Science.gov

Sample records for active acoustic system

  1. Acoustic challenges of the A400M for active systems

    NASA Astrophysics Data System (ADS)

    Breitbach, Harald; Sachau, Delf; Böhme, Sten

    2006-03-01

    In some types of aircraft tonal interior noise with high sound pressure level (up to 110 dB(A)) occurs at low frequencies (f < 500 Hz). Typical examples are propeller driven aircraft, for which the excitation frequencies are given by the blade passage frequency (BPF) and its higher harmonics. The high tonal noise levels at these frequencies can occur due to the fact that the blades' profiles are only optimized in terms of aerodynamics. The acoustic properties are usually not taken into account. In order to obtain an acceptable interior noise level, and to guarantee both work-safety and comfort in the aircraft interiors, passive methods are commonly used - e.g. adding material with high damping or vibration absorbing qualities. Especially when low frequency noise has to be reduced, adding material results in a lot of unwanted additional weight. In order to avoid this extra weight, the concept of active noise reduction (ANR) and tunable vibration absorber systems (TVA), which focus on the unwanted tonal noise, are a good compromise of treating noise and the amount of additional weight in aircraft design. This paper briefly discusses two different possible methods to reduce the low frequency noise. The noise reduction of tuned vibration absorbers (TVA) mounted on the airframe are nowadays commonly used in propeller driven aircraft and can be predicted by vibroacoustic finite element calculations, which is described in this paper. In order to abide to industrial safety regulations, the noise level inside the semi closed loadmaster area (LMA) must be reduced down to a noise level, which is even 8 dB(A) below the specified cargo hold noise level. The paper describes also the phases of development of an ANR system that could be used to control the sound pressure level inside the LMA. The concept is verified by experimental investigations within a mock up of the LMA.

  2. Acoustic imaging system

    DOEpatents

    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. Active vibration and noise control of vibro-acoustic system by using PID controller

    NASA Astrophysics Data System (ADS)

    Li, Yunlong; Wang, Xiaojun; Huang, Ren; Qiu, Zhiping

    2015-07-01

    Active control simulation of the acoustic and vibration response of a vibro-acoustic cavity of an airplane based on a PID controller is presented. A full numerical vibro-acoustic model is developed by using an Eulerian model, which is a coupled model based on the finite element formulation. The reduced order model, which is used to design the closed-loop control system, is obtained by the combination of modal expansion and variable substitution. Some physical experiments are made to validate and update the full-order and the reduced-order numerical models. Optimization of the actuator placement is employed in order to get an effective closed-loop control system. For the controller design, an iterative method is used to determine the optimal parameters of the PID controller. The process is illustrated by the design of an active noise and vibration control system for a cavity structure. The numerical and experimental results show that a PID-based active control system can effectively suppress the noise inside the cavity using a sound pressure signal as the controller input. It is also possible to control the noise by suppressing the vibration of the structure using the structural displacement signal as the controller input. For an airplane cavity structure, considering the issue of space-saving, the latter is more suitable.

  4. Wireless Acoustic Measurement System

    NASA Technical Reports Server (NTRS)

    Anderson, Paul D.; Dorland, Wade D.; Jolly, Ronald L.

    2007-01-01

    A prototype wireless acoustic measurement system (WAMS) is one of two main subsystems of the Acoustic Prediction/ Measurement Tool, which comprises software, acoustic instrumentation, and electronic hardware combined to afford integrated capabilities for predicting and measuring noise emitted by rocket and jet engines. The other main subsystem is described in the article on page 8. The WAMS includes analog acoustic measurement instrumentation and analog and digital electronic circuitry combined with computer wireless local-area networking to enable (1) measurement of sound-pressure levels at multiple locations in the sound field of an engine under test and (2) recording and processing of the measurement data. At each field location, the measurements are taken by a portable unit, denoted a field station. There are ten field stations, each of which can take two channels of measurements. Each field station is equipped with two instrumentation microphones, a micro- ATX computer, a wireless network adapter, an environmental enclosure, a directional radio antenna, and a battery power supply. The environmental enclosure shields the computer from weather and from extreme acoustically induced vibrations. The power supply is based on a marine-service lead-acid storage battery that has enough capacity to support operation for as long as 10 hours. A desktop computer serves as a control server for the WAMS. The server is connected to a wireless router for communication with the field stations via a wireless local-area network that complies with wireless-network standard 802.11b of the Institute of Electrical and Electronics Engineers. The router and the wireless network adapters are controlled by use of Linux-compatible driver software. The server runs custom Linux software for synchronizing the recording of measurement data in the field stations. The software includes a module that provides an intuitive graphical user interface through which an operator at the control server

  5. Wireless Acoustic Measurement System

    NASA Technical Reports Server (NTRS)

    Anderson, Paul D.; Dorland, Wade D.

    2005-01-01

    A prototype wireless acoustic measurement system (WAMS) is one of two main subsystems of the Acoustic Prediction/Measurement Tool, which comprises software, acoustic instrumentation, and electronic hardware combined to afford integrated capabilities for predicting and measuring noise emitted by rocket and jet engines. The other main subsystem is described in "Predicting Rocket or Jet Noise in Real Time" (SSC-00215-1), which appears elsewhere in this issue of NASA Tech Briefs. The WAMS includes analog acoustic measurement instrumentation and analog and digital electronic circuitry combined with computer wireless local-area networking to enable (1) measurement of sound-pressure levels at multiple locations in the sound field of an engine under test and (2) recording and processing of the measurement data. At each field location, the measurements are taken by a portable unit, denoted a field station. There are ten field stations, each of which can take two channels of measurements. Each field station is equipped with two instrumentation microphones, a micro-ATX computer, a wireless network adapter, an environmental enclosure, a directional radio antenna, and a battery power supply. The environmental enclosure shields the computer from weather and from extreme acoustically induced vibrations. The power supply is based on a marine-service lead-acid storage battery that has enough capacity to support operation for as long as 10 hours. A desktop computer serves as a control server for the WAMS. The server is connected to a wireless router for communication with the field stations via a wireless local-area network that complies with wireless-network standard 802.11b of the Institute of Electrical and Electronics Engineers. The router and the wireless network adapters are controlled by use of Linux-compatible driver software. The server runs custom Linux software for synchronizing the recording of measurement data in the field stations. The software includes a module that

  6. Acoustic velocity meter systems

    USGS Publications Warehouse

    Laenen, Antonius

    1985-01-01

    Acoustic velocity meter (AVM) systems operate on the principles that the point-to-point upstream traveltime of an acoustic pulse is longer than the downstream traveltime and that this difference in traveltime can be accurately measured by electronic devices. An AVM system is capable of recording water velocity (and discharge) under a wide range of conditions, but some constraints apply: 1. Accuracy is reduced and performance is degraded if the acoustic path is not a continuous straight line. The path can be bent by reflection if it is too close to a stream boundary or by refraction if it passes through density gradients resulting from variations in either water temperature or salinity. For paths of less than 100 m, a temperature gradient of 0.1' per meter causes signal bending less than 0.6 meter at midchannel, and satisfactory velocity results can be obtained. Reflection from stream boundaries can cause signal cancellation if boundaries are too close to signal path. 2. Signal strength is attenuated by particles or bubbles that absorb, spread, or scatter sound. The concentration of particles or bubbles that can be tolerated is a function of the path length and frequency of the acoustic signal. 3. Changes in streamline orientation can affect system accuracy if the variability is random. 4. Errors relating to signal resolution are much larger for a single threshold detection scheme than for multiple threshold schemes. This report provides methods for computing the effect of various conditions on the accuracy of a record obtained from an AVM. The equipment must be adapted to the site. Field reconnaissance and preinstallation analysis to detect possible problems are critical for proper installation and operation of an AVM system.

  7. Active acoustics for music rehearsal rooms

    NASA Astrophysics Data System (ADS)

    Freiheit, Ronald R.

    2003-10-01

    The use of virtual acoustics has the ability to provide a new level of rehearsal experience for the musician. By integrating the signal processing of an active acoustic system (with time variant-gain before feedback) into a relatively small rehearsal room, musicians can now benefit from the experience of rehearsing in multiple acoustic environments including those of the actual performance venue in which they will perform. To effectively communicate the various acoustics environments, the musicians must be immersed in the sound field of the active acoustics without being able to discern source locations of the speakers. The system must also be cable of supporting the dynamic range of the musicians without presenting artifacts of its own such as system noise or audible distortion. An installation of such a system will be provided as a case study describing the challenges that were overcome for a successful implementation including areas such as adequate sound isolation, background noise levels and system security. The paper will also briefly discuss programming methodologies for the system. Anecdotal responses from musicians who have used the active acoustic rehearsal room and some unexpected issues will also be covered.

  8. Active control of acoustic field-of-view in a biosonar system.

    PubMed

    Yovel, Yossi; Falk, Ben; Moss, Cynthia F; Ulanovsky, Nachum

    2011-09-01

    Active-sensing systems abound in nature, but little is known about systematic strategies that are used by these systems to scan the environment. Here, we addressed this question by studying echolocating bats, animals that have the ability to point their biosonar beam to a confined region of space. We trained Egyptian fruit bats to land on a target, under conditions of varying levels of environmental complexity, and measured their echolocation and flight behavior. The bats modulated the intensity of their biosonar emissions, and the spatial region they sampled, in a task-dependant manner. We report here that Egyptian fruit bats selectively change the emission intensity and the angle between the beam axes of sequentially emitted clicks, according to the distance to the target, and depending on the level of environmental complexity. In so doing, they effectively adjusted the spatial sector sampled by a pair of clicks-the "field-of-view." We suggest that the exact point within the beam that is directed towards an object (e.g., the beam's peak, maximal slope, etc.) is influenced by three competing task demands: detection, localization, and angular scanning-where the third factor is modulated by field-of-view. Our results suggest that lingual echolocation (based on tongue clicks) is in fact much more sophisticated than previously believed. They also reveal a new parameter under active control in animal sonar-the angle between consecutive beams. Our findings suggest that acoustic scanning of space by mammals is highly flexible and modulated much more selectively than previously recognized. PMID:21931535

  9. Active micromixer using surface acoustic wave streaming

    DOEpatents

    Branch; Darren W. , Meyer; Grant D. , Craighead; Harold G.

    2011-05-17

    An active micromixer uses a surface acoustic wave, preferably a Rayleigh wave, propagating on a piezoelectric substrate to induce acoustic streaming in a fluid in a microfluidic channel. The surface acoustic wave can be generated by applying an RF excitation signal to at least one interdigital transducer on the piezoelectric substrate. The active micromixer can rapidly mix quiescent fluids or laminar streams in low Reynolds number flows. The active micromixer has no moving parts (other than the SAW transducer) and is, therefore, more reliable, less damaging to sensitive fluids, and less susceptible to fouling and channel clogging than other types of active and passive micromixers. The active micromixer is adaptable to a wide range of geometries, can be easily fabricated, and can be integrated in a microfluidic system, reducing dead volume. Finally, the active micromixer has on-demand on/off mixing capability and can be operated at low power.

  10. Guided acoustic wave inspection system

    DOEpatents

    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.

  11. Acoustic trapping of active matter

    NASA Astrophysics Data System (ADS)

    Takatori, Sho C.; de Dier, Raf; Vermant, Jan; Brady, John F.

    2016-03-01

    Confinement of living microorganisms and self-propelled particles by an external trap provides a means of analysing the motion and behaviour of active systems. Developing a tweezer with a trapping radius large compared with the swimmers' size and run length has been an experimental challenge, as standard optical traps are too weak. Here we report the novel use of an acoustic tweezer to confine self-propelled particles in two dimensions over distances large compared with the swimmers' run length. We develop a near-harmonic trap to demonstrate the crossover from weak confinement, where the probability density is Boltzmann-like, to strong confinement, where the density is peaked along the perimeter. At high concentrations the swimmers crystallize into a close-packed structure, which subsequently `explodes' as a travelling wave when the tweezer is turned off. The swimmers' confined motion provides a measurement of the swim pressure, a unique mechanical pressure exerted by self-propelled bodies.

  12. Acoustic trapping of active matter.

    PubMed

    Takatori, Sho C; De Dier, Raf; Vermant, Jan; Brady, John F

    2016-01-01

    Confinement of living microorganisms and self-propelled particles by an external trap provides a means of analysing the motion and behaviour of active systems. Developing a tweezer with a trapping radius large compared with the swimmers' size and run length has been an experimental challenge, as standard optical traps are too weak. Here we report the novel use of an acoustic tweezer to confine self-propelled particles in two dimensions over distances large compared with the swimmers' run length. We develop a near-harmonic trap to demonstrate the crossover from weak confinement, where the probability density is Boltzmann-like, to strong confinement, where the density is peaked along the perimeter. At high concentrations the swimmers crystallize into a close-packed structure, which subsequently 'explodes' as a travelling wave when the tweezer is turned off. The swimmers' confined motion provides a measurement of the swim pressure, a unique mechanical pressure exerted by self-propelled bodies. PMID:26961816

  13. Truck acoustic data analyzer system

    DOEpatents

    Haynes, Howard D.; Akerman, Alfred; Ayers, Curtis W.

    2006-07-04

    A passive vehicle acoustic data analyzer system having at least one microphone disposed in the acoustic field of a moving vehicle and a computer in electronic communication the microphone(s). The computer detects and measures the frequency shift in the acoustic signature emitted by the vehicle as it approaches and passes the microphone(s). The acoustic signature of a truck driving by a microphone can provide enough information to estimate the truck speed in miles-per-hour (mph), engine speed in rotations-per-minute (RPM), turbocharger speed in RPM, and vehicle weight.

  14. Acoustic Suppression Systems and Related Methods

    NASA Technical Reports Server (NTRS)

    Kolaini, Ali R. (Inventor); Kern, Dennis L. (Inventor)

    2013-01-01

    An acoustic suppression system for absorbing and/or scattering acoustic energy comprising a plurality of acoustic targets in a containment is described, the acoustic targets configured to have resonance frequencies allowing the targets to be excited by incoming acoustic waves, the resonance frequencies being adjustable to suppress acoustic energy in a set frequency range. Methods for fabricating and implementing the acoustic suppression system are also provided.

  15. Acoustic trapping of active matter

    PubMed Central

    Takatori, Sho C.; De Dier, Raf; Vermant, Jan; Brady, John F.

    2016-01-01

    Confinement of living microorganisms and self-propelled particles by an external trap provides a means of analysing the motion and behaviour of active systems. Developing a tweezer with a trapping radius large compared with the swimmers' size and run length has been an experimental challenge, as standard optical traps are too weak. Here we report the novel use of an acoustic tweezer to confine self-propelled particles in two dimensions over distances large compared with the swimmers' run length. We develop a near-harmonic trap to demonstrate the crossover from weak confinement, where the probability density is Boltzmann-like, to strong confinement, where the density is peaked along the perimeter. At high concentrations the swimmers crystallize into a close-packed structure, which subsequently ‘explodes' as a travelling wave when the tweezer is turned off. The swimmers' confined motion provides a measurement of the swim pressure, a unique mechanical pressure exerted by self-propelled bodies. PMID:26961816

  16. Acoustic emission monitoring system

    DOEpatents

    Romrell, Delwin M.

    1977-07-05

    Methods and apparatus for identifying the source location of acoustic emissions generated within an acoustically conductive medium. A plurality of acoustic receivers are communicably coupled to the surface of the medium at a corresponding number of spaced locations. The differences in the reception time of the respective sensors in response to a given acoustic event are measured among various sensor combinations prescribed by the monitoring mode employed. Acoustic reception response encountered subsequent to the reception by a predetermined number of the prescribed sensor combinations are inhibited from being communicated to the processing circuitry, while the time measurements obtained from the prescribed sensor combinations are translated into a position measurement representative of the location on the surface most proximate the source of the emission. The apparatus is programmable to function in six separate and five distinct operating modes employing either two, three or four sensory locations. In its preferred arrangement the apparatus of this invention will re-initiate a monitoring interval if the predetermined number of sensors do not respond to a particular emission within a given time period.

  17. Intelligent Engine Systems: Acoustics

    NASA Technical Reports Server (NTRS)

    Wojno, John; Martens, Steve; Simpson, Benjamin

    2008-01-01

    An extensive study of new fan exhaust nozzle technologies was performed. Three new uniform chevron nozzles were designed, based on extensive CFD analysis. Two new azimuthally varying variants were defined. All five were tested, along with two existing nozzles, on a representative model-scale, medium BPR exhaust nozzle. Substantial acoustic benefits were obtained from the uniform chevron nozzle designs, the best benefit being provided by an existing design. However, one of the azimuthally varying nozzle designs exhibited even better performance than any of the uniform chevron nozzles. In addition to the fan chevron nozzles, a new technology was demonstrated, using devices that enhance mixing when applied to an exhaust nozzle. The acoustic benefits from these devices applied to medium BPR nozzles were similar, and in some cases superior to, those obtained from conventional uniform chevron nozzles. However, none of the low noise technologies provided equivalent acoustic benefits on a model-scale high BPR exhaust nozzle, similar to current large commercial applications. New technologies must be identified to improve the acoustics of state-of-the-art high BPR jet engines.

  18. Acoustics Research of Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Gao, Ximing; Houston, Janice D.

    2014-01-01

    The liftoff phase induces some of the highest acoustic loading over a broad frequency for a launch vehicle. These external acoustic environments are used in the prediction of the internal vibration responses of the vehicle and components. Thus, predicting these liftoff acoustic environments is critical to the design requirements of any launch vehicle but there are challenges. Present liftoff vehicle acoustic environment prediction methods utilize stationary data from previously conducted hold-down tests; i.e. static firings conducted in the 1960's, to generate 1/3 octave band Sound Pressure Level (SPL) spectra. These data sets are used to predict the liftoff acoustic environments for launch vehicles. To facilitate the accuracy and quality of acoustic loading, predictions at liftoff for future launch vehicles such as the Space Launch System (SLS), non-stationary flight data from the Ares I-X were processed in PC-Signal in two forms which included a simulated hold-down phase and the entire launch phase. In conjunction, the Prediction of Acoustic Vehicle Environments (PAVE) program was developed in MATLAB to allow for efficient predictions of sound pressure levels (SPLs) as a function of station number along the vehicle using semiempirical methods. This consisted, initially, of generating the Dimensionless Spectrum Function (DSF) and Dimensionless Source Location (DSL) curves from the Ares I-X flight data. These are then used in the MATLAB program to generate the 1/3 octave band SPL spectra. Concluding results show major differences in SPLs between the hold-down test data and the processed Ares IX flight data making the Ares I-X flight data more practical for future vehicle acoustic environment predictions.

  19. Acoustic counter-sniper system

    NASA Astrophysics Data System (ADS)

    Duckworth, Gregory L.; Gilbert, Douglas C.; Barger, James E.

    1997-02-01

    BBN has developed, tested, and fielded pre-production versions of a versatile acoustics-based counter-sniper system. This system was developed by BBN for the DARPA Tactical Technology Office to provide a low cost and accurate sniper detection and localization system. The system uses observations of the shock wave from supersonic bullets to estimate the bullet trajectory, Mach number, and caliber. If muzzle blast observations are also available from unsilenced weapons, the exact sniper location along the trajectory is also estimated. A newly developed and very accurate model of the bullet ballistics and acoustic radiation is used which includes bullet deceleration. This allows the use of very flexible acoustic sensor types and placements, since the system can model the bullet's flight, and hence the acoustic observations, over a wide area very accurately. System sensor configurations can be as simple as two small four element tetrahedral microphone arrays on either side of the area to be protected, or six omnidirectional microphones spread over the area to be monitored. Increased performance can be obtained by expanding the sensor field in size or density, and the system software is easily reconfigured to accommodate this at deployment time. Sensor nodes can be added using wireless network telemetry or hardwired cables to the command node processing and display computer. The system has been field tested in three government sponsored tests in both rural and simulated urban environments at the Camp Pendleton MOUT facility. Performance was characterized during these tests for various shot geometries and bullet speeds and calibers.

  20. Ecological Insights from Pelagic Habitats Acquired Using Active Acoustic Techniques.

    PubMed

    Benoit-Bird, Kelly J; Lawson, Gareth L

    2016-01-01

    Marine pelagic ecosystems present fascinating opportunities for ecological investigation but pose important methodological challenges for sampling. Active acoustic techniques involve producing sound and receiving signals from organisms and other water column sources, offering the benefit of high spatial and temporal resolution and, via integration into different platforms, the ability to make measurements spanning a range of spatial and temporal scales. As a consequence, a variety of questions concerning the ecology of pelagic systems lend themselves to active acoustics, ranging from organism-level investigations and physiological responses to the environment to ecosystem-level studies and climate. As technologies and data analysis methods have matured, the use of acoustics in ecological studies has grown rapidly. We explore the continued role of active acoustics in addressing questions concerning life in the ocean, highlight creative applications to key ecological themes ranging from physiology and behavior to biogeography and climate, and discuss emerging avenues where acoustics can help determine how pelagic ecosystems function. PMID:26515810

  1. Ecological Insights from Pelagic Habitats Acquired Using Active Acoustic Techniques

    NASA Astrophysics Data System (ADS)

    Benoit-Bird, Kelly J.; Lawson, Gareth L.

    2016-01-01

    Marine pelagic ecosystems present fascinating opportunities for ecological investigation but pose important methodological challenges for sampling. Active acoustic techniques involve producing sound and receiving signals from organisms and other water column sources, offering the benefit of high spatial and temporal resolution and, via integration into different platforms, the ability to make measurements spanning a range of spatial and temporal scales. As a consequence, a variety of questions concerning the ecology of pelagic systems lend themselves to active acoustics, ranging from organism-level investigations and physiological responses to the environment to ecosystem-level studies and climate. As technologies and data analysis methods have matured, the use of acoustics in ecological studies has grown rapidly. We explore the continued role of active acoustics in addressing questions concerning life in the ocean, highlight creative applications to key ecological themes ranging from physiology and behavior to biogeography and climate, and discuss emerging avenues where acoustics can help determine how pelagic ecosystems function.

  2. A state feedback electro-acoustic transducer for active control of acoustic impedance

    NASA Astrophysics Data System (ADS)

    Samejima, Toshiya

    2003-03-01

    In this paper, a new control system in which the acoustic impedance of an electro-acoustic transducer diaphragm can be actively varied by modifying design parameters is presented and its effectiveness is theoretically investigated. The proposed control system is based on a state-space description of the control system derived from an electrical equivalent circuit of an electro-acoustic transducer to which a differentiating circuit is connected, and is designed using modern control theory. The optimal quadratic regulator is used in the control system design, with its quadratic performance index formulated for producing desired acoustic impedance. Computer simulations indicate that the acoustic impedance of the diaphragm can be significantly varied over a wide frequency range that includes the range below the resonance frequency of the electro-acoustic transducer. A computer model of the proposed control system is used to illustrate its application to semi-active noise control in a duct. It is demonstrated that the proposed control system provides substantial reductions in the noise radiating from the outlet of the duct, both in the stiffness control range and in the mass control range.

  3. Active acoustical impedance using distributed electrodynamical transducers.

    PubMed

    Collet, M; David, P; Berthillier, M

    2009-02-01

    New miniaturization and integration capabilities available from emerging microelectromechanical system (MEMS) technology will allow silicon-based artificial skins involving thousands of elementary actuators to be developed in the near future. SMART structures combining large arrays of elementary motion pixels coated with macroscopic components are thus being studied so that fundamental properties such as shape, stiffness, and even reflectivity of light and sound could be dynamically adjusted. This paper investigates the acoustic impedance capabilities of a set of distributed transducers connected with a suitable controlling strategy. Research in this domain aims at designing integrated active interfaces with a desired acoustical impedance for reaching an appropriate global acoustical behavior. This generic problem is intrinsically connected with the control of multiphysical systems based on partial differential equations (PDEs) and with the notion of multiscaled physics when a dense array of electromechanical systems (or MEMS) is considered. By using specific techniques based on PDE control theory, a simple boundary control equation capable of annihilating the wave reflections has been built. The obtained strategy is also discretized as a low order time-space operator for experimental implementation by using a dense network of interlaced microphones and loudspeakers. The resulting quasicollocated architecture guarantees robustness and stability margins. This paper aims at showing how a well controlled semidistributed active skin can substantially modify the sound transmissibility or reflectivity of the corresponding homogeneous passive interface. In Sec. IV, numerical and experimental results demonstrate the capabilities of such a method for controlling sound propagation in ducts. Finally, in Sec. V, an energy-based comparison with a classical open-loop strategy underlines the system's efficiency. PMID:19206865

  4. Design of a programmable active acoustics metamaterial

    NASA Astrophysics Data System (ADS)

    Smoker, Jason J.

    Metamaterials are artificial materials engineered to provide properties which may not be readily available in nature. The development of such class of materials constitutes a new area of research that has grown significantly over the past decade. Acoustic metamaterials, specifically, are even more novel than their electromagnetic counterparts arising only in the latter half of the decade. Acoustic metamaterials provide a new tool in controlling the propagation of pressure waves. However, physical design and frequency tuning, is still a large obstacle when creating a new acoustic metamaterial. This dissertation describes active and programmable design for acoustic metamaterials which allows the same basic physical design principles to be used for a variety of application. With cloaking technology being of a great interest to the US Navy, the proposed design approach would enable the development of a metamaterial with spatially changing effective parameters while retaining a uniform physical design features. The effective parameters would be controlled by tuning smart actuators embedded inside the metamaterial structure. Since this design is based on dynamic effective parameters that can be electrically controlled, material property ranges of several orders of magnitude could potentially be achieved without changing any physical parameters. With such unique capabilities, physically realizable acoustic cloaks can be achieved and objects treated with these active metamaterials can become acoustically invisible.

  5. Acoustic system for material transport

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Trinh, E. H.; Wang, T. G.; Elleman, D. D.; Jacobi, N. (Inventor)

    1983-01-01

    An object within a chamber is acoustically moved by applying wavelengths of different modes to the chamber to move the object between pressure wells formed by the modes. In one system, the object is placed in one end of the chamber while a resonant mode, applied along the length of the chamber, produces a pressure well at the location. The frequency is then switched to a second mode that produces a pressure well at the center of the chamber, to draw the object. When the object reaches the second pressure well and is still traveling towards the second end of the chamber, the acoustic frequency is again shifted to a third mode (which may equal the first model) that has a pressure well in the second end portion of the chamber, to draw the object. A heat source may be located near the second end of the chamber to heat the sample, and after the sample is heated it can be cooled by moving it in a corresponding manner back to the first end of the chamber. The transducers for levitating and moving the object may be all located at the cool first end of the chamber.

  6. Advanced Technology Development for Active Acoustic Liners

    NASA Technical Reports Server (NTRS)

    Sheplak, Mark; Cattafesta, Louis N., III; Nishida, Toshikazu; Kurdila, Andrew J.

    2001-01-01

    Objectives include: (1) Develop electro-mechanical/acoustic models of a Helmholtz resonator possessing a compliant diaphragm coupled to a piezoelectric device; (2) Design and fabricate the energy reclamation module and active Helmholtz resonator; (3) Develop and build appropriate energy reclamation/storage circuit; (4) Develop and fabricate appropriate piezoelectric shunt circuit to tune the compliance of the active Helmholtz resonator via a variable capacitor; (5) Quantify energy reclamation module efficiency in a grazing-flow plane wave tube possessing known acoustic energy input; and (6) Quantify actively tuned Helmholtz resonator performance in grazing-flow plane wave tube for a white-noise input

  7. A signal processing approach for enhanced Acoustic Emission data analysis in high activity systems: Application to organic matrix composites

    NASA Astrophysics Data System (ADS)

    Kharrat, M.; Ramasso, E.; Placet, V.; Boubakar, M. L.

    2016-03-01

    Structural elements made of Organic Matrix Composites (OMC) under complex loading may suffer from high Acoustic Emission (AE) activity caused by the emergence of different emission sources at high rates with high noise level, which finally engender continuous emissions. The detection of hits in this situation becomes a challenge particularly during fatigue tests. This work suggests an approach based on the Discrete Wavelet Transform (DWT) denoising applied on signal segments. A particular attention is paid to the adjustment of the denoising parameters based on pencil lead breaks and their influence on the quality of the denoised AE signals. The validation of the proposed approach is performed on a ring-shaped Carbon Fiber Reinforced Plastics (CFRP) under in-service-like conditions involving continuous emissions with superimposed damage-related transients. It is demonstrated that errors in hit detection are greatly reduced leading to a better identification of the natural damage scenario based on AE signals.

  8. Active acoustical impedance using distributed electrodynamic transducers

    NASA Astrophysics Data System (ADS)

    Collet, M.; Berthillier, M.; David, P.

    2006-03-01

    New miniaturization and integration capabilities available from the emerging MEMS technology will allow silicon-based artificial skins involving thousands of elementary actuators to be developed in the near future. SMART structures combining large arrays of elementary motion pixels coated with macroscopic components are thus being studied so that fundamental properties such as shape, stiffness, color, and even reflectivity of light and sound could be dynamically adjusted. This paper investigates acoustic impedance capabilities of a set of distributed transducers connected with suitable controlling laws. Basically, we search to design an integrated electro-mechanical system which presents a global behavior with appropriate acoustical characteristics. This problem is intrinsically connected with the control of multi physical system based on PDE and with the notion of multi-scaled physics when we dispose MEMS devices. By using specific techniques based on partial differential equation control theory, we have first build a simple boundary control equation able to annihilate wave reflection. The obtained control strategies can also be discretized to be implemented like a zero or first order spatial operator. Thus, we can use quasi-collocated transducers and their well-known poles-zeros interlacing property to guarantee robust stability. This paper aims at showing in a first part how a well controlled semi-distributed active skin can substantially modify transmissibility or reflectivity of the corresponding homogeneous wall. In a second part numerical and experimental results underline the capabilities of the method. Finally efficiency of such a device is compared theoretically with those obtained by classical x-filtered LMS strategy.

  9. Acoustically induced structural fatigue of piping systems

    SciTech Connect

    Eisinger, F.L.; Francis, J.T.

    1999-11-01

    Piping systems handling high-pressure and high-velocity steam and various process and hydrocarbon gases through a pressure-reducing device can produce severe acoustic vibration and metal fatigue in the system. It has been previously shown that the acoustic fatigue of the piping system is governed by the relationship between fluid pressure drop and downstream Mach number, and the dimensionless pipe diameter/wall thickness geometry parameter. In this paper, the devised relationship is extended to cover acoustic fatigue considerations of medium and smaller-diameter piping systems.

  10. Acoustically-driven microfluidic systems

    SciTech Connect

    Wang, A W; Benett, W J; Tarte, L R

    2000-06-23

    We have demonstrated a non-contact method of concentrating and mixing particles in a plastic microfluidic chamber employing acoustic radiation pressure. A flaw cell package has also been designed that integrates liquid sample interconnects, electrical contacts and a removable sample chamber. Experiments were performed on 1, 3, 6, and 10 {micro}m polystyrene beads. Increased antibody binding to a solid-phase substrate was observed in the presence of acoustic mixing due to improve mass transport.

  11. Acoustics Research of Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Gao, Ximing; Houston, Janice

    2014-01-01

    The liftoff phase induces high acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are used in the prediction of the internal vibration responses of the vehicle and components. Present liftoff vehicle acoustic environment prediction methods utilize stationary data from previously conducted hold-down tests to generate 1/3 octave band Sound Pressure Level (SPL) spectra. In an effort to update the accuracy and quality of liftoff acoustic loading predictions, non-stationary flight data from the Ares I-X were processed in PC-Signal in two flight phases: simulated hold-down and liftoff. In conjunction, the Prediction of Acoustic Vehicle Environments (PAVE) program was developed in MATLAB to allow for efficient predictions of sound pressure levels (SPLs) as a function of station number along the vehicle using semi-empirical methods. This consisted of generating the Dimensionless Spectrum Function (DSF) and Dimensionless Source Location (DSL) curves from the Ares I-X flight data. These are then used in the MATLAB program to generate the 1/3 octave band SPL spectra. Concluding results show major differences in SPLs between the hold-down test data and the processed Ares I-X flight data making the Ares I-X flight data more practical for future vehicle acoustic environment predictions.

  12. Copper vapor laser acoustic thermometry system

    DOEpatents

    Galkowski, Joseph J.

    1987-01-01

    A copper vapor laser (CVL) acoustic thermometry system is disclosed. The invention couples an acoustic pulse a predetermined distance into a laser tube by means of a transducer and an alumina rod such that an echo pulse is returned along the alumina rod to the point of entry. The time differential between the point of entry of the acoustic pulse into the laser tube and the exit of the echo pulse is related to the temperature at the predetermined distance within the laser tube. This information is processed and can provide an accurate indication of the average temperature within the laser tube.

  13. Acoustic Test Characterization of Melamine Foam for Usage in NASA's Payload Fairing Acoustic Attenuation Systems

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Anne M.; McNelis, Mark E.

    2014-01-01

    The external acoustic liftoff levels predicted for NASA's future heavy lift launch vehicles are expected to be significantly higher than the environment created by today's commercial launch vehicles. This creates a need to develop an improved acoustic attenuation system for future NASA payload fairings. NASA Glenn Research Center initiated an acoustic test series to characterize the acoustic performance of melamine foam, with and without various acoustic enhancements. This testing was denoted as NEMFAT, which stands for NESC Enhanced Melamine Foam Acoustic Test, and is the subject of this paper. Both absorption and transmission loss testing of numerous foam configurations were performed at the Riverbank Acoustical Laboratory in July 2013. The NEMFAT test data provides an initial acoustic characterization and database of melamine foam for NASA. Because of its acoustic performance and lighter mass relative to fiberglass blankets, melamine foam is being strongly considered for use in the acoustic attenuation systems of NASA's future launch vehicles.

  14. Acoustics

    NASA Astrophysics Data System (ADS)

    The acoustics research activities of the DLR fluid-mechanics department (Forschungsbereich Stroemungsmechanik) during 1988 are surveyed and illustrated with extensive diagrams, drawings, graphs, and photographs. Particular attention is given to studies of helicopter rotor noise (high-speed impulsive noise, blade/vortex interaction noise, and main/tail-rotor interaction noise), propeller noise (temperature, angle-of-attack, and nonuniform-flow effects), noise certification, and industrial acoustics (road-vehicle flow noise and airport noise-control installations).

  15. Acoustic design of the QCSEE propulsion systems

    NASA Technical Reports Server (NTRS)

    Loeffler, I. J.; Smith, E. B.; Sowers, H. D.

    1976-01-01

    Acoustic design features and techniques employed in the Quiet Clean Short-Haul Experimental Engine (QCSEE) Program are described. The role of jet/flap noise in selecting the engine fan pressure ratio for powered lift propulsion systems is discussed. The QCSEE acoustic design features include a hybrid inlet (near-sonic throat velocity with acoustic treatment); low fan and core pressure ratios; low fan tip speeds; gear-driven fans; high and low frequency stacked core noise treatment; multiple-thickness treatment; bulk absorber treatment; and treatment on the stator vanes. The QCSEE designs represent and anticipated acoustic technology improvement of 12 to 16 PNdb relative to the noise levels of the low-noise engines used on current wide-body commercial jet transport aircraft.

  16. Acoustic vs VHF Lightning Location Systems

    NASA Astrophysics Data System (ADS)

    Arechiga, R. O.; Lapierre, J. L.; Stock, M.; Erives, H.; Edens, H. E.; Stringer, A.; Rison, W.; Thomas, R. J.

    2013-12-01

    A single acoustic array can determine the 3-D location of lightning sources by using time of arrival differences arriving at the microphones and ranging techniques. The range is obtained from the time difference between the electromagnetic emission (detected by the acoustic data logger) and the acoustic signal produced by lightning. Audio frequency acoustic location systems are sensitive to the gas dynamic expansion of portions of a rapidly heating lightning channel, and so acoustic signatures are produced by a wide variety of different lightning discharge processes including: return strokes, K changes, M components, leader stepping and more. Infrasonic frequency range acoustic sensors are also sensitive to gas dynamic expansion, and in addition are also sensitive to processes which are electro-static in nature. RF location systems such as the Lightning Mapping Array (LMA) and the Continuous Sampling Broadband VHF Digital Interferometer (DITF) from New Mexico Tech (NMT) produce high quality maps of lightning discharges; however, they are sensitive to breakdown processes only and can not locate sources originating in already well conducting channels. During the summer of 2013 an acoustic audio-range array and an infrasound array were co-located with the NMT DITF in the Magdalena mountains of central New Mexico, where an LMA is also operating. The audio-range acoustic array consists of custom-designed GPS-synced data loggers with a 50 kHz sampling rate and audio range omnidirectional dynamic microphones. The infrasound array uses GPS time-synced data logger and custom-designed broadband microphones with flat response in the band of 0.01 to 500 Hz. The DITF uses flat plate dE/dt antennas bandpass filtered to 20 to 80 MHz, providing 2D maps of lightning emissions with very high (sub-microsecond) timing resolution. Both acoustic and interferometric arrays of antennas determine location of sources by coherently comparing the signals arriving at the antennas (or

  17. Acoustic Doppler discharge-measurement system

    USGS Publications Warehouse

    Simpson, Michael R.; Oltmann, Richard N.

