WorldWideScience

Sample records for acoustic location system

  1. An FBG acoustic emission source locating system based on PHAT and GA

    Science.gov (United States)

    Shen, Jing-shi; Zeng, Xiao-dong; Li, Wei; Jiang, Ming-shun

    2017-09-01

    Using the acoustic emission locating technology to monitor the health of the structure is important for ensuring the continuous and healthy operation of the complex engineering structures and large mechanical equipment. In this paper, four fiber Bragg grating (FBG) sensors are used to establish the sensor array to locate the acoustic emission source. Firstly, the nonlinear locating equations are established based on the principle of acoustic emission, and the solution of these equations is transformed into an optimization problem. Secondly, time difference extraction algorithm based on the phase transform (PHAT) weighted generalized cross correlation provides the necessary conditions for the accurate localization. Finally, the genetic algorithm (GA) is used to solve the optimization model. In this paper, twenty points are tested in the marble plate surface, and the results show that the absolute locating error is within the range of 10 mm, which proves the accuracy of this locating method.

  2. Acoustic building infiltration measurement system

    Science.gov (United States)

    Muehleisen, Ralph T.; Raman, Ganesh

    2018-04-10

    Systems and methods of detecting and identifying a leak from a container or building. Acoustic pressure and velocity are measured. Acoustic properties are acquired from the measured values. The acoustic properties are converted to infiltration/leakage information. Nearfield Acoustic Holography (NAH) may be one method to detect the leakages from a container by locating the noise sources.

  3. Ambiguity of source location in acoustic emission technique

    International Nuclear Information System (INIS)

    Barat, P.; Mukherjee, P.; Kalyanasundaram, P.; Raj, B.

    1996-01-01

    Location of acoustic emission (AE) source in a plane is detected from the difference of the arrival times of the AE signal to at least three sensors placed on it. The detected location may not be unique in all cases. In this paper, the condition for the unambiguous solution for the location of the source has been deduced mathematically in terms of arrival times of the AE signal, the coordinate of the three sensors and the acoustic velocity. (author)

  4. Acoustic emission non-destructive testing of structures using source location techniques.

    Energy Technology Data Exchange (ETDEWEB)

    Beattie, Alan G.

    2013-09-01

    The technology of acoustic emission (AE) testing has been advanced and used at Sandia for the past 40 years. AE has been used on structures including pressure vessels, fire bottles, wind turbines, gas wells, nuclear weapons, and solar collectors. This monograph begins with background topics in acoustics and instrumentation and then focuses on current acoustic emission technology. It covers the overall design and system setups for a test, with a wind turbine blade as the object. Test analysis is discussed with an emphasis on source location. Three test examples are presented, two on experimental wind turbine blades and one on aircraft fire extinguisher bottles. Finally, the code for a FORTRAN source location program is given as an example of a working analysis program. Throughout the document, the stress is on actual testing of real structures, not on laboratory experiments.

  5. A New Fault Location Approach for Acoustic Emission Techniques in Wind Turbines

    Directory of Open Access Journals (Sweden)

    Carlos Quiterio Gómez Muñoz

    2016-01-01

    Full Text Available The renewable energy industry is undergoing continuous improvement and development worldwide, wind energy being one of the most relevant renewable energies. This industry requires high levels of reliability, availability, maintainability and safety (RAMS for wind turbines. The blades are critical components in wind turbines. The objective of this research work is focused on the fault detection and diagnosis (FDD of the wind turbine blades. The FDD approach is composed of a robust condition monitoring system (CMS and a novel signal processing method. CMS collects and analyses the data from different non-destructive tests based on acoustic emission. The acoustic emission signals are collected applying macro-fiber composite (MFC sensors to detect and locate cracks on the surface of the blades. Three MFC sensors are set in a section of a wind turbine blade. The acoustic emission signals are generated by breaking a pencil lead in the blade surface. This method is used to simulate the acoustic emission due to a breakdown of the composite fibers. The breakdown generates a set of mechanical waves that are collected by the MFC sensors. A graphical method is employed to obtain a system of non-linear equations that will be used for locating the emission source. This work demonstrates that a fiber breakage in the wind turbine blade can be detected and located by using only three low cost sensors. It allows the detection of potential failures at an early stages, and it can also reduce corrective maintenance tasks and downtimes and increase the RAMS of the wind turbine.

  6. ACOUSTIC DETECTING AND LOCATING GAS PIPE LINE INFRINGEMENT

    Energy Technology Data Exchange (ETDEWEB)

    John L. Loth; Gary J. Morris; George M. Palmer; Richard Guiler; Patrick Browning

    2004-10-31

    The extensive network of high-pressure natural gas transmission pipelines covering the United States provides an important infrastructure for our energy independence. Early detection of pipeline leaks and infringements by construction equipment, resulting in corrosion fractures, presents an important aspect of our national security policy. The National Energy Technology Laboratory Strategic Center for Natural Gas (SCVG) is and has been funding research on various applicable techniques. The WVU research team has focused on monitoring pipeline background acoustic signals generated and transmitted by gas flowing through the gas inside the pipeline. In case of a pipeline infringement, any mechanical impact on the pipe wall, or escape of high-pressure gas, generates acoustic signals traveling both up and down stream through the gas. Sudden changes in flow noise are detectable with a Portable Acoustic Monitoring Package (PAMP), developed under this contract. It incorporates a pressure compensating microphone and a signal- recording device. Direct access to the gas inside the line is obtained by mounting such a PAMP, with a 1/2 inch NPT connection, to a pipeline pressure port found near most shut-off valves. An FFT of the recorded signal subtracted by that of the background noise recorded one-second earlier appears to sufficiently isolate the infringement signal to allow source interpretation. Using cell phones for data downloading might allow a network of such 1000-psi rated PAMP's to acoustically monitor a pipeline system and be trained by neural network software to positively identify and locate any pipeline infringement.

  7. ACOUSTIC DETECTING AND LOCATING GAS PIPE LINE INFRINGEMENT

    Energy Technology Data Exchange (ETDEWEB)

    John L. Loth; Gary J. Morris; George M. Palmer; Richard Guiler; Patrick Browning

    2004-12-01

    The extensive network of high-pressure natural gas transmission pipelines covering the United States provides an important infrastructure for our energy independence. Early detection of pipeline leaks and infringements by construction equipment, resulting in corrosion fractures, presents an important aspect of our national security policy. The National Energy Technology Laboratory Strategic Center for Natural Gas (SCVG) is and has been funding research on various applicable techniques. The WVU research team has focused on monitoring pipeline background acoustic signals generated and transmitted by gas flowing through the gas inside the pipeline. In case of a pipeline infringement, any mechanical impact on the pipe wall, or escape of high-pressure gas, generates acoustic signals traveling both up and down stream through the gas. Sudden changes in flow noise are detectable with a Portable Acoustic Monitoring Package (PAMP), developed under this contract. It incorporates a pressure compensating microphone and a signal- recording device. Direct access to the gas inside the line is obtained by mounting such a PAMP, with a 1/2 inch NPT connection, to a pipeline pressure port found near most shut-off valves. An FFT of the recorded signal subtracted by that of the background noise recorded one-second earlier appears to sufficiently isolate the infringement signal to allow source interpretation. Using cell phones for data downloading might allow a network of such 1000-psi rated PAMP's to acoustically monitor a pipeline system and be trained by neural network software to positively identify and locate any pipeline infringement.

  8. Field-Deployable Acoustic Digital Systems for Noise Measurement

    Science.gov (United States)

    Shams, Qamar A.; Wright, Kenneth D.; Lunsford, Charles B.; Smith, Charlie D.

    2000-01-01

    Langley Research Center (LaRC) has for years been a leader in field acoustic array measurement technique. Two field-deployable digital measurement systems have been developed to support acoustic research programs at LaRC. For several years, LaRC has used the Digital Acoustic Measurement System (DAMS) for measuring the acoustic noise levels from rotorcraft and tiltrotor aircraft. Recently, a second system called Remote Acquisition and Storage System (RASS) was developed and deployed for the first time in the field along with DAMS system for the Community Noise Flight Test using the NASA LaRC-757 aircraft during April, 2000. The test was performed at Airborne Airport in Wilmington, OH to validate predicted noise reduction benefits from alternative operational procedures. The test matrix was composed of various combinations of altitude, cutback power, and aircraft weight. The DAMS digitizes the acoustic inputs at the microphone site and can be located up to 2000 feet from the van which houses the acquisition, storage and analysis equipment. Digitized data from up to 10 microphones is recorded on a Jaz disk and is analyzed post-test by microcomputer system. The RASS digitizes and stores acoustic inputs at the microphone site that can be located up to three miles from the base station and can compose a 3 mile by 3 mile array of microphones. 16-bit digitized data from the microphones is stored on removable Jaz disk and is transferred through a high speed array to a very large high speed permanent storage device. Up to 30 microphones can be utilized in the array. System control and monitoring is accomplished via Radio Frequency (RF) link. This paper will present a detailed description of both systems, along with acoustic data analysis from both systems.

  9. Continuous wavelet transform analysis and modal location analysis acoustic emission source location for nuclear piping crack growth monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Mohd, Shukri [Nondestructive Testing Group, Industrial Technology Division, Malaysian Nuclear Agency, 43000, Bangi, Selangor (Malaysia); Holford, Karen M.; Pullin, Rhys [Cardiff School of Engineering, Cardiff University, Queen' s Buildings, The Parade, CARDIFF CF24 3AA (United Kingdom)

    2014-02-12

    Source location is an important feature of acoustic emission (AE) damage monitoring in nuclear piping. The ability to accurately locate sources can assist in source characterisation and early warning of failure. This paper describe the development of a novelAE source location technique termed 'Wavelet Transform analysis and Modal Location (WTML)' based on Lamb wave theory and time-frequency analysis that can be used for global monitoring of plate like steel structures. Source location was performed on a steel pipe of 1500 mm long and 220 mm outer diameter with nominal thickness of 5 mm under a planar location test setup using H-N sources. The accuracy of the new technique was compared with other AE source location methods such as the time of arrival (TOA) techniqueand DeltaTlocation. Theresults of the study show that the WTML method produces more accurate location resultscompared with TOA and triple point filtering location methods. The accuracy of the WTML approach is comparable with the deltaT location method but requires no initial acoustic calibration of the structure.

  10. Continuous wavelet transform analysis and modal location analysis acoustic emission source location for nuclear piping crack growth monitoring

    International Nuclear Information System (INIS)

    Shukri Mohd

    2013-01-01

    Full-text: Source location is an important feature of acoustic emission (AE) damage monitoring in nuclear piping. The ability to accurately locate sources can assist in source characterisation and early warning of failure. This paper describe the development of a novelAE source location technique termed Wavelet Transform analysis and Modal Location (WTML) based on Lamb wave theory and time-frequency analysis that can be used for global monitoring of plate like steel structures. Source location was performed on a steel pipe of 1500 mm long and 220 mm outer diameter with nominal thickness of 5 mm under a planar location test setup using H-N sources. The accuracy of the new technique was compared with other AE source location methods such as the time of arrival (TOA) technique and DeltaTlocation. The results of the study show that the WTML method produces more accurate location results compared with TOA and triple point filtering location methods. The accuracy of the WTML approach is comparable with the deltaT location method but requires no initial acoustic calibration of the structure. (author)

  11. Continuous wavelet transform analysis and modal location analysis acoustic emission source location for nuclear piping crack growth monitoring

    International Nuclear Information System (INIS)

    Mohd, Shukri; Holford, Karen M.; Pullin, Rhys

    2014-01-01

    Source location is an important feature of acoustic emission (AE) damage monitoring in nuclear piping. The ability to accurately locate sources can assist in source characterisation and early warning of failure. This paper describe the development of a novelAE source location technique termed 'Wavelet Transform analysis and Modal Location (WTML)' based on Lamb wave theory and time-frequency analysis that can be used for global monitoring of plate like steel structures. Source location was performed on a steel pipe of 1500 mm long and 220 mm outer diameter with nominal thickness of 5 mm under a planar location test setup using H-N sources. The accuracy of the new technique was compared with other AE source location methods such as the time of arrival (TOA) techniqueand DeltaTlocation. Theresults of the study show that the WTML method produces more accurate location resultscompared with TOA and triple point filtering location methods. The accuracy of the WTML approach is comparable with the deltaT location method but requires no initial acoustic calibration of the structure

  12. An efficient closed-form solution for acoustic emission source location in three-dimensional structures

    Directory of Open Access Journals (Sweden)

    Xibing Li

    2014-02-01

    Full Text Available This paper presents an efficient closed-form solution (ECS for acoustic emission(AE source location in three-dimensional structures using time difference of arrival (TDOA measurements from N receivers, N ≥ 6. The nonlinear location equations of TDOA are simplified to linear equations. The unique analytical solution of AE sources for unknown velocity system is obtained by solving the linear equations. The proposed ECS method successfully solved the problems of location errors resulting from measured deviations of velocity as well as the existence and multiplicity of solutions induced by calculations of square roots in existed close-form methods.

  13. Identification of acoustic wave propagation in a duct line and its application to detection of impact source location based on signal processing

    International Nuclear Information System (INIS)

    Shin, Yong Woo; Kim, Min Soo; Lee, Sang Kwon

    2010-01-01

    For the detection of the impact location in a pipeline system, the correlation method has been the conventional method. For the application of the correlation method, the diameter of a duct should be small so that the acoustic wave inside the duct can propagate with nondispersive characteristics, in the form of, for example, a plane wave. This correlation method calculates the cross-correlation between acoustic waves measured at two acceleration sensors attached to a buried duct. It also gives information about the arrival time delay of an acoustic wave between two sensors. These arrival time delays are used for the estimation of the impact location. However, when the diameter of the duct is large, the acoustic waves inside the duct propagate with dispersive characteristics owing to the reflection of the acoustic wave off of the wall of the duct. This dispersive characteristic is related to the acoustic modes inside a duct. Therefore, the correlation method does not work correctly for the detection of the impact location. This paper proposes new methods of accurately measuring the arrival time delay between two sensors attached to duct line system. This method is based on the time-frequency analyses of the short time Fourier transform (STFT) and continuous wavelet transform (CWT). These methods can discriminate direct waves (non-dispersive waves) and reflective waves (dispersive waves) from the measured wave signals through the time-frequency analysis. The direct wave or the reflective wave is used to estimate the arrival time delay. This delay is used for the identification of the impact location. This systematic method can predict the impact location due to the impact forces of construction equipment with more accuracy than the correlation method

  14. On-line low and high frequency acoustic leak detection and location for an automated steam generator protection system

    International Nuclear Information System (INIS)

    Gaubatz, D.C.; Gluekler, E.L.

    1990-01-01

    Two on-line acoustic leak detection systems were operated and installed on a 76 MW hockey stick steam generator in the Sodium Components Test Installation (SCTI) at the Energy Technology Engineering Center (ETEC) in Southern California. The low frequency system demonstrated the capability to detect and locate leaks, both intentional and unintentional. No false alarms were issued during the two year test program even with adjacent blasting activities, pneumatic drilling, shuttle rocket engine testing nearby, scrams of the SCTI facility, thermal/hydraulic transient testing, and pump/control valve operations. For the high frequency system the capability to detect water into sodium reactions was established utilizing frequencies as high as 300 kHz. The high frequency system appeared to be sensitive to noise generated by maintenance work and system valve operations. Subsequent development work which is incomplete as of this date showed much more promise for the high frequency system. (author). 13 figs

  15. System for detecting acoustic emissions in multianvil experiments: Application to deep seismicity in the Earth

    International Nuclear Information System (INIS)

    Jung, Haemyeong; Fei Yingwei; Silver, Paul G.; Green, Harry W.

    2006-01-01

    One of the major goals in the experimental study of deep earthquakes is to identify slip instabilities at high pressure and high temperature (HPHT) that might be responsible for the occurrence of earthquakes. Detecting acoustic emissions from a specimen during faulting provides unique constraints on the instability process. There are few experimental studies reporting acoustic emissions under HPHT conditions, due to technical challenges. And those studies have used only one or at most two acoustic sensors during the experiments. Such techniques preclude the accurate location of the acoustic emission source region and thus the ability to distinguish real signal from noise that may be coming from outside the sample. We have developed a system for detecting acoustic emissions at HPHT. Here we present a four-channel acoustic emission detecting system working in the HPHT octahedral multianvil apparatus. Each channel has high resolution (12 bits) and a sampling rate of 30 MHz. In experiments at the pressures up to 6 GPa and temperatures up to 770 deg. C, we have observed acoustic emissions under various conditions. Analyzing these signals, we are able to show that this system permits us to distinguish between signal and noise, locate the source of the acoustic emission, and obtain reliable data on the radiation pattern. This system has greatly improved our ability to study faulting instabilities under high pressure and high temperature

  16. Challenges in Locating Microseismic Events Using Distributed Acoustic Sensors

    Science.gov (United States)

    Williams, A.; Kendall, J. M.; Clarke, A.; Verdon, J.

    2017-12-01

    Microseismic monitoring is an important method of assessing the behaviour of subsurface fluid processes, and is commonly acquired using geophone arrays in boreholes or on the surface. A new alternative technology has been recently developed - fibre-optic Distributed Acoustic Sensing (DAS) - using strain along a fibre-optic cable as a measure of seismic signals. DAS can offer high density arrays and full-well coverage from the surface to bottom, with less overall disruption to operations, so there are many exciting possible applications in monitoring both petroleum and other subsurface industries. However, there are challenges in locating microseismic events recorded using current DAS systems, which only record seismic data in one-component and consequently omit the azimuthal information provided by a three-component geophone. To test the impact of these limitations we used finite difference modelling to generate one-component synthetic DAS datasets and investigated the impact of picking solely P-wave or both P- and S-wave arrivals and the impact of different array geometries. These are then compared to equivalent 3-component synthetic geophone datasets. In simple velocity models, P-wave arrivals along linear arrays cannot be used to constrain locations using DAS, without further a priori information. We then tested the impact of straight cables vs. L-shaped arrays and found improved locations when the cable is deviated, especially when both P- and S-wave picks are included. There is a trade-off between the added coverage of DAS cables versus sparser 3C geophone arrays where particle motion helps constrains locations, which cannot be assessed without forward modelling.

  17. Measurement of acoustic characteristics of Japanese Buddhist temples in relation to sound source location and direction.

    Science.gov (United States)

    Soeta, Yoshiharu; Shimokura, Ryota; Kim, Yong Hee; Ohsawa, Tomohiro; Ito, Ken

    2013-05-01

    Although temples are important buildings in the Buddhist community, the acoustic quality has not been examined in detail. Buddhist monks change the location and direction according to the ceremony, and associated acoustical changes have not yet been examined scientifically. To discuss the desired acoustics of temples, it is necessary to know the acoustic characteristics appropriate for each phase of a ceremony. In this study, acoustic measurements were taken at various source locations and directions in Japanese temples. A directional loudspeaker was used as the source to provide vocal acoustic fields, and impulse responses were measured and analyzed. The speech transmission index was higher and the interaural cross-correlation coefficient was lower for the sound source directed toward the side wall than that directed toward the altar. This suggests that the change in direction improves speech intelligibility, and the asymmetric property of direct sound and complex reflections from the altar and side wall increases the apparent source width. The large and coupled-like structure of the altar of a Buddhist temple may have reinforced the reverberation components and the table in the altar, which is called the "syumidan," may have decreased binaural coherence.

  18. Experimental study on a de-noising system for gas and oil pipelines based on an acoustic leak detection and location method

    International Nuclear Information System (INIS)

    Liu, Cuiwei; Li, Yuxing; Fang, Liping; Xu, Minghai

    2017-01-01

    To protect the pipelines from significant danger, the acoustic leak detection and location method for oil and gas pipelines is studied, and a de-noising system is established to extract leakage characteristics from signals. A test loop for gas and oil is established to carry out experiments. First, according to the measured signals, fitting leakage signals are obtained, and then, the objective signals are constructed by adding noises to the fitting signals. Based on the proposed evaluation indexes, the filtering methods are then applied to process the constructed signals and the de-noising system is established. The established leakage extraction system is validated and then applied to process signals measured in gas pipelines that include a straight pipe, elbow pipe and reducing pipe. The leak detection and location is carried out effectively. Finally, the system is applied to process signals measured in water pipelines. The results demonstrate that the proposed de-noising system is effective at extracting leakage signals from measured signals and that the proposed leak detection and location method has a higher detection sensitivity and localization accuracy. For a pipeline with an inner diameter of 42 mm, the smallest leakage orifice that can be detected is 0.1 mm for gas and water and the largest location error is 0.874% for gas and 0.176% for water. - Highlights: • Three evaluation indexes are proposed: SNR, RMSE and ALPD. • The de-noising system is established in the gas and oil pipelines. • The established system is used for gas pipeline effectively, including interference pipes. • The established de-noising system is used for water pipeline effectively.

  19. Guided acoustic wave inspection system

    Science.gov (United States)

    Chinn, Diane J.

    2004-10-05

    A system for inspecting a conduit for undesirable characteristics. A transducer system induces guided acoustic waves onto said conduit. The transducer system detects the undesirable characteristics of the conduit by receiving guided acoustic waves that contain information about the undesirable characteristics. The conduit has at least two sides and the transducer system utilizes flexural modes of propagation to provide inspection using access from only the one side of the conduit. Cracking is detected with pulse-echo testing using one transducer to both send and receive the guided acoustic waves. Thinning is detected in through-transmission testing where one transducer sends and another transducer receives the guided acoustic waves.

  20. Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors

    Science.gov (United States)

    Zuckerwar, Allan J. (Inventor); Davis, David C. (Inventor)

    1995-01-01

    An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.

  1. Development of an Acoustic Levitation Linear Transportation System Based on a Ring-Type Structure.

    Science.gov (United States)

    Thomas, Gilles P L; Andrade, Marco A B; Adamowski, Julio Cezar; Silva, Emilio Carlos Nelli

    2017-05-01

    A linear acoustic levitation transportation system based on a ring-type vibrator is presented. The system is composed by two 21-kHz Langevin transducers connected to a ring-shaped structure formed by two semicircular sections and two flat plates. In this system, a flexural standing wave is generated along the ring structure, producing an acoustic standing wave between the vibrating ring and a plane reflector located at a distance of approximately a half wavelength from the ring. The acoustic standing wave in air has a series of pressure nodes, where small particles can be levitated and transported. The ring-type transportation system was designed and analyzed by using the finite element method. Additionally, a prototype was built and the acoustic levitation and transport of a small polystyrene particle was demonstrated.

  2. Acoustic imaging system

    Science.gov (United States)

    Smith, Richard W.

    1979-01-01

    An acoustic imaging system for displaying an object viewed by a moving array of transducers as the array is pivoted about a fixed point within a given plane. A plurality of transducers are fixedly positioned and equally spaced within a laterally extending array and operatively directed to transmit and receive acoustic signals along substantially parallel transmission paths. The transducers are sequentially activated along the array to transmit and receive acoustic signals according to a preestablished sequence. Means are provided for generating output voltages for each reception of an acoustic signal, corresponding to the coordinate position of the object viewed as the array is pivoted. Receptions from each of the transducers are presented on the same display at coordinates corresponding to the actual position of the object viewed to form a plane view of the object scanned.

  3. Acoustic Emission Source Location Using a Distributed Feedback Fiber Laser Rosette

    Directory of Open Access Journals (Sweden)

    Fang Li

    2013-10-01

    Full Text Available This paper proposes an approach for acoustic emission (AE source localization in a large marble stone using distributed feedback (DFB fiber lasers. The aim of this study is to detect damage in structures such as those found in civil applications. The directional sensitivity of DFB fiber laser is investigated by calculating location coefficient using a method of digital signal analysis. In this, autocorrelation is used to extract the location coefficient from the periodic AE signal and wavelet packet energy is calculated to get the location coefficient of a burst AE source. Normalization is processed to eliminate the influence of distance and intensity of AE source. Then a new location algorithm based on the location coefficient is presented and tested to determine the location of AE source using a Delta (Δ DFB fiber laser rosette configuration. The advantage of the proposed algorithm over the traditional methods based on fiber Bragg Grating (FBG include the capability of: having higher strain resolution for AE detection and taking into account two different types of AE source for location.

  4. Perancangan Prototipe Receiver Beacon Black Box Locator Acoustic 37,5 kHz Pingers

    OpenAIRE

    RUSTAMAJI RUSTAMAJI; PAULINE RAHMIATI; SARAH PERMATASARI

    2016-01-01

    ABSTRAK Ketika suatu pesawat terbang mengalami kecelakaan terjatuh ke dalam air, maka lokasi keberadaannya dapat dideteksi oleh alat yang disebut receiver beacon black box locator acoustic (pingers receiver). Pingers receiver berfungsi untuk menerima sinyal dengan frekuensi 37,5 kHz ± 1 kHz dari pingers transmitter atau Underwater Locator Beacon (ULB) yang berada pada black box pesawat. Dalam penelitian ini dibuat perancangan pingers receiver yang tersusun dari rangkaian Band Pass Filter (BPF...

  5. Acoustic transducer in system for gas temperature measurement in gas turbine engine

    Science.gov (United States)

    DeSilva, Upul P.; Claussen, Heiko

    2017-07-04

    An apparatus for controlling operation of a gas turbine engine including at least one acoustic transmitter/receiver device located on a flow path boundary structure. The acoustic transmitter/receiver device includes an elongated sound passage defined by a surface of revolution having opposing first and second ends and a central axis extending between the first and second ends, an acoustic sound source located at the first end, and an acoustic receiver located within the sound passage between the first and second ends. The boundary structure includes an opening extending from outside the boundary structure to the flow path, and the second end of the surface of revolution is affixed to the boundary structure at the opening for passage of acoustic signals between the sound passage and the flow path.

  6. The deep sea Acoustic Detection system AMADEUS

    International Nuclear Information System (INIS)

    Naumann, Christopher Lindsay

    2008-01-01

    As a part of the ANTARES neutrino telescope, the AMADEUS (ANTARES Modules for Acoustic Detection Under the Sea) system is an array of acoustical sensors designed to investigate the possibilities of acoustic detection of ultra-high energy neutrinos in the deep sea. The complete system will comprise a total of 36 acoustic sensors in six clusters on two of the ANTARES detector lines. With an inter-sensor spacing of about one metre inside the clusters and between 15 and 340 metres between the different clusters, it will cover a wide range of distances as will as provide a considerable lever arm for point source triangulation. Three of these clusters have already been deployed in 2007 and have been in operation since, currently yielding around 2GB of acoustic data per day. The remaining three clusters are scheduled to be deployed in May 2008 together with the final ANTARES detector line. Apart from proving the feasibility of operating an acoustic detection system in the deep sea, the main aim of this project is an in-depth survey of both the acoustic properties of the sea water and the acoustic background present at the detector site. It will also serve as a platform for the development and refinement of triggering, filtering and reconstruction algorithms for acoustic particle detection. In this presentation, a description of the acoustic sensor and read-out system is given, together with examples for the reconstruction and evaluation of the acoustic data.

  7. Acoustic-phonetic cues to word boundary location: Evidence from word spotting

    OpenAIRE

    Dumay, Nicolas; Content, Alain; Frauenfelder, Ulrich Hans

    1999-01-01

    This research examined acoustic-phonetic cues to word boundary location in French consonant clusters, and assessed their use in on-line lexical segmentation. Two word-spotting experiments manipulated the alignment between word targets and syllable boundaries. A perceptual cost of such misalignment was observed for obstruent-liquid clusters but not for /s/ + obstruent clusters. For the former clusters, the analysis of a corpus of utterances showed systematic variations in segment durations as ...

  8. Acoustic analysis of a piping system

    International Nuclear Information System (INIS)

    Misra, A.S.; Vijay, D.K.

    1996-01-01

    Acoustic pulsations in the Darlington Nuclear Generating Station, a 881 MW CANDU, primary heat transport piping system caused fuel bundle failures under short term operations. The problem was successfully analyzed using the steady-state acoustic analysis capability of the ABAQUS program. This paper describes in general, modelling of low amplitude acoustic pulsations in a liquid filled piping system using ABAQUS. The paper gives techniques for estimating the acoustic medium properties--bulk modulus, fluid density and acoustic damping--and modelling fluid-structure interactions at orifices and elbows. The formulations and techniques developed are benchmarked against the experiments given in 3 cited references. The benchmark analysis shows that the ABAQUS results are in excellent agreement with the experiments

  9. Crack Propagation Analysis Using Acoustic Emission Sensors for Structural Health Monitoring Systems

    Science.gov (United States)

    Horn, Walter; Steck, James

    2013-01-01

    Aerospace systems are expected to remain in service well beyond their designed life. Consequently, maintenance is an important issue. A novel method of implementing artificial neural networks and acoustic emission sensors to form a structural health monitoring (SHM) system for aerospace inspection routines was the focus of this research. Simple structural elements, consisting of flat aluminum plates of AL 2024-T3, were subjected to increasing static tensile loading. As the loading increased, designed cracks extended in length, releasing strain waves in the process. Strain wave signals, measured by acoustic emission sensors, were further analyzed in post-processing by artificial neural networks (ANN). Several experiments were performed to determine the severity and location of the crack extensions in the structure. ANNs were trained on a portion of the data acquired by the sensors and the ANNs were then validated with the remaining data. The combination of a system of acoustic emission sensors, and an ANN could determine crack extension accurately. The difference between predicted and actual crack extensions was determined to be between 0.004 in. and 0.015 in. with 95% confidence. These ANNs, coupled with acoustic emission sensors, showed promise for the creation of an SHM system for aerospace systems. PMID:24023536

  10. A Practical Method of Acoustic Emission Source Location in Anisotropic Composite Laminates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Kon; Kang, Yong Kyu; Kwon, Oh Yang [Inha University, Incheon (Korea, Republic of)

    2003-06-15

    Since the velocity is dependent on the fiber orientation in anisotropic composites, the application of traditional acoustic emission (AE) source location techniques based on the constant velocity to composite structures has been practically impossible. The anisotropy makes the source location procedure complicated and deteriorates the accuracy of the location. In this study, we have divided the region of interest(ROI) into a set of finite elements, taken each element as a virtual source, and calculated the arrival time differences between sensors by using the velocities at every degree from 0 to 90. The calculated and the experimentally measured values of the arrival time difference aye then compared to minimize the location error. The results from two different materials, namely AA6061-T6 and CFRP(uni-directional; UD, [0]{sub 32}4 ) laminate confirmed the practical usefulness of the proposed method

  11. ISAT: The mega-fauna acoustic tracking system

    KAUST Repository

    De la Torre, Pedro; Smith, Egan Lloyd; Sancheti, Ajay; Salama, Khaled N.; Berumen, Michael L.

    2013-01-01

    The acoustic tracking module of the Integrated Satellite and Acoustic Telemetry (iSAT) system is discussed in detail. iSAT is capable of detecting the relative direction of an acoustic source by measuring the order of arrival (OOA) of the acoustic

  12. Acoustic Test Results of Melamine Foam with Application to Payload Fairing Acoustic Attenuation Systems

    Science.gov (United States)

    Hughes, William O.; McNelis, Anne M.

    2014-01-01

    A spacecraft at launch is subjected to a harsh acoustic and vibration environment resulting from the passage of acoustic energy, created during the liftoff of a launch vehicle, through the vehicle's payload fairing. In order to ensure the mission success of the spacecraft it is often necessary to reduce the resulting internal acoustic sound pressure levels through the usage of acoustic attenuation systems. Melamine foam, lining the interior walls of the payload fairing, is often utilized as the main component of such a system. In order to better understand the acoustic properties of melamine foam, with the goal of developing improved acoustic attenuation systems, NASA has recently performed panel level testing on numerous configurations of melamine foam acoustic treatments at the Riverbank Acoustical Laboratory. Parameters assessed included the foam's thickness and density, as well as the effects of a top outer cover sheet material and mass barriers embedded within the foam. This testing followed the ASTM C423 standard for absorption and the ASTM E90 standard for transmission loss. The acoustic test data obtained and subsequent conclusions are the subjects of this paper.

  13. Design and first tests of an acoustic positioning and detection system for KM3NeT

    Science.gov (United States)

    Simeone, F.; Ameli, F.; Ardid, M.; Bertin, V.; Bonori, M.; Bou-Cabo, M.; Calì, C.; D'Amico, A.; Giovanetti, G.; Imbesi, M.; Keller, P.; Larosa, G.; Llorens, C. D.; Masullo, R.; Randazzo, N.; Riccobene, G.; Speziale, F.; Viola, S.; KM3NeT Consortium

    2012-01-01

    In a deep-sea neutrino telescope it is mandatory to locate the position of the optical sensors with a precision of about 10 cm. To achieve this requirement, an innovative Acoustic Positioning System (APS) has been designed in the frame work of the KM3NeT neutrino telescope. The system will also be able to provide an acoustic guide during the deployment of the telescope’s components and seafloor infrastructures (junction boxes, cables, etc.). A prototype of the system based on the successful acoustic systems of ANTARES and NEMO is being developed. It will consist of an array of hydrophones and a network of acoustic transceivers forming the Long Baseline. All sensors are connected to the telescope data acquisition system and are in phase and synchronised with the telescope master clock. Data from the acoustic sensors, continuously sampled at 192 kHz, will be sent to shore where signal recognition and analysis will be carried out. The design and first tests of the system elements will be presented. This new APS is expected to have better precision compared to the systems used in ANTARES and NEMO, and can also be used as a real-time monitor of acoustic sources and environmental noise in deep sea.

  14. LOCATING LEAKS WITH ACOUSTIC TECHNOLOGY

    Science.gov (United States)

    Many water distribution systems in this country are almost 100 years old. About 26 percent of piping in these systems is made of unlined cast iron or steel and is in poor condition. Many methods that locate leaks in these pipes are time-consuming, costly, disruptive to operations...

  15. Acoustic emission leak monitoring system LMS-96

    International Nuclear Information System (INIS)

    Liska, J.; Cvrcek, M.; Mueller, L.

    1997-01-01

    On-line acoustic emission leak monitoring under industrial conditions of nuclear power plants is a problem with specific features setting specific demands on the leak monitoring system. The paper briefly reviews those problems (attenuation pattern of a real structure, acoustic background, alarm system, etc.) and the solution of some of them is discussed. Information is presented on the Acoustic Emission Leak Monitoring System LMS-96 by SKODA NUCLEAR MACHINERY and the system's function is briefly described. (author)

  16. Acoustic emission linear pulse holography

    Science.gov (United States)

    Collins, H.D.; Busse, L.J.; Lemon, D.K.

    1983-10-25

    This device relates to the concept of and means for performing Acoustic Emission Linear Pulse Holography, which combines the advantages of linear holographic imaging and Acoustic Emission into a single non-destructive inspection system. This unique system produces a chronological, linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. The innovation is the concept of utilizing the crack-generated acoustic emission energy to generate a chronological series of images of a growing crack by applying linear, pulse holographic processing to the acoustic emission data. The process is implemented by placing on a structure an array of piezoelectric sensors (typically 16 or 32 of them) near the defect location. A reference sensor is placed between the defect and the array.

  17. Leak detection and localization system through acoustics; Sistema de deteccao e localizacao de vazamentos por acustica

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, Julio [Aselco Automacao, Sao Paulo, SP (Brazil)

    2003-07-01

    Acoustic Leak Detection Systems (ALDS) are used on both liquid and gas pipelines as well as multi-phase flow pipelines to detect leaks quickly and provide a means of limiting product loss. The real-time acoustic signal is continuously compared against signature leak profiles for the particular operating and geometric conditions. These profiles were developed from a database established from over 20 years of experimental and field leak tests. This technique not only drastically reduces the false alarm rate, but also significantly improves the sensitivity and leak location accuracy. This system will also detect leaks with shut-in flow (zero flow rate in the pipeline). With the use of GPS (Global Positioning System) it not only improves leak location accuracy, but also allows for continuous leak detection during the loss of communications. (author)

  18. Dimensional feature weighting utilizing multiple kernel learning for single-channel talker location discrimination using the acoustic transfer function.

    Science.gov (United States)

    Takashima, Ryoichi; Takiguchi, Tetsuya; Ariki, Yasuo

    2013-02-01

    This paper presents a method for discriminating the location of the sound source (talker) using only a single microphone. In a previous work, the single-channel approach for discriminating the location of the sound source was discussed, where the acoustic transfer function from a user's position is estimated by using a hidden Markov model of clean speech in the cepstral domain. In this paper, each cepstral dimension of the acoustic transfer function is newly weighted, in order to obtain the cepstral dimensions having information that is useful for classifying the user's position. Then, this paper proposes a feature-weighting method for the cepstral parameter using multiple kernel learning, defining the base kernels for each cepstral dimension of the acoustic transfer function. The user's position is trained and classified by support vector machine. The effectiveness of this method has been confirmed by sound source (talker) localization experiments performed in different room environments.

  19. Acoustic emission monitoring during hydrotests of a thin wall pressure vessel

    International Nuclear Information System (INIS)

    Fontana, E.; Grugni, G.; Panzani, C.; Pirovano, B.; Possa, G.; Tonolini, F.

    1975-01-01

    The results are presented of an acoustic emission monitoring performed during hydrotests of a thin wall steel pressure vessel. The location of acoustic sources was based on longitudinal wave front detection. The careful calibration of the three sensors instrumentation system used for acoustic source location was found to be useful, and alllowed an accurate location error analysis. Acoustic emission in the hydrotests was found to be mainly due to stress release in weld seams. (Fontana, E.; Grugni, G.; Panzani, C.; Pirovano, B.; Possa, G.; Tonolini, F.)

  20. Acoustic location of conspecifics in a nocturnal bird: the corncrake Crex crex

    OpenAIRE

    Ręk, Paweł

    2013-01-01

    Although the use of sounds in spatial orientation is widespread among animals, only a few groups advanced such specific adaptations as echolocation. In contrast, practically all animals and night-active species in particular, must occasionally orient themselves relative to invisible but audible objects such as a hidden rival or predator. In this study, I would like to determine the impact of locating which involves the use of acoustic parameters of sender’s vocalisations by receivers and chan...

  1. Multipole expansion of acoustical Bessel beams with arbitrary order and location.

    Science.gov (United States)

    Gong, Zhixiong; Marston, Philip L; Li, Wei; Chai, Yingbin

    2017-06-01

    An exact solution of expansion coefficients for a T-matrix method interacting with acoustic scattering of arbitrary order Bessel beams from an obstacle of arbitrary location is derived analytically. Because of the failure of the addition theorem for spherical harmonics for expansion coefficients of helicoidal Bessel beams, an addition theorem for cylindrical Bessel functions is introduced. Meanwhile, an analytical expression for the integral of products including Bessel and associated Legendre functions is applied to eliminate the integration over the polar angle. Note that this multipole expansion may also benefit other scattering methods and expansions of incident waves, for instance, partial-wave series solutions.

  2. Gravity enhanced acoustic levitation method and apparatus

    Science.gov (United States)

    Barmatz, M. B.; Allen, J. L.; Granett, D. (Inventor)

    1985-01-01

    An acoustic levitation system is provided for acoustically levitating an object by applying a single frequency from a transducer into a resonant chamber surrounding the object. The chamber includes a stabilizer location along its height, where the side walls of the chamber are angled so they converge in an upward direction. When an acoustic standing wave pattern is applied between the top and bottom of the chamber, a levitation surface within the stabilizer does not lie on a horizontal plane, but instead is curved with a lowermost portion near the vertical axis of the chamber. As a result, an acoustically levitated object is urged by gravity towards the lowermost location on the levitation surface, so the object is kept away from the side walls of the chamber.

  3. ISAT: The mega-fauna acoustic tracking system

    KAUST Repository

    De la Torre, Pedro

    2013-06-01

    The acoustic tracking module of the Integrated Satellite and Acoustic Telemetry (iSAT) system is discussed in detail. iSAT is capable of detecting the relative direction of an acoustic source by measuring the order of arrival (OOA) of the acoustic signal to each hydrophone in a triangular array. The characteristics of the hydrophones, the projector, and the target acoustic signal used for iSAT are described. Initially it is designed to study the movements of whale sharks (Rhincodon typus), but it could potentially be used to describe high resolution movements of other marine species. © 2013 IEEE.

  4. Acoustic Localization with Infrasonic Signals

    Science.gov (United States)

    Threatt, Arnesha; Elbing, Brian

    2015-11-01

    Numerous geophysical and anthropogenic events emit infrasonic frequencies (<20 Hz), including volcanoes, hurricanes, wind turbines and tornadoes. These sounds, which cannot be heard by the human ear, can be detected from large distances (in excess of 100 miles) due to low frequency acoustic signals having a very low decay rate in the atmosphere. Thus infrasound could be used for long-range, passive monitoring and detection of these events. An array of microphones separated by known distances can be used to locate a given source, which is known as acoustic localization. However, acoustic localization with infrasound is particularly challenging due to contamination from other signals, sensitivity to wind noise and producing a trusted source for system development. The objective of the current work is to create an infrasonic source using a propane torch wand or a subwoofer and locate the source using multiple infrasonic microphones. This presentation will present preliminary results from various microphone configurations used to locate the source.

  5. Subwavelength image manipulation through oblique and herringbone layered acoustic systems

    International Nuclear Information System (INIS)

    Li, Chunhui; Jia, Han; Ke, Manzhu; Li, Yixiang; Liu, Zhengyou

    2014-01-01

    In this paper, an oblique and a herringbone layered acoustic structure are experimentally and theoretically demonstrated to manipulate acoustic subwavelength images. An imaging resolution of less than one tenth of a wavelength is achieved with both optimized systems, and lateral image shift has been realized by an oblique layered system. The thicknesses of both the oblique and the herringbone layered acoustic systems are largely reduced through utilizing the oblique or herringbone wave propagation path instead of the vertical wave propagation path in the rectangular layered planar acoustic system. With smaller size and subwavelength image manipulation, the acoustic systems are more favourable for practical application. (paper)

  6. Streaming and particle motion in acoustically-actuated leaky systems

    Science.gov (United States)

    Nama, Nitesh; Barnkob, Rune; Jun Huang, Tony; Kahler, Christian; Costanzo, Francesco

    2017-11-01

    The integration of acoustics with microfluidics has shown great promise for applications within biology, chemistry, and medicine. A commonly employed system to achieve this integration consists of a fluid-filled, polymer-walled microchannel that is acoustically actuated via standing surface acoustic waves. However, despite significant experimental advancements, the precise physical understanding of such systems remains a work in progress. In this work, we investigate the nature of acoustic fields that are setup inside the microchannel as well as the fundamental driving mechanism governing the fluid and particle motion in these systems. We provide an experimental benchmark using state-of-art 3D measurements of fluid and particle motion and present a Lagrangian velocity based temporal multiscale numerical framework to explain the experimental observations. Following verification and validation, we employ our numerical model to reveal the presence of a pseudo-standing acoustic wave that drives the acoustic streaming and particle motion in these systems.

  7. Underwater Acoustic Beacon Location System

    Science.gov (United States)

    2016-12-23

    frequency band is presented to the operator as a function of time and beam angle in a three dimensional “ waterfall ” display 210. [0046] As shown in FIG...and Down (zn) relative to the World Geodetic System (WGS 84) ellipsoid model [NIMA Technical Report TR8350.2, Chapter 3 “Department of Defense

  8. Dynamic response of piping system subject to flow acoustic excitation

    International Nuclear Information System (INIS)

    Wang, T.; Sun, Y.S.

    1988-01-01

    Through the use of a theoretically derived and test data-calibrated forcing function, the dynamic response of a piping system subject to flow-acoustic induced vibration is analyzed. It is shown that the piping behavior can be predicted when consideration is given to both the wall flexural vibration and the piping system vibration. Piping responded as a system to the transversal excitation due to the swirling motion of the fluid flow, as well as flexurally to the high-frequency acoustic excitations. The transverse piping system response was calculated using a lumped mass piping model. The piping model has more stringent requirements than its counterpart for waterhammer and seismic modeling due to the shorter spiral wavelength and higher frequency of the forcing function. Proper modeling ensured that both the moment stress caused by system excitation and the local stress induced by the support reaction load were properly accounted for. Flexural vibration not only poses a threat to nipples and branch connections, but also contributes substantially to the resultant total stress experienced by the pipe. The forcing function approach has the advantage that the critical locations on the piping system can be identified by means of analysis, facilitating surveillance and inspection, as well as fatigue evaluation

  9. Characterization of Pump-Induced Acoustics in Space Launch System Main Propulsion System Liquid Hydrogen Feedline Using Airflow Test Data

    Science.gov (United States)

    Eberhart, C. J.; Snellgrove, L. M.; Zoladz, T. F.

    2015-01-01

    High intensity acoustic edgetones located upstream of the RS-25 Low Pressure Fuel Turbo Pump (LPFTP) were previously observed during Space Launch System (STS) airflow testing of a model Main Propulsion System (MPS) liquid hydrogen (LH2) feedline mated to a modified LPFTP. MPS hardware has been adapted to mitigate the problematic edgetones as part of the Space Launch System (SLS) program. A follow-on airflow test campaign has subjected the adapted hardware to tests mimicking STS-era airflow conditions, and this manuscript describes acoustic environment identification and characterization born from the latest test results. Fluid dynamics responsible for driving discrete excitations were well reproduced using legacy hardware. The modified design was found insensitive to high intensity edgetone-like discretes over the bandwidth of interest to SLS MPS unsteady environments. Rather, the natural acoustics of the test article were observed to respond in a narrowband-random/mixed discrete manner to broadband noise thought generated by the flow field. The intensity of these responses were several orders of magnitude reduced from those driven by edgetones.

  10. Extreme Low Frequency Acoustic Measurement System

    Science.gov (United States)

    Shams, Qamar A. (Inventor); Zuckerwar, Allan J. (Inventor)

    2017-01-01

    The present invention is an extremely low frequency (ELF) microphone and acoustic measurement system capable of infrasound detection in a portable and easily deployable form factor. In one embodiment of the invention, an extremely low frequency electret microphone comprises a membrane, a backplate, and a backchamber. The backchamber is sealed to allow substantially no air exchange between the backchamber and outside the microphone. Compliance of the membrane may be less than ambient air compliance. The backplate may define a plurality of holes and a slot may be defined between an outer diameter of the backplate and an inner wall of the microphone. The locations and sizes of the holes, the size of the slot, and the volume of the backchamber may be selected such that membrane motion is substantially critically damped.

  11. Performance analysis of an acoustic time reversal system in dynamic and random oceanic environments

    Science.gov (United States)

    Khosla, Sunny Rajendra

    This dissertation provides a theoretical framework along with specific performance predictions for an acoustic time reversal system in shallow oceanic environments. Acoustic time-reversal is a robust means of retrofocusing acoustic energy, in both time and space, to the original sound-source location without any information about the acoustic environment in which it is deployed. The effect of three performance limiting oceanic complexities addressed, include (i)ambient noise field, (ii)reflection and volume scattering from a deterministic soliton internal wave traveling on the thermocline between two water masses, and (iii)volume scattering from a random superposition of linear internal waves convecting a gradient in the sound speed profile. The performance analysis establishes acoustic time reversal to be a promising technology for a two-way communication system in an oceanic medium. For an omni-directional noisy environment a general formulation for the probability of retrofocusing is developed that includes the effect of the medium, accounts for the system hardware and the acoustic parameters. Monte-Carlo simulations in both, a free-space environment and a shallow-ocean sound-channel environment compare well with theory. A 41 element TRA spanning a shallow water depth of 60 m is predicted to return a 70% focal probability at -15 dB SNR for a source to array range of 6 km. Preliminary research with broadband signals suggest that they should outperform narrowband response in both free space and sound channel environments. The impact of the nonlinear solitary waves is addressed using a two-path Green's function to treat the presence of a flat thermocline, and the single scattering Born approximation to address scattering from the soliton internal wave. It is predicted that a stationary soliton located along ray turning paths between the source and the TRA can lead to both enhanced and degraded focal performance. Based on extension of previous research in wave

  12. Planar location of the simulative acoustic source based on fiber optic sensor array

    Science.gov (United States)

    Liang, Yi-Jun; Liu, Jun-feng; Zhang, Qiao-ping; Mu, Lin-lin

    2010-06-01

    A fiber optic sensor array which is structured by four Sagnac fiber optic sensors is proposed to detect and locate a simulative source of acoustic emission (AE). The sensing loops of Sagnac interferometer (SI) are regarded as point sensors as their small size. Based on the derived output light intensity expression of SI, the optimum work condition of the Sagnac fiber optic sensor is discussed through the simulation of MATLAB. Four sensors are respectively placed on a steel plate to structure the sensor array and the location algorithms are expatiated. When an impact is generated by an artificial AE source at any position of the plate, the AE signal will be detected by four sensors at different times. With the help of a single chip microcomputer (SCM) which can calculate the position of the AE source and display it on LED, we have implemented an intelligent detection and location.

  13. Optimization of a Biometric System Based on Acoustic Images

    Directory of Open Access Journals (Sweden)

    Alberto Izquierdo Fuente

    2014-01-01

    Full Text Available On the basis of an acoustic biometric system that captures 16 acoustic images of a person for 4 frequencies and 4 positions, a study was carried out to improve the performance of the system. On a first stage, an analysis to determine which images provide more information to the system was carried out showing that a set of 12 images allows the system to obtain results that are equivalent to using all of the 16 images. Finally, optimization techniques were used to obtain the set of weights associated with each acoustic image that maximizes the performance of the biometric system. These results improve significantly the performance of the preliminary system, while reducing the time of acquisition and computational burden, since the number of acoustic images was reduced.

  14. Optimization of a Biometric System Based on Acoustic Images

    Science.gov (United States)

    Izquierdo Fuente, Alberto; Del Val Puente, Lara; Villacorta Calvo, Juan J.; Raboso Mateos, Mariano

    2014-01-01

    On the basis of an acoustic biometric system that captures 16 acoustic images of a person for 4 frequencies and 4 positions, a study was carried out to improve the performance of the system. On a first stage, an analysis to determine which images provide more information to the system was carried out showing that a set of 12 images allows the system to obtain results that are equivalent to using all of the 16 images. Finally, optimization techniques were used to obtain the set of weights associated with each acoustic image that maximizes the performance of the biometric system. These results improve significantly the performance of the preliminary system, while reducing the time of acquisition and computational burden, since the number of acoustic images was reduced. PMID:24616643

  15. Vibro-acoustic modeling and analysis of a coupled acoustic system comprising a partially opened cavity coupled with a flexible plate

    Science.gov (United States)

    Shi, Shuangxia; Su, Zhu; Jin, Guoyong; Liu, Zhigang

    2018-01-01

    This paper is concerned with the modeling and solution method of a three-dimensional (3D) coupled acoustic system comprising a partially opened cavity coupled with a flexible plate and an exterior field of semi-infinite size, which is ubiquitously encountered in architectural acoustics and is a reasonable representation of many engineering occasions. A general solution method is presented to predict the dynamic behaviors of the three-dimensional (3D) acoustic coupled system, in which the displacement of the plate and the sound pressure in the cavity are respectively constructed in the form of the two-dimensional and three-dimensional modified Fourier series with several auxiliary functions introduced to ensure the uniform convergence of the solution over the entire solution domain. The effect of the opening is taken into account via the work done by the sound pressure acting at the coupling aperture that is contributed from the vibration of particles on the acoustic coupling interface and on the structural-acoustic coupling interface. Both the acoustic coupling between finite cavity and exterior field and the structural-acoustic coupling between flexible plate and interior acoustic field are considered in the vibro-acoustic modeling of the three-dimensional acoustic coupled acoustic system. The dynamic responses of the coupled structural-acoustic system are obtained using the Rayleigh-Ritz procedure based on the energy expressions for the coupled system. The accuracy and effectiveness of the proposed method are validated through numerical examples and comparison with results obtained by the boundary element analysis. Furthermore, the influence of the opening and the cavity volume on the acoustic behaviors of opened cavity system is studied.

  16. Distributed acoustic sensing with Michelson interferometer demodulation

    Science.gov (United States)

    Liu, Xiaohui; Wang, Chen; Shang, Ying; Wang, Chang; Zhao, Wenan; Peng, Gangding; Wang, Hongzhong

    2017-09-01

    The distributed acoustic sensing (DAS) has been extensively studied and widely used. A distributed acoustic sensing system based on the unbalanced Michelson interferometer with phase generated carrier (PGC) demodulation was designed and tested. The system could directly obtain the phase, amplitude, frequency response, and location information of sound wave at the same time and measurement at all points along the sensing fiber simultaneously. Experiments showed that the system successfully measured the acoustic signals with a phase-pressure sensitivity about-148 dB (re rad/μPa) and frequency response ripple less than 1.5 dB. The further field experiment showed that the system could measure signals at all points along the sensing fiber simultaneously.

  17. Three-dimensional Acoustic Localisation via Directed Movements of a Two-dimensional Model of the Lizard Peripheral Auditory System

    DEFF Research Database (Denmark)

    Shaikh, Danish; Kjær Schmidt, Michael

    2017-01-01

    of the acoustic target with respect to one plane of rotation. A multi-layer perceptron neural network is trained via supervised learning to translate the combination of the two measurements into an estimate of the relative location of the acoustic target in terms of its azimuth and elevation. The acoustic...... localisation performance of the system is evaluated in simulation for noiseless as well as noisy sinusoidal auditory signals with a 20 dB signal-to-noise ratio for four different sound frequencies of 1450 Hz, 1650 Hz, 1850 Hz and 2050 Hz that span the response frequency range of the peripheral auditory model...

  18. Radiation-acoustic system for solid state research

    International Nuclear Information System (INIS)

    Zalyubovsky, I.I.; Kalinichenko, A.I.; Kresnin, Yu.; Popov, G.F.

    1998-01-01

    The radiation-acoustic system (RAS) is designed for comprehensive investigation of thermoelastic (TE), thermophysical (TP) and thermodynamic (TD) characteristics of structural materials. It operation is based on radiation-acoustic method, which includes probing of investigated materials by pulsed electron beam and registration the exited thermo acoustic stress. The hardware includes a CAMAC crate, an IBM PC computer, a set of sensors, a strobe analog-digital converter, a commutators of analog signals, and drivers of physical parameters. The system allows to process thermo acoustic signals generated in beam-target interaction and to extract information about phase state, TE-, TP-, and TD characteristics of the target materials. The system was used for simultaneous measuring of phase state, TE-, TP-, and TD characteristics and for investigation of kinetics of structural phase transitions in multifunctional materials such as materials with the shape memory effect (CuAlNi, TiNi, TiNiFe, TiNiCu), rare-earth metals (Dy, Gd), high-temperature superconductors YBaCuO, piezoelectric crystals (TiBa, ZrTiPb-ceramics), polymers (PMMA, PTFE, PE) etc

  19. Controlling an acoustic wave with a cylindrically-symmetric gradient-index system

    International Nuclear Information System (INIS)

    Zhang Zhe; Li Rui-Qi; Liang Bin; Zou Xin-Ye; Cheng Jian-Chun

    2015-01-01

    We present a detailed theoretical description of wave propagation in an acoustic gradient-index system with cylindrical symmetry and demonstrate its potential to numerically control acoustic waves in different ways. The trajectory of an acoustic wave within the system is derived by employing the theory of geometric acoustics, and the validity of the theoretical descriptions is verified numerically by using the finite element method simulation. The results show that by tailoring the distribution function of the refractive index, the proposed system can yield a tunable manipulation of acoustic waves, such as acoustic bending, trapping, and absorbing. (paper)

  20. Highly Localized Acoustic Streaming and Size-Selective Submicrometer Particle Concentration Using High Frequency Microscale Focused Acoustic Fields.

    Science.gov (United States)

    Collins, David J; Ma, Zhichao; Ai, Ye

    2016-05-17

    Concentration and separation of particles and biological specimens are fundamental functions of micro/nanofluidic systems. Acoustic streaming is an effective and biocompatible way to create rapid microscale fluid motion and induce particle capture, though the >100 MHz frequencies required to directly generate acoustic body forces on the microscale have traditionally been difficult to generate and localize in a way that is amenable to efficient generation of streaming. Moreover, acoustic, hydrodynamic, and electrical forces as typically applied have difficulty manipulating specimens in the submicrometer regime. In this work, we introduce highly focused traveling surface acoustic waves (SAW) at high frequencies between 193 and 636 MHz for efficient and highly localized production of acoustic streaming vortices on microfluidic length scales. Concentration occurs via a novel mechanism, whereby the combined acoustic radiation and streaming field results in size-selective aggregation in fluid streamlines in the vicinity of a high-amplitude acoustic beam, as opposed to previous acoustic radiation induced particle concentration where objects typically migrate toward minimum pressure locations. Though the acoustic streaming is induced by a traveling wave, we are able to manipulate particles an order of magnitude smaller than possible using the traveling wave force alone. We experimentally and theoretically examine the range of particle sizes that can be captured in fluid streamlines using this technique, with rapid particle concentration demonstrated down to 300 nm diameters. We also demonstrate that locations of trapping and concentration are size-dependent, which is attributed to the combined effects of the acoustic streaming and acoustic forces.

  1. Response of a thermal barrier system to acoustic excitation in a gas turbine nuclear reactor

    International Nuclear Information System (INIS)

    Betts, W.S. Jr.; Blevins, R.D.

    1980-11-01

    A gas turbine located within a High-Temperature Gas-Cooled Reactor (HTGR) induces high acoustic sound pressure levels into the primary coolant (helium). This acoustic loading induces high cycle fatigue stresses which may control the design of the thermal barrier system. This study examines the dynamic response of a thermal barrier configuration consisting of a fibrous insulation compressed against the reactor vessel by a coverplate which is held in position by a central attachment fixture. The results of dynamic vibration analyses indicate the effect of the plate size and curvature and the attachment size on the response of the thermal barrier

  2. Impact source location on composite CNG storage tank using acoustic emission energy based signal mapping method

    Energy Technology Data Exchange (ETDEWEB)

    Han, Byeong Hee; Yoon, Dong Jin; Park, Chun Soo [Korea Research Institute of Standards and Science, Center for Safety Measurement, Daejeon (Korea, Republic of); Lee, Young Shin [Dept. of Mechanical Design Engineering, Chungnam National University, Daejeon (Korea, Republic of)

    2016-10-15

    Acoustic emission (AE) is one of the most powerful techniques for detecting damages and identify damage location during operations. However, in case of the source location technique, there is some limitation in conventional AE technology, because it strongly depends on wave speed in the corresponding structures having heterogeneous composite materials. A compressed natural gas(CNG) pressure vessel is usually made of carbon fiber composite outside of vessel for the purpose of strengthening. In this type of composite material, locating impact damage sources exactly using conventional time arrival method is difficult. To overcome this limitation, this study applied the previously developed Contour D/B map technique to four types of CNG storage tanks to identify the source location of damages caused by external shock. The results of the identification of the source location for different types were compared.

  3. Potential of acoustic monitoring for safety assessment of primary system

    International Nuclear Information System (INIS)

    Olma, B.J.

    1997-01-01

    Safety assessment of the primary system and its components with respect to their mechanical integrity is increasingly supported by acoustic signature analysis during power operation of the plants. Acoustic signals of Loose Parts Monitoring System sensors are continuously monitored by dedicated digital systems for signal bursts associated with metallic impacts. Several years of ISTec/GRS experience and the practical use of its digital systems MEDEA and RAMSES have shown that acoustic monitoring is very successful for detecting component failures at an early stage. Advanced powerful tools for classification and acoustic evaluation of burst signals have recently been realized. The paper presents diagnosis experiences of BWR's and PWR's safety assessment. (author). 7 refs, 8 figs

  4. Acoustic tweezing of particles using decaying opposing travelling surface acoustic waves (DOTSAW).

    Science.gov (United States)

    Ng, Jia Wei; Devendran, Citsabehsan; Neild, Adrian

    2017-10-11

    Surface acoustic waves offer a versatile and biocompatible method of manipulating the location of suspended particles or cells within microfluidic systems. The most common approach uses the interference of identical frequency, counter propagating travelling waves to generate a standing surface acoustic wave, in which particles migrate a distance less than half the acoustic wavelength to their nearest pressure node. The result is the formation of a periodic pattern of particles. Subsequent displacement of this pattern, the prerequisite for tweezing, can be achieved by translation of the standing wave, and with it the pressure nodes; this requires changing either the frequency of the pair of waves, or their relative phase. Here, in contrast, we examine the use of two counterpropagating traveling waves of different frequency. The non-linearity of the acoustic forces used to manipulate particles, means that a small frequency difference between the two waves creates a substantially different force field, which offers significant advantages. Firstly, this approach creates a much longer range force field, in which migration takes place across multiple wavelengths, and causes particles to be gathered together in a single trapping site. Secondly, the location of this single trapping site can be controlled by the relative amplitude of the two waves, requiring simply an attenuation of one of the electrical drive signals. Using this approach, we show that by controlling the powers of the opposing incoherent waves, 5 μm particles can be migrated laterally across a fluid flow to defined locations with an accuracy of ±10 μm.

