks

    Directory of Open Access Journals (Sweden)

    Angelica Lo Duca

    2012-11-01

    Full Text Available In this paper we describe a security suite for Underwater Acoustic Sensor Networks comprising both fixed and mobile nodes. The security suite is composed of a secure routing protocol and a set of cryptographic primitives aimed at protecting the confidentiality and the integrity of underwater communication while taking into account the unique characteristics and constraints of the acoustic channel. By means of experiments and simulations based on real data, we show that the suite is suitable for an underwater networking environment as it introduces limited, and sometimes negligible, communication and power consumption overhead.

  2. Application of YAG laser processing in underwater welding and cutting

    International Nuclear Information System (INIS)

    Ohwaki, Katsura; Morita, Ichiro; Kojima, Toshio; Sato, Shuichi

    2002-01-01

    The high-power YAG laser is a new fabrication tool. The laser torch is easy to combine with complex with complex mechanics because of beam delivery through optical fiber. A direct underwater laser welding technology has been developed and applied to the preservation, maintenance and removal of nuclear power plants. For subdividing or removing operations for retirement of plants, the laser cutting properties were confirmed to allow a maximum cutting thickness of 80 mm. For repairing inner surface of stainless steel tanks, an underwater laser welding system using a remote-controlled robot was developed and the high quality of underwater laser welding was confirmed. (author)

  3. Centralised versus Decentralised Control Reconfiguration for Collaborating Underwater Robots

    DEFF Research Database (Denmark)

    Furno, Lidia; Nielsen, Mikkel Cornelius; Blanke, Mogens

    2015-01-01

    The present paper introduces an approach to fault-tolerant reconfiguration for collaborating underwater robots. Fault-tolerant reconfiguration is obtained using the virtual actuator approach, Steen (2005). The paper investigates properties of a centralised versus a decentralised implementation...... an underwater drill needs to be transported and positioned by three collaborating robots as part of an underwater autonomous operation....... and assesses the capabilities under communication constraints between the individual robots. In the centralised case, each robot sends information related to its own status to a unique virtual actuator that computes the necessary reconfiguration. In the decentralised case, each robot is equipped with its own...

  4. Adaptive Decentralized Control of Mobile Underwater Sensor Networks and Robots for Modeling Underwater Phenomena

    Directory of Open Access Journals (Sweden)

    Carrick Detweiler

    2014-05-01

    Full Text Available Understanding the dynamics of bodies of water and their impact on the global environment requires sensing information over the full volume of water. In this article, we develop a gradient-based decentralized controller that dynamically adjusts the depth of a network of underwater sensors to optimize sensing for computing maximally detailed volumetric models. We prove that the controller converges to a local minimum and show how the controller can be extended to work with hybrid robot and sensor network systems. We implement the controller on an underwater sensor network with depth adjustment capabilities. Through simulations and in-situ experiments, we verify the functionality and performance of the system and algorithm.

  5. Vocalisation Repertoire of Female Bluefin Gurnard (Chelidonichthys kumu in Captivity: Sound Structure, Context and Vocal Activity.

    Directory of Open Access Journals (Sweden)

    Craig A Radford

    Full Text Available Fish vocalisation is often a major component of underwater soundscapes. Therefore, interpretation of these soundscapes requires an understanding of the vocalisation characteristics of common soniferous fish species. This study of captive female bluefin gurnard, Chelidonichthys kumu, aims to formally characterise their vocalisation sounds and daily pattern of sound production. Four types of sound were produced and characterised, twice as many as previously reported in this species. These sounds fit two aural categories; grunt and growl, the mean peak frequencies for which ranged between 129 to 215 Hz. This species vocalized throughout the 24 hour period at an average rate of (18.5 ± 2.0 sounds fish-1 h-1 with an increase in vocalization rate at dawn and dusk. Competitive feeding did not elevate vocalisation as has been found in other gurnard species. Bluefin gurnard are common in coastal waters of New Zealand, Australia and Japan and, given their vocalization rate, are likely to be significant contributors to ambient underwater soundscape in these areas.

  6. Sound Insulation between Dwellings

    DEFF Research Database (Denmark)

    Rasmussen, Birgit

    2011-01-01

    Regulatory sound insulation requirements for dwellings exist in more than 30 countries in Europe. In some countries, requirements have existed since the 1950s. Findings from comparative studies show that sound insulation descriptors and requirements represent a high degree of diversity...... and initiate – where needed – improvement of sound insulation of new and existing dwellings in Europe to the benefit of the inhabitants and the society. A European COST Action TU0901 "Integrating and Harmonizing Sound Insulation Aspects in Sustainable Urban Housing Constructions", has been established and runs...... 2009-2013. The main objectives of TU0901 are to prepare proposals for harmonized sound insulation descriptors and for a European sound classification scheme with a number of quality classes for dwellings. Findings from the studies provide input for the discussions in COST TU0901. Data collected from 24...

  7. Task Allocation and Path Planning for Collaborative Autonomous Underwater Vehicles Operating through an Underwater Acoustic Network

    Directory of Open Access Journals (Sweden)

    Yueyue Deng

    2013-01-01

    Full Text Available Dynamic and unstructured multiple cooperative autonomous underwater vehicle (AUV missions are highly complex operations, and task allocation and path planning are made significantly more challenging under realistic underwater acoustic communication constraints. This paper presents a solution for the task allocation and path planning for multiple AUVs under marginal acoustic communication conditions: a location-aided task allocation framework (LAAF algorithm for multitarget task assignment and the grid-based multiobjective optimal programming (GMOOP mathematical model for finding an optimal vehicle command decision given a set of objectives and constraints. Both the LAAF and GMOOP algorithms are well suited in poor acoustic network condition and dynamic environment. Our research is based on an existing mobile ad hoc network underwater acoustic simulator and blind flooding routing protocol. Simulation results demonstrate that the location-aided auction strategy performs significantly better than the well-accepted auction algorithm developed by Bertsekas in terms of task-allocation time and network bandwidth consumption. We also demonstrate that the GMOOP path-planning technique provides an efficient method for executing multiobjective tasks by cooperative agents with limited communication capabilities. This is in contrast to existing multiobjective action selection methods that are limited to networks where constant, reliable communication is assumed to be available.

  8. Sound absorption of snow

    OpenAIRE

    Maysenhölder, W.; Schneebeli, M.; Zhou, X.; Zhang, T.; Heggli, M.

    2008-01-01

    Recently fallen snow possesses good sound-absorbing properties. This fact is well-known and confirmed by measurements. Is the filigree structure of snowflakes decisive? In principle we know that the sound-absorbing capacity of a porous material is dependent on its structure. But until now the question as to which structural characteristics are significant has been insufficiently answered. Detailed investigations of snow are to explain this fact by precise measurements of the sound absorption,...

  9. Monitoring and crisis system of radiation safety

    International Nuclear Information System (INIS)

    Bartok, J.; Borovansky, P.; Macica, J.; Petrovicova, M.

    2005-01-01

    In this paper we have briefly described our practical experiences with the most complex Radiation Monitoring System we have designed. This system consists of number of stations; those data are collected in the main crisis center of the whole system. The main center integrates RMS Central Database, the IMS Model Suite workstation and the Graphics workstation. The radiations probes of the RP series are the base for stationary , portable sets and for sets measuring underwater radiation. The radiation and meteorological data, which are necessary for reasonable interpretation of radiation data, are archived in RMS Central database. The Lagrangian trajectory model from the IMS Model Suite serves for radiation dispersion modeling. (authors)

  10. Status of the ANTARES underwater neutrino telescope

    CERN Document Server

    Hallewell, G D

    2003-01-01

    The ANTARES Collaboration is constructing a deep underwater neutrino detector for operation at -2400 m off the French Mediterranean coast near Toulon. The detector, which will begin operation in 2004, will have an aperture of approx 0.1 km sup 2 , and will contain 900 photomultiplier tubes. The photomultiplier axes will be angled 45 deg. downward toward the seabed to observe the Cherenkov emissions of upward-going muons created by the interactions in or near the detector of high energy neutrinos traversing the Earth. These neutrinos arrive undeviated from a variety of galactic and extragalactic sources of astrophysical interest, and might be produced in the possible annihilation of dark matter neutralinos. The design and present status of the detector are summarized. Results from site evaluation and the development of supporting instrumentation are outlined.