    1990-01-01

    A discharge-measurement system that uses a vessel-mounted acoustic Doppler current profiler has been developed and tested by the U.S. Geological Survey. Discharge measurements using the system require a fraction of the time needed for conventional current-meter discharge measurements and do not require shore-based navigational aids or tag lines for positioning the vessel.

  18. Active Acoustic Monitoring of Aquatic Life.

    PubMed

    Stein, Peter J; Edson, Patrick

    2016-01-01

    Active acoustic monitoring (AAM) can be used to study the behavioral response of marine life and to mitigate harm during high-danger anthropogenic activities. This has been done in fish studies for many decades, and there are now case studies in which AAM has been used for marine mammal monitoring as well. This includes monitoring where the ranges, AAM frequency of operation, and species are such that the AAM operation is completely outside the hearing range of the animals. However, it also includes AAM operations within the hearing range of marine life, although this does not necessarily that imply AAM is not a suitable tool. It is just not always possible to have a sufficient detection and tracking range and operate at a frequency outside the marine life hearing range. Likely, the best and most important application of AAM is when the anthropogenic activity to be conducted is temporary and presents a clear danger to aquatic life. PMID:26611075

  19. Acoustic microscope surface inspection system and method

    DOEpatents

    Khuri-Yakub, Butrus T.; Parent, Philippe; Reinholdtsen, Paul A.

    1991-01-01

    An acoustic microscope surface inspection system and method in which pulses of high frequency electrical energy are applied to a transducer which forms and focuses acoustic energy onto a selected location on the surface of an object and receives energy from the location and generates electrical pulses. The phase of the high frequency electrical signal pulses are stepped with respected to the phase of a reference signal at said location. An output signal is generated which is indicative of the surface of said selected location. The object is scanned to provide output signals representative of the surface at a plurality of surface locations.

  20. Acoustic microscope surface inspection system and method

    DOEpatents

    Khuri-Yakub, B.T.; Parent, P.; Reinholdtsen, P.A.

    1991-02-26

    An acoustic microscope surface inspection system and method are described in which pulses of high frequency electrical energy are applied to a transducer which forms and focuses acoustic energy onto a selected location on the surface of an object and receives energy from the location and generates electrical pulses. The phase of the high frequency electrical signal pulses are stepped with respect to the phase of a reference signal at said location. An output signal is generated which is indicative of the surface of said selected location. The object is scanned to provide output signals representative of the surface at a plurality of surface locations. 7 figures.

  1. A synthetic aperture acoustic prototype system

    NASA Astrophysics Data System (ADS)

    Luke, Robert H.; Bishop, Steven S.; Chan, Aaron M.; Gugino, Peter M.; Donzelli, Thomas P.; Soumekh, Mehrdad

    2015-05-01

    A novel quasi-monostatic system operating in a side-scan synthetic aperture acoustic (SAA) imaging mode is presented. This research project's objectives are to explore the military utility of outdoor continuous sound imaging of roadside foliage and target detection. The acoustic imaging method has several military relevant advantages such as being immune to RF jamming, superior spatial resolution as compared to 0.8-2.4 GHz ground penetrating radar (GPR), capable of standoff side and forward-looking scanning, and relatively low cost, weight and size when compared to GPR technologies. The prototype system's broadband 2-17 kHz LFM chirp transceiver is mounted on a manned all-terrain vehicle. Targets are positioned within the acoustic main beam at slant ranges of two to seven meters and on surfaces such as dirt, grass, gravel and weathered asphalt and with an intervening metallic chain link fence. Acoustic image reconstructions and signature plots result in means for literal interpretation and quantifiable analyses.

  2. Mean Flow Augmented Acoustics in Rocket Systems

    NASA Technical Reports Server (NTRS)

    Fischbach, Sean

    2014-01-01

    Combustion instability 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. Recent advances in energy based modeling of combustion instabilities require accurate determination of acoustic frequencies and mode shapes. Of particular interest is the acoustic mean flow interactions within the converging section of a rocket nozzle, where gradients of pressure, density, and velocity become large. The expulsion of unsteady energy through the nozzle of a rocket is identified as the predominate source of acoustic damping for most rocket systems. 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 present study aims to implement the French model within the COMSOL Multiphysiscs framework and analyzes one of the author's presented test cases.

  3. Acoustic imaging systems (for robotic object acquisition)

    NASA Astrophysics Data System (ADS)

    Richardson, J. M.; Martin, J. F.; Marsh, K. A.; Schoenwald, J. S.

    1985-03-01

    The long-term objective of the effort is to establish successful approaches for 3D acoustic imaging of dense solid objects in air to provide the information required for acquisition and manipulation of these objects by a robotic system. The objective of this first year's work was to achieve and demonstrate the determination of the external geometry (shape) of such objects with a fixed sparse array of sensors, without the aid of geometrical models or extensive training procedures. Conventional approaches for acoustic imaging fall into two basic categories. The first category is used exclusively for dense solid objects. It involves echo-ranging from a large number of sensor positions, achieved either through the use of a larger array of transducers or through extensive physical scanning of a small array. This approach determines the distance to specular reflection points from each sensor position; with suitable processing an image can be inferred. The second category uses the full acoustic waveforms to provide an image, but is strictly applicable only to weak inhomogeneities. The most familiar example is medical imaging of the soft tissue portions of the body where the range of acoustic impedance is relatively small.

  4. Chromospheric Acoustic Oscillations in Active Flaring Regions

    NASA Astrophysics Data System (ADS)

    Monsue, T.; Hill, F.; Stassun, K.

    2014-12-01

    Chromospheric p-mode oscillations are studied in Hα to obtain helioseismic information regarding the local structural conditions around highly magnetic regions such as sunspots. Solar flares commonly occur in active regions where these sunspots exist therefore boosting the p-mode power. In our current study of analyzing p-modes in the chromosphere we study the time evolution of acoustic p-mode oscillation data taken from the Global Oscillation Network Group (GONG) Hα, and investigate the p-modes across the frequency band (1 < ν < 8.33 mHz). This study entails three active regions directly over sunspots, with accompanying flaring activity from two solar flares, occurring on June 13th and July 12th, 2012. Our analysis utilizes time series data to create Fourier power spectra of individual pixels spatially resolved around the flare region, to study the frequency bands. We then study how the frequency distribution evolves temporally by constructing a Power Map Movie (PMM) of the regions. From these PMMs we can take a survey of the chromospheric oscillations for each frequency band. We found that the intensity of the flare has an effect on the behavior of the p-modes within different frequency bands. The suppression of power was observed in dark anomalous structures within the PMMs and in other regions there was an observed boost in power due to flaring activity.

  5. Acoustic Aspects of Active-Twist Rotor Control

    NASA Technical Reports Server (NTRS)

    Booth, Earl R., Jr.; Wilbur, Matthew L.

    2002-01-01

    The use of an Active Twist Rotor system to provide both vibration reduction and performance enhancement has been explored in recent analytical and experimental studies. Effects of active-twist control on rotor noise, however, had not been determined. During a recent wind tunnel test of an active-twist rotor system, a set of acoustic measurements were obtained to assess the effects of active-twist control on noise produced by the rotor, especially blade-vortex interaction (BVI) noise. It was found that for rotor operating conditions where BVI noise is dominant, active-twist control provided a reduction in BVI noise level. This BVI noise reduction was almost, but not quite, as large as that obtained in a similar test using HHC. However, vibration levels were usually adversely affected at operating conditions favoring minimum BVI noise. Conversely, operating conditions favoring minimum vibration levels affected BVI noise levels, but not always adversely.

  6. Acoustical pipe lagging systems design and performance

    SciTech Connect

    Stevens, R.D.; Chapnik, B.V.; Howe, B.

    1998-10-30

    HGC Engineering was retained by the PRC International at the American Gas Association, to undertake a study of acoustical pipe lagging systems. The study included gathering input from PRCI member companies regarding their concerns and their established material specifications for lagging systems; conducting a comprehensive acoustical measurement program; using the measured results in conjunction with computer modeling to identify optimal lagging configurations; and developing material specifications for several standardized lagging systems for use by PRCI member companies. For all the lagging configurations, the measurement and modeling results showed amplification of sound at frequencies less than about 315 Hz. This result is a well known phenomenon, widely discussed the published acoustical literature, which means that pipe lagging is only effective for controlling higher frequencies noise (above about 500 Hz). Fortunately, in many gas piping applications, it is this higher frequency range that is of concern. The measurement and modeling results further showed that the high frequency performance of a lagging system is dependent primarily on having sufficient jacket mass and insulation thickness. The performance can be improved using an intermediate mass loaded barrier layer.

  7. Computational dynamics of acoustically driven microsphere systems

    NASA Astrophysics Data System (ADS)

    Glosser, Connor; Piermarocchi, Carlo; Li, Jie; Dault, Dan; Shanker, B.

    2016-01-01

    We propose a computational framework for the self-consistent dynamics of a microsphere system driven by a pulsed acoustic field in an ideal fluid. Our framework combines a molecular dynamics integrator describing the dynamics of the microsphere system with a time-dependent integral equation solver for the acoustic field that makes use of fields represented as surface expansions in spherical harmonic basis functions. The presented approach allows us to describe the interparticle interaction induced by the field as well as the dynamics of trapping in counter-propagating acoustic pulses. The integral equation formulation leads to equations of motion for the microspheres describing the effect of nondissipative drag forces. We show (1) that the field-induced interactions between the microspheres give rise to effective dipolar interactions, with effective dipoles defined by their velocities and (2) that the dominant effect of an ultrasound pulse through a cloud of microspheres gives rise mainly to a translation of the system, though we also observe both expansion and contraction of the cloud determined by the initial system geometry.

  8. Computational dynamics of acoustically driven microsphere systems.

    PubMed

    Glosser, Connor; Piermarocchi, Carlo; Li, Jie; Dault, Dan; Shanker, B

    2016-01-01

    We propose a computational framework for the self-consistent dynamics of a microsphere system driven by a pulsed acoustic field in an ideal fluid. Our framework combines a molecular dynamics integrator describing the dynamics of the microsphere system with a time-dependent integral equation solver for the acoustic field that makes use of fields represented as surface expansions in spherical harmonic basis functions. The presented approach allows us to describe the interparticle interaction induced by the field as well as the dynamics of trapping in counter-propagating acoustic pulses. The integral equation formulation leads to equations of motion for the microspheres describing the effect of nondissipative drag forces. We show (1) that the field-induced interactions between the microspheres give rise to effective dipolar interactions, with effective dipoles defined by their velocities and (2) that the dominant effect of an ultrasound pulse through a cloud of microspheres gives rise mainly to a translation of the system, though we also observe both expansion and contraction of the cloud determined by the initial system geometry. PMID:26871188

  9. Acoustics

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

    The acoustics environment in space operations is important to maintain at manageable levels so that the crewperson can remain safe, functional, effective, and reasonably comfortable. High acoustic levels can produce temporary or permanent hearing loss, or cause other physiological symptoms such as auditory pain, headaches, discomfort, strain in the vocal cords, or fatigue. Noise is defined as undesirable sound. Excessive noise may result in psychological effects such as irritability, inability to concentrate, decrease in productivity, annoyance, errors in judgment, and distraction. A noisy environment can also result in the inability to sleep, or sleep well. Elevated noise levels can affect the ability to communicate, understand what is being said, hear what is going on in the environment, degrade crew performance and operations, and create habitability concerns. Superfluous noise emissions can also create the inability to hear alarms or other important auditory cues such as an equipment malfunctioning. Recent space flight experience, evaluations of the requirements in crew habitable areas, and lessons learned (Goodman 2003; Allen and Goodman 2003; Pilkinton 2003; Grosveld et al. 2003) show the importance of maintaining an acceptable acoustics environment. This is best accomplished by having a high-quality set of limits/requirements early in the program, the "designing in" of acoustics in the development of hardware and systems, and by monitoring, testing and verifying the levels to ensure that they are acceptable.

  10. Mean Flow Augmented Acoustics in Rocket Systems

    NASA Technical Reports Server (NTRS)

    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

  11. System for Multiplexing Acoustic Emission (AE) Instrumentation

    NASA Technical Reports Server (NTRS)

    Prosser, William H. (Inventor); Perey, Daniel F. (Inventor); Gorman, Michael R. (Inventor); Scales, Edgar F. (Inventor)

    2003-01-01

    An acoustic monitoring device has at least two acoustic sensors with a triggering mechanism and a multiplexing circuit. After the occurrence of a triggering event at a sensor, the multiplexing circuit allows a recording component to record acoustic emissions at adjacent sensors. The acoustic monitoring device is attached to a solid medium to detect the occurrence of damage.

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

    NASA Technical Reports Server (NTRS)

    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. Artificial Swimmers Propelled by Acoustically Activated Flagella.

    PubMed

    Ahmed, Daniel; Baasch, Thierry; Jang, Bumjin; Pane, Salvador; Dual, Jürg; Nelson, Bradley J

    2016-08-10

    Recent studies have garnered considerable interest in the field of propulsion to maneuver micro- and nanosized objects. Acoustics provide an alternate and attractive method to generate propulsion. To date, most acoustic-based swimmers do not use structural resonances, and their motion is determined by a combination of bulk acoustic streaming and a standing-wave field. The resultant field is intrinsically dependent on the boundaries of their resonating chambers. Though acoustic based propulsion is appealing in biological contexts, existing swimmers are less efficient, especially when operating in vivo, since no predictable standing-wave can be established in a human body. Here we describe a new class of nanoswimmer propelled by the small-amplitude oscillation of a flagellum-like flexible tail in standing and, more importantly, in traveling acoustic waves. The artificial nanoswimmer, fabricated by multistep electrodeposition techniques, compromises a rigid bimetallic head and a flexible tail. During acoustic excitation of the nanoswimmer the tail structure oscillates, which leads to a large amplitude propulsion in traveling waves. FEM simulation results show that the structural resonances lead to high propulsive forces. PMID:27459382

  14. Acoustic emission monitoring of composite containment systems

    NASA Astrophysics Data System (ADS)

    Maguire, John R.

    2011-07-01

    This paper considers two different types of composite containment system, and two different types of acoustic emission (AE) monitoring approach. The first system is a composite reinforced pressure vessel (CRPV) which is monitored both during construction and in-service using a broadband modal acoustic emission (MAE) technique. The second system is a membrane cargo containment system which is monitored using both a global as well as a local AE technique. For the CRPV, the damage assessment is concerned mainly with the integrity of the composite outer layer at the construction stage, and possible fatigue cracking of the inner steel liner at the in-service stage. For the membrane tank, the damage assessment is concerned with locating and quantifying any abnormal porosities that might develop in-service. By comparing and contrasting the different types of structural system and different monitoring approaches inferences are drawn as to what role AE monitoring could take in the damage assessment of other types of composite containment system. (Detailed technical data have not been included, due to client confidentiality constraints.)

  15. Speaker verification system using acoustic data and non-acoustic data

    DOEpatents

    Gable, Todd J.; Ng, Lawrence C.; Holzrichter, John F.; Burnett, Greg C.

    2006-03-21

    A method and system for speech characterization. One embodiment includes a method for speaker verification which includes collecting data from a speaker, wherein the data comprises acoustic data and non-acoustic data. The data is used to generate a template that includes a first set of "template" parameters. The method further includes receiving a real-time identity claim from a claimant, and using acoustic data and non-acoustic data from the identity claim to generate a second set of parameters. The method further includes comparing the first set of parameters to the set of parameters to determine whether the claimant is the speaker. The first set of parameters and the second set of parameters include at least one purely non-acoustic parameter, including a non-acoustic glottal shape parameter derived from averaging multiple glottal cycle waveforms.

  16. Active control of acoustic pressure fields using smart material technologies

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Smith, R. C.

    1993-01-01

    An overview describing the use of piezoceramic patches in reducing noise in a structural acoustics setting is presented. The passive and active contributions due to patches which are bonded to an Euler-Bernoulli beam or thin shell are briefly discussed and the results are incorporated into a 2-D structural acoustics model. In this model, an exterior noise source causes structural vibrations which in turn lead to interior noise as a result of nonlinear fluid/structure coupling mechanism. Interior sound pressure levels are reduced via patches bonded to the flexible boundary (a beam in this case) which generate pure bending moments when an out-of-phase voltage is applied. Well-posedness results for the infinite dimensional system are discussed and a Galerkin scheme for approximating the system dynamics is outlined. Control is implemented by using linear quadratic regulator (LQR) optimal control theory to calculate gains for the linearized system and then feeding these gains back into the nonlinear system of interest. The effectiveness of this strategy for this problem is illustrated in an example.

  17. Miniature acoustic guidance system for endotracheal tubes

    NASA Astrophysics Data System (ADS)

    Juan, Eduardo J.

    Ensuring that the distal end of an endotracheal tube is properly located within the trachea, and that the tube is not obstructed by mucous deposition, is a major clinical concern in patients that require mechanical ventilation. A novel acoustic system was developed to allow for the continuous monitoring of endotracheal tube position and patency. A miniature sound source and two sensing microphones are placed in-line between the ventilator hose and the proximal end of the endotracheal tube. Reflections of an acoustic pulse from the endotracheal tube lumen and the airways are digitally analyzed to estimate the location and degree of obstruction, as well as the position of the distal end of the tube in the airway. The system was evaluated through computer simulations, in vitro studies, and in a rabbit model. The system noninvasively estimated tube position in vivo to within roughly 4.5 mm, and differentiated between proper tracheal, and erroneous bronchial or esophageal intubation in all cases. In addition, the system estimated the area and location of lumen obstructions in vitro to within 14% and 3.5 mm, respectively. These findings indicate that this miniature technology could improve the quality of care provided to the ventilated adult and infant.

  18. Acoustic Flow Monitor System - User Manual

    USGS Publications Warehouse

    LaHusen, Richard

    2005-01-01

    INTRODUCTION The Acoustic Flow Monitor (AFM) is a portable system that was designed by the U.S. Geological Survey Cascades Volcano Observatory to detect and monitor debris flows associated with volcanoes. It has been successfully used internationally as part of real-time warning systems in valleys threatened by such flows (Brantley, 1990; Marcial and others, 1996; Lavigne and others, 2000). The AFM system has also been proven to be an effective tool for monitoring some non-volcanic debris flows. This manual is intended to serve as a basic guide for the installation, testing, and maintenance of AFM systems. An overview of how the system works, as well as instructions for installation and guidelines for testing, is included. Interpretation of data is not covered in this manual; rather, the user should refer to the references provided for published examples of AFM data.

  19. A Summary Comparison of Active Acoustic Detections and Visual Observations of Marine Mammals in the Canadian Beaufort Sea.

    PubMed

    Pyć, Cynthia D; Geoffroy, Maxime; Knudsen, Frank R

    2016-01-01

    Fisheries sonar was used to determine the applicability of active acoustic monitoring (AAM) for marine mammal detection in the Canadian Beaufort Sea. During 170 h of simultaneous observation by marine mammal observers and active acoustic observation, 119 Balaena mysticetus (bowheads) and 4 Delphinapterus leucas (belugas) were visually sighted, while 59 acoustic signals of bowheads were detected by AAM operators. Observations and detection of seals were also recorded. Comparative results indicate that commercially available active acoustic systems can detect seals at distances up to 500 m and large baleen whales at distances up to 2 km. PMID:26611045

  20. Smart acoustic emission system for wireless monitoring of concrete structures

    NASA Astrophysics Data System (ADS)

    Yoon, Dong-Jin; Kim, Young-Gil; Kim, Chi-Yeop; Seo, Dae-Cheol

    2008-03-01

    Acoustic emission (AE) has emerged as a powerful nondestructive tool to detect preexisting defects or to characterize failure mechanisms. Recently, this technique or this kind of principle, that is an in-situ monitoring of inside damages of materials or structures, becomes increasingly popular for monitoring the integrity of large structures. Concrete is one of the most widely used materials for constructing civil structures. In the nondestructive evaluation point of view, a lot of AE signals are generated in concrete structures under loading whether the crack development is active or not. Also, it was required to find a symptom of damage propagation before catastrophic failure through a continuous monitoring. Therefore we have done a practical study in this work to fabricate compact wireless AE sensor and to develop diagnosis system. First, this study aims to identify the differences of AE event patterns caused by both real damage sources and the other normal sources. Secondly, it was focused to develop acoustic emission diagnosis system for assessing the deterioration of concrete structures such as a bridge, dame, building slab, tunnel etc. Thirdly, the wireless acoustic emission system was developed for the application of monitoring concrete structures. From the previous laboratory study such as AE event patterns analysis under various loading conditions, we confirmed that AE analysis provided a promising approach for estimating the condition of damage and distress in concrete structures. In this work, the algorithm for determining the damage status of concrete structures was developed and typical criteria for decision making was also suggested. For the future application of wireless monitoring, a low energy consumable, compact, and robust wireless acoustic emission sensor module was developed and applied to the concrete beam for performance test. Finally, based on the self-developed diagnosis algorithm and compact wireless AE sensor, new AE system for practical

  1. Acoustic systems for the measurement of streamflow

    USGS Publications Warehouse

    Laenen, Antonius; Smith, Winchell

    1982-01-01

    Very little information is available concerning acoustic velocity meter (AVM) operation, performance, and limitations. This report provides a better understanding about the application of AVM instrumentation to streamflow measurment. Operational U.S. Geological Survey systems have proven that AVM equipment is accurate and dependable. AVM equipment has no practical upper limit of measureable velocity if sonic transducers are securely placed and adequately protected, and will measure velocitites as low as 0.1 meter per second which is normally less than the threshold level for mechanical or head-loss meters. In some situations the performance of AVM equipment may be degraded by multipath interference, signal bending, signal attenuation, and variable streamline orientation. Smaller, less-expensive, more conveniently operable microprocessor equipment is now available which should increase use of AVM systems in streamflow applications. (USGS)

  2. Acoustic and Thermal Testing of an Integrated Multilayer Insulation and Broad Area Cooling Shield System

    NASA Technical Reports Server (NTRS)

    Wood, Jessica J.; Foster, Lee W.

    2013-01-01

    A Multilayer Insulation (MLI) and Broad Area Cooling (BAC) shield thermal control system shows promise for long-duration storage of cryogenic propellant. The NASA Cryogenic Propellant Storage and Transfer (CPST) project is investigating the thermal and structural performance of this tank-applied integrated system. The MLI/BAC Shield Acoustic and Thermal Test was performed to evaluate the MLI/BAC shield's structural performance by subjecting it to worst-case launch acoustic loads. Identical thermal tests using Liquid Nitrogen (LN2) were performed before and after the acoustic test. The data from these tests was compared to determine if any degradation occurred in the thermal performance of the system as a result of exposure to the acoustic loads. The thermal test series consisted of two primary components: a passive boil-off test to evaluate the MLI performance and an active cooling test to evaluate the integrated MLI/BAC shield system with chilled vapor circulating through the BAC shield tubes. The acoustic test used loads closely matching the worst-case envelope of all launch vehicles currently under consideration for CPST. Acoustic test results yielded reasonable responses for the given load. The thermal test matrix was completed prior to the acoustic test and successfully repeated after the acoustic test. Data was compared and yielded near identical results, indicating that the MLI/BAC shield configuration tested in this series is an option for structurally implementing this thermal control system concept.

  3. Two women with multiple disabilities sharing an acoustic orientation system and traveling together to indoor destinations.

    PubMed

    Lancioni, G E; Mantini, M

    1998-12-01

    This study assessed whether two women with total blindness and profound intellectual disability could share an acoustic orientation system and travel together simultaneously to common indoor destinations to perform occupational and vocational activities. The orientation system provided acoustic cues which indicated the direction to the destinations. Analysis of data indicated that the women were successful in sharing the system and could reach the destinations independently. PMID:10052076

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Electret Acoustic Transducer Array For Computerized Ultrasound Risk Evaluation System

    DOEpatents

    Moore, Thomas L.; Fisher, Karl A.

    2005-08-09

    An electret-based acoustic transducer array is provided and may be used in a system for examining tissue. The acoustic transducer array is formed with a substrate that has a multiple distinct cells formed therein. Within each of the distinct cells is positioned an acoustic transducing element formed of an electret material. A conductive membrane is formed over the distinct cells and may be flexible.

  6. Electromechanical transducer for acoustic telemetry system

    DOEpatents

    Drumheller, Douglas S.

    1993-01-01

    An improved electromechanical transducer is provided for use in an acoustic telemetry system. The transducer of this invention comprises a stack of ferroelectric ceramic disks interleaved with a plurality of spaced electrodes which are used to electrically pole the ceramic disks. The ceramic stack is housed in a metal tubular drill collar segment. The electrodes are preferably alternatively connected to ground potential and driving potential. This alternating connection of electrodes to ground and driving potential subjects each disk to an equal electric field; and the direction of the field alternates to match the alternating direction of polarization of the ceramic disks. Preferably, a thin metal foil is sandwiched between electrodes to facilitate the electrical connection. Alternatively, a thicker metal spacer plate is selectively used in place of the metal foil in order to promote thermal cooling of the ceramic stack.

  7. Extreme low frequency acoustic measurement system

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    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.

  8. Electromechanical transducer for acoustic telemetry system

    DOEpatents

    Drumheller, D.S.

    1993-06-22

    An improved electromechanical transducer is provided for use in an acoustic telemetry system. The transducer of this invention comprises a stack of ferroelectric ceramic disks interleaved with a plurality of spaced electrodes which are used to electrically pole the ceramic disks. The ceramic stack is housed in a metal tubular drill collar segment. The electrodes are preferably alternatively connected to ground potential and driving potential. This alternating connection of electrodes to ground and driving potential subjects each disk to an equal electric field; and the direction of the field alternates to match the alternating direction of polarization of the ceramic disks. Preferably, a thin metal foil is sandwiched between electrodes to facilitate the electrical connection. Alternatively, a thicker metal spacer plate is selectively used in place of the metal foil in order to promote thermal cooling of the ceramic stack.

  9. Multivariable feedback active structural acoustic control using adaptive piezoelectric sensoriactuators.

    PubMed

    Vipperman, J S; Clark, R L

    1999-01-01

    An experimental implementation of a multivariable feedback active structural acoustic control system is demonstrated on a piezostructure plate with pinned boundary conditions. Four adaptive piezoelectric sensoriactuators provide an array of truly colocated actuator/sensor pairs to be used as control transducers. Radiation filters are developed based on the self- and mutual-radiation efficiencies of the structure and are included into the performance cost of an H2 control law which minimizes total radiated sound power. In the cost function, control effort is balanced with reductions in radiated sound power. A similarity transform which produces generalized velocity states that are required as inputs to the radiation filters is presented. Up to 15 dB of attenuation in radiated sound power was observed at the resonant frequencies of the piezostructure. PMID:9921654

  10. Acoustical Evaluation of Carbonized and Activated Cotton Nonwovens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The process of manufacturing a carbonized and activated nonwoven made by cotton fiber was investigated in this paper. The study was focused on the acoustic application and nonwoven composites with cotton nonwoven as a base layer and glass fiber nonwoven, cotton nonwoven, and carbonized and activated...

  11. Acoustic systems for the measurement of streamflow

    USGS Publications Warehouse

    Laenen, Antonius; Smith, Winchell

    1983-01-01

    The acoustic velocity meter (AVM), also referred to as an ultrasonic flowmeter, has been an operational tool for the measurement of streamflow since 1965. Very little information is available concerning AVM operation, performance, and limitations. The purpose of this report is to consolidate information in such a manner as to provide a better understanding about the application of this instrumentation to streamflow measurement. AVM instrumentation is highly accurate and nonmechanical. Most commercial AVM systems that measure streamflow use the time-of-travel method to determine a velocity between two points. The systems operate on the principle that point-to-point upstream travel-time of sound is longer than the downstream travel-time, and this difference can be monitored and measured accurately by electronics. AVM equipment has no practical upper limit of measurable velocity if sonic transducers are securely placed and adequately protected. AVM systems used in streamflow measurement generally operate with a resolution of ?0.01 meter per second but this is dependent on system frequency, path length, and signal attenuation. In some applications the performance of AVM equipment may be degraded by multipath interference, signal bending, signal attenuation, and variable streamline orientation. Presently used minicomputer systems, although expensive to purchase and maintain, perform well. Increased use of AVM systems probably will be realized as smaller, less expensive, and more conveniently operable microprocessor-based systems become readily available. Available AVM equipment should be capable of flow measurement in a wide variety of situations heretofore untried. New signal-detection techniques and communication linkages can provide additional flexibility to the systems so that operation is possible in more river and estuary situations.

  12. Activating Molecules, Ions, and Solid Particles with Acoustic Cavitation

    PubMed Central

    Pflieger, Rachel; Chave, Tony; Virot, Matthieu; Nikitenko, Sergey I.

    2014-01-01

    The chemical and physical effects of ultrasound arise not from a direct interaction of molecules with sound waves, but rather from the acoustic cavitation: the nucleation, growth, and implosive collapse of microbubbles in liquids submitted to power ultrasound. The violent implosion of bubbles leads to the formation of chemically reactive species and to the emission of light, named sonoluminescence. In this manuscript, we describe the techniques allowing study of extreme intrabubble conditions and chemical reactivity of acoustic cavitation in solutions. The analysis of sonoluminescence spectra of water sparged with noble gases provides evidence for nonequilibrium plasma formation. The photons and the "hot" particles generated by cavitation bubbles enable to excite the non-volatile species in solutions increasing their chemical reactivity. For example the mechanism of ultrabright sonoluminescence of uranyl ions in acidic solutions varies with uranium concentration: sonophotoluminescence dominates in diluted solutions, and collisional excitation contributes at higher uranium concentration. Secondary sonochemical products may arise from chemically active species that are formed inside the bubble, but then diffuse into the liquid phase and react with solution precursors to form a variety of products. For instance, the sonochemical reduction of Pt(IV) in pure water provides an innovative synthetic route for monodispersed nanoparticles of metallic platinum without any templates or capping agents. Many studies reveal the advantages of ultrasound to activate the divided solids. In general, the mechanical effects of ultrasound strongly contribute in heterogeneous systems in addition to chemical effects. In particular, the sonolysis of PuO2 powder in pure water yields stable colloids of plutonium due to both effects. PMID:24747272

  13. Optimization of a Biometric System Based on Acoustic Images

    PubMed Central

    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

  14. Optimization of a biometric system based on acoustic images.

    PubMed

    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. Acoustical Evaluation of Carbonized and Activated Cotton Nonwovens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An activated carbon fiber nonwoven (ACF) was manufactured from cotton nonowoven fabric. For the ACF acoustical application, a nonwoven composite of ACF with cotton nonwoven as a base layer was developed. Also produced were the composites of the cotton nonwoven base layer with a layer of glass fiber ...

  16. Field installation of an acoustic slug-detection system

    SciTech Connect

    Dhulesia, H.; Bernicot, M.; Romanet, T.

    1997-02-01

    A pipeline operating in the slug flow regime creates high fluctuations in gas and liquid flow rates at the outlet. The detection of slugs and the estimation of their length and velocity are necessary to minimize the upsets in the operation of downstream process facilities. A new method based on the acoustic principle has been developed by Total and Syminex with two variants--passive and active. The passive method gives the slug length and velocity, whereas the active method also gives the fluid density. The prototype of this system has been installed permanently on a 20-in. multiphase pipeline in Argentina. As this system detects the slugs and determines their characteristics approximately 2 minutes before they arrive at the first-stage separator, the operators take appropriate action in the case of arrival of an excessively long slug and, thus, avoid possible shutdowns. At a later stage, an automatic adjustment of the process control valves will be realized.

  17. A survey on acoustic signature recognition and classification techniques for persistent surveillance systems

    NASA Astrophysics Data System (ADS)

    Shirkhodaie, Amir; Alkilani, Amjad

    2012-06-01

    Application of acoustic sensors in Persistent Surveillance Systems (PSS) has received considerable attention over the last two decades because they can be rapidly deployed and have low cost. Conventional utilization of acoustic sensors in PSS spans a wide range of applications including: vehicle classification, target tracking, activity understanding, speech recognition, shooter detection, etc. This paper presents a current survey of physics-based acoustic signature classification techniques for outdoor sounds recognition and understanding. Particularly, this paper focuses on taxonomy and ontology of acoustic signatures resulted from group activities. The taxonomy and supportive ontology considered include: humanvehicle, human-objects, and human-human interactions. This paper, in particular, exploits applicability of several spectral analysis techniques as a means to maximize likelihood of correct acoustic source detection, recognition, and discrimination. Spectral analysis techniques based on Fast Fourier Transform, Discrete Wavelet Transform, and Short Time Fourier Transform are considered for extraction of features from acoustic sources. In addition, comprehensive overviews of most current research activities related to scope of this work are presented with their applications. Furthermore, future potential direction of research in this area is discussed for improvement of acoustic signature recognition and classification technology suitable for PSS applications.

  18. Non-reciprocal and highly nonlinear active acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    Popa, Bogdan-Ioan; Cummer, Steven A.

    2014-02-01

    Unidirectional devices that pass acoustic energy in only one direction have numerous applications and, consequently, have recently received significant attention. However, for most practical applications that require unidirectionality at audio and low frequencies, subwavelength implementations capable of the necessary time-reversal symmetry breaking remain elusive. Here we describe a design approach based on metamaterial techniques that provides highly subwavelength and strongly non-reciprocal devices. We demonstrate this approach by designing and experimentally characterizing a non-reciprocal active acoustic metamaterial unit cell composed of a single piezoelectric membrane augmented by a nonlinear electronic circuit, and sandwiched between Helmholtz cavities tuned to different frequencies. The design is thinner than a tenth of a wavelength, yet it has an isolation factor of >10 dB. The design method generates relatively broadband unidirectional devices and is a good candidate for numerous acoustic applications.

  19. Non-reciprocal and highly nonlinear active acoustic metamaterials.

    PubMed

    Popa, Bogdan-Ioan; Cummer, Steven A

    2014-01-01

    Unidirectional devices that pass acoustic energy in only one direction have numerous applications and, consequently, have recently received significant attention. However, for most practical applications that require unidirectionality at audio and low frequencies, subwavelength implementations capable of the necessary time-reversal symmetry breaking remain elusive. Here we describe a design approach based on metamaterial techniques that provides highly subwavelength and strongly non-reciprocal devices. We demonstrate this approach by designing and experimentally characterizing a non-reciprocal active acoustic metamaterial unit cell composed of a single piezoelectric membrane augmented by a nonlinear electronic circuit, and sandwiched between Helmholtz cavities tuned to different frequencies. The design is thinner than a tenth of a wavelength, yet it has an isolation factor of >10 dB. The design method generates relatively broadband unidirectional devices and is a good candidate for numerous acoustic applications. PMID:24572771

  20. Acoustic gaze adjustments during active target selection in echolocating porpoises.

    PubMed

    Wisniewska, Danuta Maria; Johnson, Mark; Beedholm, Kristian; Wahlberg, Magnus; Madsen, Peter Teglberg

    2012-12-15

    Visually dominant animals use gaze adjustments to organize perceptual inputs for cognitive processing. Thereby they manage the massive sensory load from complex and noisy scenes. Echolocation, as an active sensory system, may provide more opportunities to control such information flow by adjusting the properties of the sound source. However, most studies of toothed whale echolocation have involved stationed animals in static auditory scenes for which dynamic information control is unnecessary. To mimic conditions in the wild, we designed an experiment with captive, free-swimming harbor porpoises tasked with discriminating between two hydrophone-equipped targets and closing in on the selected target; this allowed us to gain insight into how porpoises adjust their acoustic gaze in a multi-target dynamic scene. By means of synchronized cameras, an acoustic tag and on-target hydrophone recordings we demonstrate that porpoises employ both beam direction control and range-dependent changes in output levels and pulse intervals to accommodate their changing spatial relationship with objects of immediate interest. We further show that, when switching attention to another target, porpoises can set their depth of gaze accurately for the new target location. In combination, these observations imply that porpoises exert precise vocal-motor control that is tied to spatial perception akin to visual accommodation. Finally, we demonstrate that at short target ranges porpoises narrow their depth of gaze dramatically by adjusting their output so as to focus on a single target. This suggests that echolocating porpoises switch from a deliberative mode of sensorimotor operation to a reactive mode when they are close to a target. PMID:23175527

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

    NASA Technical Reports Server (NTRS)

    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.