  5. Control of low-frequency noise for piping systems via the design of coupled band gap of acoustic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yanfei [College of Power Engineering, Naval University of Engineering, Wuhan, 430033 (China); Shen, Huijie, E-mail: shj588@163.com [College of Power Engineering, Naval University of Engineering, Wuhan, 430033 (China); Zhang, Linke [School of Energy and Power Engineering, Wuhan University of Technology, Wuhan, 430063 (China); Su, Yongsheng, E-mail: suyongsheng1981@163.com [College of Power Engineering, Naval University of Engineering, Wuhan, 430033 (China); Yu, Dianlong [Key Laboratory of Science and Technology on Integrated Logistics Support, National University of Defense Technology, Changsha 410073 (China)

    2016-07-01

    Acoustic wave propagation and sound transmission in a metamaterial-based piping system with Helmholtz resonator (HR) attached periodically are studied. A transfer matrix method is developed to conduct the investigation. Calculational results show that the introduction of periodic HRs in the piping system could generate a band gap (BG) near the resonant frequency of the HR, such that the bandwidth and the attenuation effect of HR improved notably. Bragg type gaps are also exist in the system due to the systematic periodicity. By plotting the BG as functions of HR parameters, the effect of resonator parameters on the BG behavior, including bandwidth, location and attenuation performance, etc., is examined. It is found that Bragg-type gap would interplay with the resonant-type gap under some special situations, thereby giving rise to a super-wide coupled gap. Further, explicit formulation for BG exact coupling is extracted and some key parameters on modulating the width and the attenuation coefficient of coupled gaps are investigated. The coupled gap can be located to any frequency range as one concerned, thus rendering the low-frequency noise control feasible in a broad band range. - Highlights: • A metamaterial-type pipe system with Bragg and resonant acoustic gaps. • A low-frequency acoustic coupled gap. • Exact coupling condition for Bragg and resonant gaps. • Effects of resonant parameters on coupled gaps.

  6. Nano-optomechanical system based on microwave frequency surface acoustic waves

    Science.gov (United States)

    Tadesse, Semere Ayalew

    Cavity optomechnics studies the interaction of cavity confined photons with mechanical motion. The emergence of sophisticated nanofabrication technology has led to experimental demonstrations of a wide range of novel optomechanical systems that exhibit strong optomechanical coupling and allow exploration of interesting physical phenomena. Many of the studies reported so far are focused on interaction of photons with localized mechanical modes. For my doctoral research, I did experimental investigations to extend this study to propagating phonons. I used surface travelling acoustic waves as the mechanical element of my optomechanical system. The optical cavities constitute an optical racetrack resonator and photonic crystal nanocavity. This dissertation discusses implementation of this surface acoustic wave based optomechanical system and experimental demonstrations of important consequences of the optomechanical coupling. The discussion focuses on three important achievements of the research. First, microwave frequency surface acoustic wave transducers were co-integrated with an optical racetrack resonator on a piezoelectric aluminum nitride film deposited on an oxidized silicon substrate. Acousto-optic modulation of the resonance modes at above 10 GHz with the acoustic wavelength significantly below the optical wavelength was achieved. The phase and modal matching conditions in this paradigm were investigated for efficient optmechanical coupling. Second, the optomechanical coupling was pushed further into the sideband resolved regime by integrating the high frequency surface acoustic wave transducers with a photonic crystal nanocavity. This device was used to demonstrate optomecahnically induced transparency and absorption, one of the interesting consequences of cavity optomechanics. Phase coherent interaction of the acoustic wave with multiple nanocavities was also explored. In a related experiment, the photonic crystal nanoscavity was placed inside an acoustic

  7. Ares I Scale Model Acoustic Test Instrumentation for Acoustic and Pressure Measurements

    Science.gov (United States)

    Vargas, Magda B.; Counter, Douglas

    2011-01-01

    Ares I Scale Model Acoustic Test (ASMAT) is a 5% scale model test of the Ares I vehicle, launch pad and support structures conducted at MSFC to verify acoustic and ignition environments and evaluate water suppression systems Test design considerations 5% measurements must be scaled to full scale requiring high frequency measurements Users had different frequencies of interest Acoustics: 200 - 2,000 Hz full scale equals 4,000 - 40,000 Hz model scale Ignition Transient: 0 - 100 Hz full scale equals 0 - 2,000 Hz model scale Environment exposure Weather exposure: heat, humidity, thunderstorms, rain, cold and snow Test environments: Plume impingement heat and pressure, and water deluge impingement Several types of sensors were used to measure the environments Different instrument mounts were used according to the location and exposure to the environment This presentation addresses the observed effects of the selected sensors and mount design on the acoustic and pressure measurements

  8. Pre-service Acoustic Emission Testing for Metal Pressure Vessel

    International Nuclear Information System (INIS)

    Lee, Jong O; Yoon, Woon Ha; Lee, Tae Hee; Lee, Jong Kyu

    2003-01-01

    The field application of acoustic emission(AE) testing for brand-new metal pressure vessel were performed. We will introduce the test procedure for acoustic emission test such as instrument check distance between sensors, sensor location, whole system calibration, pressurization sequence, noise reduction and evaluation. The data of acoustic emission test contain many noise signal, these noise can be reduced by time filtering which based on the description of observation during AE test

  9. Acoustic--nuclear permeability logging system

    International Nuclear Information System (INIS)

    Dowling, D.J.; Arnold, D.M.

    1978-01-01

    A down hole logging tool featuring a neutron generator, an acoustic disturbance generator, and a radiation detection system is described. An array of acoustic magnetostriction transducers is arranged about the target of a neutron accelerator. Two gamma ray sensors are separated from the accelerator target by shielding. According to the method of the invention, the underground fluid at the level of a formation is bombarded by neutrons which react with oxygen in the fluid to produce unstable nitrogen 16 particles according to the reaction 16 O(n,p) 16 N. Acoustic pulses are communicated to the fluid, and are incident on the boundary of the borehole at the formation. The resulting net flow of fluid across the boundary is determined from radiation detection measurements of the decaying 16 N particles in the fluid. A measure of the permeability of the formation is obtained from the determination of net fluid flow across the boundary

  10. Experience with digital acoustic monitoring systems for PWRs and BWRs

    International Nuclear Information System (INIS)

    Olma, B.J.

    1998-01-01

    Substantial progress could be reached both in system technics and in application of digital acoustic monitoring systems for assessing mechanical integrity of reactor primary systems. For the surveillance of PWRs and BWRs during power operation of the plants, acoustic signals of Loose Parts Monitoring System sensors are continuously monitored for signal bursts associated with metallic impacts. ISTec/GRS experience with its digital systems MEDEA and RAMSES has shown that acoustic signature analysis is very successful for detecting component failures at an early stage. Methods for trending and classification of digital burst signals are shown, experience with their practical use will be presented. (author)

  11. Acoustic Signals and Systems

    DEFF Research Database (Denmark)

    2008-01-01

    The Handbook of Signal Processing in Acoustics will compile the techniques and applications of signal processing as they are used in the many varied areas of Acoustics. The Handbook will emphasize the interdisciplinary nature of signal processing in acoustics. Each Section of the Handbook...... will present topics on signal processing which are important in a specific area of acoustics. These will be of interest to specialists in these areas because they will be presented from their technical perspective, rather than a generic engineering approach to signal processing. Non-specialists, or specialists...... from different areas, will find the self-contained chapters accessible and will be interested in the similarities and differences between the approaches and techniques used in different areas of acoustics....

  12. Microfluidic ultrasonic particle separators with engineered node locations and geometries

    Science.gov (United States)

    Rose, Klint A.; Fisher, Karl A.; Wajda, Douglas A.; Mariella, Jr., Raymond P.; Bailey, Christopher; Dehlinger, Dietrich; Shusteff, Maxim; Jung, Byoungsok; Ness, Kevin D.

    2016-04-26

    An ultrasonic microfluidic system includes a separation channel for conveying a sample fluid containing small particles and large particles, flowing substantially parallel, adjacent to a recovery fluid, with which it is in contact. An acoustic transducer produces an ultrasound standing wave, that generates a pressure field having at least one node of minimum pressure amplitude. An acoustic extension structure is located proximate to said separation channel for positioning said acoustic node off center in said acoustic area and concentrating the large particles in said recovery fluid stream.

  13. Acoustic monitoring systems tests at Indian Point Unit 1. Final report

    International Nuclear Information System (INIS)

    Smith, J.R.; Rao, G.V.; Craig, J.

    1979-12-01

    This report describes the results of a program to test acoustic monitoring systems on Indian Point Unit No. 1 under actual plant operating conditions, less the reactor core. The two types of systems evaluated were the monitoring of acoustic emissions generated by growing flaws and the monitoring of acoustic signals from leaks

  14. Ares I Scale Model Acoustic Tests Instrumentation for Acoustic and Pressure Measurements

    Science.gov (United States)

    Vargas, Magda B.; Counter, Douglas D.

    2011-01-01

    The Ares I Scale Model Acoustic Test (ASMAT) was a development test performed at the Marshall Space Flight Center (MSFC) East Test Area (ETA) Test Stand 116. The test article included a 5% scale Ares I vehicle model and tower mounted on the Mobile Launcher. Acoustic and pressure data were measured by approximately 200 instruments located throughout the test article. There were four primary ASMAT instrument suites: ignition overpressure (IOP), lift-off acoustics (LOA), ground acoustics (GA), and spatial correlation (SC). Each instrumentation suite incorporated different sensor models which were selected based upon measurement requirements. These requirements included the type of measurement, exposure to the environment, instrumentation check-outs and data acquisition. The sensors were attached to the test article using different mounts and brackets dependent upon the location of the sensor. This presentation addresses the observed effect of the sensors and mounts on the acoustic and pressure measurements.

  15. Perancangan Prototipe Receiver Beacon Black Box Locator Acoustic 37,5 kHz Pingers

    Directory of Open Access Journals (Sweden)

    RUSTAMAJI RUSTAMAJI

    2016-01-01

    When an aircraft caught in an accident and crashes into the water, its location can be detected using a device called a receiver beacon black box locator acoustic (pingers receiver. The pingers receiver functioned as a reciever signal with 37,5 kHz ± 1 kHz frequency from trnasmitter pingers or Underwater Locator Beacon (ULB which is on air plane black blox. In this research made design pingers receiver composed of a series of  Band Pass Filter (BPF, envelope detector, audio amplifier, and loud speaker. The signal of 37,5 kHz ± 1 kHz  frequency sent by pingers transmitter will bereceived by pingers receiver, after which the signal will be processed by the Band Pass Filter (BPF circuit before being detected by envelope detector for take back the signal information which like pulse signal with 10ms width and 1 second interval as pingers signal tha can  be to  be heard by human ear. Based on the  design that  was made, the signal ouput generated by the prototype has a 14 ms width with 1 second interval. Keywords: pingers receiver, band pass filter (BPF, envelope detector, loud speaker.

  16. Acoustic monitoring to support plant life extension at Sellafield

    International Nuclear Information System (INIS)

    Wit, M. de; Hovhanessian, G.

    2015-01-01

    Tensioned steel wires are widely used in civil engineering structures. They can, however, be vulnerable to corrosion. To reduce the probability of corrosion, sophisticated protection systems are used. Extensive inspection and maintenance regimes are also able to be implemented to confirm that the design strength is available over the lifetime of the wires. These regimes include tests to confirm the condition of post-tensioning cables or stay cables, which can verify the overall performance of the structure. This paper presents a technology to detect and locate wire failures in tensioned cables for use on a wide variety of pre-stressed or post tensioned structures, where they have increased confidence in the structures and reduced maintenance costs. This methodology is the continuous acoustic monitoring technology which uses distinctive acoustic characteristics of wire breaks to separate them from other acoustic activity on the structure. With a combination of instrumentation, data acquisition and data management, it is possible to identify a wire break event, as well as to locate the position and time of the failure. Over 10 years' experience of acoustic monitoring for this application with several independent and blind tests, shows that even in noisy environments the acoustic monitoring method is able to identify and locate wire breaks in fully grouted and partially grouted tendons, stay cables and suspension cables. The design (number of sensors and location) is very important to be sure to cover all wires in the structure. This paper explains the principles of the systems and shows them in practice on a case study of a project in a pre-stressed roof structure of an active tank farm at Sellafield site

  17. Preliminary characterization of a one-axis acoustic system. [acoustic levitation for space processing

    Science.gov (United States)

    Oran, W. A.; Reiss, D. A.; Berge, L. H.; Parker, H. W.

    1979-01-01

    The acoustic fields and levitation forces produced along the axis of a single-axis resonance system were measured. The system consisted of a St. Clair generator and a planar reflector. The levitation force was measured for bodies of various sizes and geometries (i.e., spheres, cylinders, and discs). The force was found to be roughly proportional to the volume of the body until the characteristic body radius reaches approximately 2/k (k = wave number). The acoustic pressures along the axis were modeled using Huygens principle and a method of imaging to approximate multiple reflections. The modeled pressures were found to be in reasonable agreement with those measured with a calibrated microphone.

  18. Acoustic control system BN-350. Explanatory note

    International Nuclear Information System (INIS)

    1982-02-01

    A description of the acoustic system developed to control boiling in the active zone of the BN 350 reactor is given together with the corresponding technical characteristics. The results of experiments and calculations which confirm the validity of the solutions adopted are discussed. Theoretical calculations on the boiling process in the duct are reported together with details on the fast diagnostic system. A means for localizing the onset of boiling is also given, possible error being taken into consideration. The special features of the passive acoustic diagnostic method used to study boiling are described and schemas of the anciliary equipment presented [fr

  19. Preliminary Development of Online Monitoring Acoustic Emission System for the Integrity of Research Reactor Components

    Science.gov (United States)

    Bakhri, S.; Sumarno, E.; Himawan, R.; Akbar, T. Y.; Subekti, M.; Sunaryo, G. R.

    2018-02-01

    Three research reactors owned by BATAN have been more than 25 years. Aging of (Structure, System and Component) SSC which is mainly related to mechanical causes become the most important issue for the sustainability and safety operation. Acoustic Emission (AE) is one of the appropriate and recommended methods by the IAEA for inspection as well as at the same time for the monitoring of mechanical SSC related. However, the advantages of AE method in detecting the acoustic emission both for the inspection and the online monitoring require a relatively complex measurement system including hardware software system for the signal detection and analysis purposes. Therefore, aim of this work was to develop an AE system based on an embedded system which capable for doing both the online monitoring and inspection of the research reactor’s integrity structure. An embedded system was selected due to the possibility to install the equipment on the field in extreme environmental condition with capability to store, analyses, and send the required information for further maintenance and operation. The research was done by designing the embedded system based on the Field Programmable Gate Array (FPGA) platform, because of their execution speed and system reconfigurable opportunities. The AE embedded system is then tested to identify the AE source location and AE characteristic under tensile material testing. The developed system successfully acquire the AE elastic waveform and determine the parameter-based analysis such as the amplitude, peak, duration, rise time, counts and the average frequency both for the source location test and the tensile test.

  20. Channel coding for underwater acoustic single-carrier CDMA communication system

    Science.gov (United States)

    Liu, Lanjun; Zhang, Yonglei; Zhang, Pengcheng; Zhou, Lin; Niu, Jiong

    2017-01-01

    CDMA is an effective multiple access protocol for underwater acoustic networks, and channel coding can effectively reduce the bit error rate (BER) of the underwater acoustic communication system. For the requirements of underwater acoustic mobile networks based on CDMA, an underwater acoustic single-carrier CDMA communication system (UWA/SCCDMA) based on the direct-sequence spread spectrum is proposed, and its channel coding scheme is studied based on convolution, RA, Turbo and LDPC coding respectively. The implementation steps of the Viterbi algorithm of convolutional coding, BP and minimum sum algorithms of RA coding, Log-MAP and SOVA algorithms of Turbo coding, and sum-product algorithm of LDPC coding are given. An UWA/SCCDMA simulation system based on Matlab is designed. Simulation results show that the UWA/SCCDMA based on RA, Turbo and LDPC coding have good performance such that the communication BER is all less than 10-6 in the underwater acoustic channel with low signal to noise ratio (SNR) from -12 dB to -10dB, which is about 2 orders of magnitude lower than that of the convolutional coding. The system based on Turbo coding with Log-MAP algorithm has the best performance.

  1. Tethys Acoustic Metadata Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Tethys database houses the metadata associated with the acoustic data collection efforts by the Passive Acoustic Group. These metadata include dates, locations...

  2. Quasi-static acoustic tweezing thromboelastometry.

    Science.gov (United States)

    Holt, R G; Luo, D; Gruver, N; Khismatullin, D B

    2017-07-01

    Essentials Blood coagulation measurement during contact with an artificial surface leads to unreliable data. Acoustic tweezing thromboelastometry is a novel non-contact method for coagulation monitoring. This method detects differences in the blood coagulation state within 10 min. Coagulation data were obtained using a much smaller sample volume (4 μL) than currently used. Background Thromboelastography is widely used as a tool to assess the coagulation status of critical care patients. It allows observation of changes in material properties of whole blood, beginning with early stages of clot formation and ending with clot lysis. However, the contact activation of the coagulation cascade at surfaces of thromboelastographic systems leads to inherent variability and unreliability in predicting bleeding or thrombosis risks. Objectives To develop acoustic tweezing thromboelastometry as a non-contact method for perioperative assessment of blood coagulation. Methods Acoustic tweezing is used to levitate microliter drops of biopolymer and human blood samples. By quasi-statically changing the acoustic pressure we control the sample drop location and deformation. Sample size, deformation and location are determined by digital imaging at each pressure. Results Simple Newtonian liquid solutions maintain a constant, reversible location vs. deformation curve. In contrast, the location/deformation curves for gelatin, alginate, whole blood and blood plasma uniquely change as the samples solidify. Increasing elasticity causes the sample to deform less, leading to steeper stress/strain curves. By extracting a linear regime slope, we show that whole blood or blood plasma exhibits a unique slope profile as it begins to clot. By exposing blood samples to pro- or antithrombotic agents, the slope profile changes, allowing detection of hyper- or hypocoagulable states. Conclusions We demonstrate that quasi-static acoustic tweezing can yield information about clotting onset, maturation

  3. NEMO-SMO acoustic array: A deep-sea test of a novel acoustic positioning system for a km3-scale underwater neutrino telescope

    Science.gov (United States)

    Viola, S.; Ardid, M.; Bertin, V.; Enzenhöfer, A.; Keller, P.; Lahmann, R.; Larosa, G.; Llorens, C. D.; NEMO Collaboration; SMO Collaboration

    2013-10-01

    Within the activities of the NEMO project, the installation of a 8-floors tower (NEMO-Phase II) at a depth of 3500 m is foreseen in 2012. The tower will be installed about 80 km off-shore Capo Passero, in Sicily. On board the NEMO tower, an array of 18 acoustic sensors will be installed, permitting acoustic detection of biological sources, studies for acoustic neutrino detection and primarily acoustic positioning of the underwater structures. For the latter purpose, the sensors register acoustic signals emitted by five acoustic beacons anchored on the sea-floor. The data acquisition system of the acoustic sensors is fully integrated with the detector data transport system and is based on an “all data to shore” philosophy. Signals coming from hydrophones are continuously sampled underwater at 192 kHz/24 bit and transmitted to shore through an electro-optical cable for real-time analysis. A novel technology for underwater GPS time-stamping of data has been implemented and tested. The operation of the acoustic array will permit long-term test of sensors and electronics technologies that are proposed for the acoustic positioning system of KM3NeT.

  4. Cave acoustics in prehistory: Exploring the association of Palaeolithic visual motifs and acoustic response.

    Science.gov (United States)

    Fazenda, Bruno; Scarre, Chris; Till, Rupert; Pasalodos, Raquel Jiménez; Guerra, Manuel Rojo; Tejedor, Cristina; Peredo, Roberto Ontañón; Watson, Aaron; Wyatt, Simon; Benito, Carlos García; Drinkall, Helen; Foulds, Frederick

    2017-09-01

    During the 1980 s, acoustic studies of Upper Palaeolithic imagery in French caves-using the technology then available-suggested a relationship between acoustic response and the location of visual motifs. This paper presents an investigation, using modern acoustic measurement techniques, into such relationships within the caves of La Garma, Las Chimeneas, La Pasiega, El Castillo, and Tito Bustillo in Northern Spain. It addresses methodological issues concerning acoustic measurement at enclosed archaeological sites and outlines a general framework for extraction of acoustic features that may be used to support archaeological hypotheses. The analysis explores possible associations between the position of visual motifs (which may be up to 40 000 yrs old) and localized acoustic responses. Results suggest that motifs, in general, and lines and dots, in particular, are statistically more likely to be found in places where reverberation is moderate and where the low frequency acoustic response has evidence of resonant behavior. The work presented suggests that an association of the location of Palaeolithic motifs with acoustic features is a statistically weak but tenable hypothesis, and that an appreciation of sound could have influenced behavior among Palaeolithic societies of this region.

  5. Real-time system for studies of the effects of acoustic feedback on animal vocalizations.

    Directory of Open Access Journals (Sweden)

    Mike eSkocik

    2013-01-01

    Full Text Available Studies of behavioral and neural responses to distorted auditory feedback can help shed light on the neural mechanisms of animal vocalizations. We describe an apparatus for generating real-time acoustic feedback. The system can very rapidly detect acoustic features in a song and output acoustic signals if the detected features match the desired acoustic template. The system uses spectrogram-based detection of acoustic elements. It is low-cost and can be programmed for a variety of behavioral experiments requiring acoustic feedback or neural stimulation. We use the system to study the effects of acoustic feedback on birds' vocalizations and demonstrate that such an acoustic feedback can cause both immediate and long-term changes to birds’ songs.

  6. Integration of acoustic emission systems within Integri-TechTM analysis system for structural health monitoring of pressurised engineering plant

    International Nuclear Information System (INIS)

    Ghouri, A A; Galbraith, Walter; Pierce, S Gareth; Gachagan, Anthony; Rafferty, Steven; Pickwell, Andy

    2015-01-01

    The aim of this Acoustic Emission (AE) based Structural Health Monitoring project is to enable accurate location of AE sources in pressurised engineering plant and to use AE source location data to establish defect locations for use within Integri-Tech TM ; a finite element based analysis, monitoring and fitness for service assessment system. Integri-Tech TM is a windows based system which carries out combined analysis and assessment providing fatigue life and remnant life calculations and inspection priorities presenting the results in an accessible web portal format. The software uses finite element stress models created in the companion software Model Wizard. The AE monitoring system that has been developed can be used with an array of up to four AE broad band sensor channels with associated signal processing. Using a flexible approach in MATLAB, the authors have developed algorithms which were used for analysing the received AE signals to extract information about the nature and location of the source. The ability to carry out source location and possibly perform real time monitoring (detecting cracking as it occurs) is attractive feature of the AE system developed for this project. The time of arrival (TOA) data was used by Integri-Tech TM software to calculate source location using its own built-in algorithm, and this was verified independently using a MATLAB approach. (paper)

  7. A Non-Intrusive GMA Welding Process Quality Monitoring System Using Acoustic Sensing.

    Science.gov (United States)

    Cayo, Eber Huanca; Alfaro, Sadek Crisostomo Absi

    2009-01-01

    Most of the inspection methods used for detection and localization of welding disturbances are based on the evaluation of some direct measurements of welding parameters. This direct measurement requires an insertion of sensors during the welding process which could somehow alter the behavior of the metallic transference. An inspection method that evaluates the GMA welding process evolution using a non-intrusive process sensing would allow not only the identification of disturbances during welding runs and thus reduce inspection time, but would also reduce the interference on the process caused by the direct sensing. In this paper a nonintrusive method for weld disturbance detection and localization for weld quality evaluation is demonstrated. The system is based on the acoustic sensing of the welding electrical arc. During repetitive tests in welds without disturbances, the stability acoustic parameters were calculated and used as comparison references for the detection and location of disturbances during the weld runs.

  8. Study on flow-induced acoustic resonance in symmetrically located side-branches using dynamic PIV technique

    International Nuclear Information System (INIS)

    Li, Yanrong; Inagaki, Terumi; Nishi, Yasuyuki; Someya, Satoshi; Okamoto, Koji

    2014-01-01

    Flow-induced acoustic resonance in a piping system containing closed coaxial side-branches was investigated experimentally. Resonance characteristics of the piping system were examined by a microphone. The results revealed that the resonance frequencies of the shear layer instability were locked in corresponding to the natural frequencies of the side-branches. Phase-averaged velocity fields were obtained two-dimensionally in the junction of coaxial side-branches by dynamic particle image velocimetry (PIV), while the acoustic resonance was induced at the first and second hydrodynamic modes. Patterns of jet correspond to two hydrodynamic modes were derived from the phase-averaged velocity fields. The dynamic PIV can acquire time-series velocity fluctuations, then, two-dimensional phase delay maps under resonance and off-resonance conditions in the junction of coaxial side-branches were obtained. Experimental results show that the proposed phase delay map method costs less experiment and computation time and achieves a better accuracy and repetition than the phase-locking technique. In addition, the phase delay map method can obtain phase difference under the different frequency components. This is important when two different acoustic modes were induced in one experimental condition. (author)

  9. Acoustic fMRI noise : Linear time-invariant system model

    NARCIS (Netherlands)

    Sierra, Carlos V. Rizzo; Versluis, Maarten J.; Hoogduin, Johannes M.; Duifhuis, Hendrikus (Diek)

    Functional magnetic resonance imaging (fMRI) enables sites of brain activation to be localized in human subjects. For auditory system studies, however, the acoustic noise generated by the scanner tends to interfere with the assessments of this activation. Understanding and modeling fMRI acoustic

  10. An acoustic system for autonomous navigation and tracking of marine fauna

    KAUST Repository

    De la Torre, Pedro; Salama, Khaled N.; Berumen, Michael L.

    2014-01-01

    A marine acoustic system for underwater target tracking is described. This system is part of the Integrated Satellite and Acoustic Telemetry (iSAT) project to study marine fauna. It is a microcontroller-based underwater projector and receiver. A

  11. Auditory modelling for assessing room acoustics

    NARCIS (Netherlands)

    Van Dorp Schuitman, J.

    2011-01-01

    The acoustics of a concert hall, or any other room, are generally assessed by measuring room impulse responses for one or multiple source and receiver location(s). From these responses, objective parameters can be determined that should be related to various perceptual attributes of room acoustics.

  12. Development of acoustic leak detection system in PNC

    International Nuclear Information System (INIS)

    Tanabe, H.; Kuroha, M.

    1990-01-01

    The development of an acoustic leak detector is under way at PNC as a detection system that has potential of quick response and high reliability for larger steam generators of future LMFBR plants. The studies have two aspects, i.e., an acoustic wave analysis in various sodium-water reactions and a background noise (BGN) analysis in a sodium-heated 50MWt steam generator (50MWGS). In the former analysis, wave profiles of the sodium-water reaction sound were analyzed and compared with those of inert gas injection sound. The comparison revealed that there were no wave profiles specific to a sodium-water reaction sound. The latter clarified that major acoustic sources in the steam generator were sodium flow and steam generation/flow and that the water leak rate at which a noise level was comparable with that of the background noise was about 0.5 g/sec. in the evaporator of 50MWSG. The estimation of acceleration levels of BGN and leak sounds in other plants reveals that an intermediate leak is detectable in the Monju evaporator with a present acoustic detection system. (author). 2 refs, 9 figs

  13. Active Hearing Mechanisms Inspire Adaptive Amplification in an Acoustic Sensor System.

    Science.gov (United States)

    Guerreiro, Jose; Reid, Andrew; Jackson, Joseph C; Windmill, James F C

    2018-06-01

    Over many millions of years of evolution, nature has developed some of the most adaptable sensors and sensory systems possible, capable of sensing, conditioning and processing signals in a very power- and size-effective manner. By looking into biological sensors and systems as a source of inspiration, this paper presents the study of a bioinspired concept of signal processing at the sensor level. By exploiting a feedback control mechanism between a front-end acoustic receiver and back-end neuronal based computation, a nonlinear amplification with hysteretic behavior is created. Moreover, the transient response of the front-end acoustic receiver can also be controlled and enhanced. A theoretical model is proposed and the concept is prototyped experimentally through an embedded system setup that can provide dynamic adaptations of a sensory system comprising a MEMS microphone placed in a closed-loop feedback system. It faithfully mimics the mosquito's active hearing response as a function of the input sound intensity. This is an adaptive acoustic sensor system concept that can be exploited by sensor and system designers within acoustics and ultrasonic engineering fields.

  14. Design of acoustic emission monitoring system based on VC++

    Science.gov (United States)

    Yu, Yang; He, Wei

    2015-12-01

    At present, a lot of companies at home and abroad have researched and produced a batch of specialized monitoring instruments for acoustic emission (AE). Most of them cost highly and the system function exists in less stable and less portability for the testing environment and transmission distance and other aspects. Depending on the research background and the status quo, a dual channel intelligent acoustic emission monitoring system was designed based on Microsoft Foundation Classes in Visual Studio C++ to solve some of the problems in the acoustic emission research and meet the needs of actual monitoring task. It contains several modules such as main module, acquisition module, signal parameters setting module and so on. It could give out corrosion AE waveform and signal parameters results according to the main menu selected parameters. So the needed information could be extracted from the experiments datum to solve the problem deeply. This soft system is the important part of AE detection g system.

  15. Acoustic detection for water/steam leak from a tube of LMFBR steam generator

    International Nuclear Information System (INIS)

    Sonoda, Masataka; Shindo, Yoshihisa

    1989-01-01

    Acoustic leak detector is useful for detecting more quickly intermediate leak than the existing hydrogen detector and is available for identification of leak location on the accident of water/steam leak from a tube of LMFBR steam generator. This paper presents the overview of HALD (High frequency Acoustics Leak Detection) system, which is more sensitive for leak detection and lower cost of equipment for identification of leak location than a low frequency type detector. (author)

  16. Wireless microwave acoustic sensor system for condition monitoring in power plant environments

    Energy Technology Data Exchange (ETDEWEB)

    Pereira da Cunha, Mauricio [Univ. of Maine, Orno, ME (United States)

    2017-03-30

    This project successfully demonstrated novel wireless microwave acoustic temperature and pressure sensors that can be embedded into equipment and structures located in fossil fuel power plant environments to monitor the condition of components such as steam headers, re-heat lines, water walls, burner tubes, and power turbines. The wireless microwave acoustic sensor technology researched and developed through a collaborative partnership between the University of Maine and Environetix Technologies Corporation can provide a revolutionary impact in the power industry since it is anticipated that the wireless sensors will deliver reliable real-time sensing information in harsh power plant conditions that involve temperatures up to 1100oC and pressures up to 750 psi. The work involved the research and development of novel high temperature harsh environment thin film electrodes, piezoelectric smart microwave acoustic sensing elements, sensor encapsulation materials that were engineered to function over long times up to 1100oC, and a radio-frequency (RF) wireless interrogation electronics unit that are located both inside and outside the high temperature harsh environment. The UMaine / Environetix team have interacted with diverse power plant facilities, and identified as a testbed a local power generation facility, which burns municipal solid waste (MSW), the Penobscot Energy Recovery Company (PERC), Orrington, Maine. In this facility Environetix / UMaine successfully implemented and tested multiple wireless temperature sensor systems within the harsh-environment of the economizer chamber and at the boiler tubes, transferring the developed technology to the power plant environment to perform real-time sensor monitoring experiments under typical operating conditions, as initially targeted in the project. The wireless microwave acoustic sensor technology developed under this project for power plant applications offers several significant advantages including wireless

  17. Analysis, Design, and Evaluation of Acoustic Feedback Cancellation Systems for Hearing Aids

    DEFF Research Database (Denmark)

    Guo, Meng

    2013-01-01

    Acoustic feedback problems occur when the output loudspeaker signal of an audio system is partly returned to the input microphone via an acoustic coupling through the air. This problem often causes significant performance degradations in applications such as public address systems and hearing aids....... In the worst case, the audio system becomes unstable and howling occurs. In this work, first we analyze a general multiple microphone audio processing system, where a cancellation system using adaptive filters is used to cancel the effect of acoustic feedback. We introduce and derive an accurate approximation...... in acoustic feedback cancellation for hearing aids. It utilizes a probe noise signal which is generated with a specific characteristic so that it can facilitate an unbiased adaptive filter estimation with fast tracking of feedback path variations/changes despite its low signal level. We show in a hearing aid...

  18. Acoustic leak detection development in the USA

    International Nuclear Information System (INIS)

    Greene, D.A.; Malovrh, J.W.; Magee, P.M.

    1984-01-01

    Acoustic monitoring systems that detect and locate a leak of water/steam from a defective tube in an LMFBR steam generator have been developed in the United States. A low frequency (approx. 10 KHz) system was developed by General Electric, and a high frequency (200 to 300 KHz) system by Rockwell International with support from Argonne National Laboratory. A comprehensive base technology program provided absolute signal amplitudes, background noise amplitudes, and signal source-to-detector transfer functions. Field tests of these systems demonstrated an ability to detect and locate simulated leaks under operating and quiescent conditions in an LMFBR steam generator. (author)

  19. Acoustic emission monitoring during hydrotest of a thin wall pressure vessel

    International Nuclear Information System (INIS)

    Fontana, E.; Grugni, G.; Panzani, C.; Pirovano, B.; Possa, G.; Tonolini, F.

    1976-01-01

    Results are presented of the acoustic emission monitoring during hydrotests of a thin wall steel pressure vessel. Location of acoustic sources was based on longitudinal wave front detection. The careful calibration of the three sensors used for acoustic source location was found to be very useful, and allowed an accurate location error analysis. Acoustic emission in the hydrotests was found to be due mainly to stress release in weld seams

  20. Forced synchronization and asynchronous quenching in a thermo-acoustic system

    Science.gov (United States)

    Mondal, Sirshendu; Pawar, Samadhan A.; Sujith, Raman

    2017-11-01

    Forced synchronization, which has been extensively studied in theory and experiments, occurs through two different mechanisms known as phase locking and asynchronous quenching. The latter indicates the suppression of oscillation amplitude. In most practical combustion systems such as gas turbine engines, the main concern is high amplitude pressure oscillations, known as thermo-acoustic instability. Thermo-acoustic instability is undesirable and needs to be suppressed because of its damaging consequences to an engine. In the present study, a systematic experimental investigation of forced synchronization is performed in a prototypical thermo-acoustic system, a Rijke tube, in its limit cycle operation. Further, we show a qualitatively similar behavior using a reduced order model. In the phase locking region, the simultaneous occurrence of synchronization and resonant amplification leads to high amplitude pressure oscillations. However, a reduction in the amplitude of natural oscillations by about 78% of the unforced amplitude is observed when the forcing frequency is far lower than the natural frequency. This shows the possibility of suppression of the oscillation amplitude through asynchronous quenching in thermo-acoustic systems.

  1. Remote erosion and corrosion monitoring of subsea pipelines using acoustic telemetry and wet-mate connector technology

    Energy Technology Data Exchange (ETDEWEB)

    Painter, Howard; Barlow, Stewart [Teledyne ODI, Thousand Oaks, CA (United States); Clarke, Daniel [Teledyne Cormon, Thousand Oaks, CA (United States); Green, Dale [Teledyne Benthos, North Falmouth, MA (United States)

    2009-07-01

    This paper will present a novel approach for monitoring erosion and corrosion using proven sub sea technologies: intrusive erosion and corrosion monitoring, acoustic telemetry and wet-mateable connector technology. Intrusive metal loss based monitoring systems on sub sea pipelines are increasingly being used because of their ability to directly measure erosion and corrosion. These systems are integrated with the sub sea production control system or located close to the platform and hard-wired. However, locations remote from a sub sea control system or platform requires a dedicated communication system and long lengths of cable that can be cost prohibitive to procure and install. The system presented consists of an intrusive erosion or corrosion monitor with pressure and temperature transmitters, a retrievable electronics module with an acoustic modem, a data storage module, and a replaceable power module. Time-stamped erosion and corrosion data can be transmitted via an acoustic link to a surface platform, a vessel of opportunity or to a relaying modem. Acoustic signals can be transmitted up to 6 km from the monitoring location. The power module along with data module and acoustic modem are mounted on the erosion and corrosion module using wet-mateable connectors, allowing retrieval by remotely operated vehicles. The collected data can be used to assess the cumulative erosion and corrosion as well as use the real-time metal loss rate data to correlate with operational parameters. Benefits include optimization of corrosion inhibitor dosage rates, mitigation of damage caused by solids production, and increased flow assurance. (author)

  2. Development and verification of a software tool for the acoustic location of partial discharge in a power transformer

    Directory of Open Access Journals (Sweden)

    Polužanski Vladimir

    2014-01-01

    Full Text Available This paper discusses the development and verification of software tool for determining the location of partial discharge in a power transformer with the acoustic method. Classification and systematization of physical principles and detection methods and tests of partial discharge in power transformers are shown at the beginning of this paper. The most important mathematical models, features, algorithms, and real problems that affect measurement accuracy are highlighted. This paper describes the development and implementation of a software tool for determining the location of partial discharge in a power transformer based on a no iterative mathematical algorithm. Verification and accuracy of measurement are proved both by computer simulation and experimental results available in the literature.

  3. De-Dopplerization of Acoustic Measurements

    Science.gov (United States)

    2017-08-10

    accurate measurement of aircraft location to resample the time signal to account for the compression and expansion of acoustic wavefronts. Correcting...AFRL-RH-WP-TR-2017-0043 DE-DOPPLERIZATION OF ACOUSTIC MEASUREMENTS Frank Mobley, PhD 711 HPW/RHCB Wright-Patterson AFB OH...TITLE AND SUBTITLE DE-DOPPLERIZATION OF ACOUSTIC MEASUREMENTS 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER

  4. Distributed acoustic sensing for pipeline monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Hill, David; McEwen-King, Magnus [OptaSense, QinetiQ Ltd., London (United Kingdom)

    2009-07-01

    Optical fibre is deployed widely across the oil and gas industry. As well as being deployed regularly to provide high bandwidth telecommunications and infrastructure for SCADA it is increasingly being used to sense pressure, temperature and strain along buried pipelines, on subsea pipelines and downhole. In this paper we present results from the latest sensing capability using standard optical fibre to detect acoustic signals along the entire length of a pipeline. In Distributed Acoustic Sensing (DAS) an optical fibre is used for both sensing and telemetry. In this paper we present results from the OptaSense{sup TM} system which has been used to detect third party intervention (TPI) along buried pipelines. In a typical deployment the system is connected to an existing standard single-mode fibre, up to 50km in length, and was used to independently listen to the acoustic / seismic activity at every 10 meter interval. We will show that through the use of advanced array processing of the independent, simultaneously sampled channels it is possible to detect and locate activity within the vicinity of the pipeline and through sophisticated acoustic signal processing to obtain the acoustic signature to classify the type of activity. By combining spare fibre capacity in existing buried fibre optic cables; processing and display techniques commonly found in sonar; and state-of-the-art in fibre-optic distributed acoustic sensing, we will describe the new monitoring capabilities that are available to the pipeline operator. Without the expense of retrofitting sensors to the pipeline, this technology can provide a high performance, rapidly deployable and cost effective method of providing gapless and persistent monitoring of a pipeline. We will show how this approach can be used to detect, classify and locate activity such as; third party interference (including activity indicative of illegal hot tapping); real time tracking of pigs; and leak detection. We will also show how an

  5. Directional radiation pattern in structural-acoustic coupled system

    Science.gov (United States)

    Seo, Hee-Seon; Kim, Yang-Hann

    2005-07-01

    In this paper we demonstrate the possibility of designing a radiator using structural-acoustic interaction by predicting the pressure distribution and radiation pattern of a structural-acoustic coupling system that is composed by a wall and two spaces. If a wall separates spaces, then the wall's role in transporting the acoustic characteristics of the spaces is important. The spaces can be categorized as bounded finite space and unbounded infinite space. The wall considered in this study composes two plates and an opening, and the wall separates one space that is highly reverberant and the other that is unbounded without any reflection. This rather hypothetical circumstance is selected to study the general coupling problem between the finite and infinite acoustic domains. We developed an equation that predicts the energy distribution and energy flow in the two spaces separated by a wall, and its computational examples are presented. Three typical radiation patterns that include steered, focused, and omnidirected are presented. A designed radiation pattern is also presented by using the optimal design algorithm.

  6. Topologically protected bound states in one-dimensional Floquet acoustic waveguide systems

    Science.gov (United States)

    Peng, Yu-Gui; Geng, Zhi-Guo; Zhu, Xue-Feng

    2018-03-01

    Topological manipulation of sound has recently been a hot spot in acoustics due to the fascinating property of defect immune transport. To the best of our knowledge, the studies on one-dimensional (1D) topological acoustic systems hitherto mainly focus on the case of the Su-Schrieffer-Heeger model. Here, we show that topologically protected bound states may also exist in 1D periodically modulated acoustic waveguide systems, viz., 1D Floquet topological insulators. The results show that tuning the coupling strength in a waveguide lattice could trigger topological phase transition, which gives rise to topologically protected interface states as we put together two waveguide lattices featured with different topological phases or winding numbers. However, for the combined lattice, input at the waveguides other than the interfacial ones will excite bulk states. We have further verified the robustness of interface bound states against the variation of coupling strengths between the two distinct waveguide lattices. This work extends the scope of topological acoustics and may promote potential applications for acoustic devices with topological functionalities.

  7. The integrated satellite-acoustic telemetry (iSAT) system for tracking marine megafauna

    KAUST Repository

    De la Torre, Pedro

    2012-10-06

    This document describes the integrated satellite-acoustic telemetry (iSAT) system: an autonomous modular system for tracking the movements of large pelagic fish using acoustic telemetry and satellite communications. The sensor platform is described along with the propulsion and navigation systems. An application for tracking the whale shark (Rhincodon typus) in the Red Sea is included along with a discussion of the technical difficulties that such a system faces.

  8. The integrated satellite-acoustic telemetry (iSAT) system for tracking marine megafauna

    KAUST Repository

    De la Torre, Pedro; Berumen, Michael L.; Salama, Khaled N.; Smith, E. Lloyd

    2012-01-01

    This document describes the integrated satellite-acoustic telemetry (iSAT) system: an autonomous modular system for tracking the movements of large pelagic fish using acoustic telemetry and satellite communications. The sensor platform is described along with the propulsion and navigation systems. An application for tracking the whale shark (Rhincodon typus) in the Red Sea is included along with a discussion of the technical difficulties that such a system faces.

  9. Ultrasound acoustic wave energy transfer and harvesting

    Science.gov (United States)

    Shahab, Shima; Leadenham, Stephen; Guillot, François; Sabra, Karim; Erturk, Alper

    2014-04-01

    This paper investigates low-power electricity generation from ultrasound acoustic wave energy transfer combined with piezoelectric energy harvesting for wireless applications ranging from medical implants to naval sensor systems. The focus is placed on an underwater system that consists of a pulsating source for spherical wave generation and a harvester connected to an external resistive load for quantifying the electrical power output. An analytical electro-acoustic model is developed to relate the source strength to the electrical power output of the harvester located at a specific distance from the source. The model couples the energy harvester dynamics (piezoelectric device and electrical load) with the source strength through the acoustic-structure interaction at the harvester-fluid interface. Case studies are given for a detailed understanding of the coupled system dynamics under various conditions. Specifically the relationship between the electrical power output and system parameters, such as the distance of the harvester from the source, dimensions of the harvester, level of source strength, and electrical load resistance are explored. Sensitivity of the electrical power output to the excitation frequency in the neighborhood of the harvester's underwater resonance frequency is also reported.

  10. Spatio-Temporal Analysis of Urban Acoustic Environments with Binaural Psycho-Acoustical Considerations for IoT-Based Applications.

    Science.gov (United States)

    Segura-Garcia, Jaume; Navarro-Ruiz, Juan Miguel; Perez-Solano, Juan J; Montoya-Belmonte, Jose; Felici-Castell, Santiago; Cobos, Maximo; Torres-Aranda, Ana M

    2018-02-26

    Sound pleasantness or annoyance perceived in urban soundscapes is a major concern in environmental acoustics. Binaural psychoacoustic parameters are helpful to describe generic acoustic environments, as it is stated within the ISO 12913 framework. In this paper, the application of a Wireless Acoustic Sensor Network (WASN) to evaluate the spatial distribution and the evolution of urban acoustic environments is described. Two experiments are presented using an indoor and an outdoor deployment of a WASN with several nodes using an Internet of Things (IoT) environment to collect audio data and calculate meaningful parameters such as the sound pressure level, binaural loudness and binaural sharpness. A chunk of audio is recorded in each node periodically with a microphone array and the binaural rendering is conducted by exploiting the estimated directional characteristics of the incoming sound by means of DOA estimation. Each node computes the parameters in a different location and sends the values to a cloud-based broker structure that allows spatial statistical analysis through Kriging techniques. A cross-validation analysis is also performed to confirm the usefulness of the proposed system.

  11. An explosive acoustic telemetry system for seabed penetrators

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, G.C.; Hickerson, J.

    1988-04-01

    This report discusses the design and past applications of an explosive acoustic telemetry system (EATS) for gathering and transmitting data from seabed penetrators. The system was first fielded in 1982 and has since been used to measure penetrator performance on three other occasions. Descriptions are given of the mechanical hardware, system electronics, and software.

  12. Hybrid CFD/CAA Modeling for Liftoff Acoustic Predictions

    Science.gov (United States)

    Strutzenberg, Louise L.; Liever, Peter A.

    2011-01-01

    This paper presents development efforts at the NASA Marshall Space flight Center to establish a hybrid Computational Fluid Dynamics and Computational Aero-Acoustics (CFD/CAA) simulation system for launch vehicle liftoff acoustics environment analysis. Acoustic prediction engineering tools based on empirical jet acoustic strength and directivity models or scaled historical measurements are of limited value in efforts to proactively design and optimize launch vehicles and launch facility configurations for liftoff acoustics. CFD based modeling approaches are now able to capture the important details of vehicle specific plume flow environment, identifY the noise generation sources, and allow assessment of the influence of launch pad geometric details and sound mitigation measures such as water injection. However, CFD methodologies are numerically too dissipative to accurately capture the propagation of the acoustic waves in the large CFD models. The hybrid CFD/CAA approach combines the high-fidelity CFD analysis capable of identifYing the acoustic sources with a fast and efficient Boundary Element Method (BEM) that accurately propagates the acoustic field from the source locations. The BEM approach was chosen for its ability to properly account for reflections and scattering of acoustic waves from launch pad structures. The paper will present an overview of the technology components of the CFD/CAA framework and discuss plans for demonstration and validation against test data.

  13. Airy acoustical-sheet spinner tweezers

    Science.gov (United States)

    Mitri, F. G.

    2016-09-01

    The Airy acoustical beam exhibits parabolic propagation and spatial acceleration, meaning that the propagation bending angle continuously increases before the beam trajectory reaches a critical angle where it decays after a propagation distance, without applying any external bending force. As such, it is of particular importance to investigate its properties from the standpoint of acoustical radiation force, spin torque, and particle dynamics theories, in the development of novel particle sorting techniques and acoustically mediated clearing systems. This work investigates these effects on a two-dimensional (2D) circular absorptive structure placed in the field of a nonparaxial Airy "acoustical-sheet" (i.e., finite beam in 2D), for potential applications in surface acoustic waves and acousto-fluidics. Based on the characteristics of the acoustic field, the beam is capable of manipulating the circular cylindrical fluid cross-section and guides it along a transverse or parabolic trajectory. This feature of Airy acoustical beams could lead to a unique characteristic in single-beam acoustical tweezers related to acoustical sieving, filtering, and removal of particles and cells from a section of a small channel. The analysis developed here is based on the description of the nonparaxial Airy beam using the angular spectrum decomposition of plane waves in close association with the partial-wave series expansion method in cylindrical coordinates. The numerical results demonstrate the ability of the nonparaxial Airy acoustical-sheet beam to pull, propel, or accelerate a particle along a parabolic trajectory, in addition to particle confinement in the transverse direction of wave propagation. Negative or positive radiation force and spin torque causing rotation in the clockwise or the anticlockwise direction can occur depending on the nondimensional parameter ka (where k is the wavenumber and a is the radius) and the location of the cylinder in the beam. Applications in

  14. Battlefield acoustics

    CERN Document Server

    Damarla, Thyagaraju

    2015-01-01

    This book presents all aspects of situational awareness in a battlefield using acoustic signals. It starts by presenting the science behind understanding and interpretation of sound signals. The book then goes on to provide various signal processing techniques used in acoustics to find the direction of sound source, localize gunfire, track vehicles, and detect people. The necessary mathematical background and various classification and fusion techniques are presented. The book contains majority of the things one would need to process acoustic signals for all aspects of situational awareness in one location. The book also presents array theory, which is pivotal in finding the direction of arrival of acoustic signals. In addition, the book presents techniques to fuse the information from multiple homogeneous/heterogeneous sensors for better detection. MATLAB code is provided for majority of the real application, which is a valuable resource in not only understanding the theory but readers, can also use the code...

  15. New leak detection and location techniques for pipework and vessels

    International Nuclear Information System (INIS)

    Jax, P.; Leuker, W.

    1992-01-01

    The new monitoring systems are based on the moisture measurement with permeable sensor tubing or on acoustic measurement of leakage noise. An important characteristic is the capability to detect and locate leakages sensitively. Various physical dimensions are measured and accordingly there are differences in response time, sensitivity, accuracy of location and the ability to make statements about leakage rate. This paper considers in detail the basic principles, the technical system, areas of application and experience available. (orig.) [de

  16. A method of acoustic wave registration and determination their generation region

    International Nuclear Information System (INIS)

    Kozin, I.D.; Marchenko, M.V.

    1998-01-01

    Here is presented a method of acoustic wave registration with using of a synchronous LF broadcasting system. This method of detection and determination of underground nuclear explosion location is based on a registration of ionospheric disturbances induced by acoustic waves at the region of LF sign al reflection. The measuring complex created in the institute of the Ionosphere /1/ allows to register amplitude-frequency characteristics of composite signal from synchronous broadcasting net

  17. A Mobile Acoustic Subsurface Sensing (MASS) system for rapid roadway assessment.

    Science.gov (United States)

    Lu, Yifeng; Zhang, Yi; Cao, Yinghong; McDaniel, J Gregory; Wang, Ming L

    2013-05-08

    Surface waves are commonly used for vibration-based nondestructive testing for infrastructure. Spectral Analysis of Surface Waves (SASW) has been used to detect subsurface properties for geologic inspections. Recently, efforts were made to scale down these subsurface detection approaches to see how they perform on small-scale structures such as concrete slabs and pavements. Additional efforts have been made to replace the traditional surface-mounted transducers with non-contact acoustic transducers. Though some success has been achieved, most of these new approaches are inefficient because they require point-to-point measurements or off-line signal analysis. This article introduces a Mobile Acoustic Subsurface Sensing system as MASS, which is an improved surface wave based implementation for measuring the subsurface profile of roadways. The compact MASS system is a 3-wheeled cart outfitted with an electromagnetic impact source, distance register, non-contact acoustic sensors and data acquisition/ processing equipment. The key advantage of the MASS system is the capability to collect measurements continuously at walking speed in an automatic way. The fast scan and real-time analysis advantages are based upon the non-contact acoustic sensing and fast air-coupled surface wave analysis program. This integration of hardware and software makes the MASS system an efficient mobile prototype for the field test.

  18. A Mobile Acoustic Subsurface Sensing (MASS System for Rapid Roadway Assessment

    Directory of Open Access Journals (Sweden)

    Ming L. Wang

    2013-05-01

    Full Text Available Surface waves are commonly used for vibration-based nondestructive testing for infrastructure. Spectral Analysis of Surface Waves (SASW has been used to detect subsurface properties for geologic inspections. Recently, efforts were made to scale down these subsurface detection approaches to see how they perform on small-scale structures such as concrete slabs and pavements. Additional efforts have been made to replace the traditional surface-mounted transducers with non-contact acoustic transducers. Though some success has been achieved, most of these new approaches are inefficient because they require point-to-point measurements or off-line signal analysis. This article introduces a Mobile Acoustic Subsurface Sensing system as MASS, which is an improved surface wave based implementation for measuring the subsurface profile of roadways. The compact MASS system is a 3-wheeled cart outfitted with an electromagnetic impact source, distance register, non-contact acoustic sensors and data acquisition/ processing equipment. The key advantage of the MASS system is the capability to collect measurements continuously at walking speed in an automatic way. The fast scan and real-time analysis advantages are based upon the non-contact acoustic sensing and fast air-coupled surface wave analysis program. This integration of hardware and software makes the MASS system an efficient mobile prototype for the field test.

  19. ION ACOUSTIC TURBULENCE, ANOMALOUS TRANSPORT, AND SYSTEM DYNAMICS IN HALL EFFECT THRUSTERS

    Science.gov (United States)

    2017-06-30

    NUMBER (Include area code) 30 June 2017 Briefing Charts 26 May 2017 - 30 June 2017 ION ACOUSTIC TURBULENCE, ANOMALOUS TRANSPORT, AND SYSTEM DYNAMICS ...Robert Martin N/A ION ACOUSTIC TURBULENCE, ANOMALOUS TRANSPORT, AND SYSTEM DYNAMICS IN HALL EFFECT THRUSTERS Robert Martin1, Jonathan Tran2 1AIR FORCE...Approved for Public Release; Distribution is Unlimited. PA# 17394 1 / 13 OUTLINE 1 INTRODUCTION 2 TRANSPORT 3 DYNAMIC SYSTEM 4 SUMMARY AND CONCLUSION

  20. LARA: Expert system for acoustic localization of robot in a LMFBR

    International Nuclear Information System (INIS)

    Lhuillier, C.; Malvache, P.

    1986-12-01

    The expert system LARA (Acoustic Localization of Autonomic Robot) has been developed to show the interest of introducing artificial intelligency for fine automatic positioning of refuelling machine in a LMFBR reactor. LARA which is equipped with an acoustic detector gives rapidly a good positioning on the fuel [fr

  1. Acoustically Driven Fluid and Particle Motion in Confined and Leaky Systems

    Science.gov (United States)

    Barnkob, Rune; Nama, Nitesh; Ren, Liqiang; Huang, Tony Jun; Costanzo, Francesco; Kähler, Christian J.

    2018-01-01

    The acoustic motion of fluids and particles in confined and acoustically leaky systems is receiving increasing attention for its use in medicine and biotechnology. A number of contradicting physical and numerical models currently exist, but their validity is uncertain due to the unavailability of hard-to-access experimental data for validation. We provide experimental benchmarking data by measuring 3D particle trajectories and demonstrate that the particle trajectories can be described numerically without any fitting parameter by a reduced-fluid model with leaky impedance-wall conditions. The results reveal the hitherto unknown existence of a pseudo-standing wave that drives the acoustic streaming as well as the acoustic radiation force on suspended particles.

  2. Systems and methods for biometric identification using the acoustic properties of the ear canal

    International Nuclear Information System (INIS)

    Bouchard, A.M.; Osbourn, G.C.

    1998-01-01

    The present invention teaches systems and methods for verifying or recognizing a person's identity based on measurements of the acoustic response of the individual's ear canal. The system comprises an acoustic emission device, which emits an acoustic source signal s(t), designated by a computer, into the ear canal of an individual, and an acoustic response detection device, which detects the acoustic response signal f(t). A computer digitizes the response (detected) signal f(t) and stores the data. Computer-implemented algorithms analyze the response signal f(t) to produce ear-canal feature data. The ear-canal feature data obtained during enrollment is stored on the computer, or some other recording medium, to compare the enrollment data with ear-canal feature data produced in a subsequent access attempt, to determine if the individual has previously been enrolled. The system can also be adapted for remote access applications. 5 figs

  3. Systems and methods for biometric identification using the acoustic properties of the ear canal

    Science.gov (United States)

    Bouchard, Ann Marie; Osbourn, Gordon Cecil

    1998-01-01

    The present invention teaches systems and methods for verifying or recognizing a person's identity based on measurements of the acoustic response of the individual's ear canal. The system comprises an acoustic emission device, which emits an acoustic source signal s(t), designated by a computer, into the ear canal of an individual, and an acoustic response detection device, which detects the acoustic response signal f(t). A computer digitizes the response (detected) signal f(t) and stores the data. Computer-implemented algorithms analyze the response signal f(t) to produce ear-canal feature data. The ear-canal feature data obtained during enrollment is stored on the computer, or some other recording medium, to compare the enrollment data with ear-canal feature data produced in a subsequent access attempt, to determine if the individual has previously been enrolled. The system can also be adapted for remote access applications.

  4. Golden Gate and Pt. Reyes Acoustic Detections

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains detections of acoustic tagged fish from two general locations: Golden Gate (east and west line) and Pt. Reyes. Several Vemco 69khz acoustic...

  5. Acoustic energy harvesting based on a planar acoustic metamaterial

    Science.gov (United States)

    Qi, Shuibao; Oudich, Mourad; Li, Yong; Assouar, Badreddine

    2016-06-01

    We theoretically report on an innovative and practical acoustic energy harvester based on a defected acoustic metamaterial (AMM) with piezoelectric material. The idea is to create suitable resonant defects in an AMM to confine the strain energy originating from an acoustic incidence. This scavenged energy is converted into electrical energy by attaching a structured piezoelectric material into the defect area of the AMM. We show an acoustic energy harvester based on a meta-structure capable of producing electrical power from an acoustic pressure. Numerical simulations are provided to analyze and elucidate the principles and the performances of the proposed system. A maximum output voltage of 1.3 V and a power density of 0.54 μW/cm3 are obtained at a frequency of 2257.5 Hz. The proposed concept should have broad applications on energy harvesting as well as on low-frequency sound isolation, since this system acts as both acoustic insulator and energy harvester.

  6. Marine bioacoustics and technology: The new world of marine acoustic ecology

    Science.gov (United States)

    Hastings, Mardi C.; Au, Whitlow W. L.

    2012-11-01

    Marine animals use sound for communication, navigation, predator avoidance, and prey detection. Thus the rise in acoustic energy associated with increasing human activity in the ocean has potential to impact the lives of marine animals. Thirty years ago marine bioacoustics primarily focused on evaluating effects of human-generated sound on hearing and behavior by testing captive animals and visually observing wild animals. Since that time rapidly changing electronic and computing technologies have yielded three tools that revolutionized how bioacousticians study marine animals. These tools are (1) portable systems for measuring electrophysiological auditory evoked potentials, (2) miniaturized tags equipped with positioning sensors and acoustic recording devices for continuous short-term acoustical observation rather than intermittent visual observation, and (3) passive acoustic monitoring (PAM) systems for remote long-term acoustic observations at specific locations. The beauty of these breakthroughs is their direct applicability to wild animals in natural habitats rather than only to animals held in captivity. Hearing capabilities of many wild species including polar bears, beaked whales, and reef fishes have now been assessed by measuring their auditory evoked potentials. Miniaturized acoustic tags temporarily attached to an animal to record its movements and acoustic environment have revealed the acoustic foraging behavior of sperm and beaked whales. Now tags are being adapted to fishes in effort to understand their behavior in the presence of noise. Moving and static PAM systems automatically detect and characterize biological and physical features of an ocean area without adding any acoustic energy to the environment. PAM is becoming a powerful technique for understanding and managing marine habitats. This paper will review the influence of these transformative tools on the knowledge base of marine bioacoustics and elucidation of relationships between marine

  7. Smart location system; Sistema de localizacao inteligente Smart Location System

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Jose Augusto Pereira da; Antunes, Rodrigo de Castro; Azevedo, Fabio Augusto Ferreira de [PipeWay Engenharia, Rio de Janeiro, RJ (Brazil); Afonso, Orlando de Jesus Ribeiro [Instituto de Pesquisas da Marinha, Rio de Janeiro, RJ (Brazil); Matsuura, Minoru; Santa Cruz, Sergio de Freitas [TRANSPETRO - PETROBRAS Transportes, Rio de Janeiro, RJ (Brazil); Santos, Jose Alberto Costa dos; Hashiguchi, Decio Issao [GDK Engenharia (Brazil)

    2003-07-01

    This paper describes the technology used in the Intelligent Location System developed by Pipeway and includes some of the results already obtained optimizing repair time and logistic costs during the location of anomalies detected by intelligent pigs, a joint operation within the scope of the contract for Sub sea Pipeline Recovery in the Guanabara Bay with PETROBRAS/TRANSPETRO and GDK Engenharia. The system uses the ELF (Extra Low Frequency) transmission and reception technology at points near a pipe, with or without concrete coating, whose signals are recorded in the inspection tool memory to accurately establish reference points, thus preventing excessive dig work or dredging when human and operational risks tend to be high. (author)

  8. An acoustic system for autonomous navigation and tracking of marine fauna

    KAUST Repository

    De la Torre, Pedro

    2014-08-01

    A marine acoustic system for underwater target tracking is described. This system is part of the Integrated Satellite and Acoustic Telemetry (iSAT) project to study marine fauna. It is a microcontroller-based underwater projector and receiver. A narrow-band, passive sonar detection architecture is described from signal generation, through transduction, reception, signal processing and up to tone extraction. Its circuit and operation principles are described. Finally, a comparison between the current energy detection method versus an alternative matched filter approach is included.

  9. Acoustic Emission Technology and Application

    International Nuclear Information System (INIS)

    Joo, Y. S.; Lim, S. H.; Eom, H. S.; Kim, J. H.; Jung, H. K.