  11. The NESTOR underwater neutrino telescope project

    Energy Technology Data Exchange (ETDEWEB)

    Rapidis, Petros A. [Institute of Nuclear Physics, National Center for Scientific Research ' Demokritos' , Athens 15310 (Greece)], E-mail: rapidis@inp.demokritos.gr

    2009-04-11

    The NESTOR collaboration is continuing its efforts towards deploying an underwater neutrino telescope. Further site studies (e.g. water light transmission measurements, sedimentation rates, etc.) are being carried out within the context of characterizing a site that may host the proposed KM3NeT infrastructure. In addition, following the successful deployment of a single floor of a NESTOR tower in 2003, five floors are now in the final stages of preparation. The use of these five floors in a form of a truncated tower together with four autonomous strings to be located some 300 m away from the tower is being contemplated. This arrangement, named NuBE (for Neutrino Burst Experiment), that may allow the detection neutrinos in coincidence with Gamma Ray Bursts, will be described.

  12. A Validation Process for Underwater Localization Algorithms

    Directory of Open Access Journals (Sweden)

    Marc Hildebrandt

    2014-09-01

    Full Text Available This paper describes the validation process of a localization algorithm for underwater vehicles. In order to develop new localization algorithms, it is essential to characterize them with regard to their accuracy, long-term stability and robustness to external sources of noise. This is only possible if a gold-standard reference localization (GSRL is available against which any new localization algorithm (NLA can be tested. This process requires a vehicle which carries all the required sensor and processing systems for both the GSRL and the NLA. This paper will show the necessity of such a validation process, briefly sketch the test vehicle and its capabilities, describe the challenges in computing the localizations of both the GSRL and the NLA simultaneously for comparison, and conclude with experimental data of real-world trials.

  13. Improved Underwater Excitation-Emission Matrix Fluorometer

    Science.gov (United States)

    Moore, Casey; daCunha, John; Rhoades, Bruce; Twardowski, Michael

    2007-01-01

    A compact, high-resolution, two-dimensional excitation-emission matrix fluorometer (EEMF) has been designed and built specifically for use in identifying and measuring the concentrations of organic compounds, including polluting hydrocarbons, in natural underwater settings. Heretofore, most EEMFs have been designed and built for installation in laboratories, where they are used to analyze the contents of samples collected in the field and brought to the laboratories. Because the present EEMF can be operated in the field, it is better suited to measurement of spatially and temporally varying concentrations of substances of interest. In excitation-emission matrix (EEM) fluorometry, fluorescence is excited by irradiating a sample at one or more wavelengths, and the fluorescent emission from the sample is measured at multiple wavelengths. When excitation is provided at only one wavelength, the technique is termed one-dimensional (1D) EEM fluorometry because the resulting matrix of fluorescence emission data (the EEM) contains only one row or column. When excitation is provided at multiple wavelengths, the technique is termed two-dimensional (2D) EEM fluorometry because the resulting EEM contains multiple rows and columns. EEM fluorometry - especially the 2D variety - is well established as a means of simultaneously detecting numerous dissolved and particulate compounds in water. Each compound or pool of compounds has a unique spectral fluorescence signature, and each EEM is rich in information content, in that it can contain multiple fluorescence signatures. By use of deconvolution and/or other mixture-analyses techniques, it is often possible to isolate the spectral signature of compounds of interest, even when their fluorescence spectra overlap. What distinguishes the present 2D EEMF over prior laboratory-type 2D EEMFs are several improvements in packaging (including a sealed housing) and other aspects of design that render it suitable for use in natural underwater

  14. Adaptive control of nonlinear underwater robotic systems

    Directory of Open Access Journals (Sweden)

    Thor I. Fossen

    1991-04-01

    Full Text Available The problem of controlling underwater mobile robots in 6 degrees of freedom (DOF is addressed. Uncertainties in the input matrix due to partly known nonlinear thruster characteristics are modeled as multiplicative input uncertainty. This paper proposes two methods to compensate for the model uncertainties: (1 an adaptive passivity-based control scheme and (2 deriving a hybrid (adaptive and sliding controller. The hybrid controller consists of a switching term which compensates for uncertainties in the input matrix and an on-line parameter estimation algorithm. Global stability is ensured by applying Barbalat's Lyapunovlike lemma. The hybrid controller is simulated for the horizontal motion of the Norwegian Experimental Remotely Operated Vehicle (NEROV.

  15. Collision Detection for Underwater ROV Manipulator Systems.

    Science.gov (United States)

    Sivčev, Satja; Rossi, Matija; Coleman, Joseph; Omerdić, Edin; Dooly, Gerard; Toal, Daniel

    2018-04-06

    Work-class ROVs equipped with robotic manipulators are extensively used for subsea intervention operations. Manipulators are teleoperated by human pilots relying on visual feedback from the worksite. Operating in a remote environment, with limited pilot perception and poor visibility, manipulator collisions which may cause significant damage are likely to happen. This paper presents a real-time collision detection algorithm for marine robotic manipulation. The proposed collision detection mechanism is developed, integrated into a commercial ROV manipulator control system, and successfully evaluated in simulations and experimental setup using a real industry standard underwater manipulator. The presented collision sensing solution has a potential to be a useful pilot assisting tool that can reduce the task load, operational time, and costs of subsea inspection, repair, and maintenance operations.

  16. The NESTOR underwater neutrino telescope project

    International Nuclear Information System (INIS)

    Rapidis, Petros A.

    2009-01-01

    The NESTOR collaboration is continuing its efforts towards deploying an underwater neutrino telescope. Further site studies (e.g. water light transmission measurements, sedimentation rates, etc.) are being carried out within the context of characterizing a site that may host the proposed KM3NeT infrastructure. In addition, following the successful deployment of a single floor of a NESTOR tower in 2003, five floors are now in the final stages of preparation. The use of these five floors in a form of a truncated tower together with four autonomous strings to be located some 300 m away from the tower is being contemplated. This arrangement, named NuBE (for Neutrino Burst Experiment), that may allow the detection neutrinos in coincidence with Gamma Ray Bursts, will be described.

  17. Ontogenetic investigation of underwater hearing capabilities in loggerhead sea turtles (Caretta caretta) using a dual testing approach.

    Science.gov (United States)

    Lavender, Ashley L; Bartol, Soraya M; Bartol, Ian K

    2014-07-15

    Sea turtles reside in different acoustic environments with each life history stage and may have different hearing capacity throughout ontogeny. For this study, two independent yet complementary techniques for hearing assessment, i.e. behavioral and electrophysiological audiometry, were employed to (1) measure hearing in post-hatchling and juvenile loggerhead sea turtles Caretta caretta (19-62 cm straight carapace length) to determine whether these migratory turtles exhibit an ontogenetic shift in underwater auditory detection and (2) evaluate whether hearing frequency range and threshold sensitivity are consistent in behavioral and electrophysiological tests. Behavioral trials first required training turtles to respond to known frequencies, a multi-stage, time-intensive process, and then recording their behavior when they were presented with sound stimuli from an underwater speaker using a two-response forced-choice paradigm. Electrophysiological experiments involved submerging restrained, fully conscious turtles just below the air-water interface and recording auditory evoked potentials (AEPs) when sound stimuli were presented using an underwater speaker. No significant differences in behavior-derived auditory thresholds or AEP-derived auditory thresholds were detected between post-hatchling and juvenile sea turtles. While hearing frequency range (50-1000/1100 Hz) and highest sensitivity (100-400 Hz) were consistent in audiograms pooled by size class for both behavior and AEP experiments, both post-hatchlings and juveniles had significantly higher AEP-derived than behavior-derived auditory thresholds, indicating that behavioral assessment is a more sensitive testing approach. The results from this study suggest that post-hatchling and juvenile loggerhead sea turtles are low-frequency specialists, exhibiting little differences in threshold sensitivity and frequency bandwidth despite residence in acoustically distinct environments throughout ontogeny. © 2014