  2. Structural sensing of interior sound for active control of noise in structural-acoustic cavities.

    PubMed

    Bagha, Ashok K; Modak, S V

    2015-07-01

    This paper proposes a method for structural sensing of acoustic potential energy for active control of noise in a structural-acoustic cavity. The sensing strategy aims at global control and works with a fewer number of sensors. It is based on the established concept of radiation modes and hence does not add too many states to the order of the system. Acoustic potential energy is sensed using a combination of a Kalman filter and a frequency weighting filter with the structural response measurements as the inputs. The use of Kalman filter also makes the system robust against measurement noise. The formulation of the strategy is presented using finite element models of the system including that of sensors and actuators so that it can be easily applied to practical systems. The sensing strategy is numerically evaluated in the framework of Linear Quadratic Gaussian based feedback control of interior noise in a rectangular box cavity with a flexible plate with single and multiple pairs of piezoelectric sensor-actuator patches when broadband disturbances act on the plate. The performance is compared with an "acoustic filter" that models the complete transfer function from the structure to the acoustic domain. The sensing performance is also compared with a direct estimation strategy. PMID:26233001

  3. Aeroelastic-Acoustics Simulation of Flight Systems

    NASA Technical Reports Server (NTRS)

    Gupta, kajal K.; Choi, S.; Ibrahim, A.

    2009-01-01

    This paper describes the details of a numerical finite element (FE) based analysis procedure and a resulting code for the simulation of the acoustics phenomenon arising from aeroelastic interactions. Both CFD and structural simulations are based on FE discretization employing unstructured grids. The sound pressure level (SPL) on structural surfaces is calculated from the root mean square (RMS) of the unsteady pressure and the acoustic wave frequencies are computed from a fast Fourier transform (FFT) of the unsteady pressure distribution as a function of time. The resulting tool proves to be unique as it is designed to analyze complex practical problems, involving large scale computations, in a routine fashion.

  4. Investigation of reverberation synthesized by electro-acoustic enhancement systems, from a subjective and physical acoustic standpoint

    NASA Astrophysics Data System (ADS)

    Shimizu, Yasushi

    2002-05-01

    Current electro-acoustic enhancement technology enables wide control over concert hall acoustics. The goal of sound field synthesis in anechoic space is to reconstruct a specific sound field. However, applying acoustic enhancement technology to existing reverberant spaces is a less developed research direction. This presentation demonstrates a methodology of electro-acoustic enhancement using regenerative reverberation through SAAF (spatially averaged acoustic feedback), an acceptable variation of RT and SPL in enhanced acoustical conditions. That was presented by YAMAHA Acoustic Research Laboratories. SAAF technology can flatten amplitude peaks at the howling frequency of acoustical feedback loops by using time variant finite impulse response filters. Therefore it enables regeneration of reverberated sound by wide band feedback in frequency without coloration. This system has been applied to ``negative absorption control'' and loudness equalization of under-balcony seats in current concert halls, to optimize concert hall acoustics electronically instead of architecturally. Adjusted reverberation time in enhanced condition should be between 1.5 and 2.0 times higher than the natural RT (ex. RTon/Rtoff=1.8). The SPL increases about 1 dB to 3 dB based on measured results of more than 30 performing halls integrated with acoustic enhancement system in Japan. Examples of the major Japanese concert halls with acoustic enhancement systems are presented.

  5. Field-Deployable Acoustic Digital Systems for Noise Measurement

    NASA Technical Reports Server (NTRS)

    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.

  6. Statistical Analysis of Acoustic Wave Parameters Near Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Rabello-Soares, M. Cristina; Bogart, Richard S.; Scherrer, Philip H.

    2016-08-01

    In order to quantify the influence of magnetic fields on acoustic mode parameters and flows in and around active regions, we analyze the differences in the parameters in magnetically quiet regions nearby an active region (which we call “nearby regions”), compared with those of quiet regions at the same disk locations for which there are no neighboring active regions. We also compare the mode parameters in active regions with those in comparably located quiet regions. Our analysis is based on ring-diagram analysis of all active regions observed by the Helioseismic and Magnetic Imager (HMI) during almost five years. We find that the frequency at which the mode amplitude changes from attenuation to amplification in the quiet nearby regions is around 4.2 mHz, in contrast to the active regions, for which it is about 5.1 mHz. This amplitude enhacement (the “acoustic halo effect”) is as large as that observed in the active regions, and has a very weak dependence on the wave propagation direction. The mode energy difference in nearby regions also changes from a deficit to an excess at around 4.2 mHz, but averages to zero over all modes. The frequency difference in nearby regions increases with increasing frequency until a point at which the frequency shifts turn over sharply, as in active regions. However, this turnover occurs around 4.9 mHz, which is significantly below the acoustic cutoff frequency. Inverting the horizontal flow parameters in the direction of the neigboring active regions, we find flows that are consistent with a model of the thermal energy flow being blocked directly below the active region.

  7. Activities of the Acoustical Society of America

    NASA Technical Reports Server (NTRS)

    2002-01-01

    During the period covered by this grant report, the following accomplishments were achieved: (1) 10 new American National Standards were adopted and published; (2) Five International Standards were adopted as dual-numbered American National Standards and published; (3) Six draft American National Standards were balloted (not yet adopted or published); (4) Other National Standards Ballots were processed by the Secretariat; (5) US Positions on International Standards Activities processed by the Secretariat; (6) Reporting was conducted at conferences.

  8. Vibrations of three-dimensional pipe systems with acoustic coupling

    NASA Technical Reports Server (NTRS)

    El-Raheb, M.

    1981-01-01

    A general algorithm is developed to calculate the beam-type dynamic response of three dimensional multiplane finite length pipe systems, consisting of elbow and straight ducts with continuous interfaces. Emphasis is on secondary acoustic wave effects giving rise to coupling mechanisms; and the simulation accounts for one-dimensional elastoacoustic coupling from a plane acoustic wave and secondary loads resulting from wave asymmetries. The transfer matrix approach is adopted in modeling the elastodynamics of each duct, with allowance for distribution loads. Secondary loads from plane wave distortion are considered with a solution of the Helmholtz equation in an equivalent rigid waveguide, and effects of path imperfection are introduced as a perturbation from the hypothetical perfectly straight pipe. Computations indicate that the one-dimensional acoustic assumption is valid for frequencies below one-half the first cut-off frequency, and the three-dimensional acoustic effects produce an increase in response levels near and above cut-off.

  9. Assessing acoustic communication active space in the Lusitanian toadfish.

    PubMed

    Alves, Daniel; Amorim, M Clara P; Fonseca, Paulo J

    2016-04-15

    The active space of a signal is an important concept in acoustic communication as it has implications for the function and evolution of acoustic signals. However, it remains mostly unknown for fish as it has been measured in only a restricted number of species. We combined physiological and sound propagation approaches to estimate the communication range of the Lusitanian toadfish's ( ITALIC! Halobatrachus didactylus) advertisement sound, the boatwhistle (BW). We recorded BWs at different distances from vocalizing fish in a natural nesting site at ca. 2-3 m depth. We measured the representation of these increasingly attenuated BWs in the auditory pathway through the auditory evoked potential (AEP) technique. These measurements point to a communication range of between 6 and 13 m, depending on the spectral characteristics of the BW. A similar communication range (ca. 8 m) was derived from comparing sound attenuation at selected frequencies with auditory sensitivity. This is one of the few studies to combine auditory measurements with sound propagation to estimate the active space of acoustic signals in fish. We emphasize the need in future studies for estimates of active space to take informational masking into account. PMID:26896547

  10. Activation of immobilized enzymes by acoustic wave resonance oscillation.

    PubMed

    Nishiyama, Hiroshi; Watanabe, Tomoya; Inoue, Yasunobu

    2014-12-01

    Acoustic wave resonance oscillation has been used successfully in the development of methods to activate immobilized enzyme catalysts. In this study, resonance oscillation effects were demonstrated for enzyme reactions on galactose oxidase (GAD), D-amino acid oxidase (DAAO), and L-amino acid oxidase (LAAO), all of which were immobilized covalently on a ferroelectric lead zirconate titanate (PZT) device that could generate thickness-extensional resonance oscillations (TERO) of acoustic waves. For galactose oxidation on immobilized GAD in a microreactor, TERO generation immediately increased enzyme activity 2- to 3-fold. Eliminating TERO caused a slight decrease in the activity, with ∼90% of the enhanced activity retained while the reaction proceeded. Contact of the enhanced enzyme with a galactose-free solution caused almost complete reversion of the activity to the original low level before TERO generation, indicating that, not only TERO-induced GAD activation, but also preservation of the increased activity, required a galactose substrate. Similar activity changes with TERO were observed for enzyme reactions on DAAO and LAAO. Kinetic analysis demonstrated that TERO helped strengthen the interactions of the immobilized enzyme with the reactant substrate and promoted formation of an activation complex. PMID:25442945

  11. Information and data real time transmission acoustic underwater system: TRIDENT

    NASA Astrophysics Data System (ADS)

    Trubuil, Joel; Labat, Joel; Lapierre, Gerard

    2001-05-01

    The objective of the Groupe d'Etudes Sous-Marines de l'Atlantique (GESMA) is to develop a robust high data rate acoustic link. A real-time receiver recently developed at ENST Bretagne has just been designed to cope with all perturbations induced by such harsh channels. In order to cope with channel features, a spatio-temporal equalizer introduced by J. Labat et al. [Brevet FT no. 9914844, ``Perfectionnements aux dispositifs d'galisation adaptative pour recepteurs de systemes de communications numriques,'' Nov. 1999] was recently implemented and evaluated. This equalizer is the core of the receiver platform [Trubuil et al., ``Real-time high data rate acoustic link based on spatio temporal blind equalization: the TRIDENT acoustic system,'' OCEANS 2002]. This paper provides an overview of this project. The context of the study and the design of high data rate acoustic link are presented. Last Brest harbor experiments (2002, 2003) are described. The real time horizontal acoustic link performances are evaluated. Two carriers frequencies are available (20, 35 kHz). Acoustic communications for bit rate ranging from 10 to 20 kbps and for channel length (shallow water) ranging from 500 to 4000 m have been conducted successfully over several hours.

  12. Microfluidic generation of acoustically active nanodroplets.

    PubMed

    Martz, Thomas D; Bardin, David; Sheeran, Paul S; Lee, Abraham P; Dayton, Paul A

    2012-06-25

    A microfluidic approach for the generation of perfluorocarbon nanodroplets as the primary emulsion with diameters as small as 300-400 nm is described. The system uses a pressure-controlled delivery of all reagents and increased viscosity in the continuous phase to drive the device into an advanced tip-streaming regime, which results in generation of droplets in the sub-micrometer range. Such nanodroplets may be appropriate for emerging biomedical applications. PMID:22467628

  13. A field-deployable digital acoustic measurement system

    NASA Technical Reports Server (NTRS)

    Gray, David L.; Wright, Kenneth D., II; Rowland, Wayne D.

    1991-01-01

    A field deployable digital acoustic measurement system was developed to support acoustic research programs at the Langley Research Center. The system digitizes the acoustic inputs at the microphone, which can be located up to 1000 feet from the van which houses the acquisition, storage, and analysis equipment. Digitized data from up to 12 microphones is recorded on high density 8mm tape and is analyzed post-test by a microcomputer system. Synchronous and nonsynchronous sampling is available with maximum sample rates of 12,500 and 40,000 samples per second respectively. The high density tape storage system is capable of storing 5 gigabytes of data at transfer rates up to 1 megabyte per second. System overall dynamic range exceeds 83 dB.

  14. Design, construction, activation, and operation of a high intensity acoustic test chamber

    NASA Technical Reports Server (NTRS)

    Kamel, L. T.

    1986-01-01

    The design philosophy, construction, integration, and activation of the high intensity acoustic test chamber for production acceptance testing of satellites are discussed. The 32,000 cubic-foot acoustic test cell consists of a steel reinforced concrete chamber with six electropneumatic noise generators. One of the innovative features of the chamber is a unique quarter horn assembly that acoustically couples the noise generators to the chamber. Design concepts, model testing, and evaluation results are presented. Considerations such as nitrogen versus compressed air source, digital closed loop spectrum control versus manual equalizers, and microprocessor based interlock systems are included. Construction difficulties, anomalies encountered, and their resolution are also discussed. Results of the readiness testing are highlighted.

  15. An explosive acoustic telemetry system for seabed penetrators

    SciTech Connect

    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.

  16. A novel acoustically quiet coil for neonatal MRI system

    PubMed Central

    Ireland, Christopher M.; Giaquinto, Randy O.; Loew, Wolfgang; Tkach, Jean A.; Pratt, Ronald G.; Kline-Fath, Beth M.; Merhar, Stephanie L.; Dumoulin, Charles L.

    2015-01-01

    MRI acoustic exposure has the potential to elicit physiological distress and impact development in preterm and term infants. To mitigate this risk, a novel acoustically quiet coil was developed to reduce the sound pressure level experienced by neonates during MR procedures. The new coil has a conventional high-pass birdcage RF design, but is built on a framework of sound abating material. We evaluated the acoustic and MR imaging performance of the quiet coil and a conventional body coil on two small footprint NICU MRI systems. Sound pressure level and frequency response measurements were made for six standard clinical MR imaging protocols. The average sound pressure level, reported for all six imaging pulse sequences, was 82.2 dBA for the acoustically quiet coil, and 91.1 dBA for the conventional body coil. The sound pressure level values measured for the acoustically quiet coil were consistently lower, 9 dBA (range 6-10 dBA) quieter on average. The acoustic frequency response of the two coils showed a similar harmonic profile for all imaging sequences. However, the amplitude was lower for the quiet coil, by as much as 20 dBA. PMID:26457072

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

    SciTech Connect

    Deng, Zhiqun; Weiland, Mark A.; Carlson, Thomas J.; Eppard, M. B.

    2010-03-31

    The Juvenile Salmon Acoustic Telemetry System (JSATS) is an active sensing technology developed by Portland District, the U.S. Army Corps of Engineers for detecting and tracking small fish. It is used at hydroelectric projects and in the laboratory 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 for evaluating the JSATS component, because the JSATS requires comprehensive acceptance and performance testing in a controlled environment before it is deployed in the field. The system 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 system has been evaluated successfully at various simulated distances and using different encoded signals at frequencies within the bandwidth of the JSATS transmitter. It 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 measurement and calibration system has been in use since 2009 for acceptance and performance testing of, and further improvements to, the JSATS.

  18. Effects of high activation energies on acoustic timescale detonation initiation

    NASA Astrophysics Data System (ADS)

    Regele, J. D.; Kassoy, D. R.; Vasilyev, O. V.

    2012-08-01

    Acoustic timescale Deflagration-to-Detonation Transition (DDT) has been shown to occur through the generation of compression waves emitted by a hot spot or reaction centre where the pressure and temperature increase with little diminution of density. In order to compensate for the multi-scale nature of the physico-chemical processes, previous numerical simulations in this area have been limited to relatively small activation energies. In this work, a computational study investigates the effect of increased activation energy on the time required to form a detonation wave and the change in behaviour of each hot spot as the activation energy is increased. The simulations use a localised spatially distributed thermal power deposition of limited duration into a finite volume of reactive gas to facilitate DDT. The Adaptive Wavelet-Collocation Method is used to solve efficiently the 1-D reactive Euler equations with one-step Arrhenius kinetics. The DDT process as described in previous work is characterised by the formation of hot spots during an initial transient period, explosion of the hot spots and creation of an accelerating reaction front that reaches the lead shock and forms an overdriven detonation wave. Current results indicate that as the activation energy is raised the chemical heat release becomes more temporally distributed. Hot spots that produce an accelerating reaction front with low activation energies change behaviour with increased activation energy so that no accelerating reaction front is created. An acoustic timescale ratio is defined that characterises the change in behaviour of each hot spot.

  19. Computation of instantaneous and time-averaged active acoustic intensity field around rotating source

    NASA Astrophysics Data System (ADS)

    Mao, Yijun; Xu, Chen; Qi, Datong

    2015-02-01

    A vector aeroacoustics method is developed to analyze the acoustic energy flow path from the rotating source. In this method, the instantaneous and time-averaged active acoustic intensity vectors are evaluated from the time-domain and frequency-domain acoustic pressure and acoustic velocity formulations, respectively. With the above method, the acoustic intensity vectors and the acoustic energy streamlines are visualized to investigate the propagation feature of the noise radiated from the monopole and dipole point sources and the rotor in subsonic rotation. The result reveals that a portion of the acoustic energy spirals many circles before moving towards the far field, and another portion of the acoustic energy firstly flows inward along the radial direction and then propagates along the axial direction. Further, an acoustic black hole exists in the plane of source rotation, from which the acoustic energy cannot escape once the acoustic energy flows into it. Moreover, by visualizing the acoustic intensity field around the rotating sources, the acoustic-absorption performance of the acoustic liner built in the casing and centerbody is discussed.

  20. Helicopter acoustic alerting system for high-security facilities

    NASA Astrophysics Data System (ADS)

    Steadman, Robert L.; Hansen, Scott; Park, Chris; Power, Dennis

    2009-05-01

    Helicopters present a serious threat to high security facilities such as prisons, nuclear sites, armories, and VIP compounds. They have the ability to instantly bypass conventional security measures focused on ground threats such as fences, check-points, and intrusion sensors. Leveraging the strong acoustic signature inherent in all helicopters, this system would automatically detect, classify, and accurately track helicopters using multi-node acoustic sensor fusion. An alert would be generated once the threat entered a predefined 3-dimension security zone in time for security personnel to repel the assault. In addition the system can precisely identify the landing point on the facility grounds.

  1. Statistical analysis of storm electrical discharges reconstituted from a lightning mapping system, a lightning location system, and an acoustic array

    NASA Astrophysics Data System (ADS)

    Gallin, Louis-Jonardan; Farges, Thomas; Marchiano, Régis; Coulouvrat, François; Defer, Eric; Rison, William; Schulz, Wolfgang; Nuret, Mathieu

    2016-04-01

    In the framework of the European Hydrological Cycle in the Mediterranean Experiment project, a field campaign devoted to the study of electrical activity during storms took place in the south of France in 2012. An acoustic station composed of four microphones and four microbarometers was deployed within the coverage of a Lightning Mapping Array network. On the 26 October 2012, a thunderstorm passed just over the acoustic station. Fifty-six natural thunder events, due to cloud-to-ground and intracloud flashes, were recorded. This paper studies the acoustic reconstruction, in the low frequency range from 1 to 40 Hz, of the recorded flashes and their comparison with detections from electromagnetic networks. Concurrent detections from the European Cooperation for Lightning Detection lightning location system were also used. Some case studies show clearly that acoustic signal from thunder comes from the return stroke but also from the horizontal discharges which occur inside the clouds. The huge amount of observation data leads to a statistical analysis of lightning discharges acoustically recorded. Especially, the distributions of altitudes of reconstructed acoustic detections are explored in detail. The impact of the distance to the source on these distributions is established. The capacity of the acoustic method to describe precisely the lower part of nearby cloud-to-ground discharges, where the Lightning Mapping Array network is not effective, is also highlighted.

  2. Performance evaluation of a biometric system based on acoustic images.

    PubMed

    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

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

    PubMed Central

    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

  4. A wireless data acquisition system for acoustic emission testing

    NASA Astrophysics Data System (ADS)

    Zimmerman, A. T.; Lynch, J. P.

    2013-01-01

    As structural health monitoring (SHM) systems have seen increased demand due to lower costs and greater capabilities, wireless technologies have emerged that enable the dense distribution of transducers and the distributed processing of sensor data. In parallel, ultrasonic techniques such as acoustic emission (AE) testing have become increasingly popular in the non-destructive evaluation of materials and structures. These techniques, which involve the analysis of frequency content between 1 kHz and 1 MHz, have proven effective in detecting the onset of cracking and other early-stage failure in active structures such as airplanes in flight. However, these techniques typically involve the use of expensive and bulky monitoring equipment capable of accurately sensing AE signals at sampling rates greater than 1 million samples per second. In this paper, a wireless data acquisition system is presented that is capable of collecting, storing, and processing AE data at rates of up to 20 MHz. Processed results can then be wirelessly transmitted in real-time, creating a system that enables the use of ultrasonic techniques in large-scale SHM systems.

  5. Active Path Selection of Fluid Microcapsules in Artificial Blood Vessel by Acoustic Radiation Force

    NASA Astrophysics Data System (ADS)

    Masuda, Kohji; Muramatsu, Yusuke; Ueda, Sawami; Nakamoto, Ryusuke; Nakayashiki, Yusuke; Ishihara, Ken

    2009-07-01

    Micrometer-sized microcapsules collapse upon exposure to ultrasound. Use of this phenomenon for a drug delivery system (DDS), not only for local delivery of medication but also for gene therapy, should be possible. However, enhancing the efficiency of medication is limited because capsules in suspension diffuse in the human body after injection, since the motion of capsules in blood flow cannot be controlled. To control the behavior of microcapsules, acoustic radiation force was introduced. We detected local changes in microcapsule density by producing acoustic radiation force in an artificial blood vessel. Furthermore, we theoretically estimated the conditions required for active path selection of capsules at a bifurcation point in the artificial blood vessel. We observed the difference in capsule density at both in the bifurcation point and in alternative paths downstream of the bifurcation point for different acoustic radiation forces. Comparing the experimental results with those obtained theoretically, the conditions for active path selection were calculated from the acoustic radiation force and fluid resistance of the capsules. The possibility of controlling capsule flow towards a specific point in a blood vessel was demonstrated.

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

    PubMed Central

    Deng, Zhiqun; Weiland, Mark; Carlson, Thomas; Eppard, M. Brad

    2010-01-01

    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. PMID:22319288

  7. Design and instrumentation of a measurement and calibration system for an acoustic telemetry system.

    PubMed

    Deng, Zhiqun; Weiland, Mark; Carlson, Thomas; Eppard, M Brad

    2010-01-01

    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. PMID:22319288

  8. System and method for sonic wave measurements using an acoustic beam source

    DOEpatents

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian

    2015-08-11

    A method and system for investigating structure near a borehole are described herein. The method includes generating an acoustic beam by an acoustic source; directing at one or more azimuthal angles the acoustic beam towards a selected location in a vicinity of a borehole; receiving at one or more receivers an acoustic signal, the acoustic signal originating from a reflection or a refraction of the acoustic wave by a material at the selected location; and analyzing the received acoustic signal to characterize features of the material around the borehole.

  9. Analytical study of acoustically perturbed Brillouin active magnetized semiconductor plasma

    SciTech Connect

    Shukla, Arun; Jat, K. L.

    2015-07-31

    An analytical study of acoustically perturbed Brillouin active magnetized semiconductor plasma has been reported. In the present analytical investigation, the lattice displacement, acousto-optical polarization, susceptibility, acousto-optical gain constant arising due to the induced nonlinear current density and acousto-optical process are deduced in an acoustically perturbed Brillouin active magnetized semiconductor plasma using the hydrodynamical model of plasma and coupled mode scheme. The influence of wave number and magnetic field has been explored. The analysis has been applied to centrosymmetric crystal. Numerical estimates are made for n-type InSb crystal duly irradiated by a frequency doubled 10.6 µm CO{sub 2} laser. It is found that lattice displacement, susceptibility and acousto-optical gain increase linearly with incident wave number and applied dc magnetic field, while decrease with scattering angle. The gain also increases with electric amplitude of incident laser beam. Results are found to be well in agreement with available literature.

  10. Design of an acoustic telemetry system for rebreathers.

    PubMed

    Egi, S M

    2009-01-01

    Despite the abundance of telemetric applications for ecology, behavior and physiology of marine life, few efforts were reported about the use of acoustic telemetry for SCUBA divers. The objective of this study is to design and test an acoustic telemetry system for monitoring breathing gases of a Dräger Dolphin semi-closed circuit rebreather as well as the depth of the diver. The system is designed around a PC based surface unit and a microcontroller based diver carried module that digitizes the output of CO2 and O2 sensors located in the inhalation side of the canister. One pair of acoustic modems establishes the data link between the microcontroller and the topside PC. The graphical user interface is written in C# and enables the recording of the diving session as well. The system is calibrated in a hyperbaric chamber and tested successfully with four dives in three different environments using 100% O2 and Nitrox (47.9% O2 - 52.1% N2) up to 15 m depth and a distance of 40 m between acoustic modems. The telemetry data cannot be used only for recording physiological data but also provides an important operational safety tool to monitor the rebreather user. The future designs will include actuators for controlling the diluent and oxygen flow to closed circuit mix gas rebreathers. PMID:19341129

  11. Resonant acoustic transducer and driver system for a well drilling string communication system

    DOEpatents

    Chanson, Gary J.; Nicolson, Alexander M.

    1981-01-01

    The acoustic data communication system includes an acoustic transmitter and receiver wherein low frequency acoustic waves, propagating in relatively loss free manner in well drilling string piping, are efficiently coupled to the drill string and propagate at levels competitive with the levels of noise generated by drilling machinery also present in the drill string. The transmitting transducer incorporates a mass-spring piezoelectric transmitter and amplifier combination that permits self-oscillating resonant operation in the desired low frequency range.

  12. Acoustic design criteria in a general system for structural optimization

    NASA Technical Reports Server (NTRS)

    Brama, Torsten

    1990-01-01

    Passenger comfort is of great importance in most transport vehicles. For instance, in the new generation of regional turboprop aircraft, a low noise level is vital to be competitive on the market. The possibilities to predict noise levels analytically has improved rapidly in recent years. This will make it possible to take acoustic design criteria into account in early project stages. The development of the ASKA FE-system to include also acoustic analysis has been carried out at Saab Aircraft Division and the Aeronautical Research Institute of Sweden in a joint project. New finite elements have been developed to model the free fluid, porous damping materials, and the interaction between the fluid and structural degrees of freedom. The FE approach to the acoustic analysis is best suited for lower frequencies up to a few hundred Hz. For accurate analysis of interior cabin noise, large 3-D FE-models are built, but 2-D models are also considered to be useful for parametric studies and optimization. The interest is here focused on the introduction of an acoustic design criteria in the general structural optimization system OPTSYS available at the Saab Aircraft Division. The first implementation addresses a somewhat limited class of problems. The problems solved are formulated: Minimize the structural weight by modifying the dimensions of the structure while keeping the noise level in the cavity and other structural design criteria within specified limits.

  13. A Novel Analysis of Acoustic Oscillations in Chromospheric Active Regions

    NASA Astrophysics Data System (ADS)

    Monsue, Teresa; Hill, Frank; Stassun, Keivan G.

    2015-04-01

    A helioseismic analysis of the chromosphere is employed in H-alpha to study how solar flares around active regions affect the behavior of acoustic oscillations. Our analysis deals with flares directly over sunspots, where the region is highly magnetized. In our current study of analyzing these oscillations in the chromosphere we study the temporal evolution of the oscillatory behavior from data taken from the Global Oscillation Network Group (GONG) H-alpha detectors. We investigate the wave behavior across different frequency bands (1 < ν < 8.33 mHz). In order to analyze the frequency bands of the oscillations, our analysis utilizes time series data to create Fourier power spectra of individual pixels spatially resolved and temporally evolved around the flare region; thereby creating a movie of each frequency band. This study entails three active regions, directly over sunspots, in which flaring activity is taking place from two solar flares, which occurred on June 13th and July 12th, 2012. We found that the intensity of the flare has an effect on the oscillations within different frequency bands. A suppression of power was observed in dark anomalous structures across the total frequency bands and in other regions there was an observed boost in power due to flaring activity. We find that, in the heart of all three regions, the low-frequency power (˜1-2 mHz) is substantially enhanced immediately prior to and after the flare, and that power at all frequencies up to 8 mHz is depleted at flare maximum. This depletion is both frequency and time dependent, which probably reflects the changing depths visible during the flare in the bandpass of the filter. These variations are not observed outside the flaring region. The depletion may indicate that acoustic energy is being converted into thermal energy at flare maximum, while the low-frequency enhancement may arise from an instability in the chromosphere and provide an early warning of the flare onset.

  14. THE ACOUSTIC CUTOFF FREQUENCY OF THE SUN AND THE SOLAR MAGNETIC ACTIVITY CYCLE

    SciTech Connect

    Jimenez, A.; Palle, P. L.; Garcia, R. A.

    2011-12-20

    The acoustic cutoff frequency-the highest frequency for acoustic solar eigenmodes-is an important parameter of the solar atmosphere as it determines the upper boundary of the p-mode resonant cavities. At frequencies beyond this value, acoustic disturbances are no longer trapped but are traveling waves. Interference among them gives rise to higher-frequency peaks-the pseudomodes-in the solar acoustic spectrum. The pseudomodes are shifted slightly in frequency with respect to p-modes, making possible the use of pseudomodes to determine the acoustic cutoff frequency. Using data from the GOLF and VIRGO instruments on board the Solar and Heliospheric Observatory spacecraft, we calculate the acoustic cutoff frequency using the coherence function between both the velocity and intensity sets of data. By using data gathered by these instruments during the entire lifetime of the mission (1996 until the present), a variation in the acoustic cutoff frequency with the solar magnetic activity cycle is found.

  15. Designing piping systems against acoustically-induced structural fatigue

    SciTech Connect

    Eisinger, F.L.

    1996-12-01

    Piping systems adapted for handling fluids such as steam and various process and hydrocarbon gases through a pressure-reducing device at high pressure and velocity conditions can produce severe acoustic vibration and metal fatigue in the system. It has been determined that such vibrations and fatigue are minimized by relating the acoustic power level (PWL) to being a function of the ratio of downstream pipe inside diameter D{sub 2} to its thickness t{sub 2}. Additionally, such vibration and fatigue can be further minimized by relating the fluid pressure drop and downstream mach number to a function of the ratio of downstream piping inside diameter to the pipe wall thickness, as expressed by M{sub 2} {Delta}p = f(D{sub 2}/t{sub 2}). Pressure-reducing piping systems designed according to these criteria exhibit minimal vibrations and metal fatigue failures and have long operating life.

  16. Synthetic gauge flux and Weyl points in acoustic systems

    NASA Astrophysics Data System (ADS)

    Xiao, Meng; Chen, Wen-Jie; He, Wen-Yu; Chan, C. T.

    2015-11-01

    Following the discovery of the quantum Hall effect and topological insulators, the topological properties of classical waves began to draw attention. Topologically non-trivial bands characterized by non-zero Chern numbers are realized through either the breaking of time-reversal symmetry using an external magnetic field or dynamic modulation. Owing to the absence of a Faraday-like effect, the breaking of time-reversal symmetry in an acoustic system is commonly realized with moving background fluids, which drastically increases the engineering complexity. Here we show that we can realize effective inversion symmetry breaking and create an effective gauge flux in a reduced two-dimensional system by engineering interlayer couplings, achieving an acoustic analogue of the topological Haldane model. We show that the synthetic gauge flux is closely related to Weyl points in the three-dimensional band structure and the system supports chiral edge states for fixed values of kz.

  17. PC-based Digital Acoustic Control System (DACS)

    NASA Technical Reports Server (NTRS)

    Shah, Kamlesh C.

    1991-01-01

    The PC-based Digital Acoustic Control System (DACS), which is a closed-loop system capable of precisely controlling the spectrum in real-time mode, is discussed. The system is based on integrated facility hardware including control microphones, signal conditioners, a real-time analyzer (RTA), a shaper, high capacity power amplifiers, and acoustic horns and generators. The DACS provides both an improved spectrum simulation and realtime information of pertinent test parameters that are stored in five separate files. These files can be hard copied and/or transferred to other programs to obtain a specific format of the test data. It is demonstrated that the computer interface with digital RTA and programmable filters are most effective and efficient. This facility runs independently under the control of a computer with an IEEE-488 interface to the facility hardware.

  18. The acoustic simulation and analysis of complicated reciprocating compressor piping systems, I: Analysis technique and parameter matrices of acoustic elements

    NASA Astrophysics Data System (ADS)

    To, C. W. S.

    1984-09-01

    This paper describes the mathematical formulation, equations, and procedures employed in the development of a comprehensive digital computer program for acoustic simulation and analysis of large and complicated piping systems. The analysis technique used is the transfer matrix method in which the piping system, with or without multiple inputs and outputs, is represented by a combination of discrete acoustic elements interconnected to one another at two stations such that the acoustic pressure and volume velocity at one station are uniquely related to those at the other by a two-by-two parameter matrix. Parameter matrices of 19 acoustic elements are included in this paper. By making use of these parameter matrices and the analysis technique, any complicated practical reciprocating compressor piping system can be modelled or analyzed.

  19. Acoustic system for communication in pipelines

    DOEpatents

    Martin, II, Louis Peter; Cooper, John F.

    2008-09-09

    A system for communication in a pipe, or pipeline, or network of pipes containing a fluid. The system includes an encoding and transmitting sub-system connected to the pipe, or pipeline, or network of pipes that transmits a signal in the frequency range of 3-100 kHz into the pipe, or pipeline, or network of pipes containing a fluid, and a receiver and processor sub-system connected to the pipe, or pipeline, or network of pipes containing a fluid that receives said signal and uses said signal for a desired application.

  20. Optical Sensor/Actuator Locations for Active Structural Acoustic Control

    NASA Technical Reports Server (NTRS)

    Padula, Sharon L.; Palumbo, Daniel L.; Kincaid, Rex K.

    1998-01-01

    Researchers at NASA Langley Research Center have extensive experience using active structural acoustic control (ASAC) for aircraft interior noise reduction. One aspect of ASAC involves the selection of optimum locations for microphone sensors and force actuators. This paper explains the importance of sensor/actuator selection, reviews optimization techniques, and summarizes experimental and numerical results. Three combinatorial optimization problems are described. Two involve the determination of the number and position of piezoelectric actuators, and the other involves the determination of the number and location of the sensors. For each case, a solution method is suggested, and typical results are examined. The first case, a simplified problem with simulated data, is used to illustrate the method. The second and third cases are more representative of the potential of the method and use measured data. The three case studies and laboratory test results establish the usefulness of the numerical methods.

  1. Acoustic stress activates tuberoinfundibular peptide of 39 residues neurons in the rat brain

    PubMed Central

    Palkovits, Miklós; Helfferich, Frigyes; Dobolyi, Árpád; Usdin, Ted B.

    2010-01-01

    Strong acoustic stimulation (105 dB SPL white noise) elicited c-fos expression in neurons in several acoustic system nuclei and in stress-sensitive hypothalamic nuclei and limbic areas in rats. In the present study, using this type of loud noise for 30 min, Fos-like immunoreactivity (Fos-ir) was investigated in neurons that synthesize tuberoinfundibular peptide of 39 residues (TIP39) in the rat brain: in the subparafascicular area of the thalamus, the posterior intralaminar complex of the thalamus and the medial paralemniscal nucleus in the lateral part of the pons. By double labeling, Fos-ir was shown in nearly 80% of TIP39-positive cells in the medial paralemniscal nucleus, 43% in the posterior intralaminar complex and 18.5% in the subparafascicular area 30 min after the end of a 30-min loud noise period. In control rats, only few neurons, including 0–4% of TIP39-positive neurons showed Fos-ir. While the majority of the Fos-ir neurons were TIP39-positive in the subparafascicular area and medial paralemniscal nucleus, a fairly high number of TIP39-immunonegative, chemically uncharacterized neurons expressed c-fos in the subparafascicular area and the posterior intralaminar complex of the thalamus. These observations clearly show that some TIP39 neurons in the so-called “acoustic thalamus” and the majority of TIP39 neurons in the medial paralemniscal nucleus are sensitive to loud noise and they may participate in the central organization of responses to acoustic stress. Furthermore, the present data suggest that non-TIP39-expressing neurons may play a prevalent role in the activity of the “acoustic thalamus”. PMID:19936783

  2. Study on demodulated signal distribution and acoustic pressure phase sensitivity of a self-interfered distributed acoustic sensing system

    NASA Astrophysics Data System (ADS)

    Shang, Ying; Yang, Yuan-Hong; Wang, Chen; Liu, Xiao-Hui; Wang, Chang; Peng, Gang-Ding

    2016-06-01

    We propose a demodulated signal distribution theory for a self-interfered distributed acoustic sensing system. The distribution region of Rayleigh backscattering including the acoustic sensing signal in the sensing fiber is investigated theoretically under different combinations of both the path difference and pulse width Additionally we determine the optimal solution between the path difference and pulse width to obtain the maximum phase change per unit length. We experimentally test this theory and realize a good acoustic pressure phase sensitivity of  ‑150 dB re rad/(μPa·m) of fiber in the frequency range from 200 Hz to 1 kHz.