    2003-10-01

    Acoustic emission is the elastic wave that is generated by the rapid release of energy from the localized sources within a material. After the observation of acoustic emission phenomenon in 1950, the research and further investigation had been performed. Acoustic emission examination becomes a rapidly matured nondestructive testing method with demonstrated capabilities for characterizing material behavior and for detecting the defect. It is of interest as a possible passive monitoring technique for detecting, locating and characterizing the defects in component and structure. Acoustic emission technology has recently strengthened the on-line monitoring application for the detection of incipient failures and the assurance of structural integrity. The field of acoustic emission testing is still growing vigorously and presents many challenges. Especially, acoustic emission has been successfully applied in the leak detection of primary pressure boundary of nuclear power plants. In this state-of-art report, the principle, measurement and field applications of acoustic emission technique is reviewed and summarized. Acoustic emission technology will contribute to the assurance of nuclear safety as the on-line monitoring technique of structural integrity of NSSS components and structures

  10. Spatio-Temporal Analysis of Urban Acoustic Environments with Binaural Psycho-Acoustical Considerations for IoT-Based Applications

    Directory of Open Access Journals (Sweden)

    Jaume Segura-Garcia

    2018-02-01

    Full Text Available Sound pleasantness or annoyance perceived in urban soundscapes is a major concern in environmental acoustics. Binaural psychoacoustic parameters are helpful to describe generic acoustic environments, as it is stated within the ISO 12913 framework. In this paper, the application of a Wireless Acoustic Sensor Network (WASN to evaluate the spatial distribution and the evolution of urban acoustic environments is described. Two experiments are presented using an indoor and an outdoor deployment of a WASN with several nodes using an Internet of Things (IoT environment to collect audio data and calculate meaningful parameters such as the sound pressure level, binaural loudness and binaural sharpness. A chunk of audio is recorded in each node periodically with a microphone array and the binaural rendering is conducted by exploiting the estimated directional characteristics of the incoming sound by means of DOA estimation. Each node computes the parameters in a different location and sends the values to a cloud-based broker structure that allows spatial statistical analysis through Kriging techniques. A cross-validation analysis is also performed to confirm the usefulness of the proposed system.

  11. Performance Evaluation of a Biometric System Based on Acoustic Images

    Science.gov (United States)

    Izquierdo-Fuente, Alberto; del Val, Lara; Jiménez, María I.; Villacorta, Juan J.

    2011-01-01

    An acoustic electronic scanning array for acquiring images from a person using a biometric application is developed. Based on pulse-echo techniques, multifrequency acoustic images are obtained for a set of positions of a person (front, front with arms outstretched, back and side). Two Uniform Linear Arrays (ULA) with 15 λ/2-equispaced sensors have been employed, using different spatial apertures in order to reduce sidelobe levels. Working frequencies have been designed on the basis of the main lobe width, the grating lobe levels and the frequency responses of people and sensors. For a case-study with 10 people, the acoustic profiles, formed by all images acquired, are evaluated and compared in a mean square error sense. Finally, system performance, using False Match Rate (FMR)/False Non-Match Rate (FNMR) parameters and the Receiver Operating Characteristic (ROC) curve, is evaluated. On the basis of the obtained results, this system could be used for biometric applications. PMID:22163708

  12. Performance Evaluation of a Biometric System Based on Acoustic Images

    Directory of Open Access Journals (Sweden)

    Juan J. Villacorta

    2011-10-01

    Full Text Available An acoustic electronic scanning array for acquiring images from a person using a biometric application is developed. Based on pulse-echo techniques, multifrequency acoustic images are obtained for a set of positions of a person (front, front with arms outstretched, back and side. Two Uniform Linear Arrays (ULA with 15 l/2-equispaced sensors have been employed, using different spatial apertures in order to reduce sidelobe levels. Working frequencies have been designed on the basis of the main lobe width, the grating lobe levels and the frequency responses of people and sensors. For a case-study with 10 people, the acoustic profiles, formed by all images acquired, are evaluated and compared in a mean square error sense. Finally, system performance, using False Match Rate (FMR/False Non-Match Rate (FNMR parameters and the Receiver Operating Characteristic (ROC curve, is evaluated. On the basis of the obtained results, this system could be used for biometric applications.

  13. Time reversal signal processing in acoustic emission testing

    Czech Academy of Sciences Publication Activity Database

    Převorovský, Zdeněk; Krofta, Josef; Kober, Jan; Dvořáková, Zuzana; Chlada, Milan; Dos Santos, S.

    2014-01-01

    Roč. 19, č. 12 (2014) ISSN 1435-4934. [European Conference on Non-Destructive Testing (ECNDT 2014) /11./. Praha, 06.10.2014-10.10.2014] Institutional support: RVO:61388998 Keywords : acoustic emission (AE) * ultrasonic testing (UT) * signal processing * source location * time reversal acoustic s * acoustic emission * signal processing and transfer Subject RIV: BI - Acoustic s http://www.ndt.net/events/ECNDT2014/app/content/Slides/637_Prevorovsky.pdf

  14. AMADEUS—The acoustic neutrino detection test system of the ANTARES deep-sea neutrino telescope

    Science.gov (United States)

    Aguilar, J. A.; Al Samarai, I.; Albert, A.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M.; Assis Jesus, A. C.; Astraatmadja, T.; Aubert, J.-J.; Auer, R.; Barbarito, E.; Baret, B.; Basa, S.; Bazzotti, M.; Bertin, V.; Biagi, S.; Bigongiari, C.; Bou-Cabo, M.; Bouwhuis, M. C.; Brown, A.; Brunner, J.; Busto, J.; Camarena, F.; Capone, A.; Cârloganu, C.; Carminati, G.; Carr, J.; Cassano, B.; Castorina, E.; Cavasinni, V.; Cecchini, S.; Ceres, A.; Charvis, Ph.; Chiarusi, T.; Chon Sen, N.; Circella, M.; Coniglione, R.; Costantini, H.; Cottini, N.; Coyle, P.; Curtil, C.; de Bonis, G.; Decowski, M. P.; Dekeyser, I.; Deschamps, A.; Distefano, C.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; Emanuele, U.; Ernenwein, J.-P.; Escoffier, S.; Fehr, F.; Fiorello, C.; Flaminio, V.; Fritsch, U.; Fuda, J.-L.; Gay, P.; Giacomelli, G.; Gómez-González, J. P.; Graf, K.; Guillard, G.; Halladjian, G.; Hallewell, G.; van Haren, H.; Heijboer, A. J.; Heine, E.; Hello, Y.; Hernández-Rey, J. J.; Herold, B.; Hößl, J.; de Jong, M.; Kalantar-Nayestanaki, N.; Kalekin, O.; Kappes, A.; Katz, U.; Keller, P.; Kooijman, P.; Kopper, C.; Kouchner, A.; Kretschmer, W.; Lahmann, R.; Lamare, P.; Lambard, G.; Larosa, G.; Laschinsky, H.; Le Provost, H.; Lefèvre, D.; Lelaizant, G.; Lim, G.; Lo Presti, D.; Loehner, H.; Loucatos, S.; Louis, F.; Lucarelli, F.; Mangano, S.; Marcelin, M.; Margiotta, A.; Martinez-Mora, J. A.; Mazure, A.; Mongelli, M.; Montaruli, T.; Morganti, M.; Moscoso, L.; Motz, H.; Naumann, C.; Neff, M.; Ostasch, R.; Palioselitis, D.; Păvălaş, G. E.; Payre, P.; Petrovic, J.; Picot-Clemente, N.; Picq, C.; Popa, V.; Pradier, T.; Presani, E.; Racca, C.; Radu, A.; Reed, C.; Riccobene, G.; Richardt, C.; Rujoiu, M.; Ruppi, M.; Russo, G. V.; Salesa, F.; Sapienza, P.; Schöck, F.; Schuller, J.-P.; Shanidze, R.; Simeone, F.; Spurio, M.; Steijger, J. J. M.; Stolarczyk, Th.; Taiuti, M.; Tamburini, C.; Tasca, L.; Toscano, S.; Vallage, B.; van Elewyck, V.; Vannoni, G.; Vecchi, M.; Vernin, P.; Wijnker, G.; de Wolf, E.; Yepes, H.; Zaborov, D.; Zornoza, J. D.; Zúñiga, J.

    2011-01-01

    The AMADEUS (ANTARES Modules for the Acoustic Detection Under the Sea) system which is described in this article aims at the investigation of techniques for acoustic detection of neutrinos in the deep sea. It is integrated into the ANTARES neutrino telescope in the Mediterranean Sea. Its acoustic sensors, installed at water depths between 2050 and 2300 m, employ piezo-electric elements for the broad-band recording of signals with frequencies ranging up to 125 kHz. The typical sensitivity of the sensors is around -145 dB re 1 V/μPa (including preamplifier). Completed in May 2008, AMADEUS consists of six “acoustic clusters”, each comprising six acoustic sensors that are arranged at distances of roughly 1 m from each other. Two vertical mechanical structures (so-called lines) of the ANTARES detector host three acoustic clusters each. Spacings between the clusters range from 14.5 to 340 m. Each cluster contains custom-designed electronics boards to amplify and digitise the acoustic signals from the sensors. An on-shore computer cluster is used to process and filter the data stream and store the selected events. The daily volume of recorded data is about 10 GB. The system is operating continuously and automatically, requiring only little human intervention. AMADEUS allows for extensive studies of both transient signals and ambient noise in the deep sea, as well as signal correlations on several length scales and localisation of acoustic point sources. Thus the system is excellently suited to assess the background conditions for the measurement of the bipolar pulses expected to originate from neutrino interactions.

  15. Mean Flow Augmented Acoustics in Rocket Systems

    Science.gov (United States)

    Fischbach, Sean R.

    2014-01-01

    Oscillatory motion in solid rocket motors and liquid engines has long been a subject of concern. Many rockets display violent fluctuations in pressure, velocity, and temperature originating from the complex interactions between the combustion process and gas dynamics. The customary approach to modeling acoustic waves inside a rocket chamber is to apply the classical inhomogeneous wave equation to the combustion gas. The assumption of a linear, non-dissipative wave in a quiescent fluid remains valid while the acoustic amplitudes are small and local gas velocities stay below Mach 0.2. The converging section of a rocket nozzle, where gradients in pressure, density, and velocity become large, is a notable region where this approach is not applicable. The expulsion of unsteady energy through the nozzle of a rocket is identified as the predominate source of acoustic damping for most rocket systems. An accurate model of the acoustic behavior within this region where acoustic modes are influenced by the presence of a steady mean flow is required for reliable stability predictions. Recently, an approach to address nozzle damping with mean flow effects was implemented by French [1]. This new approach extends the work originated by Sigman and Zinn [2] by solving the acoustic velocity potential equation (AVPE) formulated by perturbing the Euler equations [3]. The acoustic velocity potential (psi) describing the acoustic wave motion in the presence of an inhomogeneous steady high-speed flow is defined by, (del squared)(psi) - (lambda/c)(exp 2)(psi) - M(dot)[M(dot)(del)(del(psi))] - 2(lambda(M/c) + (M(dot)del(M))(dot)del(psi)-2(lambda)(psi)[M(dot)del(1/c)]=0 (1) with M as the Mach vector, c as the speed of sound, and lambda as the complex eigenvalue. French apply the finite volume method to solve the steady flow field within the combustion chamber and nozzle with inviscid walls. The complex eigenvalues and eigenvector are determined with the use of the ARPACK eigensolver. The

  16. On the influence of drag effect on acoustic modes in two-condensate relativistic superfluid systems

    International Nuclear Information System (INIS)

    Vil'chinskij, S.I.

    1999-01-01

    Equations of velocities of acoustic excitations in a relativistic two-condensate superfluid system are derived with due account of reciprocal drag of superfluid motion (drag effect). The influence of the drag effect on acoustic modes in the system is considered. It is shown that the effect does not influence the nature of acoustic excitation oscillations but produces changes in the velocities of the second, third and fourth sounds

  17. Jedan pristup u oceni efektivnosti sistema za zvukometrijsko izviđanje 'Boomerang' / One approach to the evaluation of the effectiveness of the boomerang system for acoustic source localization and identification

    Directory of Open Access Journals (Sweden)

    Miroslav R. Terzić

    2010-07-01

    Full Text Available U radu je prikazan jedan pristup u oceni efektivnosti sistema za zvukometrijsko izviđanje. Sistem za zvukometrijsko izviđanje modelovan je kao sistem masovnog opsluživanja, opisana su stanja sistema, parametri i izveden izraz za određivanje verovatnoće opsluživanja sistema za zvukometrijskao izviđanje, kao kriterijuma za ocenu efektivnosti. / One approach to the evaluation of the effectiveness of a system for acoustic source localization and identification has been shown in this article. The system for acoustic source localization and identification has been presented as a model of mass servicing system. The states of the system as well as its features have been described while the formula for service probability determination has been derived as a criterion for effectiveness evaluation. The introductory part of the article describes the system for acoustic source localization and identification and shows a model for quantity estimation of the function of technical system effectiveness E (t. The system effectiveness represents a probability of system initiation as well as a probability of its successful mission accomplishment on the basis of designed capabilities within the given time period and operational conditions. The basic characteristics of the Boomerang system for acoustic source localization and identification show the system elements and its designed capability to detect, analyse and distribute acoustic source location data. The analytical model for the evaluation of the effectiveness of the Boomerang system for acoustic source localization and identification shows that 'n' stations for acoustic source localization can exchange information with each other using the network link. The system conditions are described and the expression for the determination of service probability as a criterion for system effectiveness evaluation is derived. The evaluation of the effectiveness of the Boomerang system for acoustic source

  18. Combined Opto-Acoustical sensor modules for KM3NeT

    International Nuclear Information System (INIS)

    Enzenhöfer, A.

    2013-01-01

    KM3NeT is a future multi-cubic-kilometre water Cherenkov neutrino telescope currently entering a first construction phase. It will be located in the Mediterranean Sea and comprise about 600 vertical structures called detection units. Each of these detection units has a length of several hundred metres and is anchored to the sea bed on one side and held taut by a buoy on the other side. The detection units are thus subject to permanent movement due to sea currents. Modules holding photosensors and additional equipment are equally distributed along the detection units. The relative positions of the photosensors has to be known with an uncertainty below 20 cm in order to achieve the necessary precision for neutrino astronomy. These positions can be determined with an acoustic positioning system: dedicated acoustic emitters located at known positions and acoustic receivers along each detection unit. This article describes the approach to combine an acoustic receiver with the photosensors inside one detection module using a common power supply and data readout. The advantage of this approach lies in a reduction of underwater connectors and module configurations as well as in the compactification of the detection units integrating the auxiliary devices necessary for their successful operation.

  19. Comparison of PAM Systems for Acoustic Monitoring and Further Risk Mitigation Application.

    Science.gov (United States)

    Ludwig, Stefan; Kreimeyer, Roman; Knoll, Michaela

    2016-01-01

    We present results of the SIRENA 2011 research cruises conducted by the NATO Undersea Research Centre (NURC) and joined by the Research Department for Underwater Acoustics and Geophysics (FWG), Bundeswehr Technical Centre (WTD 71) and the Universities of Kiel and Pavia. The cruises were carried out in the Ligurian Sea. The main aim of the FWG was to test and evaluate the newly developed towed hydrophone array as a passive acoustic monitoring (PAM) tool for risk mitigation applications. The system was compared with the PAM equipment used by the other participating institutions. Recorded sounds were used to improve an automatic acoustic classifier for marine mammals, and validated acoustic detections by observers were compared with the results of the classifier.

  20. Testing of an acoustic smolt deflection system, Blantyre hydroelectric power scheme

    International Nuclear Information System (INIS)

    1996-01-01

    The aim of this study was to test the effectiveness of an underwater acoustic barrier as a means of preventing the entry of salmon (Salmo salar) and sea trout (Salmo trutta) smolts and other fish into the water intake of a hydro-electric power (HEP) station. A secondary objective was to measure the injury rate of fish passed through the turbine, so that the risk to any fish that penetrated the acoustic barrier could also be determined. The test site, which was a 575kW Kaplan plant located at Blantyre on the R. Clyde, Lanarkshire, was selected as being representative of run-of-river sites currently being developed under the Government's NFFO (Non-Fossil Fuel Obligation) and SRO (Scottish Renewables Order) schemes. A further objective was to disseminate information arising from the project to the scientific and HEP community. (author)

  1. Analysis of acoustic data from the PFR SGU condition monitor

    International Nuclear Information System (INIS)

    Rowley, R.; Airey, J.

    1990-01-01

    This paper gives an outline description of an acoustic monitoring system which has been installed on the SGU of the Prototype Fast Reactor (PFR) at Dounreay with the objective of giving early warning of any change in noise output which could be related to potentially damaging vibrations within the units. Data obtained from this PFR monitoring system is playing an important part in the development of acoustic instrumentation for leak detection although this had not been the primary objective of this particular installation. The PFR has three secondary circuits each containing an evaporator, a superheater and a reheater giving a total of nine SGUs. Although the design of the units is different from that intended for EFR, the measurements provide a valuable source of information on the character and amplitude of acoustic background noise in operational steam generator units. The vibration monitoring system uses the waveguides originally installed during reactor commissioning for leak detection studies. Twelve acoustic waveguides are fitted to the shell of each of the units. The superheaters and reheaters have three waveguides at each of four axial levels, while the evaporators have four waveguides at each of three axial levels. In addition the evaporators have a small number of waveguides attached to the top flange of the unit. Each waveguide is fitted with an accelerometer to record the acoustic signal from the SGU. Tape recordings of the acoustic noise from each unit are made on a regular basis and the tapes analysed on an automated analysis system which has been developed to extract and store in a database about 20 characteristic features from the data. The paper gives examples of the background noise from the SGU. The data demonstrates the use of location techniques to identify prominent acoustic source. 8 figs

  2. Methods And Systems For Using Reference Images In Acoustic Image Processing

    Science.gov (United States)

    Moore, Thomas L.; Barter, Robert Henry

    2005-01-04

    A method and system of examining tissue are provided in which a field, including at least a portion of the tissue and one or more registration fiducials, is insonified. Scattered acoustic information, including both transmitted and reflected waves, is received from the field. A representation of the field, including both the tissue and the registration fiducials, is then derived from the received acoustic radiation.

  3. Research and Design on Trigger System Based on Acoustic Delay Correlation Filtering

    Directory of Open Access Journals (Sweden)

    Zhiyong Lei

    2014-01-01

    Full Text Available In the exterior trajectory test, there usually needs a muzzle or a gun muzzle trigger system to be used as start signal for other measuring device, the customary trigger systems include off- target, infrared and acoustic detection system. But inherent echo reflection of the acoustic detection system makes the original signal of sound trigger submerged in various echo interference for bursts and shooting in a closed room, so that it can’t produce accurate trigger. In order to solve this defect, this paper analyzed the mathematical model based on acoustic delay correlation filtering in detail, then put forward the constraint condition with minimum path for delay correlation filtering. In this constraint condition, delay correlation filtering can do de-noising operation accurately. In order to verify accuracy and actual performance of the model, a MEMS sound sensor was used to implement mathematical model onto project, experimental results show that this system can filter out the every path sound bounce echoes of muzzle shock wave signal and produce the desired trigger signal accurately.

  4. Generation and control of sound bullets with a nonlinear acoustic lens.

    Science.gov (United States)

    Spadoni, Alessandro; Daraio, Chiara

    2010-04-20

    Acoustic lenses are employed in a variety of applications, from biomedical imaging and surgery to defense systems and damage detection in materials. Focused acoustic signals, for example, enable ultrasonic transducers to image the interior of the human body. Currently however the performance of acoustic devices is limited by their linear operational envelope, which implies relatively inaccurate focusing and low focal power. Here we show a dramatic focusing effect and the generation of compact acoustic pulses (sound bullets) in solid and fluid media, with energies orders of magnitude greater than previously achievable. This focusing is made possible by a tunable, nonlinear acoustic lens, which consists of ordered arrays of granular chains. The amplitude, size, and location of the sound bullets can be controlled by varying the static precompression of the chains. Theory and numerical simulations demonstrate the focusing effect, and photoelasticity experiments corroborate it. Our nonlinear lens permits a qualitatively new way of generating high-energy acoustic pulses, which may improve imaging capabilities through increased accuracy and signal-to-noise ratios and may lead to more effective nonintrusive scalpels, for example, for cancer treatment.

  5. ACOUSTIC LOCATION OF LEAKS IN PRESSURIZED UNDER- GROUND PETROLEUM PIPELINES

    Science.gov (United States)

    Experiments were conducted at the Underground Storage Tank (UST) Test Apparatus Pipeline in which three acoustic sensors separated by a maximum distance of 38.1 m (125 ft) were used to monitor signals produced by 11.4-, 5.7-, and 3.8-L/h (3.0-, 1.5-, and 1.0-gal/h) leaks in th...

  6. An experimental analysis of fracture mechanisms by acoustic ...

    African Journals Online (AJOL)

    rupture under monotonic loading in tensile test of a carbon ... respectively the longitudinal, transversal and ..... (1) location of acoustic output source, (2) Sensors and acoustic source position for 4 channel position,. O(x,y) ..... Due to multiple.

  7. Acoustic transmitter and receiver performance in freshwater and estuarine environments

    Science.gov (United States)

    We report on the performance of passive acoustic receivers intended to detect the passage of 281 acoustically tagged migratory salmonids in two Oregon coastal watersheds. We found that ambient acoustic noise can vary considerably with location, and that “sync” pulses thought to ...

  8. Acoustic Band Gaps in Three-Dimensional NaCl-Type Acoustic Crystals

    International Nuclear Information System (INIS)

    Nong-Yu, Fang; Fu-Gen, Wu; Xin, Zhang

    2008-01-01

    We present the acoustic band gaps (ABGs) for a geometry of three-dimensional complex acoustic crystals: the NaCl-type structure. By using the super cell method based on the plane-wave expansion method (PWE), we study the three configurations formed by water objects (either a sphere of different sizes or a cube) located at the vertices of simple cubic (SC) lattice and surrounded by mercury background. The numerical results show that ABGs larger than the original SC structure for all the three configurations can be obtained by adjusting the length-diameter ratio of adjacent objects but keeping the filling fraction (f = 0.25) of the unit cell unchanged. We also compare our results with that of 3D solid composites and find that the ABGs in liquid composites are insensitive to the shapes as that in the solid composites. We further prove that the decrease of the translation group symmetry is more efficient in creating the ABGs in 3D water-mercury systems. (fundamental areas of phenomenology (including applications))

  9. iSAT: The Integrated Satellite and Acoustic Telemetry system for tracking marine megafauna

    KAUST Repository

    De La Torre, Pedro R.

    2014-05-01

    In this dissertation an innovative technology to study whale sharks, Rhincodon typus is presented. The Integrated Satellite and Acoustic Telemetry project (iSAT) combines underwater acoustic telemetry, autonomous navigation and radio frequency communications into a standalone system. The whale shark, a resident of the Saudi Arabian Red Sea, is the target of the study. The technology presented is designed to help close current gaps in the knowledge of whale shark biology; these are gaps that prohibit the design of optimal conservation strategies. Unfortunately, the various existing tracking technologies each have limitations and are unable to solve all the unanswered questions. Whale shark populations are increasingly threatened by anthropogenic activities such as targeted and indirect fishing pressure, creating an urgent need for better management practices. This dissertation addresses the current state-of-the-art of relevant technologies, including autonomous surface vehicles (ASVs), sensors for research in the ocean and remote monitoring of wild fauna (biotelemetry). iSAT contains components of all of these technologies, but the primary achievement of this dissertation is the development of iSAT’s Acoustic Tracking System (ATS). Underwater, the most efficient way of transmitting energy through long distances is sound. An electronic tag is attached to an animal and works as its acoustic identifier. iSAT’s hydrophone array detects the presence and direction of the acoustic signal generated by the tag. The expected performance, range, and capacity to tell the direction to the tag are explained and compared to the actual measured values. The first operational iSAT ATS is demonstrated. This work represents significant advancement towards a fully autonomous iSAT system. Developments on the power electronics, navigation, renewable energy harvesting, and other modules are included in this research. With the recent integration of digital acquisition systems, i

  10. Practical acoustic emission testing

    CERN Document Server

    2016-01-01

    This book is intended for non-destructive testing (NDT) technicians who want to learn practical acoustic emission testing based on level 1 of ISO 9712 (Non-destructive testing – Qualification and certification of personnel) criteria. The essential aspects of ISO/DIS 18436-6 (Condition monitoring and diagnostics of machines – Requirements for training and certification of personnel, Part 6: Acoustic Emission) are explained, and readers can deepen their understanding with the help of practice exercises. This work presents the guiding principles of acoustic emission measurement, signal processing, algorithms for source location, measurement devices, applicability of testing methods, and measurement cases to support not only researchers in this field but also and especially NDT technicians.

  11. Acoustic reflection log in transversely isotropic formations

    Science.gov (United States)

    Ronquillo Jarillo, G.; Markova, I.; Markov, M.

    2018-01-01

    We have calculated the waveforms of sonic reflection logging for a fluid-filled borehole located in a transversely isotropic rock. Calculations have been performed for an acoustic impulse source with the characteristic frequency of tens of kilohertz that is considerably less than the frequencies of acoustic borehole imaging tools. It is assumed that the borehole axis coincides with the axis of symmetry of the transversely isotropic rock. It was shown that the reflected wave was excited most efficiently at resonant frequencies. These frequencies are close to the frequencies of oscillations of a fluid column located in an absolutely rigid hollow cylinder. We have shown that the acoustic reverberation is controlled by the acoustic impedance of the rock Z = Vphρs for fixed parameters of the borehole fluid, where Vph is the velocity of horizontally propagating P-wave; ρs is the rock density. The methods of waveform processing to determine the parameters characterizing the reflected wave have been discussed.

  12. R&D for an innovative acoustic positioning system for the KM3NeT neutrino telescope

    Science.gov (United States)

    Ameli, F.; Ardid, M.; Bertin, V.; Bonori, M.; Bou-Cabo, M.; Calì, C.; D'Amico, A.; Giovanetti, G.; Imbesi, M.; Keller, P.; Larosa, G.; Llorens, C. D.; Masullo, R.; Randazzo, N.; Riccobene, G.; Speziale, F.; Viola, S.; KM3NeT Consortium

    2011-01-01

    An innovative Acoustic Positioning System for the km3-scale neutrino telescope has been designed and is under realization within the KM3NeT Consortium. Compared to the Acoustic Positioning Systems used for the km3 demonstrators, ANTARES and NEMO Phase 1, this new system is based on the “all data to shore” concept and it will permit the enhancement of detector positioning performances, reduction of costs and its use as real-time monitor of environmental acoustic noise.

  13. Status of U.S. evaluations of acoustic detection of in-sodium water leaks

    International Nuclear Information System (INIS)

    Fletcher, F.L.; Neely, H.H.

    1990-01-01

    An overview of the United States testing program to evaluate acoustic leak detection and location systems on simulated water leaks in functional liquid sodium steam generators is provided. Testing was conducted on the modular hockey stick steam generator during the large leak test program in the LLTR, on the CRBR prototype hockey stick steam generators in SCTI, on a double wall tube steam generator installed in EBR-II and on the helical coil steam generator tested in SCTI. These test programs have demonstrated the acoustic leak detection system potential, however, additional development is required before the system can perform to its effective and required potential. (author). 6 figs

  14. Miniature acoustic wave lysis system and uses thereof

    Science.gov (United States)

    Branch, Darren W.; Vreeland, Erika Cooley; Smith, Gennifer Tanabe

    2016-12-06

    The present invention relates to an acoustic lysis system including a disposable cartridge that can be reversibly coupled to a platform having a small, high-frequency piezoelectric transducer array. In particular, the system releases viable DNA, RNA, and proteins from human or bacterial cells, without chemicals or additional processing, to enable high-speed sample preparation for clinical point-of-care medical diagnostics and use with nano/microfluidic cartridges. Also described herein are methods of making and using the system of the invention.

  15. Nondestructive Evaluation of Concrete Bridge Decks with Automated Acoustic Scanning System and Ground Penetrating Radar.

    Science.gov (United States)

    Sun, Hongbin; Pashoutani, Sepehr; Zhu, Jinying

    2018-06-16

    Delamanintions and reinforcement corrosion are two common problems in concrete bridge decks. No single nondestructive testing method (NDT) is able to provide comprehensive characterization of these defects. In this work, two NDT methods, acoustic scanning and Ground Penetrating Radar (GPR), were used to image a straight concrete bridge deck and a curved intersection ramp bridge. An acoustic scanning system has been developed for rapid delamination mapping. The system consists of metal-ball excitation sources, air-coupled sensors, and a GPS positioning system. The acoustic scanning results are presented as a two-dimensional image that is based on the energy map in the frequency range of 0.5⁻5 kHz. The GPR scanning results are expressed as the GPR signal attenuation map to characterize concrete deterioration and reinforcement corrosion. Signal processing algorithms for both methods are discussed. Delamination maps from the acoustic scanning are compared with deterioration maps from the GPR scanning on both bridges. The results demonstrate that combining the acoustic and GPR scanning results will provide a complementary and comprehensive evaluation of concrete bridge decks.

  16. A method for Perceptual Assessment of Automotive Audio Systems and Cabin Acoustics

    DEFF Research Database (Denmark)

    Kaplanis, Neofytos; Bech, Søren; Sakari, Tervo

    2016-01-01

    This paper reports the design and implementation of a method to perceptually assess the acoustical prop- erties of a car cabin and the subsequent sound reproduction properties of automotive audio systems. Here, we combine Spatial Decomposition Method and Rapid Sensory Analysis techniques. The for......This paper reports the design and implementation of a method to perceptually assess the acoustical prop- erties of a car cabin and the subsequent sound reproduction properties of automotive audio systems. Here, we combine Spatial Decomposition Method and Rapid Sensory Analysis techniques...

  17. Numerical analysis of the resonance mechanism of the lumped parameter system model for acoustic mine detection

    International Nuclear Information System (INIS)

    Wang Chi; Zhou Yu-Qiu; Shen Gao-Wei; Wu Wen-Wen; Ding Wei

    2013-01-01

    The method of numerical analysis is employed to study the resonance mechanism of the lumped parameter system model for acoustic mine detection. Based on the basic principle of the acoustic resonance technique for mine detection and the characteristics of low-frequency acoustics, the ''soil-mine'' system could be equivalent to a damping ''mass-spring'' resonance model with a lumped parameter analysis method. The dynamic simulation software, Adams, is adopted to analyze the lumped parameter system model numerically. The simulated resonance frequency and anti-resonance frequency are 151 Hz and 512 Hz respectively, basically in agreement with the published resonance frequency of 155 Hz and anti-resonance frequency of 513 Hz, which were measured in the experiment. Therefore, the technique of numerical simulation is validated to have the potential for analyzing the acoustic mine detection model quantitatively. The influences of the soil and mine parameters on the resonance characteristics of the soil—mine system could be investigated by changing the parameter setup in a flexible manner. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  18. Perceptual and acoustic analysis of lexical stress in Greek speakers with dysarthria.

    Science.gov (United States)

    Papakyritsis, Ioannis; Müller, Nicole

    2014-01-01

    The study reported in this paper investigated the abilities of Greek speakers with dysarthria to signal lexical stress at the single word level. Three speakers with dysarthria and two unimpaired control participants were recorded completing a repetition task of a list of words consisting of minimal pairs of Greek disyllabic words contrasted by lexical stress location only. Fourteen listeners were asked to determine the attempted stress location for each word pair. Acoustic analyses of duration and intensity ratios, both within and across words, were undertaken to identify possible acoustic correlates of the listeners' judgments concerning stress location. Acoustic and perceptual data indicate that while each participant with dysarthria in this study had some difficulty in signaling stress unambiguously, the pattern of difficulty was different for each speaker. Further, it was found that the relationship between the listeners' judgments of stress location and the acoustic data was not conclusive.

  19. Autonomous Acoustic Receiver System

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Collects underwater acoustic data and oceanographic data. Data are recorded onboard an ocean buoy and can be telemetered to a remote ship or shore station...

  20. Apparatus for ultrasonic visualization in sodium (VISUS) and acoustic detection in the Phenix reactor

    International Nuclear Information System (INIS)

    Lions, M.; Berger, R.; Bret, A.; Buis, H.; Barton, J.

    A description is given of two acoustic monitoring systems studied at the Fast Neutron Reactor Department at CEN/Cadarache and used in the Phenix reactor. The first is the active type, and the second, passive. The active apparatus is based on the sonar principle and permits visualizing objects inside a reactor tank, especially the heads of assemblies during handling. The passive apparatus, the acoustic detector, observes the reactor core by analyzing the acoustic noise produced in the reactor core. The electroacoustic converters are in both cases located outside, and the acoustic vibrations are transmitted by wave guides. The two pieces of apparatus can operate in a hostile environment, such as liquid metal at high temperature in the presence of high neutron and gamma fluxes

  1. Application of acoustic leak detection technology for the detection and location of leaks in light water reactors

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Prine, D.; Mathieson, T.

    1988-10-01

    This report presents the results of a study to evaluate the adequacy of leak detection systems in light water reactors. The sources of numerous reported leaks and methods of detection have been documented. Research to advance the state of the art of acoustic leak detection is presented, and procedures for implementation are discussed. 14 refs., 70 figs., 10 tabs

  2. Acousto-plasmofluidics: Acoustic modulation of surface plasmon resonance in microfluidic systems

    Directory of Open Access Journals (Sweden)

    Daniel Ahmed

    2015-09-01

    Full Text Available We acoustically modulated the localized surface plasmon resonances (LSPRs of metal nanostructures integrated within microfluidic systems. An acoustically driven micromixing device based on bubble microstreaming quickly and homogeneously mixes multiple laminar flows of different refractive indices. The altered refractive index of the mixed fluids enables rapid modulation of the LSPRs of gold nanodisk arrays embedded within the microfluidic channel. The device features fast response for dynamic operation, and the refractive index within the channel is tailorable. With these unique features, our “acousto-plasmofluidic” device can be useful in applications such as optical switches, modulators, filters, biosensors, and lab-on-a-chip systems.

  3. Development of an acoustic steam generator leak detection system using delay-and-sum beamformer

    International Nuclear Information System (INIS)

    Chikazawa, Yoshitaka

    2009-01-01

    A new acoustic steam generator leak detection system using delay-and-sum beamformer is proposed. The major advantage of the delay-and-sum beamformer is it could provide information of acoustic source direction. An acoustic source of a sodium-water reaction is supposed to be localized while the background noise of the steam generator operation is uniformly distributed in the steam generator tube region. Therefore the delay-and-sum beamformer could distinguish the acoustic source of the sodium-water reaction from steam generator background noise. In this paper, results from numerical analyses are provided to show fundamental feasibility of the new method. (author)

  4. Leak detection in gas pipeline by acoustic and signal processing - A review

    Science.gov (United States)

    Adnan, N. F.; Ghazali, M. F.; Amin, M. M.; Hamat, A. M. A.

    2015-12-01

    The pipeline system is the most important part in media transport in order to deliver fluid to another station. The weak maintenance and poor safety will contribute to financial losses in term of fluid waste and environmental impacts. There are many classifications of techniques to make it easier to show their specific method and application. This paper's discussion about gas leak detection in pipeline system using acoustic method will be presented in this paper. The wave propagation in the pipeline is a key parameter in acoustic method when the leak occurs and the pressure balance of the pipe will generated by the friction between wall in the pipe. The signal processing is used to decompose the raw signal and show in time- frequency. Findings based on the acoustic method can be used for comparative study in the future. Acoustic signal and HHT is the best method to detect leak in gas pipelines. More experiments and simulation need to be carried out to get the fast result of leaking and estimation of their location.

  5. Design and Instrumentation of a Measurement and Calibration System for an Acoustic Telemetry System

    Directory of Open Access Journals (Sweden)

    Zhiqun Deng

    2010-03-01

    Full Text Available The Juvenile Salmon Acoustic Telemetry System (JSATS is an active sensing technology developed by the U.S. Army Corps of Engineers, Portland District, for detecting and tracking small fish. It is used primarily for evaluating behavior and survival of juvenile salmonids migrating through the Federal Columbia River Power System to the Pacific Ocean. It provides critical data for salmon protection and development of more “fish-friendly” hydroelectric facilities. The objective of this study was to design and build a Measurement and Calibration System (MCS for evaluating the JSATS components, because the JSATS requires comprehensive acceptance and performance testing in a controlled environment before it is deployed in the field. The MCS consists of a reference transducer, a water test tank lined with anechoic material, a motion control unit, a reference receiver, a signal conditioner and amplifier unit, a data acquisition board, MATLAB control and analysis interface, and a computer. The fully integrated MCS has been evaluated successfully at various simulated distances and using different encoded signals at frequencies within the bandwidth of the JSATS transmitter. The MCS provides accurate acoustic mapping capability in a controlled environment and automates the process that allows real-time measurements and evaluation of the piezoelectric transducers, sensors, or the acoustic fields. The MCS has been in use since 2009 for acceptance and performance testing of, and further improvements to, the JSATS.

  6. Influence of viscoelastic property on laser-generated surface acoustic waves in coating-substrate systems

    International Nuclear Information System (INIS)

    Sun Hongxiang; Zhang Shuyi; Xu Baiqiang

    2011-01-01

    Taking account of the viscoelasticity of materials, the pulsed laser generation of surface acoustic waves in coating-substrate systems has been investigated quantitatively by using the finite element method. The displacement spectra of the surface acoustic waves have been calculated in frequency domain for different coating-substrate systems, in which the viscoelastic properties of the coatings and substrates are considered separately. Meanwhile, the temporal displacement waveforms have been obtained by applying inverse fast Fourier transforms. The numerical results of the normal surface displacements are presented for different configurations: a single plate, a slow coating on a fast substrate, and a fast coating on a slow substrate. The influences of the viscoelastic properties of the coating and the substrate on the attenuation of the surface acoustic waves have been studied. In addition, the influence of the coating thickness on the attenuation of the surface acoustic waves has been also investigated in detail.

  7. Acoustic concentration of particles in fluid flow

    Science.gov (United States)

    Ward, Michael D.; Kaduchak, Gregory

    2010-11-23

    An apparatus for acoustic concentration of particles in a fluid flow includes a substantially acoustically transparent membrane and a vibration generator that define a fluid flow path therebetween. The fluid flow path is in fluid communication with a fluid source and a fluid outlet and the vibration generator is disposed adjacent the fluid flow path and is capable of producing an acoustic field in the fluid flow path. The acoustic field produces at least one pressure minima in the fluid flow path at a predetermined location within the fluid flow path and forces predetermined particles in the fluid flow path to the at least one pressure minima.

  8. Acoustic concentration of particles in fluid flow

    Science.gov (United States)

    Ward, Michael W.; Kaduchak, Gregory

    2017-08-15

    Disclosed herein is a acoustic concentration of particles in a fluid flow that includes a substantially acoustically transparent membrane and a vibration generator that define a fluid flow path therebetween. The fluid flow path is in fluid communication with a fluid source and a fluid outlet and the vibration generator is disposed adjacent the fluid flow path and is capable of producing an acoustic field in the fluid flow path. The acoustic field produces at least one pressure minima in the fluid flow path at a predetermined location within the fluid flow path and forces predetermined particles in the fluid flow path to the at least one pressure minima.

  9. Development of an Acoustic Localization Method for Cavitation Experiments in Reverberant Environments

    Science.gov (United States)

    Ranjeva, Minna; Thompson, Lee; Perlitz, Daniel; Bonness, William; Capone, Dean; Elbing, Brian

    2011-11-01

    Cavitation is a major concern for the US Navy since it can cause ship damage and produce unwanted noise. The ability to precisely locate cavitation onset in laboratory scale experiments is essential for proper design that will minimize this undesired phenomenon. Measuring the cavitation onset is more accurately determined acoustically than visually. However, if other parts of the model begin to cavitate prior to the component of interest the acoustic data is contaminated with spurious noise. Consequently, cavitation onset is widely determined by optically locating the event of interest. The current research effort aims at developing an acoustic localization scheme for reverberant environments such as water tunnels. Currently cavitation bubbles are being induced in a static water tank with a laser, allowing the localization techniques to be refined with the bubble at a known location. The source is located with the use of acoustic data collected with hydrophones and analyzed using signal processing techniques. To verify the accuracy of the acoustic scheme, the events are simultaneously monitored visually with the use of a high speed camera. Once refined testing will be conducted in a water tunnel. This research was sponsored by the Naval Engineering Education Center (NEEC).

  10. Acoustic Performance of a Real-Time Three-Dimensional Sound-Reproduction System

    Science.gov (United States)

    Faller, Kenneth J., II; Rizzi, Stephen A.; Aumann, Aric R.

    2013-01-01

    The Exterior Effects Room (EER) is a 39-seat auditorium at the NASA Langley Research Center and was built to support psychoacoustic studies of aircraft community noise. The EER has a real-time simulation environment which includes a three-dimensional sound-reproduction system. This system requires real-time application of equalization filters to compensate for spectral coloration of the sound reproduction due to installation and room effects. This paper describes the efforts taken to develop the equalization filters for use in the real-time sound-reproduction system and the subsequent analysis of the system s acoustic performance. The acoustic performance of the compensated and uncompensated sound-reproduction system is assessed for its crossover performance, its performance under stationary and dynamic conditions, the maximum spatialized sound pressure level it can produce from a single virtual source, and for the spatial uniformity of a generated sound field. Additionally, application examples are given to illustrate the compensated sound-reproduction system performance using recorded aircraft flyovers

  11. Fluid dynamics of acoustic and hydrodynamic cavitation in hydraulic power systems

    OpenAIRE

    Ferrari, A.

    2017-01-01

    Cavitation is the transition from a liquid to a vapour phase, due to a drop in pressure to the level of the vapour tension of the fluid. Two kinds of cavitation have been reviewed here: acoustic cavitation and hydrodynamic cavitation. As acoustic cavitation in engineering systems is related to the propagation of waves through a region subjected to liquid vaporization, the available expressions of the sound speed are discussed. One of the main effects of hydrodynamic cavitation in the nozzles ...

  12. Acoustic techniques in nuclear safeguards

    International Nuclear Information System (INIS)

    Olinger, C.T.; Sinha, D.N.

    1995-01-01

    Acoustic techniques can be employed to address many questions relevant to current nuclear technology needs. These include establishing and monitoring intrinsic tags and seals, locating holdup in areas where conventional radiation-based measurements have limited capability, process monitoring, monitoring containers for corrosion or changes in pressure, and facility design verification. These acoustics applications are in their infancy with respect to safeguards and nuclear material management, but proof-of-principle has been demonstrated in many of the areas listed

  13. Bio-inspired UAV routing, source localization, and acoustic signature classification for persistent surveillance

    Science.gov (United States)

    Burman, Jerry; Hespanha, Joao; Madhow, Upamanyu; Pham, Tien

    2011-06-01

    A team consisting of Teledyne Scientific Company, the University of California at Santa Barbara and the Army Research Laboratory* is developing technologies in support of automated data exfiltration from heterogeneous battlefield sensor networks to enhance situational awareness for dismounts and command echelons. Unmanned aerial vehicles (UAV) provide an effective means to autonomously collect data from a sparse network of unattended ground sensors (UGSs) that cannot communicate with each other. UAVs are used to reduce the system reaction time by generating autonomous collection routes that are data-driven. Bio-inspired techniques for search provide a novel strategy to detect, capture and fuse data. A fast and accurate method has been developed to localize an event by fusing data from a sparse number of UGSs. This technique uses a bio-inspired algorithm based on chemotaxis or the motion of bacteria seeking nutrients in their environment. A unique acoustic event classification algorithm was also developed based on using swarm optimization. Additional studies addressed the problem of routing multiple UAVs, optimally placing sensors in the field and locating the source of gunfire at helicopters. A field test was conducted in November of 2009 at Camp Roberts, CA. The field test results showed that a system controlled by bio-inspired software algorithms can autonomously detect and locate the source of an acoustic event with very high accuracy and visually verify the event. In nine independent test runs of a UAV, the system autonomously located the position of an explosion nine times with an average accuracy of 3 meters. The time required to perform source localization using the UAV was on the order of a few minutes based on UAV flight times. In June 2011, additional field tests of the system will be performed and will include multiple acoustic events, optimal sensor placement based on acoustic phenomenology and the use of the International Technology Alliance (ITA

  14. The Influence of the Density of Coconut Fiber as Stack in Thermo-Acoustics Refrigeration System

    Science.gov (United States)

    Hartulistiyoso, E.; Yulianto, M.; Sucahyo, L.

    2018-05-01

    An experimental study of using coconut fiber as stack with varying density in thermo-acoustics refrigeration system has been done. Stack is a device which is described as the “heart” in thermo-acoustics refrigeration system. The length of stack is a fix parameter in this experiment. The performance of the coconut fiber was evaluated from the density of stack (varied from 30%, 50% and 70%), position of stack (varied from 0 to 34 cm from the sound generator), and frequency of sound generator (varied from 150 Hz, 200Hz, 250Hz and 300Hz). The inside, outside, and environment temperatures were collected every second using Data Acquisition (DAQ). The result showed that the increase of stack density will increase the performance of thermo-acoustics refrigeration system. The higher density produced temperature differences in cold side and hot side of 5.4°C. In addition, the position of stack and frequency of sound generator have an important role in the performance of thermo-acoustics refrigeration system for all variations of the density.

  15. Thermal-Acoustic Fatigue of a Multilayer Thermal Protection System in Combined Extreme Environments

    Directory of Open Access Journals (Sweden)

    Liu Liu

    2014-06-01

    Full Text Available In order to ensure integrity of thermal protection system (TPS structure for hypersonic vehicles exposed to severe operating environments, a study is undertaken to investigate the response and thermal-acoustic fatigue damage of a representative multilayer TPS structure under combined thermal and acoustic loads. An unsteady-state flight of a hypersonic vehicle is composed of a series of steady-state snapshots, and for each snapshot an acoustic load is imposed to a static steady-state TPS structure. A multistep thermal-acoustic fatigue damage intensity analysis procedure is given and consists of a heat transfer analysis, a nonlinear thermoelastic analysis, and a random response analysis under a combined loading environment and the fatigue damage intensity has been evaluated with two fatigue analysis techniques. The effects of thermally induced deterministic stress and nondeterministic dynamic stress due to the acoustic loading have been considered in the damage intensity estimation with a maximum stress fatigue model. The results show that the given thermal-acoustic fatigue intensity estimation procedure is a viable approach for life prediction of TPS structures under a typical mission cycle with combined loadings characterized by largely different time-scales. A discussion of the effects of the thermal load, the acoustic load, and fatigue analysis methodology on the fatigue damage intensity has been provided.

  16. FEATURES OF ELECTROMECHANICAL ACOUSTIC ENERGY CONVERSION BY CYLINDRICAL PIEZOCERAMIC TRANSDUCERS WITH INTERNAL SCREENS IN COMPOSITION OF FLAT SYSTEMS

    Directory of Open Access Journals (Sweden)

    A. G. Leiko

    2018-01-01

    Full Text Available The problem of sound emission is considered by a system formed from cylindrical piezoceramic radiators with internal acoustically soft screens. Longitudinal axis of emitters lie in one plane. This system is characterized by the interaction of electric, mechanical and acoustic fields in the process of conversion electrical energy to acoustical energy and acoustic fields in the process of forming them in the environments. The purpose of the work is to determine the peculiarities of the electromechanical acoustic transformation of energy by cylindrical piezoceramic radiators with internal screens in the composition of flat systems, taking into account all types of interaction.The research was carried out by the method of bound fields in multiply connected domains with the use of addition theorems for the cylindrical wave functions. The physical fields arising from the emission of sound by such a system are determined by the joint solution of the system of differential equations: the wave equation; equations of motion of thin piezoceramic shells with circular polarization in displacements; the equations of forced electrostatics for piezoceramics at given boundary conditions, the conditions of conjugation of fields at the boundaries of the division of domains and electric conditions.The solution of the problem is reduced to the solution of an infinite system of linear algebraic equations with respect to unknown coefficients of field expansions.An analysis of the results of numerical calculations, performed on the basis of the obtained analytical relations, called to establish a number of features in the electromechanical acoustic transformation of energy by emitters in the composition of flat systems. They include: the role of acoustic interaction in the process of energy conversion; determination of the mechanism of quantitative assessment of the influence of interaction on these processes; the dependence of the degree of violation of the radial

  17. Wireless Damage Location Sensing System

    Science.gov (United States)

    Woodard, Stanley E. (Inventor); Taylor, Bryant Douglas (Inventor)

    2012-01-01

    A wireless damage location sensing system uses a geometric-patterned wireless sensor that resonates in the presence of a time-varying magnetic field to generate a harmonic response that will experience a change when the sensor experiences a change in its geometric pattern. The sensing system also includes a magnetic field response recorder for wirelessly transmitting the time-varying magnetic field and for wirelessly detecting the harmonic response. The sensing system compares the actual harmonic response to a plurality of predetermined harmonic responses. Each predetermined harmonic response is associated with a severing of the sensor at a corresponding known location thereof so that a match between the actual harmonic response and one of the predetermined harmonic responses defines the known location of the severing that is associated therewith.

  18. Opto-acoustic technique to evaluate adhesion strength of thin-film systems

    Directory of Open Access Journals (Sweden)

    S. Yoshida

    2012-06-01

    Full Text Available An opto-acoustic technique is proposed to evaluate the adhesion strength of thin film systems at the film-substrate interface. The thin-film system to be examined is configured as an end-mirror of a Michelson interferometer, and driven from the rear with an acoustic transducer at audible frequencies. The amplitude of the resultant oscillation of the film is quantified as the variation in the contrast of the interferometric fringe pattern observed with a digital camera at 30 frames/s. As a proof of concept, experiment has been conducted with the use of a pair of strongly and weakly adhered Au-coated Si-wafer specimens. The technique successfully differentiates the adhesion strength of the specimens.

  19. Multimodal location estimation of videos and images

    CERN Document Server

    Friedland, Gerald

    2015-01-01

    This book presents an overview of the field of multimodal location estimation, i.e. using acoustic, visual, and/or textual cues to estimate the shown location of a video recording. The authors' sample research results in this field in a unified way integrating research work on this topic that focuses on different modalities, viewpoints, and applications. The book describes fundamental methods of acoustic, visual, textual, social graph, and metadata processing as well as multimodal integration methods used for location estimation. In addition, the text covers benchmark metrics and explores the limits of the technology based on a human baseline. ·         Discusses localization of multimedia data; ·         Examines fundamental methods of establishing location metadata for images and videos (other than GPS tagging); ·         Covers Data-Driven as well as Semantic Location Estimation.

  20. CCS, locations and asynchronous transition systems

    DEFF Research Database (Denmark)

    Mukund, Madhavan; Nielsen, Mogens

    1992-01-01

    We provide a simple non-interleaved operational semantics for CCS in terms of asynchronous transition systems. We identify the concurrency present in the system in a natural way, in terms of events occurring at independent locations in the system. We extend the standard interleaving transition...... system for CCS by introducing labels on the transitions with information about the locations of events. We then show that the resulting transition system is an asynchronous transition system which has the additional property of being elementary, which means that it can also be represented by a 1-safe net....... We also introduce a notion of bisimulation on asynchronous transition systems which preserves independence. We conjecture that the induced equivalence on CCS processes coincides with the notion of location equivalence proposed by Boudol et al....

  1. Characterization of acoustic emission signals generated by water flow through intergranular stress corrosion cracks

    International Nuclear Information System (INIS)

    Claytor, T.N.; Kupperman, D.S.

    1985-05-01

    A program is under way at Argonne National Laboratory (ANL) to develop an independent capability to assess the effectiveness of current and proposed techniques for acoustic leak detection (ALD) in reactor coolant systems. The program will establish whether meaningful quantitative data on flow rates and leak location can be obtained from acoustic signatures of leaks due to intergranular stress corrosion cracks (TGSCCs) and fatigue cracks, and whether these can be distinguished from other types of leaks. 5 refs., 3 figs

  2. Microcontroller-based underwater acoustic ECG telemetry system.

    Science.gov (United States)

    Istepanian, R S; Woodward, B

    1997-06-01

    This paper presents a microcontroller-based underwater acoustic telemetry system for digital transmission of the electrocardiogram (ECG). The system is designed for the real time, through-water transmission of data representing any parameter, and it was used initially for transmitting in multiplexed format the heart rate, breathing rate and depth of a diver using self-contained underwater breathing apparatus (SCUBA). Here, it is used to monitor cardiovascular reflexes during diving and swimming. The programmable capability of the system provides an effective solution to the problem of transmitting data in the presence of multipath interference. An important feature of the paper is a comparative performance analysis of two encoding methods, Pulse Code Modulation (PCM) and Pulse Position Modulation (PPM).

  3. A hybrid SEA/modal technique for modeling structural-acoustic interior noise in rotorcraft.

    Science.gov (United States)

    Jayachandran, V; Bonilha, M W

    2003-03-01

    This paper describes a hybrid technique that combines Statistical Energy Analysis (SEA) predictions for structural vibration with acoustic modal summation techniques to predict interior noise levels in rotorcraft. The method was applied for predicting the sound field inside a mock-up of the interior panel system of the Sikorsky S-92 helicopter. The vibration amplitudes of the frame and panel systems were predicted using a detailed SEA model and these were used as inputs to the model of the interior acoustic space. The spatial distribution of the vibration field on individual panels, and their coupling to the acoustic space were modeled using stochastic techniques. Leakage and nonresonant transmission components were accounted for using space-averaged values obtained from a SEA model of the complete structural-acoustic system. Since the cabin geometry was quite simple, the modeling of the interior acoustic space was performed using a standard modal summation technique. Sound pressure levels predicted by this approach at specific microphone locations were compared with measured data. Agreement within 3 dB in one-third octave bands above 40 Hz was observed. A large discrepancy in the one-third octave band in which the first acoustic mode is resonant (31.5 Hz) was observed. Reasons for such a discrepancy are discussed in the paper. The developed technique provides a method for modeling helicopter cabin interior noise in the frequency mid-range where neither FEA nor SEA is individually effective or accurate.

  4. Acoustic glitches in solar-type stars from Kepler

    DEFF Research Database (Denmark)

    Mazumdar, A.; Monteiro, M. J. P. F. G.; Ballot, J

    2012-01-01

    We report the measurement of the acoustic locations of layers of sharp variation in sound speed in the interiors of 19 solar-type stars observed by the Kepler mission. The oscillatory signal in the frequencies arising due to the acoustic glitches at the base of the convection zone and the second...

  5. Acoustic calibration for the KM3NeT pre-production module

    Energy Technology Data Exchange (ETDEWEB)

    Enzenhöfer, A., E-mail: alexander.enzenhoefer@physik.uni-erlangen.de [Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, D-91058 Erlangen (Germany)

    2013-10-11

    The proposed large scale Cherenkov neutrino telescope KM3NeT will carry photo-sensors on flexible structures, the detection units. The Mediterranean Sea, where KM3NeT will be installed, constitutes a highly dynamic environment in which the detection units are constantly in motion. Thus it is necessary to monitor the exact sensor positions continuously to achieve the desired resolution for the neutrino telescope. A common way to perform this monitoring is the use of acoustic positioning systems with emitters and receivers based on the piezoelectric effect. The acoustic receivers are attached to detection units whereas the emitters are located at known positions on the sea floor. There are complete commercial systems for this application with sufficient precision. But these systems are limited in the use of their data and inefficient as they were designed to perform only this single task. Several working groups in the KM3NeT consortium are cooperating to custom-design a positioning system for the specific requirements of KM3NeT. Most of the studied solutions hold the possibility to extend the application area from positioning to additional tasks like acoustic particle detection or monitoring of the deep-sea acoustic environment. The KM3NeT Pre-Production Module (PPM) is a test system to verify the correct operation and interoperability of the major involved hardware and software components developed for KM3NeT. In the context of the PPM, alternative designs of acoustic sensors including small piezoelectric elements equipped with preamplifiers inside the same housing as the optical sensors will be tested. These will be described in this article.

  6. Artificial defects detection and location during welding

    International Nuclear Information System (INIS)

    Asty, M.

    1978-01-01

    Welding control by acoustic emission allows defects detection as soon as they are created. Acoustic testing saves time and gives better quality assurance in the case of multiple pass welding of plates. A welded joint was performed on A533B steel plates 250 mm thick by submerged arc welding. Artificial defects were implanted to determine significative parameters of acoustic reception. In operating conditions a significant acoustic activity takes place only during welding as shown by preliminary tests. At the same time an important noise is created by the arc, scories cooling and metal solidification and cooling. These problems are solved by an original processing in time-space detecting and locating defects with a good approximation [fr

  7. Feasibility of evaluating the integrity of FTR duct to end fixture welds using acoustic emission monitoring

    International Nuclear Information System (INIS)

    Trantow, R.L.

    1975-11-01

    A method of applying real-time acoustic emission (AE) source location to evaluate the integrity of duct-to-end fixture welds was developed and evaluated using the HEDL R8-4 AE monitor coupled with a PDP-8e minicomputer. Operational software was developed to control the system's data acquisition, storage, and display functions. Performance was evaluated on the basis of comparisons between AE source location data and subsequent destructive examination of six duct-to-transition ring qualification welds. Ten separate discontinuities seen in the metallography performed at 35 locations along these welds correlated with the averaged acoustic emission activity revealed by the AE source location maps. This relationship is not presently considered to be usable as a system calibration method however, because of the limited range of discontinuity lengths (from 0.0003 to 0.004 in. long) that were correlated. The presence of six other discontinuities, found in regions showing low levels of emission activity, indicated that significant stress risers can go undetected under the conditions investigated

  8. Application of acoustic agglomeration to enhance air filtration efficiency in air-conditioning and mechanical ventilation (ACMV) systems.

    Science.gov (United States)

    Ng, Bing Feng; Xiong, Jin Wen; Wan, Man Pun

    2017-01-01

    The recent episodes of haze in Southeast Asia have caused some of the worst regional atmospheric pollution ever recorded in history. In order to control the levels of airborne fine particulate matters (PM) indoors, filtration systems providing high PM capturing efficiency are often sought, which inadvertently also results in high airflow resistance (or pressure drop) that increases the energy consumption for air distribution. A pre-conditioning mechanism promoting the formation of particle clusters to enhance PM capturing efficiency without adding flow resistance in the air distribution ductwork could provide an energy-efficient solution. This pre-conditioning mechanism can be fulfilled by acoustic agglomeration, which is a phenomenon that promotes the coagulation of suspended particles by acoustic waves propagating in the fluid medium. This paper discusses the basic mechanisms of acoustic agglomeration along with influencing factors that could affect the agglomeration efficiency. The feasibility to apply acoustic agglomeration to improve filtration in air-conditioning and mechanical ventilation (ACMV) systems is investigated experimentally in a small-scale wind tunnel. Experimental results indicate that this novel application of acoustic pre-conditioning improves the PM2.5 filtration efficiency of the test filters by up to 10% without introducing additional pressure drop. The fan energy savings from not having to switch to a high capturing efficiency filter largely outstrip the additional energy consumed by the acoustics system. This, as a whole, demonstrates potential energy savings from the combined acoustic-enhanced filtration system without compromising on PM capturing efficiency.

  9. Application of acoustic agglomeration to enhance air filtration efficiency in air-conditioning and mechanical ventilation (ACMV systems.

    Directory of Open Access Journals (Sweden)

    Bing Feng Ng

    Full Text Available The recent episodes of haze in Southeast Asia have caused some of the worst regional atmospheric pollution ever recorded in history. In order to control the levels of airborne fine particulate matters (PM indoors, filtration systems providing high PM capturing efficiency are often sought, which inadvertently also results in high airflow resistance (or pressure drop that increases the energy consumption for air distribution. A pre-conditioning mechanism promoting the formation of particle clusters to enhance PM capturing efficiency without adding flow resistance in the air distribution ductwork could provide an energy-efficient solution. This pre-conditioning mechanism can be fulfilled by acoustic agglomeration, which is a phenomenon that promotes the coagulation of suspended particles by acoustic waves propagating in the fluid medium. This paper discusses the basic mechanisms of acoustic agglomeration along with influencing factors that could affect the agglomeration efficiency. The feasibility to apply acoustic agglomeration to improve filtration in air-conditioning and mechanical ventilation (ACMV systems is investigated experimentally in a small-scale wind tunnel. Experimental results indicate that this novel application of acoustic pre-conditioning improves the PM2.5 filtration efficiency of the test filters by up to 10% without introducing additional pressure drop. The fan energy savings from not having to switch to a high capturing efficiency filter largely outstrip the additional energy consumed by the acoustics system. This, as a whole, demonstrates potential energy savings from the combined acoustic-enhanced filtration system without compromising on PM capturing efficiency.

  10. Occupant satisfaction with the acoustical environment : green office buildings before and after treatment

    Energy Technology Data Exchange (ETDEWEB)

    Hodgson, M. [British Columbia Univ., Vancouver, BC (Canada). School of Occupational and Environmental Hygiene, Acoustics and Noise Research Group

    2009-07-01

    Sustainable architecture is meant to preserve the environment and conserve natural resources, as well as provide an environment for the occupants that promotes wellbeing and productivity. Occupants generally claim that the acoustical environment is the least satisfactory aspect of green office buildings. They are dissatisfied with excessive noise and poor speech privacy. This paper reported on the results of 2 studies of the acoustical environments in green office buildings before and after acoustical-control measures were installed. Acoustical quality was evaluated by occupant-satisfaction surveys and acoustical-parameter measurements. The first study, which involved 6 green office buildings, showed that buildings designed to obtain LEED ratings are unlikely to have satisfactory acoustical environments. A naturally-ventilated, green university building with a poor acoustical environment was examined in the second study. The results of this study suggest that improving acoustical environments in green buildings requires good acoustical design, with input from an acoustical specialist from the beginning of the design process. The design should consider site selection and building orientation; external envelope and penetrations in it; building layout and internal partitions; HVAC systems; appropriate dimensioning of spaces; and the amount and location of sound absorbing treatments. The study also showed that a building's energy efficiency, lighting, ventilation, air-quality and acoustics are interconnected, and that no aspect can be successfully designed in isolation. It was concluded that optimized engineering-control measures can improve poor acoustical environments. 11 refs., 1 tab., 1 fig.