  18. Morphing hull implementation for unmanned underwater vehicles

    International Nuclear Information System (INIS)

    Miller, Timothy F; Gandhi, Farhan; Rufino, Russell J

    2013-01-01

    There has been much interest and work in the area of morphing aircraft since the 1980s. Morphing could also potentially benefit unmanned underwater vehicles (UUVs). The current paper envisions a UUV with an interior pressure hull and a variable diameter outer flexible hull with fuel stored in the annulus between, and presents a mechanism to realize diameter change of the outer hull. The outer hull diameter of UUVs designed for very long endurance/range could be progressively reduced as fuel was consumed, thereby reducing drag and further increasing endurance and range capability. Diameter morphing could also be advantageous for compact storage of UUVs. A prototype is fabricated to represent an axial section of such a morphing diameter UUV. Diameter change is achieved using eight morphing trusses arranged equidistant around the circumference of the representative interior rigid hull. Each morphing truss has a lower rail (attached to the rigid hull) and an upper rail with V-linkages between, at either ends of the rail. Horizontal motion of the feet of the V-linkages (sliding in the lower rail) results in vertical motion of the upper rail which in turn produces diameter change of the outer hull. For the prototype built and tested, a 63% increase in outer diameter from 12.75″ to 20.75″ was achieved. The introduction of a stretched latex representative flexible skin around the outer rails increased actuation force requirement and led to a propensity for the wheel-in-track sliders in the morphing truss to bind. It is anticipated that this could be overcome with higher precision manufacturing. In addition to symmetric actuation of the morphing trusses resulting in diameter change, the paper also shows that with asymmetric actuation the hull cross-section shape can be changed (for example, from a circular section for underwater operation to a V-section for surface operations). (paper)

  19. On sampling the ocean using underwater gliders

    Science.gov (United States)

    Rudnick, Daniel L.; Cole, Sylvia T.

    2011-08-01

    The sampling characteristics of an underwater glider are addressed through comparison with contemporaneous measurements from a ship survey using a towed vehicle. The comparison uses the underwater glider Spray and the towed vehicle SeaSoar north of Hawaii along 158°W between 22.75°N and 34.5°N. A Spray dive from the surface to 1000 m and back took 5.6 h and covered 5.3 km, resulting in a horizontal speed of 0.26 m s-1. SeaSoar undulated between the surface and 400 m, completing a cycle in 11 min while covering 2.6 km, for a speed of 3.9 m s-1. Adjacent profiles of temperature and salinity are compared between the two platforms to prove that each is accurate. Spray and SeaSoar data are compared through sections, isopycnal spatial series, and wave number spectra. The relative slowness of the glider results in the projection of high-frequency oceanic variability, such as internal waves, onto spatial structure. The projection is caused by Doppler smearing because of finite speed and aliasing due to discrete sampling. The projected variability is apparent in properties measured on depth surfaces or in isopycnal depth. No projected variability is seen in observations of properties on constant density surfaces because internal waves are intrinsically filtered. Wave number spectra suggest that projected variability affects properties at constant depth at wavelengths shorter than 30 km. These results imply that isobaric quantities, like geostrophic shear, are valid at wavelengths longer than 30 km, while isopycnal quantities, like spice, may be analyzed for scales as small as a glider measures.

  20. Short Communication Evaluation of an underwater biopsy probe for ...

    African Journals Online (AJOL)

    lethal methods may become an increasingly useful tool to investigate shark populations where researchers encounter logistical or conservation-related constraints. Keywords: biopsy probe, laser photogrammetry, non-lethal sampling, underwater ...

  1. Digital sonar design in underwater acoustics principles and applications

    CERN Document Server

    Li, Qihu

    2012-01-01

    "Digital Sonar Design in Underwater Acoustics Principles and Applications" provides comprehensive and up-to-date coverage of research on sonar design, including the basic theory and techniques of digital signal processing, basic concept of information theory, ocean acoustics, underwater acoustic signal propagation theory, and underwater signal processing theory. This book discusses the general design procedure and approaches to implementation, the design method, system simulation theory and techniques, sonar tests in the laboratory, lake and sea, and practical validation criteria and methods for digital sonar design. It is intended for researchers in the fields of underwater signal processing and sonar design, and also for navy officers and ocean explorers. Qihu Li is a professor at the Institute of Acoustics, Chinese Academy of Sciences, and an academician of the Chinese Academy of Sciences.

  2. Automated Underwater Image Restoration and Retrieval of Related Optical Properties

    National Research Council Canada - National Science Library

    Hou, Weilin; Gray, Deric J; Weidemann, Alan D; Fournier, Georges R; Forand, J. L

    2007-01-01

    ...) in the spatial domain and the modulation transfer function (MTF) in the frequency domain. Due to the intensity variations involved in underwater sensing, denoising is carefully carried out by wavelet decompositions...

  3. Wireless Underwater Monitoring Systems Based on Energy Harvestings

    Directory of Open Access Journals (Sweden)

    Sea-Hee HWANGBO

    2013-01-01

    Full Text Available One of the important research fields for aquatic exploitation and conservation is underwater wireless sensor network. Since limited energy source for underwater nodes and devices is a main open problem, in this paper, we propose wireless underwater monitoring systems powered by energy harvester which resolves the energy constraint. The target system generates renewable energy from energy harvester and shares the energy with underwater sensor nodes. For the realization of the system, key components to be investigated are discriminated as follows: acoustic modem, actuator, smart battery charge controller, energy harvester and wireless power transfer module. By developing acoustic modem, actuator and smart battery charge controller and utilizing off-the-shelf energy harvester and wireless power transfer module, we design and implement a prototype of the system. Also, we verify the feasibility of concept of target system by conducting indoor and outdoor experiments.

  4. Trade-off Analysis of Underwater Acoustic Sensor Networks

    Science.gov (United States)

    Tuna, G.; Das, R.

    2017-09-01

    In the last couple of decades, Underwater Acoustic Sensor Networks (UASNs) were started to be used for various commercial and non-commercial purposes. However, in underwater environments, there are some specific inherent constraints, such as high bit error rate, variable and large propagation delay, limited bandwidth capacity, and short-range communications, which severely degrade the performance of UASNs and limit the lifetime of underwater sensor nodes as well. Therefore, proving reliability of UASN applications poses a challenge. In this study, we try to balance energy consumption of underwater acoustic sensor networks and minimize end-to-end delay using an efficient node placement strategy. Our simulation results reveal that if the number of hops is reduced, energy consumption can be reduced. However, this increases end-to-end delay. Hence, application-specific requirements must be taken into consideration when determining a strategy for node deployment.

  5. Object detection from images obtained through underwater turbulence medium

    Science.gov (United States)

    Furhad, Md. Hasan; Tahtali, Murat; Lambert, Andrew

    2017-09-01

    Imaging through underwater experiences severe distortions due to random fluctuations of temperature and salinity in water, which produces underwater turbulence through diffraction limited blur. Lights reflecting from objects perturb and attenuate contrast, making the recognition of objects of interest difficult. Thus, the information available for detecting underwater objects of interest becomes a challenging task as they have inherent confusion among the background, foreground and other image properties. In this paper, a saliency-based approach is proposed to detect the objects acquired through an underwater turbulent medium. This approach has drawn attention among a wide range of computer vision applications, such as image retrieval, artificial intelligence, neuro-imaging and object detection. The image is first processed through a deblurring filter. Next, a saliency technique is used on the image for object detection. In this step, a saliency map that highlights the target regions is generated and then a graph-based model is proposed to extract these target regions for object detection.

  6. Filming Underwater in 3d Respecting Stereographic Rules

    Science.gov (United States)

    Rinaldi, R.; Hordosch, H.

    2015-04-01

    After an experimental phase of many years, 3D filming is now effective and successful. Improvements are still possible, but the film industry achieved memorable success on 3D movie's box offices due to the overall quality of its products. Special environments such as space ("Gravity") and the underwater realm look perfect to be reproduced in 3D. "Filming in space" was possible in "Gravity" using special effects and computer graphic. The underwater realm is still difficult to be handled. Underwater filming in 3D was not that easy and effective as filming in 2D, since not long ago. After almost 3 years of research, a French, Austrian and Italian team realized a perfect tool to film underwater, in 3D, without any constrains. This allows filmmakers to bring the audience deep inside an environment where they most probably will never have the chance to be.