  3. Early forest fire detection using radio-acoustic sounding system.

    PubMed

    Sahin, Yasar Guneri; Ince, Turker

    2009-01-01

    Automated early fire detection systems have recently received a significant amount of attention due to their importance in protecting the global environment. Some emergent technologies such as ground-based, satellite-based remote sensing and distributed sensor networks systems have been used to detect forest fires in the early stages. In this study, a radio-acoustic sounding system with fine space and time resolution capabilities for continuous monitoring and early detection of forest fires is proposed. Simulations show that remote thermal mapping of a particular forest region by the proposed system could be a potential solution to the problem of early detection of forest fires. PMID:22573967

  4. Early Forest Fire Detection Using Radio-Acoustic Sounding System

    PubMed Central

    Sahin, Yasar Guneri; Ince, Turker

    2009-01-01

    Automated early fire detection systems have recently received a significant amount of attention due to their importance in protecting the global environment. Some emergent technologies such as ground-based, satellite-based remote sensing and distributed sensor networks systems have been used to detect forest fires in the early stages. In this study, a radio-acoustic sounding system with fine space and time resolution capabilities for continuous monitoring and early detection of forest fires is proposed. Simulations show that remote thermal mapping of a particular forest region by the proposed system could be a potential solution to the problem of early detection of forest fires. PMID:22573967

  5. a Three-Dimensional Acoustical Imaging System for Zooplankton Observations

    NASA Astrophysics Data System (ADS)

    McGehee, Duncan Ewell

    This dissertation describes the design, testing, and use of a three-dimensional acoustical imaging system, called Fish TV, or FTV, for tracking zooplankton swimming in situ. There is an increasing recognition that three -dimensional tracks of individual plankters are needed for some studies in behavioral ecology including, for example, the role of individual behavior in patch formation and maintenance. Fish TV was developed in part to provide a means of examining zooplankton swimming behavior in a non-invasive way. The system works by forming a set of 64 acoustic beams in an 8 by 8 pattern, each beam 2 ^circ by 2^circ , for a total coverage of 16^circ by 16^circ. The 8 by 8 beams form two dimensions of the image; range provides the third dimension. The system described in the thesis produces three-dimensional images at the rate of approximately one per second. A set of laboratory and field experiments is described that demonstrates the capabilities of the system. The final field experiment was the in situ observation of zooplankton swimming behavior at a site in the San Diego Trough, 15 nautical miles southwest of San Diego. 314 plankters were tracked for one minute. It was observed that there was no connection between the acoustic size of the animals and their repertoire of swimming behaviors. Other contributions of the dissertation include the development of two novel methods for generating acoustic beams with low side lobes. The first is the method of dense random arrays. The second is the optimum mean square quantized aperture method. Both methods were developed originally as ways to "build a better beam pattern" for Fish TV, but also have general significance with respect to aperture theory.

  6. Active Cancellation of Acoustical Resonances with an FPGA FIR Filter

    NASA Astrophysics Data System (ADS)

    Ryou, Albert; Simon, Jonathan

    2016-05-01

    We demonstrate a novel approach to enhancing the closed-loop bandwidth of a feedback-controlled mechanical system by digitally cancelling its acoustical resonances and antiresonances with an FPGA FIR filter. By performing a real-time convolution of the feedback error signal with an arbitrary filter, we can suppress arbitrarily many poles and zeros below 100 kHz, each with a linewidth as small as 10 Hz. We demonstrate the efficacy of this technique by cancelling the six largest resonances and antiresonances of a high-finesse optical resonator piezomechanical transfer function, thereby enhancing the unity gain frequency by more than an order of magnitude. More broadly, this approach is applicable to stabilization of optical resonators, external cavity diode lasers, and scanning tunneling microscopes.

  7. Acoustic leak-detection system for railroad transportation security

    NASA Astrophysics Data System (ADS)

    Womble, P. C.; Spadaro, J.; Harrison, M. A.; Barzilov, A.; Harper, D.; Hopper, L.; Houchins, E.; Lemoff, B.; Martin, R.; McGrath, C.; Moore, R.; Novikov, I.; Paschal, J.; Rogers, S.

    2007-04-01

    Pressurized rail tank cars transport large volumes of volatile liquids and gases throughout the country, much of which is hazardous and/or flammable. These gases, once released in the atmosphere, can wreak havoc with the environment and local populations. We developed a system which can non-intrusively and non-invasively detect and locate pinhole-sized leaks in pressurized rail tank cars using acoustic sensors. The sound waves from a leak are produced by turbulence from the gas leaking to the atmosphere. For example, a 500 μm hole in an air tank pressurized to 689 kPa produces a broad audio frequency spectrum with a peak near 40 kHz. This signal is detectable at 10 meters with a sound pressure level of 25 dB. We are able to locate a leak source using triangulation techniques. The prototype of the system consists of a network of acoustic sensors and is located approximately 10 meters from the center of the rail-line. The prototype has two types of acoustic sensors, each with different narrow frequency response band: 40 kHz and 80 kHz. The prototype is connected to the Internet using WiFi (802.11g) transceiver and can be remotely operated from anywhere in the world. The paper discusses the construction, operation and performance of the system.

  8. Mean Flow Augmented Acoustics in Rocket Systems

    NASA Technical Reports Server (NTRS)

    Fischbach, Sean R.

    2015-01-01

    Combustion instability in solid rocket motors and liquid engines is a complication that continues to plague designers and engineers. Many rocket systems experience violent fluctuations in pressure, velocity, and temperature originating from the complex interactions between the combustion process and gas dynamics. During sever cases of combustion instability fluctuation amplitudes can reach values equal to or greater than the average chamber pressure. Large amplitude oscillations lead to damaged injectors, loss of rocket performance, damaged payloads, and in some cases breach of case/loss of mission. Historic difficulties in modeling and predicting combustion instability has reduced most rocket systems experiencing instability into a costly fix through testing paradigm or to scrap the system entirely.

  9. Use of acoustic monitoring system for debris flow discharge evaluation

    NASA Astrophysics Data System (ADS)

    Galgaro, A. G.; Tecca, P. R.; Genevois, R.; Deganutti, A. M.

    2003-04-01

    In 1997 an automated system for monitoring of debris flows has been installed in the Acquabona channel Dolomites, Italy. Induction geophones, with a specific frequency of 10 Hz, measure the amplitude of vertical ground vibrations generated by the passage of a flowing mass along the channel. Continuous acoustic logs and ultrasonic hydrograph recorded at the lower-channel measurement station for the debris flow of August 17, 1998, show a striking correspondence. This correspondence, already observed in different flow sites, is represented by the best fit between flow depth and flow sensor amplitude. Average front velocity for surges, calculated from the signal peak time shift and the distance between the sensors along the flow path, range between 2.00 and 7.7 m/s. As the ultrasonic sensor provides a way to measure the variation of the flow section area with the flow depth, the debris flow peak discharge may be estimated; obtained values of debris flow peak discharge range from 4 and 30 m3/s. Volumes were calculated by integrating instantaneous discharges through the hydrograph and by integrating the geophone log (acoustic flux). Volumes of 13700 m3 and 15500 m3 have been respectively obtained. The slight difference between the two values may result from the fact that acoustic records: i) are sensitive to the high frequencies, typical of the debris flow tails; ii) sum up the contributions sent by the whole flowing mass, while the ecometer detect the flow depth at every time at only one section. As a consequence the rising of the whole geophone log gives a higher value at the integration result. This only acoustic system can give a reasonably proxy for discharge and total volumes involved, which are among the most important parameters for debris flow hazard assessment and planning countermeasures. This methodology can be used in other debris flow sites if they are calibrated by the acoustic characterization of debris, obtained by both seismic surveys and SPT tests, and

  10. Numerical Comparison of Active Acoustic and Structural Noise Control in a Stiffened Double Wall Cylinder

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.

    1996-01-01

    The active acoustic and structural noise control characteristics of a double wall cylinder with and without ring stiffeners were numerically evaluated. An exterior monopole was assumed to acoustically excite the outside of the double wall cylinder at an acoustic cavity resonance frequency. Structural modal vibration properties of the inner and outer shells were analyzed by post-processing the results from a finite element analysis. A boundary element approach was used to calculate the acoustic cavity response and the coupled structural-acoustic interaction. In the frequency region of interest, below 500 Hz, all structural resonant modes were found to be acoustically slow and the nonresonant modal response to be dominant. Active sound transmission control was achieved by control forces applied to the inner or outer shell, or acoustic control monopoles placed just outside the inner or outer shell. A least mean square technique was used to minimize the interior sound pressures at the nodes of a data recovery mesh. Results showed that single acoustic control monopoles placed just outside the inner or outer shells resulted in better sound transmission control than six distributed point forces applied to either one of the shells. Adding stiffeners to the double wall structure constrained the modal vibrations of the shells, making the double wall stiffer with associated higher modal frequencies. Active noise control obtained for the stiffened double wall configurations was less than for the unstiffened cylinder. In all cases, the acoustic control monopoles controlled the sound transmission into the interior better than the structural control forces.

  11. Exhaust System Experiments at NASA's AeroAcoustic Propulsion Lab

    NASA Technical Reports Server (NTRS)

    Bridges, James

    2011-01-01

    This presentation gives an overview of the planned testing in the AeroAcoustic Propulsion Lab (AAPL) in the coming 15 months. It was stressed in the presentation that these are plans that are subject to change due to changes in funding and/or programmatic direction. The first chart shows a simplified schedule of test entries with funding sponsor and dates for each. In subsequent charts are pages devoted to the Objectives and Issues with each test entry, along with a graphic intended to represent the test activity. The chart for each test entry also indicates sponsorship of the activity, and a contact person.!

  12. Passive acoustic monitoring of human physiology during activity indicates health and performance of soldiers and firefighters

    NASA Astrophysics Data System (ADS)

    Scanlon, Michael V.

    2003-04-01

    The Army Research Laboratory has developed a unique gel-coupled acoustic physiological monitoring sensor that has acoustic impedance properties similar to the skin. This facilitates the transmission of body sounds into the sensor pad, yet significantly repels ambient airborne noises due to an impedance mismatch. The sensor's sensitivity and bandwidth produce excellent signatures for detection and spectral analysis of diverse physiological events. Acoustic signal processing detects heartbeats, breaths, wheezes, coughs, blood pressure, activity, motion, and voice for communication and automatic speech recognition. The health and performance of soldiers, firefighters, and other first responders in strenuous and hazardous environments can be continuously and remotely monitored with body-worn acoustic sensors. Comfortable acoustic sensors can be in a helmet or in a strap around the neck, chest, and wrist. Noise-canceling sensor arrays help remove out-of-phase motion noise and enhance covariant physiology by using two acoustic sensors on the front sides of the neck and two additional acoustic sensors on each wrist. Pulse wave transit time between neck and wrist acoustic sensors will indicate systolic blood pressure. Larger torso-sized arrays can be used to acoustically inspect the lungs and heart, or built into beds for sleep monitoring. Acoustics is an excellent input for sensor fusion.

  13. Optimal flushing agents for integrated optical and acoustic imaging systems

    PubMed Central

    Li, Jiawen; Minami, Hataka; Steward, Earl; Ma, Teng; Mohar, Dilbahar; Robertson, Claire; Shung, Kirk; Zhou, Qifa; Patel, Pranav; Chen, Zhongping

    2015-01-01

    Abstract. An increasing number of integrated optical and acoustic intravascular imaging systems have been developed and hold great promise for accurately diagnosing vulnerable plaques and guiding atherosclerosis treatment. However, in any intravascular environment, the vascular lumen is filled with blood, a high-scattering source for optical and high-frequency ultrasound signals. Blood must be flushed away to provide clearer images. To our knowledge, no research has been performed to find the ideal flushing agent for combined optical and acoustic imaging techniques. We selected three solutions as potential flushing agents for their image-enhancing effects: mannitol, dextran, and iohexol. Testing of these flushing agents was performed in a closed-loop circulation model and in vivo on rabbits. We found that a high concentration of dextran was the most useful for simultaneous intravascular ultrasound and optical coherence tomography imaging. PMID:25985096

  14. Optimal flushing agents for integrated optical and acoustic imaging systems.

    PubMed

    Li, Jiawen; Minami, Hataka; Steward, Earl; Ma, Teng; Mohar, Dilbahar; Robertson, Claire; Shung, Kirk; Zhou, Qifa; Patel, Pranav; Chen, Zhongping

    2015-05-01

    An increasing number of integrated optical and acoustic intravascular imaging systems have been developed and hold great promise for accurately diagnosing vulnerable plaques and guiding atherosclerosis treatment. However, in any intravascular environment, the vascular lumen is filled with blood, a high-scattering source for optical and high-frequency ultrasound signals. Blood must be flushed away to provide clearer images. To our knowledge, no research has been performed to find the ideal flushing agent for combined optical and acoustic imaging techniques. We selected three solutions as potential flushing agents for their image-enhancing effects: mannitol, dextran, and iohexol. Testing of these flushing agents was performed in a closed-loop circulation model and in vivo on rabbits. We found that a high concentration of dextran was the most useful for simultaneous intravascular ultrasound and optical coherence tomography imaging. PMID:25985096

  15. Optimal flushing agents for integrated optical and acoustic imaging systems

    NASA Astrophysics Data System (ADS)

    Li, Jiawen; Minami, Hataka; Steward, Earl; Ma, Teng; Mohar, Dilbahar; Robertson, Claire; Shung, Kirk; Zhou, Qifa; Patel, Pranav; Chen, Zhongping

    2015-05-01

    An increasing number of integrated optical and acoustic intravascular imaging systems have been developed and hold great promise for accurately diagnosing vulnerable plaques and guiding atherosclerosis treatment. However, in any intravascular environment, the vascular lumen is filled with blood, a high-scattering source for optical and high-frequency ultrasound signals. Blood must be flushed away to provide clearer images. To our knowledge, no research has been performed to find the ideal flushing agent for combined optical and acoustic imaging techniques. We selected three solutions as potential flushing agents for their image-enhancing effects: mannitol, dextran, and iohexol. Testing of these flushing agents was performed in a closed-loop circulation model and in vivo on rabbits. We found that a high concentration of dextran was the most useful for simultaneous intravascular ultrasound and optical coherence tomography imaging.

  16. Ideal flushing agents for integrated optical acoustic imaging systems

    NASA Astrophysics Data System (ADS)

    Li, Jiawen; Minami, Hataka; Steward, Earl; Ma, Teng; Mohar, Dilbahar; Robertson, Claire; Shung, K. Kirk; Zhou, Qifa; Patel, Pranav M.; Chen, Zhongping

    2015-02-01

    An increased number of integrated optical acoustic intravascular imaging systems have been researched and hold great hope for accurate diagnosing of vulnerable plaques and for guiding atherosclerosis treatment. However, in any intravascular environment, vascular lumen is filled with blood, which is a high-scattering source for optical and high frequency ultrasound signals. Blood must be flushed away to make images clear. To our knowledge, no research has been performed to find the ideal flushing agent that works for both optical and acoustic imaging techniques. We selected three solutions, mannitol, dextran and iohexol, as flushing agents because of their image-enhancing effects and low toxicities. Quantitative testing of these flushing agents was performed in a closed loop circulation model and in vivo on rabbits.

  17. Ray chaos in an architectural acoustic semi-stadium system.

    PubMed

    Yu, Xiaojian; Zhang, Yu

    2013-03-01

    The semi-stadium system is composed of a semicircular cap and a rectilinear platform. In this study, a dynamic model of the side, position, and angle variables is applied to investigate the acoustic ray chaos of the architectural semi-stadium system. The Lyapunov exponent is calculated in order to quantitatively describe ray instability. The model can be reduced to the semi-circular and rectilinear platform systems when the rectilinear length is sufficiently small and large. The quasi-rectilinear platform and the semicircular systems both produce regular trajectories with the maximal Lyapunov exponent approaching zero. Ray localizations, such as flutter-echo and sound focusing, are found in these two systems. However, the semi-stadium system produces chaotic ray behaviors with positive Lyapunov exponents and reduces ray localizations. Furthermore, as the rectilinear length increases, the scaling laws of the Lyapunov exponent of the semi-stadium system are revealed and compared with those of the stadium system. The results suggest the potential application of the proposed model to simulate chaotic dynamics of acoustic ray in architectural enclosed systems. PMID:23556944

  18. The Research and Training Activities for the Joint Institute for Aeronautics and Acoustics

    NASA Technical Reports Server (NTRS)

    Cantwell, Brian

    1995-01-01

    This proposal requests continued support for the program of activities to be undertaken by the Ames-Stanford Joint Institute for Aeronautics and Acoustics during the period 1 Oct. 1995 - 30 Sept. 1996. The emphasis in this program is on training and research in experimental and computational methods with application to aerodynamics, acoustics and the important interactions between them. The program comprises activities in active flow control, Large Eddy Simulation of jet noise, flap aerodynamics and acoustics and high lift modeling studies. During the proposed period there will be a continued emphasis on the interaction between NASA Ames, Stanford University and Industry, particularly in connection with the high lift activities.

  19. Innovative system architecture for spatial volumetric acoustic seeing

    NASA Astrophysics Data System (ADS)

    Levin, Eugene; Sergeyev, Aleksandr V.

    2009-04-01

    Situational awareness is a critical issue for the modern battle and security systems improvement of which will increase human performance efficiency. There are multiple research project and development efforts based on omni-directional (fish-eye) electro-optical and other frequency sensor fusion systems implementing head-mounted visualization systems. However, the efficiency of these systems is limited by the human eye-brain system perception limitations. Humans are capable to naturally perceive the situations in front of them, but interpretation of omni-directional visual scenes increases the user's mental workload, increasing human fatigue and disorientation requiring more effort for object recognition. It is especially important to reduce this workload making rear scenes perception intuitive in battlefield situations where a combatant can be attacked from both directions. This paper describes an experimental model of the system fusion architecture of the Visual Acoustic Seeing (VAS) for representation spatial geometric 3D model in form of 3D volumetric sound. Current research in the area of auralization points to the possibility of identifying sound direction. However, for complete spatial perception it is necessary to identify the direction and the distance to an object by an expression of volumetric sound, we initially assume that the distance can be encoded by the sound frequency. The chain: object features -> sensor -> 3D geometric model-> auralization constitutes Volumetric Acoustic Seeing (VAS). Paper describes VAS experimental research for representing and perceiving spatial information by means of human hearing cues in more details.

  20. Active control of the acoustic boundary conditions of combustion test rigs

    NASA Astrophysics Data System (ADS)

    Bothien, Mirko R.; Moeck, Jonas P.; Oliver Paschereit, Christian

    2008-12-01

    In the design process of burners for gas turbines, new burner generations are generally tested in single or multi burner combustion test rigs. With these experiments, computational fluid dynamics, and finite element calculations, the burners' performance in the full-scale engine is sought to be predicted. Especially, information about the thermoacoustic behaviour and the emission characteristics is very important. As the thermoacoustics strongly depend on the acoustic boundary conditions of the system, it is obvious that test rig conditions should match, or be close to those of the full-scale engine. This is, however, generally not the case. Hence, if the combustion process in the test rig is stable at certain operating conditions, it may show unfavourable dynamics at the same conditions in the engine. In this work, a method is proposed which uses an active control scheme to manipulate the acoustic boundary conditions of the test rig. Using this method, the boundary conditions can be continuously modified, ranging from anechoic to fully reflecting in a broad frequency range. The concept is applied to an atmospheric combustion test rig with a swirl-stabilized burner. It is shown that the test rig's properties can be tuned to correspond to those of the full-scale engine. For example, the test rig length can be virtually extended, thereby introducing different resonance frequencies, without having to implement any hardware changes. Furthermore, the acoustic boundary condition can be changed to that of a choked flow without actually needing the flow to be choked.

  1. Acoustical evaluation of carbonized and activated cotton nonwovens.

    PubMed

    Jiang, N; Chen, J Y; Parikh, D V

    2009-12-01

    An activated carbon fiber nonwoven (ACF) was manufactured from a cotton nonwoven fabric. For the ACF acoustic application, a nonwoven composite of ACF with cotton nonwoven as a base layer was developed. Also produced were the composites of the cotton nonwoven base layer with a layer of glassfiber nonwoven, and the cotton nonwoven base layer with a layer of cotton fiber nonwoven. Their noise absorption coefficients and sound transmission loss were measured using the Brüel and Kjaer impedance tube instrument. Statistical significance of the differences between the composites was tested using the method of Duncan's grouping. The study concluded that the ACF composite exhibited a greater ability to absorb normal incidence sound waves than the composites with either glassfiber or cotton fiber. The analysis of sound transmission loss revealed that the three composites still obeyed the mass law of transmission loss. The composite with the surface layer of cotton fiber nonwoven possessed a higher fabric density and therefore showed a better sound insulation than the composites with glassfiber and ACF. PMID:19664919

  2. Development of a MEMS acoustic emission sensor system

    NASA Astrophysics Data System (ADS)

    Greve, David W.; Oppenheim, Irving J.; Wu, Wei; Wright, Amelia P.

    2007-04-01

    An improved multi-channel MEMS chip for acoustic emission sensing has been designed and fabricated in 2006 to create a device that is smaller in size, superior in sensitivity, and more practical to manufacture than earlier designs. The device, fabricated in the MUMPS process, contains four resonant-type capacitive transducers in the frequency range between 100 kHz and 500 kHz on a chip with an area smaller than 2.5 sq. mm. The completed device, with its circuit board, electronics, housing, and connectors, possesses a square footprint measuring 25 mm x 25 mm. The small footprint is an important attribute for an acoustic emission sensor, because multiple sensors must typically be arrayed around a crack location. Superior sensitivity was achieved by a combination of four factors: the reduction of squeeze film damping, a resonant frequency approximating a rigid body mode rather than a bending mode, a ceramic package providing direct acoustic coupling to the structural medium, and high-gain amplifiers implemented on a small circuit board. Manufacture of the system is more practical because of higher yield (lower unit costs) in the MUMPS fabrication task and because of a printed circuit board matching the pin array of the MEMS chip ceramic package for easy assembly and compactness. The transducers on the MEMS chip incorporate two major mechanical improvements, one involving squeeze film damping and one involving the separation of resonance modes. For equal proportions of hole area to plate area, a triangular layout of etch holes reduces squeeze film damping as compared to the conventional square layout. The effect is modeled analytically, and is verified experimentally by characterization experiments on the new transducers. Structurally, the transducers are plates with spring supports; a rigid plate would be the most sensitive transducer, and bending decreases the sensitivity. In this chip, the structure was designed for an order-of-magnitude separation between the first

  3. System And Method For Characterizing Voiced Excitations Of Speech And Acoustic Signals, Removing Acoustic Noise From Speech, And Synthesizi

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2006-04-25

    The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

  4. System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2004-03-23

    The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

  5. System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2006-02-14

    The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

  6. System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2006-08-08

    The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

  7. Fuel Line Based Acoustic Flame-Out Detection System

    NASA Technical Reports Server (NTRS)

    Puster, Richard L. (Inventor); Franke, John M. (Inventor)

    1997-01-01

    An acoustic flame-out detection system that renders a large high pressure combustor safe in the event of a flame-out and possible explosive reignition. A dynamic pressure transducer is placed in the fuel and detects the stabilizing fuel pressure oscillations, caused by the combustion process. An electric circuit converts the signal from the combustion vortices, and transmitted to the fuel flow to a series of pulses. A missing pulse detector counts the pulses and continuously resets itself. If three consecutive pulses are missing, the circuit closes the fuel valve. With fuel denied the combustor is shut down or restarted under controlled conditions.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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 to 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 cubic feet 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 in. supply line to their respective 4 in. 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.

  10. Acoustic dispersion in a two-dimensional dipole system

    SciTech Connect

    Golden, Kenneth I.; Kalman, Gabor J.; Donko, Zoltan; Hartmann, Peter

    2008-07-15

    We calculate the full density response function and from it the long-wavelength acoustic dispersion for a two-dimensional system of strongly coupled point dipoles interacting through a 1/r{sup 3} potential at arbitrary degeneracy. Such a system has no random-phase-approximation (RPA) limit and the calculation has to include correlations from the outset. We follow the quasilocalized charge (QLC) approach, accompanied by molecular-dynamics (MD) simulations. Similarly to what has been recently reported for the closely spaced classical electron-hole bilayer [G. J. Kalman et al., Phys. Rev. Lett. 98, 236801 (2007)] and in marked contrast to the RPA, we report a long-wavelength acoustic phase velocity that is wholly maintained by particle correlations and varies linearly with the dipole moment p. The oscillation frequency, calculated both in an extended QLC approximation and in the Singwi-Tosi-Land-Sjolander approximation [Phys. Rev. 176, 589 (1968)], is invariant in form over the entire classical to quantum domains all the way down to zero temperature. Based on our classical MD-generated pair distribution function data and on ground-state energy data generated by recent quantum Monte Carlo simulations on a bosonic dipole system [G. E. Astrakharchik et al., Phys. Rev. Lett. 98, 060405 (2007)], there is a good agreement between the QLC approximation kinetic sound speeds and the standard thermodynamic sound speeds in both the classical and quantum domains.

  11. Acoustic Predictions of Manned and Unmanned Rotorcraft Using the Comprehensive Analytical Rotorcraft Model for Acoustics (CARMA) Code System

    NASA Technical Reports Server (NTRS)

    Boyd, D. Douglas, Jr.; Burley, Casey L.; Conner, David A.

    2005-01-01

    The Comprehensive Analytical Rotorcraft Model for Acoustics (CARMA) is being developed under the Quiet Aircraft Technology Project within the NASA Vehicle Systems Program. The purpose of CARMA is to provide analysis tools for the design and evaluation of efficient low-noise rotorcraft, as well as support the development of safe, low-noise flight operations. The baseline prediction system of CARMA is presented and current capabilities are illustrated for a model rotor in a wind tunnel, a rotorcraft in flight and for a notional coaxial rotor configuration; however, a complete validation of the CARMA system capabilities with respect to a variety of measured databases is beyond the scope of this work. For the model rotor illustration, predicted rotor airloads and acoustics for a BO-105 model rotor are compared to test data from HART-II. For the flight illustration, acoustic data from an MD-520N helicopter flight test, which was conducted at Eglin Air Force Base in September 2003, are compared with CARMA full vehicle flight predictions. Predicted acoustic metrics at three microphone locations are compared for limited level flight and descent conditions. Initial acoustic predictions using CARMA for a notional coaxial rotor system are made. The effect of increasing the vertical separation between the rotors on the predicted airloads and acoustic results are shown for both aerodynamically non-interacting and aerodynamically interacting rotors. The sensitivity of including the aerodynamic interaction effects of each rotor on the other, especially when the rotors are in close proximity to one another is initially examined. The predicted coaxial rotor noise is compared to that of a conventional single rotor system of equal thrust, where both are of reasonable size for an unmanned aerial vehicle (UAV).

  12. Synthetic gauge flux and Weyl points in acoustic systems

    NASA Astrophysics Data System (ADS)

    Xiao, Meng; Chen, Wen-Jie; He, Wen-Yu; Chan, C. T.

    We consider acoustic systems comprising a honeycomb lattice in the xy plane and periodic along the z direction. As kz is a good quantum number here, for each fixed kz, this system can be treated as a reduced two-dimensional system. By engineering the interlayer coupling in the z-direction, we show that we can realize effective inversion symmetry breaking and synthetic staggered gauge flux in the reduced two-dimensional system. The realizations of chiral edge states for fixed values of kz are direct consequences of the staggered gauge flux. And we then show that the synthetic gauge flux is closely related to the Weyl points in the three-dimensional band structure. This work was supported by the Hong Kong Research Grants Council (Grant No. AoE/P-02/12).

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Acoustic communication in plant-animal interactions.

    PubMed

    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. PMID:27423052

  15. Effects of Systemic Hydration on Vocal Acoustics of 18- to 35-Year-Old Females

    ERIC Educational Resources Information Center

    Franca, Maria Claudia; Simpson, Kenneth O.

    2012-01-01

    The influence of body hydration and vocal acoustics was investigated in this study. Effects of two levels of hydration on objective measures of vocal acoustics were explored. In an attempt to reduce variability in the degree of systemic hydration and to induce a state of systemic dehydration, participants were instructed to refrain from ingestion…

  16. Detection of impulsive sources from an aerostat-based acoustic array data collection system

    NASA Astrophysics Data System (ADS)

    Prather, Wayne E.; Clark, Robert C.; Strickland, Joshua; Frazier, Wm. Garth; Singleton, Jere

    2009-05-01

    An aerostat based acoustic array data collection system was deployed at the NATO TG-53 "Acoustic Detection of Weapon Firing" Joint Field Experiment conducted in Bourges, France during the final two weeks of June 2008. A variety of impulsive sources including mortar, artillery, gunfire, RPG, and explosive devices were fired during the test. Results from the aerostat acoustic array will be presented against the entire range of sources.

  17. A Dual Communication and Imaging Underwater Acoustic System

    NASA Astrophysics Data System (ADS)

    Fu, Tricia C.

    A dual communication and imaging underwater acoustic system is proposed and developed throughout this dissertation. Due to the wide variation in underwater channel characteristics, the research here focuses more on robustness to multipath in the shallow underwater acoustic environment, rather than high bit-rate applications and signaling schemes. Lower bit-rate (in the hundreds of bits per second (bps) to low kbps), applications such as the transfer of ecological telemetry data, e.g. conductivity or temperature data, are the primary focus of this dissertation. The parallels between direct sequence spread spectrum in digital communication and pulse-echo with pulse compression in imaging, and channel estimation in communication and range profile estimation in imaging are drawn, leading to a unified communications and imaging platform. A digital communication algorithm for channel order and channel coefficient estimation and symbol demodulation using Matching Pursuit (MP) with Generalized Multiple Hypothesis Testing (GMHT) is implemented in programmable DSP in real time with field experiment results in varying underwater environments for the single receiver (Rx), single transmitter (Tx) case. The custom and off-the-shelf hardware used in the single receiver, single transmitter set of experiments are detailed as well. This work is then extended to the single-input multiple-output (SIMO) case, and then to the full multiple-input multiple-output (MIMO) case. The results of channel estimation are used for simple range profile imaging reconstructions. Successful simulated and experimental results for both transducer array configurations are presented and analyzed. Non-real-time symbol demodulation and channel estimation is performed using experimental data from a scaled testing environment. New hardware based on cost-effective fish-finder transducers for a 6 Rx--1 Tx and 6 Rx--4 Tx transducer array is detailed. Lastly, in an application that is neither communication nor

  18. Acoustic characteristics of externally blown flap systems with mixer nozzles

    NASA Technical Reports Server (NTRS)

    Goodykoontz, J. H.; Dorsch, R. G.; Wagner, J. M.

    1974-01-01

    Noise tests were conducted on a large scale, cold flow model of an engine-under-the-wing externally blown flap lift augmentation system employing a mixer nozzle. The mixer nozzle was used to reduce the flap impingement velocity and, consequently, try to attenuate the additional noise caused by the interaction between the jet exhaust and the wing flap. Results from the mixer nozzle tests are summarized and compared with the results for a conical nozzle. The comparison showed that with the mixer nozzle, less noise was generated when the trailing flap was in a typical landing setting (e.g., 60 deg). However, for a takeoff flap setting (20 deg), there was little or no difference in the acoustic characteristics when either the mixer or conical nozzle was used.

  19. Acoustic Filtration, Fractionation, and Mixing in Microfluidic Systems

    SciTech Connect

    Wang, A; Fisher, K

    2002-02-04

    This project is concerned with the research and development of a technique to manipulate small particles using acoustic energy coupled into a fluid filled plastic or glass sample chamber. These resulting miniaturized systems combine high functionality with an inexpensive, disposable sample chamber. Our approach to this problem is based on a combination of sophisticated modeling tools in conjunction with laboratory experiments. The design methodology is summarized in Figure 1. The process begins by investigating a wide range of device parameters using a one-dimensional analytical approximation. The results of these initial parameter studies are incorporated into a sophisticated three-dimensional multi-physics finite element code. From these simulations the optimized designs are prototyped and experimentally tested. The results of the experimental observations are then used to improve analytical approximations and the process is repeated as necessary.

  20. System for Manipulating Drops and Bubbles Using Acoustic Radiation Pressure

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C. (Inventor)

    1999-01-01

    The manipulation and control of drops of liquid and gas bubbles is achieved using high intensity acoustics in the form of and/or acoustic radiation pressure and acoustic streaming. generated by a controlled wave emission from a transducer. Acoustic radiation pressure is used to deploy or dispense drops into a liquid or a gas or bubbles into a liquid at zero or near zero velocity from the discharge end of a needle such as a syringe needle. Acoustic streaming is useful in manipulating the drop or bubble during or after deployment. Deployment and discharge is achieved by focusing the acoustic radiation pressure on the discharge end of the needle, and passing the acoustic waves through the fluid in the needle. through the needle will itself, or coaxially through the fluid medium surrounding the needle. Alternatively, the acoustic waves can be counter-deployed by focusing on the discharge end of the needle from a transducer axially aligned with the needle, but at a position opposite the needle, to prevent premature deployment of the drop or bubble. The acoustic radiation pressure can also be used for detecting the presence or absence of a drop or a bubble at the tip of a needle or for sensing various physical characteristics of the drop or bubble such as size or density.

  1. Space Launch System Scale Model Acoustic Test Ignition Overpressure Testing

    NASA Technical Reports Server (NTRS)

    Nance, Donald; Liever, Peter; Nielsen, Tanner

    2015-01-01

    The overpressure phenomenon is a transient fluid dynamic event occurring during rocket propulsion system ignition. This phenomenon results from fluid compression of the accelerating plume gas, subsequent rarefaction, and subsequent propagation from the exhaust trench and duct holes. The high-amplitude unsteady fluid-dynamic perturbations can adversely affect the vehicle and surrounding structure. Commonly known as ignition overpressure (IOP), this is an important design-to environment for the Space Launch System (SLS) that NASA is currently developing. Subscale testing is useful in validating and verifying the IOP environment. This was one of the objectives of the Scale Model Acoustic Test, conducted at Marshall Space Flight Center. The test data quantifies the effectiveness of the SLS IOP suppression system and improves the analytical models used to predict the SLS IOP environments. The reduction and analysis of the data gathered during the SMAT IOP test series requires identification and characterization of multiple dynamic events and scaling of the event waveforms to provide the most accurate comparisons to determine the effectiveness of the IOP suppression systems. The identification and characterization of the overpressure events, the waveform scaling, the computation of the IOP suppression system knockdown factors, and preliminary comparisons to the analytical models are discussed.

  2. Space Launch System Scale Model Acoustic Test Ignition Overpressure Testing

    NASA Technical Reports Server (NTRS)

    Nance, Donald K.; Liever, Peter A.

    2015-01-01

    The overpressure phenomenon is a transient fluid dynamic event occurring during rocket propulsion system ignition. This phenomenon results from fluid compression of the accelerating plume gas, subsequent rarefaction, and subsequent propagation from the exhaust trench and duct holes. The high-amplitude unsteady fluid-dynamic perturbations can adversely affect the vehicle and surrounding structure. Commonly known as ignition overpressure (IOP), this is an important design-to environment for the Space Launch System (SLS) that NASA is currently developing. Subscale testing is useful in validating and verifying the IOP environment. This was one of the objectives of the Scale Model Acoustic Test (SMAT), conducted at Marshall Space Flight Center (MSFC). The test data quantifies the effectiveness of the SLS IOP suppression system and improves the analytical models used to predict the SLS IOP environments. The reduction and analysis of the data gathered during the SMAT IOP test series requires identification and characterization of multiple dynamic events and scaling of the event waveforms to provide the most accurate comparisons to determine the effectiveness of the IOP suppression systems. The identification and characterization of the overpressure events, the waveform scaling, the computation of the IOP suppression system knockdown factors, and preliminary comparisons to the analytical models are discussed.