  11. Acoustic array systems theory, implementation, and application

    CERN Document Server

    Bai, Mingsian R; Benesty, Jacob

    2013-01-01

    Presents a unified framework of far-field and near-field array techniques for noise source identification and sound field visualization, from theory to application. Acoustic Array Systems: Theory, Implementation, and Application provides an overview of microphone array technology with applications in noise source identification and sound field visualization. In the comprehensive treatment of microphone arrays, the topics covered include an introduction to the theory, far-field and near-field array signal processing algorithms, practical implementations, and common applic

  12. Acoustic event location and background noise characterization on a free flying infrasound sensor network in the stratosphere

    Science.gov (United States)

    Bowman, Daniel C.; Albert, Sarah A.

    2018-06-01

    A variety of Earth surface and atmospheric sources generate low-frequency sound waves that can travel great distances. Despite a rich history of ground-based sensor studies, very few experiments have investigated the prospects of free floating microphone arrays at high altitudes. However, recent initiatives have shown that such networks have very low background noise and may sample an acoustic wave field that is fundamentally different than that at Earth's surface. The experiments have been limited to at most two stations at altitude, making acoustic event detection and localization difficult. We describe the deployment of four drifting microphone stations at altitudes between 21 and 24 km above sea level. The stations detected one of two regional ground-based chemical explosions as well as the ocean microbarom while travelling almost 500 km across the American Southwest. The explosion signal consisted of multiple arrivals; signal amplitudes did not correlate with sensor elevation or source range. The waveforms and propagation patterns suggest interactions with gravity waves at 35-45 km altitude. A sparse network method that employed curved wave front corrections was able to determine the backazimuth from the free flying network to the acoustic source. Episodic signals similar to those seen on previous flights in the same region were noted, but their source remains unclear. Background noise levels were commensurate with those on infrasound stations in the International Monitoring System below 2 s.

  13. Passive acoustic monitoring to detect spawning in large-bodied catostomids

    Science.gov (United States)

    Straight, Carrie A.; Freeman, Byron J.; Freeman, Mary C.

    2014-01-01

    Documenting timing, locations, and intensity of spawning can provide valuable information for conservation and management of imperiled fishes. However, deep, turbid or turbulent water, or occurrence of spawning at night, can severely limit direct observations. We have developed and tested the use of passive acoustics to detect distinctive acoustic signatures associated with spawning events of two large-bodied catostomid species (River Redhorse Moxostoma carinatum and Robust Redhorse Moxostoma robustum) in river systems in north Georgia. We deployed a hydrophone with a recording unit at four different locations on four different dates when we could both record and observe spawning activity. Recordings captured 494 spawning events that we acoustically characterized using dominant frequency, 95% frequency, relative power, and duration. We similarly characterized 46 randomly selected ambient river noises. Dominant frequency did not differ between redhorse species and ranged from 172.3 to 14,987.1 Hz. Duration of spawning events ranged from 0.65 to 11.07 s, River Redhorse having longer durations than Robust Redhorse. Observed spawning events had significantly higher dominant and 95% frequencies than ambient river noises. We additionally tested software designed to automate acoustic detection. The automated detection configurations correctly identified 80–82% of known spawning events, and falsely indentified spawns 6–7% of the time when none occurred. These rates were combined over all recordings; rates were more variable among individual recordings. Longer spawning events were more likely to be detected. Combined with sufficient visual observations to ascertain species identities and to estimate detection error rates, passive acoustic recording provides a useful tool to study spawning frequency of large-bodied fishes that displace gravel during egg deposition, including several species of imperiled catostomids.

  14. Development of high sensitivity eight-element multiplexed fiber laser acoustic pressure hydrophone array and interrogation system

    Science.gov (United States)

    Li, Ming; Sun, Zhihui; Zhang, Xiaolei; Li, Shujuan; Song, Zhiqiang; Wang, Meng; Guo, Jian; Ni, Jiasheng; Wang, Chang; Peng, Gangding; Xu, Xiangang

    2017-09-01

    Fiber laser hydrophones have got widespread concerns due to the unique advantages and broad application prospects. In this paper, the research results of the eight-element multiplexed fiber laser acoustic pressure array and the interrogation system are introduced, containing low-noise distributed feedback fiber laser (DFB-FL) fabrication, sensitivity enhancement packaging, and interferometric signal demodulation. The frequency response range of the system is 10Hz-10kHz, the laser frequency acoustic pressure sensitivity reaches 115 dB re Hz/Pa, and the equivalent noise acoustic pressure is less than 60μPa/Hz1/2. The dynamic range of the system is greater than 120 dB.

  15. Optimization strategy for actuator and sensor placement in active structural acoustic control

    NARCIS (Netherlands)

    Oude nijhuis, M.H.H.; de Boer, Andries

    2003-01-01

    In active structural acoustic control the goal is to reduce the sound radiation of a structure by means of changing the vibrational behaviour of that structure. The performance of such an active control system is to a large extent determined by the locations of the actuators and sensors. In this

  16. Acoustic Biometric System Based on Preprocessing Techniques and Linear Support Vector Machines.

    Science.gov (United States)

    del Val, Lara; Izquierdo-Fuente, Alberto; Villacorta, Juan J; Raboso, Mariano

    2015-06-17

    Drawing on the results of an acoustic biometric system based on a MSE classifier, a new biometric system has been implemented. This new system preprocesses acoustic images, extracts several parameters and finally classifies them, based on Support Vector Machine (SVM). The preprocessing techniques used are spatial filtering, segmentation-based on a Gaussian Mixture Model (GMM) to separate the person from the background, masking-to reduce the dimensions of images-and binarization-to reduce the size of each image. An analysis of classification error and a study of the sensitivity of the error versus the computational burden of each implemented algorithm are presented. This allows the selection of the most relevant algorithms, according to the benefits required by the system. A significant improvement of the biometric system has been achieved by reducing the classification error, the computational burden and the storage requirements.

  17. Acoustic wave simulation using an overset grid for the global monitoring system

    Science.gov (United States)

    Kushida, N.; Le Bras, R.

    2017-12-01

    The International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has been monitoring hydro-acoustic and infrasound waves over the globe. Because of the complex natures of the oceans and the atmosphere, computer simulation can play an important role in understanding the observed signals. In this regard, methods which depend on partial differential equations and require minimum modelling, are preferable. So far, to our best knowledge, acoustic wave propagation simulations based on partial differential equations on such a large scale have not been performed (pp 147 - 161 of ref [1], [2]). The main difficulties in building such simulation codes are: (1) considering the inhomogeneity of medium including background flows, (2) high aspect ratio of computational domain, (3) stability during long time integration. To overcome these difficulties, we employ a two-dimensional finite different (FDM) scheme on spherical coordinates with the Yin-Yang overset grid[3] solving the governing equation of acoustic waves introduces by Ostashev et. al.[4]. The comparison with real recording examples in hydro-acoustic will be presented at the conference. [1] Paul C. Etter: Underwater Acoustic Modeling and Simulation, Fourth Edition, CRC Press, 2013. [2] LIAN WANG et. al.: REVIEW OF UNDERWATER ACOUSTIC PROPAGATION MODELS, NPL Report AC 12, 2014. [3] A. Kageyama and T. Sato: "Yin-Yang grid": An overset grid in spherical geometry, Geochem. Geophys. Geosyst., 5, Q09005, 2004. [4] Vladimir E. Ostashev et. al: Equations for finite-difference, time-domain simulation of sound propagation in moving inhomogeneous media and numerical implementation, Acoustical Society of America. DOI: 10.1121/1.1841531, 2005.

  18. Education in acoustics in Argentina

    Science.gov (United States)

    Miyara, Federico

    2002-11-01

    Over the last decades, education in acoustics (EA) in Argentina has experienced ups and downs due to economic and political issues interfering with long term projects. Unlike other countries, like Chile, where EA has reached maturity in spite of the acoustical industry having shown little development, Argentina has several well-established manufacturers of acoustic materials and equipment but no specific career with a major in acoustics. At the university level, acoustics is taught as a complementary--often elective--course for careers such as architecture, communication engineering, or music. In spite of this there are several research centers with programs covering environmental and community noise, effects of noise on man, acoustic signal processing, musical acoustics and acoustic emission, and several national and international meetings are held each year in which results are communicated and discussed. Several books on a variety of topics such as sound system, architectural acoustics, and noise control have been published as well. Another chapter in EA is technical and vocational education, ranging between secondary and postsecondary levels, with technical training on sound system operation or design. Over the last years there have been several attempts to implement master degrees in acoustics or audio engineering, with little or no success.

  19. Acoustic Communications Measurement Systems (ACOMMS)

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Design and develop adaptive signal processing techniques to improve underwater acoustic communications and networking. Phase coherent and incoherent signal...

  20. Design, fabrication and testing of a 5-Hz acoustic exciter system

    Science.gov (United States)

    Lundy, D. H.; Robinson, G. D.

    1973-01-01

    A 5-Hz acoustic excitation system was designed, fabricated and checked out for use in the modulation of a stagnant gas volume contained in an absorption cell. A detailed system description of the test equipment, both mechanical and electronic, and an operating procedure are included. Conclusions are also presented.

  1. Acoustic comfort in high-school classrooms for students and teachers

    NARCIS (Netherlands)

    G.E. Puglisi; L.C. Cantor Cutiva (Lady Catherine); L. Pavese; A. Castellana; M. Bona; S. Fasolis; V. Lorenzatti; A. Carullo; A. Burdor; F. Bronuzzi; A. Astolfi

    2015-01-01

    textabstractThis work focuses on the evaluation of acoustical quality in high-school classrooms through in-field measurements and self-reports. Two school buildings that differ in location and typology, were considered. In-field measurements included sound insulation, room acoustics and

  2. Photo acoustic imaging: technology, systems and market trends

    Science.gov (United States)

    Faucheux, Marc; d'Humières, Benoît; Cochard, Jacques

    2017-03-01

    Although the Photo Acoustic effect was observed by Graham Bell in 1880, the first applications (gas analysis) occurred in 1970's using the required energetic light pulses from lasers. During mid 1990's medical imaging research begun to use Photo Acoustic effect and in vivo images were obtained in mid-2000. Since 2009, the number of patent related to Photo Acoustic Imaging (PAI) has dramatically increased. PAI machines for pre-clinical and small animal imaging have been being used in a routine way for several years. Based on its very interesting features (non-ionizing radiation, noninvasive, high depth resolution ratio, scalability, moderate price) and because it is able to deliver not only anatomical, but functional and molecular information, PAI is a very promising clinical imaging modality. It penetrates deeper into tissue than OCT (Optical Coherence Tomography) and provides a higher resolution than ultrasounds. The PAI is one of the most growing imaging modality and some innovative clinical systems are planned to be on market in 2017. Our study analyzes the different approaches such as photoacoustic computed tomography, 3D photoacoustic microscopy, multispectral photoacoustic tomography and endoscopy with the recent and tremendous technological progress over the past decade: advances in image reconstruction algorithms, laser technology, ultrasound detectors and miniaturization. We analyze which medical domains and applications are the most concerned and explain what should be the forthcoming medical system in the near future. We segment the market in four parts: Components and R&D, pre-clinical, analytics, clinical. We analyzed what should be, quantitatively and qualitatively, the PAI medical markets in each segment and its main trends. We point out the market accessibility (patents, regulations, clinical evaluations, clinical acceptance, funding). In conclusion, we explain the main market drivers and challenges to overcome and give a road map for medical

  3. Probability of acoustic transmitter detections by receiver lines in Lake Huron: results of multi-year field tests and simulations

    Science.gov (United States)

    Hayden, Todd A.; Holbrook, Christopher M.; Binder, Thomas; Dettmers, John M.; Cooke, Steven J.; Vandergoot, Christopher S.; Krueger, Charles C.

    2016-01-01

    lines in Lake Huron varied across a range of spatiotemporal scales and was inconsistent among receiver lines. Our simulations indicated that if 69 kHz acoustic transmitters operating at 158 dB in 10–30 m of freshwater were being used, then receivers should be placed 1000 m apart to ensure that all fish moving at 1 m s−1 or less will be detected 90% of days over a 2-year period. Whereas these results can be used as general guidelines for designing new studies, the irregular variation in acoustic transmitter detection probabilities we observed among receiver line locations in Lake Huron makes designing receiver lines in similar systems challenging and emphasizes the need to conduct post hoc analyses of acoustic transmitter detection probabilities.

  4. Acoustic lenses

    International Nuclear Information System (INIS)

    Kittmer, C.A.

    1983-03-01

    Acoustic lenses focus ultrasound to produce pencil-like beams with reduced near fields. When fitted to conventional (flat-faced) transducers, such lenses greatly improve the ability to detect and size defects. This paper describes a program developed to design acoustic lenses for use in immersion or contact inspection, using normal or angle beam mode with flat or curved targets. Lens surfaces are circular in geometry to facilitate machining. For normal beam inspection of flat plate, spherical or cylindrical lenses are used. For angle beam or curved surface inspections, a compound lens is required to correct for the extra induced aberration. Such a lens is aspherical with one radius of curvature in the plane of incidence, and a different radius of curvature in the plane perpendicular to the incident plane. The resultant beam profile (i.e., location of the acoustic focus, beam diameter, 6 dB working range) depends on the degree of focusing and the transducer used. The operating frequency and bandwidth can be affected by the instrumentation used. Theoretical and measured beam profiles are in good agreement. Various applications, from zone focusing used for defect sizing in thick plate, to line focusing for pipe weld inspection, are discussed

  5. Tipping point analysis of ocean acoustic noise

    Science.gov (United States)

    Livina, Valerie N.; Brouwer, Albert; Harris, Peter; Wang, Lian; Sotirakopoulos, Kostas; Robinson, Stephen

    2018-02-01

    We apply tipping point analysis to a large record of ocean acoustic data to identify the main components of the acoustic dynamical system and study possible bifurcations and transitions of the system. The analysis is based on a statistical physics framework with stochastic modelling, where we represent the observed data as a composition of deterministic and stochastic components estimated from the data using time-series techniques. We analyse long-term and seasonal trends, system states and acoustic fluctuations to reconstruct a one-dimensional stochastic equation to approximate the acoustic dynamical system. We apply potential analysis to acoustic fluctuations and detect several changes in the system states in the past 14 years. These are most likely caused by climatic phenomena. We analyse trends in sound pressure level within different frequency bands and hypothesize a possible anthropogenic impact on the acoustic environment. The tipping point analysis framework provides insight into the structure of the acoustic data and helps identify its dynamic phenomena, correctly reproducing the probability distribution and scaling properties (power-law correlations) of the time series.

  6. Tipping point analysis of ocean acoustic noise

    Directory of Open Access Journals (Sweden)

    V. N. Livina

    2018-02-01

    Full Text Available We apply tipping point analysis to a large record of ocean acoustic data to identify the main components of the acoustic dynamical system and study possible bifurcations and transitions of the system. The analysis is based on a statistical physics framework with stochastic modelling, where we represent the observed data as a composition of deterministic and stochastic components estimated from the data using time-series techniques. We analyse long-term and seasonal trends, system states and acoustic fluctuations to reconstruct a one-dimensional stochastic equation to approximate the acoustic dynamical system. We apply potential analysis to acoustic fluctuations and detect several changes in the system states in the past 14 years. These are most likely caused by climatic phenomena. We analyse trends in sound pressure level within different frequency bands and hypothesize a possible anthropogenic impact on the acoustic environment. The tipping point analysis framework provides insight into the structure of the acoustic data and helps identify its dynamic phenomena, correctly reproducing the probability distribution and scaling properties (power-law correlations of the time series.

  7. An acoustic pyrometer system for tomographic thermal imaging in power plant boilers

    OpenAIRE

    Bramanti, Mauro; Gray, Antoinia; Pasini, Sauro; Salerno, Emanuele; Tonazzini, Anna

    1994-01-01

    The paper presents an acoustic pyrometry method for the reconstruction of temperature maps inside power plant boilers. It is based on measuring times-of-flight of acoustic waves along a number of straight paths in a cross-section of the boiler; via an integral relationship, these times depend on the temperature of the gaseous medium along the paths. On this basis, 2D temperature maps can be reconstructed using" suitable inversion techniques. The structure of a particular 'system for the measu...

  8. Vibro-acoustic model of an active aircraft cabin window

    Science.gov (United States)

    Aloufi, Badr; Behdinan, Kamran; Zu, Jean

    2017-06-01

    This paper presents modeling and design of an active structural acoustic control (ASAC) system for controlling the low frequency sound field transmitted through an aircraft cabin window. The system uses stacked piezoelectric elements arranged in a manner to generate out-of-plane actuation point forces acting on the window panel boundaries. A theoretical vibro-acoustic model for an active quadruple-panel system is developed to characterize the dynamic behavior of the system and achieve a good understanding of the active control performance and the physical phenomena of the sound transmission loss (STL) characteristics. The quadruple-panel system represents the passenger window design used in some classes of modern aircraft with an exterior double pane of Plexiglas, an interior dust cover pane and a glazed dimmable pane, all separated by thin air cavities. The STL characteristics of identical pane window configurations with different piezoelectric actuator sets are analyzed. A parametric study describes the influence of important active parameters, such as the input voltage, number and location of the actuator elements, on the STL is investigated. In addition, a mathematical model for obtaining the optimal input voltage is developed to improve the acoustic attenuation capability of the control system. In general, the achieved results indicate that the proposed ASAC design offers a considerable improvement in the passive sound loss performance of cabin window design without significant effects, such as weight increase, on the original design. Also, the results show that the acoustic control of the active model with piezoelectric actuators bonded to the dust cover pane generates high structural vibrations in the radiating panel (dust cover) and an increase in sound power radiation. High active acoustic attenuation can be achieved by designing the ASAC system to apply active control forces on the inner Plexiglas panel or dimmable panel by installing the actuators on the

  9. Acoustic emission from thermal-gradient cracks in UO2

    International Nuclear Information System (INIS)

    Kennedy, C.R.; Kupperman, D.S.; Wrona, B.J.

    1975-01-01

    A feasibility study has been conducted to evaluate the potential use of acoustic emission to monitor thermal-shock damage in direct electrical heating of UO 2 pellets. In the apparatus used for the present tests, two acoustic-emission sensors were placed on extensions of the upper and lower electrical feedthroughs. Commercially available equipment was used to accumulate acoustic-emission data. The accumulation of events displayed on a cathode-ray-tube screen indicates the total number of acoustic-emission events at a particular location within the pellet stack. These tests have indicated that acoustic emission can be used to monitor thermal-shock damage in UO 2 pellets subjected to direct-electrical heating. 8 references

  10. Acoustic Emission Beamforming for Detection and Localization of Damage

    Science.gov (United States)

    Rivey, Joshua Callen

    The aerospace industry is a constantly evolving field with corporate manufacturers continually utilizing innovative processes and materials. These materials include advanced metallics and composite systems. The exploration and implementation of new materials and structures has prompted the development of numerous structural health monitoring and nondestructive evaluation techniques for quality assurance purposes and pre- and in-service damage detection. Exploitation of acoustic emission sensors coupled with a beamforming technique provides the potential for creating an effective non-contact and non-invasive monitoring capability for assessing structural integrity. This investigation used an acoustic emission detection device that employs helical arrays of MEMS-based microphones around a high-definition optical camera to provide real-time non-contact monitoring of inspection specimens during testing. The study assessed the feasibility of the sound camera for use in structural health monitoring of composite specimens during tensile testing for detecting onset of damage in addition to nondestructive evaluation of aluminum inspection plates for visualizing stress wave propagation in structures. During composite material monitoring, the sound camera was able to accurately identify the onset and location of damage resulting from large amplitude acoustic feedback mechanisms such as fiber breakage. Damage resulting from smaller acoustic feedback events such as matrix failure was detected but not localized to the degree of accuracy of larger feedback events. Findings suggest that beamforming technology can provide effective non-contact and non-invasive inspection of composite materials, characterizing the onset and the location of damage in an efficient manner. With regards to the nondestructive evaluation of metallic plates, this remote sensing system allows us to record wave propagation events in situ via a single-shot measurement. This is a significant improvement over

  11. Simulation of the electron acoustic instability for a finite-size electron beam system

    International Nuclear Information System (INIS)

    Lin, C.S.; Winske, D.

    1987-01-01

    Satellite observations at midlatitudes (≅20,000 km) near the earth's dayside polar cusp boundary layer indicate that the upward electron beams have a narrow latitudinal width up to 0.1 0 . In the cusp boundary layer where the electron population consists of a finite-size electron beam in a background of uniform cold and hot electrons, the electron acoustic mode is unstable inside the electron beam but damped outside the electron beam. Simulations of the electron acoustic instability for a finite-size beam system are carried out with a particle-in-cell code to investigate the heating phenomena associated with the instability and the width of the heating region. The simulations show that the finite-size electron beam radiates electrostatic electron acoustic waves. The decay length of the electron acoustic waves outside the beam in the simulation agrees with the spatial decay length derived from the linear dispersion equation

  12. Impact location of objects hitting the water surface

    Science.gov (United States)

    Kadri, Usama

    2017-04-01

    Analysis of data, recorded on March 8th 2014 at the Comprehensive Test ban Treaty Organisation's hydroacoustic station off Cape Leeuwin Western Australia, reveal pressure signatures of objects impacting at the sea surface which could be associated with falling meteorites as well as the missing Malaysian MH370 airplane. The location of the sources are identified analytically by an inverse solution based on acoustic-gravity wave theory (e.g. see references below) which have been developed and validated experimentally. Apart from the direct contribution to the search efforts after the missing airplane, the method we describe here is very efficient for identifying the location of sources that result in a sudden change in the water pressure in general. References 1. T.Yamamoto,1982.Gravity waves and acoustic waves generated by submarine earthquakes, Soil Dyn. Earthquake Eng., 1, 75-82. 2. M. Stiassnie, 2010. Tsunamis and acoustic-gravity waves from underwater earthquakes, J. Eng. Math., 67, 23-32, doi:10.1007/s10665-009-9323-x. 3. U. Kadri and M. Staissnie, 2012. Acoustic-gravity waves interacting with the shelf break. J. Geophys. Res., 117, C03035, doi: 10.1029/2011JC007674. 4. E. Eyov, A. Klar, U. Kadri and M. Stiassnie, 2013. Progressive waves in a compressible ocean with elastic bottom, Wave Motion 50, 929-939. doi: 10.1016/j.wavemoti.2013.03.003 5. G. Hendin and M. Stiassnie, 2013. Tsunami and acoustic-gravity waves in water of constant depth, Phys. Fluids 25, 086103, doi: 10.1063/1.481799. 6. U. Kadri, 2016. Acoustic-gravity waves from an oscillating ice-block in arctic zones. Advances in Acoustics and Vibration, 8076108, http://dx.doi.org/10.1155/2016/8076108 7. T.C.A. Oliveira, U. Kadri, 2016. Acoustic-gravity waves from the 2004 Indian Ocean earthquake and tsunami. Journal of Geophysical Research: Oceans. doi: 10.1002/2016JC011742

  13. Facial neuroma masquerading as acoustic neuroma.

    Science.gov (United States)

    Sayegh, Eli T; Kaur, Gurvinder; Ivan, Michael E; Bloch, Orin; Cheung, Steven W; Parsa, Andrew T

    2014-10-01

    Facial nerve neuromas are rare benign tumors that may be initially misdiagnosed as acoustic neuromas when situated near the auditory apparatus. We describe a patient with a large cystic tumor with associated trigeminal, facial, audiovestibular, and brainstem dysfunction, which was suspicious for acoustic neuroma on preoperative neuroimaging. Intraoperative investigation revealed a facial nerve neuroma located in the cerebellopontine angle and internal acoustic canal. Gross total resection of the tumor via retrosigmoid craniotomy was curative. Transection of the facial nerve necessitated facial reanimation 4 months later via hypoglossal-facial cross-anastomosis. Clinicians should recognize the natural history, diagnostic approach, and management of this unusual and mimetic lesion. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Locating single-point sources from arrival times containing large picking errors (LPEs): the virtual field optimization method (VFOM)

    Science.gov (United States)

    Li, Xi-Bing; Wang, Ze-Wei; Dong, Long-Jun

    2016-01-01

    Microseismic monitoring systems using local location techniques tend to be timely, automatic and stable. One basic requirement of these systems is the automatic picking of arrival times. However, arrival times generated by automated techniques always contain large picking errors (LPEs), which may make the location solution unreliable and cause the integrated system to be unstable. To overcome the LPE issue, we propose the virtual field optimization method (VFOM) for locating single-point sources. In contrast to existing approaches, the VFOM optimizes a continuous and virtually established objective function to search the space for the common intersection of the hyperboloids, which is determined by sensor pairs other than the least residual between the model-calculated and measured arrivals. The results of numerical examples and in-site blasts show that the VFOM can obtain more precise and stable solutions than traditional methods when the input data contain LPEs. Furthermore, we discuss the impact of LPEs on objective functions to determine the LPE-tolerant mechanism, velocity sensitivity and stopping criteria of the VFOM. The proposed method is also capable of locating acoustic sources using passive techniques such as passive sonar detection and acoustic emission.

  15. Passive Mode Carbon Nanotube Underwater Acoustic Transducer

    Science.gov (United States)

    2016-09-20

    Acoustical transducer arrays can reflect a sound signal in reverse to the sender which can be used for echo location devices. [0008] In Jiang...States Patent No. 8,494,187) a sound wave generator is disclosed which includes a carbon nanotube structure and an insulating reinforcement structure... acoustic device that includes an electrode layer and a sound wave generator. The sound wave generator is disposed on a surface of the electrode

  16. Comparisons of auditorium acoustics measurements as a function of location in halls (A)

    DEFF Research Database (Denmark)

    Bradley, J. S.; Gade, Anders Christian; Siebein, G W

    1993-01-01

    In a measurement tour of nine U.S. concert halls measurements were made at 30 or more combinations of source and receiver position in each hall. Each of the three measurement teams (the University of Florida, the Danish Technical University, and the National Research Council of Canada) made paral....... The measurement results were also used to examine the influence of different measurement equipment and measurement procedures on the within hall variations of the various acoustical quantities. [Work partially supported by the Concert Hall Research Group.]...... parallel measurements of a number of modern room acoustics quantities using different equipment and measurement procedures. These results are compared on a seat-by-seat basis and the differences are explained in terms of earlier systematic studies of the effects of measurement procedure details...

  17. Acoustic cloaking and transformation acoustics

    International Nuclear Information System (INIS)

    Chen Huanyang; Chan, C T

    2010-01-01

    In this review, we give a brief introduction to the application of the new technique of transformation acoustics, which draws on a correspondence between coordinate transformation and material properties. The technique is formulated for both acoustic waves and linear liquid surface waves. Some interesting conceptual devices can be designed for manipulating acoustic waves. For example, we can design acoustic cloaks that make an object invisible to acoustic waves, and the cloak can either encompass or lie outside the object to be concealed. Transformation acoustics, as an analog of transformation optics, can go beyond invisibility cloaking. As an illustration for manipulating linear liquid surface waves, we show that a liquid wave rotator can be designed and fabricated to rotate the wave front. The acoustic transformation media require acoustic materials which are anisotropic and inhomogeneous. Such materials are difficult to find in nature. However, composite materials with embedded sub-wavelength resonators can in principle be made and such 'acoustic metamaterials' can exhibit nearly arbitrary values of effective density and modulus tensors to satisfy the demanding material requirements in transformation acoustics. We introduce resonant sonic materials and Helmholtz resonators as examples of acoustic metamaterials that exhibit resonant behaviour in effective density and effective modulus. (topical review)

  18. Computer based ultrasonic system for mechanical and acoustical characterization of materials

    International Nuclear Information System (INIS)

    Rosly Jaafar; Mohd Rozni Mohd Yusof; Khaidzir Hamzah; Md Supar Rohani; Rashdi Shah Ahmad; Amiruddin Shaari

    2001-01-01

    Propagation of both modes of ultrasonic waves velocity i.e. longitudinal (compressional) and transverse (shear), propagating in a material are closely linked with the material's physical and mechanical properties. By measuring both velocity modes, materials' properties such as Young's, bulk and shear moduli, compressibility, Poisson ratio and acoustic impedance can be determined. This paper describes the development of a system that is able to perform the above tasks and is known as Computer Based Ultrasonic for Mechanical and Acoustical Characterisation of Materials (UMC). The system was developed in the NDT Instrumentation and Signal Processing (NDTSP) laboratory of the Physics Department, Universiti Teknologi Malaysia. Measurements were made on four solid samples, namely, glass, copper, mild steel and aluminium. The results of measurements obtained were found to be in good agreement with the values of measurements made using standard methods. The main advantage of using this system over other methods is that single measurement of two ultrasonic velocity modes yields six material's properties. (Author)

  19. Automatic acoustic and vibration monitoring system for nuclear power plants

    International Nuclear Information System (INIS)

    Tothmatyas, Istvan; Illenyi, Andras; Kiss, Jozsef; Komaromi, Tibor; Nagy, Istvan; Olchvary, Geza

    1990-01-01

    A diagnostic system for nuclear power plant monitoring is described. Acoustic and vibration diagnostics can be applied to monitor various reactor components and auxiliary equipment including primary circuit machinery, leak detection, integrity of reactor vessel, loose parts monitoring. A noise diagnostic system has been developed for the Paks Nuclear Power Plant, to supervise the vibration state of primary circuit machinery. An automatic data acquisition and processing system is described for digitalizing and analysing diagnostic signals. (R.P.) 3 figs

  20. Force Limiting Vibration Tests Evaluated from both Ground Acoustic Tests and FEM Simulations of a Flight Like Vehicle System Assembly

    Science.gov (United States)

    Smith, Andrew; LaVerde, Bruce; Waldon, James; Hunt, Ron

    2014-01-01

    Marshall Space Flight Center has conducted a series of ground acoustic tests with the dual goals of informing analytical judgment, and validating analytical methods when estimating vibroacoustic responses of launch vehicle subsystems. The process of repeatedly correlating finite element-simulated responses with test-measured responses has assisted in the development of best practices for modeling and post-processing. In recent work, force transducers were integrated to measure interface forces at the base of avionics box equipment. Other force data was indirectly measured using strain gauges. The combination of these direct and indirect force measurements has been used to support and illustrate the advantages of implementing the Force Limiting approach for equipment qualification tests. The comparison of force response from integrated system level tests to measurements at the same locations during component level vibration tests provides an excellent illustration. A second comparison of the measured response cases from the system level acoustic tests to finite element simulations has also produced some principles for assessing the suitability of Finite Element Models (FEMs) for making vibroacoustics estimates. The results indicate that when FEM models are employed to guide force limiting choices, they should include sufficient detail to represent the apparent mass of the system in the frequency range of interest.

  1. Generation of thermo-acoustic waves from pulsed solar/IR radiation

    Science.gov (United States)

    Rahman, Aowabin

    Acoustic waves could potentially be used in a wide range of engineering applications; however, the high energy consumption in generating acoustic waves from electrical energy and the cost associated with the process limit the use of acoustic waves in industrial processes. Acoustic waves converted from solar radiation provide a feasible way of obtaining acoustic energy, without relying on conventional nonrenewable energy sources. One of the goals of this thesis project was to experimentally study the conversion of thermal to acoustic energy using pulsed radiation. The experiments were categorized into "indoor" and "outdoor" experiments, each with a separate experimental setup. The indoor experiments used an IR heater to power the thermo-acoustic lasers and were primarily aimed at studying the effect of various experimental parameters on the amplitude of sound waves in the low frequency range (below 130 Hz). The IR radiation was modulated externally using a chopper wheel and then impinged on a porous solid, which was housed inside a thermo-acoustic (TA) converter. A microphone located at a certain distance from the porous solid inside the TA converter detected the acoustic signals. The "outdoor" experiments, which were targeted at TA conversion at comparatively higher frequencies (in 200 Hz-3 kHz range) used solar energy to power the thermo-acoustic laser. The amplitudes (in RMS) of thermo-acoustic signals obtained in experiments using IR heater as radiation source were in the 80-100 dB range. The frequency of acoustic waves corresponded to the frequency of interceptions of the radiation beam by the chopper. The amplitudes of acoustic waves were influenced by several factors, including the chopping frequency, magnitude of radiation flux, type of porous material, length of porous material, external heating of the TA converter housing, location of microphone within the air column, and design of the TA converter. The time-dependent profile of the thermo-acoustic signals

  2. Evaluation of SHM system produced by additive manufacturing via acoustic emission and other NDT methods.

    Science.gov (United States)

    Strantza, Maria; Aggelis, Dimitrios G; de Baere, Dieter; Guillaume, Patrick; van Hemelrijck, Danny

    2015-10-21

    During the last decades, structural health monitoring (SHM) systems are used in order to detect damage in structures. We have developed a novel structural health monitoring approach, the so-called "effective structural health monitoring" (eSHM) system. The current SHM system is incorporated into a metallic structure by means of additive manufacturing (AM) and has the possibility to advance life safety and reduce direct operative costs. It operates based on a network of capillaries that are integrated into an AM structure. The internal pressure of the capillaries is continuously monitored by a pressure sensor. When a crack nucleates and reaches the capillary, the internal pressure changes signifying the existence of the flaw. The main objective of this paper is to evaluate the crack detection capacity of the eSHM system and crack location accuracy by means of various non-destructive testing (NDT) techniques. During this study, detailed acoustic emission (AE) analysis was applied in AM materials for the first time in order to investigate if phenomena like the Kaiser effect and waveform parameters used in conventional metals can offer valuable insight into the damage accumulation of the AM structure as well. Liquid penetrant inspection, eddy current and radiography were also used in order to confirm the fatigue damage and indicate the damage location on un-notched four-point bending AM metallic specimens with an integrated eSHM system. It is shown that the eSHM system in combination with NDT can provide correct information on the damage condition of additive manufactured metals.

  3. Operational monitoring of acoustic sensor networks

    Directory of Open Access Journals (Sweden)

    Boltenkov V.A.

    2015-06-01

    Full Text Available Acoustic sensor networks (ASN are widely used to monitor water leaks in the power generating systems. Since the ASN are used in harsh climatic conditions the failures of microphone elements of ASN are inevitable. That's why the failure detection of ASN elements is a problem of current interest. Two techniques of operational monitoring ASN are developed. Both of them are based on the placement of the test sound source within a network. The signal processing for ASN sensors had to detect the failed element. Techniques are based time difference of arrival (TDOA estimating at the each pair of ASN elements. TDOA estimates as argmaximum of cross-correlation function (CCF for signals on each microphone sensors pair. The M-sequence phase-shift keyed signal is applied as a test acoustic signal to ensure high accuracy of the CCF maximum estimation at low signal/noise ratio (SNR. The first technique is based on the isolation principle for TDOA sum at three points. It require to locate the test sound source in the far field. This is not always possible due to technological reasons. For the second proposed technique test sound source can be located near the ASN. It is based on a system of hyperbolic equations solving for each of the four elements of the ASN. Both techniques has been tested in the computer imitation experiment. It was found that for the SNR to –5 dB both techniques show unmistakable indicators of control quality. The second method requires significantly more time control.

  4. Laser-nucleated acoustic cavitation in focused ultrasound.

    Science.gov (United States)

    Gerold, Bjoern; Kotopoulis, Spiros; McDougall, Craig; McGloin, David; Postema, Michiel; Prentice, Paul

    2011-04-01

    Acoustic cavitation can occur in therapeutic applications of high-amplitude focused ultrasound. Studying acoustic cavitation has been challenging, because the onset of nucleation is unpredictable. We hypothesized that acoustic cavitation can be forced to occur at a specific location using a laser to nucleate a microcavity in a pre-established ultrasound field. In this paper we describe a scientific instrument that is dedicated to this outcome, combining a focused ultrasound transducer with a pulsed laser. We present high-speed photographic observations of laser-induced cavitation and laser-nucleated acoustic cavitation, at frame rates of 0.5×10(6) frames per second, from laser pulses of energy above and below the optical breakdown threshold, respectively. Acoustic recordings demonstrated inertial cavitation can be controllably introduced to the ultrasound focus. This technique will contribute to the understanding of cavitation evolution in focused ultrasound including for potential therapeutic applications. © 2011 American Institute of Physics

  5. Acoustic emission sensor radiation damage threshold experiment

    International Nuclear Information System (INIS)

    Beeson, K.M.; Pepper, C.E.

    1994-01-01

    Determination of the threshold for damage to acoustic emission sensors exposed to radiation is important in their application to leak detection in radioactive waste transport and storage. Proper response to system leaks is necessary to ensure the safe operation of these systems. A radiation impaired sensor could provide ''false negative or false positive'' indication of acoustic signals from leaks within the system. Research was carried out in the Radiochemical Technology Division at Oak Ridge National Laboratory to determine the beta/gamma radiation damage threshold for acoustic emission sensor systems. The individual system consisted of an acoustic sensor mounted with a two part epoxy onto a stainless steel waveguide. The systems were placed in an irradiation fixture and exposed to a Cobalt-60 source. After each irradiation, the sensors were recalibrated by Physical Acoustics Corporation. The results were compared to the initial calibrations performed prior to irradiation and a control group, not exposed to radiation, was used to validate the results. This experiment determines the radiation damage threshold of each acoustic sensor system and verifies its life expectancy, usefulness and reliability for many applications in radioactive environments

  6. Structural Dynamic Assessment of the GN2 Piping System for NASA's New and Powerful Reverberant Acoustic Test Facility

    Science.gov (United States)

    McNelis, Mark E.; Staab, Lucas D.; Akers, James C.; Hughes, WIlliam O.; Chang, Li, C.; Hozman, Aron D.; Henry, Michael W.

    2012-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has led the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA from 2007-2011. SAIC-Benham has completed construction of a new reverberant acoustic test facility to support the future testing needs of NASA's space exploration program and commercial customers. The large Reverberant Acoustic Test Facility (RATF) is approximately 101,000 cu ft in volume and was designed to operate at a maximum empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world's known active reverberant acoustic test facilities. Initial checkout acoustic testing was performed on March 2011 by SAIC-Benham at test levels up to 161 dB OASPL. During testing, several branches of the gaseous nitrogen (GN2) piping system, which supply the fluid to the noise generating acoustic modulators, failed at their "t-junctions" connecting the 12 inch supply line to their respective 4 inch branch lines. The problem was initially detected when the oxygen sensors in the horn room indicated a lower than expected oxygen level from which was inferred GN2 leaks in the piping system. In subsequent follow up inspections, cracks were identified in the failed "t-junction" connections through non-destructive evaluation testing . Through structural dynamic modeling of the piping system, the root cause of the "t-junction" connection failures was determined. The structural dynamic assessment identified several possible corrective design improvements to the horn room piping system. The effectiveness of the chosen design repairs were subsequently evaluated in September 2011 during acoustic verification testing to 161 dB OASPL.

  7. Energy based source location by using acoustic emission for damage detection in steel and composite CNG tank

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Il Sik; Han, Byeong Hee; Park, Choon Su; Yoon, Dong Jin [Center for Safety Measurements, Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2015-10-15

    Acoustic emission (AE) is an effective nondestructive test that uses transient elastic wave generated by the rapid release of energy within a material to detect any further growth or expansion of existing defects. Over the past decades, because of environmental issues, the use of compressed natural gas (CNG) as an alternative fuel for vehicles is increasing because of environmental issues. For this reason, the importance and necessity of detecting defects on a CNG fuel tank has also come to the fore. The conventional AE method used for source location is highly affected by the wave speed on the structure, and this creates problems in inspecting a composite CNG fuel tank. Because the speed and dispersion characteristics of the wave are different according to direction of structure and laminated layers. In this study, both the conventional AE method and the energy based contour map method were used for source location. This new method based on pre-acquired D/B was used for overcoming the limitation of damage localization in a composite CNG fuel tank specimen which consists of a steel liner cylinder overwrapped by GFRP. From the experimental results, it is observed that the damage localization is determined with a small error at all tested points by using the energy based contour map method, while there were a number of mis-locations or large errors at many tested points by using the conventional AE method. Therefore, the energy based contour map method used in this work is more suitable technology for inspecting composite structures.

  8. Imaging of heart acoustic based on the sub-space methods using a microphone array.

    Science.gov (United States)

    Moghaddasi, Hanie; Almasganj, Farshad; Zoroufian, Arezoo

    2017-07-01

    Heart disease is one of the leading causes of death around the world. Phonocardiogram (PCG) is an important bio-signal which represents the acoustic activity of heart, typically without any spatiotemporal information of the involved acoustic sources. The aim of this study is to analyze the PCG by employing a microphone array by which the heart internal sound sources could be localized, too. In this paper, it is intended to propose a modality by which the locations of the active sources in the heart could also be investigated, during a cardiac cycle. In this way, a microphone array with six microphones is employed as the recording set up to be put on the human chest. In the following, the Group Delay MUSIC algorithm which is a sub-space based localization method is used to estimate the location of the heart sources in different phases of the PCG. We achieved to 0.14cm mean error for the sources of first heart sound (S 1 ) simulator and 0.21cm mean error for the sources of second heart sound (S 2 ) simulator with Group Delay MUSIC algorithm. The acoustical diagrams created for human subjects show distinct patterns in various phases of the cardiac cycles such as the first and second heart sounds. Moreover, the evaluated source locations for the heart valves are matched with the ones that are obtained via the 4-dimensional (4D) echocardiography applied, to a real human case. Imaging of heart acoustic map presents a new outlook to indicate the acoustic properties of cardiovascular system and disorders of valves and thereby, in the future, could be used as a new diagnostic tool. Copyright © 2017. Published by Elsevier B.V.

  9. Flaw identification using acoustic emission

    International Nuclear Information System (INIS)

    Woodward, B.; McDonald, N.R.

    1975-01-01

    Acoustic emission 'signatures' contain information about the fine structure of metallurgical source events and their interpretation may provide a means of assessing the severity of internal flaws as well as surface flaws. The ultimate aim of this research on signature analysis is to develop a real time non-destructive testing technique having the capability of flaw recognition as well as flaw location in nuclear reactor components and structures under stress. Thus the requisite, unlike that in most acoustic emission work to date, is for a technique which affords discrimination between acoustic emission from different types of flaws propagating simultaneously. The approach described here requires detailed analysis of the emission signatures in terms of a specific statistical parameter, energy spectral density. In order to realise the full inspection potential of acoustic emission monitoring data obtained from zirconium and steel testpieces have been correlated with metallurgical condition and mechanical behaviour, since the nature of emission signatures is strongly affected by the physical characteristics and internal structure of the material. (Auth.)

  10. Distributed acoustic sensing technique and its field trial in SAGD well

    Science.gov (United States)

    Han, Li; He, Xiangge; Pan, Yong; Liu, Fei; Yi, Duo; Hu, Chengjun; Zhang, Min; Gu, Lijuan

    2017-10-01

    Steam assisted gravity drainage (SAGD) is a very promising way for the development of heavy oil, extra heavy oil and tight oil reservoirs. Proper monitoring of the SAGD operations is essential to avoid operational issues and improve efficiency. Among all the monitoring techniques, micro-seismic monitoring and related interpretation method can give useful information about the steam chamber development and has been extensively studied. Distributed acoustic sensor (DAS) based on Rayleigh backscattering is a newly developed technique that can measure acoustic signal at all points along the sensing fiber. In this paper, we demonstrate a DAS system based on dual-pulse heterodyne demodulation technique and did field trial in SAGD well located in Xinjiang Oilfield, China. The field trail results validated the performance of the DAS system and indicated its applicability in steam-chamber monitoring and hydraulic monitoring.

  11. Locating the Tohoku-Oki 2011 tsunami source using acoustic-gravity waves

    OpenAIRE

    Andriamiranto Raveloson; Rainer Kind; Xiaohui Yuan; L. Cerana

    2012-01-01

    The giant Tohoku-Oki earthquake of 11 March 2011 in offshore Japan did not only generate tsunami waves in the ocean but also infrasound (or acoustic-gravity) waves in the atmosphere. We indentified ultra-long-period signals (>500s) in the recordings of infrasound stations in northeast Asia, the northwest Pacific, and Alaska. Their source was fond close to the earthquake epicenter. Therefore, we conclude that in general, infrasound observations after a large offshore earthquake are evidence th...

  12. Measurement of acoustic glitches in solar-type stars from oscillation frequencies observed by Kepler

    Energy Technology Data Exchange (ETDEWEB)

    Mazumdar, A. [Homi Bhabha Centre for Science Education, TIFR, V. N. Purav Marg, Mankhurd, Mumbai 400088 (India); Monteiro, M. J. P. F. G.; Cunha, M. S. [Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Ballot, J. [CNRS, Institut de Recherche en Astrophysique et Planétologie, 14 avenue Edouard Belin, F-31400 Toulouse (France); Antia, H. M. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Basu, S. [Astronomy Department, Yale University, P.O. Box 208101, New Haven, CT 065208101 (United States); Houdek, G.; Silva Aguirre, V.; Christensen-Dalsgaard, J.; Metcalfe, T. S. [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Mathur, S. [High Altitude Observatory, NCAR, P.O. Box 3000, Boulder, CO 80307 (United States); García, R. A. [Laboratoire AIM, CEA/DSM, CNRS, Université Paris Diderot, IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Salabert, D. [Laboratoire Lagrange, UMR7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d' Azur, F-06304 Nice (France); Verner, G. A.; Chaplin, W. J. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Sanderfer, D. T. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Seader, S. E.; Smith, J. C. [SETI Institute/NASA Ames Research Center, Moffett Field, CA 94035 (United States)

    2014-02-10

    For the very best and brightest asteroseismic solar-type targets observed by Kepler, the frequency precision is sufficient to determine the acoustic depths of the surface convective layer and the helium ionization zone. Such sharp features inside the acoustic cavity of the star, which we call acoustic glitches, create small oscillatory deviations from the uniform spacing of frequencies in a sequence of oscillation modes with the same spherical harmonic degree. We use these oscillatory signals to determine the acoustic locations of such features in 19 solar-type stars observed by the Kepler mission. Four independent groups of researchers utilized the oscillation frequencies themselves, the second differences of the frequencies and the ratio of the small and large separation to locate the base of the convection zone and the second helium ionization zone. Despite the significantly different methods of analysis, good agreement was found between the results of these four groups, barring a few cases. These results also agree reasonably well with the locations of these layers in representative models of the stars. These results firmly establish the presence of the oscillatory signals in the asteroseismic data and the viability of several techniques to determine the location of acoustic glitches inside stars.

  13. Integration of acoustic and light sensors for marine bio-mining

    Science.gov (United States)

    Wiegand, Gordon

    2016-05-01

    Maximum diversity of life exists within the estuaries and coral reefs of the Globe. The absence of vertebrate and other land dwelling adaptations has resulted in an enormous range of complexity among invertebrates and their symbiotic biome resulting in the generation of compounds finding uses in anti-tumor and antibiotic applications. It has been widely reported that the greatest factor limiting progress in characterizing and processing new therapeutics derived from invertebrates is the lack of adequate original material. Symbiotic bacteria within specific tunicates often synthesize antitumor compounds as secondary metabolites. We describe a 3-stage protocol that utilizes acoustic and photonic analysis of large areas of marine ecosystem and life forms. We refer to this as Estuary Assessment System (EAS), which includes a multi-frequency acoustic transducer/sensing instrument mounted on our research vessel. This generates a topological map of surveyed tracks of marine locations known to be habitats of useful actinobacteria laden invertebrates. Photonic devices are used to generate image and pulse data leading to location, identification and isolation of tunicates and actinobacteria.

  14. Acoustically induced transparency using Fano resonant periodic arrays

    KAUST Repository

    El-Amin, Mohamed

    2015-10-22

    A three-dimensional acoustic device, which supports Fano resonance and induced transparency in its response to an incident sound wave, is designed and fabricated. These effects are generated from the destructive interference of closely coupled one broad- and one narrow-band acoustic modes. The proposed design ensures excitation and interference of two spectrally close modes by locating a small pipe inside a wider and longer one. Indeed, numerical simulations and experiments demonstrate that this simple-to-fabricate structure can be used to generate Fano resonance as well as acoustically induced transparency with promising applications in sensing, cloaking, and imaging.

  15. Acoustically induced transparency using Fano resonant periodic arrays

    KAUST Repository

    El-Amin, Mohamed; Elayouch, A.; Farhat, Mohamed; Addouche, M.; Khelif, A.; Bagci, Hakan

    2015-01-01

    A three-dimensional acoustic device, which supports Fano resonance and induced transparency in its response to an incident sound wave, is designed and fabricated. These effects are generated from the destructive interference of closely coupled one broad- and one narrow-band acoustic modes. The proposed design ensures excitation and interference of two spectrally close modes by locating a small pipe inside a wider and longer one. Indeed, numerical simulations and experiments demonstrate that this simple-to-fabricate structure can be used to generate Fano resonance as well as acoustically induced transparency with promising applications in sensing, cloaking, and imaging.

  16. Acoustic Characterization of a Multi-Rotor Unmanned Aircraft

    Science.gov (United States)

    Feight, Jordan; Gaeta, Richard; Jacob, Jamey

    2017-11-01

    In this study, the noise produced by a small multi-rotor rotary wing aircraft, or drone, is measured and characterized. The aircraft is tested in different configurations and environments to investigate specific parameters and how they affect the acoustic signature of the system. The parameters include rotor RPM, the number of rotors, distance and angle of microphone array from the noise source, and the ambient environment. The testing environments include an anechoic chamber for an idealized setting and both indoor and outdoor settings to represent real world conditions. PIV measurements are conducted to link the downwash and vortical flow structures from the rotors with the noise generation. The significant factors that arise from this study are the operational state of the aircraft and the microphone location (or the directivity of the noise source). The directivity in the rotor plane was shown to be omni-directional, regardless of the varying parameters. The tonal noise dominates the low to mid frequencies while the broadband noise dominates the higher frequencies. The fundamental characteristics of the acoustic signature appear to be invariant to the number of rotors. Flight maneuvers of the aircraft also significantly impact the tonal content in the acoustic signature.

  17. Perceptual and Acoustic Reliability Estimates for the Speech Disorders Classification System (SDCS)

    Science.gov (United States)

    Shriberg, Lawrence D.; Fourakis, Marios; Hall, Sheryl D.; Karlsson, Heather B.; Lohmeier, Heather L.; McSweeny, Jane L.; Potter, Nancy L.; Scheer-Cohen, Alison R.; Strand, Edythe A.; Tilkens, Christie M.; Wilson, David L.

    2010-01-01

    A companion paper describes three extensions to a classification system for paediatric speech sound disorders termed the Speech Disorders Classification System (SDCS). The SDCS uses perceptual and acoustic data reduction methods to obtain information on a speaker's speech, prosody, and voice. The present paper provides reliability estimates for…

  18. Systems and methods for separating particles utilizing engineered acoustic contrast capture particles

    Science.gov (United States)

    Kaduchak, Gregory; Ward, Michael D.

    2018-03-06

    An apparatus for separating particles from a medium includes a capillary defining a flow path therein that is in fluid communication with a medium source. The medium source includes engineered acoustic contrast capture particle having a predetermined acoustic contrast. The apparatus includes a vibration generator that is operable to produce at least one acoustic field within the flow path. The acoustic field produces a force potential minima for positive acoustic contrast particles and a force potential minima for negative acoustic contrast particles in the flow path and drives the engineered acoustic contrast capture particles to either the force potential minima for positive acoustic contrast particles or the force potential minima for negative acoustic contrast particles.

  19. Automatic tuning of Bragg condition in a radio-acoustic system for PBL temperature profile measurement

    Energy Technology Data Exchange (ETDEWEB)

    Bonino, G; Trivero, P

    1985-01-01

    A Radio-Acoustic Sounding System (RASS) with acoustic wavelength lambda/sub a/ approx. 1m was designed and successfully tested. The system proved to be capable of measuring the vertical temperature profile in the Planetary Boundary Layer (PBL) with an accuracy and vertical resolution comparable to that of traditional apparatus (radiothermosondes borne by tethered or disposable balloons, thermosondes borne by aircraft and so on), yet combined with the advantages typical of remote sensing techniques. Up to the summer of 1983 the system needed attendance by an operator who had to identify the acoustic sounding frequency affording the fundamental condition of Bragg resonance between acoustic and radio wavelengths. Features and performance of the new completely automatic RASS arrangement are presented. These include the possibility of obtaining average thermal vertical profiles at preset time intervals. Maximum range of the possibility of obtaining average thermal vertical profiles at preset time intervals. Maximum range of measurements obtained in about 1000 1/2-h averages was: in 90% of cases greater than or equal to 600 m; in 50% of cases greater than or equal to 1100m. Such results indicate the usefulness of automatic RASS as a tool for meteorological purposes and for the application of air pollution control strategies.

  20. Vibro-acoustic Imaging at the Breazeale Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Smith, James Arthur [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jewell, James Keith [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lee, James Edwin [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-01

    The INL is developing Vibro-acoustic imaging technology to characterize microstructure in fuels and materials in spent fuel pools and within reactor vessels. A vibro-acoustic development laboratory has been established at the INL. The progress in developing the vibro-acoustic technology at the INL is the focus of this report. A successful technology demonstration was performed in a working TRIGA research reactor. Vibro-acoustic imaging was performed in the reactor pool of the Breazeale reactor in late September of 2015. A confocal transducer driven at a nominal 3 MHz was used to collect the 60 kHz differential beat frequency induced in a spent TRIGA fuel rod and empty gamma tube located in the main reactor water pool. Data was collected and analyzed with the INLDAS data acquisition software using a short time Fourier transform.

  1. In process acoustic emission in multirun submerged arc welding

    International Nuclear Information System (INIS)

    Asty, M.; Birac, C.

    1980-01-01

    In order to avoid the formation of deep grooves when repairing defects in welded joints in heavy plates, an investigation was made aiming to detect and locate the defects by in-process acoustic emission in multirun submerged arc welding. Twelve defects (lack of penetration, cracks, inclusions, lack of fusion together with inclusions, blowholes) were intentionally introduced when the first plate was welded. A space-time method for processing the acoustic activity during welding allowed the detection and the location of the intentional defects as well as of the most important accidental defects evidenced by ultrasonic testing [fr

  2. Acoustic Levitation With One Driver

    Science.gov (United States)

    Wang, T. G.; Rudnick, I.; Elleman, D. D.; Stoneburner, J. D.

    1985-01-01

    Report discusses acoustic levitation in rectangular chamber using one driver mounted at corner. Placement of driver at corner enables it to couple effectively to acoustic modes along all three axes. Use of single driver reduces cost, complexity and weight of levitation system below those of three driver system.

  3. Towards Informative Path Planning for Acoustic SLAM

    OpenAIRE

    Evers, C; Moore, A; Naylor, P

    2016-01-01

    Acoustic scene mapping is a challenging task as microphone arrays can often localize sound sources only in terms of their directions. Spatial diversity can be exploited constructively to infer source-sensor range when using microphone arrays installed on moving platforms, such as robots. As the absolute location of a moving robot is often unknown in practice, Acoustic Simultaneous Localization And Mapping (a-SLAM) is required in order to localize the moving robot?s positions and jointly map t...

  4. Acoustical Imaging

    CERN Document Server

    Akiyama, Iwaki

    2009-01-01

    The 29th International Symposium on Acoustical Imaging was held in Shonan Village, Kanagawa, Japan, April 15-18, 2007. This interdisciplinary Symposium has been taking place every two years since 1968 and forms a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. In the course of the years the volumes in the Acoustical Imaging Series have developed and become well-known and appreciated reference works. Offering both a broad perspective on the state-of-the-art in the field as well as an in-depth look at its leading edge research, this Volume 29 in the Series contains again an excellent collection of seventy papers presented in nine major categories: Strain Imaging Biological and Medical Applications Acoustic Microscopy Non-Destructive Evaluation and Industrial Applications Components and Systems Geophysics and Underwater Imaging Physics and Mathematics Medical Image Analysis FDTD method and Other Numerical Simulations Audience Researcher...

  5. A training system of orientation and mobility for blind people using acoustic virtual reality.

    Science.gov (United States)

    Seki, Yoshikazu; Sato, Tetsuji

    2011-02-01

    A new auditory orientation training system was developed for blind people using acoustic virtual reality (VR) based on a head-related transfer function (HRTF) simulation. The present training system can reproduce a virtual training environment for orientation and mobility (O&M) instruction, and the trainee can walk through the virtual training environment safely by listening to sounds such as vehicles, stores, ambient noise, etc., three-dimensionally through headphones. The system can reproduce not only sound sources but also sound reflection and insulation, so that the trainee can learn both sound location and obstacle perception skills. The virtual training environment is described in extensible markup language (XML), and the O&M instructor can edit it easily according to the training curriculum. Evaluation experiments were conducted to test the efficiency of some features of the system. Thirty subjects who had not acquired O&M skills attended the experiments. The subjects were separated into three groups: a no-training group, a virtual-training group using the present system, and a real-training group in real environments. The results suggested that virtual-training can reduce "veering" more than real-training and also can reduce stress as much as real training. The subjective technical and anxiety scores also improved.

  6. Detection of Volatile Organics Using a Surface Acoustic Wave Array System

    International Nuclear Information System (INIS)

    ANDERSON, LAWRENCE F.; BARTHOLOMEW, JOHN W.; CERNOSEK, RICHARD W.; COLBURN, CHRISTOPHER W.; CROOKS, R.M.; MARTINEZ, R.F.; OSBOURN, GORDON C.; RICCO, A.J.; STATON, ALAN W.; YELTON, WILLIAM G.

    1999-01-01

    A chemical sensing system based on arrays of surface acoustic wave (SAW) delay lines has been developed for identification and quantification of volatile organic compounds (VOCs). The individual SAW chemical sensors consist of interdigital transducers patterned on the surface of an ST-cut quartz substrate to launch and detect the acoustic waves and a thin film coating in the SAW propagation path to perturb the acoustic wave velocity and attenuation during analyte sorption. A diverse set of material coatings gives the sensor arrays a degree of chemical sensitivity and selectivity. Materials examined for sensor application include the alkanethiol-based self-assembled monolayer, plasma-processed films, custom-synthesized conventional polymers, dendrimeric polymers, molecular recognition materials, electroplated metal thin films, and porous metal oxides. All of these materials target a specific chemical fi.mctionality and the enhancement of accessible film surface area. Since no one coating provides absolute analyte specificity, the array responses are further analyzed using a visual-empirical region-of-influence (VERI) pattern recognition algorithm. The chemical sensing system consists of a seven-element SAW array with accompanying drive and control electronics, sensor signal acquisition electronics, environmental vapor sampling hardware, and a notebook computer. Based on data gathered for individual sensor responses, greater than 93%-accurate identification can be achieved for any single analyte from a group of 17 VOCs and water

  7. Detection of Volatile Organics Using a Surface Acoustic Wave Array System

    Energy Technology Data Exchange (ETDEWEB)

    ANDERSON, LAWRENCE F.; BARTHOLOMEW, JOHN W.; CERNOSEK, RICHARD W.; COLBURN, CHRISTOPHER W.; CROOKS, R.M.; MARTINEZ, R.F.; OSBOURN, GORDON C.; RICCO, A.J.; STATON, ALAN W.; YELTON, WILLIAM G.

    1999-10-14

    A chemical sensing system based on arrays of surface acoustic wave (SAW) delay lines has been developed for identification and quantification of volatile organic compounds (VOCs). The individual SAW chemical sensors consist of interdigital transducers patterned on the surface of an ST-cut quartz substrate to launch and detect the acoustic waves and a thin film coating in the SAW propagation path to perturb the acoustic wave velocity and attenuation during analyte sorption. A diverse set of material coatings gives the sensor arrays a degree of chemical sensitivity and selectivity. Materials examined for sensor application include the alkanethiol-based self-assembled monolayer, plasma-processed films, custom-synthesized conventional polymers, dendrimeric polymers, molecular recognition materials, electroplated metal thin films, and porous metal oxides. All of these materials target a specific chemical fi.mctionality and the enhancement of accessible film surface area. Since no one coating provides absolute analyte specificity, the array responses are further analyzed using a visual-empirical region-of-influence (VERI) pattern recognition algorithm. The chemical sensing system consists of a seven-element SAW array with accompanying drive and control electronics, sensor signal acquisition electronics, environmental vapor sampling hardware, and a notebook computer. Based on data gathered for individual sensor responses, greater than 93%-accurate identification can be achieved for any single analyte from a group of 17 VOCs and water.

  8. Location estimation method of steam leak in pipeline using leakage area analysis

    International Nuclear Information System (INIS)

    Kim, Se Oh; Jeon, Hyeong Seop; Son, Ki Sung; Park, Jong Won

    2016-01-01

    It is important to have a pipeline leak-detection system that determines the presence of a leak and quickly identifies its location. Current leak detection methods use a acoustic emission sensors, microphone arrays, and camera images. Recently, many researchers have been focusing on using cameras for detecting leaks. The advantage of this method is that it can survey a wide area and monitor a pipeline over a long distance. However, conventional methods using camera monitoring are unable to target an exact leak location. In this paper, we propose a method of detecting leak locations using leak-detection results combined with multi-frame analysis. The proposed method is verified by experiment

  9. Location estimation method of steam leak in pipeline using leakage area analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Se Oh; Jeon, Hyeong Seop; Son, Ki Sung [Sae An Engineering Corp., Seoul (Korea, Republic of); Park, Jong Won [Dept. of Information Communications Engineering, Chungnam National University, Daejeon (Korea, Republic of)

    2016-10-15

    It is important to have a pipeline leak-detection system that determines the presence of a leak and quickly identifies its location. Current leak detection methods use a acoustic emission sensors, microphone arrays, and camera images. Recently, many researchers have been focusing on using cameras for detecting leaks. The advantage of this method is that it can survey a wide area and monitor a pipeline over a long distance. However, conventional methods using camera monitoring are unable to target an exact leak location. In this paper, we propose a method of detecting leak locations using leak-detection results combined with multi-frame analysis. The proposed method is verified by experiment.