  7. Collision Avoidance of Moving Obstacles for Underwater Robots

    Directory of Open Access Journals (Sweden)

    KWON KYOUNG YOUB

    2006-10-01

    Full Text Available A fuzzy logic for autonomous navigation of underwater robot is proposed in this paper. The VFF(Virtual Force Field algorithm, which is widely used in the field of mobile robot, is modified for application to the autonomous navigation of underwater robot. This Modified Virtual Force Field(MVFF algorithm using the fuzzy logic can be used in either track keeping or obstacle avoidance. Fuzzy logics are devised to handle various situations which can be faced during autonomous navigation of underwater robot. A graphic simulator based on OpenGL for an autonomous navigation has been developed. The good performance of the proposed MVFF algorithm is verified through computer simulations on an underwater robot.

  8. Multi-layer protective armour for underwater shock wave mitigation

    Directory of Open Access Journals (Sweden)

    Ahmed Hawass

    2015-12-01

    The strain gauge data and displacement sensors results showed that the multi-layer plates have higher level of underwater shock wave mitigation than the triple aluminum plates with strain and deflection of nearly 50%.

  9. Underwater image enhancement through depth estimation based on random forest

    Science.gov (United States)

    Tai, Shen-Chuan; Tsai, Ting-Chou; Huang, Jyun-Han

    2017-11-01

    Light absorption and scattering in underwater environments can result in low-contrast images with a distinct color cast. This paper proposes a systematic framework for the enhancement of underwater images. Light transmission is estimated using the random forest algorithm. RGB values, luminance, color difference, blurriness, and the dark channel are treated as features in training and estimation. Transmission is calculated using an ensemble machine learning algorithm to deal with a variety of conditions encountered in underwater environments. A color compensation and contrast enhancement algorithm based on depth information was also developed with the aim of improving the visual quality of underwater images. Experimental results demonstrate that the proposed scheme outperforms existing methods with regard to subjective visual quality as well as objective measurements.

  10. Navigation of autonomous underwater vehicle using extended kalman filter

    Digital Repository Service at National Institute of Oceanography (India)

    Ranjan, T.N.; Nherakkol, A.; Navelkar, G.S.

    To navigate the Autonomous Underwater Vehicle (AUV) accurately is one of the most important aspects in its application. A truly autonomous vehicle must determine its position which requires the optimal integration of all available attitude...

  11. Euclidean reconstruction of natural underwater scenes using optic imagery sequence

    Science.gov (United States)

    Hu, Han

    The development of maritime applications require monitoring, studying and preserving of detailed and close observation on the underwater seafloor and objects. Stereo vision offers advanced technologies to build 3D models from 2D still overlapping optic images in a relatively inexpensive way. However, while image stereo matching is a necessary step in 3D reconstruction procedure, even the most robust dense matching techniques are not guaranteed to work for underwater images due to the challenging aquatic environment. In this thesis, in addition to a detailed introduction and research on the key components of building 3D models from optic images, a robust modified quasi-dense matching algorithm based on correspondence propagation and adaptive least square matching for underwater images is proposed and applied to some typical underwater image datasets. The experiments demonstrate the robustness and good performance of the proposed matching approach.

  12. Increasing the efficiency of thermoacoustic carbon nanotube sound projectors.

    Science.gov (United States)

    Aliev, Ali E; Gartstein, Yuri N; Baughman, Ray H

    2013-06-14

    Carbon nanotubes (CNTs) can generate smooth-spectra sound emission over a wide frequency range (1-10(5) Hz) by means of thermoacoustics (TA). However, in the low frequencies f, where the need for large area sound projectors is high, the sound generation efficiency η of open CNT sheets is low, since η [proportionality] f(2). Together with this problem, the nanoscale thickness of CNT sheets, their high sensitivity to the environment and the high surface temperatures useful for TA sound generation are other drawbacks, which we address here by protective encapsulation of free-standing CNT sheets in inert gases. We provide an extensive experimental study of such closed systems for different thermodynamic regimes and rationalize our observations within a basic theoretical framework. The observed sound pressure levels for encapsulated argon filled TA transducers (130 dB in air and 200 dB underwater in the near field at 5 cm distance, and 100 and 170 dB in the far field at 1 m distance) are Q times higher than those for open systems, where Q is the resonant quality factor of the thin enclosure plates. Moreover, the sound generation efficiency of the encapsulated system increases toward low frequencies (η [proportionality] 1/f(2)). Another method to increase η in the low frequency region is by modulation of the applied high frequency carrier current with a low frequency resonant envelope. This approach enables sound generation at the frequency of the applied current without the need for additional energy-consuming biasing. The acoustical and geometrical parameters providing further increases in efficiency and transduction performance for resonant systems are discussed.

  13. The Textile Form of Sound

    DEFF Research Database (Denmark)

    Bendixen, Cecilie

    three-dimensional geometries of interfering spheres are created. Textiles are generally a very good sound dampening material. To dampen the sound most effective it should be placed where the sound energy is highest. To find these invisible spots of energy and to reveal the geometry of them, two......Sound is a part of architecture, and sound is complex. Upon this, sound is invisible. How is it then possible to design visual objects that interact with the sound? This paper addresses the problem of how to get access to the complexity of sound and how to make textile material revealing the form...... of sound. This issue is a part of a Ph.D. study at The Danish Design School in Copenhagen. Sound diffusion in architecture is a complex phenomenon. From the sound source the sound spreads in all directions as a sphere of wave fronts. When the sound is reflected from room boundaries or furniture, complex...

  14. Underwater acoustic communications. From point-to-point to networks

    OpenAIRE

    Jesus, S. M.

    2013-01-01

    This is a review presentation that addresses recent developments in underwater acoustic telemetry as a tool for ocean observation, monitoring and protection. Distributed sensing is a paradigm with important reflections in oceanic technology where bottom installed structures can not always be connected to a central hub through cabled networks. Moreover, recent developments in ocean robotics lead to the off-the-shelf availability of autonomous underwater vehicles that rely on wireless communica...

  15. Estimation of underwater acoustic fields at high frequencies

    OpenAIRE

    Temsamani, A.B.; Vandenplas, S.; Van Biesen, L.

    2001-01-01

    In this work a parametric modeling of the underwater acoustic field is investigated in a laboratory scale at high frequencies (150-850 kHz). The aim is to develop experimentally verifiable theoretical models to investigate the acoustic field propagation in elastic and viscoelastic or porous media. To achieve this goal, the efforts have been directed to three integral parts pertaining to the development of the methods. The first part deals with the modeling of the underwater acoustic field fol...

  16. Strong tracking adaptive Kalman filters for underwater vehicle dead reckoning

    Science.gov (United States)

    Xiao, Kun; Fang, Shao-Ji; Pang, Yong-Jie

    2007-06-01

    To impove underwater vehicle dead reckoning, a developed strong tracking adaptive kalman filter is proposed. The filter is improved with an additional adaptive factor and an estimator of measurement noise covariance. Since the magnitude of fading factor is changed adaptively, the tracking ability of the filter is still enhanced in low velocity condition of underwater vehicles. The results of simulation tests prove the presented filter effective.

  17. Underwater striling engine design with modified one-dimensional model

    OpenAIRE

    Li, Daijin; Qin, Kan; Luo, Kai

    2015-01-01

    Stirling engines are regarded as an efficient and promising power system for underwater devices. Currently, many researches on one-dimensional model is used to evaluate thermodynamic performance of Stirling engine, but in which there are still some aspects which cannot be modeled with proper mathematical models such as mechanical loss or auxiliary power. In this paper, a four-cylinder double-acting Stirling engine for Unmanned Underwater Vehicles (UUVs) is discussed. And a one-dimensional mod...