  3. Diversity of acoustic tracheal system and its role for directional hearing in crickets

    PubMed Central

    2013-01-01

    Background Sound localization in small insects can be a challenging task due to physical constraints in deriving sufficiently large interaural intensity differences (IIDs) between both ears. In crickets, sound source localization is achieved by a complex type of pressure difference receiver consisting of four potential sound inputs. Sound acts on the external side of two tympana but additionally reaches the internal tympanal surface via two external sound entrances. Conduction of internal sound is realized by the anatomical arrangement of connecting trachea. A key structure is a trachea coupling both ears which is characterized by an enlarged part in its midline (i.e., the acoustic vesicle) accompanied with a thin membrane (septum). This facilitates directional sensitivity despite an unfavorable relationship between wavelength of sound and body size. Here we studied the morphological differences of the acoustic tracheal system in 40 cricket species (Gryllidae, Mogoplistidae) and species of outgroup taxa (Gryllotalpidae, Rhaphidophoridae, Gryllacrididae) of the suborder Ensifera comprising hearing and non hearing species. Results We found a surprisingly high variation of acoustic tracheal systems and almost all investigated species using intraspecific acoustic communication were characterized by an acoustic vesicle associated with a medial septum. The relative size of the acoustic vesicle - a structure most crucial for deriving high IIDs - implies an important role for sound localization. Most remarkable in this respect was the size difference of the acoustic vesicle between species; those with a more unfavorable ratio of body size to sound wavelength tend to exhibit a larger acoustic vesicle. On the other hand, secondary loss of acoustic signaling was nearly exclusively associated with the absence of both acoustic vesicle and septum. Conclusion The high diversity of acoustic tracheal morphology observed between species might reflect different steps in the evolution

  4. Coherent active methods for applications in room acoustics.

    PubMed

    Guicking, D; Karcher, K; Rollwage, M

    1985-10-01

    An adjustment of reverberation time in rooms is often desired, even for low frequencies where passive absorbers fail. Among the active (electroacoustic) systems, incoherent ones permit lengthening of reverberation time only, whereas coherent active methods will allow sound absorption as well. A coherent-active wall lining consists of loudspeakers with microphones in front and adjustable control electronics. The microphones pick up the incident sound and drive the speakers in such a way that the reflection coefficient takes on prescribed values. An experimental device for the one-dimensional case allows reflection coefficients between almost zero and about 1.5 to be realized below 1000 Hz. The extension to three dimensions presents problems, especially by nearfield effects. Experiments with a 3 X 3 loudspeaker array and computer simulations proved that the amplitude reflection coefficient can be adjusted between 10% and 200% for sinusoidal waves at normal and oblique incidence. Future developments have to make the system work with broadband excitation and in more diffuse sound fields. It is also planned to combine the active reverberation control with active diffusion control. PMID:3840501

  5. A numerical study of active structural acoustic control in a stiffened, double wall cylinder

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.; Coats, T. J.; Lester, H. C.; Silcox, R. J.

    1994-01-01

    It is demonstrated that active structural acoustic control of complex structural/acoustic coupling can be numerically modeled using finite element and boundary element techniques in conjunction with an optimization procedure to calculate control force amplitudes. Appreciable noise reduction is obtained when the structure is excited at a structural resonance of the outer shell or an acoustic resonance of the inner cavity. Adding ring stiffeners as a connection between the inner and outer shells provides an additional structural transmission path to the interior cavity and coupled the modal behavior of the inner and outer shells. For the case of excitation at the structural resonance of the unstiffened outer shell, adding the stiffeners raises the structural resonance frequencies. The effectiveness of the control forces is reduced due to the off resonance structural response. For excitation at an acoustic cavity resonance, the controller effectiveness is enhanced.

  6. Acoustic monitoring method and system in laser-induced optical breakdown (LIOB)

    DOEpatents

    O'Donnell, Matthew; Ye, Jing Yong; Norris, Theodore B.; Baker, Jr., James R.; Balogh, Lajos P.; Milas, Susanne M.; Emelianov, Stanislav Y.; Hollman, Kyle W.

    2008-05-06

    An acoustic monitoring method and system in laser-induced optical breakdown (LIOB) provides information which characterize material which is broken down, microbubbles in the material, and/or the microenvironment of the microbubbles. In one embodiment of the invention, femtosecond laser pulses are focused just inside the surface of a volume of aqueous solution which may include dendrimer nanocomposite (DNC) particles. A tightly focused, high frequency, single-element ultrasonic transducer is positioned such that its focus coincides axially and laterally with this laser focus. When optical breakdown occurs, a microbubble forms and a shock or pressure wave is emitted (i.e., acoustic emission). In addition to this acoustic signal, the microbubble may be actively probed with pulse-echo measurements from the same transducer. After the microbubble forms, received pulse-echo signals have an extra pulse, describing the microbubble location and providing a measure of axial microbubble size. Wavefield plots of successive recordings illustrate the generation, growth, and collapse of microbubbles due to optical breakdown. These same plots can also be used to quantify LIOB thresholds.

  7. Resonant acoustic transducer system for a well drilling string

    DOEpatents

    Kent, William H.; Mitchell, Peter G.

    1981-01-01

    For use in transmitting acoustic waves propagated 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 resonant operation in the desired low frequency range.

  8. Resonant acoustic transducer system for a well drilling string

    DOEpatents

    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.

  9. O the Use of Modern Control Theory for Active Structural Acoustic Control.

    NASA Astrophysics Data System (ADS)

    Saunders, William Richard

    A modern control theory formulation of Active Structural Acoustic Control (ASAC) of simple structures radiating acoustic energy into light or heavy fluid mediums is discussed in this dissertation. ASAC of a baffled, simply-supported plate subject to mechanical disturbances is investigated. For the case of light fluid loading, a finite element modelling approach is used to extend previous ASAC design methods. Vibration and acoustic controllers are designed for the plate. Comparison of the controller performance shows distinct advantages of the ASAC method for minimizing radiated acoustic power. A novel approach to the modelling of the heavy fluid-loaded plate is developed here. Augmenting structural and acoustic dynamics using state vector formalism allows the design of both vibration and ASAC controllers for the fluid-loaded plate. This modern control approach to active structural acoustic control is unique in its ability to suppress both persistent and transient disturbances on a plate in a heavy fluid. Numerical simulations of the open-loop and closed-loop plate response are provided to support the theoretical developments.

  10. Manipulation of acoustic focusing with an active and configurable planar metasurface transducer

    NASA Astrophysics Data System (ADS)

    Zhao, Jiajun; Ye, Huapeng; Huang, Kun; Chen, Zhi Ning; Li, Baowen; Qiu, Cheng-Wei

    2014-09-01

    It has a pivotal role in medical science and in industry to concentrate the acoustic energy created with piezoelectric transducers (PTs) into a specific area. However, previous researches seldom consider the focal resolution, whose focal size is much larger than one wavelength. Furthermore, there is to date no such design method of PTs that allows a large degree of freedom to achieve designed focal patterns. Here, an active and configurable planar metasurface PT prototype is proposed to manipulate the acoustic focal pattern and the focal resolution freely. By suitably optimized ring configurations of the active metasurface PT, we demonstrate the manipulation of focal patterns in acoustic far fields, such as the designed focal needle and multi foci. Our method is also able to manipulate and improve the cross-sectional focal resolution from subwavelength to the extreme case: the deep sub-diffraction-limit resolution. Via the acoustic Rayleigh-Sommerfeld diffraction integral (RSI) cum the binary particle swarm optimization (BPSO), the free manipulation of focusing properties is achieved in acoustics for the first time. Our approach may offer more initiatives where the strict control of acoustic high-energy areas is demanding.

  11. Manipulation of acoustic focusing with an active and configurable planar metasurface transducer.

    PubMed

    Zhao, Jiajun; Ye, Huapeng; Huang, Kun; Chen, Zhi Ning; Li, Baowen; Qiu, Cheng-Wei

    2014-01-01

    It has a pivotal role in medical science and in industry to concentrate the acoustic energy created with piezoelectric transducers (PTs) into a specific area. However, previous researches seldom consider the focal resolution, whose focal size is much larger than one wavelength. Furthermore, there is to date no such design method of PTs that allows a large degree of freedom to achieve designed focal patterns. Here, an active and configurable planar metasurface PT prototype is proposed to manipulate the acoustic focal pattern and the focal resolution freely. By suitably optimized ring configurations of the active metasurface PT, we demonstrate the manipulation of focal patterns in acoustic far fields, such as the designed focal needle and multi foci. Our method is also able to manipulate and improve the cross-sectional focal resolution from subwavelength to the extreme case: the deep sub-diffraction-limit resolution. Via the acoustic Rayleigh-Sommerfeld diffraction integral (RSI) cum the binary particle swarm optimization (BPSO), the free manipulation of focusing properties is achieved in acoustics for the first time. Our approach may offer more initiatives where the strict control of acoustic high-energy areas is demanding. PMID:25174409

  12. Manipulation of acoustic focusing with an active and configurable planar metasurface transducer

    PubMed Central

    Zhao, Jiajun; Ye, Huapeng; Huang, Kun; Chen, Zhi Ning; Li, Baowen; Qiu, Cheng-Wei

    2014-01-01

    It has a pivotal role in medical science and in industry to concentrate the acoustic energy created with piezoelectric transducers (PTs) into a specific area. However, previous researches seldom consider the focal resolution, whose focal size is much larger than one wavelength. Furthermore, there is to date no such design method of PTs that allows a large degree of freedom to achieve designed focal patterns. Here, an active and configurable planar metasurface PT prototype is proposed to manipulate the acoustic focal pattern and the focal resolution freely. By suitably optimized ring configurations of the active metasurface PT, we demonstrate the manipulation of focal patterns in acoustic far fields, such as the designed focal needle and multi foci. Our method is also able to manipulate and improve the cross-sectional focal resolution from subwavelength to the extreme case: the deep sub-diffraction-limit resolution. Via the acoustic Rayleigh-Sommerfeld diffraction integral (RSI) cum the binary particle swarm optimization (BPSO), the free manipulation of focusing properties is achieved in acoustics for the first time. Our approach may offer more initiatives where the strict control of acoustic high-energy areas is demanding. PMID:25174409

  13. Baseline acoustic levels of the NASA Active Noise Control Fan rig

    NASA Technical Reports Server (NTRS)

    Sutliff, Daniel L.; Heidelberg, Laurence J.; Elliott, David M.; Nallasamy, M.

    1996-01-01

    Extensive measurements of the spinning acoustic mode structure in the NASA 48 inch Active Noise Control Fan (ANCF) test rig have been taken. A continuously rotating microphone rake system with a least-squares data reduction technique was employed to measure these modes in the inlet and exhaust. Farfield directivity patterns in an anechoic environment were also measured at matched corrected rotor speeds. Several vane counts and spacings were tested over a range of rotor speeds. The Eversman finite element radiation code was run with the measured in-duct modes as input and the computed farfield results were compared to the experimentally measured directivity pattern. The experimental data show that inlet spinning mode measurements can be made very accurately. Exhaust mode measurements may have wake interference, but the least-squares reduction does a good job of rejecting the non-acoustic pressure. The Eversman radiation code accurately extrapolates the farfield levels and directivity pattern when all in-duct modes are included.

  14. Underwater acoustic positioning system for the SMO and KM3NeT - Italia projects

    SciTech Connect

    Viola, S.; Barbagallo, G.; Cacopardo, G.; Calí, C.; Cocimano, R.; Coniglione, R.; Costa, M.; Cuttone, G.; D'Amato, C.; D'Amato, V.; D'Amico, A.; De Luca, V.; Del Tevere, F.; Distefano, C.; Ferrera, F.; Gmerk, A.; Grasso, R.; Imbesi, M.; Larosa, G.; Lattuada, D.; and others

    2014-11-18

    In the underwater neutrino telescopes, the positions of the Cherenkov light sensors and their movements must be known with an accuracy of few tens of centimetres. In this work, the activities of the SMO and KM3NeT-Italia teams for the development of an acoustic positioning system for KM3NeT-Italia project are presented. The KM3NeT-Italia project foresees the construction, within two years, of 8 towers in the view of the several km{sup 3}-scale neutrino telescope KM3NeT.

  15. A novel acoustic approach for the characterization of granular activated carbons used in the rum production.

    PubMed

    Crespo Sariol, Harold; Yperman, Jan; Brito Sauvanell, Ángel; Carleer, Robert; Campa, José Navarro; Gryglewicz, Grazyna

    2016-08-01

    Acoustic analysis and sound patterns recognition techniques have been widely used in many branches of science, however; almost none focused on the characterization of granular activated carbon. A new methodology has been developed in order to characterize activated carbon based on the dynamic analysis in audible spectra of the sound's relative amplitude power produced by water flooded on granular activated carbon. A home-build recording set-up and management of acoustic measurements have been presented and correlated with the results of porous structure of carbons characterized by N2 adsorption. Five samples of granular activated carbons used in the rum production of different exhausted level have been evaluated by both methods. Parameters as the BET surface area and total pore volume showed a satisfactory correlation with acoustic measurement data when the signal is processed at 1000Hz. Three frequencies components of the produced sound were analyzed and related with the porous characteristics. The found relationship gives the possibility to predict and calculate textural parameters of granular activated carbons applying the acoustic technique. This methodology approach opens possibilities in using acoustic experiments for the characterization of high-porosity materials and to determine their exhausted level. PMID:27135186

  16. Towards an Automated Acoustic Detection System for Free Ranging Elephants

    PubMed Central

    Zeppelzauer, Matthias; Hensman, Sean; Stoeger, Angela S.

    2015-01-01

    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. PMID:25983398

  17. Field performance of an acoustic scour-depth monitoring system

    USGS Publications Warehouse

    Mason, Jr., Robert R.; Sheppard, D. Max

    1994-01-01

    The Herbert C. Bonner Bridge over Oregon Inlet serves as the only land link between Bodie and Hatteras Islands, part of the Outer Banks of North Carolina. Periodic soundings over the past 30 years have documented channel migration, local scour, and deposition at several pilings that support the bridge. In September 1992, a data-collection system was installed to permit the off-site monitoring of scour at 16 bridge pilings. The system records channel-bed elevations at 15-minute intervals and transmits the data to a satellite receiver. A cellular phone connection also permits downloading and reviewing of the data as they are being collected. A digitally recording, acoustic fathometer is the main component of the system. In November 1993, current velocity, water-surface elevation, wave characteristics, and water temperature measuring instruments were also deployed at the site. Several performance problems relating to the equipment and to the harsh marine environment have not been resolved, but the system has collected and transmitted reliable scour-depth and water-level data.

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

    DOEpatents

    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.

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

    DOEpatents

    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.

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

    DOEpatents

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

    1998-07-28

    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.

  1. Improving acoustic streaming effects in fluidic systems by matching SU-8 and polydimethylsiloxane layers.

    PubMed

    Catarino, S O; Minas, G; Miranda, J M

    2016-07-01

    This paper reports the use of acoustic waves for promoting and improving streaming in tridimensional polymethylmethacrylate (PMMA) cuvettes of 15mm width×14mm height×2.5mm thickness. The acoustic waves are generated by a 28μm thick poly(vinylidene fluoride) - PVDF - piezoelectric transducer in its β phase, actuated at its resonance frequency: 40MHz. The acoustic transmission properties of two materials - SU-8 and polydimethylsiloxane (PDMS) - were numerically compared. It was concluded that PDMS inhibits, while SU-8 allows, the transmission of the acoustic waves to the propagation medium. Therefore, by simulating the acoustic transmission properties of different materials, it is possible to preview the acoustic behavior in the fluidic system, which allows the optimization of the best layout design, saving costs and time. This work also presents a comparison between numerical and experimental results of acoustic streaming obtained with that β-PVDF transducer in the movement and in the formation of fluid recirculation in tridimensional closed domains. Differences between the numerical and experimental results are credited to the high sensitivity of acoustic streaming to the experimental conditions and to limitations of the numerical method. The reported study contributes for the improvement of simulation models that can be extremely useful for predicting the acoustic effects of new materials in fluidic devices, as well as for optimizing the transducers and matching layers positioning in a fluidic structure. PMID:27044029

  2. Acoustic asymmetric transmission based on time-dependent dynamical scattering

    PubMed Central

    Wang, Qing; Yang, Yang; Ni, Xu; Xu, Ye-Long; Sun, Xiao-Chen; Chen, Ze-Guo; Feng, Liang; Liu, Xiao-ping; Lu, Ming-Hui; Chen, Yan-Feng

    2015-01-01

    An acoustic asymmetric transmission device exhibiting unidirectional transmission property for acoustic waves is extremely desirable in many practical scenarios. Such a unique property may be realized in various configurations utilizing acoustic Zeeman effects in moving media as well as frequency-conversion in passive nonlinear acoustic systems and in active acoustic systems. Here we demonstrate a new acoustic frequency conversion process in a time-varying system, consisting of a rotating blade and the surrounding air. The scattered acoustic waves from this time-varying system experience frequency shifts, which are linearly dependent on the blade’s rotating frequency. Such scattering mechanism can be well described theoretically by an acoustic linear time-varying perturbation theory. Combining such time-varying scattering effects with highly efficient acoustic filtering, we successfully develop a tunable acoustic unidirectional device with 20 dB power transmission contrast ratio between two counter propagation directions at audible frequencies. PMID:26038886

  3. 78 FR 19652 - Takes of Marine Mammals Incidental to Specified Activities; Office of Naval Research Acoustic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-02

    ...NMFS has received an application from the U.S. Navy's Office of Naval Research (ONR) for an Incidental Harassment Authorization (IHA) to take marine mammals, by harassment, incidental to conducting Acoustic Technology Experiments (ATE) in the western North Pacific Ocean. The Navy's activities are considered military readiness activities pursuant to the Marine Mammal Protection Act (MMPA), as......

  4. Synchronous behaviour of cetaceans observed with active acoustics

    NASA Astrophysics Data System (ADS)

    Godø, Olav Rune; Sivle, Lise Doksæter; Patel, Ruben; Torkelsen, Terje

    2013-12-01

    Scientific split-beam echosounders are sensitive instruments for observing biomass densities and individual behaviour. Earlier studies have demonstrated that these instruments can be used to study diving behaviour of cetaceans. In this paper, we go into more detail about the recorded signal to see if and how acoustic split-beam data can be used to extract information about synchronous behaviour and other species related characteristics. Data of several cetacean individuals were collected by a moored echosounder pinging upwards from about 900 m in the Charlie Gibbs Fracture Zone. In this paper, we discuss methodological issues associated with using split-beam tracking of large marine animals. Further we demonstrate that target tracking of cetaceans can be used to study solo dives as well as behavioural synchrony. We also show that paired signals can easily be interpreted as false synchrony due to the size of the animals. In such cases a rough estimate of the diameter, and hence size, of the animals can be estimated. We emphasise on four examples that clarify methodological challenges including synchronous swimmers as well as large single cetaceans that might be interpreted as two synchronous swimmers. The applied technology requires that the animals remain in a narrow acoustic beam for long enough time to extract behavioural information. The technology can be improved by developing automatic tracking of cetaceans with a steerable transducer. This will substantially increase the search volume and enable tracking of cetaceans over longer periods and thus, produce more realistic information about the whale behaviour.

  5. Online Damage Detection on Metal and Composite Space Structures by Active and Passive Acoustic Methods

    NASA Astrophysics Data System (ADS)

    Scheerer, M.; Cardone, T.; Rapisarda, A.; Ottaviano, S.; Ftancesconi, D.

    2012-07-01

    In the frame of ESA funded programme Future Launcher Preparatory Programme Period 1 “Preparatory Activities on M&S”, Aerospace & Advanced Composites and Thales Alenia Space-Italia, have conceived and tested a structural health monitoring approach based on integrated Acoustic Emission - Active Ultrasound Damage Identification. The monitoring methods implemented in the study are both passive and active methods and the purpose is to cover large areas with a sufficient damage size detection capability. Two representative space sub-structures have been built and tested: a composite overwrapped pressure vessel (COPV) and a curved, stiffened Al-Li panel. In each structure, typical critical damages have been introduced: delaminations caused by impacts in the COPV and a crack in the stiffener of the Al-Li panel which was grown during a fatigue test campaign. The location and severity of both types of damages have been successfully assessed online using two commercially available systems: one 6 channel AE system from Vallen and one 64 channel AU system from Acellent.

  6. Evaluation of multiple-frequency, active and passive acoustics as surrogates for bedload transport

    USGS Publications Warehouse

    Wood, Molly S.; Fosness, Ryan L.; Pachman, Gregory; Lorang, Mark; Tonolla, Diego

    2015-01-01

    The use of multiple-frequency, active acoustics through deployment of acoustic Doppler current profilers (ADCPs) shows potential for estimating bedload in selected grain size categories. The U.S. Geological Survey (USGS), in cooperation with the University of Montana (UM), evaluated the use of multiple-frequency, active and passive acoustics as surrogates for bedload transport during a pilot study on the Kootenai River, Idaho, May 17-18, 2012. Four ADCPs with frequencies ranging from 600 to 2000 kHz were used to measure apparent moving bed velocities at 20 stations across the river in conjunction with physical bedload samples. Additionally, UM scientists measured the sound frequencies of moving particles with two hydrophones, considered passive acoustics, along longitudinal transects in the study reach. Some patterns emerged in the preliminary analysis which show promise for future studies. Statistically significant relations were successfully developed between apparent moving bed velocities measured by ADCPs with frequencies 1000 and 1200 kHz and bedload in 0.5 to 2.0 mm grain size categories. The 600 kHz ADCP seemed somewhat sensitive to the movement of gravel bedload in the size range 8.0 to 31.5 mm, but the relation was not statistically significant. The passive hydrophone surveys corroborated the sample results and could be used to map spatial variability in bedload transport and to select a measurement cross-section with moving bedload for active acoustic surveys and physical samples.

  7. Acoustic Resonance Spectroscopy (ARS) Munition Classification System enhancements. Final report

    SciTech Connect

    Vela, O.A.; Huggard, J.C.

    1997-09-18

    Acoustic Resonance Spectroscopy (ARS) is a non-destructive evaluation technology developed at the Los Alamos National Laboratory (LANL). This technology has resulted in three generations of instrumentation, funded by the Defense Special Weapons Agency (DSWA), specifically designed for field identification of chemical weapon (CW) munitions. Each generation of ARS instrumentation was developed with a specific user in mind. The ARS1OO was built for use by the U.N. Inspection Teams going into Iraq immediately after the Persian Gulf War. The ARS200 was built for use in the US-Russia Bilateral Chemical Weapons Treaty (the primary users for this system are the US Onsite Inspection Agency (OSIA) and their Russian counterparts). The ARS300 was built with the requirements of the Organization for the Prohibition of Chemical Weapons (OPCW) in mind. Each successive system is an improved version of the previous system based on learning the weaknesses of each and, coincidentally, on the fact that more time was available to do a requirements analysis and the necessary engineering development. The ARS300 is at a level of development that warrants transferring the technology to a commercial vendor. Since LANL will supply the computer software to the selected vendor, it is possible for LANL to continue to improve the decision algorithms, add features where necessary, and adjust the user interface before the final transfer occurs. This paper describes the current system, ARS system enhancements, and software enhancements. Appendices contain the Operations Manual (software Version 3.01), and two earlier reports on enhancements.

  8. Direct-field acoustic testing of a flight system : logistics, challenges, and results.

    SciTech Connect

    Stasiunas, Eric Carl; Gurule, David Joseph; Babuska, Vit; Skousen, Troy J.

    2010-10-01

    Before a spacecraft can be considered for launch, it must first survive environmental testing that simulates the launch environment. Typically, these simulations include vibration testing performed using an electro-dynamic shaker. For some spacecraft however, acoustic excitation may provide a more severe loading environment than base shaker excitation. Because this was the case for a Sandia Flight System, it was necessary to perform an acoustic test prior to launch in order to verify survival due to an acoustic environment. Typically, acoustic tests are performed in acoustic chambers, but because of scheduling, transportation, and cleanliness concerns, this was not possible. Instead, the test was performed as a direct field acoustic test (DFAT). This type of test consists of surrounding a test article with a wall of speakers and controlling the acoustic input using control microphones placed around the test item, with a closed-loop control system. Obtaining the desired acoustic input environment - proto-flight random noise input with an overall sound pressure level (OASPL) of 146.7 dB-with this technique presented a challenge due to several factors. An acoustic profile with this high OASPL had not knowingly been obtained using the DFAT technique prior to this test. In addition, the test was performed in a high-bay, where floor space and existing equipment constrained the speaker circle diameter. And finally, the Flight System had to be tested without contamination of the unit, which required a contamination bag enclosure of the test unit. This paper describes in detail the logistics, challenges, and results encountered while performing a high-OASPL, direct-field acoustic test on a contamination-sensitive Flight System in a high-bay environment.

  9. Developing a system for blind acoustic source localization and separation

    NASA Astrophysics Data System (ADS)

    Kulkarni, Raghavendra

    This dissertation presents innovate methodologies for locating, extracting, and separating multiple incoherent sound sources in three-dimensional (3D) space; and applications of the time reversal (TR) algorithm to pinpoint the hyper active neural activities inside the brain auditory structure that are correlated to the tinnitus pathology. Specifically, an acoustic modeling based method is developed for locating arbitrary and incoherent sound sources in 3D space in real time by using a minimal number of microphones, and the Point Source Separation (PSS) method is developed for extracting target signals from directly measured mixed signals. Combining these two approaches leads to a novel technology known as Blind Sources Localization and Separation (BSLS) that enables one to locate multiple incoherent sound signals in 3D space and separate original individual sources simultaneously, based on the directly measured mixed signals. These technologies have been validated through numerical simulations and experiments conducted in various non-ideal environments where there are non-negligible, unspecified sound reflections and reverberation as well as interferences from random background noise. Another innovation presented in this dissertation is concerned with applications of the TR algorithm to pinpoint the exact locations of hyper-active neurons in the brain auditory structure that are directly correlated to the tinnitus perception. Benchmark tests conducted on normal rats have confirmed the localization results provided by the TR algorithm. Results demonstrate that the spatial resolution of this source localization can be as high as the micrometer level. This high precision localization may lead to a paradigm shift in tinnitus diagnosis, which may in turn produce a more cost-effective treatment for tinnitus than any of the existing ones.

  10. Ultrasonic database development for the acoustic inspection device: the velocity-attenuation measurement system (VAMS)

    NASA Astrophysics Data System (ADS)

    Diaz, Aaron A.; Burghard, Brion J.; Valencia, Juan D.; Samuel, Todd J.

    2004-07-01

    The inspection of sealed containers is a critical task for personnel charged with enforcing government policies, maintaining public safety, and ensuring national security. The Pacific Northwest National Laboratory (PNNL) has developed a portable, handheld acoustic inspection device (AID) that provides non-invasive container interrogation and material identification capabilities. The AID technology has been deployed worldwide and user"s are providing feedback and requesting additional capabilities and functionality. Recently, PNNL has developed a laboratory-based system for automated, ultrasonic characterization of fluids to support database development for the AID. Using pulse-echo ultrasound, ultrasonic pulses are launched into a container or bulk-solid commodity. The return echoes from these pulses are analyzed in terms of time-of-flight and frequency content (as a function of temperature) to extract physical property measurements (acoustic velocity and attenuation) of the material under test. These measured values are then compared to a tailored database of materials and fluids property data acquired using the Velocity-Attenuation Measurement System (VAMS). This bench-top platform acquires key ultrasonic property measurements as a function of temperature and frequency. This paper describes the technical basis for operation of the VAMS, recent enhancements to the measurement algorithms for both the VAMS and AID technologies, and new measurement data from laboratory testing and performance demonstration activities. Applications for homeland security and counterterrorism, law enforcement, drug-interdiction and fuel transportation compliance activities will be discussed.

  11. Broadband time reversed acoustic focusing and steering system

    NASA Astrophysics Data System (ADS)

    Sutin, Alexander; Sarvazyan, Armen; Montaldo, Gabriel; Palacio, Delphine; Bercoff, Jeremy; Tanter, Mickael; Fink, Mathias

    2001-05-01

    We present results of experimental testing and theoretical modeling of a time reversal acoustic (TRA) focusing system based on a multifaceted aluminum resonator with 15 piezoceramic transducers glued to the resonator facets. One of the facets of the resonator, a pentagon with characteristic dimension of about 30 mm, was submerged into a water tank and served as a virtual phased array which provided ultrasound focusing and beam steering in a wide frequency band (0.7-3 MHz). Ultrasonic pulses with different carrier frequencies and various complex waveforms were focused; the focal length was varied in the range of 10-55 mm and the focused beam was steered in a range of angles of +/-60 deg. The amplitude of the signal in the focal region reached 40 MPa. A theoretical model was based on an assumption that the radiating part of the resonator works as a phase conjugation screen for a spherical wave radiated from the focal point. Theoretical dependencies of the field structure on the position of the focus point and ultrasound frequency are in a good agreement with experimental results. TRA based focusing of ultrasound has numerous applications in medical diagnostics, surgery and therapy. [Work supported by NIH grant.

  12. Juvenile Salmon Acoustic Telemetry System Transmitter Downsize Assessment

    SciTech Connect

    Carlson, Thomas J.; Myjak, Mitchell J.

    2010-04-30

    At the request of the U.S. Army Corps of Engineers, Portland District, researchers from Pacific Northwest National Laboratory investigated the use of an application-specific integrated circuit (ASIC) to reduce the weight and volume of Juvenile Salmon Acoustic Telemetry System (JSATS) transmitters while retaining current functionality. Review of the design of current JSATS transmitters identified components that could be replaced by an ASIC while retaining the function of the current transmitter and offering opportunities to extend function if desired. ASIC design alternatives were identified that could meet transmitter weight and volume targets of 200 mg and 100 mm3. If alternatives to the cylindrical batteries used in current JSATS transmitters can be identified, it could be possible to implant ASIC-based JSATS transmitters by injection rather than surgery. Using criteria for the size of fish suitable for surgical implantation of current JSATS transmitters, it was concluded that fish as small as 70 mm in length could be implanted with an ASIC-based transmitter, particularly if implantation by injection became feasible.

  13. Broadband control of plate radiation using a piezoelectric, double-amplifier active-skin and structural acoustic sensing

    PubMed

    Johnson; Fuller

    2000-02-01

    The potential of a piezoelectric, double-amplifier active-skin with structural acoustic sensing (SAS) is demonstrated for the reduction of broadband acoustic radiation from a clamped, aluminum plate. The active-skin is a continuous covering of the vibrating portions of the plate with active, independently controllable piezoelectric, double-amplifier elements and is designed to affect control by altering the continuous structural radiation impedance rather than structural vibration. In simulation, acoustic models are sought for the primary and secondary sources that incorporate finite element methods. Simulation indicates that a total radiated power attenuation in excess of 10 dB may be achieved between 250 and 750 Hz with microphone error sensing, while under SAS the radiated power is reduced by nearly 8 dB in the same frequency range. In experiment, the adaptive feed forward filtered-x LMS (least mean square) algorithm, implemented on a Texas Instruments C40 DSP, was used in conjunction with the 6I6O control system. With microphone error sensing, 11.8-dB attenuation was achieved in the overall radiated power between 175 and 600 Hz, while inclusion of SAS resulted in a 7.3-dB overall power reduction in this frequency band. PMID:10687697

  14. Feature extraction from time domain acoustic signatures of weapons systems fire

    NASA Astrophysics Data System (ADS)

    Yang, Christine; Goldman, Geoffrey H.

    2014-06-01

    The U.S. Army is interested in developing algorithms to classify weapons systems fire based on their acoustic signatures. To support this effort, an algorithm was developed to extract features from acoustic signatures of weapons systems fire and applied to over 1300 signatures. The algorithm filtered the data using standard techniques then estimated the amplitude and time of the first five peaks and troughs and the location of the zero crossing in the waveform. The results were stored in Excel spreadsheets. The results are being used to develop and test acoustic classifier algorithms.

  15. Optimization of Concurrent Deployments of the Juvenile Salmon Acoustic Telemetry System and Other Hydroacoustic Equipment at John Day Dam

    SciTech Connect

    Ploskey, Gene R.; Hughes, James S.; Khan, Fenton; Kim, Jina; Lamarche, Brian L.; Johnson, Gary E.; Choi, Eric Y.; Faber, Derrek M.; Wilberding, Matthew C.; Deng, Zhiqun; Weiland, Mark A.; Zimmerman, Shon A.; Fischer, Eric S.; Cushing, Aaron W.

    2008-09-01

    The purpose of this report is to document the results of the acoustic optimization study conducted at John Day Dam during January and February 2008. The goal of the study was to optimize performance of the Juvenile Salmon Acoustic Telemetry System (JSATS) by determining deployment and data acquisition methods to minimize electrical and acoustic interference from various other acoustic sampling devices. Thereby, this would allow concurrent sampling by active and passive acoustic methods during the formal evaluations of the prototype surface flow outlets at the dam during spring and summer outmigration seasons for juvenile salmonids. The objectives for the optimization study at John Day Dam were to: 1. Design and test prototypes and provide a total needs list of pipes and trolleys to deploy JSATS hydrophones on the forebay face of the powerhouse and spillway. 2. Assess the effect on mean percentage decoded of JSATS transmissions from tags arrayed in the forebay and detected on the hydrophones by comparing: turbine unit OFF vs. ON; spill bay OPEN vs. CLOSED; dual frequency identification sonar (DIDSON) and acoustic Doppler current profiler (ADCP) both OFF vs. ON at a spill bay; and, fixed-aspect hydroacoustic system OFF vs. ON at a turbine unit and a spill bay. 3. Determine the relationship between fixed-aspect hydroacoustic transmit level and mean percentage of JSATS transmissions decoded. The general approach was to use hydrophones to listen for transmissions from JSATS tags deployed in vertical arrays in a series perpendicular to the face of the dam. We used acoustic telemetry equipment manufactured by Technologic and Sonic Concepts. In addition, we assessed old and new JSATS signal detectors and decoders and two different types of hydrophone baffling. The optimization study consisted of a suite of off/on tests. The primary response variable was mean percentage of tag transmissions decoded. We found that there was no appreciable adverse effect on mean percentage

  16. Time and timing in the acoustic recognition system of crickets

    PubMed Central

    Hennig, R. Matthias; Heller, Klaus-Gerhard; Clemens, Jan

    2014-01-01

    The songs of many insects exhibit precise timing as the result of repetitive and stereotyped subunits on several time scales. As these signals encode the identity of a species, time and timing are important for the recognition system that analyzes these signals. Crickets are a prominent example as their songs are built from sound pulses that are broadcast in a long trill or as a chirped song. This pattern appears to be analyzed on two timescales, short and long. Recent evidence suggests that song recognition in crickets relies on two computations with respect to time; a short linear-nonlinear (LN) model that operates as a filter for pulse rate and a longer integration time window for monitoring song energy over time. Therefore, there is a twofold role for timing. A filter for pulse rate shows differentiating properties for which the specific timing of excitation and inhibition is important. For an integrator, however, the duration of the time window is more important than the precise timing of events. Here, we first review evidence for the role of LN-models and integration time windows for song recognition in crickets. We then parameterize the filter part by Gabor functions and explore the effects of duration, frequency, phase, and offset as these will correspond to differently timed patterns of excitation and inhibition. These filter properties were compared with known preference functions of crickets and katydids. In a comparative approach, the power for song discrimination by LN-models was tested with the songs of over 100 cricket species. It is demonstrated how the acoustic signals of crickets occupy a simple 2-dimensional space for song recognition that arises from timing, described by a Gabor function, and time, the integration window. Finally, we discuss the evolution of recognition systems in insects based on simple sensory computations. PMID:25161622

  17. Parallel feedback active noise control of MRI acoustic noise with signal decomposition using hybrid RLS-NLMS adaptive algorithms.