  10. Nondestructive online testing method for friction stir welding using acoustic emission

    Science.gov (United States)

    Levikhina, Anastasiya

    2017-12-01

    The paper reviews the possibility of applying the method of acoustic emission for online monitoring of the friction stir welding process. It is shown that acoustic emission allows the detection of weld defects and their location in real time. The energy of an acoustic signal and the median frequency are suggested to be used as informative parameters. The method of calculating the median frequency with the use of a short time Fourier transform is applied for the identification of correlations between the defective weld structure and properties of the acoustic emission signals received during welding.

  11. A Survey of Sound Source Localization Methods in Wireless Acoustic Sensor Networks

    Directory of Open Access Journals (Sweden)

    Maximo Cobos

    2017-01-01

    Full Text Available Wireless acoustic sensor networks (WASNs are formed by a distributed group of acoustic-sensing devices featuring audio playing and recording capabilities. Current mobile computing platforms offer great possibilities for the design of audio-related applications involving acoustic-sensing nodes. In this context, acoustic source localization is one of the application domains that have attracted the most attention of the research community along the last decades. In general terms, the localization of acoustic sources can be achieved by studying energy and temporal and/or directional features from the incoming sound at different microphones and using a suitable model that relates those features with the spatial location of the source (or sources of interest. This paper reviews common approaches for source localization in WASNs that are focused on different types of acoustic features, namely, the energy of the incoming signals, their time of arrival (TOA or time difference of arrival (TDOA, the direction of arrival (DOA, and the steered response power (SRP resulting from combining multiple microphone signals. Additionally, we discuss methods not only aimed at localizing acoustic sources but also designed to locate the nodes themselves in the network. Finally, we discuss current challenges and frontiers in this field.

  12. Photo-acoustic and video-acoustic methods for sensing distant sound sources

    Science.gov (United States)

    Slater, Dan; Kozacik, Stephen; Kelmelis, Eric

    2017-05-01

    Long range telescopic video imagery of distant terrestrial scenes, aircraft, rockets and other aerospace vehicles can be a powerful observational tool. But what about the associated acoustic activity? A new technology, Remote Acoustic Sensing (RAS), may provide a method to remotely listen to the acoustic activity near these distant objects. Local acoustic activity sometimes weakly modulates the ambient illumination in a way that can be remotely sensed. RAS is a new type of microphone that separates an acoustic transducer into two spatially separated components: 1) a naturally formed in situ acousto-optic modulator (AOM) located within the distant scene and 2) a remote sensing readout device that recovers the distant audio. These two elements are passively coupled over long distances at the speed of light by naturally occurring ambient light energy or other electromagnetic fields. Stereophonic, multichannel and acoustic beam forming are all possible using RAS techniques and when combined with high-definition video imagery it can help to provide a more cinema like immersive viewing experience. A practical implementation of a remote acousto-optic readout device can be a challenging engineering problem. The acoustic influence on the optical signal is generally weak and often with a strong bias term. The optical signal is further degraded by atmospheric seeing turbulence. In this paper, we consider two fundamentally different optical readout approaches: 1) a low pixel count photodiode based RAS photoreceiver and 2) audio extraction directly from a video stream. Most of our RAS experiments to date have used the first method for reasons of performance and simplicity. But there are potential advantages to extracting audio directly from a video stream. These advantages include the straight forward ability to work with multiple AOMs (useful for acoustic beam forming), simpler optical configurations, and a potential ability to use certain preexisting video recordings. However

  13. Monitoring of diesel engine combustions based on the acoustic source characterisation of the exhaust system

    Science.gov (United States)

    Jiang, J.; Gu, F.; Gennish, R.; Moore, D. J.; Harris, G.; Ball, A. D.

    2008-08-01

    Acoustic methods are among the most useful techniques for monitoring the condition of machines. However, the influence of background noise is a major issue in implementing this method. This paper introduces an effective monitoring approach to diesel engine combustion based on acoustic one-port source theory and exhaust acoustic measurements. It has been found that the strength, in terms of pressure, of the engine acoustic source is able to provide a more accurate representation of the engine combustion because it is obtained by minimising the reflection effects in the exhaust system. A multi-load acoustic method was then developed to determine the pressure signal when a four-cylinder diesel engine was tested with faults in the fuel injector and exhaust valve. From the experimental results, it is shown that a two-load acoustic method is sufficient to permit the detection and diagnosis of abnormalities in the pressure signal, caused by the faults. This then provides a novel and yet reliable method to achieve condition monitoring of diesel engines even if they operate in high noise environments such as standby power stations and vessel chambers.

  14. Active structural acoustic control of noise transmission through double panel systems

    Science.gov (United States)

    Carneal, James P.; Fuller, Chris R.

    1995-04-01

    A preliminary parametric study of active control of sound transmission through double panel systems has been experimentally performed. The technique used is the active structural acoustic control (ASAC) approach where control inputs, in the form of piezoelectric actuators, were applied to the structure while the radiated pressure field was minimized. Results indicate the application of control inputs to the radiating panel resulted in greater transmission loss due to its direct effect on the nature of the structural-acoustic coupling between the radiating panel and the receiving chamber. Increased control performance was seen in a double panel system consisting of a stiffer radiating panel with a lower modal density. As expected, more effective control of a radiating panel excited on-resonance is achieved over one excited off-resonance. In general, the results validate the ASAC approach for double panel systems and demonstrate that it is possible to take advantage of double panel behavior to enhance control performance, although it is clear that further research must be done to understand the physics involved.

  15. Location of leaks in pressurized underground pipelines

    International Nuclear Information System (INIS)

    Eckert, E.G.; Maresca, J.W. Jr.

    1993-01-01

    Millions of underground storage tanks (UST) are used to store petroleum and other chemicals. The pressurized underground pipelines associated with USTs containing petroleum motor fuels are typically 2 in. in diameter and 50 to 200 ft in length. These pipelines typically operate at pressures of 20 to 30 psi. Longer lines, with diameters up to 4 in., are found in some high-volume facilities. There are many systems that can be used to detect leaks in pressurized underground pipelines. When a leak is detected, the first step in the remediation process is to find its location. Passive-acoustic measurements, combined with advanced signal-processing techniques, provide a nondestructive method of leak location that is accurate and relatively simple, and that can be applied to a wide variety of pipelines and pipeline products

  16. Obtaining location/arrival-time and location/outflow-quantity distributions for steady flow systems

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    A steady, two-dimensional flow system is used to demonstrate the application of location/arrival-time and location/outflow-quantity curves in determining the environmental consequences of groundwater contamination. The subsurface geologic and hydrologic evaluations needed to obtain the arrival results involve a sequence of four phases: system identification, new potential determination, flow systems kinematics, and contaminant transport analysis. Once these phases are completed, they are effectively summarized and easily used to evaluate environmental consequences through the arrival distributions

  17. Acoustic observations of internal tides and tidal currents in shallow water.

    Science.gov (United States)

    Turgut, Altan; Mignerey, Peter C; Goldstein, David J; Schindall, Jeffrey A

    2013-04-01

    Significant acoustic travel-time variability and frequency shifts of acoustic intensity level curves in broadband signal spectrograms were measured in the East China Sea during the summer of 2008. The broadband pulses (270-330 Hz) were transmitted from a fixed source and received at a bottomed horizontal array, located at the 33 km range. The acoustic intensity level curves of the received signals indicate regular frequency shifts that are well correlated with the measured internal tides. Similarly, regular travel-time shifts of the acoustic mode arrivals correlate well with the barotropic tides and can be explained by tidal currents along the acoustic propagation track. These observations indicate the potential of monitoring internal tides and tidal currents using low-frequency acoustic signals propagating at long ranges.

  18. Acoustic Characterization and Prediction of Representative, Small-Scale Rotary-Wing Unmanned Aircraft System Components

    Science.gov (United States)

    Zawodny, Nikolas S.; Boyd, D. Douglas, Jr.; Burley, Casey L.

    2016-01-01

    In this study, hover performance and acoustic measurements are taken on two different isolated rotors representative of small-scale rotary-wing unmanned aircraft systems (UAS) for a range of rotation rates. Each rotor system consists of two fixed-pitch blades powered by a brushless motor. For nearly the same thrust condition, significant differences in overall sound pressure level (OASPL), up to 8 dB, and directivity were observed between the two rotor systems. Differences are shown to be in part attributed to different rotor tip speeds, along with increased broadband and motor noise levels. In addition to acoustic measurements, aeroacoustic predictions were implemented in order to better understand the noise content of the rotor systems. Numerical aerodynamic predictions were computed using the unsteady Reynoldsaveraged Navier Stokes code OVERFLOW2 on one of the isolated rotors, while analytical predictions were computed using the Propeller Analysis System of the Aircraft NOise Prediction Program (ANOPP-PAS) on the two rotor configurations. Preliminary semi-empirical frequency domain broadband noise predictions were also carried out based on airfoil self-noise theory in a rotational reference frame. The prediction techniques further supported trends identified in the experimental data analysis. The brushless motors were observed to be important noise contributors and warrant further investigation. It is believed that UAS acoustic prediction capabilities must consider both rotor and motor components as part of a combined noise-generating system.

  19. Multiscale modeling of acoustic shielding materials

    NARCIS (Netherlands)

    Gao, K.; Dommelen, van J.A.W.; Geers, M.G.D.

    2012-01-01

    It is very important to protect high-tech systems from acoustic excitation when operating in a noisy environment. Some passive absorbing materials such as acoustic foams can improve the performance which depends on the interaction of the acoustic wave and the microstructure of the foam.

  20. Acoustic Green's function extraction in the ocean

    Science.gov (United States)

    Zang, Xiaoqin

    The acoustic Green's function (GF) is the key to understanding the acoustic properties of ocean environments. With knowledge of the acoustic GF, the physics of sound propagation, such as dispersion, can be analyzed; underwater communication over thousands of miles can be understood; physical properties of the ocean, including ocean temperature, ocean current speed, as well as seafloor bathymetry, can be investigated. Experimental methods of acoustic GF extraction can be categorized as active methods and passive methods. Active methods are based on employment of man-made sound sources. These active methods require less computational complexity and time, but may cause harm to marine mammals. Passive methods cost much less and do not harm marine mammals, but require more theoretical and computational work. Both methods have advantages and disadvantages that should be carefully tailored to fit the need of each specific environment and application. In this dissertation, we study one passive method, the noise interferometry method, and one active method, the inverse filter processing method, to achieve acoustic GF extraction in the ocean. The passive method of noise interferometry makes use of ambient noise to extract an approximation to the acoustic GF. In an environment with a diffusive distribution of sound sources, sound waves that pass through two hydrophones at two locations carry the information of the acoustic GF between these two locations; by listening to the long-term ambient noise signals and cross-correlating the noise data recorded at two locations, the acoustic GF emerges from the noise cross-correlation function (NCF); a coherent stack of many realizations of NCFs yields a good approximation to the acoustic GF between these two locations, with all the deterministic structures clearly exhibited in the waveform. To test the performance of noise interferometry in different types of ocean environments, two field experiments were performed and ambient noise

  1. DESIGN OF A REAL TIME REMOTE VEHICLE LOCATION SYSTEM

    Directory of Open Access Journals (Sweden)

    Ahmet Emir DİRİK

    2004-02-01

    Full Text Available In this study, a low-cost, real-time vehicle location system is developed. The vehicle location system includes three main modules, i.e. positioning, wireless communication and digital map modules. The positioning module used in location systems computes position of the mobile vehicle. These vehicle location data are transmitted through a wireless communication system to host. The host has a capability to monitor a fleet of vehicles by analyzing data collected from wireless communication system. In this project, mobile vehicle location positions can be computed in a range of 10m position error and by using these position data, its possible to monitor the fleet of mobile vehicles on a digital map in the observation and control center. In this study, vehicle analog mobile radios are used to establish wireless communication system. Thus, there is no need to use satellite or GSM systems for communication and a low-cost and high-performance vehicle location system is realized.

  2. Method and apparatus for generating acoustic waves

    International Nuclear Information System (INIS)

    Rao, G.V.; Gopal, R.

    1982-01-01

    A portable source of acoustic waves comprises a sample of iron-nickel alloy including an austenite phase cooled to become martensite, and a wave guide to transmit the acoustic waves. The source is applied to the pressure boundary region of a pressurized water reactor to simulate an actual metal flaw and test the calibration of the monitoring and surveillance system. With at most 29.7% nickel in the sample, the source provides acoustic emission due to ductile deformation, and with at least 30% nickel the acoustic emission is characteristic of a brittle deformation. Thus, the monitoring and surveillance system can be tested in either or both situations. In the prior art, synthetic waveform signals were used for such calibration but found not suitable for on-line simulation of the surveillance system. This invention provides an improved system in that it generates true acoustic signals. (author)

  3. Acoustic leak detection in piping systems, 4

    International Nuclear Information System (INIS)

    Kitajima, Akira; Naohara, Nobuyuki; Aihara, Akihiko

    1983-01-01

    To monitor a high-pressure piping of nuclear power plants, a possibility of acoustic leak detection method has been experimentally studied in practical field tests and laboratory tests. Characteristics of background noise in field test and the results of experiment are summarized as follows: (1) The level of background noise in primary loop (PWR) was almost constant under actual plant operation. But it is possible that it rises at the condition of the pressure in primary loop. (2) Based on many experience of laboratory tests and practical field tests. The leak monitoring system for practical field was designed and developed. To improve the reliability, a judgment of leak on this system is used three factors of noise level, duration time of phenomena and frequency spectrum of noise signal emitted from the leak point. (author)

  4. Statistical Modeling of Large-Scale Signal Path Loss in Underwater Acoustic Networks

    Directory of Open Access Journals (Sweden)

    Manuel Perez Malumbres

    2013-02-01

    Full Text Available In an underwater acoustic channel, the propagation conditions are known to vary in time, causing the deviation of the received signal strength from the nominal value predicted by a deterministic propagation model. To facilitate a large-scale system design in such conditions (e.g., power allocation, we have developed a statistical propagation model in which the transmission loss is treated as a random variable. By applying repetitive computation to the acoustic field, using ray tracing for a set of varying environmental conditions (surface height, wave activity, small node displacements around nominal locations, etc., an ensemble of transmission losses is compiled and later used to infer the statistical model parameters. A reasonable agreement is found with log-normal distribution, whose mean obeys a log-distance increases, and whose variance appears to be constant for a certain range of inter-node distances in a given deployment location. The statistical model is deemed useful for higher-level system planning, where simulation is needed to assess the performance of candidate network protocols under various resource allocation policies, i.e., to determine the transmit power and bandwidth allocation necessary to achieve a desired level of performance (connectivity, throughput, reliability, etc..

  5. Acoustic detection of UHE neutrinos in the Mediterranean sea: status and perspective

    Directory of Open Access Journals (Sweden)

    Simeone Francesco

    2017-01-01

    Full Text Available In recent years the astro-particle community is involved in the realization of experimental apparatuses for the detection of high energy neutrinos originated in cosmic sources or produced in the interaction of Cosmic Rays with the Cosmic Microwave Background. For neutrino energies in the TeV-PeV range, optical Cherenkov detectors, that have been so far positively exploited by Baikal[1], IceCube[2] and ANTARES[3], are considered optimal. For higher energies, three different experimental techniques are under study: the detection of radio pulses produced by showers induced by a neutrino interaction, the detection of air showers initiated by neutrinos interacting with rocks or deep Earth’s atmosphere and the detection of acoustic waves produced by deposition of energy following the interaction of neutrinos in an acoustically transparent medium. The potential of the acoustic detection technique, first proposed by Askaryan[4], to build very large neutrino detectors is appealing, thanks to the optimal properties of media such as water or ice as sound propagator. Though the studies on this technique are still in an early stage, acoustic positioning systems used to locate the optical modules in underwater Cherenkov neutrino detectors, give the possibility to study the ambient noise and provide important information for the future analysis of acoustic data.

  6. Signal analysis of steam line acoustics

    International Nuclear Information System (INIS)

    Martin, C. Samuel

    2003-01-01

    upstream and downstream between two locations. The method shows that the direction of the larger magnitude wave -- whether propagating upstream or downstream -- is directly related to the slope of the unwrapped phase angle versus frequency correlation. Indeed, the slope of this line can be related to the acoustic velocity of the wave. The method is then applied to dynamic pressure recordings obtained in a nuclear steam system. Plots of cross-spectra phase versus frequency taken in straight runs of steam piping yield correlations that are nearly linear, and, moreover, the slope of the line is closely related to the acoustic velocity at the corresponding steam pressure. (author)

  7. Investigation of signal models and methods for evaluating structures of processing telecommunication information exchange systems under acoustic noise conditions

    Science.gov (United States)

    Kropotov, Y. A.; Belov, A. A.; Proskuryakov, A. Y.; Kolpakov, A. A.

    2018-05-01

    The paper considers models and methods for estimating signals during the transmission of information messages in telecommunication systems of audio exchange. One-dimensional probability distribution functions that can be used to isolate useful signals, and acoustic noise interference are presented. An approach to the estimation of the correlation and spectral functions of the parameters of acoustic signals is proposed, based on the parametric representation of acoustic signals and the components of the noise components. The paper suggests an approach to improving the efficiency of interference cancellation and highlighting the necessary information when processing signals from telecommunications systems. In this case, the suppression of acoustic noise is based on the methods of adaptive filtering and adaptive compensation. The work also describes the models of echo signals and the structure of subscriber devices in operational command telecommunications systems.

  8. Receptivity of Hypersonic Boundary Layers to Distributed Roughness and Acoustic Disturbances

    Science.gov (United States)

    Balakumar, P.

    2013-01-01

    Boundary-layer receptivity and stability of Mach 6 flows over smooth and rough seven-degree half-angle sharp-tipped cones are numerically investigated. The receptivity of the boundary layer to slow acoustic disturbances, fast acoustic disturbances, and vortical disturbances is considered. The effects of three-dimensional isolated roughness on the receptivity and stability are also simulated. The results for the smooth cone show that the instability waves are generated in the leading edge region and that the boundary layer is much more receptive to slow acoustic waves than to the fast acoustic waves. Vortical disturbances also generate unstable second modes, however the receptivity coefficients are smaller than that of the slow acoustic wave. Distributed roughness elements located near the nose region decreased the receptivity of the second mode generated by the slow acoustic wave by a small amount. Roughness elements distributed across the continuous spectrum increased the receptivity of the second mode generated by the slow and fast acoustic waves and the vorticity wave. The largest increase occurred for the vorticity wave. Roughness elements distributed across the synchronization point did not change the receptivity of the second modes generated by the acoustic waves. The receptivity of the second mode generated by the vorticity wave increased in this case, but the increase is lower than that occurred with the roughness elements located across the continuous spectrum. The simulations with an isolated roughness element showed that the second mode waves generated by the acoustic disturbances are not influenced by the small roughness element. Due to the interaction, a three-dimensional wave is generated. However, the amplitude is orders of magnitude smaller than the two-dimensional wave.

  9. Electricity Generation Characteristics of Energy-Harvesting System with Piezoelectric Element Using Mechanical-Acoustic Coupling

    Directory of Open Access Journals (Sweden)

    Hirotarou Tsuchiya

    2016-01-01

    Full Text Available This paper describes the electricity generation characteristics of a new energy-harvesting system with piezoelectric elements. The proposed system is composed of a rigid cylinder and thin plates at both ends. The piezoelectric elements are installed at the centers of both plates, and one side of each plate is subjected to a harmonic point force. In this system, vibration energy is converted into electrical energy via electromechanical coupling between the plate vibration and piezoelectric effect. In addition, the plate vibration excited by the point force induces a self-sustained vibration at the other plate via mechanical-acoustic coupling between the plate vibrations and an internal sound field into the cylindrical enclosure. Therefore, the electricity generation characteristics should be considered as an electromechanical-acoustic coupling problem. The characteristics are estimated theoretically and experimentally from the electric power in the electricity generation, the mechanical power supplied to the plate, and the electricity generation efficiency that is derived from the ratio of both power. In particular, the electricity generation efficiency is one of the most appropriate factors to evaluate a performance of electricity generation systems. Thus, the effect of mechanical-acoustic coupling is principally evaluated by examining the electricity generation efficiency.

  10. Understanding acoustics an experimentalist’s view of acoustics and vibration

    CERN Document Server

    Garrett, Steven L

    2017-01-01

    This textbook provides a unified approach to acoustics and vibration suitable for use in advanced undergraduate and first-year graduate courses on vibration and fluids. The book includes thorough treatment of vibration of harmonic oscillators, coupled oscillators, isotropic elasticity, and waves in solids including the use of resonance techniques for determination of elastic moduli. Drawing on 35 years of experience teaching introductory graduate acoustics at the Naval Postgraduate School and Penn State, the author presents a hydrodynamic approach to the acoustics of sound in fluids that provides a uniform methodology for analysis of lumped-element systems and wave propagation that can incorporate attenuation mechanisms and complex media. This view provides a consistent and reliable approach that can be extended with confidence to more complex fluids and future applications. Understanding Acoustics opens with a mathematical introduction that includes graphing and statistical uncertainty, followed by five chap...

  11. Tissue-mimicking bladder wall phantoms for evaluating acoustic radiation force-optical coherence elastography systems.

    Science.gov (United States)

    Ejofodomi, O'tega A; Zderic, Vesna; Zara, Jason M

    2010-04-01

    Acoustic radiation force-optical coherence elastography (ARF-OCE) systems are novel imaging systems that have the potential to simultaneously quantify and characterize the optical and mechanical properties of in vivo tissues. This article presents the construction of bladder wall phantoms for use in ARF-OCE systems. Mechanical, acoustic, and optical properties are reported and compared to published values for the urinary bladder. The phantom consisted of 0.2000 +/- 0.0089 and 6.0000 +/- 0.2830 microm polystyrene microspheres (Polysciences Inc., Warrington, PA, Catalog Nos. 07304 and 07312), 7.5 +/- 1.5 microm copolymer microspheres composed of acrylonitrile and vinylidene chloride, (Expancel, Duluth, GA, Catalog No. 461 DU 20), and bovine serum albumin within a gelatin matrix. Young's modulus was measured by successive compression of the phantom and obtaining the slope of the resulting force-displacement data. Acoustic measurements were performed using the transmission method. The phantoms were submerged in a water bath and placed between transmitting and receiving 13 mm diameter unfocused transducers operating at a frequency of 3.5 MHz. A MATLAB algorithm to extract the optical scattering coefficient from optical coherence tomography (OCT) images of the phantom was used. The phantoms possess a Young's modulus of 17.12 +/- 2.72 kPa, a mass density of 1.05 +/- 0.02 g/cm3, an acoustic attenuation coefficient of 0.66 +/- 0.08 dB/cm/MHz, a speed of sound of 1591 +/- 8.76 m/s, and an optical scattering coefficient of 1.80 +/- 0.23 mm(-1). Ultrasound and OCT images of the bladder wall phantom are presented. A material that mimics the mechanical, optical, and acoustic properties of healthy bladder wall has been developed. This tissue-mimicking bladder wall phantom was developed as a control tool to investigate the feasibility of using ARF-OCE to detect the mechanical and optical changes that may be indicative of the onset or development of cancer in the urinary bladder

  12. A Wireless Location System in LTE Networks

    OpenAIRE

    Liu, Qi; Hu, Rongyi; Liu, Shan

    2017-01-01

    Personal location technologies are becoming important with the rapid development of Mobile Internet services. In traditional cellular networks, the key problems of user location technologies are high-precision synchronization among different base stations, inflexible processing resources, and low accuracy positioning, especially for indoor environment. In this paper, a new LTE location system in Centralized Radio Access Network (C-RAN) is proposed, which makes channel and location measurement...

  13. Locating Objects in Wide-Area Systems

    NARCIS (Netherlands)

    Steen, M. van; Hauck, F.J.; Homburg, P.; Tanenbaum, A.S.

    Locating mobile objects in a worldwide system requires a scalable location service. An object can be a telephone or a notebook computer, but also a software or data object, such as a file or an electronic document. Our service strictly separates an object's name from the addresses where it can be

  14. Developments in acoustic emission for application to nuclear reactor systems

    International Nuclear Information System (INIS)

    Bentley, P.G.

    1982-01-01

    Developments in acoustic emission are summarised as they relate to the principal applications to nuclear reactors, and light water reactor pressure vessels in particular. Improvement in the understanding of acoustic emission has come from materials tests and these confirm the problems in applying the technique for in-service or periodic proof test monitoring of growing fatique cracks. Applications in LMFBR have confirmed that acoustic emission can be applied in the nuclear environment and the detection of stress corrosion cracking in both BWR and LMFBR seems possible. Some information is included on the developing interest in applying the techniques of acoustic emission for leak detection during shop hydro and in-service monitoring. Acoustic emission is also being developed for weld fabrication monitoring and recently introduced pattern recognition techniques are having a significant impact in this application. (author)

  15. An algorithm for leak locating using coupled vibration of pipe-water

    International Nuclear Information System (INIS)

    Lee, Young Sup; Yoon, Dong Jin

    2004-01-01

    Leak noise is a good source to identify the exact location of a leak point of underground water pipelines. Water leak generates broadband sound from a leak location and this sound propagation due to leak in water pipelines is not a non-dispersive wave any more because of the surrounding pipes and soil. However, the necessity of long-range detection of this leak location makes to identify low-frequency acoustic waves rather than high frequency ones. Acoustic wave propagation coupled with surrounding boundaries including cast iron pipes is theoretically analyzed and the wave velocity was confirmed with experiment. The leak locations were identified both by the Acoustic Emission (AE) method and the cross-correlation method. In a short-range distance, both the AE method and cross-correlation method are effective to detect leak position. However, the detection for a long-range distance required a lower frequency range accelerometers only because higher frequency waves were attenuated very quickly with the increase of propagation paths. Two algorithms for the cross-correlation function were suggested, and a long-range detection has been achieved at real underground water pipelines longer than 300m

  16. Department of Cybernetic Acoustics

    Science.gov (United States)

    The development of the theory, instrumentation and applications of methods and systems for the measurement, analysis, processing and synthesis of acoustic signals within the audio frequency range, particularly of the speech signal and the vibro-acoustic signal emitted by technical and industrial equipments treated as noise and vibration sources was discussed. The research work, both theoretical and experimental, aims at applications in various branches of science, and medicine, such as: acoustical diagnostics and phoniatric rehabilitation of pathological and postoperative states of the speech organ; bilateral ""man-machine'' speech communication based on the analysis, recognition and synthesis of the speech signal; vibro-acoustical diagnostics and continuous monitoring of the state of machines, technical equipments and technological processes.

  17. The Research on Improved Companding Transformation for Reducing PAPR in Underwater Acoustic OFDM Communication System

    Directory of Open Access Journals (Sweden)

    Jinqiu Wu

    2016-01-01

    Full Text Available To solve the problem of the high peak-to-average power ratio (PAPR in Orthogonal Frequency Division Multiplexing (OFDM for the underwater acoustic communication system, the paper offers a method of reducing PAPR which combines the amplitude limiting and the improved nonlinear transformation. Traditional amplitude limiting technique can reduce PAPR in OFDM system effectively, at the cost of reducing the bit error rate (BER. However the companding transformation has far less computation complexity than SLM or PTS technologies and can improve the BER performance compared to the amplitude limiting technique simultaneously. The paper combines these two kinds of techniques, takes full use of advantages of the two method, and puts forward a low-complexity scheme choosing parameters that are more appropriate to the underwater acoustic field, with the result of improved BER performance even in lower SNR. Both simulation and experiment results show that the new method which combines clipping and companding transformation can effectively reduce the PAPR in the underwater acoustic OFDM communication system and improve the BER performance simultaneously.

  18. Mapping thunder sources by inverting acoustic and electromagnetic observations

    Science.gov (United States)

    Anderson, J. F.; Johnson, J. B.; Arechiga, R. O.; Thomas, R. J.

    2014-12-01

    We present a new method of locating current flow in lightning strikes by inversion of thunder recordings constrained by Lightning Mapping Array observations. First, radio frequency (RF) pulses are connected to reconstruct conductive channels created by leaders. Then, acoustic signals that would be produced by current flow through each channel are forward modeled. The recorded thunder is considered to consist of a weighted superposition of these acoustic signals. We calculate the posterior distribution of acoustic source energy for each channel with a Markov Chain Monte Carlo inversion that fits power envelopes of modeled and recorded thunder; these results show which parts of the flash carry current and produce thunder. We examine the effects of RF pulse location imprecision and atmospheric winds on quality of results and apply this method to several lightning flashes over the Magdalena Mountains in New Mexico, USA. This method will enable more detailed study of lightning phenomena by allowing researchers to map current flow in addition to leader propagation.

  19. Acoustic characteristics of the vowel systems of six regional varieties of American English

    Science.gov (United States)

    Clopper, Cynthia G.; Pisoni, David B.; de Jong, Kenneth

    2012-01-01

    Previous research by speech scientists on the acoustic characteristics of American English vowel systems has typically focused on a single regional variety, despite decades of sociolinguistic research demonstrating the extent of regional phonological variation in the United States. In the present study, acoustic measures of duration and first and second formant frequencies were obtained from five repetitions of 11 different vowels produced by 48 talkers representing both genders and six regional varieties of American English. Results revealed consistent variation due to region of origin, particularly with respect to the production of low vowels and high back vowels. The Northern talkers produced shifted low vowels consistent with the Northern Cities Chain Shift, the Southern talkers produced fronted back vowels consistent with the Southern Vowel Shift, and the New England, Midland, and Western talkers produced the low back vowel merger. These findings indicate that the vowel systems of American English are better characterized in terms of the region of origin of the talkers than in terms of a single set of idealized acoustic-phonetic baselines of “General” American English and provide benchmark data for six regional varieties. PMID:16240825

  20. Design of a TDOA location engine and development of a location system based on chirp spread spectrum.

    Science.gov (United States)

    Wang, Rui-Rong; Yu, Xiao-Qing; Zheng, Shu-Wang; Ye, Yang

    2016-01-01

    Location based services (LBS) provided by wireless sensor networks have garnered a great deal of attention from researchers and developers in recent years. Chirp spread spectrum (CSS) signaling formatting with time difference of arrival (TDOA) ranging technology is an effective LBS technique in regards to positioning accuracy, cost, and power consumption. The design and implementation of the location engine and location management based on TDOA location algorithms were the focus of this study; as the core of the system, the location engine was designed as a series of location algorithms and smoothing algorithms. To enhance the location accuracy, a Kalman filter algorithm and moving weighted average technique were respectively applied to smooth the TDOA range measurements and location results, which are calculated by the cooperation of a Kalman TDOA algorithm and a Taylor TDOA algorithm. The location management server, the information center of the system, was designed with Data Server and Mclient. To evaluate the performance of the location algorithms and the stability of the system software, we used a Nanotron nanoLOC Development Kit 3.0 to conduct indoor and outdoor location experiments. The results indicated that the location system runs stably with high accuracy at absolute error below 0.6 m.

  1. Subjective evaluation of restaurant acoustics in a virtual sound environment

    DEFF Research Database (Denmark)

    Nielsen, Nicolaj Østergaard; Marschall, Marton; Santurette, Sébastien

    2016-01-01

    Many restaurants have smooth rigid surfaces made of wood, steel, glass, and concrete. This often results in a lack of sound absorption. Such restaurants are notorious for high sound noise levels during service that most owners actually desire for representing vibrant eating environments, although...... surveys report that noise complaints are on par with poor service. This study investigated the relation between objective acoustic parameters and subjective evaluation of acoustic comfort at five restaurants in terms of three parameters: noise annoyance, speech intelligibility, and privacy. At each...... location, customers filled out questionnaire surveys, acoustic parameters were measured, and recordings of restaurant acoustic scenes were obtained with a 64-channel spherical array. The acoustic scenes were reproduced in a virtual sound environment (VSE) with 64 loudspeakers placed in an anechoic room...

  2. TU-F-CAMPUS-I-04: Head-Only Asymmetric Gradient System Evaluation: ACR Image Quality and Acoustic Noise

    Energy Technology Data Exchange (ETDEWEB)

    Weavers, P; Shu, Y; Tao, S; Bernstein, M [Mayo Clinic, Rochester, Minnesota (United States); Lee, S; Piel, J; Foo, T [GE Global Research, Niskayuna, NY (United States); Mathieu, J-B [GE Healthcare, Florence, SC (Italy)

    2015-06-15

    Purpose: A high-performance head-only magnetic resonance imaging gradient system with an acquisition volume of 26 cm employing an asymmetric design for the transverse coils has been developed. It is able to reach a magnitude of 85 mT/m at a slew rate of 700 T/m/s, but operated at 80 mT/m and 500 T/m/s for this test. A challenge resulting from this asymmetric design is that the gradient nonlinearly exhibits both odd- and even-ordered terms, and as the full imaging field of view is often used, the nonlinearity is pronounced. The purpose of this work is to show the system can produce clinically useful images after an on-site gradient nonlinearity calibration and correction, and show that acoustic noise levels fall within non-significant risk (NSR) limits for standard clinical pulse sequences. Methods: The head-only gradient system was inserted into a standard 3T wide-bore scanner without acoustic damping. The ACR phantom was scanned in an 8-channel receive-only head coil and the standard American College of Radiology (ACR) MRI quality control (QC) test was performed. Acoustic noise levels were measured for several standard pulse sequences. Results: Images acquired with the head-only gradient system passed all ACR MR image quality tests; Both even and odd-order gradient distortion correction terms were required for the asymmetric gradients to pass. Acoustic noise measurements were within FDA NSR guidelines of 99 dBA (with assumed 20 dBA hearing protection) A-weighted and 140 dB for peak for all but one sequence. Note the gradient system was installed without any shroud or acoustic batting. We expect final system integration to greatly reduce noise experienced by the patient. Conclusion: A high-performance head-only asymmetric gradient system operating at 80 mT/m and 500 T/m/s conforms to FDA acoustic noise limits in all but one case, and passes all the ACR MR image quality control tests. This work was supported in part by the NIH grant 5R01EB010065.

  3. TU-F-CAMPUS-I-04: Head-Only Asymmetric Gradient System Evaluation: ACR Image Quality and Acoustic Noise

    International Nuclear Information System (INIS)

    Weavers, P; Shu, Y; Tao, S; Bernstein, M; Lee, S; Piel, J; Foo, T; Mathieu, J-B

    2015-01-01

    Purpose: A high-performance head-only magnetic resonance imaging gradient system with an acquisition volume of 26 cm employing an asymmetric design for the transverse coils has been developed. It is able to reach a magnitude of 85 mT/m at a slew rate of 700 T/m/s, but operated at 80 mT/m and 500 T/m/s for this test. A challenge resulting from this asymmetric design is that the gradient nonlinearly exhibits both odd- and even-ordered terms, and as the full imaging field of view is often used, the nonlinearity is pronounced. The purpose of this work is to show the system can produce clinically useful images after an on-site gradient nonlinearity calibration and correction, and show that acoustic noise levels fall within non-significant risk (NSR) limits for standard clinical pulse sequences. Methods: The head-only gradient system was inserted into a standard 3T wide-bore scanner without acoustic damping. The ACR phantom was scanned in an 8-channel receive-only head coil and the standard American College of Radiology (ACR) MRI quality control (QC) test was performed. Acoustic noise levels were measured for several standard pulse sequences. Results: Images acquired with the head-only gradient system passed all ACR MR image quality tests; Both even and odd-order gradient distortion correction terms were required for the asymmetric gradients to pass. Acoustic noise measurements were within FDA NSR guidelines of 99 dBA (with assumed 20 dBA hearing protection) A-weighted and 140 dB for peak for all but one sequence. Note the gradient system was installed without any shroud or acoustic batting. We expect final system integration to greatly reduce noise experienced by the patient. Conclusion: A high-performance head-only asymmetric gradient system operating at 80 mT/m and 500 T/m/s conforms to FDA acoustic noise limits in all but one case, and passes all the ACR MR image quality control tests. This work was supported in part by the NIH grant 5R01EB010065

  4. Active field control (AFC) -electro-acoustic enhancement system using acoustical feedback control

    Science.gov (United States)

    Miyazaki, Hideo; Watanabe, Takayuki; Kishinaga, Shinji; Kawakami, Fukushi

    2003-10-01

    AFC is an electro-acoustic enhancement system using FIR filters to optimize auditory impressions, such as liveness, loudness, and spaciousness. This system has been under development at Yamaha Corporation for more than 15 years and has been installed in approximately 50 venues in Japan to date. AFC utilizes feedback control techniques for recreation of reverberation from the physical reverberation of the room. In order to prevent coloration problems caused by a closed loop condition, two types of time-varying control techniques are implemented in the AFC system to ensure smooth loop gain and a sufficient margin in frequency characteristics to prevent instability. Those are: (a) EMR (electric microphone rotator) -smoothing frequency responses between microphones and speakers by changing the combinations of inputs and outputs periodically; (b) fluctuating-FIR -smoothing frequency responses of FIR filters and preventing coloration problems caused by fixed FIR filters, by moving each FIR tap periodically on time axis with a different phase and time period. In this paper, these techniques are summarized. A block diagram of AFC using new equipment named AFC1, which has been developed at Yamaha Corporation and released recently in the US, is also presented.

  5. Surface acoustic wave dust deposition monitor

    Science.gov (United States)

    Fasching, G.E.; Smith, N.S. Jr.

    1988-02-12

    A system is disclosed for using the attenuation of surface acoustic waves to monitor real time dust deposition rates on surfaces. The system includes a signal generator, a tone-burst generator/amplifier connected to a transmitting transducer for converting electrical signals into acoustic waves. These waves are transmitted through a path defining means adjacent to a layer of dust and then, in turn, transmitted to a receiving transducer for changing the attenuated acoustic wave to electrical signals. The signals representing the attenuated acoustic waves may be amplified and used in a means for analyzing the output signals to produce an output indicative of the dust deposition rates and/or values of dust in the layer. 8 figs.

  6. Acoustic loading effects on oscillating rod bundles

    International Nuclear Information System (INIS)

    Lin, W.H.

    1980-01-01

    An analytical study of the interaction between an infinite acoustic medium and a cluster of circular rods is described. The acoustic field due to oscillating rods and the acoustic loading on the rods are first solved in a closed form. The acoustic loading is then used as a forcing function for rod responses, and the acousto-elastic couplings are solved simultaneously. Numerical examples are presented for several cases to illustrate the effects of various system parameters on the acoustic reaction force coefficients. The effect of the acoustic loading on the coupled eigenfrequencies are discussed

  7. Determination of the viscous acoustic field for liquid drop positioning/forcing in an acoustic levitation chamber in microgravity

    Science.gov (United States)

    Lyell, Margaret J.

    1992-01-01

    The development of acoustic levitation systems has provided a technology with which to undertake droplet studies as well as do containerless processing experiments in a microgravity environment. Acoustic levitation chambers utilize radiation pressure forces to position/manipulate the drop. Oscillations can be induced via frequency modulation of the acoustic wave, with the modulated acoustic radiation vector acting as the driving force. To account for tangential as well as radial forcing, it is necessary that the viscous effects be included in the acoustic field. The method of composite expansions is employed in the determination of the acoustic field with viscous effects.

  8. Levitation With a Single Acoustic Driver

    Science.gov (United States)

    Barmatz, M. B.; Gaspar, M. S.; Allen, J. L.

    1986-01-01

    Pair of reports describes acoustic-levitation systems in which only one acoustic resonance mode excited, and only one driver needed. Systems employ levitation chambers of rectangular and cylindrical geometries. Reports first describe single mode concept and indicate which modes used to levitate sample without rotation. Reports then describe systems in which controlled rotation of sample introduced.

  9. AE source location by neural networks with arrival time profiles

    Czech Academy of Sciences Publication Activity Database

    Chlada, Milan; Blaháček, Michal; Převorovský, Zdeněk

    2009-01-01

    Roč. 19, č. 2 (2009), s. 4-4 ISSN 1213-3825. [NDT in PROGRESS. 12.11.2009-14.11.2009, Praha] R&D Projects: GA ČR GA101/07/1518; GA ČR GA106/07/1393 Institutional research plan: CEZ:AV0Z20760514 Keywords : acoustic emission * source location * artificial neural networks Subject RIV: BI - Acoustics www.cndt.cz

  10. Smart intimation and location of faults in distribution system

    Science.gov (United States)

    Hari Krishna, K.; Srinivasa Rao, B.

    2018-04-01

    Location of faults in the distribution system is one of the most complicated problems that we are facing today. Identification of fault location and severity of fault within a short time is required to provide continuous power supply but fault identification and information transfer to the operator is the biggest challenge in the distribution network. This paper proposes a fault location method in the distribution system based on Arduino nano and GSM module with flame sensor. The main idea is to locate the fault in the distribution transformer by sensing the arc coming out from the fuse element. The biggest challenge in the distribution network is to identify the location and the severity of faults under different conditions. Well operated transmission and distribution systems will play a key role for uninterrupted power supply. Whenever fault occurs in the distribution system the time taken to locate and eliminate the fault has to be reduced. The proposed design was achieved with flame sensor and GSM module. Under faulty condition, the system will automatically send an alert message to the operator in the distribution system, about the abnormal conditions near the transformer, site code and its exact location for possible power restoration.

  11. Acoustic communication in plant-animal interactions.

    Science.gov (United States)

    Schöner, Michael G; Simon, Ralph; Schöner, Caroline R

    2016-08-01

    Acoustic communication is widespread and well-studied in animals but has been neglected in other organisms such as plants. However, there is growing evidence for acoustic communication in plant-animal interactions. While knowledge about active acoustic signalling in plants (i.e. active sound production) is still in its infancy, research on passive acoustic signalling (i.e. reflection of animal sounds) revealed that bat-dependent plants have adapted to the bats' echolocation systems by providing acoustic reflectors to attract their animal partners. Understanding the proximate mechanisms and ultimate causes of acoustic communication will shed light on an underestimated dimension of information transfer between plants and animals. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. A Preliminary Study Application Clustering System in Acoustic Emission Monitoring

    Directory of Open Access Journals (Sweden)

    Saiful Bahari Nur Amira Afiza

    2017-01-01

    Full Text Available Acoustic Emission (AE is a non-destructive testing known as assessment on damage detection in structural engineering. It also can be used to discriminate the different types of damage occurring in a composite materials. The main problem associated with the data analysis is the discrimination between the different AE sources and analysis of the AE signal in order to identify the most critical damage mechanism. Clustering analysis is a technique in which the set of object are assigned to a group called cluster. The objective of the cluster analysis is to separate a set of data into several classes that reflect the internal structure of data. In this paper was used k-means algorithm for partitioned clustering method, numerous effort have been made to improve the performance of application k-means clustering algorithm. This paper presents a current review on application clustering system in Acoustic Emission.

  13. Influence of acoustic dominant mode propagation in a trifurcated lined duct with different impedances

    International Nuclear Information System (INIS)

    Ayub, M; Tiwana, M H; Mann, A B

    2010-01-01

    In this study, we analyzed the diffraction of the acoustic dominant mode in a parallel-plate trifurcated waveguide with normal impedance boundary conditions in the case where surface impedances of the upper and lower infinite plates are different from each other. The acoustic dominant mode is incident in a soft/hard semi-infinite duct located symmetrically in the infinite lined duct. The solution of the boundary value problem using Fourier transform leads to two simultaneous modified Wiener-Hopf equations that are uncoupled using the pole removal technique. Two infinite sets of unknown coefficients are involved in the solution, which satisfy two infinite systems of linear algebraic equations. These systems are solved numerically. The new kernel functions are factorized. Some graphical results showing the influence of sundry parameters of interest on the reflection coefficient are presented.

  14. Acoustic emission measurement on large scale coils at JAERI

    International Nuclear Information System (INIS)

    Yoshida, K.; Hattori, Y.; Nishi, M.F.; Shimamoto, S.; Tsuji, H.

    1986-01-01

    The objective of acoustic emission measurement at Japan Atomic Energy Research Institute (JAERI) is an establishment of a general diagnostic method for superconducting magnet systems. Output of strain and displacement gages can not cover a whole system in monitoring premonitory phenomena of a magnet system s failure, because these sensors are mounted on points and therefore localized. Acoustic emissions can be transmitted to sensors through structural materials without electrical noise. Monitoring of acoustic emission will be one of the methods to predict a serious failure of magnet systems in a vacuum vessel. For this purpose, several sensors were installed on the Japanese LCT coil and the Test Module Coil (TMC). Some of acoustic activity was similar as seen in these coils. The correlation between voltage spikes and acoustic events is excellent during single coil charging mode, but poorer during out of plane force mode. There are no indicative acoustical phenomena before a magnet quench or during normal zone generation. The conditioning of acoustic events and voltage spikes can be seen after any cooling down. The localization of electrical insulation damage with the acoustic emission technique is one of its most useful applications

  15. Data Center Equipment Location and Monitoring System

    DEFF Research Database (Denmark)

    2013-01-01

    Abstract: Data center equipment location systems include hardware and software to provide information on the location, monitoring, and security of servers and other equipment in equipment racks. The systems provide a wired alternative to the wireless RFID tag system by using electronic ID tags...... connected to each piece of equipment, each electronic ID tag connected directly by wires to an equipment rack controller on the equipment rack. The equipment rack controllers link to a central control computer that provides an operator ...

  16. Acoustic biosensors.

    Science.gov (United States)

    Fogel, Ronen; Limson, Janice; Seshia, Ashwin A

    2016-06-30

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. © 2016 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  17. The effect of reflections on the performance of an acoustic energy transfer system

    NARCIS (Netherlands)

    Roes, M.G.L.; Hendrix, M.A.M.; Duarte, J.L.

    2012-01-01

    Abstract—The performance of an acoustic energy transfer (AET) system, defined as the ratio of electrical output to input power, is affected to a large extent by reflections. Their effect is examined in this paper. A finite element model is created to model reflections in a typical AET system, of

  18. Acoustic Source Localization and Beamforming: Theory and Practice

    Directory of Open Access Journals (Sweden)

    Chen Joe C

    2003-01-01

    Full Text Available We consider the theoretical and practical aspects of locating acoustic sources using an array of microphones. A maximum-likelihood (ML direct localization is obtained when the sound source is near the array, while in the far-field case, we demonstrate the localization via the cross bearing from several widely separated arrays. In the case of multiple sources, an alternating projection procedure is applied to determine the ML estimate of the DOAs from the observed data. The ML estimator is shown to be effective in locating sound sources of various types, for example, vehicle, music, and even white noise. From the theoretical Cramér-Rao bound analysis, we find that better source location estimates can be obtained for high-frequency signals than low-frequency signals. In addition, large range estimation error results when the source signal is unknown, but such unknown parameter does not have much impact on angle estimation. Much experimentally measured acoustic data was used to verify the proposed algorithms.

  19. Airborne DoA estimation of gunshot acoustic signals using drones with application to sniper localization systems

    Science.gov (United States)

    Fernandes, Rigel P.; Ramos, António L. L.; Apolinário, José A.

    2017-05-01

    Shooter localization systems have been subject of a growing attention lately owing to its wide span of possible applications, e.g., civil protection, law enforcement, and support to soldiers in missions where snipers might pose a serious threat. These devices are based on the processing of electromagnetic or acoustic signatures associated with the firing of a gun. This work is concerned with the latter, where the shooter's position can be obtained based on the estimation of the direction-of-arrival (DoA) of the acoustic components of a gunshot signal (muzzle blast and shock wave). A major limitation of current commercially available acoustic sniper localization systems is the impossibility of finding the shooter's position when one of these acoustic signatures is not detected. This is very likely to occur in real-life situations, especially when the microphones are not in the field of view of the shockwave or when the presence of obstacles like buildings can prevent a direct-path to sensors. This work addresses the problem of DoA estimation of the muzzle blast using a planar array of sensors deployed in a drone. Results supported by actual gunshot data from a realistic setup are very promising and pave the way for the development of enhanced sniper localization systems featuring two main advantages over stationary ones: (1) wider surveillance area; and (2) increased likelihood of a direct-path detection of at least one of the gunshot signals, thereby adding robustness and reliability to the system.

  20. Open Location Management in Automated Warehousing Systems

    OpenAIRE

    Yu, Yugang; Koster, René

    2009-01-01

    textabstractA warehouse needs to have sufficient open locations to be able to store incoming shipments of various sizes. In combination with ongoing load retrievals open locations gradually spread over the storage area. Unfavorable positions of open locations negatively impact the average load retrieval times. This paper presents a new method to manage these open locations such that the average system travel time for processing a block of storage and retrieval jobs in an automated warehousing...

  1. Hybrid acoustic energy harvesting using combined electromagnetic and piezoelectric conversion

    Science.gov (United States)

    Khan, Farid Ullah; Izhar

    2016-02-01

    This paper reports a novel hybrid acoustic energy harvester. The harvester utilizes both the electromagnetic and piezoelectric conversion mechanisms simultaneously to convert the ambient acoustical noise into electrical power for self-powered wireless sensor nodes. The proposed harvester is comprised of a Helmholtz resonator, two magnets mounted on a piezoelectric plate, and a wound coil located under the magnets. The harvester is characterized both under harmonic and real random acoustical excitations. In-lab, under harmonic acoustical excitation at a sound pressure level of 130 dB and frequency of 2.1 kHz, an optimum power of 2.86 μW (at 114 Ω optimum load) is obtained from electromagnetic conversion and 50 μW (at 1000 Ω optimum load) is generated by the piezoelectric harvester's part. Moreover, in real acoustical environment of a domestic electric generator the peak voltages of 40 and 123 mV are produced by the electromagnetic and piezoelectric portions of the acoustic energy harvester.

  2. Examining the plankton acoustic response with a vessel mounted ADCP across oceanic fronts located in the Drake Passage

    Directory of Open Access Journals (Sweden)

    Silvia Blanc

    2008-12-01

    Full Text Available On December 2001 and January 2006, during the LMG01-9 and LMG06-1 cruises to Antarctic Peninsula, at-sea oceanographic and acoustic measurements were conducted onboard the R/V L. M. Gould icebreaker along two transects located between (55.15 °S, 65 ºW and (64.65 °S, 65 ºW and between (55.15 ºS, 64.91 ºW and (62.7 ºS, 62.21 ºW, respectively. The scientific crew consisted of researchers from two US institutes, and a scientific observer from the Argentinean Naval Service of Research & Development under the frame of the US National Science Foundation Antarctic Program. The present work accomplishes an alternative application for a vesselmounted Acoustic Doppler Current Profiler (ADCP with an operating frequency of 153.6 kHz. Volume Acoustic Backscattering Strengths, S V, were computed from the recorded ADCP's voltages. The obtained values fell in a range of -92 dB to -62 dB, for the layer of the water column comprised between 26 m - 300 m on 2001 and in the range of -93 dB to -58 dB for the water column between 22 m - 300 m on 2006. Depth-averaged, S V, for the upper water column (about the first 150 m on experiment transects were computed as well as S V values averaged in depth and latitude. Data processing revealed interesting features about the upper ocean acoustic behaviour. On December 2001, a significant non-uniform scattering response in the ensonified water column with quite high values of S V, associated with the diel vertical migration, was obtained. Additionally, a remarkable increment in the scattering response was observed at the estimated location of the Antarctic Divergence (AD. This feature was also observed on January 2006 in addition to remarkable high values of S V, in coastal waters of the Antarctic Peninsula. Plotting and exhaustive analyses of S V (z profiles enabled the visualisation of three distinct types of qualitative patterns, namely, curves with: (I two observable maxima, (II only one maximum, (III a depth

  3. An acoustic vector based approach to locate low frequency noise sources in 3D

    NARCIS (Netherlands)

    Bree, H.-E. de; Ostendorf, C.; Basten, T.

    2009-01-01

    Although low frequency noise is an issue of huge societal importance, traditional acoustic testing methods have limitations in finding the low frequency source. It is hard to determine the direction of the noise using traditional microphones. Three dimensional sound probes capturing the particle

  4. An analytical and experimental investigation of active structural acoustic control of noise transmission through double panel systems

    Science.gov (United States)

    Carneal, James P.; Fuller, Chris R.

    2004-05-01

    An analytical and experimental investigation of active control of sound transmission through double panel systems has been performed. The technique used was active structural acoustic control (ASAC) where the control inputs, in the form of piezoelectric actuators, were applied to the structure while the radiating pressure field was minimized. Results verify earlier experimental investigations and indicate the application of control inputs to the radiating panel of the double panel system resulted in greater transmission loss (TL) due to its direct effect on the nature of the structural-acoustic (or radiation) coupling between the radiating panel and the receiving acoustic space. Increased control performance was seen in a double panel system consisting of a stiffer radiating panel due to its lower modal density and also as a result of better impedance matching between the piezoelectric actuator and the radiating plate. In general the results validate the ASAC approach for double panel systems, demonstrating that it is possible to take advantage of double panel system passive behavior to enhance control performance, and provide design guidelines.

  5. Acoustic Characterization of Mesoscale Objects

    Energy Technology Data Exchange (ETDEWEB)

    Chinn, D; Huber, R; Chambers, D; Cole, G; Balogun, O; Spicer, J; Murray, T

    2007-03-13

    This report describes the science and engineering performed to provide state-of-the-art acoustic capabilities for nondestructively characterizing mesoscale (millimeter-sized) objects--allowing micrometer resolution over the objects entire volume. Materials and structures used in mesoscale objects necessitate the use of (1) GHz acoustic frequencies and (2) non-contacting laser generation and detection of acoustic waves. This effort demonstrated that acoustic methods at gigahertz frequencies have the necessary penetration depth and spatial resolution to effectively detect density discontinuities, gaps, and delaminations. A prototype laser-based ultrasonic system was designed and built. The system uses a micro-chip laser for excitation of broadband ultrasonic waves with frequency components reaching 1.0 GHz, and a path-stabilized Michelson interferometer for detection. The proof-of-concept for mesoscale characterization is demonstrated by imaging a micro-fabricated etched pattern in a 70 {micro}m thick silicon wafer.

  6. Magnetoactive Acoustic Metamaterials.

    Science.gov (United States)

    Yu, Kunhao; Fang, Nicholas X; Huang, Guoliang; Wang, Qiming

    2018-04-11

    Acoustic metamaterials with negative constitutive parameters (modulus and/or mass density) have shown great potential in diverse applications ranging from sonic cloaking, abnormal refraction and superlensing, to noise canceling. In conventional acoustic metamaterials, the negative constitutive parameters are engineered via tailored structures with fixed geometries; therefore, the relationships between constitutive parameters and acoustic frequencies are typically fixed to form a 2D phase space once the structures are fabricated. Here, by means of a model system of magnetoactive lattice structures, stimuli-responsive acoustic metamaterials are demonstrated to be able to extend the 2D phase space to 3D through rapidly and repeatedly switching signs of constitutive parameters with remote magnetic fields. It is shown for the first time that effective modulus can be reversibly switched between positive and negative within controlled frequency regimes through lattice buckling modulated by theoretically predicted magnetic fields. The magnetically triggered negative-modulus and cavity-induced negative density are integrated to achieve flexible switching between single-negative and double-negative. This strategy opens promising avenues for remote, rapid, and reversible modulation of acoustic transportation, refraction, imaging, and focusing in subwavelength regimes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Internal Acoustics of the ISS and Other Spacecraft

    Science.gov (United States)

    Allen, Christopher S.

    2017-01-01

    It is important to control the acoustic environment inside spacecraft and space habitats to protect for astronaut communications, alarm audibility, and habitability, and to reduce astronauts' risk for sleep disturbance, and hear-ing loss. But this is not an easy task, given the various design trade-offs, and it has been difficult, historically, to achieve. Over time it has been found that successful control of spacecraft acoustic levels is achieved by levying firm requirements at the system-level, using a systems engineering approach for design and development, and then validating these requirements with acoustic testing. In the systems engineering method, the system-level requirements must be flowed down to sub-systems and component noise sources, using acoustic analysis and acoustic modelling to develop allocated requirements for the sub-systems and components. Noise controls must also be developed, tested, and implemented so the sub-systems and components can achieve their allocated limits. It is also important to have management support for acoustics efforts to maintain their priority against the various trade-offs, including mass, volume, power, cost, and schedule. In this extended abstract and companion presentation, the requirements, approach, and results for controlling acoustic levels in most US spacecraft since Apollo will be briefly discussed. The approach for controlling acoustic levels in the future US space vehicle, Orion Multipurpose Crew Vehicle (MPCV), will also be briefly discussed. These discussions will be limited to the control of continuous noise inside the space vehicles. Other types of noise, such as launch, landing, and abort noise, intermittent noise, Extra-Vehicular Activity (EVA) noise, emergency operations/off-nominal noise, noise exposure, and impulse noise are important, but will not be discussed because of time limitations.

  8. Acoustic-Modal Testing of the Ares I Launch Abort System Attitude Control Motor Valve

    Science.gov (United States)

    Davis, R. Benjamin; Fischbach, Sean R.

    2010-01-01

    The Attitude Control Motor (ACM) is being developed for use in the Launch Abort System (LAS) of NASA's Ares I launch vehicle. The ACM consists of a small solid rocket motor and eight actuated pintle valves that directionally allocate.thrust_- 1t.has-been- predicted-that significant unsteady. pressure.fluctuations.will.exist. inside the-valves during operation. The dominant frequencies of these oscillations correspond to the lowest several acoustic natural frequencies of the individual valves. An acoustic finite element model of the fluid volume inside the valve has been critical to the prediction of these frequencies and their associated mode shapes. This work describes an effort to experimentally validate the acoustic finite model of the valve with an acoustic modal test. The modal test involved instrumenting a flight-like valve with six microphones and then exciting the enclosed air with a loudspeaker. The loudspeaker was configured to deliver broadband noise at relatively high sound pressure levels. The aquired microphone signals were post-processed and compared to results generated from the acoustic finite element model. Initial comparisons between the test data and the model results revealed that additional model refinement was necessary. Specifically, the model was updated to implement a complex impedance boundary condition at the entrance to the valve supply tube. This boundary condition models the frequency-dependent impedance that an acoustic wave will encounter as it reaches the end of the supply tube. Upon invoking this boundary condition, significantly improved agreement between the test data and the model was realized.

  9. Evidence-based cross validation for acoustic power transmission for a novel treatment system.

    Science.gov (United States)

    Mihcin, Senay; Strehlow, Jan; Demedts, Daniel; Schwenke, Michael; Levy, Yoav; Melzer, Andreas

    2017-06-01

    The novel Trans-Fusimo Treatment System (TTS) is designed to control Magnetic Resonance guided Focused Ultrasound (MRgFUS) therapy to ablate liver tumours under respiratory motion. It is crucial to deliver the acoustic power within tolerance limits for effective liver tumour treatment via MRgFUS. Before application in a clinical setting, evidence of reproducibility and reliability is a must for safe practice. The TTS software delivers the acoustic power via ExAblate-2100 Conformal Bone System (CBS) transducer. A built-in quality assurance application was developed to measure the force values, using a novel protocol to measure the efficiency for the electrical power values of 100 and 150W for 6s of sonication. This procedure was repeated 30 times by two independent users against the clinically approved ExAblate-2100 CBS for cross-validation. Both systems proved to deliver the power within the accepted efficiency levels (70-90%). Two sample t-tests were used to assess the differences in force values between the ExAblate-2100 CBS and the TTS (p > 0.05). Bland-Altman plots were used to demonstrate the limits of agreement between the two systems falling within the 10% limits of agreement. Two sample t-tests indicated that TTS does not have user dependency (p > 0.05). The TTS software proved to deliver the acoustic power without exceeding the safety levels. Results provide evidence as a part of ISO13485 regulations for CE marking purposes. The developed methodology could be utilised as a part of quality assurance system in clinical settings; when the TTS is used in clinical practice.

  10. A Summary of NASA Research Exploring the Acoustics of Small Unmanned Aerial Systems

    Science.gov (United States)

    Zawodny, Nikolas S.; Christian, Andrew; Cabell, Randolph

    2018-01-01

    Proposed uses of small unmanned aerial systems (sUAS) have the potential to expose large portions of communities to a new noise source. In order to understand the potential noise impact of sUAS, NASA initiated acoustics research as one component of the 3-year DELIVER project, with the goal of documenting the feasibility of using existing aircraft design tools and methods on this class of vehicles. This paper summarizes the acoustics research conducted within the DELIVER project. The research described here represents an initial study, and subsequent research building on the findings of this work has been proposed for other NASA projects. The paper summarizes acoustics research in four areas: measurements of noise generated by flyovers of small unmanned aerial vehicles, measurements in controlled test facilities to understand the noise generated by components of these vehicles, computational predictions of component and full vehicle noise, and psychoacoustic tests including auralizations conducted to assess human annoyance to the noise generated by these vehicles.