  18. Terminal homing position estimation forAutonomous underwater vehicle docking

    Science.gov (United States)

    2017-06-01

    79  ix LIST OF FIGURES Figure 1.  NPS REMUS 100 with WHOI Docking Station. Source: [1...underwater missions were short and quick . Now, with advanced technology, underwater missions can be as long as the user desires. The new AUVs have...the full information problem. In order to use the MHE approach for real-time applications, the optimization process should be quick and accurate

  19. A potential flow based flight simulator for an underwater glider

    OpenAIRE

    Phoemsapthawee, Surasak; Le Boulluec, Marc; Laurens, Jean-marc; Deniset, Francois

    2013-01-01

    Underwater gliders are recent innovative types of autonomous underwater vehicles (AUVs) used in ocean exploration and observation. They adjust their buoyancy to dive and to return to the ocean surface. During the change of altitude, they use the hydrodynamic forces developed by their wings to move forward. Their flights are controlled by changing the position of their centers of gravity and their buoyancy to adjust their trim and heel angles. For better flight control, the understanding of th...

  20. Analytical and Numerical Optimal Motion Planning for an Underwater Glider

    OpenAIRE

    Kraus, Robert J.

    2010-01-01

    The use of autonomous underwater vehicles (AUVs) for oceanic observation and research is becoming more common. Underwater gliders are a specific class of AUV that do not use conventional propulsion. Instead they change their buoyancy and center of mass location to control attitude and trajectory. The vehicles spend most of their time in long, steady glides, so even minor improvements in glide range can be magnified over multiple dives. This dissertation presents a rigid-body dynamic system...

  1. Boundary curvature effects on gas bubble oscillations in underwater explosion

    OpenAIRE

    Matsumoto, Kazuhiro

    1996-01-01

    The oscillation of a gas bubble produced as a result of underwater explosion could cause the severe whipping damage on nearby marine vehicle. The effects of rigid boundary curvatures to explosive gas bubble oscillation behavior in underwater were investigated. The analyses were conducted using a multimaterial Lagrangian-Eulerian finite element code, MSC/DYTRAN. The incident shock wave pressure, bubble pulse pressure, gas bubble radius and period were calculated for the case of detonation of a...

  2. Deep Learning Methods for Underwater Target Feature Extraction and Recognition

    Directory of Open Access Journals (Sweden)

    Gang Hu

    2018-01-01

    Full Text Available The classification and recognition technology of underwater acoustic signal were always an important research content in the field of underwater acoustic signal processing. Currently, wavelet transform, Hilbert-Huang transform, and Mel frequency cepstral coefficients are used as a method of underwater acoustic signal feature extraction. In this paper, a method for feature extraction and identification of underwater noise data based on CNN and ELM is proposed. An automatic feature extraction method of underwater acoustic signals is proposed using depth convolution network. An underwater target recognition classifier is based on extreme learning machine. Although convolution neural networks can execute both feature extraction and classification, their function mainly relies on a full connection layer, which is trained by gradient descent-based; the generalization ability is limited and suboptimal, so an extreme learning machine (ELM was used in classification stage. Firstly, CNN learns deep and robust features, followed by the removing of the fully connected layers. Then ELM fed with the CNN features is used as the classifier to conduct an excellent classification. Experiments on the actual data set of civil ships obtained 93.04% recognition rate; compared to the traditional Mel frequency cepstral coefficients and Hilbert-Huang feature, recognition rate greatly improved.

  3. Optimal Node Placement in Underwater Acoustic Sensor Network

    KAUST Repository

    Felemban, Muhamad

    2011-10-01

    Almost 70% of planet Earth is covered by water. A large percentage of underwater environment is unexplored. In the past two decades, there has been an increase in the interest of exploring and monitoring underwater life among scientists and in industry. Underwater operations are extremely difficult due to the lack of cheap and efficient means. Recently, Wireless Sensor Networks have been introduced in underwater environment applications. However, underwater communication via acoustic waves is subject to several performance limitations, which makes the relevant research issues very different from those on land. In this thesis, we investigate node placement for building an initial Underwater Wireless Sensor Network infrastructure. Firstly, we formulated the problem into a nonlinear mathematic program with objectives of minimizing the total transmission loss under a given number of sensor nodes and targeted volume. We conducted experiments to verify the proposed formulation, which is solved using Matlab optimization tool. We represented each node with a truncated octahedron to fill out the 3D space. The truncated octahedrons are tiled in the 3D space with each node in the center where locations of the nodes are given using 3D coordinates. Results are supported using ns-3 simulator. Results from simulation are consistent with the obtained results from mathematical model with less than 10% error.

  4. Performance Evaluation of Hybrid Acoustic-Optical Underwater Swarm Networks

    Directory of Open Access Journals (Sweden)

    Samuela PERSIA

    2016-04-01

    Full Text Available The Underwater Swarm is a particular Underwater Network configuration characterized by nodes very close one to each other, with mobility capability. The structure of the network is that of a distributed network, in which the nodes, through the exchange of control information, will take decisions in collaborative manner. This type of network raises challenges for its effective design and development, for which the only use of acoustic communication as traditionally suggested in underwater communication could be not enough. A new emerging solution could be a hybrid solution that combines the use of acoustic and optical channel in order to overcome the acoustic channel limitations in underwater environment. In this work, we want to investigate how the acoustic and optical communications influence the Underwater Swarm performance by considering the Low Layers Protocols (Physical Layer, Data Link Layer and Network Layer effects over the two different propagation technologies. Performance simulations have been carried out to suggest how the new hybrid system could be designed. This study will permit to provide useful analysis for the real implementation of an Underwater Swarm based on hybrid communication technology.

  5. The sounds of nanotechnology

    Science.gov (United States)

    Campbell, Norah; Deane, Cormac; Murphy, Padraig

    2017-07-01

    Public perceptions of nanotechnology are shaped by sound in surprising ways. Our analysis of the audiovisual techniques employed by nanotechnology stakeholders shows that well-chosen sounds can help to win public trust, create value and convey the weird reality of objects on the nanoscale.

  6. Poetry Pages. Sound Effects.

    Science.gov (United States)

    Fina, Allan de

    1992-01-01

    Explains how elementary teachers can help students understand onomatopoeia, suggesting that they define onomatopoeia, share examples of it, read poems and have students discuss onomatopoeic words, act out common household sounds, write about sound effects, and create choral readings of onomatopoeic poems. Two appropriate poems are included. (SM)

  7. Sound propagation in cities

    NARCIS (Netherlands)

    Salomons, E.; Polinder, H.; Lohman, W.; Zhou, H.; Borst, H.

    2009-01-01

    A new engineering model for sound propagation in cities is presented. The model is based on numerical and experimental studies of sound propagation between street canyons. Multiple reflections in the source canyon and the receiver canyon are taken into account in an efficient way, while weak

  8. OMNIDIRECTIONAL SOUND SOURCE

    DEFF Research Database (Denmark)

    1996-01-01

    A sound source comprising a loudspeaker (6) and a hollow coupler (4) with an open inlet which communicates with and is closed by the loudspeaker (6) and an open outlet, said coupler (4) comprising rigid walls which cannot respond to the sound pressures produced by the loudspeaker (6). According...

  9. Breaking the Sound Barrier

    Science.gov (United States)

    Brown, Tom; Boehringer, Kim

    2007-01-01

    Students in a fourth-grade class participated in a series of dynamic sound learning centers followed by a dramatic capstone event--an exploration of the amazing Trashcan Whoosh Waves. It's a notoriously difficult subject to teach, but this hands-on, exploratory approach ignited student interest in sound, promoted language acquisition, and built…

  10. Notes on Sound

    Directory of Open Access Journals (Sweden)

    Bonnie Jones

    2012-08-01

    Full Text Available Bonnie Jones creates improvised and composed text-sound performances that explore the fluidity and function of electronic noise (field recordings, circuit bending and text (poetry, found, spoken. She is interested in how people perceive, “read” and interact with these sounds and texts given our current technological moment.