    PubMed

    Ganguly, Anshuman; Krishna Vemuri, Sri Hari; Panahi, Issa

    2014-01-01

    This paper presents a cost-effective adaptive feedback Active Noise Control (FANC) method for controlling functional Magnetic Resonance Imaging (fMRI) acoustic noise by decomposing it into dominant periodic components and residual random components. Periodicity of fMRI acoustic noise is exploited by using linear prediction (LP) filtering to achieve signal decomposition. A hybrid combination of adaptive filters-Recursive Least Squares (RLS) and Normalized Least Mean Squares (NLMS) are then used to effectively control each component separately. Performance of the proposed FANC system is analyzed and Noise attenuation levels (NAL) up to 32.27 dB obtained by simulation are presented which confirm the effectiveness of the proposed FANC method. PMID:25570676

  18. A review of underwater acoustic systems and methods for locating objects lost at sea

    NASA Technical Reports Server (NTRS)

    Lovelady, R. W.; Ferguson, R. L.

    1983-01-01

    Information related to the location of objects lost at sea is presented. Acoustic devices attached to an object prior to being transported is recommended as a homing beacon. Minimum requirements and some environmental constraints are defined. Methods and procedures for search and recovery are also discussed. Both an interim system and a more advanced system are outlined. Controlled acoustic emission to enhance security is the theme followed.

  19. The Research and Training Activities for the Joint Institute for Aeronautics and Acoustics

    NASA Technical Reports Server (NTRS)

    Cantwell, Brian

    1996-01-01

    This proposal requests continued support for the program of activities to be undertaken by the Ames-Stanford Joint Institute for Aeronautics and Acoustics during the one-year period October 1, 1996 to September 30, 1997. The emphasis in this program is on training and research in experimental and computational methods with application to aerodynamics, acoustics and the important interactions between them. The program comprises activities in active flow control, Large Eddy Simulation of jet noise, flap aerodynamics and acoustics, high lift modeling studies and luminescent paint applications. During the proposed period there will be a continued emphasis on the interaction between NASA Ames, Stanford University and Industry, particularly in connection with the noise and high lift activities. The program will be conducted within the general framework of the Memorandum of Understanding (1976) establishing the Institute, as updated in 1993. As outlined in the agreement, the purposes of the institute include the following: To conduct basic and applied research. To promote joint endeavors between Center scientists and those in the academic community To provide training to graduate students in specialized areas of aeronautics and acoustics through participation in the research programs of the Institute. To provide opportunities for Post-Doctoral Fellows to collaborate in research programs of the Institute. To disseminate information about important aeronautical topics and to enable scientists and engineers of the Center to stay abreast of new advances through symposia, seminars and publications.

  20. The Research and Training Activities for the Joint Institute for Aeronautics and Acoustics

    NASA Technical Reports Server (NTRS)

    Cantwell, Brian

    1997-01-01

    This proposal requests continued support for the program of activities to be undertaken by the Ames-Stanford Joint Institute for Aeronautics and Acoustics during the one-year period October 1, 1997 to September 30, 1998. The emphasis in this program is on training and research in experimental and computational methods with application to aerodynamics, acoustics and the important interactions between them. The program comprises activities in active flow control, Large Eddy Simulation of jet noise, flap aerodynamics and acoustics, high lift modeling studies and luminescent paint applications. During the proposed period there will be a continued emphasis on the interaction between NASA Ames, Stanford University and Industry, particularly in connection with the noise and high lift activities. The program will be conducted within the general framework of the Memorandum of Understanding (1976) establishing the Institute, as updated in 1993. As outlined in the agreement, the purposes of the Institute include the following: (1) To conduct basic and applied research; (2) to promote joint endeavors between Center scientists and those in the academic community; (3) to provide training to graduate students in specialized areas of aeronautics and acoustics through participation in the research programs of the Institute; (4) to provide opportunities for Post-Doctoral Fellows to collaborate in research programs of the Institute; and (5) to disseminate information about important aeronautical topics and to enable scientists and engineers of the Center to stay abreast of new advances through symposia, seminars and publications.

  1. Wideband acoustic activation and detection of droplet vaporization events using a capacitive micromachined ultrasonic transducer.

    PubMed

    Novell, Anthony; Arena, Christopher B; Oralkan, Omer; Dayton, Paul A

    2016-06-01

    An ongoing challenge exists in understanding and optimizing the acoustic droplet vaporization (ADV) process to enhance contrast agent effectiveness for biomedical applications. Acoustic signatures from vaporization events can be identified and differentiated from microbubble or tissue signals based on their frequency content. The present study exploited the wide bandwidth of a 128-element capacitive micromachined ultrasonic transducer (CMUT) array for activation (8 MHz) and real-time imaging (1 MHz) of ADV events from droplets circulating in a tube. Compared to a commercial piezoelectric probe, the CMUT array provides a substantial increase of the contrast-to-noise ratio. PMID:27369143

  2. Exploration of amphoteric and negative refraction imaging of acoustic sources via active metamaterials

    NASA Astrophysics Data System (ADS)

    Wen, Jihong; Shen, Huijie; Yu, Dianlong; Wen, Xisen

    2013-11-01

    The present work describes the design of three flat superlens structures for acoustic source imaging and explores an active acoustic metamaterial (AAM) to realise such a design. The first two lenses are constructed via the coordinate transform method (CTM), and their constituent materials are anisotropic. The third lens consists of a material that has both a negative density and a negative bulk modulus. In these lenses, the quality of the images is “clear” and sharp; thus, the diffraction limit of classical lenses is overcome. Finally, a multi-control strategy is developed to achieve the desired parameters and to eliminate coupling effects in the AAM.

  3. Comparison of active millimeter-wave and acoustic imaging for weapon detection

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; Collins, H. D.; Gribble, R. Parks; McMakin, Douglas L.

    1997-02-01

    Millimeter-wave holographic imaging techniques have recently been developed for personnel surveillance applications at airports and other high-security checkpoints. Millimeter- wave imaging is useful for this application since millimeter-waves easily pass through common clothing materials yet are reflected from the human body and any items concealed by clothing. This allows a high-resolution imaging system to form an image revealing items concealed on the person imaged. A prototype imaging system developed at Pacific Northwest National Laboratory uses a scanned linear array of millimeter-wave antennas to capture wideband millimeter-wave data in approximately one second. This data is then mathematically reconstructed to form a high- resolution 3D image of the person being scanned. Millimeter- wave imaging has been demonstrated to be effective for detecting concealed weapons on personnel. Another imaging technique which could be applied to the weapon detection problem is acoustic imaging. Like millimeter-waves, ultrasonic acoustic waves can also penetrate clothing, and can be used to form relatively high-resolution images which can reveal concealed weapons on personnel. Acoustic imaging results have been obtained using wideband holographic imaging techniques nearly identical to the imaging techniques used for millimeter-wave imaging. Preliminary imaging results at 50 kHz indicate that acoustic imaging can be used to penetrate some types of common clothing materials. Hard clothing materials, such as leather on vinyl, are essentially opaque to acoustic waves at 50 kHz. In this paper, millimeter-wave and acoustic wave imaging techniques are compared for their effectiveness and suitability in weapon detection imaging systems. Experimental results from both imaging modalities are shown.

  4. Flare-Shaped Acoustic Anomalies in the Water Column Along the Ecuadorian Margin: Relationship with Active Tectonics and Gas Hydrates

    NASA Astrophysics Data System (ADS)

    Francois, Michaud; Noël, Proust Jean; Alexandre, Dano; Yves, Collot Jean; Daniella, Guiyeligou Grâce; José, Hernández Salazar María; Gueorgui, Ratzov; Carlos, Martillo; Hugo, Pouderoux; Laure, Schenini; Frederic, Lebrun Jean; Glenda, Loayza

    2016-01-01

    With hull-mounted multibeam echosounder data, we report for the first time along the active Ecuadorian margin, acoustic signatures of water column fluid emissions and seep-related structures on the seafloor. In total 17 flare-shaped acoustic anomalies were detected from the upper slope (1250 m) to the shelf break (140 m). Nearly half of the flare-shaped acoustic anomalies rise 200-500 m above the seafloor. The base of the flares is generally associated with high-reflectivity backscatter patches contrasting with the neighboring seafloor. We interpret these flares as caused by fluid escape in the water column, most likely gases. High-resolution seismic profiles show that most flares occur close to the surface expression of active faults, deformed areas, slope instabilities or diapiric structures. In two areas tectonic deformation disrupts a Bottom Simulating Reflector (BSR), suggesting that buried frozen gas hydrates are destabilized, thus supplying free gas emissions and related flares. This discovery is important as it opens the way to determine the nature and origin of the emitted fluids and their potential link with the hydrocarbon system of the forearc basins along the Ecuadorian margin.

  5. Development and Evaluation of New Coupling System for Lower Limb Prostheses with Acoustic Alarm System

    PubMed Central

    Eshraghi, Arezoo; Osman, Noor Azuan Abu; Gholizadeh, Hossein; Ahmadian, Jalil; Rahmati, Bizhan; Abas, Wan Abu Bakar Wan

    2013-01-01

    Individuals with lower limb amputation need a secure suspension system for their prosthetic devices. A new coupling system was developed that is capable of suspending the prosthesis. The system's safety is ensured through an acoustic alarm system. This article explains how the system works and provides an in vivo evaluation of the device with regard to pistoning during walking. The system was designed to be used with silicone liners and is based on the requirements of prosthetic suspension systems. Mechanical testing was performed using a universal testing machine. The pistoning during walking was measured using a motion analysis system. The new coupling device produced significantly less pistoning compared to a common suspension system (pin/lock). The safety alarm system would buzz if the suspension was going to fail. The new coupling system could securely suspend the prostheses in transtibial amputees and produced less vertical movement than the pin/lock system. PMID:23881340

  6. The utility of a long-term acoustic recording system for detecting white seabass Atractoscion nobilis spawning sounds.

    PubMed

    Aalbers, S A; Sepulveda, C A

    2012-11-01

    This study reports the use of a long-term acoustic recording system (LARS) to remotely monitor white seabass Atractoscion nobilis spawning sounds at three sites along the southern California coastline, adjacent to Camp Pendleton. On the basis of previous studies of A. nobilis sound production relative to periods of known spawning activity, LARS were set to continuously record ambient sounds for a 2 h period around sunset from April to June 2009. Acoustic analyses identified A. nobilis courtship sounds on 89, 28 and 45% of the days at the three locations, respectively. From 474 h of acoustic data, spawning-related sounds (chants) were detected on 19 occasions in 2009 with an additional 11 spawning chants recorded during a 2007 validation period. Most spawning chants occurred within 30 min of sunset during the months of May and June at a mean ±S.D. surface temperature of 18.2 ± 1.2° C. Consecutive daily spawning activity was not apparent at any sites in 2009. Atractoscion nobilis spawning chants were recorded at all three sites, suggesting that shallow rocky reefs which support kelp forests provide suitable A. nobilis spawning habitat. Results confirm the utility of passive acoustic recorders for identifying A. nobilis spawning periods and locations. PMID:23130687

  7. Acoustic, fiber optic, and silicon microelectronic microsensors research and development activities at Sandia National Laboratories

    SciTech Connect

    Wiczer, J.J.

    1993-08-01

    Sandia National Laboratories, an 8500+ person, multiprogram research and development facility operated for the US Department of Energy, has over 400 research, development and applications scientists and engineers working on sensor technologies. Sandia`s 20 person Microsensors Research and Development Department has invented, developed and fielded sensor systems based on acoustic, fiber optic, and silicon microelectronic technologies. These sensors have been used for diverse applications inducting the monitoring of cleaning chemical concentrations in industrial process effluent streams, detection of explosive gas concentrations in aging industrial equipment, real-time measurements of fluid viscosity in equipment lubricants, and monitoring of contaminant concentration levels in ultrapure process gases. Representative sensor technologies available for technology transfer will be described including bulk acoustic wave resonators, surface acoustic wave devices, fiber optic micromirror sensors, and silicon microelectronic sensors.

  8. Active Structural Acoustic Control of Interior Noise on a Raytheon 1900D

    NASA Technical Reports Server (NTRS)

    Palumbo, Dan; Cabell, Ran; Sullivan, Brenda; Cline, John

    2000-01-01

    An active structural acoustic control system has been demonstrated on a Raytheon Aircraft Company 1900D turboprop airliner. Both single frequency and multi-frequency control of the blade passage frequency and its harmonics was accomplished. The control algorithm was a variant of the popular filtered-x LMS implemented in the principal component domain. The control system consisted of 21 inertial actuators and 32 microphones. The actuators were mounted to the aircraft's ring frames. The microphones were distributed uniformly throughout the interior at head height, both seated and standing. Actuator locations were selected using a combinatorial search optimization algorithm. The control system achieved a 14 dB noise reduction of the blade passage frequency during single frequency tests. Multi-frequency control of the first 1st, 2nd and 3rd harmonics resulted in 10.2 dB, 3.3 dB and 1.6 dB noise reductions respectively. These results fall short of the predictions which were produced by the optimization algorithm (13.5 dB, 8.6 dB and 6.3 dB). The optimization was based on actuator transfer functions taken on the ground and it is postulated that cabin pressurization at flight altitude was a factor in this discrepancy.

  9. Acoustic Characterization and Impact Sensing for Ceramic Thermal Protection Systems (TPS)

    SciTech Connect

    Kuhr, S. J.; Reibel, R.; Sathish, S.; Jata, K. V.

    2006-03-06

    A study was conducted to understand acoustic wave propagation characteristics in a ceramic matrix composite (CMC) wrapped tile thermal protection system (CMC+ Foam+ RTV+ SIP+ RTV+ Al) and ceramic foam. Sound velocities were measured in three orthogonal directions on the above material. The attenuation coefficients were also determined for a uncoated ceramic foam. Commercially available standard acoustic emission transducers, piezo-wafers and polymer based PVDF (polyvinylidiene fluoride) film were employed in the experiments to acquire the acoustic data. The performance characteristics of these sensors will be discussed in light of impact detection. Variation in the wave propagation characteristics along different directions and the role of processing in causing anisotropic acoustic properties in thermal protection systems will be discussed.

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

    SciTech Connect

    Sun Hongxiang; Zhang Shuyi; Xu Baiqiang

    2011-04-01

    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.

  11. The Hebrew Vowel System: Raw and Normalized Acoustic Data.

    ERIC Educational Resources Information Center

    Most, Tova; Amir, Ofer; Tobin, Yishai

    2000-01-01

    Identified the acoustic features of the vowels produced by Hebrew speakers differing in age and sex. Ninety speakers were recorded. Vowels were presented in a nonword context that was placed in a meaningful Hebrew sentence. Results are discussed. (Author/VWL)

  12. Eliminating Nonlinear Acoustical Effects From Thermoacoustic Refrigeration Systems

    NASA Astrophysics Data System (ADS)

    Garrett, Steven L.; Smith, Robert W. M.; Poese, Matthew E.

    2006-05-01

    Nonlinear acoustical effects dissipate energy that degrades thermoacoustic refrigerator performance. The largest of these effects occur in acoustic resonators and include shock formation; turbulence and boundary layer disruption; and entry/exit (minor) losses induced by changes in resonator cross-sectional area. Effects such as these also make the creation of accurate performance models more complicated. Suppression of shock formation by intentional introduction of resonator anharmonicity has been common practice for the past two decades. Recent attempts to increase cooling power density by increasing pressure amplitudes has required reduction of turbulence and minor loss by using an new acousto-mechanical resonator topology. The hybrid resonator still stores potential energy in the compressibility of the gaseous working fluid, but stores kinetic energy in the moving (solid) mass of the motor and piston. This talk will first present nonlinear acoustical loss measurements obtained in a "conventional" double-Helmholtz resonator geometry (TRITON) that dissipated four kilowatts of acoustic power. We will then describe the performance of the new "bellows bounce" resonator configuration and "vibromechanical multiplier" used in the first successful implementation of this approach that created an ice cream freezer produced at Penn State for Ben & Jerry's.

  13. Prediction of Acoustic Loads Generated by Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Perez, Linamaria; Allgood, Daniel C.

    2011-01-01

    NASA Stennis Space Center is one of the nation's premier facilities for conducting large-scale rocket engine testing. As liquid rocket engines vary in size, so do the acoustic loads that they produce. When these acoustic loads reach very high levels they may cause damages both to humans and to actual structures surrounding the testing area. To prevent these damages, prediction tools are used to estimate the spectral content and levels of the acoustics being generated by the rocket engine plumes and model their propagation through the surrounding atmosphere. Prior to the current work, two different acoustic prediction tools were being implemented at Stennis Space Center, each having their own advantages and disadvantages depending on the application. Therefore, a new prediction tool was created, using NASA SP-8072 handbook as a guide, which would replicate the same prediction methods as the previous codes, but eliminate any of the drawbacks the individual codes had. Aside from replicating the previous modeling capability in a single framework, additional modeling functions were added thereby expanding the current modeling capability. To verify that the new code could reproduce the same predictions as the previous codes, two verification test cases were defined. These verification test cases also served as validation cases as the predicted results were compared to actual test data.

  14. Acoustic radiation from the submerged circular cylindrical shell treated with active constrained layer damping

    NASA Astrophysics Data System (ADS)

    Yuan, Li-Yun; Xiang, Yu; Lu, Jing; Jiang, Hong-Hua

    2015-12-01

    Based on the transfer matrix method of exploring the circular cylindrical shell treated with active constrained layer damping (i.e., ACLD), combined with the analytical solution of the Helmholtz equation for a point source, a multi-point multipole virtual source simulation method is for the first time proposed for solving the acoustic radiation problem of a submerged ACLD shell. This approach, wherein some virtual point sources are assumed to be evenly distributed on the axial line of the cylindrical shell, and the sound pressure could be written in the form of the sum of the wave functions series with the undetermined coefficients, is demonstrated to be accurate to achieve the radiation acoustic pressure of the pulsating and oscillating spheres respectively. Meanwhile, this approach is proved to be accurate to obtain the radiation acoustic pressure for a stiffened cylindrical shell. Then, the chosen number of the virtual distributed point sources and truncated number of the wave functions series are discussed to achieve the approximate radiation acoustic pressure of an ACLD cylindrical shell. Applying this method, different radiation acoustic pressures of a submerged ACLD cylindrical shell with different boundary conditions, different thickness values of viscoelastic and piezoelectric layer, different feedback gains for the piezoelectric layer and coverage of ACLD are discussed in detail. Results show that a thicker thickness and larger velocity gain for the piezoelectric layer and larger coverage of the ACLD layer can obtain a better damping effect for the whole structure in general. Whereas, laying a thicker viscoelastic layer is not always a better treatment to achieve a better acoustic characteristic. Project supported by the National Natural Science Foundation of China (Grant Nos. 11162001, 11502056, and 51105083), the Natural Science Foundation of Guangxi Zhuang Autonomous Region, China (Grant No. 2012GXNSFAA053207), the Doctor Foundation of Guangxi

  15. Design and utilization of a portable seismic/acoustic calibration system

    SciTech Connect

    Stump, B.W.; Pearson, D.C.

    1996-10-01

    Empirical results from the current GSETT-3 illustrate the need for source specific information for the purpose of calibrating the monitoring system. With the specified location design goal of 1,000 km{sup 2}, preliminary analysis indicates the importance of regional calibration of travel times. This calibration information can be obtained in a passive manner utilizing locations derived from local seismic array arrival times and assumes the resulting locations are accurate. Alternatively, an active approach to the problem can be undertaken, attempting to make near-source observations of seismic sources of opportunity to provide specific information on the time, location and characteristics of the source. Moderate to large mining explosions are one source type that may be amenable to such calibration. This paper describes an active ground truthing procedure for regional calibration. A prototype data acquisition system that includes the primary ground motion component for source time and location determination, and secondary, optional acoustic and video components for improved source phenomenology is discussed. The system costs approximately $25,000 and can be deployed and operated by one to two people thus providing a cost effective system for calibration and documentation of sources of interest. Practical implementation of the system is illustrated, emphasizing the minimal impact on an active mining operation.

  16. Effects of ultrasound frequency and acoustic amplitude on the size of sonochemically active bubbles - Theoretical study.

    PubMed

    Merouani, Slimane; Hamdaoui, Oualid; Rezgui, Yacine; Guemini, Miloud

    2013-05-01

    Numerical simulation of chemical reactions inside an isolated spherical bubble of oxygen has been performed for various ambient bubble radii at different frequencies and acoustic amplitudes to study the effects of these two parameters on the range of ambient radius for an active bubble in sonochemical reactions. The employed model combines the dynamic of bubble collapse with the chemical kinetics of single cavitation bubble. Results from this model were compared with some experimental results presented in the literature and good apparent trends between them were observed. The numerical calculations of this study showed that there always exists an optimal ambient bubble radius at which the production of oxidizing species at the end of the bubble collapse attained their upper limit. It was shown that the range of ambient radius for an active bubble increased with increasing acoustic amplitude and decreased with increasing ultrasound frequency. The optimal ambient radius decreased with increasing frequency. Analysis of curves showing optimal ambient radius versus acoustic amplitude for different ultrasonic frequencies indicated that for 200 and 300kHz, the optimal ambient radius increased linearly with increasing acoustic amplitude up to 3atm. However, slight minima of optimal radius were observed for the curves obtained at 500 and 1000kHz. PMID:23187064

  17. [Need for rheologically active, vasoactive and metabolically active substances in the initial treatment of acute acoustic trauma].

    PubMed

    Pilgramm, M; Schumann, K

    1986-10-01

    Two rheologically active and 8 vasoactive and metabolically active substances were compared in eight independent studies, some of which were randomised and double blind, on 400 patients who had suffered acute acoustic trauma. The control group was given saline. Spontaneous recovery was excluded as far as possible. The following substances were tested: Dextran 40, hydroxyethyl starch 40/0.5, naftidrofurylhydrogenoxalate, Vinpocetin, betahistine, pentoxifylline, flunaricine, Regeneresen AU 4 and 0.9% saline. All groups showed superior results to the control group in both long-term and short-term tests with respect to hearing gain and tinnitis improvement. The rheologically effective substances showed no statistically significant variations. None of the vasoactive or metabolically active substances used as adjunctive therapy improved the results achieved with rheologically effective substances alone. These results demonstrate that acute acoustic trauma can be most effectively treated by rheologically active substances; vasoactive and metabolically active substances are unnecessary. Hyperbaric oxygenation is advantageous as an adjunctive therapy. PMID:2432041

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  20. Effect of orientation of euphausiids and copepods on acoustic target strength: Implications for measurements from down-looking and side-looking acoustic systems

    NASA Astrophysics Data System (ADS)

    Sutor, Malinda; Cowles, Timothy J.

    2001-05-01

    Multifrequency acoustics is a potentially useful tool for zooplankton ecologists to rapidly map distributional patterns and determine taxonomic and size composition of scatterers. This is typically done with down-looking or side-looking acoustic systems. The ability to estimate taxonomic and size composition acoustically depends upon accurate models of scattering from zooplankton. In this study, distorted wave Born approximation (DWBA) models of individual zooplankton were used to illustrate that the frequency dependence of expected scattering is different for down-looking and side-looking acoustic systems due to the differences in orientation of scatters within the sampled volume. The results show that peaks and nulls occur at different frequencies for each system with maximum target strength differences of 30 dB. The models were used to predict volume scattering (SV) based on zooplankton collected from MOCNESS tows. Predicted SV was compared to SV measured by both a down-looking HTI acoustic system and a side-looking TAPS. The results showed that changes in orientation can have large effects on predicted total SV, particularly at higher frequencies, and demonstrate that choice of orientation parameters is important and different parameters should be used when comparing predicted SV with measured SV from down-looking or side-looking acoustic systems.

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

    PubMed

    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. PMID:26611016

  2. A system for acoustical and optical analysis of encapsulated microbubbles at ultrahigh hydrostatic pressures.

    PubMed

    Zhushma, Aleksandr; Lebedeva, Natalia; Sen, Pabitra; Rubinstein, Michael; Sheiko, Sergei S; Dayton, Paul A

    2013-05-01

    Acoustics are commonly used for borehole (i.e., oil well) imaging applications, under conditions where temperature and pressure reach extremes beyond that of conventional medical ultrasonics. Recently, there has been an interest in the application of encapsulated microbubbles as borehole contrast agents for acoustic assessment of fluid composition and flow. Although such microbubbles are widely studied under physiological conditions for medical imaging applications, to date there is a paucity of information on the behavior of encapsulated gas-filled microbubbles at high pressures. One major limitation is that there is a lack of experimental systems to assess both optical and acoustic data of micrometer-sized particles data at these extremes. In this paper, we present the design and application of a high-pressure cell designed for acoustical and optical studies of microbubbles at hydrostatic pressures up to 27.5 MPa (271 atm). PMID:23742587

  3. Exposure to Advertisement Calls of Reproductive Competitors Activates Vocal-Acoustic and Catecholaminergic Neurons in the Plainfin Midshipman Fish, Porichthys notatus

    PubMed Central

    Petersen, Christopher L.; Timothy, Miky; Kim, D. Spencer; Bhandiwad, Ashwin A.; Mohr, Robert A.; Sisneros, Joseph A.; Forlano, Paul M.

    2013-01-01

    While the neural circuitry and physiology of the auditory system is well studied among vertebrates, far less is known about how the auditory system interacts with other neural substrates to mediate behavioral responses to social acoustic signals. One species that has been the subject of intensive neuroethological investigation with regard to the production and perception of social acoustic signals is the plainfin midshipman fish, Porichthys notatus, in part because acoustic communication is essential to their reproductive behavior. Nesting male midshipman vocally court females by producing a long duration advertisement call. Females localize males by their advertisement call, spawn and deposit all their eggs in their mate’s nest. As multiple courting males establish nests in close proximity to one another, the perception of another male’s call may modulate individual calling behavior in competition for females. We tested the hypothesis that nesting males exposed to advertisement calls of other males would show elevated neural activity in auditory and vocal-acoustic brain centers as well as differential activation of catecholaminergic neurons compared to males exposed only to ambient noise. Experimental brains were then double labeled by immunofluorescence (-ir) for tyrosine hydroxylase (TH), an enzyme necessary for catecholamine synthesis, and cFos, an immediate-early gene product used as a marker for neural activation. Males exposed to other advertisement calls showed a significantly greater percentage of TH-ir cells colocalized with cFos-ir in the noradrenergic locus coeruleus and the dopaminergic periventricular posterior tuberculum, as well as increased numbers of cFos-ir neurons in several levels of the auditory and vocal-acoustic pathway. Increased activation of catecholaminergic neurons may serve to coordinate appropriate behavioral responses to male competitors. Additionally, these results implicate a role for specific catecholaminergic neuronal groups

  4. Exposure to advertisement calls of reproductive competitors activates vocal-acoustic and catecholaminergic neurons in the plainfin midshipman fish, Porichthys notatus.

    PubMed

    Petersen, Christopher L; Timothy, Miky; Kim, D Spencer; Bhandiwad, Ashwin A; Mohr, Robert A; Sisneros, Joseph A; Forlano, Paul M

    2013-01-01

    While the neural circuitry and physiology of the auditory system is well studied among vertebrates, far less is known about how the auditory system interacts with other neural substrates to mediate behavioral responses to social acoustic signals. One species that has been the subject of intensive neuroethological investigation with regard to the production and perception of social acoustic signals is the plainfin midshipman fish, Porichthys notatus, in part because acoustic communication is essential to their reproductive behavior. Nesting male midshipman vocally court females by producing a long duration advertisement call. Females localize males by their advertisement call, spawn and deposit all their eggs in their mate's nest. As multiple courting males establish nests in close proximity to one another, the perception of another male's call may modulate individual calling behavior in competition for females. We tested the hypothesis that nesting males exposed to advertisement calls of other males would show elevated neural activity in auditory and vocal-acoustic brain centers as well as differential activation of catecholaminergic neurons compared to males exposed only to ambient noise. Experimental brains were then double labeled by immunofluorescence (-ir) for tyrosine hydroxylase (TH), an enzyme necessary for catecholamine synthesis, and cFos, an immediate-early gene product used as a marker for neural activation. Males exposed to other advertisement calls showed a significantly greater percentage of TH-ir cells colocalized with cFos-ir in the noradrenergic locus coeruleus and the dopaminergic periventricular posterior tuberculum, as well as increased numbers of cFos-ir neurons in several levels of the auditory and vocal-acoustic pathway. Increased activation of catecholaminergic neurons may serve to coordinate appropriate behavioral responses to male competitors. Additionally, these results implicate a role for specific catecholaminergic neuronal groups in

  5. Acoustically shielded exhaust system for high thrust jet engines

    NASA Technical Reports Server (NTRS)

    Carey, John P. (Inventor); Lee, Robert (Inventor); Majjigi, Rudramuni K. (Inventor)

    1995-01-01

    A flade exhaust nozzle for a high thrust jet engine is configured to form an acoustic shield around the core engine exhaust flowstream while supplementing engine thrust during all flight conditions, particularly during takeoff. The flade airflow is converted from an annular 360.degree. flowstream to an arcuate flowstream extending around the lower half of the core engine exhaust flowstream so as to suppress exhaust noise directed at the surrounding community.

  6. Acoustic performance evaluation of an advanced UH-1 helicopter main rotor system

    NASA Technical Reports Server (NTRS)

    Hoad, D. R.; Conner, D. A.

    1981-01-01

    An experimental investigation of the high-speed impulsive noise characteristics of an advanced main rotor system for the UH-1 helicopter has been conducted. Models of both the advanced main rotor system and the UH-1 main rotor system were tested at one-quarter scale in the Langley 4- by 7-meter (V/STOL) Tunnel using the General Rotor Model System (GRMS). Tests were conducted over a range of simulated flight and descent velocities. The tunnel was operated in the open-throat configuration with acoustic treatment to improve the acoustic characteristics of the test chamber. In-plane acoustic measurements of the high-speed impulsive noise demonstrated a 7 to 8 dB reduction in noise generation is available by using the advanced rotor system on the UH-1 helicopter.

  7. Acoustic module of the Acquabona (Italy) debris flow monitoring system

    NASA Astrophysics Data System (ADS)

    Galgaro, A.; Tecca, P. R.; Genevois, R.; Deganutti, A. M.

    2005-02-01

    Monitoring of debris flows aimed to the assessment of their physical parameters is very important both for theoretical and practical purposes. Peak discharge and total volume of debris flows are crucial for designing effective countermeasures in many populated mountain areas where losses of lives and property damage could be avoided. This study quantifies the relationship between flow depth, acoustic amplitude of debris flow induced ground vibrations and front velocity in the experimental catchment of Acquabona, Eastern Dolomites, Italy. The analysis of data brought about the results described in the following. Debris flow depth and amplitude of the flow-induced ground vibrations show a good positive correlation. Estimation of both mean front velocity and peak discharge can be simply obtained monitoring the ground vibrations, through geophones installed close to the flow channel; the total volume of debris flow can be so directly estimated from the integral of the ground vibrations using a regression line. The application of acoustic technique to debris flow monitoring seems to be of the outmost relevance in risk reduction policies and in the correct management of the territory. Moreover this estimation is possible in other catchments producing debris flows of similar characteristics by means of their acoustic characterisation through quick and simple field tests (Standard Penetration Tests and seismic refraction surveys).

  8. Compact acoustic refrigerator

    DOEpatents

    Bennett, Gloria A.

    1992-01-01

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits (22), in a borehole environment. An acoustic engine (12, 14) includes first thermodynamic elements (12) for generating a standing acoustic wave in a selected medium. An acoustic refrigerator (16, 26, 28) includes second thermodynamic elements (16) located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements (16) and a relatively hot temperature at a second end of the second thermodynamic elements (16). A resonator volume (18) cooperates with the first and second thermodynamic elements (12, 16) to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements (12, 16), first heat pipes (24, 26) transfer heat from the heat load (22) to the second thermodynamic elements (16) and second heat pipes (28, 32) transfer heat from first and second thermodynamic elements (12, 16) to the borehole environment.

  9. Compact acoustic refrigerator

    SciTech Connect

    Bennett, G.A.

    1991-12-31

    This invention is comprised of a compact acoustic refrigeration system that actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment.

  10. Compact acoustic refrigerator

    DOEpatents

    Bennett, G.A.

    1992-11-24

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment. 18 figs.

  11. Fricative Consonants: AN Articulatory, Acoustic, and Systems Study.

    NASA Astrophysics Data System (ADS)

    Narayanan, Shrikanth S.

    1995-01-01

    Accurate knowledge of the articulatory and acoustic details of human speech is crucial for better understanding and modeling of our speech production mechanisms. Such knowledge is important for the development of high-quality speech synthesis, low bit rate speech coding, and improved automatic speech recognition strategies. This dissertation addresses the analysis and modeling of fricatives, a class of speech sounds characterized by turbulence generation in the vocal tract. Extensive data were collected using novel measurement techniques from four phonetically-trained native talkers of American English. Magnetic resonance imaging (MRI) provided a detailed characterization of the 3D geometry of the human vocal-tract shapes and dimensions. Dynamic electropalatography (EPG) was useful for analyzing inter - and intra-speaker variabilities while high-quality recordings provided acoustic data necessary for modeling. Results showed similarities in the general vocal -tract shapes and the corresponding area-function patterns, across subjects. The vocal-tract dimensions showed, however, significant inter-subject differences which are related to differences in the corresponding acoustic spectra. These differences are attributed to variabilities both in the individual's oral morphology and in the way a particular consonant may be articulated. Distinct tongue body shapes were associated with the different fricative places of articulation. For example, the anterior tongue body shapes were concave for the alveolar fricatives and flat/convex in the postalveolars, implying differences in their aerodynamics. Voiced lingual fricatives showed a tendency towards enlarged supraglottal volumes due to tongue-root advancement. Results of the acoustic modeling indicate that a linear source-filter model is fairly adequate for capturing the essential spectral characteristics of sustained fricatives below 10 kHz. The hybrid source models employed a combination of acoustic monopole and dipole

  12. Towards a history of Polish acoustics as part of the activity of the Institute of Basic Problems of Technology

    NASA Astrophysics Data System (ADS)

    Ranachowski, Jerzy

    As yet no detailed history of Polish acoustics exists. The easiest way to begin such an undertaking would be to start with a description of the history of specific teams led by a particular individual. The author has attempted to describe the contributions of a team of scientists working at the Institute of Basic Problems of Technology who worked closely with Professor Ignacy Malecki. The first Polish work in the field of acousticd began in the 1930's. Acoustics was taught at the clandestine Warsaw Polytechnical. A Department of Electroacoustics was established at the polytechnical. This department led to the establishment of the Vibration Research Institute of the Polish Academy of Sciences, which in 1953 became part of the academy's new Institute of Basic Problems of Technology. The Vibration Research Institute conducted acoustic research in the areas of ultrasound flaw detection, molecular acoustics, noise measurements, and speech acoustics. The institute was also engaged in theoretical research on electromechanical-acoustic analogies and coupled electroacoustic fields and theoretical and experimental studies of heterogeneous materials, especially ceramics. The institute became interested in hypersonics and quantum representations of acoustic phenomena. A quantum method was used to describe a diffraction field and the propagation of vibrations in a narrow passage. The institute went from measurements of the velocity and attenuation of ultrasound waves to a study of the active behavior of materials corresponding to acoustic emission. The institute conducted comprehensive studies of the mechanisms by which acoustic emission is generated and developed different applications for acoustic emission. Researchers investigated the acoustic emission which accompanies brittle fracture and chemical reactions. The institute cooperated with foreign researchers and engaged in educational activities related to its research.

  13. Acoustic stratigraphy and hydrothermal activity within Epi Submarine Caldera, Vanuatu, New Hebrides Arc

    USGS Publications Warehouse

    Greene, H. Gary; Exon, N.F.

    1988-01-01

    Geological and geophysical surveys of active submarine volcanoes offshore and southeast of Epi Island, Vanuatu, New Hebrides Arc, have delineated details of the structure and acoustic stratigraphy of three volcanic cones. These submarine cones, named Epia, Epib, and Epic, are aligned east-west and spaced 3.5 km apart on the rim of a submerged caldera. At least three acoustic sequences, of presumed Quaternary age, can be identified on single-channel seismic-reflection profiles. Rocks dredged from these cones include basalt, dacite, and cognate gabbroic inclusions with magmatic affinities similar to those of the Karua (an active submarine volcano off the southeastern tip of Epi) lavas. ?? 1988 Springer-Verlag New York Inc.