  11. Characterization of microchannel anechoic corners formed by surface acoustic waves

    Science.gov (United States)

    Destgeer, Ghulam; Alam, Ashar; Ahmed, Husnain; Park, Jinsoo; Jung, Jin Ho; Park, Kwangseok; Sung, Hyung Jin

    2018-02-01

    Surface acoustic waves (SAWs) generated in a piezoelectric substrate couple with a liquid according to Snell's law such that a compressional acoustic wave propagates obliquely at a Rayleigh angle ( θ t) inside the microchannel to form a region devoid of a direct acoustic field, which is termed a microchannel anechoic corner (MAC). In the present study, we used microchannels with various heights and widths to characterize the width of the MAC region formed by a single travelling SAW. The attenuation of high-frequency SAWs produced a strong acoustic streaming flow that moved the particles in and out of the MAC region, whereas reflections of the acoustic waves within the microchannel resulted in standing acoustic waves that trapped particles at acoustic pressure nodes located within or outside of the MAC region. A range of actuation frequencies and particle diameters were used to investigate the effects of the acoustic streaming flow and the direct acoustic radiation forces by the travelling as well as standing waves on the particle motion with respect to the MAC region. The width of the MAC ( w c), measured experimentally by tracing the particles, increased with the height of the microchannel ( h m) according to a simple trigonometric equation w c = h m × tan ( θ t ).

  12. Response of the human tympanic membrane to transient acoustic and mechanical stimuli: Preliminary results

    Science.gov (United States)

    Razavi, Payam; Ravicz, Michael E.; Dobrev, Ivo; Cheng, Jeffrey Tao; Furlong, Cosme; Rosowski, John J.

    2016-01-01

    The response of the tympanic membrane (TM) to transient environmental sounds and the contributions of different parts of the TM to middle-ear sound transmission were investigated by measuring the TM response to global transients (acoustic clicks) and to local transients (mechanical impulses) applied to the umbo and various locations on the TM. A lightly-fixed human temporal bone was prepared by removing the ear canal, inner ear, and stapes, leaving the incus, malleus, and TM intact. Motion of nearly the entire TM was measured by a digital holography system with a high speed camera at a rate of 42 000 frames per second, giving a temporal resolution of <24 μs for the duration of the TM response. The entire TM responded nearly instantaneously to acoustic transient stimuli, though the peak displacement and decay time constant varied with location. With local mechanical transients, the TM responded first locally at the site of stimulation, and the response spread approximately symmetrically and circumferentially around the umbo and manubrium. Acoustic and mechanical transients provide distinct and complementary stimuli for the study of TM response. Spatial variations in decay and rate of spread of response imply local variations in TM stiffness, mass, and damping. PMID:26880098

  13. On a computational study for investigating acoustic streaming and heating during focused ultrasound ablation of liver tumor

    International Nuclear Information System (INIS)

    Solovchuk, Maxim A.; Sheu, Tony W.H.; Thiriet, Marc; Lin, Win-Li

    2013-01-01

    The influences of blood vessels and focused location on temperature distribution during high-intensity focused ultrasound (HIFU) ablation of liver tumors are studied numerically. A three-dimensional acoustics-thermal-fluid coupling model is employed to compute the temperature field in the hepatic cancerous region. The model construction is based on the linear Westervelt and bioheat equations as well as the nonlinear Navier–Stokes equations for the liver parenchyma and blood vessels. The effect of acoustic streaming is also taken into account in the present HIFU simulation study. Different blood vessel diameters and focal point locations were investigated. We found from this three-dimensional numerical study that in large blood vessels both the convective cooling and acoustic streaming can considerably change the temperature field and the thermal lesion near blood vessels. If the blood vessel is located within the beam width, both acoustic streaming and blood flow cooling effects should be addressed. The temperature rise on the blood vessel wall generated by a 1.0 MHz focused ultrasound transducer with the focal intensity 327 W/cm 2 was 54% lower when acoustic streaming effect was taken into account. Subject to the applied acoustic power the streaming velocity in a 3 mm blood vessel is 12 cm/s. Thirty percent of the necrosed volume can be reduced, when taking into account the acoustic streaming effect. -- Highlights: • 3D three-field coupling physical model for focused ultrasound tumor ablation is presented. • Acoustic streaming and blood flow cooling effects on ultrasound heating are investigated. • Acoustic streaming can considerably affect the temperature distribution. • The lesion can be reduced by 30% due to the acoustic streaming effect. • Temperature on the blood vessel wall is reduced by 54% due to the acoustic streaming effect

  14. THE AUTOMATIC LIGHTENING LOCATION SYSTEM AND ITS ...

    African Journals Online (AJOL)

    ES Obe

    systems. The implications of the lightening location system for the Nigerian electric power system are also highlighted. ... system (the LLP type) is currently operating in may countries .... (iii) Real time lightning maps will aid service restoration.

  15. Acoustic Quality Levels of Mosques in Batu Pahat

    Science.gov (United States)

    Azizah Adnan, Nor; Nafida Raja Shahminan, Raja; Khair Ibrahim, Fawazul; Tami, Hannifah; Yusuff, M. Rizal M.; Murniwaty Samsudin, Emedya; Ismail, Isham

    2018-04-01

    Every Friday, Muslims has been required to perform a special prayer known as the Friday prayers which involve the delivery of a brief lecture (Khutbah). Speech intelligibility in oral communications presented by the preacher affected all the congregation and determined the level of acoustic quality in the interior of the mosque. Therefore, this study intended to assess the level of acoustic quality of three public mosques in Batu Pahat. Good acoustic quality is essential in contributing towards appreciation in prayers and increasing khusyu’ during the worship, which is closely related to the speech intelligibility corresponding to the actual function of the mosque according to Islam. Acoustic parameters measured includes noise criteria (NC), reverberation time (RT) and speech transmission index (STI), and was performed using the sound level meter and sound measurement instruments. This test is carried out through the physical observation with the consideration of space and volume design as a factor affecting acoustic parameters. Results from all 3 mosques as the showed that the acoustic quality level inside these buildings are slightly poor which is at below 0.45 coefficients based on the standard. Among the factors that influencing the low acoustical quality are location, building materials, installation of sound absorption material and the number of occupants inside the mosque. As conclusion, the acoustic quality level of a mosque is highly depends on physical factors of the mosque such as the architectural design and space volume besides other factors as been identified by this study.

  16. Portable vibro-acoustic testing system for in situ microstructure characterization and metrology

    Science.gov (United States)

    Smith, James A.; Nichol, Corrie I.; Zuck, Larry D.; Fatemi, Mostafa

    2018-04-01

    There is a need in research reactors like the one at INL to inspect irradiated materials and structures. The goal of this work is to develop a portable scanning infrastructure for a material characterization technique called vibro-acoustography (VA) that has been developed by the Idaho National laboratory for nuclear applications to characterize fuel, cladding materials, and structures. The proposed VA technology is based on ultrasound and acoustic waves; however, it provides information beyond what is available from the traditional ultrasound techniques and can expand the knowledge on nuclear material characterization and microstructure evolution. This paper will report on the development of a portable scanning system that will be set up to characterize materials and components in open water reactors and canals in situ. We will show some initial laboratory results of images generated by vibro-acoustics of surrogate fuel plates and graphite structures and discuss the design of the portable system.

  17. Resonant acoustic transducer system for a well drilling string

    Science.gov (United States)

    Nardi, Anthony P.

    1981-01-01

    For use in transmitting acoustic waves propated along a well drilling string, a piezoelectric transducer is provided operating in the relatively low loss acoustic propagation range of the well drilling string. The efficiently coupled transmitting transducer incorporates a mass-spring-piezoelectric transmitter combination permitting a resonant operation in the desired low frequency range.

  18. Use of perforated acoustic panels as supply air diffusers in diffuse ceiling ventilation systems

    DEFF Research Database (Denmark)

    Iqbal, Ahsan; Kazemi, Seyed Hossein; Ardkapan, Siamak Rahimi

    Ventilation is needed for diluting and removing the contaminants, odour and excess heat from the building interior. It is important that the inhabitants perceive the ventilated spaces as comfortable. Therefore, the supply air should reach all parts of the occupied zones. Troldtekt has been...... manufacturing perforated acoustic panels for the last 13 years. The panels can be used not only in applications related to acoustics but also as low pressure drop supply air diffusers, particularly in diffuse ceiling ventilation systems. The present study verifies on a theoretically level the performance...

  19. Use of acoustic vortices in acoustic levitation

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller

    2009-01-01

    Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions......, counterbalancing their weight, and ii) acoustic vortices, spinning sound fields that can impinge angular momentum and cause rotation of objects. In this contribution, both force-creating sound fields are studied by means of numerical simulations. The Boundary Element Method is employed to this end. The simulation...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without...

  20. Acoustic engineering and technology '90

    International Nuclear Information System (INIS)

    1990-01-01

    Acoustic monitoring, testing and diagnosis in machines, production processes and products enhance the uptimes and profitability of machinery and plants. 18 papers discuss the current state of the art of acoustic monitoring systems including integrated factory planning as well as industrial health, and noise protection. (DG) [de

  1. Aero-acoustics noise assessment for Wind-Lens turbine

    International Nuclear Information System (INIS)

    Hashem, I.; Mohamed, M.H.; Hafiz, A.A.

    2017-01-01

    This paper introduces an aero-acoustic computational study that investigates the noise caused by one of the most promising wind energy conversion concepts, namely the 'Wind-Lens' technology. The hybrid method - where the flow field and acoustic field are solved separately, was deemed to be an appropriate tool to compute this study. The need to investigate this phenomenon increased gradually, since the feasibility of utilizing Wind-Lens turbine within densely populated cities and urban areas depends largely on their noise generation. Ffowcs Williams-Hawkings (FW-H) equation and its integral solution are used to predict the noise radiating to the farfield. CFD Simulations of transient three-dimensional flow field using (URANS) unsteady Reynolds-averaged Navier-Stokes equations are computed to acquire the acoustic sources location and sound intensity. Then, the noise propagates from the before-mentioned sources to pre-defined virtual microphones positioned in different locations. ANSYS-FLUENT is used to calculate the flow field on and around such turbines which is required for the FW-H code. Some effective parameters are investigated such as Wind-Lens shape, brim height and tip speed ratio. Comparison of the noise emitted from the bare wind turbine and different types of Wind-Lens turbine reveals that, the Wind-Lens generates higher noise intensity. - Highlights: • Aero-acoustic noise generated by wind turbines are one of the major challenges. • Noise from wind turbine equipped with a brimmed diffuser is investigated. • A computational aero-acoustic study using the hybrid method is introduced. • Effective parameters are studied such Wind-Lens shape, brim height and speed ratio. • The optimal shape has a moderate power coefficient and the less noise generation.

  2. Acoustic Purcell Effect for Enhanced Emission

    KAUST Repository

    Landi, Maryam

    2018-03-13

    We observe that our experimentally measured emission power enhancement of a speaker inside a previously proposed metacavity agrees with our numerically calculated enhancement of the density of states (DOS) of the source-cavity system. We interpret the agreement by formulating a relation between the emitted sound power and the acoustic DOS. The formulation is an analog to Fermi’s golden rule in quantum emission. The formulation complements the radiation impedance theory in traditional acoustics for describing sound emission. Our study bridges the gap between acoustic DOS and the acoustic Purcell effect for sound emission enhancement.

  3. Acoustic Purcell Effect for Enhanced Emission

    KAUST Repository

    Landi, Maryam; Zhao, Jiajun; Prather, Wayne E.; Wu, Ying; Zhang, Likun

    2018-01-01

    We observe that our experimentally measured emission power enhancement of a speaker inside a previously proposed metacavity agrees with our numerically calculated enhancement of the density of states (DOS) of the source-cavity system. We interpret the agreement by formulating a relation between the emitted sound power and the acoustic DOS. The formulation is an analog to Fermi’s golden rule in quantum emission. The formulation complements the radiation impedance theory in traditional acoustics for describing sound emission. Our study bridges the gap between acoustic DOS and the acoustic Purcell effect for sound emission enhancement.

  4. Contactless ultrasonic energy transfer for wireless systems: acoustic-piezoelectric structure interaction modeling and performance enhancement

    International Nuclear Information System (INIS)

    Shahab, S; Erturk, A

    2014-01-01

    There are several applications of wireless electronic components with little or no ambient energy available to harvest, yet wireless battery charging for such systems is still of great interest. Example applications range from biomedical implants to sensors located in hazardous environments. Energy transfer based on the propagation of acoustic waves at ultrasonic frequencies is a recently explored alternative that offers increased transmitter-receiver distance, reduced loss and the elimination of electromagnetic fields. As this research area receives growing attention, there is an increased need for fully coupled model development to quantify the energy transfer characteristics, with a focus on the transmitter, receiver, medium, geometric and material parameters. We present multiphysics modeling and case studies of the contactless ultrasonic energy transfer for wireless electronic components submerged in fluid. The source is a pulsating sphere, and the receiver is a piezoelectric bar operating in the 33-mode of piezoelectricity with a fundamental resonance frequency above the audible frequency range. The goal is to quantify the electrical power delivered to the load (connected to the receiver) in terms of the source strength. Both the analytical and finite element models have been developed for the resulting acoustic-piezoelectric structure interaction problem. Resistive and resistive–inductive electrical loading cases are presented, and optimality conditions are discussed. Broadband power transfer is achieved by optimal resistive-reactive load tuning for performance enhancement and frequency-wise robustness. Significant enhancement of the power output is reported due to the use of a hard piezoelectric receiver (PZT-8) instead of a soft counterpart (PZT-5H) as a result of reduced material damping. The analytical multiphysics modeling approach given in this work can be used to predict and optimize the coupled system dynamics with very good accuracy and

  5. Multipoint dynamically reconfigure adaptive distributed fiber optic acoustic emission sensor (FAESense) system for condition based maintenance

    Science.gov (United States)

    Mendoza, Edgar; Prohaska, John; Kempen, Connie; Esterkin, Yan; Sun, Sunjian; Krishnaswamy, Sridhar

    2010-09-01

    This paper describes preliminary results obtained under a Navy SBIR contract by Redondo Optics Inc. (ROI), in collaboration with Northwestern University towards the development and demonstration of a next generation, stand-alone and fully integrated, dynamically reconfigurable, adaptive fiber optic acoustic emission sensor (FAESense™) system for the in-situ unattended detection and localization of shock events, impact damage, cracks, voids, and delaminations in new and aging critical infrastructures found in ships, submarines, aircraft, and in next generation weapon systems. ROI's FAESense™ system is based on the integration of proven state-of-the-art technologies: 1) distributed array of in-line fiber Bragg gratings (FBGs) sensors sensitive to strain, vibration, and acoustic emissions, 2) adaptive spectral demodulation of FBG sensor dynamic signals using two-wave mixing interferometry on photorefractive semiconductors, and 3) integration of all the sensor system passive and active optoelectronic components within a 0.5-cm x 1-cm photonic integrated circuit microchip. The adaptive TWM demodulation methodology allows the measurement of dynamic high frequnency acoustic emission events, while compensating for passive quasi-static strain and temperature drifts. It features a compact, low power, environmentally robust 1-inch x 1-inch x 4-inch small form factor (SFF) package with no moving parts. The FAESense™ interrogation system is microprocessor-controlled using high data rate signal processing electronics for the FBG sensors calibration, temperature compensation and the detection and analysis of acoustic emission signals. Its miniaturized package, low power operation, state-of-the-art data communications, and low cost makes it a very attractive solution for a large number of applications in naval and maritime industries, aerospace, civil structures, the oil and chemical industry, and for homeland security applications.

  6. Extraordinary acoustic transmission through annuluses in air and its applications in acoustic beam splitter and concentrator

    International Nuclear Information System (INIS)

    Ge, Yong; Liu, Shu-sen; Yuan, Shou-qi; Xia, Jian-ping; Guan, Yi-jun; Sun, Hong-xiang; Zhang, Shu-yi

    2016-01-01

    We report an extraordinary acoustic transmission through two layer annuluses made of metal cylinders in air both numerically and experimentally. The effect arises from the enhancement and reconstruction of the incident source induced by different Mie-resonance modes of the annuluses. The proposed system takes advantages of the consistency in the waveform between the input and output waves, the high amplitude amplification of output waves, and the easy adjustment of structure. More interestingly, we investigate the applications of the extraordinary acoustic transmission in the acoustic beam splitter and acoustic concentrator. Our finding should have an impact on ultrasonic applications.

  7. Fluid dynamics of acoustic and hydrodynamic cavitation in hydraulic power systems

    Science.gov (United States)

    Ferrari, A.

    2017-03-01

    Cavitation is the transition from a liquid to a vapour phase, due to a drop in pressure to the level of the vapour tension of the fluid. Two kinds of cavitation have been reviewed here: acoustic cavitation and hydrodynamic cavitation. As acoustic cavitation in engineering systems is related to the propagation of waves through a region subjected to liquid vaporization, the available expressions of the sound speed are discussed. One of the main effects of hydrodynamic cavitation in the nozzles and orifices of hydraulic power systems is a reduction in flow permeability. Different discharge coefficient formulae are analysed in this paper: the Reynolds number and the cavitation number result to be the key fluid dynamical parameters for liquid and cavitating flows, respectively. The latest advances in the characterization of different cavitation regimes in a nozzle, as the cavitation number reduces, are presented. The physical cause of choked flows is explained, and an analogy between cavitation and supersonic aerodynamic flows is proposed. The main approaches to cavitation modelling in hydraulic power systems are also reviewed: these are divided into homogeneous-mixture and two-phase models. The homogeneous-mixture models are further subdivided into barotropic and baroclinic models. The advantages and disadvantages of an implementation of the complete Rayleigh-Plesset equation are examined.

  8. Acoustic emission

    International Nuclear Information System (INIS)

    Nichols, R.W.

    1976-01-01

    The volume contains six papers which together provide an overall review of the inspection technique known as acoustic emission or stress wave emission. The titles are: a welder's introduction to acoustic emission technology; use of acoustic emission for detection of defects as they arise during fabrication; examples of laboratory application and assessment of acoustic emission in the United Kingdom; (Part I: acoustic emission behaviour of low alloy steels; Part II: fatigue crack assessment from proof testing and continuous monitoring); inspection of selected areas of engineering structures by acoustic emission; Japanese experience in laboratory and practical applications of acoustic emission to welded structures; and ASME acoustic emission code status. (U.K.)

  9. Transmission acoustic microscopy investigation

    Science.gov (United States)

    Maev, Roman; Kolosov, Oleg; Levin, Vadim; Lobkis, Oleg

    The nature of acoustic contrast, i.e. the connection of the amplitude and phase of the output signal of the acoustic microscope with the local values of the acoustic parameters of the sample (density, elasticity, viscosity) is a central problem of acoustic microscopy. A considerable number of studies have been devoted to the formation of the output signal of the reflection scanning acoustic microscope. For the transmission acoustic microscope (TAM) this problem has remained almost unstudied. Experimental investigation of the confocal system of the TAM was carried out on an independently manufactured laboratory mockup of the TAM with the working frequency of the 420 MHz. Acoustic lenses with the radius of curvature of about 500 microns and aperture angle of 45 deg were polished out in the end faces of two cylindrical sound conductors made from Al2O3 single crystals with an axis parallel to the axis C of the crystal (the length of the sound conductor is 20 mm; diameter, 6 mm). At the end faces of the sound conductor, opposite to the lenses, CdS transducers with a diameter of 2 mm were disposed. The electric channel of the TAM provided a possibility for registering the amplitude of the microscope output signal in the case of the dynamic range of the 50 dB.

  10. Simple model of photo acoustic system for greenhouse effect

    OpenAIRE

    Fukuhara, Akiko; Kaneko, Fumitoshi; Ogawa, Naohisa

    2010-01-01

    The green house effect is caused by the gases which absorb infrared ray (IR) emitted by the earth. It is worthwhile if we can adjudicate on which gas causes the greenhouse effect in our class. For this purpose, one of our authors, Kaneko has designed an educational tool for testing greenhouse effect \\cite{Kaneko}. This system (hereafter abbreviated PAS) is constructed based on photo acoustic effect. Without difficulty and high cost, we can build PAS and check the IR absorption of gas. In this...

  11. Contribution of self-motion perception to acoustic target localization.

    Science.gov (United States)

    Pettorossi, V E; Brosch, M; Panichi, R; Botti, F; Grassi, S; Troiani, D

    2005-05-01

    The findings of this study suggest that acoustic spatial perception during head movement is achieved by the vestibular system, which is responsible for the correct dynamic of acoustic target pursuit. The ability to localize sounds in space during whole-body rotation relies on the auditory localization system, which recognizes the position of sound in a head-related frame, and on the sensory systems, namely the vestibular system, which perceive head and body movement. The aim of this study was to analyse the contribution of head motion cues to the spatial representation of acoustic targets in humans. Healthy subjects standing on a rotating platform in the dark were asked to pursue with a laser pointer an acoustic target which was horizontally rotated while the body was kept stationary or maintained stationary while the whole body was rotated. The contribution of head motion to the spatial acoustic representation could be inferred by comparing the gains and phases of the pursuit in the two experimental conditions when the frequency was varied. During acoustic target rotation there was a reduction in the gain and an increase in the phase lag, while during whole-body rotations the gain tended to increase and the phase remained constant. The different contributions of the vestibular and acoustic systems were confirmed by analysing the acoustic pursuit during asymmetric body rotation. In this particular condition, in which self-motion perception gradually diminished, an increasing delay in target pursuit was observed.

  12. [Pärtel Lippus. The acoustic features and perception of the Estonian quantity system] / Stefan Werner

    Index Scriptorium Estoniae

    Werner, Stefan

    2012-01-01

    Arvustus: Pärtel Lippus. The acoustic features and perception of the Estonian quantity system. Tartu : Tartu University Press, 2011. (Dissertationes philologiae estonicae Universitatis Tartuensis ; 29)

  13. Developement of leakage localization technique by using acoustic signal

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y. H.; Jeon, J. H.; Seo, D. H.; Kim, K. W. [KAIST, Daejeon (Korea, Republic of)

    2010-07-15

    The objective of this research is to develop a leakage monitoring system for pipelines or valves in the secondary water system of a nuclear power plant. The system aims to detect the existence of leakage and to estimate the leak location, especially by utilizing the noise generated from the leak. It is safe, precise real-time alert system compared with the previous monitoring methods and tools such as the visual test and the thermal imaging camera. When there exists leakage in the pipeline or valves of nuclear power plant, the noise due to gas flow is radiated through leak region. That is, the secondary water system with leakage generates different noise from the system without leakage. This motivates us to measure and analyze the noise generated from the secondary water system, so as firstly to detect the existence of leakage, and secondly to estimate the leak location by using the noise source identification technique such as beamforming and acoustic holography. Especially the beamforming method models the signal from the noise source to estimate the location of source. Therefore, it is necessary to model the noise due to leakage which is dependent upon parameters. In the process of leak localization, the reflected wave due to interior walls and the measurement noise should be removed for the precise estimation. Therefore, we attempt to characterize the reflected wave and the measurement noise by modeling the interior sound field, thus to remove them and to localize the leak location with high precision

  14. A Small Acoustic Goniometer for General Purpose Research.

    Science.gov (United States)

    Pook, Michael L; Loo, Sin Ming

    2016-04-29

    Understanding acoustic events and monitoring their occurrence is a useful aspect of many research projects. In particular, acoustic goniometry allows researchers to determine the source of an event based solely on the sound it produces. The vast majority of acoustic goniometry research projects used custom hardware targeted to the specific application under test. Unfortunately, due to the wide range of sensing applications, a flexible general purpose hardware/firmware system does not exist for this purpose. This article focuses on the development of such a system which encourages the continued exploration of general purpose hardware/firmware and lowers barriers to research in projects requiring the use of acoustic goniometry. Simulations have been employed to verify system feasibility, and a complete hardware implementation of the acoustic goniometer has been designed and field tested. The results are reported, and suggested areas for improvement and further exploration are discussed.

  15. Inverse acoustic problem of N homogeneous scatterers

    DEFF Research Database (Denmark)

    Berntsen, Svend

    2002-01-01

    The three-dimensional inverse acoustic medium problem of N homogeneous objects with known geometry and location is considered. It is proven that one scattering experiment is sufficient for the unique determination of the complex wavenumbers of the objects. The mapping from the scattered fields...

  16. Parametric study of an acoustic levitation system. [for thermophysical properties determination of nonmetal materials

    Science.gov (United States)

    Oran, W. A.; Berge, L. H.; Parker, H. W.

    1980-01-01

    The performance of an acoustic levitation system designed for the containerless processing of materials and consisting of a St. Clair generator and a reflector arranged in a six-axis configuration, is examined in order to define critical parameters of high-temperature systems and limitations of earth-based devices. The fields and forces along the axis of the system are measured and the forces are plotted versus body volume. It is found that for a range of shapes and sizes the levitation force is roughly proportional to body volume until the characteristic 'diameter' reaches a value of about lambda/2. A significant (i.e., factor of four) enhancement in the levitation force is obtained by curving the faces of the driver and reflector. In addition, the behavior of liquid materials in the acoustic fields is studied, and the radius at which the deformation of a levitated drop occurs is calculated.

  17. A 3D approximate maximum likelihood solver for localization of fish implanted with acoustic transmitters

    Science.gov (United States)

    Li, Xinya; Deng, Z. Daniel; Sun, Yannan; Martinez, Jayson J.; Fu, Tao; McMichael, Geoffrey A.; Carlson, Thomas J.

    2014-11-01

    Better understanding of fish behavior is vital for recovery of many endangered species including salmon. The Juvenile Salmon Acoustic Telemetry System (JSATS) was developed to observe the out-migratory behavior of juvenile salmonids tagged by surgical implantation of acoustic micro-transmitters and to estimate the survival when passing through dams on the Snake and Columbia Rivers. A robust three-dimensional solver was needed to accurately and efficiently estimate the time sequence of locations of fish tagged with JSATS acoustic transmitters, to describe in sufficient detail the information needed to assess the function of dam-passage design alternatives. An approximate maximum likelihood solver was developed using measurements of time difference of arrival from all hydrophones in receiving arrays on which a transmission was detected. Field experiments demonstrated that the developed solver performed significantly better in tracking efficiency and accuracy than other solvers described in the literature.

  18. Translational illusion of acoustic sources by transformation acoustics.

    Science.gov (United States)

    Sun, Fei; Li, Shichao; He, Sailing

    2017-09-01

    An acoustic illusion of creating a translated acoustic source is designed by utilizing transformation acoustics. An acoustic source shifter (ASS) composed of layered acoustic metamaterials is designed to achieve such an illusion. A practical example where the ASS is made with naturally available materials is also given. Numerical simulations verify the performance of the proposed device. The designed ASS may have some applications in, e.g., anti-sonar detection.

  19. Acoustic forcing of a liquid drop

    Science.gov (United States)

    Lyell, M. J.

    1992-01-01

    The development of systems such as acoustic levitation chambers will allow for the positioning and manipulation of material samples (drops) in a microgravity environment. This provides the capability for fundamental studies in droplet dynamics as well as containerless processing work. Such systems use acoustic radiation pressure forces to position or to further manipulate (e.g., oscillate) the sample. The primary objective was to determine the effect of a viscous acoustic field/tangential radiation pressure forcing on drop oscillations. To this end, the viscous acoustic field is determined. Modified (forced) hydrodynamic field equations which result from a consistent perturbation expansion scheme are solved. This is done in the separate cases of an unmodulated and a modulated acoustic field. The effect of the tangential radiation stress on the hydrodynamic field (drop oscillations) is found to manifest as a correction to the velocity field in a sublayer region near the drop/host interface. Moreover, the forcing due to the radiation pressure vector at the interface is modified by inclusion of tangential stresses.

  20. Room acoustic simulation system considered wave motion chacteristic; Hadosei wo koryoshita shitsunai onba simulation system

    Energy Technology Data Exchange (ETDEWEB)

    Tsuboi, M.; Watanabe, M.; Hirano, S. [Obayashi Corp., Osaka (Japan). Technical Research Inst.

    1996-03-20

    A practical calculating method is developed, which includes data of all audible frequencies used as the basic data for visible and audible acoustic evaluation of the sound field for supporting acoustic designing, and can calculate long term impulse responses covering those of reverberation. By the face integration method which performs calculation by dividing the responses from the face elements, at each sound input to the boundary surface, into geometrical wave components and scattered wave components, it is shown that long time impulse response can be calculated with no need for drastic increase in the calculating time. No extreme deterioration of the accuracy is observed even when the face elements are divided roughly, and the method can be applied to response calculation even in a limited time with less divided number of the wave face elements for certain items to be investigated. Sound field is visualized by three dimensional image sound source distribution in which the frequency characteristics of the initial reflected sound are displayed in color, and a series of systems are developed which enable virtual experience of estimated sound field with three dimensional spread by binaural hearing based on OSS (orthostereophonic system). 9 refs., 8 figs.

  1. Virtual reflections in electronic acoustic architecture

    Science.gov (United States)

    van Munster, Bjorn

    2005-09-01

    In the era of the ancient Greeks and Byzantines, the first attempts for increasing reverberation time are noted. In the 1950s, the Ambiophonic system accomplished this by means of an electronic device, for the first time. The early systems only increased the reverberation time by delaying the picked-up reverberation. With the introduction of multichannel feedback-based systems, the reverberation level also could be increased. Later, it was understood that it was important to also fill in the missing reflections, address reflection density, frequency dependence, etc. This resulted in the development of the SIAP concept. Current DSP technology led to the development of a processor whereby density, length, level, and the frequency content can be controlled for different areas in the same room or different rooms, leading to the concept of the acoustic server. electronic acoustic architecture has become the current state-of-the-art approach for solving acoustic deficiencies in, among others, rehearsal rooms, theaters, churches, and multipurpose venues. Incorporation of complementary passive acoustic solutions provides an optimum solution for all room problems. This paper discusses the utilization of virtual reflections in the new approach of electronic acoustic architecture for different environments. Measurements performed in the Sejong Performing Arts Centre, Seoul, South Korea, show the power of this approach.

  2. Horizontal cloaking and vertical reflection by transformation acoustics

    Directory of Open Access Journals (Sweden)

    Min Kyung Lee

    2013-05-01

    Full Text Available This investigation shows that if an acoustic metamaterial bounded by an external rectangle and an internal circular cavity is properly engineered by a set of transformation equations that satisfy certain requirements, it can virtually cloak an object against incoming acoustic waves in one direction and make an incoming wave along the orthogonal direction reflected by an object located inside its inner cavity. The specific transformation equations realizing the metamaterial are suggested and an analysis is carried out to investigate the wave phenomena taking place along the cavity boundary.

  3. Architecture for multi-technology real-time location systems.

    Science.gov (United States)

    Rodas, Javier; Barral, Valentín; Escudero, Carlos J

    2013-02-07

    The rising popularity of location-based services has prompted considerable research in the field of indoor location systems. Since there is no single technology to support these systems, it is necessary to consider the fusion of the information coming from heterogeneous sensors. This paper presents a software architecture designed for a hybrid location system where we can merge information from multiple sensor technologies. The architecture was designed to be used by different kinds of actors independently and with mutual transparency: hardware administrators, algorithm developers and user applications. The paper presents the architecture design, work-flow, case study examples and some results to show how different technologies can be exploited to obtain a good estimation of a target position.

  4. Energy Harvesting Hybrid Acoustic-Optical Underwater Wireless Sensor Networks Localization

    Directory of Open Access Journals (Sweden)

    Nasir Saeed

    2017-12-01

    Full Text Available Underwater wireless technologies demand to transmit at higher data rate for ocean exploration. Currently, large coverage is achieved by acoustic sensor networks with low data rate, high cost, high latency, high power consumption, and negative impact on marine mammals. Meanwhile, optical communication for underwater networks has the advantage of the higher data rate albeit for limited communication distances. Moreover, energy consumption is another major problem for underwater sensor networks, due to limited battery power and difficulty in replacing or recharging the battery of a sensor node. The ultimate solution to this problem is to add energy harvesting capability to the acoustic-optical sensor nodes. Localization of underwater sensor networks is of utmost importance because the data collected from underwater sensor nodes is useful only if the location of the nodes is known. Therefore, a novel localization technique for energy harvesting hybrid acoustic-optical underwater wireless sensor networks (AO-UWSNs is proposed. AO-UWSN employs optical communication for higher data rate at a short transmission distance and employs acoustic communication for low data rate and long transmission distance. A hybrid received signal strength (RSS based localization technique is proposed to localize the nodes in AO-UWSNs. The proposed technique combines the noisy RSS based measurements from acoustic communication and optical communication and estimates the final locations of acoustic-optical sensor nodes. A weighted multiple observations paradigm is proposed for hybrid estimated distances to suppress the noisy observations and give more importance to the accurate observations. Furthermore, the closed form solution for Cramer-Rao lower bound (CRLB is derived for localization accuracy of the proposed technique.

  5. Energy Harvesting Hybrid Acoustic-Optical Underwater Wireless Sensor Networks Localization.

    Science.gov (United States)

    Saeed, Nasir; Celik, Abdulkadir; Al-Naffouri, Tareq Y; Alouini, Mohamed-Slim

    2017-12-26

    Underwater wireless technologies demand to transmit at higher data rate for ocean exploration. Currently, large coverage is achieved by acoustic sensor networks with low data rate, high cost, high latency, high power consumption, and negative impact on marine mammals. Meanwhile, optical communication for underwater networks has the advantage of the higher data rate albeit for limited communication distances. Moreover, energy consumption is another major problem for underwater sensor networks, due to limited battery power and difficulty in replacing or recharging the battery of a sensor node. The ultimate solution to this problem is to add energy harvesting capability to the acoustic-optical sensor nodes. Localization of underwater sensor networks is of utmost importance because the data collected from underwater sensor nodes is useful only if the location of the nodes is known. Therefore, a novel localization technique for energy harvesting hybrid acoustic-optical underwater wireless sensor networks (AO-UWSNs) is proposed. AO-UWSN employs optical communication for higher data rate at a short transmission distance and employs acoustic communication for low data rate and long transmission distance. A hybrid received signal strength (RSS) based localization technique is proposed to localize the nodes in AO-UWSNs. The proposed technique combines the noisy RSS based measurements from acoustic communication and optical communication and estimates the final locations of acoustic-optical sensor nodes. A weighted multiple observations paradigm is proposed for hybrid estimated distances to suppress the noisy observations and give more importance to the accurate observations. Furthermore, the closed form solution for Cramer-Rao lower bound (CRLB) is derived for localization accuracy of the proposed technique.

  6. Energy Harvesting Hybrid Acoustic-Optical Underwater Wireless Sensor Networks Localization

    KAUST Repository

    Saeed, Nasir; Celik, Abdulkadir; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2017-01-01

    Underwater wireless technologies demand to transmit at higher data rate for ocean exploration. Currently, large coverage is achieved by acoustic sensor networks with low data rate, high cost, high latency, high power consumption, and negative impact on marine mammals. Meanwhile, optical communication for underwater networks has the advantage of the higher data rate albeit for limited communication distances. Moreover, energy consumption is another major problem for underwater sensor networks, due to limited battery power and difficulty in replacing or recharging the battery of a sensor node. The ultimate solution to this problem is to add energy harvesting capability to the acoustic-optical sensor nodes. Localization of underwater sensor networks is of utmost importance because the data collected from underwater sensor nodes is useful only if the location of the nodes is known. Therefore, a novel localization technique for energy harvesting hybrid acoustic-optical underwater wireless sensor networks (AO-UWSNs) is proposed. AO-UWSN employs optical communication for higher data rate at a short transmission distance and employs acoustic communication for low data rate and long transmission distance. A hybrid received signal strength (RSS) based localization technique is proposed to localize the nodes in AO-UWSNs. The proposed technique combines the noisy RSS based measurements from acoustic communication and optical communication and estimates the final locations of acoustic-optical sensor nodes. A weighted multiple observations paradigm is proposed for hybrid estimated distances to suppress the noisy observations and give more importance to the accurate observations. Furthermore, the closed form solution for Cramer-Rao lower bound (CRLB) is derived for localization accuracy of the proposed technique.

  7. Energy Harvesting Hybrid Acoustic-Optical Underwater Wireless Sensor Networks Localization

    KAUST Repository

    Saeed, Nasir

    2017-12-26

    Underwater wireless technologies demand to transmit at higher data rate for ocean exploration. Currently, large coverage is achieved by acoustic sensor networks with low data rate, high cost, high latency, high power consumption, and negative impact on marine mammals. Meanwhile, optical communication for underwater networks has the advantage of the higher data rate albeit for limited communication distances. Moreover, energy consumption is another major problem for underwater sensor networks, due to limited battery power and difficulty in replacing or recharging the battery of a sensor node. The ultimate solution to this problem is to add energy harvesting capability to the acoustic-optical sensor nodes. Localization of underwater sensor networks is of utmost importance because the data collected from underwater sensor nodes is useful only if the location of the nodes is known. Therefore, a novel localization technique for energy harvesting hybrid acoustic-optical underwater wireless sensor networks (AO-UWSNs) is proposed. AO-UWSN employs optical communication for higher data rate at a short transmission distance and employs acoustic communication for low data rate and long transmission distance. A hybrid received signal strength (RSS) based localization technique is proposed to localize the nodes in AO-UWSNs. The proposed technique combines the noisy RSS based measurements from acoustic communication and optical communication and estimates the final locations of acoustic-optical sensor nodes. A weighted multiple observations paradigm is proposed for hybrid estimated distances to suppress the noisy observations and give more importance to the accurate observations. Furthermore, the closed form solution for Cramer-Rao lower bound (CRLB) is derived for localization accuracy of the proposed technique.

  8. Software-based acoustical measurements

    CERN Document Server

    Miyara, Federico

    2017-01-01

    This textbook provides a detailed introduction to the use of software in combination with simple and economical hardware (a sound level meter with calibrated AC output and a digital recording system) to obtain sophisticated measurements usually requiring expensive equipment. It emphasizes the use of free, open source, and multiplatform software. Many commercial acoustical measurement systems use software algorithms as an integral component; however the methods are not disclosed. This book enables the reader to develop useful algorithms and provides insight into the use of digital audio editing tools to document features in the signal. Topics covered include acoustical measurement principles, in-depth critical study of uncertainty applied to acoustical measurements, digital signal processing from the basics, and metrologically-oriented spectral and statistical analysis of signals. The student will gain a deep understanding of the use of software for measurement purposes; the ability to implement software-based...

  9. Acoustic communication in the Greater Sage-Grouse (Centrocercus urophasianus) an examination into vocal sacs, sound propagation, and signal directionality

    Science.gov (United States)

    Dantzker, Marc Steven

    The thesis is an inquiry into the acoustic communication of a very unusual avian species, the Greater Sage-Grouse, Centrocercus urophasianus. One of the most outstanding features of this animal's dynamic mating display is its use of paired air sacs that emerge explosively from an esophageal pouch. My first line of inquiry into this system is a review of the form and function of similar vocal apparatuses, collectively called vocal sacs, in birds. Next, with a combination of mathematical models and field measurements, My collaborator and I investigate the acoustic environment where the Greater Sage-Grouse display. The complexities of this acoustic environment are relevant both to the birds and to the subsequent examinations of the display's properties. Finally, my collaborators and I examine a cryptic component of the acoustic display --- directionality --- which we measured simultaneously from multiple locations around free moving grouse on their mating grounds.

  10. Relationships between acoustic emissions and microstructures

    International Nuclear Information System (INIS)

    Rao, G.V.; Gopal, R.

    1979-01-01

    Results of a systematic study of 'microstructure-deformation-acoustic emission' relationships on two widely used pressure retaining component materials, namely A533-B nuclear pressure vessel steel and a 7075 aluminum alloy, are presented. The study consists of conducting acoustic monitored tensile tests on a variety of quenched and aged microstructures in the two alloy systems and extensive microstructural characterization of test specimens by light optic and electron microscopy techniques. The results suggest a consistent relationship between acoustic emissions and microdeformation mechanisms. The role of specific microstructural constituents in generating acoustic emissions in the two alloys is discussed. (author)

  11. Scale Model Thruster Acoustic Measurement Results

    Science.gov (United States)

    Vargas, Magda; Kenny, R. Jeremy

    2013-01-01

    The Space Launch System (SLS) Scale Model Acoustic Test (SMAT) is a 5% scale representation of the SLS vehicle, mobile launcher, tower, and launch pad trench. The SLS launch propulsion system will be comprised of the Rocket Assisted Take-Off (RATO) motors representing the solid boosters and 4 Gas Hydrogen (GH2) thrusters representing the core engines. The GH2 thrusters were tested in a horizontal configuration in order to characterize their performance. In Phase 1, a single thruster was fired to determine the engine performance parameters necessary for scaling a single engine. A cluster configuration, consisting of the 4 thrusters, was tested in Phase 2 to integrate the system and determine their combined performance. Acoustic and overpressure data was collected during both test phases in order to characterize the system's acoustic performance. The results from the single thruster and 4- thuster system are discussed and compared.

  12. Acoustic emission from fuel pellets in a simulated reactor environment

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Kennedy, C.R.; Reimann, K.J.

    1977-01-01

    Thermal-shock damage of nuclear reactor fuel pellets in a simulated reactor environment has been correlated with acoustic-emission data obtained from sensors placed on extensions of the electrical feedthroughs. Ringdown counts, rms output data, and event-location data has been acquired for experiments carried out with single pellets as well as multiple pellet stacks. These tests have shown that acoustic-emission monitoring can provide information indicating the onset and the extent of cracking

  13. Impact of flow induced vibration acoustic loads on the design of the Laguna Verde Unit 2 steam dryer

    International Nuclear Information System (INIS)

    Forsyth, D. R.; Wellstein, L. F.; Theuret, R. C.; Han, Y.; Rajakumar, C.; Amador C, C.; Sosa F, W.

    2015-09-01

    Industry experience with Boiling Water Reactors (BWRs) has shown that increasing the steam flow through the main steam lines (MSLs) to implement an extended power up rate (EPU) may lead to amplified acoustic loads on the steam dryer, which may negatively affect the structural integrity of the component. The source of these acoustic loads has been found to be acoustic resonance of the side branches on the MSLs, specifically, coupling of the vortex shedding frequency and natural acoustic frequency of safety relief valves (SRVs). The resonance that results from this coupling can contribute significant acoustic energy into the MSL system, which may propagate upstream into the reactor pressure vessel steam dome and drive structural vibration of steam dryer components. This can lead to high-cycle fatigue issues. Lock-in between the vortex shedding frequency and SRV natural frequency, as well as the ability for acoustic energy to propagate into the MSL system, are a function of many things, including the plant operating conditions, geometry of the MSL/SRV junction, and placement of SRVs with respect to each other on the MSLs. Comision Federal de Electricidad and Westinghouse designed, fabricated, and installed acoustic side branches (ASBs) on the MSLs which effectively act in the system as an energy absorber, where the acoustic standing wave generated in the side-branch is absorbed and dissipated inside the ASB. These ASBs have been very successful in reducing the amount of acoustic energy which propagates into the steam dome. In addition, modifications to the Laguna Verde Nuclear Power Plant Unit 2 steam dryer have been completed to reduce the stress levels in critical locations in the dryer. The objective of this paper is to describe the acoustic side branch concept and the design iterative processes that were undertaken at Laguna Verde Unit 2 to achieve a steam dryer design that meets the guidelines of the American Society of Mechanical Engineers, Boiler and Pressure

  14. Impact of flow induced vibration acoustic loads on the design of the Laguna Verde Unit 2 steam dryer

    Energy Technology Data Exchange (ETDEWEB)

    Forsyth, D. R.; Wellstein, L. F.; Theuret, R. C.; Han, Y.; Rajakumar, C. [Westinghouse Electric Company LLC, Cranberry Township, PA 16066 (United States); Amador C, C.; Sosa F, W., E-mail: forsytdr@westinghouse.com [Comision Federal de Electricidad, Central Nucleoelectrica Laguna Verde, Km 42.5 Carretera Cardel-Nautla, 91680 Alto Lucero, Veracruz (Mexico)

    2015-09-15

    Industry experience with Boiling Water Reactors (BWRs) has shown that increasing the steam flow through the main steam lines (MSLs) to implement an extended power up rate (EPU) may lead to amplified acoustic loads on the steam dryer, which may negatively affect the structural integrity of the component. The source of these acoustic loads has been found to be acoustic resonance of the side branches on the MSLs, specifically, coupling of the vortex shedding frequency and natural acoustic frequency of safety relief valves (SRVs). The resonance that results from this coupling can contribute significant acoustic energy into the MSL system, which may propagate upstream into the reactor pressure vessel steam dome and drive structural vibration of steam dryer components. This can lead to high-cycle fatigue issues. Lock-in between the vortex shedding frequency and SRV natural frequency, as well as the ability for acoustic energy to propagate into the MSL system, are a function of many things, including the plant operating conditions, geometry of the MSL/SRV junction, and placement of SRVs with respect to each other on the MSLs. Comision Federal de Electricidad and Westinghouse designed, fabricated, and installed acoustic side branches (ASBs) on the MSLs which effectively act in the system as an energy absorber, where the acoustic standing wave generated in the side-branch is absorbed and dissipated inside the ASB. These ASBs have been very successful in reducing the amount of acoustic energy which propagates into the steam dome. In addition, modifications to the Laguna Verde Nuclear Power Plant Unit 2 steam dryer have been completed to reduce the stress levels in critical locations in the dryer. The objective of this paper is to describe the acoustic side branch concept and the design iterative processes that were undertaken at Laguna Verde Unit 2 to achieve a steam dryer design that meets the guidelines of the American Society of Mechanical Engineers, Boiler and Pressure

  15. Acoustic effects of single electrostatic discharges

    International Nuclear Information System (INIS)

    Orzech, Łukasz

    2015-01-01

    Electric discharges, depending on their character, can emit different types of energy, resulting in different effects. Single electrostatic discharges besides generation of electromagnetic pulses are also the source of N acoustic waves. Their specified parameters depending on amount of discharging charge enable determination of value of released charge in a function of acoustic descriptor (e.g. acoustic pressure). Presented approach is the basics of acoustic method for measurement of single electrostatic discharges, enabling direct and contactless measurement of value of charge released during ESD. Method for measurement of acoustic effect of impact of a single electrostatic discharge on the environment in a form of pressure shock wave and examples of acoustic descriptors in a form of equation Q=f(p a ) are described. The properties of measuring system as well as the results of regression static analyses used to determine the described relationships are analysed in details. (paper)

  16. Pico-litre Sample Introduction and Acoustic Levitation Systems for Time Resolved Protein Crystallography Experiments at XFELS

    Directory of Open Access Journals (Sweden)

    Peter Docker

    2017-07-01

    Full Text Available The system described in this work is a variant from traditional acoustic levitation first described by, Marzo et al. It uses multiple transducers eliminating the requirement for a mirror surface, allowing for an open geometry as the sound from multiple transducers combines to generate the acoustic trap which is configured to catch pico litres of crystal slurries. These acoustic traps also have the significant benefit of eliminating potential beam attenuation due to support structures or microfluidic devices. Additionally they meet the need to eliminate sample environments when experiments are carried out using an X-ray Free Electron Lasers (XFEL such as the Linac Coherent Light Source (LCLS as any sample environment would not survive the exposure to the X-Ray beam. XFELs generate Light a billion times brighter than the sun. The application for this system will be to examine turn over in Beta lactamase proteins which is responsible for bacteria developing antibiotic resistance and therefore of significant importance to future world health. The system will allow for diffraction data to be collected before and after turnover allowing for a better understanding of the underling processes. The authors first described this work at Nanotech 2017.

  17. Building Acoustics

    Science.gov (United States)

    Cowan, James

    This chapter summarizes and explains key concepts of building acoustics. These issues include the behavior of sound waves in rooms, the most commonly used rating systems for sound and sound control in buildings, the most common noise sources found in buildings, practical noise control methods for these sources, and the specific topic of office acoustics. Common noise issues for multi-dwelling units can be derived from most of the sections of this chapter. Books can be and have been written on each of these topics, so the purpose of this chapter is to summarize this information and provide appropriate resources for further exploration of each topic.

  18. The Development of the Acoustic Design of NASA Glenn Research Center's New Reverberant Acoustic Test Facility

    Science.gov (United States)

    Hughes, William O.; McNelis, Mark E.; Hozman, Aron D.; McNelis, Anne M.

    2011-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC s Plum Brook Station in Sandusky, Ohio. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA s space exploration program. The large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 ft3 in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world s known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada s acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic design and subsequent on-going construction.

  19. Architecture for Multi-Technology Real-Time Location Systems

    Science.gov (United States)

    Rodas, Javier; Barral, Valentín; Escudero, Carlos J.

    2013-01-01

    The rising popularity of location-based services has prompted considerable research in the field of indoor location systems. Since there is no single technology to support these systems, it is necessary to consider the fusion of the information coming from heterogeneous sensors. This paper presents a software architecture designed for a hybrid location system where we can merge information from multiple sensor technologies. The architecture was designed to be used by different kinds of actors independently and with mutual transparency: hardware administrators, algorithm developers and user applications. The paper presents the architecture design, work-flow, case study examples and some results to show how different technologies can be exploited to obtain a good estimation of a target position. PMID:23435050

  20. Evaluation of the sensitivity of electro-acoustic measurements for process monitoring and control of an atmospheric pressure plasma jet system

    Energy Technology Data Exchange (ETDEWEB)

    Law, V J [Dublin City University, National Centre of Plasma Science and Technology, Collins Avenue, Glasnevin, Dublin 9, Dublin (Ireland); O' Neill, F T; Dowling, D P, E-mail: vic.law@dcu.ie [School Mechanical and Materials Engineering, University College Dublin, Belfield, Dublin 4 (Ireland)

    2011-06-15

    The development of non-invasive process diagnostic techniques for the control of atmospheric plasmas is a critical issue for the wider adoption of this technology. This paper evaluates the use of a frequency-domain deconvolution of an electro-acoustic emission as a means to monitor and control the plasma formed using an atmospheric pressure plasma jet (APPJ) system. The air plasma system investigated was formed using a PlasmaTreat(TM) OpenAir applicator. Change was observed in the electro-acoustic signal with changes in substrate type (ceramic, steel, polymer). APPJ nozzle to substrate distance and substrate feature size were monitored. The decoding of the electro-acoustic emission yields three subdatasets that are described by three separate emission mechanisms. The three emissions are associated with the power supply fundamental drive frequency and its harmonics, the APPJ nozzle longitudinal mode acoustic emission and its odd overtones, and the acoustic surface reflection that is produced by the impedance mismatch between the discharge and the surface. Incorporating this knowledge into a LabVIEW program facilitated the continuous deconvolution of the electro-acoustic data. This enabled the use of specific frequency band test limits to control the APPJ treatment process which is sensitive to both plasma processing conditions and substrate type and features.

  1. Acoustic study of fish and invertebrate behavior in a tropical reservoir

    NARCIS (Netherlands)

    Prchalová, M.; Drastík, V.; Kubeka, J.; Sricharoendham, B.; Schiemer, F.; Vijverberg, J.

    2003-01-01

    The fish and invertebrate behavior of the Ubol Ratana Reservoir, Thailand, were monitored using up- and downlooking split beam sonar located at a fixed location. In the same area and period, ichthyoplankton nets and multimesh gillnets were used. The bulk of targets, recorded by acoustics and direct

  2. Transducer placement for robustness to variations in boundary conditions for active structural acoustic control

    Science.gov (United States)

    Sprofera, Joseph D.; Clark, Robert L.; Cabell, Randolph H.; Gibbs, Gary P.

    2005-05-01

    Turbulent boundary layer (TBL) noise is considered a primary contribution to the interior noise present in commercial airliners. There are numerous investigations of interior noise control devoted to aircraft panels; however, practical realization is a potential challenge since physical boundary conditions are uncertain at best. In most prior studies, pinned or clamped boundary conditions were assumed; however, realistic panels likely display a range of boundary conditions between these two limits. Uncertainty in boundary conditions is a challenge for control system designers, both in terms of the compensator implemented and the location of transducers required to achieve the desired control. The impact of model uncertainties, specifically uncertain boundaries, on the selection of transducer locations for structural acoustic control is considered herein. The final goal of this work is the design of an aircraft panel structure that can reduce TBL noise transmission through the use of a completely adaptive, single-input, single-output control system. The feasibility of this goal is demonstrated through the creation of a detailed analytical solution, followed by the implementation of a test model in a transmission loss apparatus. Successfully realizing a control system robust to variations in boundary conditions can lead to the design and implementation of practical adaptive structures that could be used to control the transmission of sound to the interior of aircraft. Results from this research effort indicate it is possible to optimize the design of actuator and sensor location and aperture, minimizing the impact of boundary conditions on the desired structural acoustic control.

  3. Reverberant acoustic energy in auditoria that comprise systems of coupled rooms

    Science.gov (United States)

    Summers, Jason E.

    2003-11-01

    A frequency-dependent model for reverberant energy in coupled rooms is developed and compared with measurements for a 1:10 scale model and for Bass Hall, Ft. Worth, TX. At high frequencies, prior statistical-acoustics models are improved by geometrical-acoustics corrections for decay within sub-rooms and for energy transfer between sub-rooms. Comparisons of computational geometrical acoustics predictions based on beam-axis tracing with scale model measurements indicate errors resulting from tail-correction assuming constant quadratic growth of reflection density. Using ray tracing in the late part corrects this error. For mid-frequencies, the models are modified to account for wave effects at coupling apertures by including power transmission coefficients. Similarly, statical-acoustics models are improved through more accurate estimates of power transmission measurements. Scale model measurements are in accord with the predicted behavior. The edge-diffraction model is adapted to study transmission through apertures. Multiple-order scattering is theoretically and experimentally shown inaccurate due to neglect of slope diffraction. At low frequencies, perturbation models qualitatively explain scale model measurements. Measurements confirm relation of coupling strength to unperturbed pressure distribution on coupling surfaces. Measurements in Bass Hall exhibit effects of the coupled stage house. High frequency predictions of statistical acoustics and geometrical acoustics models and predictions of coupling apertures all agree with measurements.

  4. Development of radio acoustic sounding system (RASS with Gadanki MST radar – first results

    Directory of Open Access Journals (Sweden)

    T. Tsuda

    2008-09-01

    Full Text Available A high-power acoustic exciter was designed and developed for the Gadanki MST Radar to facilitate observations in the Radio Acoustic Sounding System (RASS mode. Sweep range of acoustic signal frequencies was set to 94–125 Hz so as to satisfy Bragg matching condition for temperature range of −90°–40°C between surface and the tropopause (about 17 km. Raytracing of acoustic wave propagation was used to predict the antenna beam directions along which optimum RASS echoes could be obtained. During the RASS observation period of about 18 h on 23–24 July 2006 height profiles of atmospheric virtual temperature were obtained between 1.5 km and 10 km and occasionally up to 14 km. In comparison with the three simultaneous radiosonde launches, RASS derived temperature profiles had the r.m.s. discrepancy of about 1 K, although deviation of the RASS results sometimes appeared when the radial wind velocity was not fully available for the correction of apparent sound speed. This study has successfully demonstrated capability of the RASS application with the Gadanki MST radar, which will be used for continuous monitoring of the temperature profiles in the troposphere and lower stratosphere region in the tropics.

  5. Acoustic source localization : Exploring theory and practice

    NARCIS (Netherlands)

    Wind, Jelmer

    2009-01-01

    Over the past few decades, noise pollution became an important issue in modern society. This has led to an increased effort in the industry to reduce noise. Acoustic source localization methods determine the location and strength of the vibrations which are the cause of sound based onmeasurements of

  6. Design of the Acoustic Signal Receiving Unit of Acoustic Telemetry While Drilling

    Directory of Open Access Journals (Sweden)

    Li Zhigang

    2016-01-01

    Full Text Available Signal receiving unit is one of the core units of the acoustic telemetry system. A new type of acoustic signal receiving unit is designed to solve problems of the existing devices. The unit is a short joint in whole. It not only can receive all the acoustic signals transmitted along the drill string, without losing any signal, but will not bring additional vibration and interference. In addition, the structure of the amplitude transformer is designed, which can amplify the signal amplitude and improve the receiving efficiency. The design of the wireless communication module makes the whole device can be used in normal drilling process when the drill string is rotating. So, it does not interfere with the normal drilling operation.

  7. PASSIVE WIRELESS MULTI-SENSOR TEMPERATURE AND PRESSURE SENSING SYSTEM USING ACOUSTIC WAVE DEVICES, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal describes the development of passive surface acoustic wave (SAW) sensors and multi-sensor systems for NASA application to remote wireless sensing of...

  8. Technical procedures for implementation of acoustics site studies, Deaf Smith County site, Texas: Environmental Field Program: Preliminary draft

    International Nuclear Information System (INIS)

    1987-09-01

    The purpose and scope of the technical procedure for processing data from the tethered meteorological system are covered. Definitions, interfaces, and concurrent data needs are also addressed. This technical procedure describes how to control, organize, verify, and archive tethered meteorological system data. These data will be received at the processing location from the field measurement location and are part of the characterization of the Deaf Smith County Site, Texas for the salt repository program. These measurements will be made in support of the sound propagation study and are a result of environmental data requirements for acoustics. 6 refs., 15 figs., 5 tabs

  9. Novel Fiber-Optic Ring Acoustic Emission Sensor.

    Science.gov (United States)

    Wei, Peng; Han, Xiaole; Xia, Dong; Liu, Taolin; Lang, Hao

    2018-01-13

    Acoustic emission technology has been applied to many fields for many years. However, the conventional piezoelectric acoustic emission sensors cannot be used in extreme environments, such as those with heavy electromagnetic interference, high pressure, or strong corrosion. In this paper, a novel fiber-optic ring acoustic emission sensor is proposed. The sensor exhibits high sensitivity, anti-electromagnetic interference, and corrosion resistance. First, the principle of a novel fiber-optic ring sensor is introduced. Different from piezoelectric and other fiber acoustic emission sensors, this novel sensor includes both a sensing skeleton and a sensing fiber. Second, a heterodyne interferometric demodulating method is presented. In addition, a fiber-optic ring sensor acoustic emission system is built based on this method. Finally, fiber-optic ring acoustic emission experiments are performed. The novel fiber-optic ring sensor is glued onto the surface of an aluminum plate. The 150 kHz standard continuous sinusoidal signals and broken lead signals are successfully detected by the novel fiber-optic ring acoustic emission sensor. In addition, comparison to the piezoelectric acoustic emission sensor is performed, which shows the availability and reliability of the novel fiber-optic ring acoustic emission sensor. In the future, this novel fiber-optic ring acoustic emission sensor will provide a new route to acoustic emission detection in harsh environments.

  10. Microfluidic device for acoustic cell lysis

    Science.gov (United States)

    Branch, Darren W.; Cooley, Erika Jane; Smith, Gennifer Tanabe; James, Conrad D.; McClain, Jaime L.

    2015-08-04

    A microfluidic acoustic-based cell lysing device that can be integrated with on-chip nucleic acid extraction. Using a bulk acoustic wave (BAW) transducer array, acoustic waves can be coupled into microfluidic cartridges resulting in the lysis of cells contained therein by localized acoustic pressure. Cellular materials can then be extracted from the lysed cells. For example, nucleic acids can be extracted from the lysate using silica-based sol-gel filled microchannels, nucleic acid binding magnetic beads, or Nafion-coated electrodes. Integration of cell lysis and nucleic acid extraction on-chip enables a small, portable system that allows for rapid analysis in the field.

  11. Modeling of Structural-Acoustic Interaction Using Coupled FE/BE Method and Control of Interior Acoustic Pressure Using Piezoelectric Actuators

    Science.gov (United States)

    Mei, Chuh; Shi, Yacheng

    1997-01-01

    A coupled finite element (FE) and boundary element (BE) approach is presented to model full coupled structural/acoustic/piezoelectric systems. The dual reciprocity boundary element method is used so that the natural frequencies and mode shapes of the coupled system can be obtained, and to extend this approach to time dependent problems. The boundary element method is applied to interior acoustic domains, and the results are very accurate when compared with limited exact solutions. Structural-acoustic problems are then analyzed with the coupled finite element/boundary element method, where the finite element method models the structural domain and the boundary element method models the acoustic domain. Results for a system consisting of an isotropic panel and a cubic cavity are in good agreement with exact solutions and experiment data. The response of a composite panel backed cavity is then obtained. The results show that the mass and stiffness of piezoelectric layers have to be considered. The coupled finite element and boundary element equations are transformed into modal coordinates, which is more convenient for transient excitation. Several transient problems are solved based on this formulation. Two control designs, a linear quadratic regulator (LQR) and a feedforward controller, are applied to reduce the acoustic pressure inside the cavity based on the equations in modal coordinates. The results indicate that both controllers can reduce the interior acoustic pressure and the plate deflection.

  12. Time-resolved tomography using acoustic emissions in the laboratory, and application to sandstone compaction

    Science.gov (United States)

    Brantut, Nicolas

    2018-02-01

    Acoustic emission and active ultrasonic wave velocity monitoring are often performed during laboratory rock deformation experiments, but are typically processed separately to yield homogenised wave velocity measurements and approximate source locations. Here I present a numerical method and its implementation in a free software to perform a joint inversion of acoustic emission locations together with the three-dimensional, anisotropic P-wave structure of laboratory samples. The data used are the P-wave first arrivals obtained from acoustic emissions and active ultrasonic measurements. The model parameters are the source locations and the P-wave velocity and anisotropy parameter (assuming transverse isotropy) at discrete points in the material. The forward problem is solved using the fast marching method, and the inverse problem is solved by the quasi-Newton method. The algorithms are implemented within an integrated free software package called FaATSO (Fast Marching Acoustic Emission Tomography using Standard Optimisation). The code is employed to study the formation of compaction bands in a porous sandstone. During deformation, a front of acoustic emissions progresses from one end of the sample, associated with the formation of a sequence of horizontal compaction bands. Behind the active front, only sparse acoustic emissions are observed, but the tomography reveals that the P-wave velocity has dropped by up to 15%, with an increase in anisotropy of up to 20%. Compaction bands in sandstones are therefore shown to produce sharp changes in seismic properties. This result highlights the potential of the methodology to image temporal variations of elastic properties in complex geomaterials, including the dramatic, localised changes associated with microcracking and damage generation.