  11. Waveform analysis of sound

    CERN Document Server

    Tohyama, Mikio

    2015-01-01

    What is this sound? What does that sound indicate? These are two questions frequently heard in daily conversation. Sound results from the vibrations of elastic media and in daily life provides informative signals of events happening in the surrounding environment. In interpreting auditory sensations, the human ear seems particularly good at extracting the signal signatures from sound waves. Although exploring auditory processing schemes may be beyond our capabilities, source signature analysis is a very attractive area in which signal-processing schemes can be developed using mathematical expressions. This book is inspired by such processing schemes and is oriented to signature analysis of waveforms. Most of the examples in the book are taken from data of sound and vibrations; however, the methods and theories are mostly formulated using mathematical expressions rather than by acoustical interpretation. This book might therefore be attractive and informative for scientists, engineers, researchers, and graduat...

  12. InfoSound

    DEFF Research Database (Denmark)

    Sonnenwald, Diane H.; Gopinath, B.; Haberman, Gary O.

    1990-01-01

    The authors explore ways to enhance users' comprehension of complex applications using music and sound effects to present application-program events that are difficult to detect visually. A prototype system, Infosound, allows developers to create and store musical sequences and sound effects...... with application events, and have real-time, continuous auditory control of sounds during application execution. InfoSound has been used to create auditory interfaces for two applications: a telephone network service simulation and a parallel computation simulation. The auditory interfaces in these applications...... helped users detect rapid, multiple-event sequences that were difficult to visually detect using text and graphical interfaces. The authors describe the architecture of InfoSound, the use of the system, and the lessons learned....

  13. Sound classification of dwellings

    DEFF Research Database (Denmark)

    Rasmussen, Birgit

    2012-01-01

    National schemes for sound classification of dwellings exist in more than ten countries in Europe, typically published as national standards. The schemes define quality classes reflecting different levels of acoustical comfort. Main criteria concern airborne and impact sound insulation between...... dwellings, facade sound insulation and installation noise. The schemes have been developed, implemented and revised gradually since the early 1990s. However, due to lack of coordination between countries, there are significant discrepancies, and new standards and revisions continue to increase the diversity...... is needed, and a European COST Action TU0901 "Integrating and Harmonizing Sound Insulation Aspects in Sustainable Urban Housing Constructions", has been established and runs 2009-2013, one of the main objectives being to prepare a proposal for a European sound classification scheme with a number of quality...

  14. The influence of sea ice, wind speed and marine mammals on Southern Ocean ambient sound

    Science.gov (United States)

    Menze, Sebastian; Zitterbart, Daniel P.; van Opzeeland, Ilse; Boebel, Olaf

    2017-01-01

    This paper describes the natural variability of ambient sound in the Southern Ocean, an acoustically pristine marine mammal habitat. Over a 3-year period, two autonomous recorders were moored along the Greenwich meridian to collect underwater passive acoustic data. Ambient sound levels were strongly affected by the annual variation of the sea-ice cover, which decouples local wind speed and sound levels during austral winter. With increasing sea-ice concentration, area and thickness, sound levels decreased while the contribution of distant sources increased. Marine mammal sounds formed a substantial part of the overall acoustic environment, comprising calls produced by Antarctic blue whales (Balaenoptera musculus intermedia), fin whales (Balaenoptera physalus), Antarctic minke whales (Balaenoptera bonaerensis) and leopard seals (Hydrurga leptonyx). The combined sound energy of a group or population vocalizing during extended periods contributed species-specific peaks to the ambient sound spectra. The temporal and spatial variation in the contribution of marine mammals to ambient sound suggests annual patterns in migration and behaviour. The Antarctic blue and fin whale contributions were loudest in austral autumn, whereas the Antarctic minke whale contribution was loudest during austral winter and repeatedly showed a diel pattern that coincided with the diel vertical migration of zooplankton.

  15. Evaluation of a Single-Beam Sonar System to Map Seagrass at Two Sites in Northern Puget Sound, Washington

    Science.gov (United States)

    Stevens, Andrew W.; Lacy, Jessica R.; Finlayson, David P.; Gelfenbaum, Guy

    2008-01-01

    Seagrass at two sites in northern Puget Sound, Possession Point and nearby Browns Bay, was mapped using both a single-beam sonar and underwater video camera. The acoustic and underwater video data were compared to evaluate the accuracy of acoustic estimates of seagrass cover. The accuracy of the acoustic method was calculated for three classifications of seagrass observed in underwater video: bare (no seagrass), patchy seagrass, and continuous seagrass. Acoustic and underwater video methods agreed in 92 percent and 74 percent of observations made in bare and continuous areas, respectively. However, in patchy seagrass, the agreement between acoustic and underwater video was poor (43 percent). The poor agreement between the two methods in areas with patchy seagrass is likely because the two instruments were not precisely colocated. The distribution of seagrass at the two sites differed both in overall percent vegetated and in the distribution of percent cover versus depth. On the basis of acoustic data, seagrass inhabited 0.29 km2 (19 percent of total area) at Possession Point and 0.043 km2 (5 percent of total area) at the Browns Bay study site. The depth distribution at the two sites was markedly different. Whereas the majority of seagrass at Possession Point occurred between -0.5 and -1.5 m MLLW, most seagrass at Browns Bay occurred at a greater depth, between -2.25 and -3.5 m MLLW. Further investigation of the anthropogenic and natural factors causing these differences in distribution is needed.

  16. Improvement of the sound transmission loss of panels by means of acoustically tuned resonators

    NARCIS (Netherlands)

    Hannink, M.H.C.; Grant, I

    2006-01-01

    When a panel is excited, either structurally or acoustically, sound is radiated from the panel. Previous research by the author has shown that tuned acoustic tube resonators can be used to reduce the radiated sound. A one-dimensional analytical model model was validated by experiments in an

  17. Extending The Calibration In The Underwater Sound Reference Division (USRD) Reciprocity Coupler To Incorporate Phase

    Science.gov (United States)

    2016-09-01

    have a much higher impedance than the acoustic medium. 3. No air or any other low impedance material can be present in the coupler. The hydrophone...pressure ram controls the hydrostatic pressure in the coupler fluid, castor oil. Chamber temperature is controlled by heating or cooling distilled water...differential amplifier 4 USRD H48 Reciprocity Coupler 5 Ithaco 1201 6 NI BMC-2110 and NI-6259 7 Laptop Computer with Matlab 8 Pressure Ram 9 Neslab Endocal

  18. Acoustic Observatory Provides Real-Time Underwater Sounds from the Antarctic Ocean

    OpenAIRE

    Boebel, Olaf; Kindermann, Lars; Klinck, Holger; Bornemann, Horst; Plötz, Joachim; Steinhage, Daniel; Riedel, Sven; Burkhardt, Elke

    2006-01-01

    To obtain real-time, year-round acoustic data from the coastal Antarctic Ocean, an autonomous listening station, PALAOA (PerenniAL Acoustic Observatory in the Antarctic Ocean, or Hawaiian whale), was constructed in austral summer 2005/06, 15 km North of the German Neumayer Base. PALAOAs design was guided by demanding prerequisites: perennial, 365/24, autonomous operation, real-time data access, and full frequency and dynamic coverage. The station is located at 70°31S 8°13W, on the Ekström ice...

  19. Effects of Environmental Variability on Long-Range Underwater Sound Propagation: Mode Processing of LOAPEX

    Science.gov (United States)

    2011-05-01

    the ocean has been developed (together with T. Duda). Large changes in upper- ocean absorption coefficient predicted to follow carbon dioxide uptake...existing theory to the environments with strong range dependence. In addition, a study of oceanic acoustic response to acidification has been made...implementation. The second paper is a study of ambient noise level change in the ocean due to acidification . Also two papers devoted to the modal analysis

  20. Turbidity, SOLAR RADIATION - ATMOSPHERIC and other data from UNKNOWN and STIRNI in the Long Island Sound from 1952-01-21 to 1971-06-06 (NODC Accession 9000041)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains two files of salinity/temperature/oxygen data from Long Island Sound data submitted by J.C. Ayers from Cornell University and Davids Island...