  14. A Galerkin method for linear PDE systems in circular geometries with structural acoustic applications

    NASA Technical Reports Server (NTRS)

    Smith, Ralph C.

    1994-01-01

    A Galerkin method for systems of PDE's in circular geometries is presented with motivating problems being drawn from structural, acoustic, and structural acoustic applications. Depending upon the application under consideration, piecewise splines or Legendre polynomials are used when approximating the system dynamics with modifications included to incorporate the analytic solution decay near the coordinate singularity. This provides an efficient method which retains its accuracy throughout the circular domain without degradation at singularity. Because the problems under consideration are linear or weakly nonlinear with constant or piecewise constant coefficients, transform methods for the problems are not investigated. While the specific method is developed for the two dimensional wave equations on a circular domain and the equation of transverse motion for a thin circular plate, examples demonstrating the extension of the techniques to a fully coupled structural acoustic system are used to illustrate the flexibility of the method when approximating the dynamics of more complex systems.

  15. An acoustic dual filter in the audio frequencies with two local resonant systems

    NASA Astrophysics Data System (ADS)

    Liu, Zhao-qun; Zhang, Hui; Zhang, Shu-yi; Fan, Li

    2014-08-01

    We report an acoustic dual filter to realize the sound regulation in the audio frequency range, in which resonant vibrations of two membrane-air and metal-elastomer systems generate two sound transmission peaks and a sound blocking below 3000 Hz. The local vibrational profiles manifest that the transmission peak at lower frequency is mainly dependent on the resonant vibration of the membrane-air system, and the coupling vibrations of two systems generate the blocking frequency and transmission peak at higher frequency. Importantly, two transmission peaks can be controlled independently. It is feasible to realize the acoustic device in sound shield and dual filters.

  16. Active structural acoustic control of a smart cylindrical shell using a virtual microphone

    NASA Astrophysics Data System (ADS)

    Loghmani, Ali; Danesh, Mohammad; Kwak, Moon K.; Keshmiri, Mehdi

    2016-04-01

    This paper investigates the active structural acoustic control of sound radiated from a smart cylindrical shell. The cylinder is equipped with piezoelectric sensors and actuators to estimate and control the sound pressure that radiates from the smart shell. This estimated pressure is referred to as a virtual microphone, and it can be used in control systems instead of actual microphones to attenuate noise due to structural vibrations. To this end, the dynamic model for the smart cylinder is derived using the extended Hamilton’s principle, the Sanders shell theory and the assumed mode method. The simplified Kirchhoff-Helmholtz integral estimates the far-field sound pressure radiating from the baffled cylindrical shell. A modified higher harmonic controller that can cope with a harmonic disturbance is designed and experimentally evaluated. The experimental tests were carried out on a baffled cylindrical aluminum shell in an anechoic chamber. The frequency response for the theoretical virtual microphone and the experimental actual microphone are in good agreement with each other, and the results show the effectiveness of the designed virtual microphone and controller in attenuating the radiated sound.

  17. Aircraft IR/acoustic detection evaluation. Volume 2: Development of a ground-based acoustic sensor system for the detection of subsonic jet-powered aircraft

    NASA Technical Reports Server (NTRS)

    Kraft, Robert E.

    1992-01-01

    The design and performance of a ground-based acoustic sensor system for the detection of subsonic jet-powered aircraft is described and specified. The acoustic detection system performance criteria will subsequently be used to determine target detection ranges for the subject contract. Although the defined system has never been built and demonstrated in the field, the design parameters were chosen on the basis of achievable technology and overall system practicality. Areas where additional information is needed to substantiate the design are identified.

  18. Comparison of acoustic and net sampling systems to determine patterns in zooplankton distribution

    NASA Astrophysics Data System (ADS)

    Sutor, Malinda; Cowles, Timothy J.; Peterson, William T.; Lamb, Jesse

    2005-10-01

    An analysis was conducted of the strengths and limitations of acoustic methods to determine biomass and taxonomic distribution patterns over the Oregon continental shelf. Measurements of volume backscatter from two different acoustic instruments were compared with each other and with predicted volume backscatter calculated from a coincident net tow. Spatially and temporally coincident data were collected from a six-frequency bioacoustic system (Tracor Acoustic Profiling System (TAPS)) and from a 1 m2 Multiple Opening Closing Net and Environmental Sensing System (MOCNESS). The combined net/acoustic tows were conducted over the Oregon continental shelf in August 2001, during both day and night. The TAPS was mounted on the upper frame of the MOCNESS and ensonified a volume of water directly in front of the net mouth. A four-frequency echosounder (Hydroacoustic Technologies Inc. (HTI)) with downward looking transducers was towed off the port side of the ship during the MOCNESS/TAPS tows. Fine-scale vertical distributions of zooplankton that were resolved acoustically were not apparent within the integrated depth strata of the individual MOCNESS net samples. The taxonomic and size composition of the zooplankton community had strong effects on volume backscatter (SV), although the magnitude of SV was not linearly related to zooplankton biomass. Predicted SV calculated from scattering models and the contents of the MOCNESS nets agreed best (sometimes within 5 dB) with measured SV from the TAPS at 420 and 700 kHz and measured SV at 420 kHz from the HTI.

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

    ERIC Educational Resources Information Center

    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…

  20. Characterization Test Report for the Mnemonics-UCS Wireless Surface Acoustic Wave Sensor System

    NASA Technical Reports Server (NTRS)

    Duncan, Joshua J.; Youngquist, Robert C.

    2013-01-01

    The scope of this testing includes the Surface Acoustic Wave Sensor System delivered to KSC: two interrogator (transceiver) systems, four temperature sensors, with wooden mounting blocks, two antennas, two power supplies, network cables, and analysis software. Also included are a number of additional temperature sensors and newly-developed hydrogen sensors

  1. Use of an Acoustic Orientation System for Indoor Travel with a Spatially Disabled Blind Man.

    ERIC Educational Resources Information Center

    Lancioni, G. E.; And Others

    1996-01-01

    An acoustic orientation system was developed that employed a portable remote control device keyed to trigger audio tones from modules placed at key locations throughout the user's home and work environments. Results found that the system helped a blind subject to move and work successfully in both settings, and the subject found it easy and…

  2. Acoustic response modeling of energetics systems in confined spaces

    NASA Astrophysics Data System (ADS)

    González, David R.; Hixon, Ray; Liou, William W.; Sanford, Matthew

    2007-04-01

    In recent times, warfighting has been taking place not in far-removed areas but within urban environments. As a consequence, the modern warfighter must adapt. Currently, an effort is underway to develop shoulder-mounted rocket launcher rounds suitable with reduced acoustic signatures for use in such environments. Of prime importance is to ensure that these acoustic levels, generated by propellant burning, reflections from enclosures, etc., are at tolerable levels without requiring excessive hearing protection. Presented below is a proof-of-concept approach aimed at developing a computational tool to aid in the design process. Unsteady, perfectly-expanded-jet simulations at two different Mach numbers and one at an elevated temperature ratio were conducted using an existing computational aeroacoustics code. From the solutions, sound pressure levels and frequency spectra were then obtained. The results were compared to sound pressure levels collected from a live-fire test of the weapon. Lastly, an outline of work that is to continue and be completed in the near future will be presented.

  3. Acoustic detection of biosonar activity of deep diving odontocetes at Josephine Seamount High Seas Marine Protected Area.

    PubMed

    Giorli, Giacomo; Au, Whitlow W L; Ou, Hui; Jarvis, Susan; Morrissey, Ronald; Moretti, David

    2015-05-01

    The temporal occurrence of deep diving cetaceans in the Josephine Seamount High Seas Marine Protected Area (JSHSMPA), south-west Portugal, was monitored using a passive acoustic recorder. The recorder was deployed on 13 May 2010 at a depth of 814 m during the North Atlantic Treaty Organization Centre for Maritime Research and Experimentation cruise "Sirena10" and recovered on 6 June 2010. The recorder was programmed to record 40 s of data every 2 min. Acoustic data analysis, for the detection and classification of echolocation clicks, was performed using automatic detector/classification systems: M3R (Marine Mammal Monitoring on Navy Ranges), a custom matlab program, and an operator-supervised custom matlab program to assess the classification performance of the detector/classification systems. M3R CS-SVM algorithm contains templates to detect beaked whales, sperm whales, blackfish (pilot and false killer whales), and Risso's dolphins. The detections of each group of odontocetes was monitored as a function of time. Blackfish and Risso's dolphins were detected every day, while beaked whales and sperm whales were detected almost every day. The hourly distribution of detections reveals that blackfish and Risso's dolphins were more active at night, while beaked whales and sperm whales were more active during daylight hours. PMID:25994682

  4. FEASIBILITY OF ACOUSTIC METHODS FOR IMPURITY GAS MONITORING IN DRY STORAGE SYSTEMS

    SciTech Connect

    Meyer, Ryan M.; Cuta, Judith M.; Jones, Anthony M.; Denslow, Kayte M.; Ramuhalli, Pradeep; Adkins, Harold E.; Hanson, Brady D.

    2015-05-01

    This paper explores the feasibility of monitoring impurities in dry storage containers (DSCs) for spent nuclear fuel using non-invasive acoustic sensing. The conceived implementation considers measurements based on changes in acoustic velocity at successive measurement intervals. Uncertainty contributions from the measurement system and temperature variability are estimated. Sources of temperature variability considered include changes in the decay heat source over time and ambient temperature variation. The results show that performance of a system which does not incorporate temperature compensation will be dependent upon geographic location and the decay heat source strength. The results also indicate that an annual measurement interval is optimal.

  5. An iterative algorithm for analysis of coupled structural-acoustic systems subject to random excitations

    NASA Astrophysics Data System (ADS)

    Zhao, Guo-Zhong; Chen, Gang; Kang, Zhan

    2012-04-01

    This paper analyzes the random response of structural-acoustic coupled systems. Most existing works on coupled structural-acoustic analysis are limited to systems under deterministic excitations due to high computational cost required by a random response analysis. To reduce the computational burden involved in the coupled random analysis, an iterative procedure based on the Pseudo excitation method has been developed. It is found that this algorithm has an overwhelming advantage in computing efficiency over traditional methods, as demonstrated by some numerical examples given in this paper.

  6. Probing the Raman-active acoustic vibrations of nanoparticles with extraordinary spectral resolution

    NASA Astrophysics Data System (ADS)

    Wheaton, Skyler; Gelfand, Ryan M.; Gordon, Reuven

    2015-01-01

    Colloidal quantum dots, viruses, DNA and all other nanoparticles have acoustic vibrations that can act as ‘fingerprints’ to identify their shape, size and mechanical properties, yet high-resolution Raman spectroscopy in this low-energy range has been lacking. Here, we demonstrate extraordinary acoustic Raman (EAR) spectroscopy to measure the Raman-active vibrations of single isolated nanoparticles in the 0.1-10 cm-1 range with ˜0.05 cm-1 resolution, to resolve peak splitting from material anisotropy and to probe the low-frequency modes of biomolecules. EAR employs a nanoaperture laser tweezer that can select particles of interest and manipulate them once identified. We therefore believe that this nanotechnology will enable expanded capabilities for the study of nanoparticles in the materials and life sciences.

  7. Submarine volcanic activity, ocean-acoustic waves and internal ocean tides

    NASA Astrophysics Data System (ADS)

    Sugioka, Hiroko; Fukao, Yoshio; Hibiya, Toshiyuki

    2005-12-01

    Submarine volcanic event often generates acoustic waves (T-waves) traveling over long distances through the low velocity channel (SOFAR) of the ocean. By a method of coherent stacking of T-waves from a submarine volcanic activity in northern Mariana, we found a significant semidiurnal variation of T-wave travel times. The amplitude of variation is an order of larger than those reported in the previous ocean sound transmission experiments. Ray-theoretical consideration for the numerically simulated ocean tides indicates that such large T-phase travel time variation is a consequence of large up-and-down movement of seawater around the axis of the SOFAR channel due to the M2 internal tide effectively converted from external tidal forcing. T-phases, a ubiquitous feature of the ocean acoustic noise field, can be used to infer internal tidal motion and the associated ocean mixing.

  8. A curved piezo-structure model: implications on active structural acoustic control.

    PubMed

    Henry, J K; Clark, R L

    1999-09-01

    Current research in Active Structural Acoustic Control (ASAC) relies heavily upon accurately capturing the application physics associated with the structure being controlled. The application of ASAC to aircraft interior noise requires a greater understanding of the dynamics of the curved panels which compose the skin of an aircraft fuselage. This paper presents a model of a simply supported curved panel with attached piezoelectric transducers. The model is validated by comparison to previous work. Further, experimental results for a simply supported curved panel test structure are presented in support of the model. The curvature is shown to affect substantially the dynamics of the panel, the integration of transducers, and the bandwidth required for structural acoustic control. PMID:10489701

  9. Experimental active structural acoustic control of simply supported plates using a weighted sum of spatial gradients.

    PubMed

    Hendricks, Daniel R; Johnson, William R; Sommerfeldt, Scott D; Blotter, Jonathan D

    2014-11-01

    A limitation currently facing active structural acoustic control (ASAC) researchers is that an ideal minimization quantity for use in the control algorithms has not been developed. A novel parameter termed the "weighted sum of spatial gradients" (WSSG) was recently developed for use in ASAC and shown to effectively attenuate acoustic radiation from a vibrating flat simply supported plate in computer simulations. This paper extends this research from computer simulations and provides experimental test results. The results presented show that WSSG is a viable control quantity and provides better results than the volume velocity approach. The paper also investigates several of the challenges presented by the use of WSSG. These include determining a method to measure WSSG experimentally, an analysis of the influence of noise on WSSG control results and complications presented when degenerate modes exist. Results are shown and discussed for several experimental configurations. PMID:25373961

  10. Acoustic waves in the atmosphere and ground generated by volcanic activity

    SciTech Connect

    Ichihara, Mie; Lyons, John; Oikawa, Jun; Takeo, Minoru

    2012-09-04

    This paper reports an interesting sequence of harmonic tremor observed in the 2011 eruption of Shinmoe-dake volcano, southern Japan. The main eruptive activity started with ashcloud forming explosive eruptions, followed by lava effusion. Harmonic tremor was transmitted into the ground and observed as seismic waves at the last stage of the effusive eruption. The tremor observed at this stage had unclear and fluctuating harmonic modes. In the atmosphere, on the other hand, many impulsive acoustic waves indicating small surface explosions were observed. When the effusion stopped and the erupted lava began explosive degassing, harmonic tremor started to be transmitted also to the atmosphere and observed as acoustic waves. Then the harmonic modes became clearer and more stable. This sequence of harmonic tremor is interpreted as a process in which volcanic degassing generates an open connection between the volcanic conduit and the atmosphere. In order to test this hypothesis, a laboratory experiment was performed and the essential features were successfully reproduced.

  11. Time dependent inflow-outflow boundary conditions for 2D acoustic systems

    NASA Technical Reports Server (NTRS)

    Watson, Willie R.; Myers, Michael K.

    1989-01-01

    An analysis of the number and form of the required inflow-outflow boundary conditions for the full two-dimensional time-dependent nonlinear acoustic system in subsonic mean flow is performed. The explicit predictor-corrector method of MacCormack (1969) is used. The methodology is tested on both uniform and sheared mean flows with plane and nonplanar sources. Results show that the acoustic system requires three physical boundary conditions on the inflow and one on the outflow boundary. The most natural choice for the inflow boundary conditions is judged to be a specification of the vorticity, the normal acoustic impedance, and a pressure gradient-density gradient relationship normal to the boundary. Specification of the acoustic pressure at the outflow boundary along with these inflow boundary conditions is found to give consistent reliable results. A set of boundary conditions developed earlier, which were intended to be nonreflecting is tested using the current method and is shown to yield unstable results for nonplanar acoustic waves.

  12. The optimization of force inputs for active structural acoustic control using a neural network

    NASA Technical Reports Server (NTRS)

    Cabell, R. H.; Lester, H. C.; Silcox, R. J.

    1992-01-01

    This paper investigates the use of a neural network to determine which force actuators, of a multi-actuator array, are best activated in order to achieve structural-acoustic control. The concept is demonstrated using a cylinder/cavity model on which the control forces, produced by piezoelectric actuators, are applied with the objective of reducing the interior noise. A two-layer neural network is employed and the back propagation solution is compared with the results calculated by a conventional, least-squares optimization analysis. The ability of the neural network to accurately and efficiently control actuator activation for interior noise reduction is demonstrated.

  13. Shelf-Scale Mapping of Fish Distribution Using Active and Passive Acoustics

    NASA Astrophysics Data System (ADS)

    Wall, Carrie C.

    Fish sound production has been associated with courtship and spawning behavior. Acoustic recordings of fish sounds can be used to identify distribution and behavior. Passive acoustic monitoring (PAM) can record large amounts of acoustic data in a specific area for days to years. These data can be collected in remote locations under potentially unsafe seas throughout a 24-hour period providing datasets unattainable using observer-based methods. However, the instruments must withstand the caustic ocean environment and be retrieved to obtain the recorded data. This can prove difficult due to the risk of PAMs being lost, stolen or damaged, especially in highly active areas. In addition, point-source sound recordings are only one aspect of fish biogeography. Passive acoustic platforms that produce low self-generated noise, have high retrieval rates, and are equipped with a suite of environmental sensors are needed to relate patterns in fish sound production to concurrently collected oceanographic conditions on large, synoptic scales. The association of sound with reproduction further invokes the need for such non-invasive, near-real time datasets that can be used to enhance current management methods limited by survey bias, inaccurate fisher reports, and extensive delays between fisheries data collection and population assessment. Red grouper (Epinephelus morio) exhibit the distinctive behavior of digging holes and producing a unique sound during courtship. These behaviors can be used to identify red grouper distribution and potential spawning habitat over large spatial scales. The goal of this research was to provide a greater understanding of the temporal and spatial distribution of red grouper sound production and holes on the central West Florida Shelf (WFS) using active sonar and passive acoustic recorders. The technology demonstrated here establishes the necessary methods to map shelf-scale fish sound production. The results of this work could aid resource

  14. Targeted Drug Delivery with Focused Ultrasound-Induced Blood-Brain Barrier Opening Using Acoustically-Activated Nanodroplets

    PubMed Central

    Chen, Cherry C.; Sheeran, Paul S.; Wu, Shih-Ying; Olumolade, Oluyemi O.; Dayton, Paul A.; Konofagou, Elisa E.

    2013-01-01

    Focused ultrasound (FUS) in the presence of systemically administered microbubbles has been shown to locally, transiently and reversibly increase the permeability of the blood-brain barrier (BBB), thus allowing targeted delivery of therapeutic agents in the brain for the treatment of central nervous system diseases. Currently, microbubbles are the only agents that have been used to facilitate the FUS-induced BBB opening. However, they are constrained within the intravascular space due to their micron-size diameters, limiting the delivery effect at or near the microvessels. In the present study, acoustically-activated nanodroplets were used as a new class of contrast agents to mediate FUS-induced BBB opening in order to study the feasibility of utilizing these nanoscale phase-shift particles for targeted drug delivery in the brain. Significant dextran delivery was achieved in the mouse hippocampus using nanodroplets at clinically relevant pressures. Passive cavitation detection was used in the attempt to establish a correlation between the amount of dextran delivered in the brain and the acoustic emission recorded during sonication. Conventional microbubbles with the same lipid shell composition and perfluorobutane core as the nanodroplets were also used to compare the efficiency of FUS-induced dextran delivery. It was found that nanodroplets had a higher BBB opening pressure threshold but a lower stable cavitation threshold than microbubbles, suggesting that contrast agent-dependent acoustic emission monitoring was needed. More homogeneous dextran delivery within the targeted hippocampus was achieved using nanodroplets without inducing inertial cavitation or compromising safety. Our results offered a new means of developing the FUS-induced BBB opening technology for potential extravascular targeted drug delivery in the brain, extending the potential drug delivery region beyond the cerebral vasculature. PMID:24096019

  15. Crack propagation analysis using acoustic emission sensors for structural health monitoring systems.

    PubMed

    Kral, Zachary; 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

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

    DOE PAGESBeta

    Kral, Zachary; 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).more » 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.« less

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

    PubMed Central

    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

  18. ACOUSTICALLY ACTIVE INJECTION CATHETER GUIDED BY ULTRASOUND: NAVIGATION TESTS IN ACUTELY ISCHEMIC PORCINE HEARTS

    PubMed Central

    Belohlavek, Marek; Katayama, Minako; Zarbatany, David; Fortuin, F. David; Fatemi, Mostafa; Nenadic, Ivan Z.; McMahon, Eileen M.

    2014-01-01

    Catheters are increasingly used therapeutically and investigatively. With complex usage comes a need for more accurate intracardiac localization than traditional guidance can provide. An injection catheter navigated by ultrasound was designed and then tested in an open-chest model of acute ischemia in eight pigs. The catheter is made “acoustically active” by a piezoelectric crystal near its tip, electronically controlled, vibrating in the acoustic frequency range, and uniquely identifiable using pulsed-wave (PW) Doppler. Another “target” crystal was sutured to the epicardium within the ischemic region. Sonomicrometry was used to measure distances between the two crystals and then compared to measurements from 2D echocardiographic images. Complete data were obtained from 7 pigs, and the correlation between sonomicrometry and ultrasound measurements was excellent (p < 0.0001, ρ = 0.9820), as was the intraclass correlation coefficient (0.96) between 2 observers. These initial experimental results suggest high accuracy of ultrasound navigation of the acoustically active catheter prototype located inside the beating left ventricle. PMID:24785441

  19. An active structural acoustic control approach for the reduction of the structure-borne road noise

    NASA Astrophysics Data System (ADS)

    Douville, Hugo; Berry, Alain; Masson, Patrice

    2002-11-01

    The reduction of the structure-borne road noise generated inside the cabin of an automobile is investigated using an Active Structural Acoustic Control (ASAC) approach. First, a laboratory test bench consisting of a wheel/suspension/lower suspension A-arm assembly has been developed in order to identify the vibroacoustic transfer paths (up to 250 Hz) for realistic road noise excitation of the wheel. Frequency Response Function (FRF) measurements between the excitation/control actuators and each suspension/chassis linkage are used to characterize the different transfer paths that transmit energy through the chassis of the car. Second, a FE/BE model (Finite/Boundary Elements) was developed to simulate the acoustic field of an automobile cab interior. This model is used to predict the acoustic field inside the cabin as a response to the measured forces applied on the suspension/chassis linkages. Finally, an experimental implementation of ASAC is presented. The control approach relies on the use of inertial actuators to modify the vibration behavior of the suspension and the automotive chassis such that its noise radiation efficiency is decreased. The implemented algorithm consists of a MIMO (Multiple-Input-Multiple-Output) feedforward configuration with a filtered-X LMS algorithm using an advanced reference signal (width FIR filters) using the Simulink/Dspace environment for control prototyping.

  20. Acoustically-Active Microbubbles Conjugated to Liposomes: Characterization of a Proposed Drug Delivery Vehicle

    PubMed Central

    Kheirolomoom, Azadeh; Dayton, Paul A.; Lum, Aaron F. H.; Little, Erika; Paoli, Eric E.; Zheng, Hairong; Ferrara, Katherine W.

    2009-01-01

    A new acoustically-active delivery vehicle was developed by conjugating liposomes and microbubbles, using the high affinity interaction between avidin and biotin. Binding between microbubbles and liposomes each containing 5% DSPE-PEG2kBiotin was highly dependent on avidin concentration and observed above an avidin concentration of 10 nM. With an optimized avidin and liposome concentration, we measured and calculated as high as 1000 to 10,000 liposomes with average diameters of 200 and 100 nm, respectively, attached to each microbubble. Replacing avidin with neutravidin resulted in 3-fold higher binding, approaching the calculated saturation level. High-speed photography of this new drug delivery vehicle demonstrated that the liposome-bearing microbubbles oscillate in response to an acoustic pulse similar to microbubble contrast agents. Additionally, microbubbles carrying liposomes could be spatially concentrated on a monolayer of PC-3 cells at the focal point of ultrasound beam. As a result of cell-vehicle contact, the liposomes fused with the cells and internalization of NBD-cholesterol occurred shortly after incubation at 37°C, with internalization of NBD-cholesterol substantially enhanced in the acoustic focus. PMID:17300849

  1. Acoustic field interaction with a boiling system under terrestrial gravity and microgravity.

    PubMed

    Sitter, J S; Snyder, T J; Chung, J N; Marston, P L

    1998-11-01

    Pool boiling experiments from a platinum wire heater in FC-72 liquid were conducted under terrestrial and microgravity conditions, both with and without the presence of a high-intensity acoustic standing wave within the fluid. The purpose of this research was to study the interaction between an acoustic field and a pool boiling system in normal gravity and microgravity. The absence of buoyancy in microgravity complicates the process of boiling. The acoustic force on a vapor bubble generated from a heated wire in a standing wave was shown to be able to play the role of buoyancy in microgravity. The microgravity environment was achieved with 0.6 and 2.1-s drop towers. The sound was transmitted through the fluid medium by means of a half wavelength sonic transducer driven at 10.18 kHz. At high enough acoustic pressure amplitudes cavitation and streaming began playing an important role in vapor bubble dynamics and heat transfer. Several different fixed heat fluxes were chosen for the microgravity experiment and the effects of acoustics on the surface temperature of the heater were recorded and the vapor bubble movement was filmed. Video images of the pool boiling processes and heat transfer data are presented. PMID:9821335

  2. The Doppler Effect based acoustic source separation for a wayside train bearing monitoring system

    NASA Astrophysics Data System (ADS)

    Zhang, Haibin; Zhang, Shangbin; He, Qingbo; Kong, Fanrang

    2016-01-01

    Wayside acoustic condition monitoring and fault diagnosis for train bearings depend on acquired acoustic signals, which consist of mixed signals from different train bearings with obvious Doppler distortion as well as background noises. This study proposes a novel scheme to overcome the difficulties, especially the multi-source problem in wayside acoustic diagnosis system. In the method, a time-frequency data fusion (TFDF) strategy is applied to weaken the Heisenberg's uncertainty limit for a signal's time-frequency distribution (TFD) of high resolution. Due to the Doppler Effect, the signals from different bearings have different time centers even with the same frequency. A Doppler feature matching search (DFMS) algorithm is then put forward to locate the time centers of different bearings in the TFD spectrogram. With the determined time centers, time-frequency filters (TFF) are designed with thresholds to separate the acoustic signals in the time-frequency domain. Then the inverse STFT (ISTFT) is taken and the signals are recovered and filtered aiming at each sound source. Subsequently, a dynamical resampling method is utilized to remove the Doppler Effect. Finally, accurate diagnosis for train bearing faults can be achieved by applying conventional spectrum analysis techniques to the resampled data. The performance of the proposed method is verified by both simulated and experimental cases. It shows that it is effective to detect and diagnose multiple defective bearings even though they produce multi-source acoustic signals.

  3. Acoustic and optical multi-sensor threat detection system for border patrol against aerial threats

    NASA Astrophysics Data System (ADS)

    Alsawadi, Motasem S.; Ismail, Ahmad; Al-Azem, Badeea F.; El-Desouki, Munir M.; Alghamdi, Sultan; Alghamdi, Mansour

    2012-10-01

    Saudi Arabia has borders covering over 4,300 km that are shared with seven countries. Such large borders pose many challenges for security and patrol. Thermal imagers are considered the most reliable means of threat detection, however, they are quite costly, which can prevent using them over large areas. This work discusses a multi-sensor acoustic and optical implementation for threat detection as an effort to reduce system cost. The acoustic sensor provides position and direction recognition by using a four microphone setup. The data analysis of field tests will be discussed in this work.

  4. Acoustic natural frequency analysis of tree-structure pipeline systems by personal computer

    NASA Astrophysics Data System (ADS)

    Györi, I.; Joó, Gy.

    1986-02-01

    The paper gives the extension of the Schmidt-Kuhlmann method for reciprocating compressor pipeline systems having a tree-structure, consisting of receivers and pipes with an optional number of branchings. It gives a generalized algorithm which makes it possible to mechanize program constructing for the purpose of determining acoustic natural frequencies of complex structures, and it illustrates the use of personal computers—besides the actual numerical calculations—for automatic program-writing as well. The program developed is very useful in design practice for determining the effects caused by modification of the geometric dimensions, and it permits one to shift and avoid harmful acoustic resonances in preliminary planning.

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

    SciTech Connect

    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.

  6. Opti-acoustic stereo imaging: on system calibration and 3-D target reconstruction.

    PubMed

    Negahdaripour, Shahriar; Sekkati, Hicham; Pirsiavash, Hamed

    2009-06-01

    Utilization of an acoustic camera for range measurements is a key advantage for 3-D shape recovery of underwater targets by opti-acoustic stereo imaging, where the associated epipolar geometry of optical and acoustic image correspondences can be described in terms of conic sections. In this paper, we propose methods for system calibration and 3-D scene reconstruction by maximum likelihood estimation from noisy image measurements. The recursive 3-D reconstruction method utilized as initial condition a closed-form solution that integrates the advantages of two other closed-form solutions, referred to as the range and azimuth solutions. Synthetic data tests are given to provide insight into the merits of the new target imaging and 3-D reconstruction paradigm, while experiments with real data confirm the findings based on computer simulations, and demonstrate the merits of this novel 3-D reconstruction paradigm. PMID:19380272

  7. Micro-battery Development for Juvenile Salmon Acoustic Telemetry System Applications

    SciTech Connect

    Chen, Honghao; Cartmell, Samuel S.; Wang, Qiang; Lozano, Terence J.; Deng, Zhiqun; Li, Huidong; Chen, Xilin; Yuan, Yong; Gross, Mark E.; Carlson, Thomas J.; Xiao, Jie

    2014-01-21

    The Juvenile Salmon Acoustic Telemetry System (JSATS) project supported by the U.S. Army Corps of Engineers, Portland District, has yielded the smallest acoustic fish tag transmitter commercially available to date. In order to study even smaller fish populations and make the transmitter injectable by needles, the JSATS acoustic micro transmitter needs to be further downsized. This study focuses on the optimization of microbattery design based on Li/CFx chemistry. Through appropriate modifications, a steady high-rate pulse current with desirable life time has been achieved while the weight and volume of the battery is largely reduced. The impedance variation in as-designed microbatteries is systematically compared with that of currently used watch batteries in JSATS with an attempt to understand the intrinsic factors that control the performances of microbatteries under the real testing environments.

  8. Dynamical energy analysis for built-up acoustic systems at high frequencies.

    PubMed

    Chappell, D J; Giani, S; Tanner, G

    2011-09-01

    Standard methods for describing the intensity distribution of mechanical and acoustic wave fields in the high frequency asymptotic limit are often based on flow transport equations. Common techniques are statistical energy analysis, employed mostly in the context of vibro-acoustics, and ray tracing, a popular tool in architectural acoustics. Dynamical energy analysis makes it possible to interpolate between standard statistical energy analysis and full ray tracing, containing both of these methods as limiting cases. In this work a version of dynamical energy analysis based on a Chebyshev basis expansion of the Perron-Frobenius operator governing the ray dynamics is introduced. It is shown that the technique can efficiently deal with multi-component systems overcoming typical geometrical limitations present in statistical energy analysis. Results are compared with state-of-the-art hp-adaptive discontinuous Galerkin finite element simulations. PMID:21895083

  9. Adaptations of Acoustic Technology for Detection of Hidden Insect Infestations in Trees and Their Root Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insects that attack the trunks and roots of trees are difficult to detect and control because the tree structures hide and protect them. The vibrations caused by insects moving and feeding within the root systems can travel over long distances; consequently, acoustic technology is a likely candidat...

  10. Designing an Acoustic Suspension Speaker System in the General Physics Laboratory: A Divergent experiment

    ERIC Educational Resources Information Center

    Horton, Philip B.

    1969-01-01

    Describes a student laboratory project involving the design of an "acoustic suspension speaker system. The characteristics of the loudspeaker used are measured as an extension of the inertia-balance experiment. The experiment may be extended to a study of Stelmholtz resonators, coupled oscillators, electromagnetic forces, thermodynamics and…

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

    PubMed Central

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

    2013-01-01

    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. PMID:23698266

  12. Active optical zoom system

    DOEpatents

    Wick, David V.

    2005-12-20

    An active optical zoom system changes the magnification (or effective focal length) of an optical imaging system by utilizing two or more active optics in a conventional optical system. The system can create relatively large changes in system magnification with very small changes in the focal lengths of individual active elements by leveraging the optical power of the conventional optical elements (e.g., passive lenses and mirrors) surrounding the active optics. The active optics serve primarily as variable focal-length lenses or mirrors, although adding other aberrations enables increased utility. The active optics can either be LC SLMs, used in a transmissive optical zoom system, or DMs, used in a reflective optical zoom system. By appropriately designing the optical system, the variable focal-length lenses or mirrors can provide the flexibility necessary to change the overall system focal length (i.e., effective focal length), and therefore magnification, that is normally accomplished with mechanical motion in conventional zoom lenses. The active optics can provide additional flexibility by allowing magnification to occur anywhere within the FOV of the system, not just on-axis as in a conventional system.

  13. Music-induced emotions can be predicted from a combination of brain activity and acoustic features.

    PubMed

    Daly, Ian; Williams, Duncan; Hallowell, James; Hwang, Faustina; Kirke, Alexis; Malik, Asad; Weaver, James; Miranda, Eduardo; Nasuto, Slawomir J

    2015-12-01

    It is widely acknowledged that music can communicate and induce a wide range of emotions in the listener. However, music is a highly-complex audio signal composed of a wide range of complex time- and frequency-varying components. Additionally, music-induced emotions are known to differ greatly between listeners. Therefore, it is not immediately clear what emotions will be induced in a given individual by a piece of music. We attempt to predict the music-induced emotional response in a listener by measuring the activity in the listeners electroencephalogram (EEG). We combine these measures with acoustic descriptors of the music, an approach that allows us to consider music as a complex set of time-varying acoustic features, independently of any specific music theory. Regression models are found which allow us to predict the music-induced emotions of our participants with a correlation between the actual and predicted responses of up to r=0.234,p<0.001. This regression fit suggests that over 20% of the variance of the participant's music induced emotions can be predicted by their neural activity and the properties of the music. Given the large amount of noise, non-stationarity, and non-linearity in both EEG and music, this is an encouraging result. Additionally, the combination of measures of brain activity and acoustic features describing the music played to our participants allows us to predict music-induced emotions with significantly higher accuracies than either feature type alone (p<0.01). PMID:26544602

  14. Interaction of reed and acoustic resonator in clarinetlike systems.

    PubMed

    Silva, Fabrice; Kergomard, Jean; Vergez, Christophe; Gilbert, Joël

    2008-11-01

    Sound emergence in clarinetlike instruments is investigated in terms of instability of the static regime. Various models of reed-bore coupling are considered, from the pioneering work of Wilson and Beavers ["Operating modes of the clarinet," J. Acoust. Soc. Am. 56, 653-658 (1974)] to more recent modeling including viscothermal bore losses and vena contracta at the reed inlet. The pressure threshold above which these models may oscillate as well as the frequency of oscillation at threshold are calculated. In addition to Wilson and Beavers' previous conclusions concerning the role of the reed damping in the selection of the register the instrument will play on, the influence of the reed motion induced flow is also emphasized, particularly its effect on playing frequencies, contributing to reduce discrepancies between Wilson and Beavers' experimental results and theory, despite discrepancies still remain concerning the pressure threshold. Finally, analytical approximations of the oscillating solution based on Fourier series expansion are obtained in the vicinity of the threshold of oscillation. This allows to emphasize the conditions which determine the nature of the bifurcation (direct or inverse) through which the note may emerge, with therefore important consequences on the musical playing performances. PMID:19045811

  15. An investigation of thermally driven acoustical oscillations in helium systems

    SciTech Connect

    Fuerst, J.D.