  13. Experimental study of advanced continuous acoustic emission monitoring of BWR components. Final report

    International Nuclear Information System (INIS)

    McElroy, J.W.; Hartman, W.F.

    1980-09-01

    The program consisted of installing, maintaining, and monitoring AE sensors located on primary piping, nozzles, and valves in the BWR system. Analysis of the AE data was correlated to the results of supplementary nondestructive testing techniques used during the in-service inspection, performed at refueling outages. Purpose of the program was to develop the on-line surveillance acoustic emission technique in order to identify areas of possible structural degradation. Result of reducing inspection time was to reduce accumulated radiation exposure to inspecting personnel and to reduce the amount of critical plant outage time by identifying the critical inspection areas during operation. The program demonstrated the capability of acoustic emission instrumentation to endure the nuclear reactor environment. The acoustic emission sensors withstood 12 months of reactor operation at temperatures of 400 0 F and greater in high radiation fields. The preamplifiers, also mounted in the reactor environment, operated for the 12-month period in 100% humidity, 250 0 F conditions. The remaining cable and AE instrumentation were operated in controlled environments

  14. Fundamentals of Acoustics. Psychoacoustics and Hearing. Acoustical Measurements

    Science.gov (United States)

    Begault, Durand R.; Ahumada, Al (Technical Monitor)

    1997-01-01

    These are 3 chapters that will appear in a book titled "Building Acoustical Design", edited by Charles Salter. They are designed to introduce the reader to fundamental concepts of acoustics, particularly as they relate to the built environment. "Fundamentals of Acoustics" reviews basic concepts of sound waveform frequency, pressure, and phase. "Psychoacoustics and Hearing" discusses the human interpretation sound pressure as loudness, particularly as a function of frequency. "Acoustic Measurements" gives a simple overview of the time and frequency weightings for sound pressure measurements that are used in acoustical work.

  15. Communication Acoustics

    DEFF Research Database (Denmark)

    Blauert, Jens

    Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......: acoustics, cognitive science, speech science, and communication technology....

  16. Acoustic sources of opportunity in the marine environment - Applied to source localization and ocean sensing

    Science.gov (United States)

    Verlinden, Christopher M.

    Controlled acoustic sources have typically been used for imaging the ocean. These sources can either be used to locate objects or characterize the ocean environment. The processing involves signal extraction in the presence of ambient noise, with shipping being a major component of the latter. With the advent of the Automatic Identification System (AIS) which provides accurate locations of all large commercial vessels, these major noise sources can be converted from nuisance to beacons or sources of opportunity for the purpose of studying the ocean. The source localization method presented here is similar to traditional matched field processing, but differs in that libraries of data-derived measured replicas are used in place of modeled replicas. In order to account for differing source spectra between library and target vessels, cross-correlation functions are compared instead of comparing acoustic signals directly. The library of measured cross-correlation function replicas is extrapolated using waveguide invariant theory to fill gaps between ship tracks, fully populating the search grid with estimated replicas allowing for continuous tracking. In addition to source localization, two ocean sensing techniques are discussed in this dissertation. The feasibility of estimating ocean sound speed and temperature structure, using ship noise across a drifting volumetric array of hydrophones suspended beneath buoys, in a shallow water marine environment is investigated. Using the attenuation of acoustic energy along eigenray paths to invert for ocean properties such as temperature, salinity, and pH is also explored. In each of these cases, the theory is developed, tested using numerical simulations, and validated with data from acoustic field experiments.

  17. Non-contact test set-up for aeroelasticity in a rotating turbomachine combining a novel acoustic excitation system with tip-timing

    International Nuclear Information System (INIS)

    Freund, O; Seume, J R; Montgomery, M; Mittelbach, M

    2014-01-01

    Due to trends in aero-design, aeroelasticity becomes increasingly important in modern turbomachines. Design requirements of turbomachines lead to the development of high aspect ratio blades and blade integral disc designs (blisks), which are especially prone to complex modes of vibration. Therefore, experimental investigations yielding high quality data are required for improving the understanding of aeroelastic effects in turbomachines. One possibility to achieve high quality data is to excite and measure blade vibrations in turbomachines. The major requirement for blade excitation and blade vibration measurements is to minimize interference with the aeroelastic effects to be investigated. Thus in this paper, a non-contact—and thus low interference—experimental set-up for exciting and measuring blade vibrations is proposed and shown to work. A novel acoustic system excites rotor blade vibrations, which are measured with an optical tip-timing system. By performing measurements in an axial compressor, the potential of the acoustic excitation method for investigating aeroelastic effects is explored. The basic principle of this method is described and proven through the analysis of blade responses at different acoustic excitation frequencies and at different rotational speeds. To verify the accuracy of the tip-timing system, amplitudes measured by tip-timing are compared with strain gage measurements. They are found to agree well. Two approaches to vary the nodal diameter (ND) of the excited vibration mode by controlling the acoustic excitation are presented. By combining the different excitable acoustic modes with a phase-lag control, each ND of the investigated 30 blade rotor can be excited individually. This feature of the present acoustic excitation system is of great benefit to aeroelastic investigations and represents one of the main advantages over other excitation methods proposed in the past. In future studies, the acoustic excitation method will be used

  18. Diagnostic performance of an acoustic-based system for coronary artery disease risk stratification.

    Science.gov (United States)

    Winther, Simon; Nissen, Louise; Schmidt, Samuel Emil; Westra, Jelmer Sybren; Rasmussen, Laust Dupont; Knudsen, Lars Lyhne; Madsen, Lene Helleskov; Kirk Johansen, Jane; Larsen, Bjarke Skogstad; Struijk, Johannes Jan; Frost, Lars; Holm, Niels Ramsing; Christiansen, Evald Høj; Botker, Hans Erik; Bøttcher, Morten

    2017-11-09

    Diagnosing coronary artery disease (CAD) continues to require substantial healthcare resources. Acoustic analysis of transcutaneous heart sounds of cardiac movement and intracoronary turbulence due to obstructive coronary disease could potentially change this. The aim of this study was thus to test the diagnostic accuracy of a new portable acoustic device for detection of CAD. We included 1675 patients consecutively with low to intermediate likelihood of CAD who had been referred for cardiac CT angiography. If significant obstruction was suspected in any coronary segment, patients were referred to invasive angiography and fractional flow reserve (FFR) assessment. Heart sound analysis was performed in all patients. A predefined acoustic CAD-score algorithm was evaluated; subsequently, we developed and validated an updated CAD-score algorithm that included both acoustic features and clinical risk factors. Low risk is indicated by a CAD-score value ≤20. Haemodynamically significant CAD assessed from FFR was present in 145 (10.0%) patients. In the entire cohort, the predefined CAD-score had a sensitivity of 63% and a specificity of 44%. In total, 50% had an updated CAD-score value ≤20. At this cut-off, sensitivity was 81% (95% CI 73% to 87%), specificity 53% (95% CI 50% to 56%), positive predictive value 16% (95% CI 13% to 18%) and negative predictive value 96% (95% CI 95% to 98%) for diagnosing haemodynamically significant CAD. Sound-based detection of CAD enables risk stratification superior to clinical risk scores. With a negative predictive value of 96%, this new acoustic rule-out system could potentially supplement clinical assessment to guide decisions on the need for further diagnostic investigation. ClinicalTrials.gov identifier NCT02264717; Results. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  19. Matrix method for acoustic levitation simulation.

    Science.gov (United States)

    Andrade, Marco A B; Perez, Nicolas; Buiochi, Flavio; Adamowski, Julio C

    2011-08-01

    A matrix method is presented for simulating acoustic levitators. A typical acoustic levitator consists of an ultrasonic transducer and a reflector. The matrix method is used to determine the potential for acoustic radiation force that acts on a small sphere in the standing wave field produced by the levitator. The method is based on the Rayleigh integral and it takes into account the multiple reflections that occur between the transducer and the reflector. The potential for acoustic radiation force obtained by the matrix method is validated by comparing the matrix method results with those obtained by the finite element method when using an axisymmetric model of a single-axis acoustic levitator. After validation, the method is applied in the simulation of a noncontact manipulation system consisting of two 37.9-kHz Langevin-type transducers and a plane reflector. The manipulation system allows control of the horizontal position of a small levitated sphere from -6 mm to 6 mm, which is done by changing the phase difference between the two transducers. The horizontal position of the sphere predicted by the matrix method agrees with the horizontal positions measured experimentally with a charge-coupled device camera. The main advantage of the matrix method is that it allows simulation of non-symmetric acoustic levitators without requiring much computational effort.

  20. Wiener variable step size and gradient spectral variance smoothing for double-talk-robust acoustic echo cancellation and acoustic feedback cancellation

    DEFF Research Database (Denmark)

    Gil-Cacho, Jose M.; Van Waterschoot, Toon; Moonen, Marc

    2014-01-01

    Double-talk (DT)-robust acoustic echo cancellation (AEC) and acoustic feedback cancellation (AFC) are needed in speech communication systems, e.g., in hands-free communication systems and hearing aids. In this paper, we derive a practical and computationally efficient algorithm based...... model and in colored non-stationary noise....

  1. XV-15 Structural-Acoustic Data

    Science.gov (United States)

    Lyle, Karen H.

    1997-01-01

    Tiltrotor aircraft are a potentially viable means of intercity travel. The tiltrotor is able to transport passengers relatively quickly from the center of a city to destinations within a 300-mile radius. For such vehicles to be commercially viable, the interior noise and vibration levels must be acceptable to the passengers. A review of the literature revealed very little structural-acoustic data related to the tiltrotor. For this reason, structural-acoustic measurements were taken aboard an XV-15 tiltrotor. The six flight conditions included five in level flight, nominally 140-220 knots, for airplane mode (nacelle at 0 degrees) and one out-of-ground-effect (OGE) hover (nacelle at 90 degrees). The flight test measurements included nine exterior surface pressures, five structural accelerations, and two interior pressures. These sensors were located near the tip path plane on the port side of the aircraft. One minute of data was acquired at each condition. The data is presented as time histories, autospectra, coherence functions, and cross-spectra. In general, for level flight, the measured data showed very little effect of forward flight speed except to change the amplitude of the response; however, the character of the response was found to be dependent on spatial location. In contrast, in the hover mode the spatial location had very little effect on the character of the response. Additionally, the report highlights: the coherence between the transducer data and the rotor tach signal; and transfer function calculations between the exterior pressures.

  2. Matching Impedances and Modes in Acoustic Levitation

    Science.gov (United States)

    Barmatz, M. B.

    1985-01-01

    Temperature differences accommodated with tunable coupler. Report discusses schemes for coupling sound efficiently from cool outside atmosphere into hot acoustic-levitation chamber. Theoretical studies have practical implications for material-processing systems that employ acoustic levitation.

  3. Acoustic Manipulation of Particles and Fluids in Microfluidic Systems

    OpenAIRE

    Johansson, Linda

    2009-01-01

    The downscaling and integration of biomedical analyses onto a single chip offers several advantages in speed, cost, parallelism and de-centralization. Acoustic radiation forces are attractive to use in these applications since they are strong, long-range and gentle. Lab-on-a-chip operations such as cell trapping, particle fluorescence activated cell sorting, fluid mixing and particle sorting performed by acoustic radiation forces are exploited in this thesis. Two different platforms are desig...

  4. Standard-target calibration of an acoustic backscatter system

    Science.gov (United States)

    Foote, Kenneth G.; Martini, Marinna A.

    2010-01-01

    The standard-target method used to calibrate scientific echo sounders and other scientific sonars by a single, solid elastic sphere is being adapted to acoustic backscatter (ABS) systems. Its first application, to the AQUAscat 1000, is described. The on-axis sensitivity and directional properties of transducer beams at three operating frequencies, nominally 1, 2.5, and 4 MHz, have been determined using a 10-mm-diameter sphere of tungsten carbide with 6% cobalt binder. Preliminary results are reported for the 1-MHz transducer. Their application to measurements of suspended sediment made in situ with the same device is described. This will enable the data to be expressed directly in physical units of volume backscattering.

  5. Acoustic source for generating an acoustic beam

    Science.gov (United States)

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian

    2016-05-31

    An acoustic source for generating an acoustic beam includes a housing; a plurality of spaced apart piezo-electric layers disposed within the housing; and a non-linear medium filling between the plurality of layers. Each of the plurality of piezoelectric layers is configured to generate an acoustic wave. The non-linear medium and the plurality of piezo-electric material layers have a matching impedance so as to enhance a transmission of the acoustic wave generated by each of plurality of layers through the remaining plurality of layers.

  6. Imaging and detection of mines from acoustic measurements

    Science.gov (United States)

    Witten, Alan J.; DiMarzio, Charles A.; Li, Wen; McKnight, Stephen W.

    1999-08-01

    A laboratory-scale acoustic experiment is described where a buried target, a hockey puck cut in half, is shallowly buried in a sand box. To avoid the need for source and receiver coupling to the host sand, an acoustic wave is generated in the subsurface by a pulsed laser suspended above the air-sand interface. Similarly, an airborne microphone is suspended above this interface and moved in unison with the laser. After some pre-processing of the data, reflections for the target, although weak, could clearly be identified. While the existence and location of the target can be determined by inspection of the data, its unique shape can not. Since target discrimination is important in mine detection, a 3D imaging algorithm was applied to the acquired acoustic data. This algorithm yielded a reconstructed image where the shape of the target was resolved.

  7. Damage Detection/Locating System Providing Thermal Protection

    Science.gov (United States)

    Woodard, Stanley E. (Inventor); Jones, Thomas W. (Inventor); Taylor, Bryant D. (Inventor); Qamar, A. Shams (Inventor)

    2010-01-01

    A damage locating system also provides thermal protection. An array of sensors substantially tiles an area of interest. Each sensor is a reflective-surface conductor having operatively coupled inductance and capacitance. A magnetic field response recorder is provided to interrogate each sensor before and after a damage condition. Changes in response are indicative of damage and a corresponding location thereof.

  8. Progressive phase trends in plates with embedded acoustic black holes.

    Science.gov (United States)

    Conlon, Stephen C; Feurtado, Philip A

    2018-02-01

    Acoustic black holes (ABHs) have been explored and demonstrated to be effective passive treatments for broadband noise and vibration control. Performance metrics for assessing damping concepts are often focused on maximizing structural damping loss factors. Optimally performing damping treatments can reduce the resonant response of a driven system well below the direct field response. This results in a finite structure whose vibration input-output response follows that of an infinite structure. The vibration mobility transfer functions between locations on a structure can be used to assess the structure's vibration response phase, and compare its phase response characteristics to those of idealized systems. This work experimentally explores the phase accumulation in finite plates, with and without embedded grids of ABHs. The measured results are compared and contrasted with theoretical results for finite and infinite uniform plates. Accumulated phase characteristics, their spatial dependence and limits, are examined for the plates and compared to theoretical estimates. The phase accumulation results show that the embedded acoustic black hole treatments can significantly enhance the damping of the plates to the point that their phase accumulation follows that of an infinite plate.

  9. Bubbles in piezo-acoustic inkjet printing

    NARCIS (Netherlands)

    Lohse, D.; Jeurissen, R.J.M.; de Jong, J.; Versluis, M.; Wijshoff, H.M.A.; van den Berg, M.; Reinten, H.

    2008-01-01

    Ink-jet printing is considered as the hitherto most successful application of microfluidics. A notorious problem in piezo-acoustic ink-jet systems is the formation of air bubbles during operation. They seriously disturb the acoustics and can cause the droplet formation to stop. We could show by a

  10. A micro-Doppler sonar for acoustic surveillance in sensor networks

    Science.gov (United States)

    Zhang, Zhaonian

    Wireless sensor networks have been employed in a wide variety of applications, despite the limited energy and communication resources at each sensor node. Low power custom VLSI chips implementing passive acoustic sensing algorithms have been successfully integrated into an acoustic surveillance unit and demonstrated for detection and location of sound sources. In this dissertation, I explore active and passive acoustic sensing techniques, signal processing and classification algorithms for detection and classification in a multinodal sensor network environment. I will present the design and characterization of a continuous-wave micro-Doppler sonar to image objects with articulated moving components. As an example application for this system, we use it to image gaits of humans and four-legged animals. I will present the micro-Doppler gait signatures of a walking person, a dog and a horse. I will discuss the resolution and range of this micro-Doppler sonar and use experimental results to support the theoretical analyses. In order to reduce the data rate and make the system amenable to wireless sensor networks, I will present a second micro-Doppler sonar that uses bandpass sampling for data acquisition. Speech recognition algorithms are explored for biometric identifications from one's gait, and I will present and compare the classification performance of the two systems. The acoustic micro-Doppler sonar design and biometric identification results are the first in the field as the previous work used either video camera or microwave technology. I will also review bearing estimation algorithms and present results of applying these algorithms for bearing estimation and tracking of moving vehicles. Another major source of the power consumption at each sensor node is the wireless interface. To address the need of low power communications in a wireless sensor network, I will also discuss the design and implementation of ultra wideband transmitters in a three dimensional

  11. Wind Turbine Generator System Acoustic Noise Test Report for the Gaia Wind 11-kW Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Huskey, A.

    2011-11-01

    This report details the acoustic noise test conducted on the Gaia-Wind 11-kW wind turbine at the National Wind Technology Center. The test turbine is a two- bladed, downwind wind turbine with a rated power of 11 kW. The test turbine was tested in accordance with the International Electrotechnical Commission standard, IEC 61400-11 Ed 2.1 2006-11 Wind Turbine Generator Systems -- Part 11 Acoustic Noise Measurement Techniques.

  12. Experimental investigation of acoustic agglomeration systems for fine particle control. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, D.T.; Lee, P.; Wegrzyn, J.; Chou, K.H.; Cheng, M.T.; Patel, S.

    1979-10-01

    The feasibility of using an acoustic agglomerator (AA) as a preconditioner in the upstream of conventional devices such as an electrostatic precipitator, a scrubber, a filter, or a cyclone are investigated. The objective is to agglomerate all finer particles into coarser ones in an acoustic agglomerator and then remove them more effectively by one of the conventional devices. Laboratory-scale experiments were performed using NH/sub 4/Cl and fly ash redispersed aerosols. Turbulence caused by intensive sound fields under standing-wave condition has been found to be extremely effective for aerosol agglomeration. The nature and the energy dissipation rate of the acoustic turbulence are determined by using hot-film (or hot-wire) anemometry and Fast Fourier Transform (FFT) data processing equipment. The root-mean-square turbulent velocity, which is directly proportional to acoustic agglomeration rate, is experimentally found to have a I/sup 1/2/(I: acoustic intensity) dependence, but is relatively independent of the acoustic frequency. The results obtained from this program show that acoustic agglomeration is effective as a particle pre-conditioner which can increase approximately one order of magnitude in mean particle diameter (2..mu..m ..-->.. 20..mu..m). As a flow-through standing wave device, it can be used to facilitate the removal of dust particles in a subsequent inertia base separation device.

  13. Novel Fiber-Optic Ring Acoustic Emission Sensor

    Directory of Open Access Journals (Sweden)

    Peng Wei

    2018-01-01

    Full Text Available Acoustic emission technology has been applied to many fields for many years. However, the conventional piezoelectric acoustic emission sensors cannot be used in extreme environments, such as those with heavy electromagnetic interference, high pressure, or strong corrosion. In this paper, a novel fiber-optic ring acoustic emission sensor is proposed. The sensor exhibits high sensitivity, anti-electromagnetic interference, and corrosion resistance. First, the principle of a novel fiber-optic ring sensor is introduced. Different from piezoelectric and other fiber acoustic emission sensors, this novel sensor includes both a sensing skeleton and a sensing fiber. Second, a heterodyne interferometric demodulating method is presented. In addition, a fiber-optic ring sensor acoustic emission system is built based on this method. Finally, fiber-optic ring acoustic emission experiments are performed. The novel fiber-optic ring sensor is glued onto the surface of an aluminum plate. The 150 kHz standard continuous sinusoidal signals and broken lead signals are successfully detected by the novel fiber-optic ring acoustic emission sensor. In addition, comparison to the piezoelectric acoustic emission sensor is performed, which shows the availability and reliability of the novel fiber-optic ring acoustic emission sensor. In the future, this novel fiber-optic ring acoustic emission sensor will provide a new route to acoustic emission detection in harsh environments.

  14. Passive Acoustic Source Localization at a Low Sampling Rate Based on a Five-Element Cross Microphone Array

    Directory of Open Access Journals (Sweden)

    Yue Kan

    2015-06-01

    Full Text Available Accurate acoustic source localization at a low sampling rate (less than 10 kHz is still a challenging problem for small portable systems, especially for a multitasking micro-embedded system. A modification of the generalized cross-correlation (GCC method with the up-sampling (US theory is proposed and defined as the US-GCC method, which can improve the accuracy of the time delay of arrival (TDOA and source location at a low sampling rate. In this work, through the US operation, an input signal with a certain sampling rate can be converted into another signal with a higher frequency. Furthermore, the optimal interpolation factor for the US operation is derived according to localization computation time and the standard deviation (SD of target location estimations. On the one hand, simulation results show that absolute errors of the source locations based on the US-GCC method with an interpolation factor of 15 are approximately from 1/15- to 1/12-times those based on the GCC method, when the initial same sampling rates of both methods are 8 kHz. On the other hand, a simple and small portable passive acoustic source localization platform composed of a five-element cross microphone array has been designed and set up in this paper. The experiments on the established platform, which accurately locates a three-dimensional (3D near-field target at a low sampling rate demonstrate that the proposed method is workable.

  15. Acoustically Induced Vibration of Structures: Reverberant Vs. Direct Acoustic Testing

    Science.gov (United States)

    Kolaini, Ali R.; O'Connell, Michael R.; Tsoi, Wan B.

    2009-01-01

    Large reverberant chambers have been used for several decades in the aerospace industry to test larger structures such as solar arrays and reflectors to qualify and to detect faults in the design and fabrication of spacecraft and satellites. In the past decade some companies have begun using direct near field acoustic testing, employing speakers, for qualifying larger structures. A limited test data set obtained from recent acoustic tests of the same hardware exposed to both direct and reverberant acoustic field testing has indicated some differences in the resulting structural responses. In reverberant acoustic testing, higher vibration responses were observed at lower frequencies when compared with the direct acoustic testing. In the case of direct near field acoustic testing higher vibration responses appeared to occur at higher frequencies as well. In reverberant chamber testing and direct acoustic testing, standing acoustic modes of the reverberant chamber or the speakers and spacecraft parallel surfaces can strongly couple with the fundamental structural modes of the test hardware. In this paper data from recent acoustic testing of flight hardware, that yielded evidence of acoustic standing wave coupling with structural responses, are discussed in some detail. Convincing evidence of the acoustic standing wave/structural coupling phenomenon will be discussed, citing observations from acoustic testing of a simple aluminum plate. The implications of such acoustic coupling to testing of sensitive flight hardware will be discussed. The results discussed in this paper reveal issues with over or under testing of flight hardware that could pose unanticipated structural and flight qualification issues. Therefore, it is of paramount importance to understand the structural modal coupling with standing acoustic waves that has been observed in both methods of acoustic testing. This study will assist the community to choose an appropriate testing method and test setup in

  16. The use of acoustic monitoring to manage concrete structures in the nuclear industry

    International Nuclear Information System (INIS)

    Paulson, P.O.; Tozser, O.; Wit, M. de

    2003-01-01

    Concrete and steel are widely used in containment vessels within the nuclear industry. Both are excellent acoustic transmitters. In many structures tensioned wire elements are used within containment structures. However, tensioned wire can be vulnerable to corrosion. To reduce the probability of corrosion sophisticated protection systems are used. To confirm that the design strength is available through time, extensive inspection and maintenance regimes are implemented. These regimes include tests to confirm the condition of the post-tensioning, and pressure tests (leak tests) to verify the performance of vessel. This paper presents an acoustic monitoring technology which uses widely distributed sensors to detect and locate wire failures using the energy released at failure. The technology has been used on a range of structures including post-tensioned concrete bridges, suspension bridges, buildings, pre-cast concrete cylinder pipelines (PCCP) and prestressed concrete containment vessels (PCCV), where it has increased confidence in structures and reduced maintenance costs. Where the level of ambient noise is low then SoundPrint acoustic monitoring can detect concrete cracking. This has been shown in PCCP pipelines, on laboratory test structures and also in nuclear structures. The programme has shown that distributed sensors can locate internal cracking well before there is any external evidence. Several projects have been completed on nuclear vessels. The first has been completed on an Electricite de France (EDF) concrete test pressure vessel at Civaux in France. The second at the Sandia PCCV Test Vessel in Albuquerque, New Mexico, USA, which involved the testing of a steel lined concrete vessel. The third was on a PCCV in Maryland, USA. Acoustic monitoring is also able to monitor the deterioration of post-tensioned concrete structures as a result of seismic activity. Summary details of a case history are presented. (author)

  17. Interior acoustic cloak

    Directory of Open Access Journals (Sweden)

    Wael Akl

    2014-12-01

    Full Text Available Acoustic cloaks have traditionally been intended to externally surround critical objects to render these objects acoustically invisible. However, in this paper, the emphasis is placed on investigating the application of the acoustic cloaks to the interior walls of acoustic cavities in an attempt to minimize the noise levels inside these cavities. In this manner, the acoustic cloaks can serve as a viable and efficient alternative to the conventional passive noise attenuation treatments which are invariably heavy and bulky. The transformation acoustics relationships that govern the operation of this class of interior acoustic cloaks are presented. Physical insights are given to relate these relationships to the reasons behind the effectiveness of the proposed interior acoustic cloaks. Finite element models are presented to demonstrate the characteristics of interior acoustic cloaks used in treating the interior walls of circular and square cavities both in the time and frequency domains. The obtained results emphasize the effectiveness of the proposed interior cloaks in eliminating the reflections of the acoustic waves from the walls of the treated cavities and thereby rendering these cavities acoustically quiet. It is important to note here that the proposed interior acoustic cloaks can find applications in acoustic cavities such as aircraft cabins and auditoriums as well as many other critical applications.

  18. A Permanent Automated Real-Time Passive Acoustic Monitoring System for Bottlenose Dolphin Conservation in the Mediterranean Sea.

    Directory of Open Access Journals (Sweden)

    Marco Brunoldi

    Full Text Available Within the framework of the EU Life+ project named LIFE09 NAT/IT/000190 ARION, a permanent automated real-time passive acoustic monitoring system for the improvement of the conservation status of the transient and resident population of bottlenose dolphin (Tursiops truncatus has been implemented and installed in the Portofino Marine Protected Area (MPA, Ligurian Sea. The system is able to detect the simultaneous presence of dolphins and boats in the area and to give their position in real time. This information is used to prevent collisions by diffusing warning messages to all the categories involved (tourists, professional fishermen and so on. The system consists of two gps-synchronized acoustic units, based on a particular type of marine buoy (elastic beacon, deployed about 1 km off the Portofino headland. Each one is equipped with a four-hydrophone array and an onboard acquisition system which can record the typical social communication whistles emitted by the dolphins and the sound emitted by boat engines. Signals are pre-filtered, digitized and then broadcast to the ground station via wi-fi. The raw data are elaborated to get the direction of the acoustic target to each unit, and hence the position of dolphins and boats in real time by triangulation.

  19. Capacitive system detects and locates fluid leaks

    Science.gov (United States)

    1966-01-01

    Electronic monitoring system automatically detects and locates minute leaks in seams of large fluid storage tanks and pipelines covered with thermal insulation. The system uses a capacitive tape-sensing element that is adhesively bonded over seams where fluid leaks are likely to occur.

  20. Data center equipment location and monitoring system

    DEFF Research Database (Denmark)

    2011-01-01

    A data center equipment location system includes both hardware and software to provide for location, monitoring, security and identification of servers and other equipment in equipment racks. The system provides a wired alternative to the wireless RFID tag system by using electronic ID tags...... connected to each piece of equipment, each electronic ID tag connected directly by wires to a equipment rack controller on the equipment rack. The equipment rack controllers then link over a local area network to a central control computer. The central control computer provides an operator interface......, and runs a software application program that communicates with the equipment rack controllers. The software application program of the central control computer stores IDs of the equipment rack controllers and each of its connected electronic ID tags in a database.; The software application program...

  1. Acoustic mapping of shallow water gas releases using shipborne multibeam systems

    Science.gov (United States)

    Urban, Peter; Köser, Kevin; Weiß, Tim; Greinert, Jens

    2015-04-01

    Water column imaging (WCI) shipborne multibeam systems are effective tools for investigating marine free gas (bubble) release. Like single- and splitbeam systems they are very sensitive towards gas bubbles in the water column, and have the advantage of the wide swath opening angle, 120° or more allowing a better mapping and possible 3D investigations of targets in the water column. On the downside, WCI data are degraded by specific noise from side-lobe effects and are usually not calibrated for target backscattering strength analysis. Most approaches so far concentrated on manual investigations of bubbles in the water column data. Such investigations allow the detection of bubble streams (flares) and make it possible to get an impression about the strength of detected flares/the gas release. Because of the subjective character of these investigations it is difficult to understand how well an area has been investigated by a flare mapping survey and subjective impressions about flare strength can easily be fooled by the many acoustic effects multibeam systems create. Here we present a semi-automated approach that uses the behavior of bubble streams in varying water currents to detect and map their exact source positions. The focus of the method is application of objective rules for flare detection, which makes it possible to extract information about the quality of the seepage mapping survey, perform automated noise reduction and create acoustic maps with quality discriminators indicating how well an area has been mapped.

  2. Divider plate leak inspections using an acoustic tool 'ALIS'

    International Nuclear Information System (INIS)

    Kowalewski, J.; Colbert, M.

    1998-01-01

    Divider plate leakage in the primary head of steam generators may be a contributor to high Reactor Inlet Header Temperature (RIHT) which can have a negative effect on the operation of a plant. A method to provide quick information of divider plate leakage can be very useful in helping operators to make timely and cost effective repair and maintenance decisions. As part of a CANDU Owners Group (COG) funded program, a novel acoustic tool for performing inspections in empty steam generators during a shutdown has been developed and successfully demonstrated by Ontario Hydro Technologies (OHT). The basic principle of this technique utilizes sound transmission through the leakage paths of a divider plate assembly for creating a graphic image which reveals the locations and relative sizes of leaks. This is accomplished by injecting one side of the primary head with a series of airborne, ultrasonic sound bursts while scanning the divider plates from the opposite side and collecting transmitted sound pressure levels. Once a scan is completed the results are processed and displayed graphically as a color mapping of the entire divider plate assembly showing an image of the leakage locations and relative severity. The special transducers of the acoustic leak inspection system (ALIS) are installed through the manways of the steam generator at both sides of the primary head. These are clamped to the tube sheet and operated from a convenient remote location within the containment building. This process minimizes radiation exposure of the workers, as well, it reduces risk of contamination of the ALIS equipment. The current version of this tool performs the scans by remote manual control. (author)

  3. Speech intelligibility for normal hearing and hearing-impaired listeners in simulated room acoustic conditions

    DEFF Research Database (Denmark)

    Arweiler, Iris; Dau, Torsten; Poulsen, Torben

    Speech intelligibility depends on many factors such as room acoustics, the acoustical properties and location of the signal and the interferers, and the ability of the (normal and impaired) auditory system to process monaural and binaural sounds. In the present study, the effect of reverberation...... on spatial release from masking was investigated in normal hearing and hearing impaired listeners using three types of interferers: speech shaped noise, an interfering female talker and speech-modulated noise. Speech reception thresholds (SRT) were obtained in three simulated environments: a listening room......, a classroom and a church. The data from the study provide constraints for existing models of speech intelligibility prediction (based on the speech intelligibility index, SII, or the speech transmission index, STI) which have shortcomings when reverberation and/or fluctuating noise affect speech...

  4. Industrial installation surveillance acoustic device

    International Nuclear Information System (INIS)

    Marini, Jean; Audenard, Bernard.

    1981-01-01

    The purpose of this invention is the detection of possible impacts of bodies migrating inside the installation, using acoustic sensors of the waves emitted at the time of impact of the migrating bodies. This device makes it possible to take into account only those acoustic signals relating to the impacts of bodies migrating in the area under surveillance, to the exclusion of any other acoustic or electric perturbing phenomenon. The invention has a preferential use in the case of a linear shape installation in which a fluid flows at high rate, such as a section of the primary system of a pressurized water nuclear reactor [fr

  5. Responsive acoustic surfaces

    DEFF Research Database (Denmark)

    Peters, Brady; Tamke, Martin; Nielsen, Stig Anton

    2011-01-01

    Acoustic performance is defined by the parameter of reverberation time; however, this does not capture the acoustic experience in some types of open plan spaces. As many working and learning activities now take place in open plan spaces, it is important to be able to understand and design...... for the acoustic conditions of these spaces. This paper describes an experimental research project that studied the design processes necessary to design for sound. A responsive acoustic surface was designed, fabricated and tested. This acoustic surface was designed to create specific sonic effects. The design...... was simulated using custom integrated acoustic software and also using Odeon acoustic analysis software. The research demonstrates a method for designing space- and sound-defining surfaces, defines the concept of acoustic subspace, and suggests some new parameters for defining acoustic subspaces....

  6. Considerations for acoustic emission monitoring of spherical Kevlar/epoxy composite pressure vessels

    Science.gov (United States)

    Hamstad, M. A.; Patterson, R. G.

    1977-01-01

    We are continuing to research the applications of acoustic emission testing for predicting burst pressure of filament-wound Kevlar 49/epoxy pressure vessels. This study has focused on three specific areas. The first area involves development of an experimental technique and the proper instrumentation to measure the energy given off by the acoustic emission transducer per acoustic emission burst. The second area concerns the design of a test fixture in which to mount the composite vessel so that the acoustic emission transducers are held against the outer surface of the composite. Included in this study area is the calibration of the entire test setup including couplant, transducer, electronics, and the instrument measuring the energy per burst. In the third and final area of this study, we consider the number, location, and sensitivity of the acoustic emission transducers used for proof testing composite pressure vessels.

  7. Flat acoustic lens by acoustic grating with curled slits

    KAUST Repository

    Peng, Pai

    2014-10-01

    We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry-Perot resonance.

  8. STRATEGIES TO INCREASE THE ACOUSTICAL QUALITY OF THE MOSQUES WITHOUT REINFORCEMENT SYSTEM

    Directory of Open Access Journals (Sweden)

    Ernaning Setiyowati

    2012-03-01

    Full Text Available One of the criteria of a good mosque is a good quality of building acoustic for some ibadah purposes, such as prayer and Friday speech. Mosques with medium size actually need no reinforcement system yet. Unfortunately, most of Indonesian mosques’ typological form were given very little attention about their acoustical problem. Such problems have found in almost every mosques. Therefore, some strategies are needed to fix the problem. Those strategies can be practiced on mosque’s interior surfaces such as ceiling, walls, and floor. One of the strategy is using the absorption material on the wall and the floor, beside using the reflection material on the ceiling. The placement of those materials depends on the path of the sound. The strategy can be used in every form of mosque with only  little different treatment in each mosque’s form. With this strategy, it is expected that mosques with medium size will no longer use the reinforcement system, yet the voice still can reach all of the jamaah. Thus this strategy can be used to reduce the use of energy in these buildings.

  9. Phononic fluidics: acoustically activated droplet manipulations

    Science.gov (United States)

    Reboud, Julien; Wilson, Rab; Bourquin, Yannyk; Zhang, Yi; Neale, Steven L.; Cooper, Jonathan M.

    2011-02-01

    Microfluidic systems have faced challenges in handling real samples and the chip interconnection to other instruments. Here we present a simple interface, where surface acoustic waves (SAWs) from a piezoelectric device are coupled into a disposable acoustically responsive microfluidic chip. By manipulating droplets, SAW technologies have already shown their potential in microfluidics, but it has been limited by the need to rely upon mixed signal generation at multiple interdigitated electrode transducers (IDTs) and the problematic resulting reflections, to allow complex fluid operations. Here, a silicon chip was patterned with phononic structures, engineering the acoustic field by using a full band-gap. It was simply coupled to a piezoelectric LiNbO3 wafer, propagating the SAW, via a thin film of water. Contrary to the use of unstructured superstrates, phononic metamaterials allowed precise spatial control of the acoustic energy and hence its interaction with the liquids placed on the surface of the chip, as demonstrated by simulations. We further show that the acoustic frequency influences the interaction between the SAW and the phononic lattice, providing a route to programme complex fluidic manipulation onto the disposable chip. The centrifugation of cells from a blood sample is presented as a more practical demonstration of the potential of phononic crystals to realize diagnostic systems.

  10. 30th International Acoustical Imaging Symposium

    CERN Document Server

    Jones, Joie; Lee, Hua

    2011-01-01

    The International Symposium on Acoustical Imaging is a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. This interdisciplinary Symposium has been taking place every two years since 1968. In the course of the years the proceedings volumes in the Acoustical Imaging Series have become a reference for cutting-edge research in the field. In 2009 the 30th International Symposium on Acoustical Imaging was held in Monterey, CA, USA, March 1-4. Offering both a broad perspective on the state-of-the-art as well as  in-depth research contributions by the specialists in the field, this Volume 30 in the Series contains an excellent collection of forty three papers presented in five major categories: Biomedical Imaging Acoustic Microscopy Non-Destructive Evaluation Systems Analysis Signal Analysis and Image Processing Audience Researchers in medical imaging and biomedical instrumentation experts.

  11. Strength Restoration of Cracked Sandstone and Coal under a Uniaxial Compression Test and Correlated Damage Source Location Based on Acoustic Emissions

    Science.gov (United States)

    Feng, Xiaowei; Zhang, Nong; Zheng, Xigui; Pan, Dongjiang

    2015-01-01

    Underground rock masses have shown a general trend of natural balance over billions of years of ground movement. Nonetheless, man-made underground constructions disturb this balance and cause rock stability failure. Fractured rock masses are frequently encountered in underground constructions, and this study aims to restore the strength of rock masses that have experienced considerable fracturing under uniaxial compression. Coal and sandstone from a deep-buried coal mine were chosen as experimental subjects; they were crushed by uniaxial compression and then carefully restored by a chemical adhesive called MEYCO 364 with an innovative self-made device. Finally, the restored specimens were crushed once again by uniaxial compression. Axial stress, axial strain, circumferential strain, and volumetric strain data for the entire process were fully captured and are discussed here. An acoustic emission (AE) testing system was adopted to cooperate with the uniaxial compression system to provide better definitions for crack closure thresholds, crack initiation thresholds, crack damage thresholds, and three-dimensional damage source locations in intact and restored specimens. Several remarkable findings were obtained. The restoration effects of coal are considerably better than those of sandstone because the strength recovery coefficient of the former is 1.20, whereas that of the latter is 0.33, which indicates that MEYCO 364 is particularly valid for fractured rocks whose initial intact peak stress is less than that of MEYCO 364. Secondary cracked traces of restored sandstone almost follow the cracked traces of the initial intact sandstone, and the final failure is mainly caused by decoupling between the adhesive and the rock mass. However, cracked traces of restored coal only partially follow the traces of intact coal, with the final failure of the restored coal being caused by both bonding interface decoupling and self-breakage in coal. Three-dimensional damage source

  12. Strength Restoration of Cracked Sandstone and Coal under a Uniaxial Compression Test and Correlated Damage Source Location Based on Acoustic Emissions.

    Directory of Open Access Journals (Sweden)

    Xiaowei Feng

    Full Text Available Underground rock masses have shown a general trend of natural balance over billions of years of ground movement. Nonetheless, man-made underground constructions disturb this balance and cause rock stability failure. Fractured rock masses are frequently encountered in underground constructions, and this study aims to restore the strength of rock masses that have experienced considerable fracturing under uniaxial compression. Coal and sandstone from a deep-buried coal mine were chosen as experimental subjects; they were crushed by uniaxial compression and then carefully restored by a chemical adhesive called MEYCO 364 with an innovative self-made device. Finally, the restored specimens were crushed once again by uniaxial compression. Axial stress, axial strain, circumferential strain, and volumetric strain data for the entire process were fully captured and are discussed here. An acoustic emission (AE testing system was adopted to cooperate with the uniaxial compression system to provide better definitions for crack closure thresholds, crack initiation thresholds, crack damage thresholds, and three-dimensional damage source locations in intact and restored specimens. Several remarkable findings were obtained. The restoration effects of coal are considerably better than those of sandstone because the strength recovery coefficient of the former is 1.20, whereas that of the latter is 0.33, which indicates that MEYCO 364 is particularly valid for fractured rocks whose initial intact peak stress is less than that of MEYCO 364. Secondary cracked traces of restored sandstone almost follow the cracked traces of the initial intact sandstone, and the final failure is mainly caused by decoupling between the adhesive and the rock mass. However, cracked traces of restored coal only partially follow the traces of intact coal, with the final failure of the restored coal being caused by both bonding interface decoupling and self-breakage in coal. Three

  13. Parametric Room Acoustic workflows with real-time acoustic simulation

    DEFF Research Database (Denmark)

    Parigi, Dario

    2017-01-01

    The paper investigates and assesses the opportunities that real-time acoustic simulation offer to engage in parametric acoustics workflow and to influence architectural designs from early design stages......The paper investigates and assesses the opportunities that real-time acoustic simulation offer to engage in parametric acoustics workflow and to influence architectural designs from early design stages...

  14. Acoustic manipulation: Bessel beams and active carriers

    Science.gov (United States)

    Rajabi, Majid; Mojahed, Alireza

    2017-10-01

    In this paper, we address the interaction of zero-order acoustic Bessel beams as an acoustic manipulation tool, with an active spherical shell, as a carrier in drug, agent, or material delivery systems, in order to investigate the controllability of exerted acoustic radiation force as the driver. The active body is comprised of a spherical elastic shell stimulated in its monopole mode of vibrations with the same frequency as the incident wave field via an internally bonded and spatially uniformly excited piezoelectric actuator. The main aim of this work is to examine the performance of a nondiffracting and self-reconstructing zero-order Bessel beam to obtain the full manipulability condition of active carriers in comparison with the case of a plane wave field. The results unveil some unique potentials of the Bessel beams in the company of active carriers, with emphasis on the consumed power of the actuation system. This paper will widen the path toward the single-beam robust acoustic manipulation techniques and may lead to the prospect of combined tweezers and fields, with applications in delivery systems, microswimmers, and trapper designs.

  15. Neural network AE source location apart from structure size and material

    Czech Academy of Sciences Publication Activity Database

    Chlada, Milan; Převorovský, Zdeněk; Blaháček, Michal

    2010-01-01

    Roč. 28, - (2010), s. 99-107 ISSN 0730-0050. [European Conference on Acoustic Emission Testing 2010 /29./. Vídeň, 08.09.2010-10.09.2010] R&D Projects: GA ČR(CZ) GAP104/10/1430; GA MPO(CZ) FR-TI1/274 Institutional research plan: CEZ:AV0Z20760514 Keywords : AE source location * artificial neural network * arrival time profiles Subject RIV: BI - Acoustics http://www.ndt.net/search/abstract.php3?AbsID=10828

  16. Acoustical topology optimization for Zwicker's loudness model - Application to noise barriers

    DEFF Research Database (Denmark)

    Kook, Junghwan; Koo, Kunmo; Hyun, Jaeyub

    2012-01-01

    acoustic properties may not represent adequate parameters for optimizing acoustic devices. In this paper, we first present a design method for acoustical topology optimization by considering human's subjective conception of sound. To consider human hearing characteristics. Zwicker's loudness is calculated...... according to DIN45631 (ISO 532B). The main objective of this work is to minimize the main specific loudness of a target critical band rate by optimizing the distribution of the reflecting material in a design domain. The Helmholtz equation is used to model acoustic wave propagation and, it is solved using...... the finite element method. The sensitivity of the main specific loudness is calculated using the adjoint variable method and the chain rule. To demonstrate the effectiveness of the proposed method, various examples of noise barriers are presented with different source and receiver locations. The results...

  17. Fine-scale acoustic telemetry reveals unexpected lake trout, Salvelinus namaycush, spawning habitats in northern Lake Huron, North America

    Science.gov (United States)

    Binder, Thomas; Farha, Steve A.; Thompson, Henry T.; Holbrook, Christopher; Bergstedt, Roger A.; Riley, Stephen; Bronte, Charles R.; He, Ji; Krueger, Charles C.

    2018-01-01

    Previous studies of lake trout, Salvelinus namaycush, spawning habitat in the Laurentian Great Lakes have used time- and labour-intensive survey methods and have focused on areas with historic observations of spawning aggregations and on habitats prejudged by researchers to be suitable for spawning. As an alternative, we used fine-scale acoustic telemetry to locate, describe and compare lake trout spawning habitats. Adult lake trout were implanted with acoustic transmitters and tracked during five consecutive spawning seasons in a 19–27 km2 region of the Drummond Island Refuge, Lake Huron, using the VEMCO Positioning System. Acoustic telemetry revealed discrete areas of aggregation on at least five reefs in the study area, subsequently confirmed by divers to contain deposited eggs. Notably, several identified spawning sites would likely not have been discovered using traditional methods because either they were too small and obscure to stand out on a bathymetric map or because they did not conform to the conceptual model of spawning habitat held by many biologists. Our most unique observation was egg deposition in gravel and rubble substrates located at the base of and beneath overhanging edges of large boulders. Spawning sites typically comprised <10% of the reef area and were used consistently over the 5-year study. Evaluation of habitat selection from the perspective of fish behaviour through use of acoustic transmitters offers potential to expand current conceptual models of critical spawning habitat.

  18. Location-aware News Recommendation System with Using Fuzzy Logic

    Directory of Open Access Journals (Sweden)

    Mehdi Nejati

    2016-10-01

    Full Text Available with release of a huge amount of news on the Internet and the trend of users to Web-based news services.it is necessary to have a recommendation system. To grab attentions to news, news services use a number of criteria that called news values and user location is an important factor for it. In this paper, LONEF is proposed as a tow stage recommendation system. In first stage news are ranked by user’s locations and in second stage news are recommended by location Preferences, recency, Trustworthiness, groups priorities and popularity. To reduce ambiguity these properties is used tow Mamdani fuzzy interference and case-based decision systems. In Mamdani fuzzy interference system, it is tried to increase the system speed by optimizing selection of rules and membership functions and because of ambiguous feedback implementation, a decision making system is used to enable better simulation of user’s activities. Performance of our proposed approach is demonstrated in the experiments on different news groups.

  19. Acoustic and Perceptual Effects of Dysarthria in Greek with a Focus on Lexical Stress

    Science.gov (United States)

    Papakyritsis, Ioannis

    The field of motor speech disorders in Greek is substantially underresearched. Additionally, acoustic studies on lexical stress in dysarthria are generally very rare (Kim et al. 2010). This dissertation examined the acoustic and perceptual effects of Greek dysarthria focusing on lexical stress. Additional possibly deviant speech characteristics were acoustically analyzed. Data from three dysarthric participants and matched controls was analyzed using a case study design. The analysis of lexical stress was based on data drawn from a single word repetition task that included pairs of disyllabic words differentiated by stress location. This data was acoustically analyzed in terms of the use of the acoustic cues for Greek stress. The ability of the dysarthric participants to signal stress in single words was further assessed in a stress identification task carried out by 14 naive Greek listeners. Overall, the acoustic and perceptual data indicated that, although all three dysarthric speakers presented with some difficulty in the patterning of stressed and unstressed syllables, each had different underlying problems that gave rise to quite distinct patterns of deviant speech characteristics. The atypical use of lexical stress cues in Anna's data obscured the prominence relations of stressed and unstressed syllables to the extent that the position of lexical stress was usually not perceptually transparent. Chris and Maria on the other hand, did not have marked difficulties signaling lexical stress location, although listeners were not 100% successful in the stress identification task. For the most part, Chris' atypical phonation patterns and Maria's very slow rate of speech did not interfere with lexical stress signaling. The acoustic analysis of the lexical stress cues was generally in agreement with the participants' performance in the stress identification task. Interestingly, in all three dysarthric participants, but more so in Anna, targets stressed on the 1st

  20. Tutorial on the Psychophysics and Technology of Virtual Acoustic Displays

    Science.gov (United States)

    Wenzel, Elizabeth M.; Null, Cynthia (Technical Monitor)

    1998-01-01

    Virtual acoustics, also known as 3-D sound and auralization, is the simulation of the complex acoustic field experienced by a listener within an environment. Going beyond the simple intensity panning of normal stereo techniques, the goal is to process sounds so that they appear to come from particular locations in three-dimensional space. Although loudspeaker systems are being developed, most of the recent work focuses on using headphones for playback and is the outgrowth of earlier analog techniques. For example, in binaural recording, the sound of an orchestra playing classical music is recorded through small mics in the two "ear canals" of an anthropomorphic artificial or "dummy" head placed in the audience of a concert hall. When the recorded piece is played back over headphones, the listener passively experiences the illusion of hearing the violins on the left and the cellos on the right, along with all the associated echoes, resonances, and ambience of the original environment. Current techniques use digital signal processing to synthesize the acoustical properties that people use to localize a sound source in space. Thus, they provide the flexibility of a kind of digital dummy head, allowing a more active experience in which a listener can both design and move around or interact with a simulated acoustic environment in real time. Such simulations are being developed for a variety of application areas including architectural acoustics, advanced human-computer interfaces, telepresence and virtual reality, navigation aids for the visually-impaired, and as a test bed for psychoacoustical investigations of complex spatial cues. The tutorial will review the basic psychoacoustical cues that determine human sound localization and the techniques used to measure these cues as Head-Related Transfer Functions (HRTFs) for the purpose of synthesizing virtual acoustic environments. The only conclusive test of the adequacy of such simulations is an operational one in which

  1. TH-CD-201-06: Experimental Characterization of Acoustic Signals Generated in Water Following Clinical Photon and Electron Beam Irradiation

    International Nuclear Information System (INIS)

    Hickling, S; El Naqa, I

    2016-01-01

    Purpose: Previous work has demonstrated the detectability of acoustic waves induced following the irradiation of high density metals with radiotherapy linac photon beams. This work demonstrates the ability to experimentally detect such acoustic signals following both photon and electron irradiation in a more radiotherapy relevant material. The relationship between induced acoustic signal properties in water and the deposited dose distribution is explored, and the feasibility of exploiting such signals for radiotherapy dosimetry is demonstrated. Methods: Acoustic waves were experimentally induced in a water tank via the thermoacoustic effect following a single pulse of photon or electron irradiation produced by a clinical linac. An immersion ultrasound transducer was used to detect these acoustic waves in water and signals were read out on an oscilloscope. Results: Peaks and troughs in the detected acoustic signals were found to correspond to the location of gradients in the deposited dose distribution following both photon and electron irradiation. Signal amplitude was linearly related to the dose per pulse deposited by photon or electron beams at the depth of detection. Flattening filter free beams induced large acoustic signals, and signal amplitude decreased with depth after the depth of maximum dose. Varying the field size resulted in a temporal shift of the acoustic signal peaks and a change in the detected signal frequency. Conclusion: Acoustic waves can be detected in a water tank following irradiation by linac photon and electron beams with basic electronics, and have characteristics related to the deposited dose distribution. The physical location of dose gradients and the amount of dose deposited can be inferred from the location and magnitude of acoustic signal peaks. Thus, the detection of induced acoustic waves could be applied to photon and electron water tank and in vivo dosimetry. This work was supported in part by CIHR grants MOP-114910 and MOP

  2. Experimental demonstration of the Rayleigh acoustic viscous boundary layer theory.

    Science.gov (United States)

    Castrejón-Pita, J R; Castrejón-Pita, A A; Huelsz, G; Tovar, R

    2006-03-01

    Amplitude and phase velocity measurements on the laminar oscillatory viscous boundary layer produced by acoustic waves are presented. The measurements were carried out in acoustic standing waves in air with frequencies of 68.5 and 114.5 Hz using laser Doppler anemometry and particle image velocimetry. The results obtained by these two techniques are in good agreement with the predictions made by the Rayleigh viscous boundary layer theory and confirm the existence of a local maximum of the velocity amplitude and its expected location.

  3. Acoustics and Hearing

    CERN Document Server

    Damaske, Peter

    2008-01-01

    When one listens to music at home, one would like to have an acoustic impression close to that of being in the concert hall. Until recently this meant elaborate multi-channelled sound systems with 5 or more speakers. But head-related stereophony achieves the surround-sound effect in living rooms with only two loudspeakers. By virtue of their slight directivity as well as an electronic filter the limitations previously common to two-speaker systems can be overcome and this holds for any arbitrary two-channel recording. The book also investigates the question of how a wide and diffuse sound image can arise in concert halls and shows that the quality of concert halls decisively depends on diffuse sound images arising in the onset of reverberation. For this purpose a strong onset of reverberation is modified in an anechoic chamber by electroacoustic means. Acoustics and Hearing proposes ideas concerning signal processing in the auditory system that explain the measured results and the resultant sound effects plea...

  4. Enhanced acoustic sensing through wave compression and pressure amplification in anisotropic metamaterials.

    Science.gov (United States)

    Chen, Yongyao; Liu, Haijun; Reilly, Michael; Bae, Hyungdae; Yu, Miao

    2014-10-15

    Acoustic sensors play an important role in many areas, such as homeland security, navigation, communication, health care and industry. However, the fundamental pressure detection limit hinders the performance of current acoustic sensing technologies. Here, through analytical, numerical and experimental studies, we show that anisotropic acoustic metamaterials can be designed to have strong wave compression effect that renders direct amplification of pressure fields in metamaterials. This enables a sensing mechanism that can help overcome the detection limit of conventional acoustic sensing systems. We further demonstrate a metamaterial-enhanced acoustic sensing system that achieves more than 20 dB signal-to-noise enhancement (over an order of magnitude enhancement in detection limit). With this system, weak acoustic pulse signals overwhelmed by the noise are successfully recovered. This work opens up new vistas for the development of metamaterial-based acoustic sensors with improved performance and functionalities that are highly desirable for many applications.

  5. Demodulation of acoustic telemetry binary phase shift keying signal based on high-order Duffing system

    International Nuclear Information System (INIS)

    Yan Bing-Nan; Liu Chong-Xin; Ni Jun-Kang; Zhao Liang

    2016-01-01

    In order to grasp the downhole situation immediately, logging while drilling (LWD) technology is adopted. One of the LWD technologies, called acoustic telemetry, can be successfully applied to modern drilling. It is critical for acoustic telemetry technology that the signal is successfully transmitted to the ground. In this paper, binary phase shift keying (BPSK) is used to modulate carrier waves for the transmission and a new BPSK demodulation scheme based on Duffing chaos is investigated. Firstly, a high-order system is given in order to enhance the signal detection capability and it is realized through building a virtual circuit using an electronic workbench (EWB). Secondly, a new BPSK demodulation scheme is proposed based on the intermittent chaos phenomena of the new Duffing system. Finally, a system variable crossing zero-point equidistance method is proposed to obtain the phase difference between the system and the BPSK signal. Then it is determined that the digital signal transmitted from the bottom of the well is ‘0’ or ‘1’. The simulation results show that the demodulation method is feasible. (paper)

  6. Detection and Location of Structural Degradation in Mechanical Systems

    International Nuclear Information System (INIS)

    Blakeman, E.D.; Damiano, B.; Phillips, L.D.

    1999-01-01

    The investigation of a diagnostic method for detecting and locating the source of structural degradation in a mechanical system is described in this paper. The diagnostic method uses a mathematical model of the mechanical system to determine relationships between system parameters and measurable spectral features. These relationships are incorporated into a neural network, which associates measured spectral features with system parameters. Condition diagnosis is performed by presenting the neural network with measured spectral features and comparing the system parameters estimated by the neural network to previously estimated values. Changes in the estimated system parameters indicate the location and severity of degradation in the mechanical system

  7. Ultrasonic superlensing jets and acoustic-fork sheets

    Energy Technology Data Exchange (ETDEWEB)

    Mitri, F.G., E-mail: F.G.Mitri@ieee.org

    2017-05-18

    Focusing acoustical (and optical) beams beyond the diffraction limit has remained a major challenge in imaging instruments and systems, until recent advances on “hyper” or “super” lensing and higher-resolution imaging techniques have shown the counterintuitive violation of this rule under certain circumstances. Nonetheless, the proposed technologies of super-resolution acoustical focusing beyond the diffraction barrier require complex tools such as artificially engineered metamaterials, and other hardware equipment that may not be easily synthesized or manufactured. The present contribution therefore suggests a simple and reliable method of using a sound-penetrable circular cylinder lens illuminated by a nonparaxial Gaussian acoustical sheet (i.e. finite beam in 2D) to produce non-evanescent ultrasonic superlensing jets (or bullets) and acoustical ‘snail-fork’ shaped wavefronts with limited diffraction. The generalized (near-field) scattering theory for acoustical sheets of arbitrary wavefronts and incidence is utilized to synthesize the incident beam based upon the angular spectrum decomposition method and the multipole expansion method in cylindrical wave functions to compute the scattered pressure around the cylinder with particular emphasis on its physical properties. The results show that depending on the beam and lens parameters, a tight focusing (with dimensions much smaller than the beam waist) can be achieved. Subwavelength resolution can be also achieved by selecting a lens material with a speed of sound exceeding that of the host fluid medium. The ultrasonic superlensing jets provide the impetus to develop improved subwavelength microscopy and acoustical image-slicing systems, cell lysis and surgery, and photoacoustic imaging to name a few examples. Moreover, an acoustical fork-sheet generation may open innovative avenues in reconfigurable on-chip micro/nanoparticle tweezers and surface acoustic waves devices. - Highlights: • Ultrasonic

  8. Acoustic monitoring system to quantify ingestive behavior of free-grazing cattle

    Science.gov (United States)

    Methods to estimate intake in grazing livestock include using markers, visual observation, mechanical sensors that respond to jaw movement and acoustic recording. In most of the acoustic monitoring studies, the microphone is inverted on the forehead of the grazing livestock and the skull is utilize...

  9. Multi-crack imaging using nonclassical nonlinear acoustic method

    International Nuclear Information System (INIS)

    Zhang Lue; Zhang Ying; Liu Xiao-Zhou; Gong Xiu-Fen

    2014-01-01

    Solid materials with cracks exhibit the nonclassical nonlinear acoustical behavior. The micro-defects in solid materials can be detected by nonlinear elastic wave spectroscopy (NEWS) method with a time-reversal (TR) mirror. While defects lie in viscoelastic solid material with different distances from one another, the nonlinear and hysteretic stress—strain relation is established with Preisach—Mayergoyz (PM) model in crack zone. Pulse inversion (PI) and TR methods are used in numerical simulation and defect locations can be determined from images obtained by the maximum value. Since false-positive defects might appear and degrade the imaging when the defects are located quite closely, the maximum value imaging with a time window is introduced to analyze how defects affect each other and how the fake one occurs. Furthermore, NEWS-TR-NEWS method is put forward to improve NEWS-TR scheme, with another forward propagation (NEWS) added to the existing phases (NEWS and TR). In the added phase, scanner locations are determined by locations of all defects imaged in previous phases, so that whether an imaged defect is real can be deduced. NEWS-TR-NEWS method is proved to be effective to distinguish real defects from the false-positive ones. Moreover, it is also helpful to detect the crack that is weaker than others during imaging procedure. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  10. The near-field acoustic levitation of high-mass rotors

    International Nuclear Information System (INIS)

    Hong, Z. Y.; Lü, P.; Geng, D. L.; Zhai, W.; Yan, N.; Wei, B.

    2014-01-01

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope

  11. The near-field acoustic levitation of high-mass rotors

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Z. Y.; Lü, P.; Geng, D. L.; Zhai, W.; Yan, N.; Wei, B., E-mail: bbwei@nwpu.edu.cn [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)

    2014-10-15

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

  12. The near-field acoustic levitation of high-mass rotors.

    Science.gov (United States)

    Hong, Z Y; Lü, P; Geng, D L; Zhai, W; Yan, N; Wei, B

    2014-10-01

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

  13. Acoustic Particle Detection with the ANTARES Detector

    Directory of Open Access Journals (Sweden)

    M. Neff

    2010-01-01

    Full Text Available The (Antares Modules for Acoustic Detection Under the Sea AMADEUS system within the (Astronomy with a Neutrino Telescope and Abyss environmental RESsearch ANTARES neutrino telescope is designed to investigate detection techniques for acoustic signals produced by particle cascades. While passing through a liquid a cascade deposits energy and produces a measurable pressure pulse. This can be used for the detection of neutrinos with energies exceeding 1018 eV. The AMADEUS setup consists of 36 hydrophones grouped in six local clusters measuring about one cubic meter each. This article focuses on acoustic particle detection, the hardware of the AMADEUS detector and techniques used for acoustic signal processing.