  1. Turbidity, SOLAR RADIATION - ATMOSPHERIC and other data from UNKNOWN in the New York Bight and Long Island Sound from 1972-08-01 to 1973-09-20 (NODC Accession 9000039)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This accession consists of nutrient data from Long Island Sound provided by Mr. Robert N. Reid from NOAA/NMFS Sandy Hook Laboratory. The data were collected from...

  2. Autonomous Underwater Vehicle Magnetic Mapping System

    Science.gov (United States)

    Steigerwalt, R.; Johnson, R. M.; Trembanis, A. C.; Schmidt, V. E.; Tait, G.

    2012-12-01

    An Autonomous Underwater Vehicle (AUV) Magnetic Mapping (MM) System has been developed and tested for military munitions detection as well as pipeline locating, wreck searches, and geologic surveys in underwater environments. The system is comprised of a high sensitivity Geometrics G-880AUV cesium vapor magnetometer integrated with a Teledyne-Gavia AUV and associated Doppler enabled inertial navigation further utilizing traditional acoustic bathymetric and side scan imaging. All onboard sensors and associated electronics are managed through customized crew members to autonomously operate through the vehicles primary control module. Total field magnetic measurements are recorded with asynchronous time-stamped data logs which include position, altitude, heading, pitch, roll, and electrical current usage. Pre-planned mission information can be uploaded to the system operators to define data collection metrics including speed, height above seafloor, and lane or transect spacing specifically designed to meet data quality objectives for the survey. As a result of the AUVs modular design, autonomous navigation and rapid deployment capabilities, the AUV MM System provides cost savings over current surface vessel surveys by reducing the mobilization/demobilization effort, thus requiring less manpower for operation and reducing or eliminating the need for a surface support vessel altogether. When the system completes its mission, data can be remotely downloaded via W-LAN and exported for use in advanced signal processing platforms. Magnetic compensation software has been concurrently developed to accept electrical current measurements directly from the AUV to address distortions from permanent and induced magnetization effects on the magnetometer. Maneuver and electrical current compensation terms can be extracted from the magnetic survey missions to perform automated post-process corrections. Considerable suppression of system noise has been observed over traditional

  3. Underwater Animal Monitoring Magnetic Sensor System

    KAUST Repository

    Kaidarova, Altynay

    2017-10-01

    Obtaining new insights into the behavior of free-living marine organisms is fundamental for conservation efforts and anticipating the impact of climate change on marine ecosystems. Despite the recent advances in biotelemetry, collecting physiological and behavioral parameters of underwater free-living animals remains technically challenging. In this thesis, we develop the first magnetic underwater animal monitoring system that utilizes Tunnel magnetoresistance (TMR) sensors, the most sensitive solid-state sensors today, coupled with flexible magnetic composites. The TMR sensors are composed of CoFeB free layers and MgO tunnel barriers, patterned using standard optical lithography and ion milling procedures. The short and long-term stability of the TMR sensors has been studied using statistical and Allan deviation analysis. Instrumentation noise has been reduced using optimized electrical interconnection schemes. We also develop flexible NdFeB-PDMS composite magnets optimized for applications in corrosive marine environments, and which can be attached to marine animals. The magnetic and mechanical properties are studied for different NdFeB powder concentrations and the performance of the magnetic composites for different exposure times to sea water is systematically investigated. Without protective layer, the composite magnets loose more than 50% of their magnetization after 51 days in seawater. The durability of the composite magnets can be considerably improved by using polymer coatings which are protecting the composite magnet, whereby Parylene C is found to be the most effective solution, providing simultaneously corrosion resistance, flexibility, and enhanced biocompatibility. A Parylene C film of 2μm thickness provides the sufficient protection of the magnetic composite in corrosive aqueous environments for more than 70 days. For the high level performance of the system, the theoretically optimal position of the composite magnets with respect to the sensing

  4. Digitizing a sound archive

    DEFF Research Database (Denmark)

    Cone, Louise

    2017-01-01

    In 1990 an artist by the name of William Louis Sørensen was hired by the National Gallery of Denmark to collect important works of art – made from sound. His job was to acquire sound art, but also recordings that captured rare artistic occurrences, music, performances and happenings from both...... Danish and international artists. His methodology left us with a large collection of unique and inspirational time-based media sound artworks that have, until very recently, been inaccessible. Existing on an array of different media formats, such as open reel tapes, 8-track and 4 track cassettes, VHS...

  5. Prediction of Tonal Underwater Noise Pattern from Cavitating Propellers with Special Attention to Ice Cover Effects

    Directory of Open Access Journals (Sweden)

    Streckwall Heinrich

    2015-01-01

    Full Text Available To predict underwater noise spectra associated to regular occurrence of propeller cavitation we have extended an existing method [1] (used for the prediction of fluctuating hull pressures to become applicable for effects that are linked to a finite speed of sound. In [2] an intermediate approach was realized where (besides the hull far field boundaries were introduced but the incompressible flow assumption was kept. However compressibility effects become noticeable in the far field, which may be judged to start at some 2-3 propeller-diameters distance from the centre of the cavitation events, if we confine to emissions at 1st-4th blade frequency. It was a logical continuation of our former efforts to realize a compressible flow model and integrate the propeller as a noise source. Having increased the functionality of our approach by referencing the speed of sound, the precision of the method was also somehow reduced. In our former approach, like in comparable approaches (see for instance [3] and [4], the singularity system generating the near field propeller induced pressures involved various sources and vortices distributed on the propeller blades. With our current compressible approach this complexity was dropped, as a single point source substitutes the cavitating propeller. Such a simplification correlates with the assumption, that the monopole character of a noise source is decisive for the far field noise levels. In this contribution we outline the steps characterizing the procedure for predicting tonal underwater noise from cavitating propellers. In the first step a Vortex Lattice Method (VLM is used to access the cavitation pattern on the propeller with special focus on the cavity volume attached to one blade. The second step accumulates the distributed cavities to establish a fluctuating point source of equivalent far field noise characteristic. As relevant limits the hull, the free surface, the sea bottom and an ice cover are

  6. Into the sounding environment A compositional approach

    OpenAIRE

    Tzedaki, Aikaterini

    2012-01-01

    The focus of the compositional approach presented in this folio is the sounding environment. The term sounding environment is used in this context to refer to the whole of our living experience in the world which we might register as relating to sound. It might include everything that is sounding, seemingly sounding, imagined sounding, remembered sounding, sensed as sounding, composed to sound. It includes thus the actual sound environment, all that is sensed or interpreted as sound and imagi...

  7. Inside-in, alternative paradigms for sound spatialization

    Science.gov (United States)

    Bahn, Curtis; Moore, Stephan

    2003-04-01

    Arrays of widely spaced mono-directional loudspeakers (P.A.-style stereo configurations or ``outside-in'' surround-sound systems) have long provided the dominant paradigms for electronic sound diffusion. So prevalent are these models that alternatives have largely been ignored and electronic sound, regardless of musical aesthetic, has come to be inseparably associated with single-channel speakers, or headphones. We recognize the value of these familiar paradigms, but believe that electronic sound can and should have many alternative, idiosyncratic voices. Through the design and construction of unique sound diffusion structures, one can reinvent the nature of electronic sound; when allied with new sensor technologies, these structures offer alternative modes of interaction with techniques of sonic computation. This paper describes several recent applications of spherical speakers (multichannel, outward-radiating geodesic speaker arrays) and Sensor-Speaker-Arrays (SenSAs: combinations of various sensor devices with outward-radiating multi-channel speaker arrays). This presentation introduces the development of four generations of spherical speakers-over a hundred individual speakers of various configurations-and their use in many different musical situations including live performance, recording, and sound installation. We describe the design and construction of these systems, and, more generally, the new ``voices'' they give to electronic sound.

  8. A Framework for Evaluating Advanced Search Concepts for Multiple Autonomous Underwater Vehicle (AUV) Mine Countermeasures (MCM)

    National Research Council Canada - National Science Library

    Gooding, Trent

    2001-01-01

    .... In recent years, autonomous underwater vehicles (AUV) have emerged as a viable technology for conducting underwater search, survey, and clearance operations in support of the mine countermeasures (MCM) mission...

  9. A comparative view of routing protocols for underwater wireless sensor networks

    NARCIS (Netherlands)

    Bayrakdar, Y.; Meratnia, Nirvana; Kantarci, Aylin

    2011-01-01

    Design of efficient routing protocols for underwater sensor networks is challenging because of the distinctive characteristics of the water medium. Currently, many routing protocols are available for terrestrial wireless sensor networks. However, specific properties of underwater medium such as

  10. US-Japan Cooperative Research on Biology-Inspired Precision Maneuvering of Underwater Vehicles

    National Research Council Canada - National Science Library

    Kato, Naomi

    2004-01-01

    .... We constructed an underwater vehicle equipped with two pairs of mechanical pectoral fins and pectoral fin controllers to examine the swimming performance of the underwater vehicle in still water...

  11. Predictive Model for the Analysis of the Effects of Underwater Impulsive Sources on Marine Life

    National Research Council Canada - National Science Library

    Lazauski, Colin J

    2007-01-01

    A method is provided to predict the biological consequences to marine animals from exposure to multiple underwater impulsive sources by simulating underwater explosions over a defined period of time...

  12. Urban Sound Ecologies

    DEFF Research Database (Denmark)

    Groth, Sanne Krogh; Samson, Kristine

    2013-01-01

    . The article concludes that the ways in which recent sound installations work with urban ecologies vary. While two of the examples blend into the urban environment, the other transfers the concert format and its mode of listening to urban space. Last, and in accordance with recent soundscape research, we point...... share the characteristics of site specificity. However, this article will consider the artwork in a broader context by re-examining how sound installations relate to the urban environment. For that purpose, this article brings together ecology terms from acoustic ecology of the sound theories...... to how artists working with new information and media technologies create inventive ways of inserting sound and image into urban environments....

  13. The sound of activism.

    Science.gov (United States)

    Sandstrom, B; Vetter, C

    2001-01-01

    ABSTRACT A longtime advocate for female empowerment and equality, Boden Sandstrom has worked for political change in many arenas. In the 1960s, she began a career as a librarian, but soon made activism her full-time job, working for feminist, leftist and socialist causes. In the 1970s, she found a way to turn her lifelong passion for music into a career as a sound engineer. Once established in that profession, she began donating her services to political events, marches, demonstrations, and rallies. After thirteen years of running her own company, called Woman Sound,Inc. (later City Sound Productions,Inc.), she turned to the study of ethnomusicology. She is now Program Manager and Lecturer for the Ethnomusicology Program at the University of Maryland, where she is also working on her doctorate in that subject. She continues to freelance as a sound engineer and serve as a technical producer for major events.

  14. Sound as Popular Culture

    DEFF Research Database (Denmark)

    , physical, perceptual, and sensory processes that integrate a multitude of cultural traditions and forms of knowledge. The chapters discuss conceptual issues as well as terminologies and research methods; analyze historical and contemporary case studies of listening in various sound cultures; and consider......The wide-ranging texts in this book take as their premise the idea that sound is a subject through which popular culture can be analyzed in an innovative way. From an infant’s gurgles over a baby monitor to the roar of the crowd in a stadium to the sub-bass frequencies produced by sound systems...... in the disco era, sound—not necessarily aestheticized as music—is inextricably part of the many domains of popular culture. Expanding the view taken by many scholars of cultural studies, the contributors consider cultural practices concerning sound not merely as semiotic or signifying processes but as material...

  15. Sound as Popular Culture

    DEFF Research Database (Denmark)

    The wide-ranging texts in this book take as their premise the idea that sound is a subject through which popular culture can be analyzed in an innovative way. From an infant’s gurgles over a baby monitor to the roar of the crowd in a stadium to the sub-bass frequencies produced by sound systems...... in the disco era, sound—not necessarily aestheticized as music—is inextricably part of the many domains of popular culture. Expanding the view taken by many scholars of cultural studies, the contributors consider cultural practices concerning sound not merely as semiotic or signifying processes but as material......, physical, perceptual, and sensory processes that integrate a multitude of cultural traditions and forms of knowledge. The chapters discuss conceptual issues as well as terminologies and research methods; analyze historical and contemporary case studies of listening in various sound cultures; and consider...

  16. Sounds of Web Advertising

    DEFF Research Database (Denmark)

    Jessen, Iben Bredahl; Graakjær, Nicolai Jørgensgaard

    2010-01-01

    Sound seems to be a neglected issue in the study of web ads. Web advertising is predominantly regarded as visual phenomena–commercial messages, as for instance banner ads that we watch, read, and eventually click on–but only rarely as something that we listen to. The present chapter presents...... an overview of the auditory dimensions in web advertising: Which kinds of sounds do we hear in web ads? What are the conditions and functions of sound in web ads? Moreover, the chapter proposes a theoretical framework in order to analyse the communicative functions of sound in web advertising. The main...... argument is that an understanding of the auditory dimensions in web advertising must include a reflection on the hypertextual settings of the web ad as well as a perspective on how users engage with web content....

  17. It sounds good!

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Both the atmosphere and we ourselves are hit by hundreds of particles every second and yet nobody has ever heard a sound coming from these processes. Like cosmic rays, particles interacting inside the detectors at the LHC do not make any noise…unless you've decided to use the ‘sonification’ technique, in which case you might even hear the Higgs boson sound like music. Screenshot of the first page of the "LHC sound" site. A group of particle physicists, composers, software developers and artists recently got involved in the ‘LHC sound’ project to make the particles at the LHC produce music. Yes…music! The ‘sonification’ technique converts data into sound. “In this way, if you implement the right software you can get really nice music out of the particle tracks”, says Lily Asquith, a member of the ATLAS collaboration and one of the initiators of the project. The ‘LHC...

  18. Sound Visualization and Holography

    Science.gov (United States)

    Kock, Winston E.

    1975-01-01

    Describes liquid surface holograms including their application to medicine. Discusses interference and diffraction phenomena using sound wave scanning techniques. Compares focussing by zone plate to holographic image development. (GH)

  19. Shape optimisation of an underwater Bernoulli gripper

    Science.gov (United States)

    Flint, Tim; Sellier, Mathieu

    2015-11-01

    In this work, we are interested in maximising the suction produced by an underwater Bernoulli gripper. Bernoulli grippers work by exploiting low pressure regions caused by the acceleration of a working fluid through a narrow channel, between the gripper and a surface, to provide a suction force. This mechanism allows for non-contact adhesion to various surfaces and may be used to hold a robot to the hull of a ship while it inspects welds for example. A Bernoulli type pressure analysis was used to model the system with a Darcy friction factor approximation to include the effects of frictional losses. The analysis involved a constrained optimisation in order to avoid cavitation within the mechanism which would result in decreased performance and damage to surfaces. A sensitivity based method and gradient descent approach was used to find the optimum shape of a discretised surface. The model's accuracy has been quantified against finite volume computational fluid dynamics simulation (ANSYS CFX) using the k- ω SST turbulence model. Preliminary results indicate significant improvement in suction force when compared to a simple geometry by retaining a pressure just above that at which cavitation would occur over as much surface area as possible. Doctoral candidate in the Mechanical Engineering Department of the University of Canterbury, New Zealand.

  20. The Modular Optical Underwater Survey System

    Directory of Open Access Journals (Sweden)

    Ruhul Amin

    2017-10-01

    Full Text Available The Pacific Islands Fisheries Science Center deploys the Modular Optical Underwater Survey System (MOUSS to estimate the species-specific, size-structured abundance of commercially-important fish species in Hawaii and the Pacific Islands. The MOUSS is an autonomous stereo-video camera system designed for the in situ visual sampling of fish assemblages. This system is rated to 500 m and its low-light, stereo-video cameras enable identification, counting, and sizing of individuals at a range of 0.5–10 m. The modular nature of MOUSS allows for the efficient and cost-effective use of various imaging sensors, power systems, and deployment platforms. The MOUSS is in use for surveys in Hawaii, the Gulf of Mexico, and Southern California. In Hawaiian waters, the system can effectively identify individuals to a depth of 250 m using only ambient light. In this paper, we describe the MOUSS’s application in fisheries research, including the design, calibration, analysis techniques, and deployment mechanism.