  14. Acoustic Particle Detection with the ANTARES Detector

    Directory of Open Access Journals (Sweden)

    Richardt C

    2010-01-01

    Full Text Available The (Antares Modules for Acoustic Detection Under the Sea AMADEUS system within the (Astronomy with a Neutrino Telescope and Abyss environmental RESsearch ANTARES neutrino telescope is designed to investigate detection techniques for acoustic signals produced by particle cascades. While passing through a liquid a cascade deposits energy and produces a measurable pressure pulse. This can be used for the detection of neutrinos with energies exceeding  eV. The AMADEUS setup consists of 36 hydrophones grouped in six local clusters measuring about one cubic meter each. This article focuses on acoustic particle detection, the hardware of the AMADEUS detector and techniques used for acoustic signal processing.

  15. A numerical study on acoustic behavior in gas turbine combustor with acoustic resonator

    International Nuclear Information System (INIS)

    Park, I Sun; Sohn, Chae Hoon

    2005-01-01

    Acoustic behavior in gas turbine combustor with acoustic resonator is investigated numerically by adopting linear acoustic analysis. Helmholtz-type resonator is employed as acoustic resonator to suppress acoustic instability passively. The tuning frequency of acoustic resonator is adjusted by varying its length. Through harmonic analysis, acoustic-pressure responses of chamber to acoustic excitation are obtained and the resonant acoustic modes are identified. Acoustic damping effect of acoustic resonator is quantified by damping factor. As the tuning frequency of acoustic resonator approaches the target frequency of the resonant mode to be suppressed, mode split from the original resonant mode to lower and upper modes appears and thereby complex patterns of acoustic responses show up. Considering mode split and damping effect as a function of tuning frequency, it is desirable to make acoustic resonator tuned to broad-band frequencies near the maximum frequency of those of the possible upper modes

  16. Acoustical Imaging

    CERN Document Server

    Litniewski, Jerzy; Kujawska, Tamara; 31st International Symposium on Acoustical Imaging

    2012-01-01

    The International Symposium on Acoustical Imaging is a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. This interdisciplinary Symposium has been taking place continuously since 1968. In the course of the years the proceedings volumes in the Acoustical Imaging Series have become a reference for cutting-edge research in the field. In 2011 the 31st International Symposium on Acoustical Imaging was held in Warsaw, Poland, April 10-13. Offering both a broad perspective on the state-of-the-art as well as  in-depth research contributions by the specialists in the field, this Volume 31 in the Series contains an excellent collection of papers in six major categories: Biological and Medical Imaging Physics and Mathematics of Acoustical Imaging Acoustic Microscopy Transducers and Arrays Nondestructive Evaluation and Industrial Applications Underwater Imaging

  17. Acoustic and elastic properties of Sn2P2S6 crystals

    International Nuclear Information System (INIS)

    Mys, O; Martynyuk-Lototska, I; Vlokh, R; Grabar, A

    2009-01-01

    We present the results concerned with acoustic and elastic properties of Sn 2 P 2 S 6 crystals. The complete matrices of elastic stiffness and compliance coefficients are determined in both the crystallographic coordinate system and the system associated with eigenvectors of the elastic stiffness tensor. The acoustic slowness surfaces are constructed and the propagation and polarization directions of the slowest acoustic waves promising for acousto-optic interactions are determined on this basis. The acoustic obliquity angle and the deviation of polarization of the acoustic waves from purely transverse or longitudinal states are quantitatively analysed.

  18. Acoustic and elastic properties of Sn(2)P(2)S(6) crystals.

    Science.gov (United States)

    Mys, O; Martynyuk-Lototska, I; Grabar, A; Vlokh, R

    2009-07-01

    We present the results concerned with acoustic and elastic properties of Sn(2)P(2)S(6) crystals. The complete matrices of elastic stiffness and compliance coefficients are determined in both the crystallographic coordinate system and the system associated with eigenvectors of the elastic stiffness tensor. The acoustic slowness surfaces are constructed and the propagation and polarization directions of the slowest acoustic waves promising for acousto-optic interactions are determined on this basis. The acoustic obliquity angle and the deviation of polarization of the acoustic waves from purely transverse or longitudinal states are quantitatively analysed.

  19. Acoustic excitation of mechatronic systems by diffuse acoustic sound fields; Numerical predictions and measurements.

    NARCIS (Netherlands)

    Roozen, N.B.

    2006-01-01

    With the accuracy of metrology frame applications entering the nanometer-range, the necessity arises totackle all types of disturbances. In the process of estimating the relative importance of the different types of disturbances on the machine accuracy, also called dynamic error budgeting, acoustic

  20. Speech Intelligibility Advantages using an Acoustic Beamformer Display

    Science.gov (United States)

    Begault, Durand R.; Sunder, Kaushik; Godfroy, Martine; Otto, Peter

    2015-01-01

    A speech intelligibility test conforming to the Modified Rhyme Test of ANSI S3.2 "Method for Measuring the Intelligibility of Speech Over Communication Systems" was conducted using a prototype 12-channel acoustic beamformer system. The target speech material (signal) was identified against speech babble (noise), with calculated signal-noise ratios of 0, 5 and 10 dB. The signal was delivered at a fixed beam orientation of 135 deg (re 90 deg as the frontal direction of the array) and the noise at 135 deg (co-located) and 0 deg (separated). A significant improvement in intelligibility from 57% to 73% was found for spatial separation for the same signal-noise ratio (0 dB). Significant effects for improved intelligibility due to spatial separation were also found for higher signal-noise ratios (5 and 10 dB).

  1. Real-time locating systems (RTLS) in healthcare: a condensed primer.

    Science.gov (United States)

    Kamel Boulos, Maged N; Berry, Geoff

    2012-06-28

    Real-time locating systems (RTLS, also known as real-time location systems) have become an important component of many existing ubiquitous location aware systems. While GPS (global positioning system) has been quite successful as an outdoor real-time locating solution, it fails to repeat this success indoors. A number of RTLS technologies have been used to solve indoor tracking problems. The ability to accurately track the location of assets and individuals indoors has many applications in healthcare. This paper provides a condensed primer of RTLS in healthcare, briefly covering the many options and technologies that are involved, as well as the various possible applications of RTLS in healthcare facilities and their potential benefits, including capital expenditure reduction and workflow and patient throughput improvements. The key to a successful RTLS deployment lies in picking the right RTLS option(s) and solution(s) for the application(s) or problem(s) at hand. Where this application-technology match has not been carefully thought of, any technology will be doomed to failure or to achieving less than optimal results.

  2. Preliminary Modeling of Acoustic Detection Capability for the Drifting Arctic Monitoring System

    Science.gov (United States)

    2015-02-01

    Sedimentary Basins in the Arctic, Polarforschung, 69, 243–249. [22] Poore, Richard Z, Ishman, Scott E, Phillips, R Lawrence, and McNeil, David H (1994...93, 1784. [28] Metzler, Adam M, Collis , Jon M, and Siegmann, William L (2012), Modeling low-frequency seismo-acoustic propagation in the Arctic using a...Atlantic. [50] Shnidman, David A (1998), Binary integration for Swerling target fluctuations, Aerospace and Electronic Systems, IEEE Transactions on

  3. Streptavidin Modified ZnO Film Bulk Acoustic Resonator for Detection of Tumor Marker Mucin 1

    Science.gov (United States)

    Zheng, Dan; Guo, Peng; Xiong, Juan; Wang, Shengfu

    2016-09-01

    A ZnO-based film bulk acoustic resonator has been fabricated using a magnetron sputtering technology, which was employed as a biosensor for detection of mucin 1. The resonant frequency of the thin-film bulk acoustic resonator was located near at 1503.3 MHz. The average electromechanical coupling factor {K}_{eff}^2 and quality factor Q were 2.39 % and 224, respectively. Using the specific binding system of avidin-biotin, the streptavidin was self-assembled on the top gold electrode as the sensitive layer to indirectly test the MUC1 molecules. The resonant frequency of the biosensor decreases in response to the mass loading in range of 20-500 nM. The sensor modified with the streptavidin exhibits a high sensitivity of 4642.6 Hz/nM and a good selectivity.

  4. Topological Acoustics

    Science.gov (United States)

    Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

    2015-03-01

    The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers.

  5. Development of an acoustic transceiver for the KM3NeT positioning system

    Energy Technology Data Exchange (ETDEWEB)

    Larosa, G., E-mail: giula@doctor.upv.es [Universitat Politèctnica de València, Institut d’Investigació per a la Gestiò Integrada de Zones Costaneres (IGIC), C/Paranimf 1, 46730 Gandia, València (Spain); Ardid, M.; Llorens, C.D.; Bou-Cabo, M.; Martínez-Mora, J.A.; Adrián-Martínez, S. [Universitat Politèctnica de València, Institut d’Investigació per a la Gestiò Integrada de Zones Costaneres (IGIC), C/Paranimf 1, 46730 Gandia, València (Spain)

    2013-10-11

    In this paper we describe an acoustic transceiver developed for the KM3NeT positioning system. The acoustic transceiver is composed of a commercial free flooded transducer, which works mainly in the 20–40 kHz frequency range and withstands high pressures (up to 500 bars). A sound emission board was developed that is adapted to the characteristics of the transducer and meets all requirements: low power consumption, high intensity of emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring the receiving signals with very good timing precision. The results of the different tests made with the transceiver in the laboratory and shallow sea water are described, as well as, the activities for its integration in the Instrumentation Line of the ANTARES neutrino telescope and in a NEMO tower for the in situ tests.

  6. Escaping the maze: micro-swimmers using acoustic forces to navigate

    Science.gov (United States)

    Louf, Jean-Francois; Dollet, Benjamin; Stephan, Olivier; Marmottant, Philippe

    2017-11-01

    The goal of this study is to make 3D micro-swimmers containing a bubble that can be stimulated with acoustic waves emitted by a transducer, and whose direction is accurately controlled. By using 3D micro-fabrication techniques, we designed 40x40 μm swimmers with a trapped air bubble. We then applied acoustic vibration to the bubble, which generates a strong steady flow (1-100 mm/s) behind it, an effect referred as acoustic streaming. However, independently from the orientation of the bubble and thus from the flow, the motion of the swimmer is found to be towards the transducer. This suggests that primary Bjerknes forces, i.e. acoustic radiation forces, are involved. Subsequently, using different transducers located at different points, we could be able to navigate the swimmer in a chosen direction. The next step of our study is to use a stationary wave and Bjerknes forces to bring encapsulated objects in a pressure node. Without bubbles, the effect of acoustic streaming on big objects of more than a micrometer is not sufficient to generate motion. However, with the presence of bubbles, our swimmers should be able to move. ERC BUBBLEBOOST.

  7. Simultaneous acoustic and dielectric real time curing monitoring of epoxy systems

    Science.gov (United States)

    Gkikas, G.; Saganas, Ch.; Grammatikos, S. A.; Aggelis, D. G.; Paipetis, A. S.

    2012-04-01

    The attainment of structural integrity of the reinforcing matrix in composite materials is of primary importance for the final properties of the composite structure. The detailed monitoring of the curing process on the other hand is paramount (i) in defining the optimal conditions for the impregnation of the reinforcement by the matrix (ii) in limiting the effects of the exotherm produced by the polymerization reaction which create unwanted thermal stresses and (iii) in securing optimal behavior in matrix controlled properties, such as off axis or shear properties and in general the durability of the composite. Dielectric curing monitoring is a well known technique for distinguishing between the different stages of the polymerization of a typical epoxy system. The technique successfully predicts the gelation and the vitrification of the epoxy and has been extended for the monitoring of prepregs. Recent work has shown that distinct changes in the properties of the propagated sound in the epoxy which undergoes polymerization is as well directly related to the gelation and vitrification of the resin, as well as to the attainment of the final properties of the resin system. In this work, a typical epoxy is simultaneously monitored using acoustic and dielectric methods. The system is isothermally cured in an oven to avoid effects from the polymerization exotherm. Typical broadband sensors are employed for the acoustic monitoring, while flat interdigital sensors are employed for the dielectric scans. All stages of the polymerization process were successfully monitored and the validity of both methods was cross checked and verified.

  8. EnEx-RANGE - Robust autonomous Acoustic Navigation in Glacial icE

    Science.gov (United States)

    Heinen, Dirk; Eliseev, Dmitry; Henke, Christoph; Jeschke, Sabina; Linder, Peter; Reuter, Sebastian; Schönitz, Sebastian; Scholz, Franziska; Weinstock, Lars Steffen; Wickmann, Stefan; Wiebusch, Christopher; Zierke, Simon

    2017-03-01

    Within the Enceladus Explorer Initiative of the DLR Space Administration navigation technologies for a future space mission are in development. Those technologies are the basis for the search for extraterrestrial life on the Saturn moon Enceladus. An autonomous melting probe, the EnEx probe, aims to extract a liquid sample from a water reservoir below the icy crust. A first EnEx probe was developed and demonstrated in a terrestrial scenario at the Bloodfalls, Taylor Glacier, Antarctica in November 2014. To enable navigation in glacier ice two acoustic systems were integrated into the probe in addition to conventional navigation technologies. The first acoustic system determines the position of the probe during the run based on propagation times of acoustic signals from emitters at reference positions at the glacier surface to receivers in the probe. The second system provides information about the forefield of the probe. It is based on sonographic principles with phased array technology integrated in the probe's melting head. Information about obstacles or sampling regions in the probe's forefield can be acquired. The development of both systems is now continued in the project EnEx-RANGE. The emitters of the localization system are replaced by a network of intelligent acoustic enabled melting probes. These localize each other by means of acoustic signals and create the reference system for the EnEx probe. This presentation includes the discussion of the intelligent acoustic network, the acoustic navigation systems of the EnEx probe and results of terrestrial tests.

  9. Study on Leak Detection of the Pipeline System by Acoustic Emission

    International Nuclear Information System (INIS)

    Yoon, D. J.; Kim, C. J.

    1987-01-01

    Leak detection testing for the pipeline system was performed by the acoustic emission method. It was found that the detected signal spectrum was influenced by the frequency response of sensors and pressure changes. AE parameters and frequency spectrum distributions were used to analyze the leak signals. The slope rise time of AE parameters were the important factors for distinguishing leak signals. The amplitude of leak signal was more affected by the changes of leak, rate and pressure than those of leak type

  10. Physical acoustics principles and methods

    CERN Document Server

    Mason, Warren P

    2012-01-01

    Physical Acoustics: Principles and Methods, Volume IV, Part B: Applications to Quantum and Solid State Physics provides an introduction to the various applications of quantum mechanics to acoustics by describing several processes for which such considerations are essential. This book discusses the transmission of sound waves in molten metals. Comprised of seven chapters, this volume starts with an overview of the interactions that can happen between electrons and acoustic waves when magnetic fields are present. This text then describes acoustic and plasma waves in ionized gases wherein oscillations are subject to hydrodynamic as well as electromagnetic forces. Other chapters examine the resonances and relaxations that can take place in polymer systems. This book discusses as well the general theory of the interaction of a weak sinusoidal field with matter. The final chapter describes the sound velocities in the rocks composing the Earth. This book is a valuable resource for physicists and engineers.

  11. Acoustic Emission Weld Monitoring in the 2195 Aluminum-Lithium Alloy

    Science.gov (United States)

    Walker, James L.

    2005-01-01

    Due to its low density, the 2195 aluminum-lithium alloy was developed as a replacement for alloy 2219 in the Space Shuttle External Tank (ET). The external tank is the single largest component of the space shuttle system. It is 154 feet long and 27.6 feet in diameter, and serves as the structural backbone for the shuttle during launch, absorbing most of the 7 million plus pounds of thrust produced. The almost 4% decrease in density between the two materials provides an extra 7500 pounds of payload capacity necessary to put the International Space Station components into orbit. The ET is an all-welded structure; hence, the requirement is for up to five rewelds without hot cracking. Unfortunately, hot cracking during re-welding or repair operations was occurring and had to be dealt with before the new super lightweight tank could be used. Weld metal porosity formation was also of concern because it leads to hot cracking during weld repairs. Accordingly, acoustic emission (AE) nondestructive testing was employed to monitor the formation of porosity and hot cracks in order to select the best filler metal and optimize the weld schedule. The purpose of this work is to determine the feasibility of detecting hot cracking in welded aluminum-lithium (Al-Li) structures through the analysis of acoustic emission data. By acoustically characterizing the effects of reheating during a repair operation, the potential for hidden flaws coalescing and becoming "unstable" as the panel is repaired could be reduced. Identification of regions where microcrack growth is likely to occur and the location of active flaw growth in the repair weld will provide the welder with direct feedback as to the current weld quality enabling adjustments to the repair process be made in the field. An acoustic emission analysis of the source mechanisms present during welding has been conducted with the goals of locating regions in the weld line that are susceptible to damage from a repair operation

  12. Acoustic Seabed Characterization of the Porcupine Bank, Irish Margin

    Science.gov (United States)

    O'Toole, Ronan; Monteys, Xavier

    2010-05-01

    The Porcupine Bank represents a large section of continental shelf situated west of the Irish landmass, located in water depths ranging between 150 and 500m. Under the Irish National Seabed Survey (INSS 1999-2006) this area was comprehensively mapped, generating multiple acoustic datasets including high resolution multibeam echosounder data. The unique nature of the area's datasets in terms of data density, consistency and geographic extent has allowed the development of a large-scale integrated physical characterization of the Porcupine Bank for multidisciplinary applications. Integrated analysis of backscatter and bathymetry data has resulted in a baseline delineation of sediment distribution, seabed geology and geomorphological features on the bank, along with an inclusive set of related database information. The methodology used incorporates a variety of statistical techniques which are necessary in isolating sonar system artefacts and addressing sonar geometry related issues. A number of acoustic backscatter parameters at several angles of incidence have been analysed in order to complement the characterization for both surface and subsurface sediments. Acoustic sub bottom records have also been incorporated in order to investigate the physical characteristics of certain features on the Porcupine Bank. Where available, groundtruthing information in terms of sediment samples, video footage and cores has been applied to add physical descriptors and validation to the characterization. Extensive mapping of different rock outcrops, sediment drifts, seabed features and other geological classes has been achieved using this methodology.

  13. NW-MILO Acoustic Data Collection

    Energy Technology Data Exchange (ETDEWEB)

    Matzner, Shari; Myers, Joshua R.; Maxwell, Adam R.; Jones, Mark E.

    2010-02-17

    There is an enduring requirement to improve our ability to detect potential threats and discriminate these from the legitimate commercial and recreational activity ongoing in the nearshore/littoral portion of the maritime domain. The Northwest Maritime Information and Littoral Operations (NW-MILO) Program at PNNL’s Coastal Security Institute in Sequim, Washington is establishing a methodology to detect and classify these threats - in part through developing a better understanding of acoustic signatures in a near-shore environment. The purpose of the acoustic data collection described here is to investigate the acoustic signatures of small vessels. The data is being recorded continuously, 24 hours a day, along with radar track data and imagery. The recording began in August 2008, and to date the data contains tens of thousands of signals from small vessels recorded in a variety of environmental conditions. The quantity and variety of this data collection, with the supporting imagery and radar track data, makes it particularly useful for the development of robust acoustic signature models and advanced algorithms for signal classification and information extraction. The underwater acoustic sensing system is part of a multi-modal sensing system that is operating near the mouth of Sequim Bay. Sequim Bay opens onto the Straight of Juan de Fuca, which contains part of the border between the U.S. and Canada. Table 1 lists the specific components used for the NW-MILO system. The acoustic sensor is a hydrophone permanently deployed at a mean depth of about 3 meters. In addition to a hydrophone, the other sensors in the system are a marine radar, an electro-optical (EO) camera and an infra-red (IR) camera. The radar is integrated with a vessel tracking system (VTS) that provides position, speed and heading information. The data from all the sensors is recorded and saved to a central server. The data has been validated in terms of its usability for characterizing the

  14. High transmission acoustic focusing by impedance-matched acoustic meta-surfaces

    KAUST Repository

    Al Jahdali, Rasha

    2016-01-19

    Impedance is an important issue in the design of acoustic lenses because mismatched impedance is detrimental to real focusing applications. Here, we report two designs of acoustic lenses that focus acoustic waves in water and air, respectively. They are tailored by acoustic meta-surfaces, which are rigid thin plates decorated with periodically distributed sub-wavelength slits. Their respective building blocks are constructed from the coiling-up spaces in water and the layered structures in air. Analytic analysis based on coupled-mode theory and transfer matrix reveals that the impedances of the lenses are matched to those of the background media. With these impedance-matched acoustic lenses, we demonstrate the acoustic focusing effect by finite-element simulations.

  15. High transmission acoustic focusing by impedance-matched acoustic meta-surfaces

    KAUST Repository

    Al Jahdali, Rasha; Wu, Ying

    2016-01-01

    Impedance is an important issue in the design of acoustic lenses because mismatched impedance is detrimental to real focusing applications. Here, we report two designs of acoustic lenses that focus acoustic waves in water and air, respectively. They are tailored by acoustic meta-surfaces, which are rigid thin plates decorated with periodically distributed sub-wavelength slits. Their respective building blocks are constructed from the coiling-up spaces in water and the layered structures in air. Analytic analysis based on coupled-mode theory and transfer matrix reveals that the impedances of the lenses are matched to those of the background media. With these impedance-matched acoustic lenses, we demonstrate the acoustic focusing effect by finite-element simulations.

  16. The Study of Fault Location for Front-End Electronics System

    International Nuclear Information System (INIS)

    Zhang Fan; Wang Dong; Huang Guangming; Zhou Daicui

    2009-01-01

    Since some devices on the latest developed 250 ALICE/PHOS Front-end electronics (FEE) system cards had been partly or completely damaged during lead-free soldering. To alleviate the influence on the performance of FEE system and to locate fault related FPGA accurately, we should find a method for locating fault of FEE system based on the deep study of FPGA configuration scheme. It emphasized on the problems such as JTAG configuration of multi-devices, PS configuration based on EPC series configuration devices and auto re-configuration of FPGA. The result of the massive FEE system cards testing and repairing show that that location method can accurately and quickly target the fault point related FPGA on FEE system cards. (authors)

  17. The perceptual influence of the cabin acoustics on the reproduced sound of a car audio system

    DEFF Research Database (Denmark)

    Kaplanis, Neofytos; Bech, Søren; Sakari, Tervo

    2015-01-01

    -end car audio system was performed for different physical settings of the car's cabin. A novel spatial auralization methodology was then used, and participants were asked to describe verbally the perceived acoustical characteristics of the stimuli. The elicited attributes were then analyzed following...... a previous review [Kaplanis et al., in 55th Int. Conf. Aud. Eng. Soc. (2014)] and possible links to the acoustical properties of the car cabin are discussed. [This study is a part of Marie Curie Network on Dereverberation and Reverberation of Audio, Music, and Speech. EU-FP7 under agreement ITN-GA-2012-316969.]...

  18. A comparison of partially specular radiosity and ray tracing for room acoustics modeling

    Science.gov (United States)

    Beamer, C. Walter; Muehleisen, Ralph T.

    2005-04-01

    Partially specular (PS) radiosity is an extended form of the general radiosity method. Acoustic radiosity is a form of bulk transfer of radiant acoustic energy. This bulk transfer is accomplished through a system of energy balance equations that relate the bulk energy transfer of each surface in the system to all other surfaces in the system. Until now acoustic radiosity has been limited to modeling only diffuse surface reflection. The new PS acoustic radiosity method can model all real surface types, diffuse, specular and everything in between. PS acoustic radiosity also models all real source types and distributions, not just point sources. The results of the PS acoustic radiosity method are compared to those of well known ray tracing programs. [Work supported by NSF.

  19. A Correlated Active Acoustic Leak Detection in a SFR Steam Generator

    International Nuclear Information System (INIS)

    Kim, Tae Joon; Jeong, Ji Young; Kim, Jong Man; Kim, Byung Ho; Kim, Yong Il

    2009-01-01

    The methods of acoustic leak detection are active acoustic leak detection and passive acoustic leak detection. The methods for passive acoustic leak detection are already established, but because our goal is development of passive acoustic leak detection for detecting a leakage range of small and micro leak rates, it is difficult detecting a leak in steam generator using this developed passive acoustic leak detection. Thus the acoustic leak detection system is required to be able to detect wide range of water leaks. From this view point we need to develop an active acoustic leak detection technology to be able to detect intermediate leak rates

  20. Acoustic and electromagnetic emission as a tool for crack localization

    International Nuclear Information System (INIS)

    Sedlak, P; Sikula, J; Lokajicek, T; Mori, Y

    2008-01-01

    The creation of cracks is accompanied by electric charge redistribution due to loosened chemical bounds. Electric charge on a crack wall creates dipole moments. Vibrations of crack walls produce time-dependent dipole moments and, consequently, electric and magnetic fields are generated. An electric signal is induced on metal electrodes. Simultaneously with the electromagnetic emission (EME) signal, an acoustic emission (AE) signal is generated, but due to the different velocities of propagation of both waves, the detection of the AE signal is delayed. This time delay presents the time of the wave propagation from the individual acoustic emission sensor to the crack. The defect can be located by means of these time intervals. This paper describes the localization using acoustic and electromagnetic emission signals for the two-dimensional case

  1. Acoustic and wind speed data analysis as an environmental issue

    International Nuclear Information System (INIS)

    Whitson, R.J.; MacKinnon, A.

    1995-01-01

    This paper examines how the output from a cup anemometer, used for wind speed measurement, can be recorded on magnetic tape and analysed using instrumentation normally employed to measure acoustic data. The purpose of this being to allow true simultaneous analysis of acoustic and wind speed data. NEL's NWTC (National Wind Turbine Centre) Anemometer Calibration Facility is used to compare pulsed and analogue outputs from a typical anemometer to the data obtained from a pitot/static tube for a range of different wind speeds. The usefulness of 1/24- and 1/12-octave analysis is examined and accuracy limits are derived for the 'acoustic' approach to wind speed measurement. The allowable positions for anemometer locations are also discussed with reference to currently available standards and recommended practices. (Author)

  2. Reliability testing of failed fuel location system

    International Nuclear Information System (INIS)

    Vieru, G.

    1996-01-01

    This paper presents the experimental reliability tests performed in order to prove the reliability parameters for Failed Fuel Location System (FFLS), equipment used to detect in which channel of a particular heat transport loop a fuel failure is located, and to find in which channel what particular bundle pair is failed. To do so, D20 samples from each reactor channel are sequentially monitored to detect a comparatively high level of delayed neutron activity. 15 refs, 8 figs, 2 tabs

  3. Classroom acoustics in public schools: A case study

    Science.gov (United States)

    Loro, Carmen P.; Zannin, Paulo T.

    2004-05-01

    The acoustic quality of a standard classroom (Standard 23) of the public school system in the city of Curitiba has been evaluated. This standard has a central circulation aisle with two classrooms in each side. Each room has windows to the outside and to the internal aisle. Additionally, the aisle has a 6-m-high zenithal skylight, together composing the building's main lighting and ventilation system. But, Standard 23 lacks acoustic quality of the classrooms. In order to assay this, measurements have been performed under several conditions, using the Building Acoustics System of Bruel & Kjaer. The measured reverberation time (RT) of the four classrooms for a frequency of 500 Hz was: 1.65 s (empty classroom), 1.15 s (20 students in the room), and 0.76 s (40 students). According to WHO recommendations, the ideal RT in classrooms should be around 0.6 s. DIN 18041 establishes an RT between 0.8 and 1.0 s, to allow for adequate intelligibility. Background noise in an empty room was 63.3 dB (A), above the limit established by the Brazilian standard of acoustic comfort: 40 dB (A). The reaction of students and teachers has indicated that the main source of acoustic discomfort is the noise generated by the neighboring classrooms.

  4. Controllable Solid Propulsion Combustion and Acoustic Knowledge Base Improvements

    Science.gov (United States)

    McCauley, Rachel; Fischbach, Sean; Fredrick, Robert

    2012-01-01

    Controllable solid propulsion systems have distinctive combustion and acoustic environments that require enhanced testing and analysis techniques to progress this new technology from development to production. In a hot gas valve actuating system, the movement of the pintle through the hot gas exhibits complex acoustic disturbances and flow characteristics that can amplify induced pressure loads that can damage or detonate the rocket motor. The geometry of a controllable solid propulsion gas chamber can set up unique unsteady flow which can feed acoustic oscillations patterns that require characterization. Research in this area aids in the understanding of how best to design, test, and analyze future controllable solid rocket motors using the lessons learned from past government programs as well as university research and testing. This survey paper will give the reader a better understanding of the potentially amplifying affects propagated by a controllable solid rocket motor system and the knowledge of the tools current available to address these acoustic disturbances in a preliminary design. Finally the paper will supply lessons learned from past experiences which will allow the reader to come away with understanding of what steps need to be taken when developing a controllable solid rocket propulsion system. The focus of this survey will be on testing and analysis work published by solid rocket programs and from combustion and acoustic books, conference papers, journal articles, and additionally from subject matter experts dealing currently with controllable solid rocket acoustic analysis.

  5. Vibro-acoustics

    CERN Document Server

    Nilsson, Anders

    2015-01-01

    This three-volume book gives a thorough and comprehensive presentation of vibration and acoustic theories. Different from traditional textbooks which typically deal with some aspects of either acoustic or vibration problems, it is unique of this book to combine those two correlated subjects together. Moreover, it provides fundamental analysis and mathematical descriptions for several crucial phenomena of Vibro-Acoustics which are quite useful in noise reduction, including how structures are excited, energy flows from an excitation point to a sound radiating surface, and finally how a structure radiates noise to a surrounding fluid. Many measurement results included in the text make the reading interesting and informative. Problems/questions are listed at the end of each chapter and the solutions are provided. This will help the readers to understand the topics of Vibro-Acoustics more deeply. The book should be of interest to anyone interested in sound and vibration, vehicle acoustics, ship acoustics and inter...

  6. Acoustics an introduction

    CERN Document Server

    Kuttruff, Heinrich

    2006-01-01

    This definitive textbook provides students with a comprehensive introduction to acoustics. Beginning with the basic physical ideas, Acoustics balances the fundamentals with engineering aspects, applications and electroacoustics, also covering music, speech and the properties of human hearing. The concepts of acoustics are exposed and applied in:room acousticssound insulation in buildingsnoise controlunderwater sound and ultrasoundScientifically thorough, but with mathematics kept to a minimum, Acoustics is the perfect introduction to acoustics for students at any level of mechanical, electrical or civil engineering courses and an accessible resource for architects, musicians or sound engineers requiring a technical understanding of acoustics and their applications.

  7. 46 CFR 58.60-5 - Industrial systems: Locations.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Industrial systems: Locations. 58.60-5 Section 58.60-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS Industrial Systems and Components on Mobile Offshore Drilling Units (MODU...

  8. The effect of brain lesions on sound localization in complex acoustic environments.

    Science.gov (United States)

    Zündorf, Ida C; Karnath, Hans-Otto; Lewald, Jörg

    2014-05-01

    Localizing sound sources of interest in cluttered acoustic environments--as in the 'cocktail-party' situation--is one of the most demanding challenges to the human auditory system in everyday life. In this study, stroke patients' ability to localize acoustic targets in a single-source and in a multi-source setup in the free sound field were directly compared. Subsequent voxel-based lesion-behaviour mapping analyses were computed to uncover the brain areas associated with a deficit in localization in the presence of multiple distracter sound sources rather than localization of individually presented sound sources. Analyses revealed a fundamental role of the right planum temporale in this task. The results from the left hemisphere were less straightforward, but suggested an involvement of inferior frontal and pre- and postcentral areas. These areas appear to be particularly involved in the spectrotemporal analyses crucial for effective segregation of multiple sound streams from various locations, beyond the currently known network for localization of isolated sound sources in otherwise silent surroundings.

  9. Zooplankton structure and vertical migration: Using acoustics and biomass to compare stratified and mixed fjord systems

    Science.gov (United States)

    Díaz-Astudillo, Macarena; Cáceres, Mario A.; Landaeta, Mauricio F.

    2017-09-01

    The patterns of abundance, composition, biomass and vertical migration of zooplankton in short-time scales (ADCP device mounted on the hull of a ship were used to obtain vertical profiles of current velocity data and intensity of the backscattered acoustic signal, which was used to study the migratory strategies and to relate the echo intensity with zooplankton biomass. Repeated vertical profiles of temperature, salinity and density were obtained with a CTD instrument to describe the density patterns during both experiments. Zooplankton were sampled every 3 h using a Bongo net to determine abundance, composition and biomass. Migrations were diel in the stratified station, semi-diel in the mixed station, and controlled by light in both locations, with large and significant differences in zooplankton abundance and biomass between day and night samples. No migration pattern associated with the effect of tides was found. The depth of maximum backscatter strength showed differences of approximately 30 m between stations and was deeper in the mixed station. The relation between mean volume backscattering strength (dB) computed from echo intensity and log10 of total dry weight (mg m-3) of zooplankton biomass was moderate but significant in both locations. Biomass estimated from biological samples was higher in the mixed station and determined by euphausiids. Copepods were the most abundant group in both stations. Acoustic methods were a useful technique to understand the detailed patterns of migratory strategies of zooplankton and to help estimate zooplankton biomass and abundance in the inner waters of southern Chile.

  10. Towards an Automated Acoustic Detection System for Free Ranging Elephants.

    Science.gov (United States)

    Zeppelzauer, Matthias; Hensman, Sean; Stoeger, Angela S

    The human-elephant conflict is one of the most serious conservation problems in Asia and Africa today. The involuntary confrontation of humans and elephants claims the lives of many animals and humans every year. A promising approach to alleviate this conflict is the development of an acoustic early warning system. Such a system requires the robust automated detection of elephant vocalizations under unconstrained field conditions. Today, no system exists that fulfills these requirements. In this paper, we present a method for the automated detection of elephant vocalizations that is robust to the diverse noise sources present in the field. We evaluate the method on a dataset recorded under natural field conditions to simulate a real-world scenario. The proposed method outperformed existing approaches and robustly and accurately detected elephants. It thus can form the basis for a future automated early warning system for elephants. Furthermore, the method may be a useful tool for scientists in bioacoustics for the study of wildlife recordings.

  11. Study of aerosol behaviour in an acoustic field

    International Nuclear Information System (INIS)

    Malherbe, C.

    1988-01-01

    The average size of an aerosol submitted to acoustic waves is increased. This results from coagulation of the finer particles on the larger ones. An experimental apparatus was developed in order to control the evolution of aerosol distribution in an acoustic field. Important deposition on the walls of the agglomeration chamber was observed as a consequence of the acoustically induced turbulent flow. Consequently, we experimentally evaluated the turbulent properties of the system. A granular bed submitted to an acoustic field and set downstream an agglomerator constitutes an almost absolute filter for an usually penetrating aerosol [fr

  12. Interior acoustic cloak

    OpenAIRE

    Wael Akl; A. Baz

    2014-01-01

    Acoustic cloaks have traditionally been intended to externally surround critical objects to render these objects acoustically invisible. However, in this paper, the emphasis is placed on investigating the application of the acoustic cloaks to the interior walls of acoustic cavities in an attempt to minimize the noise levels inside these cavities. In this manner, the acoustic cloaks can serve as a viable and efficient alternative to the conventional passive noise attenuation treatments which a...

  13. HYDROBS: a long-term autonomous mooring for passive acoustic monitoring

    Science.gov (United States)

    Hello, Y.; Royer, J. Y.; Yegikyan, M.

    2017-12-01

    Passive acoustics proves an effective way for monitoring the low-level seismic activity of the ocean floor and low-frequency sounds from the ocean (baleen whales, sea-state, icebergs). Networks of synchronized autonomous hydrophones have thus been commonly deployed in the world ocean to monitor large sections of mid-oceanic ridges. HYDROBS is an improved system that meet two requirements: an easy access to the data collected by the instruments together with long-term deployments - up to 4 consecutive years - reducing the need of large vessels capable of yearly mooring operations in open seas. The system has two components: a data logger, up-to-date but similar to previous systems, and three messengers, releasable on demand to collect the data. The mooring line itself is classical, with an expandable weight at the sea-bottom to maintain the mooring, an acoustic release to free the mooring line for recovery, a line adjustable to the seafloor depth, and an immerged buoy, holding the acquisition system, to maintain the sensors at a constant depth and to bring the mooring line to the surface for its recovery. The data logger is based on a low-power microprocessor, an A/D-32bit convertor sampling at 250Hz, a 10-8 real time clock and SD card storage. Lithium batteries provide 3-4 years of autonomy. Acoustic communications with the surface-ship provide control over all functionalities at deployment and a health bulletin on demand. The 3 shuttles, encapsulated in 13" glass spheres, use the same CPU board and clock as the main station. Data transfer from the data logger to the shuttles is wireless (1Mbit/s digital inductive through water). Data are duplicated once per day on shuttles N and N+1 for redundancy. Prior to their release by acoustic command, the shuttles are synchronized with the master clock. At sea-surface, shuttles (as the main unit) look for GPS time and calculate their clock drift. So, the master clock drift can be monitored over time at every shuttle release

  14. Acoustic wavefield evolution as a function of source location perturbation

    KAUST Repository

    Alkhalifah, Tariq Ali

    2010-12-01

    The wavefield is typically simulated for seismic exploration applications through solving the wave equation for a specific seismic source location. The direct relation between the form (or shape) of the wavefield and the source location can provide insights useful for velocity estimation and interpolation. As a result, I derive partial differential equations that relate changes in the wavefield shape to perturbations in the source location, especially along the Earth\\'s surface. These partial differential equations have the same structure as the wave equation with a source function that depends on the background (original source) wavefield. The similarity in form implies that we can use familiar numerical methods to solve the perturbation equations, including finite difference and downward continuation. In fact, we can use the same Green\\'s function to solve the wave equation and its source perturbations by simply incorporating source functions derived from the background field. The solutions of the perturbation equations represent the coefficients of a Taylor\\'s series type expansion of the wavefield as a function of source location. As a result, we can speed up the wavefield calculation as we approximate the wavefield shape for sources in the vicinity of the original source. The new formula introduces changes to the background wavefield only in the presence of lateral velocity variation or in general terms velocity variations in the perturbation direction. The approach is demonstrated on the smoothed Marmousi model.

  15. Acoustic Igniter, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — An acoustic igniter eliminates the need to use electrical energy to drive spark systems to initiate combustion in liquid-propellant rockets. It does not involve the...

  16. [Acoustic information in snoring noises].

    Science.gov (United States)

    Janott, C; Schuller, B; Heiser, C

    2017-02-01

    More than one third of all people snore regularly. Snoring is a common accompaniment of obstructive sleep apnea (OSA) and is often disruptive for the bed partner. This work gives an overview of the history of and state of research on acoustic analysis of snoring for classification of OSA severity, detection of obstructive events, measurement of annoyance, and identification of the sound excitation location. Based on these objectives, searches were conducted in the literature databases PubMed and IEEE Xplore. Publications dealing with the respective objectives according to title and abstract were selected from the search results. A total of 48 publications concerning the above objectives were considered. The limiting factor of many studies is the small number of subjects upon which the analyses are based. Recent research findings show promising results, such that acoustic analysis may find a place in the framework of sleep diagnostics, thus supplementing the recognized standard methods.

  17. Acoustic constituents of prosodic typology

    Science.gov (United States)

    Komatsu, Masahiko

    series of studies showed the correspondence of the source component to prosodic features. In linguistics, prosodic types have not been discussed purely in terms of acoustics; they are usually related to the function of prosody or phonological units such as phonemes. The present thesis focuses on acoustics and makes a contribution to establishing the crosslinguistic description system of prosody.

  18. Device for acoustic detection in a nuclear reactor

    International Nuclear Information System (INIS)

    Hanff, M.; Lions, N.; Peronnet, J.

    1975-01-01

    A description is given of a device which comprises a first acoustic conductor placed vertically within the coolant liquid contained in a nuclear reactor vessel and a second coaxial acoustic conductor extending to the exterior of the reactor vessel. The device essentially comprises an accelerometer assembly for detecting signals delivered by the second conductor and an amplifier which applies the detected signals to measuring instruments located outside the reactor vessel. The accelerometer comprises an amplifying pressure needle carried by the upper end of the second conductor, a piezoelectric ceramic element, a block fitted with a spring for applying the ceramic element against the needle and a preamplifier connected in series with the amplifier

  19. Ellipsoidal reflector for measuring oto-acoustic emissions

    DEFF Research Database (Denmark)

    Epp, Bastian; Pulkki, Ville; Heiskanen, Vesa

    2014-01-01

    A truncated prolate ellipsoidal reflector having the ear canal of a listener at one focal point and large- diaphragm low-noise microphone at the other focal point is proposed for free-field recordings of oto-acoustic emissions. A prototype reflector consisting of three pieces is presented, which...... enables measuring the response of the system with different truncations. The response of the system is measured with a miniature loud- speaker, and proof-of-concept measurements of oto-acoustic emissions are presented. The effect of truncation and other physical parameters to the performance of the system...

  20. Localization of short-range acoustic and seismic wideband sources: Algorithms and experiments

    Science.gov (United States)

    Stafsudd, J. Z.; Asgari, S.; Hudson, R.; Yao, K.; Taciroglu, E.

    2008-04-01

    We consider the determination of the location (source localization) of a disturbance source which emits acoustic and/or seismic signals. We devise an enhanced approximate maximum-likelihood (AML) algorithm to process data collected at acoustic sensors (microphones) belonging to an array of, non-collocated but otherwise identical, sensors. The approximate maximum-likelihood algorithm exploits the time-delay-of-arrival of acoustic signals at different sensors, and yields the source location. For processing the seismic signals, we investigate two distinct algorithms, both of which process data collected at a single measurement station comprising a triaxial accelerometer, to determine direction-of-arrival. The direction-of-arrivals determined at each sensor station are then combined using a weighted least-squares approach for source localization. The first of the direction-of-arrival estimation algorithms is based on the spectral decomposition of the covariance matrix, while the second is based on surface wave analysis. Both of the seismic source localization algorithms have their roots in seismology; and covariance matrix analysis had been successfully employed in applications where the source and the sensors (array) are typically separated by planetary distances (i.e., hundreds to thousands of kilometers). Here, we focus on very-short distances (e.g., less than one hundred meters) instead, with an outlook to applications in multi-modal surveillance, including target detection, tracking, and zone intrusion. We demonstrate the utility of the aforementioned algorithms through a series of open-field tests wherein we successfully localize wideband acoustic and/or seismic sources. We also investigate a basic strategy for fusion of results yielded by acoustic and seismic arrays.

  1. Phased Array Focusing for Acoustic Wireless Power Transfer.

    Science.gov (United States)

    Tseng, Victor Farm-Guoo; Bedair, Sarah S; Lazarus, Nathan

    2018-01-01

    Wireless power transfer (WPT) through acoustic waves can achieve higher efficiencies than inductive coupling when the distance is above several times the transducer size. This paper demonstrates the use of ultrasonic phased arrays to focus power to receivers at arbitrary locations to increase the power transfer efficiency. Using a phased array consisting of 37 elements at a distance nearly 5 times the receiver transducer diameter, a factor of 2.6 increase in efficiency was achieved when compared to a case equivalent to a single large transducer with the same peak efficiency distance. The array has a total diameter of 7 cm, and transmits through air at 40 kHz to a 1.1-cm diameter receiver, achieving a peak overall efficiency of 4% at a distance of 5 cm. By adjusting the focal distance, the efficiency can also be maintained relatively constant at distances up to 9 cm. Numerical models were developed and shown to closely match the experimental energy transfer behavior; modeling results indicate that the efficiency can be further doubled by increasing the number of elements. For comparison, an inductive WPT system was also built with the diameters of the transmitting and receiving coils equivalent to the dimensions of the transmitting ultrasonic phased array and receiver transducer, and the acoustic WPT system achieved higher efficiencies than the inductive WPT system when the transmit-to-receive distance is above 5 cm. In addition, beam angle steering was demonstrated by using a simplified seven-element 1-D array, achieving power transfer less dependent on receiver placement.

  2. A statistical characterization method for damping material properties and its application to structural-acoustic system design

    International Nuclear Information System (INIS)

    Jung, Byung C.; Lee, Doo Ho; Youn, Byeng D.; Lee, Soo Bum

    2011-01-01

    The performance of surface damping treatments may vary once the surface is exposed to a wide range of temperatures, because the performance of viscoelastic damping material is highly dependent on operational temperature. In addition, experimental data for dynamic responses of viscoelastic material are inherently random, which makes it difficult to design a robust damping layout. In this paper a statistical modeling procedure with a statistical calibration method is suggested for the variability characterization of viscoelastic damping material in constrained-layer damping structures. First, the viscoelastic material property is decomposed into two sources: (I) a random complex modulus due to operational temperature variability, and (II) experimental/model errors in the complex modulus. Next, the variability in the damping material property is obtained using the statistical calibration method by solving an unconstrained optimization problem with a likelihood function metric. Two case studies are considered to show the influence of the material variability on the acoustic performances in the structural-acoustic systems. It is shown that the variability of the damping material is propagated to that of the acoustic performances in the systems. Finally, robust and reliable damping layout designs of the two case studies are obtained through the reliability-based design optimization (RBDO) amidst severe variability in operational temperature and the damping material

  3. Panel acoustic contribution analysis.

    Science.gov (United States)

    Wu, Sean F; Natarajan, Logesh Kumar

    2013-02-01

    Formulations are derived to analyze the relative panel acoustic contributions of a vibrating structure. The essence of this analysis is to correlate the acoustic power flow from each panel to the radiated acoustic pressure at any field point. The acoustic power is obtained by integrating the normal component of the surface acoustic intensity, which is the product of the surface acoustic pressure and normal surface velocity reconstructed by using the Helmholtz equation least squares based nearfield acoustical holography, over each panel. The significance of this methodology is that it enables one to analyze and rank relative acoustic contributions of individual panels of a complex vibrating structure to acoustic radiation anywhere in the field based on a single set of the acoustic pressures measured in the near field. Moreover, this approach is valid for both interior and exterior regions. Examples of using this method to analyze and rank the relative acoustic contributions of a scaled vehicle cabin are demonstrated.

  4. World Conference on Acoustic Emission 2013

    CERN Document Server

    Wu, Zhanwen; Zhang, Junjiao

    2015-01-01

    This volume collects the papers from the 2013 World Conference on Acoustic Emission in Shanghai. The latest research and applications of Acoustic Emission (AE) are explored, with particular emphasis on detecting and processing of AE signals, development of AE instrument and testing standards, AE of materials, engineering structures and systems, including the processing of collected data and analytical techniques as well as experimental case studies.

  5. World Conference on Acoustic Emission 2015

    CERN Document Server

    Wu, Zhanwen; Zhang, Junjiao

    2017-01-01

    This volume collects the papers from the World Conference on Acoustic Emission 2015 (WCAE-2015) in Hawaii. The latest research and applications of Acoustic Emission (AE) are explored, with particular emphasis on detecting and processing of AE signals, development of AE instrument and testing standards, AE of materials, engineering structures and systems, including the processing of collected data and analytical techniques as well as experimental case studies.

  6. Investigation of bulk acoustic microwaves excited by an interdigital transducer

    Directory of Open Access Journals (Sweden)

    Reshotka O. G.

    2015-12-01

    Full Text Available Excitation of bulk and surface acoustic waves with the interdigital transducer (IDT, which is deposited on the surface of piezoelectric crystal, is widely used in the development of devices in acoustoelectronics and in the design of the microwave acousto-optic deflectors. Excitation of bulk acoustic waves by IDT in the devices on surface acoustic waves leads to the appearance of spurious signals. At the same time excitation of bulk acoustic waves with IDT from the surface of lithium niobate crystals allows creating high frequency acousto-optic deflectors, which makes possible to significantly simplify the technology of their production. Therefore, significant attention is paid to the task of excitation and distribution of bulk acoustic waves with IDT including recent times by the method of simulation of their excitation and distribution. The obtained theoretical results require experimental verification. This paper documents the visualization of acoustic beams excited with IDT from the XY-surface of lithium niobate crystals. The Bragg cells with LiNbO3 crystals coated with IDT with a different period of electrodes were manufactured for the experimental research of excitation and distribution of bulk acoustic waves. Visualization results have shown that the acoustic waves excited with IDT distribute in both the Fresnel zone and the Fraunhofer zone. The length of these zones is caused by individual elementary emitters of which consists the IDT (by their size. At the same time the far zone for IDT is located at distances much greater than the actual size of the LiNbO3 crystals. This peculiarity is not always taken into account when calculating diffraction. The achieved results can be used to design high-frequency acousto-optic devices, as well as in the development of devices based on surface acoustic waves.

  7. Acoustic emission events from sodium vapour bubble collapsing: a stochastic model

    Energy Technology Data Exchange (ETDEWEB)

    Colombino, A; Dentico, G; Pacilio, N; Papalia, B; Taglienti, S; Tosi, V; Vigo, A [Comitato Nazionale per l' Energia Nucleare, Casaccia (Italy). Centro di Studi Nucleari; Galli, C [Rome Univ. (Italy). Ist. di Matematica

    1981-01-01

    The forward Kolomogorov equation method has been applied to a zero-dimensional model which describes the time distribution of acoustic emissions from sodium vapour bubble collapsing. Processes taken into account as components for outlining the upstated phenomenon are: energy generation, energy dissipation, bubble creation, acoustic emission and energy release from bubble collapsing. Processes involve affect or are induced by a population of particles (bubbles, acoustic pulses) and pseudoparticles (energetic units). A formulation is obtained for the expected values of some stochastic indicators, i.e., factorial moments and cumulants, autocorrelation functions, waiting time distribution between contiguous events, of the time series consisting of acoustic emission pulses as detected by a suitable sensor. Preliminary, but promising, validation of the model and a sound prelude to effective boiling regime diagnosing is obtained by processing data from the out-of-pile CFNa loop in Grenoble, France. Data are collected from a piezoelectric accelerometer located nearby the circuit.

  8. Modeling ground vehicle acoustic signatures for analysis and synthesis

    International Nuclear Information System (INIS)

    Haschke, G.; Stanfield, R.

    1995-01-01

    Security and weapon systems use acoustic sensor signals to classify and identify moving ground vehicles. Developing robust signal processing algorithms for this is expensive, particularly in presence of acoustic clutter or countermeasures. This paper proposes a parametric ground vehicle acoustic signature model to aid the system designer in understanding which signature features are important, developing corresponding feature extraction algorithms and generating low-cost, high-fidelity synthetic signatures for testing. The authors have proposed computer-generated acoustic signatures of armored, tracked ground vehicles to deceive acoustic-sensored smart munitions. They have developed quantitative measures of how accurately a synthetic acoustic signature matches those produced by actual vehicles. This paper describes parameters of the model used to generate these synthetic signatures and suggests methods for extracting these parameters from signatures of valid vehicle encounters. The model incorporates wide-bandwidth and narrow- bandwidth components that are modulated in a pseudo-random fashion to mimic the time dynamics of valid vehicle signatures. Narrow- bandwidth feature extraction techniques estimate frequency, amplitude and phase information contained in a single set of narrow frequency- band harmonics. Wide-bandwidth feature extraction techniques estimate parameters of a correlated-noise-floor model. Finally, the authors propose a method of modeling the time dynamics of the harmonic amplitudes as a means adding necessary time-varying features to the narrow-bandwidth signal components. The authors present results of applying this modeling technique to acoustic signatures recorded during encounters with one armored, tracked vehicle. Similar modeling techniques can be applied to security systems

  9. Acoustically and Electrokinetically Driven Transport in Microfluidic Devices

    Science.gov (United States)

    Sayar, Ersin

    Electrokinetically driven flows are widely employed as a primary method for liquid pumping in micro-electromechanical systems. Mixing of analytes and reagents is limited in microfluidic devices due to the low Reynolds number of the flows. Acoustic excitations have recently been suggested to promote mixing in the microscale flow systems. Electrokinetic flows through straight microchannels were investigated using the Poisson-Boltzmann and Nernst-Planck models. The acoustic wave/fluid flow interactions in a microchannel were investigated via the development of two and three-dimensional dynamic predictive models for flows with field couplings of the electrical, mechanical and fluid flow quantities. The effectiveness and applicability of electrokinetic augmentation in flexural plate wave micropumps for enhanced capabilities were explored. The proposed concept can be exploited to integrate micropumps into complex microfluidic chips improving the portability of micro-total-analysis systems along with the capabilities of actively controlling acoustics and electrokinetics for micro-mixer applications. Acoustically excited flows in microchannels consisting of flexural plate wave devices and thin film resonators were considered. Compressible flow fields were considered to accommodate the acoustic excitations produced by a vibrating wall. The velocity and pressure profiles for different parameters including frequency, channel height, wave amplitude and length were investigated. Coupled electrokinetics and acoustics cases were investigated while the electric field intensity of the electrokinetic body forces and actuation frequency of acoustic excitations were varied. Multifield analysis of a piezoelectrically actuated valveless micropump was also presented. The effect of voltage and frequency on membrane deflection and flow rate were investigated. Detailed fluid/solid deformation coupled simulations of piezoelectric valveless micropump have been conducted to predict the

  10. Acoustic leak detection in nuclear power plants

    International Nuclear Information System (INIS)

    McElroy, J.W.

    1986-01-01

    For several years now, utilities have been utilizing acoustic leak detection methods as an operating tool in their nuclear power stations. The purpose for using the leak detection system at the various stations vary from safety, ALARA, improved operations, preventive maintenance, or increased plant availability. This paper describes the various acoustic techniques and their application. The techniques are divided into three categories: specific component leakage, intersystem leakage, and pipe through-wall crack leakage. The paper addresses each category in terms of motivation to monitor, method of application and operation, and benefits to be gained. Current requirements are reviewed and analyzed with respect to the acoustic techniques. The paper shows how acoustic leak detection is one of the most effective leak detection tools available. 9 figures, 1 table

  11. Testing Time and Frequency Fiber-Optic Link Transfer by Hardware Emulation of Acoustic-Band Optical Noise

    Directory of Open Access Journals (Sweden)

    Lipiński Marcin

    2016-06-01

    Full Text Available The low-frequency optical-signal phase noise induced by mechanical vibration of the base occurs in field-deployed fibers. Typical telecommunication data transfer is insensitive to this type of noise but the phenomenon may influence links dedicated to precise Time and Frequency (T&F fiber-optic transfer that exploit the idea of stabilization of phase or propagation delay of the link. To measure effectiveness of suppression of acoustic noise in such a link, a dedicated measurement setup is necessary. The setup should enable to introduce a low-frequency phase corruption to the optical signal in a controllable way. In the paper, a concept of a setup in which the mechanically induced acoustic-band optical signal phase corruption is described and its own features and measured parameters are presented. Next, the experimental measurement results of the T&F transfer TFTS-2 system’s immunity as a function of the fibre-optic length vs. the acoustic-band noise are presented. Then, the dependency of the system immunity on the location of a noise source along the link is also pointed out.

  12. Acoustic Multipurpose Cargo Transfer Bag

    Science.gov (United States)

    Baccus, Shelley

    2015-01-01

    The Logistics Reduction (LR) project within the Advanced Exploration Systems (AES) program is tasked with reducing logistical mass and repurposing logistical items. Multipurpose Cargo Transfer Bags (MCTB) are designed to be the same external volume as a regular cargo transfer bag, the common logistics carrier for the International Space Station. After use as a cargo bag, the MCTB can be unzipped and unfolded to be reused. This Acoustic MCTBs transform into acoustic blankets after the initial logistics carrying objective is complete.

  13. Acoustic wave (AW) based moisture sensor for use with corrosive gases

    Science.gov (United States)

    Pfeifer, K.B.; Frye, G.C.; Schneider, T.W.

    1996-11-05

    Moisture corrosive gas stream is measured as a function of the difference in resonant frequencies between two acoustic wave (AW) devices, each with a film which accepts at least one of the components of the gas stream. One AW is located in the gas stream while the other is located outside the gas stream but in the same thermal environment. In one embodiment, the film is a hydrophilic material such as SiO{sub 2}. In another embodiment, the SiO{sub 2} is covered with another film which is impermeable to the corrosive gas, such that the AW device in the gas stream measures only the water vapor. In yet another embodiment, the film comprises polyethylene oxide which is hydrophobic and measures only the partial pressure of the corrosive gas. Other embodiments allow for compensation of drift in the system. 8 figs.

  14. Comparing autonomous underwater vehicle (AUV) and vessel-based tracking performance for locating acoustically tagged fish

    OpenAIRE

    Eiler, John H.; Grothues, Thomas M.; Dobarro, Joseph A.; Masuda, Michele M.

    2013-01-01

    Autonomous underwater vehicles (AUV’s) are increasingly used to collect physical, chemical, and biological information in the marine environment. Recent efforts include merging AUV technology with acoustic telemetry to provide information on the distribution and movements of marine fish. We compared surface vessel and AUV tracking capabilities under rigorous conditions in coastal waters near Juneau, Alaska. Tracking surveys were conducted with a REMUS 100 AUV equipped with an integrated acous...

  15. Estimating surface acoustic impedance with the inverse method.

    Science.gov (United States)

    Piechowicz, Janusz

    2011-01-01

    Sound field parameters are predicted with numerical methods in sound control systems, in acoustic designs of building and in sound field simulations. Those methods define the acoustic properties of surfaces, such as sound absorption coefficients or acoustic impedance, to determine boundary conditions. Several in situ measurement techniques were developed; one of them uses 2 microphones to measure direct and reflected sound over a planar test surface. Another approach is used in the inverse boundary elements method, in which estimating acoustic impedance of a surface is expressed as an inverse boundary problem. The boundary values can be found from multipoint sound pressure measurements in the interior of a room. This method can be applied to arbitrarily-shaped surfaces. This investigation is part of a research programme on using inverse methods in industrial room acoustics.

  16. Springer Handbook of Acoustics

    CERN Document Server

    Rossing, Thomas D

    2007-01-01

    Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and others. The Springer Handbook of Acoustics is an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents spanning: animal acoustics including infrasound and ultrasound, environmental noise control, music and human speech and singing, physiological and psychological acoustics, architectural acoustics, physical and engineering acoustics, signal processing, medical acoustics, and ocean acoustics. This handbook reviews the most important areas of acoustics, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest rese...

  17. Possibility-based robust design optimization for the structural-acoustic system with fuzzy parameters

    Science.gov (United States)

    Yin, Hui; Yu, Dejie; Yin, Shengwen; Xia, Baizhan

    2018-03-01

    The conventional engineering optimization problems considering uncertainties are based on the probabilistic model. However, the probabilistic model may be unavailable because of the lack of sufficient objective information to construct the precise probability distribution of uncertainties. This paper proposes a possibility-based robust design optimization (PBRDO) framework for the uncertain structural-acoustic system based on the fuzzy set model, which can be constructed by expert opinions. The objective of robust design is to optimize the expectation and variability of system performance with respect to uncertainties simultaneously. In the proposed PBRDO, the entropy of the fuzzy system response is used as the variability index; the weighted sum of the entropy and expectation of the fuzzy response is used as the objective function, and the constraints are established in the possibility context. The computations for the constraints and objective function of PBRDO are a triple-loop and a double-loop nested problem, respectively, whose computational costs are considerable. To improve the computational efficiency, the target performance approach is introduced to transform the calculation of the constraints into a double-loop nested problem. To further improve the computational efficiency, a Chebyshev fuzzy method (CFM) based on the Chebyshev polynomials is proposed to estimate the objective function, and the Chebyshev interval method (CIM) is introduced to estimate the constraints, thereby the optimization problem is transformed into a single-loop one. Numerical results on a shell structural-acoustic system verify the effectiveness and feasibility of the proposed methods.

  18. Principles and effects of acoustic cavitation - A review

    Directory of Open Access Journals (Sweden)

    Corina GÂMBUŢEANU

    2013-12-01

    Full Text Available In the recent years, food industry has shown a real interest in ultrasound use because of its effect on physical, biochemical and microbial properties of food systems. In order to better understand how the acoustic cavity effects could be best applied in food industry, a review on acoustic cavitation and its effects was done. The present paper describes in detail the basic principles underlying the effects of ultrasounds on food processing applications. It also provides theoretical background on acoustic cavitation and ultrasound production method. Moreover, harnessing mechanic, optic, chemical and biological effects of acoustic cavitation in food industry were briefly highlighted.

  19. Optimal Sensor and Actuator Location for Unstable Systems

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza; Tahavori, Maryamsadat

    2013-01-01

    on the processes. Dually the problem of placing actuators on the processes is equally important. In this paper, the problem of determining optimal sensor and actuator locations for the linear systems is addressed. The problem of the sensor locations is viewed as the problem of maximizing the output energy...... generated by a given state and for the actuator locations is viewed as the problem of minimizing the input energy required to reach a given state. Such design problems occur in many applications, and therefore have been studied extensively. Unfortunately, the results in this context, which have been...

  20. Evaluation of State-of-the-Art Acoustic Feedback Cancellation Systems for Hearing Aids

    DEFF Research Database (Denmark)

    Guo, Meng; Jensen, Søren Holdt; Jensen, Jesper

    2013-01-01

    This research evaluates four state-of-the-art acoustic feedback cancellation systems in hearing aids in terms of the cancellation performance, sound quality degradation, and computational complexity. The authors compared a traditional full-band system to a system with a prediction error method...... in a full band, a subband system, a subband system with frequency shifting, and a recently proposed subband system with a novel probe noise deployment. All systems outperformed the traditional full-band system in cancellation performance, especially the subband system with probe noise is most effective...... for cancellation. However, in all cases there was a trade-off between performance and computational cost. With a 3-times increase in computation load, the probe noise based cancellation system can be realized that functions even in the most challenging feedback situation....