    1990-08-01

    The phenomenon of thermal-acoustic oscillation is seen to arise spontaneously in gas columns subjected to steep temperature gradients, particularly in tubes connecting liquid helium reservoirs with the ambient environment. This if often the arrangement for installed cryogenic instrumentation and is accompanied by undesirably large heat transfer rates to the cold region. Experimental data are collected and matched to theoretical predictions of oscillatory behavior; these results are in good agreement with the analytical model and with previously collected data. The present experiment places the open ends of oscillating tubes of the various lengths and cross sections in communication with flowing helium in the subcooled, 2-phase, or superheated state while the other ends are maintained at some controlled, elevated temperature. Assorted cold end conditions are achieved through adjustments to the Fermilab Tevatron satellite test refrigerator to which the test cryostat is connected. The warm, closed ends of the tubes are maintained by isothermal baths of liquid nitrogen, ice water, and boiling water. The method is contrasted to previous arrangements whereby tubes are run from room temperature into or adjacent to a stagnant pool of liquid helium. Additionally, the effect of pulsations in the flowing helium stream is explored through operation of the refrigerator's wet and dry expanders during data collection. These data confirm the theory to which try were compared and support its use in the design of cryogenic sensing lines for avoidance of thermoacoustic oscillation.

  16. Coded acoustic wave sensors and system using time diversity

    NASA Technical Reports Server (NTRS)

    Solie, Leland P. (Inventor); Hines, Jacqueline H. (Inventor)

    2012-01-01

    An apparatus and method for distinguishing between sensors that are to be wirelessly detected is provided. An interrogator device uses different, distinct time delays in the sensing signals when interrogating the sensors. The sensors are provided with different distinct pedestal delays. Sensors that have the same pedestal delay as the delay selected by the interrogator are detected by the interrogator whereas other sensors with different pedestal delays are not sensed. Multiple sensors with a given pedestal delay are provided with different codes so as to be distinguished from one another by the interrogator. The interrogator uses a signal that is transmitted to the sensor and returned by the sensor for combination and integration with the reference signal that has been processed by a function. The sensor may be a surface acoustic wave device having a differential impulse response with a power spectral density consisting of lobes. The power spectral density of the differential response is used to determine the value of the sensed parameter or parameters.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26091392

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

    PubMed

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

    2015-01-01

    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. PMID:26091392

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

    NASA Technical Reports Server (NTRS)

    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.

  20. Acoustic Doppler Current Profiler Data Processing System manual [ADCP

    USGS Publications Warehouse

    Cote, Jessica M.; Hotchkiss, Frances S.; Martini, Marinna; Denham, Charles R.; revisions by Ramsey, Andree L.; Ruane, Stephen

    2000-01-01

    This open-file report describes the data processing software currently in use by the U.S. Geological Survey (USGS), Woods Hole Coastal and Marine Science Center (WHCMSC), to process time series of acoustic Doppler current data obtained by Teledyne RD Instruments Workhorse model ADCPs. The Sediment Transport Instrumentation Group (STG) at the WHCMSC has a long-standing commitment to providing scientists high quality oceanographic data published in a timely manner. To meet this commitment, STG has created this software to aid personnel in processing and reviewing data as well as evaluating hardware for signs of instrument malfunction. The output data format for the data is network Common Data Form (netCDF), which meets USGS publication standards. Typically, ADCP data are recorded in beam coordinates. This conforms to the USGS philosophy to post-process rather than internally process data. By preserving the original data quality indicators as well as the initial data set, data can be evaluated and reprocessed for different types of analyses. Beam coordinate data are desirable for internal and surface wave experiments, for example. All the code in this software package is intended to run using the MATLAB program available from The Mathworks, Inc. As such, it is platform independent and can be adapted by the USGS and others for specialized experiments with non-standard requirements. The software is continuously being updated and revised as improvements are required. The most recent revision may be downloaded from: http://woodshole.er.usgs.gov/operations/stg/Pubs/ADCPtools/adcp_index.htm The USGS makes this software available at the user?s discretion and responsibility.

  1. Detachable Acoustofluidic System for Particle Separation via a Traveling Surface Acoustic Wave.

    PubMed

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

    2016-05-17

    Components in biomedical analysis tools that have direct contact with biological samples, especially biohazardous materials, are ideally discarded after use to prevent cross-contamination. However, a conventional acoustofluidic device is typically a monolithic integration that permanently bonds acoustic transducers with microfluidic channels, increasing processing costs in single-use platforms. In this study, we demonstrate a detachable acoustofluidic system comprised of a disposable channel device and a reusable acoustic transducer for noncontact continuous particle separation via a traveling surface acoustic wave (TSAW). The channel device can be placed onto the SAW transducer with a high alignment tolerance to simplify operation, is made entirely of polydimethylsiloxane (PDMS), and does not require any additional coupling agent. A microstructured pillar is used to couple acoustic waves into the fluid channel for noncontact particle manipulation. We demonstrate the separation of 10 and 15 μm particles at high separation efficiency above 98% in a 49.5 MHz TSAW using the developed detachable acoustofluidic system. Its disposability and ease of assembly should enable broad use of noncontact, disposable particle manipulation techniques in practical biomedical applications related to sample preparation. PMID:27086552

  2. Experimental and theoretical identification of a four- acoustic-inputs/two-vibration-outputs hearing system

    NASA Astrophysics Data System (ADS)

    Balaji, P. A.

    1999-07-01

    A cricket's ear is a directional acoustic sensor. It has a remarkable level of sensitivity to the direction of sound propagation in a narrow frequency bandwidth of 4-5 KHz. Because of its complexity, the directional sensitivity has long intrigued researchers. The cricket's ear is a four-acoustic-inputs/two-vibration-outputs system. In this dissertation, this system is examined in depth, both experimentally and theoretically, with a primary goal to understand the mechanics involved in directional hearing. Experimental identification of the system is done by using random signal processing techniques. Theoretical identification of the system is accomplished by analyzing sound transmission through complex trachea of the ear. Finally, a description of how the cricket achieves directional hearing sensitivity is proposed. The fundamental principle involved in directional heating of the cricket has been utilized to design a device to obtain a directional signal from non- directional inputs.

  3. Estimating suspended sediment using acoustics in a fine-grained riverine system, Kickapoo Creek at Bloomington, Illinois

    USGS Publications Warehouse

    Manaster, Amanda D.; Domanski, Marian M.; Straub, Timothy D.; Boldt, Justin A.

    2016-01-01

    Acoustic technologies have the potential to be used as a surrogate for measuring suspended-sediment concentration (SSC). This potential was examined in a fine-grained (97-100 percent fines) riverine system in central Illinois by way of installation of an acoustic instrument. Acoustic data were collected continuously over the span of 5.5 years. Acoustic parameters were regressed against SSC data to determine the accuracy of using acoustic technology as a surrogate for measuring SSC in a fine-grained riverine system. The resulting regressions for SSC and sediment acoustic parameters had coefficients of determination ranging from 0.75 to 0.97 for various events and configurations. The overall Nash-Sutcliffe model-fit efficiency was 0.95 for the 132 observed and predicted SSC values determined using the sediment acoustic parameter regressions. The study of using acoustic technologies as a surrogate for measuring SSC in fine-grained riverine systems is ongoing. The results at this site are promising in the realm of surrogate technology.

  4. A hardware model of the auditory periphery to transduce acoustic signals into neural activity

    PubMed Central

    Tateno, Takashi; Nishikawa, Jun; Tsuchioka, Nobuyoshi; Shintaku, Hirofumi; Kawano, Satoyuki

    2013-01-01

    To improve the performance of cochlear implants, we have integrated a microdevice into a model of the auditory periphery with the goal of creating a microprocessor. We constructed an artificial peripheral auditory system using a hybrid model in which polyvinylidene difluoride was used as a piezoelectric sensor to convert mechanical stimuli into electric signals. To produce frequency selectivity, the slit on a stainless steel base plate was designed such that the local resonance frequency of the membrane over the slit reflected the transfer function. In the acoustic sensor, electric signals were generated based on the piezoelectric effect from local stress in the membrane. The electrodes on the resonating plate produced relatively large electric output signals. The signals were fed into a computer model that mimicked some functions of inner hair cells, inner hair cell–auditory nerve synapses, and auditory nerve fibers. In general, the responses of the model to pure-tone burst and complex stimuli accurately represented the discharge rates of high-spontaneous-rate auditory nerve fibers across a range of frequencies greater than 1 kHz and middle to high sound pressure levels. Thus, the model provides a tool to understand information processing in the peripheral auditory system and a basic design for connecting artificial acoustic sensors to the peripheral auditory nervous system. Finally, we discuss the need for stimulus control with an appropriate model of the auditory periphery based on auditory brainstem responses that were electrically evoked by different temporal pulse patterns with the same pulse number. PMID:24324432

  5. Operational experience with a long-range, multi-channel acoustic telemetry system

    SciTech Connect

    High, G.; Carman, R.J.

    1985-01-01

    This paper describes the design, installation, and long-term operation of a modular subsea acoustic data acquisition system in the Duncan/Argyll field, North Sea. This equipment is presently providing on-demand pressure data from eight satellite locations at ranges in excess of seven kilometres. The discussion covers the use of in-field noise measurements for optimizing system performance in a high noise environment. Two main sections cover firstly platform installation and seabed installation of the subsea transceiver. Secondly at the remote wellhead locations, the acoustic transponders are described. Cost factors, as compared with hardwired or diver-monitored data acquisition systems are discussed. Modular design permits convenient addition of other data channels and/or extra remote subsea units. The surface equipment installed at the platform is software controlled so that display and data logging can be configured according to operator needs. Variations of the same basis system are discussed, as currently in use for subsea pipeline valve actuation, and submersible flowline tow-out instrumentation. Results of several years of operational experience in various offshore applications give confidence that, when properly considered in system design, an acoustic telemetry system can function reliably at useful ranges in the offshore environment.

  6. Active Control of Fan Noise: Feasibility Study. Volume 5; Numerical Computation of Acoustic Mode Reflection Coefficients for an Unflanged Cylindrical Duct

    NASA Technical Reports Server (NTRS)

    Kraft, R. E.

    1996-01-01

    A computational method to predict modal reflection coefficients in cylindrical ducts has been developed based on the work of Homicz, Lordi, and Rehm, which uses the Wiener-Hopf method to account for the boundary conditions at the termination of a thin cylindrical pipe. The purpose of this study is to develop a computational routine to predict the reflection coefficients of higher order acoustic modes impinging on the unflanged termination of a cylindrical duct. This effort was conducted wider Task Order 5 of the NASA Lewis LET Program, Active Noise Control of aircraft Engines: Feasibility Study, and will be used as part of the development of an integrated source noise, acoustic propagation, ANC actuator coupling, and control system algorithm simulation. The reflection coefficient prediction will be incorporated into an existing cylindrical duct modal analysis to account for the reflection of modes from the duct termination. This will provide a more accurate, rapid computation design tool for evaluating the effect of reflected waves on active noise control systems mounted in the duct, as well as providing a tool for the design of acoustic treatment in inlet ducts. As an active noise control system design tool, the method can be used preliminary to more accurate but more numerically intensive acoustic propagation models such as finite element methods. The resulting computer program has been shown to give reasonable results, some examples of which are presented. Reliable data to use for comparison is scarce, so complete checkout is difficult, and further checkout is needed over a wider range of system parameters. In future efforts the method will be adapted as a subroutine to the GEAE segmented cylindrical duct modal analysis program.

  7. Acoustic containerless experiment system: A non-contact surface tension measurement

    NASA Technical Reports Server (NTRS)

    Elleman, D. D.; Wang, T. G.; Barmatz, M.

    1988-01-01

    The Acoustic Containerless Experiment System (ACES) was flown on STS 41-B in February 1984 and was scheduled to be reflown in 1986. The primary experiment that was to be conducted with the ACES module was the containerless melting and processing of a fluoride glass sample. A second experiment that was to be conducted was the verification of a non-contact surface tension measurement technique using the molten glass sample. The ACES module consisted of a three-axis acoustic positioning module that was inside an electric furnace capable of heating the system above the melting temperature of the sample. The acoustic module is able to hold the sample with acoustic forces in the center of the chamber and, in addition, has the capability of applying a modulating force on the sample along one axis of the chamber so that the molten sample or liquid drop could be driven into one of its normal oscillation modes. The acoustic module could also be adjusted so that it could place a torque on the molten drop and cause the drop to rotate. In the ACES, a modulating frequency was applied to the drop and swept through a range of frequencies that would include the n = 2 mode. A maximum amplitude of the drop oscillation would indicate when resonance was reached and from that data the surface tension could be calculated. For large viscosity samples, a second technique for measuring surface tension was developed. The results of the ACES experiment and some of the problems encountered during the actual flight of the experiment will be discussed.

  8. Accuracy of acoustic velocity metering systems for measurement of low velocity in open channels

    USGS Publications Warehouse

    Laenen, Antonius; Curtis, R.E., Jr.

    1989-01-01

    Acoustic velocity meter (AVM) accuracy depends on equipment limitations, the accuracy of acoustic-path length and angle determination, and the stability of the mean velocity to acoustic-path velocity relation. Equipment limitations depend on path length and angle, transducer frequency, timing oscillator frequency, and signal-detection scheme. Typically, the velocity error from this source is about +or-1 to +or-10 mms/sec. Error in acoustic-path angle or length will result in a proportional measurement bias. Typically, an angle error of one degree will result in a velocity error of 2%, and a path-length error of one meter in 100 meter will result in an error of 1%. Ray bending (signal refraction) depends on path length and density gradients present in the stream. Any deviation from a straight acoustic path between transducer will change the unique relation between path velocity and mean velocity. These deviations will then introduce error in the mean velocity computation. Typically, for a 200-meter path length, the resultant error is less than one percent, but for a 1,000 meter path length, the error can be greater than 10%. Recent laboratory and field tests have substantiated assumptions of equipment limitations. Tow-tank tests of an AVM system with a 4.69-meter path length yielded an average standard deviation error of 9.3 mms/sec, and the field tests of an AVM system with a 20.5-meter path length yielded an average standard deviation error of a 4 mms/sec. (USGS)

  9. The development of a biomimetic acoustic direction finding system for use on multiple platforms

    NASA Astrophysics Data System (ADS)

    Deligeorges, Socrates; Anderson, David; Browning, Cassandra A.; Cohen, Howard; Freedman, David; Gore, Tyler; Karl, Christian; Kelsall, Sarah; Mountain, David; Nourzad, Marianne; Pu, Yirong; Sandifer, Matt; Xue, Shuwan; Ziph-Schatzberg, Leah; Hubbard, Allyn

    2008-04-01

    This paper describes the flow of scientific and technological achievements beginning with a stationary "small, smart, biomimetic acoustic processor" designed for DARPA that led to a program aimed at acoustic characterization and direction finding for multiple, mobile platforms. ARL support and collaboration has allowed us to adapt the core technology to multiple platforms including a Packbot robotic platform, a soldier worn platform, as well as a vehicle platform. Each of these has varying size and power requirements, but miniaturization is an important component of the program for creating practical systems which we address further in companion papers. We have configured the system to detect and localize gunfire and tested system performance with live fire from numerous weapons such as the AK47, the Dragunov, and the AR15. The ARL-sponsored work has led to connections with Natick Labs and the Future Force Warrior program, and in addition, the work has many and obvious applications to homeland defense, police, and civilian needs.

  10. DARPA counter-sniper program: Phase 1 Acoustic Systems Demonstration results

    NASA Astrophysics Data System (ADS)

    Carapezza, Edward M.; Law, David B.; Csanadi, Christina J.

    1997-02-01

    During October 1995 through May 1996, the Defense Advanced Research Projects Agency sponsored the development of prototype systems that exploit acoustic muzzle blast and ballistic shock wave signatures to accurately predict the location of gunfire events and associated shooter locations using either single or multiple volumetric arrays. The output of these acoustic systems is an estimate of the shooter location and a classification estimate of the caliber of the shooter's weapon. A portable display and control unit provides both graphical and alphanumeric shooter location related information integrated on a two- dimensional digital map of the defended area. The final Phase I Acoustic Systems Demonstration field tests were completed in May. These these tests were held at USMC Base Camp Pendleton Military Operations Urban Training (MOUT) facility. These tests were structured to provide challenging gunfire related scenarios with significant reverberation and multi-path conditions. Special shot geometries and false alarms were included in these tests to probe potential system vulnerabilities and to determine the performance and robustness of the systems. Five prototypes developed by U.S. companies and one Israeli developed prototype were tested. This analysis quantifies the spatial resolution estimation capability (azimuth, elevation and range) of these prototypes and describes their ability to accurately classify the type of bullet fired in a challenging urban- like setting.

  11. Structural Acoustic Characteristics of Aircraft and Active Control of Interior Noise

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1998-01-01

    The reduction of aircraft cabin sound levels to acceptable values still remains a topic of much research. The use of conventional passive approaches has been extensively studied and implemented. However performance limits of these techniques have been reached. In this project, new techniques for understanding the structural acoustic behavior of aircraft fuselages and the use of this knowledge in developing advanced new control approaches are investigated. A central feature of the project is the Aircraft Fuselage Test Facility at Va Tech which is based around a full scale Cessna Citation III fuselage. The work is divided into two main parts; the first part investigates the use of an inverse technique for identifying dominant fuselage vibrations. The second part studies the development and implementation of active and active-passive techniques for controlling aircraft interior noise.

  12. Investigation of an acoustical holography system for real-time imaging

    NASA Astrophysics Data System (ADS)

    Fecht, Barbara A.; Andre, Michael P.; Garlick, George F.; Shelby, Ronald L.; Shelby, Jerod O.; Lehman, Constance D.

    1998-07-01

    A new prototype imaging system based on ultrasound transmission through the object of interest -- acoustical holography -- was developed which incorporates significant improvements in acoustical and optical design. This system is being evaluated for potential clinical application in the musculoskeletal system, interventional radiology, pediatrics, monitoring of tumor ablation, vascular imaging and breast imaging. System limiting resolution was estimated using a line-pair target with decreasing line thickness and equal separation. For a swept frequency beam from 2.6 - 3.0 MHz, the minimum resolution was 0.5 lp/mm. Apatite crystals were suspended in castor oil to approximate breast microcalcifications. Crystals from 0.425 - 1.18 mm in diameter were well resolved in the acoustic zoom mode. Needle visibility was examined with both a 14-gauge biopsy needle and a 0.6 mm needle. The needle tip was clearly visible throughout the dynamic imaging sequence as it was slowly inserted into a RMI tissue-equivalent breast biopsy phantom. A selection of human images was acquired in several volunteers: a 25 year-old female volunteer with normal breast tissue, a lateral view of the elbow joint showing muscle fascia and tendon insertions, and the superficial vessels in the forearm. Real-time video images of these studies will be presented. In all of these studies, conventional sonography was used for comparison. These preliminary investigations with the new prototype acoustical holography system showed favorable results in comparison to state-of-the-art pulse-echo ultrasound and demonstrate it to be suitable for further clinical study. The new patient interfaces will facilitate orthopedic soft tissue evaluation, study of superficial vascular structures and potentially breast imaging.

  13. Acoustic measurements of the 1999 basaltic eruption of Shishaldin volcano, Alaska 1. Origin of Strombolian activity

    USGS Publications Warehouse

    Vergniolle, S.; Boichu, M.; Caplan-Auerbach, J.

    2004-01-01

    The 1999 basaltic eruption of Shishaldin volcano (Alaska, USA) displayed both classical Strombolian activity and an explosive Subplinian plume. Strombolian activity at Shishaldin occurred in two major phases following the Subplinian activity. In this paper, we use acoustic measurements to interpret the Strombolian activity. Acoustic measurements of the two Strombolian phases show a series of explosions that are modeled by the vibration of a large overpressurised cylindrical bubble at the top of the magma column. Results show that the bubble does not burst at its maximum radius, as expected if the liquid film is stretched beyond its elasticity. But bursting occurs after one cycle of vibration, as a consequence of an instability of the air-magma interface close to the bubble minimum radius. During each Strombolian period, estimates of bubble length and overpressure are calculated. Using an alternate method based on acoustic power, we estimate gas velocity to be 30-60 m/s, in very good agreement with synthetic waveforms. Although there is some variation within these parameters, bubble length and overpressure for the first Strombolian phase are found to be ??? 82 ?? 11 m and 0.083 MPa. For the second Strombolian phase, bubble length and overpressure are estimated at 24 ?? 12 m and 0.15 MPa for the first 17 h after which bubble overpressure shows a constant increase, reaching a peak of 1.4 MPa, just prior to the end of the second Strombolian phase. This peak suggests that, at the time, the magma in the conduit may contain a relatively large concentration of small bubbles. Maximum total gas volume and gas fluxes at the surface are estimated to be 3.3 ?? 107 and 2.9 ?? 103 m3/s for the first phase and 1.0 ?? 108 and 2.2 ?? 103 m3/s for the second phase. This gives a mass flux of 1.2 ?? 103 and 8.7 ?? 102 kg/s, respectively, for the first and the second Strombolian phases. ?? 2004 Elsevier B.V. All rights reserved.

  14. System and method for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate sound sources

    DOEpatents

    Holzrichter, John F.; Burnett, Greg C.; Ng, Lawrence C.

    2007-10-16

    A system and method for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate sound sources is disclosed. Propagating wave electromagnetic sensors monitor excitation sources in sound producing systems, such as machines, musical instruments, and various other structures. Acoustical output from these sound producing systems is also monitored. From such information, a transfer function characterizing the sound producing system is generated. From the transfer function, acoustical output from the sound producing system may be synthesized or canceled. The methods disclosed enable accurate calculation of matched transfer functions relating specific excitations to specific acoustical outputs. Knowledge of such signals and functions can be used to effect various sound replication, sound source identification, and sound cancellation applications.

  15. System and method for characterizing synthesizing and/or canceling out acoustic signals from inanimate sound sources

    DOEpatents

    Holzrichter, John F.; Burnett, Greg C.; Ng, Lawrence C.

    2003-01-01

    A system and method for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate sound sources is disclosed. Propagating wave electromagnetic sensors monitor excitation sources in sound producing systems, such as machines, musical instruments, and various other structures. Acoustical output from these sound producing systems is also monitored. From such information, a transfer function characterizing the sound producing system is generated. From the transfer function, acoustical output from the sound producing system may be synthesized or canceled. The methods disclosed enable accurate calculation of matched transfer functions relating specific excitations to specific acoustical outputs. Knowledge of such signals and functions can be used to effect various sound replication, sound source identification, and sound cancellation applications.

  16. System and method for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate sound sources

    DOEpatents

    Holzrichter, John F; Burnett, Greg C; Ng, Lawrence C

    2013-05-21

    A system and method for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate sound sources is disclosed. Propagating wave electromagnetic sensors monitor excitation sources in sound producing systems, such as machines, musical instruments, and various other structures. Acoustical output from these sound producing systems is also monitored. From such information, a transfer function characterizing the sound producing system is generated. From the transfer function, acoustical output from the sound producing system may be synthesized or canceled. The methods disclosed enable accurate calculation of matched transfer functions relating specific excitations to specific acoustical outputs. Knowledge of such signals and functions can be used to effect various sound replication, sound source identification, and sound cancellation applications.

  17. Ample active acoustic space of a frog from the South American temperate forest.

    PubMed

    Penna, Mario; Moreno-Gómez, Felipe N

    2014-03-01

    The efficiency of acoustic communication depends on the power generated by the sound source, the attributes of the environment across which signals propagate, the environmental noise and the sensitivity of the intended receivers. Eupsophus emiliopugini, an anuran from the temperate austral forest communicates by means of an advertisement call of moderate intensity within the range for anurans. To estimate the range over which these frogs communicate effectively, we conducted measurements of call sound levels and of auditory thresholds to pure tones and to synthetic conspecific calls. The results show that E. emiliopugini produces advertisement calls of about 84 dB SPL at 0.25 m from the caller. The signals are affected by attenuation as they propagate, reaching average values of about 47 dB SPL at 8 m from the sound source. Midbrain multi-unit recordings show quite sensitive audiograms within the anuran range, with thresholds of about 44 dB SPL for synthetic imitations of conspecific calls, which would allow communication at distances beyond 8 m. This is an extended range as compared to E. calcaratus, a related syntopic species for which a previous study has shown to be restricted to active acoustic spaces shorter than 2 m. The comparison reveals divergent strategies for related taxa communicating amid the same environment. PMID:24356786

  18. Reflection and refraction of acoustic waves at the interface between a gas and a disperse systems

    NASA Astrophysics Data System (ADS)

    Shagapov, V. Sh.; Sarapulova, V. V.

    2015-09-01

    The reflection and refraction of acoustic waves at different angles of incidence on the interface between a vapor-gas-droplet system and air are studied. From an analysis of analytical solutions, it has been found that in the case of incidence on the interface from the side of the vapor-gas-droplet medium, there is a critical angle of incidence at which the wave is completely reflected from the boundary, i.e., total internal reflection takes place. It is shown that for a certain angle of incidence on the interface both from the air side and from the mixture side and for a certain volume fraction of water in the disperse system, complete transmission of the acoustic wave through the medium is observed.

  19. System and method for investigating sub-surface features of a rock formation with acoustic sources generating coded signals

    SciTech Connect

    Vu, Cung Khac; Nihei, Kurt; Johnson, Paul A; Guyer, Robert; Ten Cate, James A; Le Bas, Pierre-Yves; Larmat, Carene S

    2014-12-30

    A system and a method for investigating rock formations includes generating, by a first acoustic source, a first acoustic signal comprising a first plurality of pulses, each pulse including a first modulated signal at a central frequency; and generating, by a second acoustic source, a second acoustic signal comprising a second plurality of pulses. A receiver arranged within the borehole receives a detected signal including a signal being generated by a non-linear mixing process from the first-and-second acoustic signal in a non-linear mixing zone within the intersection volume. The method also includes-processing the received signal to extract the signal generated by the non-linear mixing process over noise or over signals generated by a linear interaction process, or both.

  20. Implantable acoustic-beacon automatic fish-tracking system

    NASA Technical Reports Server (NTRS)

    Mayhue, R. J.; Lovelady, R. W.; Ferguson, R. L.; Richards, C. E.

    1977-01-01

    A portable automatic fish tracking system was developed for monitoring the two dimensional movements of small fish within fixed areas of estuarine waters and lakes. By using the miniature pinger previously developed for this application, prototype tests of the system were conducted in the York River near the Virginia Institute of Marine Science with two underwater listening stations. Results from these tests showed that the tracking system could position the miniature pinger signals to within + or - 2.5 deg and + or - 135 m at ranges up to 2.5 km. The pingers were implanted in small fish and were successfully tracked at comparable ranges. No changes in either fish behavior or pinger performance were observed as a result of the implantation. Based on results from these prototype tests, it is concluded that the now commercially available system provides an effective approach to underwater tracking of small fish within a fixed area of interest.

  1. A Hardware-and-Software System for Experimental Studies of the Acoustic Startle Response in Laboratory Rodents.

    PubMed

    Pevtsov, E F; Storozheva, Z I; Proshin, A T; Pevtsova, E I

    2016-02-01

    We developed and tested a novel hardware-and-software system for recording the amplitude of the acoustic startle response in rodents. In our experiments, the baseline indexes of acoustic startle response in laboratory rats and pre-stimulation inhibition under the standard delivery of acoustic stimulation were similar to those evaluated by other investigators on foreign devices. The proposed system is relatively cheap and provides the possibility of performing experiments on freely moving specimens. It should be emphasized that the results of studies can be processed with free-access software. PMID:26902348

  2. Acoustic neuroma

    MedlinePlus

    Vestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor ... Acoustic neuromas have been linked with the genetic disorder neurofibromatosis type 2 (NF2). Acoustic neuromas are uncommon.

  3. The Impact of Model Uncertainty on Spatial Compensation in Active Structural Acoustic Control

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    Turbulent boundary layer (TBL) noise is considered a primary factor in the interior noise experienced by passengers aboard commercial airliners. There have been numerous investigations of interior noise control devoted to aircraft panels; however, practical realization is a challenge since the physical boundary conditions are uncertain at best. In most prior studies, pinned or clamped boundary conditions have been assumed; however, realistic panels likely display a range of varying 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 actuators and sensors required to achieve the desired control. The impact of model uncertainties, uncertain boundary conditions in particular, on the selection of actuator and sensor locations for structural acoustic control are considered herein. Results from this research effort indicate that it is possible to optimize the design of actuator and sensor location and aperture, which minimizes the impact of boundary conditions on the desired structural acoustic control.

  4. Acoustic Doppler velocity measurement system using capacitive micromachined ultrasound transducer array technology.

    PubMed

    Shin, Minchul; Krause, Joshua S; DeBitetto, Paul; White, Robert D

    2013-08-01

    This paper describes the design, fabrication, modeling, and characterization of a small (1 cm(2) transducer chip) acoustic Doppler velocity measurement system using microelectromechanical systems capacitive micromachined ultrasound transducer (cMUT) array technology. The cMUT sensor has a 185 kHz resonant frequency to achieve a 13° beam width for a 1 cm aperture. A model for the cMUT and the acoustic system which includes electrical, mechanical, and acoustic components is provided. Furthermore, this paper shows characterization of the cMUT sensor with a variety of testing procedures including Laser Doppler Vibrometry (LDV), beampattern measurement, reflection testing, and velocity testing. LDV measurements demonstrate that the membrane displacement at the center point is 0.4 nm/V(2) at 185 kHz. The maximum range of the sensor is 60 cm (30 cm out and 30 cm back). A velocity sled was constructed and used to demonstrate measureable Doppler shifts at velocities from 0.2 to 1.0 m/s. The Doppler shifts agree well with the expected frequency shifts over this range. PMID:23927100

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Experimental research of the Multi-frequency Acoustic Backscatter System using the field sediment

    NASA Astrophysics Data System (ADS)

    Zhang, wenxiang

    2014-05-01

    The measurements of suspended sediment concentration and particle size profiles are very important to the engineering and environmental applications, especially in the estuarine and coastal areas. In recent years acoustic method has obtained increasing acceptance by many researchers. The theory of this method for measuring them is based on the acoustic backscattering and attenuation properties of the sediment in suspension. The Multi-frequency Acoustic Backscatter System (MABS), which has four acoustic sensors with different frequencies, can be measuring the profiles in the shallow water environment (no more than 10 meters). The experiments were conducted for AQUAscat1000 (MABS) (Made in UK) by the 'test tower' (φ600mm by 1500mm) in Laboratory. The frequency of the acoustic transducer is 0.5MHz, 1MHz, 2MHz and 4MHz, respectively. Two different places sediment were obtained from the Yangtze estuary. The average particle size is about 15μm and 115μm, respectively. Suspended sediment concentration in the 'test tower' was relatively constant during each phase of the sampling. The experimental procedures were as follows: (1) obtaining the background value of the instrument system; (2) add the field sediment to the tower according to the weight and allowing the mixture to homogenize; (3) obtaining water samples in different depths from the 'test tower'; (4) analyzing the water samples. These preliminary results show that (1) the MABS sensors are estimated from a complex function, depending on the receiving information (Voltage), measured at range, the speed of sound in water and the attenuation of sound by water, the sediment density and radius, and backscattering property of the sediment; (2) the appropriate calibration and regression approaches should be selected so as to obtain the reliable results of suspended sediment concentration(**R2 >0.7) and particle size(**R2 >0.5) measurements; (3) the MABS could be applied in the relative fine sediment condition, and

  7. Method and system to synchronize acoustic therapy with ultrasound imaging

    NASA Technical Reports Server (NTRS)

    Owen, Neil (Inventor); Bailey, Michael R. (Inventor); Hossack, James (Inventor)

    2009-01-01

    Interference in ultrasound imaging when used in connection with high intensity focused ultrasound (HIFU) is avoided by employing a synchronization signal to control the HIFU signal. Unless the timing of the HIFU transducer is controlled, its output will substantially overwhelm the signal produced by ultrasound imaging system and obscure the image it produces. The synchronization signal employed to control the HIFU transducer is obtained without requiring modification of the ultrasound imaging system. Signals corresponding to scattered ultrasound imaging waves are collected using either the HIFU transducer or a dedicated receiver. A synchronization processor manipulates the scattered ultrasound imaging signals to achieve the synchronization signal, which is then used to control the HIFU bursts so as to substantially reduce or eliminate HIFU interference in the ultrasound image. The synchronization processor can alternatively be implemented using a computing device or an application-specific circuit.

  8. Solar cell activation system

    SciTech Connect

    Apelian, L.

    1983-07-05

    A system for activating solar cells involves the use of phosphorescent paint, the light from which is amplified by a thin magnifying lens and used to activate solar cells. In a typical system, a member painted with phosphorescent paint is mounted adjacent a thin magnifying lens which focuses the light on a predetermined array of sensitive cells such as selenium, cadmium or silicon, mounted on a plastic board. A one-sided mirror is mounted adjacent the cells to reflect the light back onto said cells for purposes of further intensification. The cells may be coupled to rechargeable batteries or used to directly power a small radio or watch.

  9. Nonlinear activity of acoustically driven gas bubble near a rigid boundary

    SciTech Connect

    Maksimov, Alexey

    2015-10-28

    The presence of a boundary can produce considerable changes in the oscillation amplitude of the bubble and its scattered echo. The present study fills a gap in the literature, in that it is concerned theoretically with the bubble activity at relatively small distances from the rigid boundary. It was shown that the bi-spherical coordinates provide separation of variables and are more suitable for analysis of the dynamics of these constrained bubbles. Explicit formulas have been derived which describe the dependence of the bubble emission near a rigid wall on its size and the separation distance between the bubble and the boundary. As applications, time reversal technique for gas leakage detection and radiation forces that are induced by an acoustic wave on a constrained bubble were analyzed.

  10. Surface acoustic wave regulated single photon emission from a coupled quantum dot-nanocavity system

    NASA Astrophysics Data System (ADS)

    Weiß, M.; Kapfinger, S.; Reichert, T.; Finley, J. J.; Wixforth, A.; Kaniber, M.; Krenner, H. J.

    2016-07-01

    A coupled quantum dot-nanocavity system in the weak coupling regime of cavity-quantumelectrodynamics is dynamically tuned in and out of resonance by the coherent elastic field of a fSAW ≃ 800 MHz surface acoustic wave. When the system is brought to resonance by the sound wave, light-matter interaction is strongly increased by the Purcell effect. This leads to a precisely timed single photon emission as confirmed by the second order photon correlation function, g(2). All relevant frequencies of our experiment are faithfully identified in the Fourier transform of g(2), demonstrating high fidelity regulation of the stream of single photons emitted by the system.

  11. Patterns of acoustical activity of bats prior to and following White-nose Syndrome occurrence

    USGS Publications Warehouse

    Ford, W. Mark; Britzke, Eric R.; Dobony, Christopher A.; Rodrigue, Jane L.; Johnson, Joshua B.

    2011-01-01

    White-nose Syndrome (WNS), a wildlife health concern that has decimated cave-hibernating bat populations in eastern North America since 2006, began affecting source-caves for summer bat populations at Fort Drum, a U.S. Army installation in New York in the winter of 2007–2008. As regional die-offs of bats became evident, and Fort Drum's known populations began showing declines, we examined whether WNS-induced change in abundance patterns and seasonal timing of bat activity could be quantified using acoustical surveys, 2003–2010, at structurally uncluttered riparian–water habitats (i.e., streams, ponds, and wet meadows). As predicted, we observed significant declines in overall summer activity between pre-WNS and post-WNS years for little brown bats Myotis lucifugus, northern bats M. septentrionalis, and Indiana bats M. sodalis. We did not observe any significant change in activity patterns between pre-WNS and post-WNS years for big brown bats Eptesicus fuscus, eastern red bats Lasiurus borealis, or the small number of tri-colored bats Perimyotis subflavus. Activity of silver-haired bats Lasionycteris noctivagans increased from pre-WNS to post-WNS years. Activity levels of hoary bats Lasiurus cinereus significantly declined between pre- and post-WNS years. As a nonhibernating, migratory species, hoary bat declines might be correlated with wind-energy development impacts occurring in the same time frame rather than WNS. Intraseason activity patterns also were affected by WNS, though the results were highly variable among species. Little brown bats showed an overall increase in activity from early to late summer pre-WNS, presumably due to detections of newly volant young added to the local population. However, the opposite occurred post-WNS, indicating that reproduction among surviving little brown bats may be declining. Our data suggest that acoustical monitoring during the summer season can provide insights into species' relative abundance on the

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

    PubMed Central

    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. PMID:22399990

  13. Estimation of the detection range of a hydroacoustic system based on the acoustic power flux receiver

    NASA Astrophysics Data System (ADS)

    Gordienko, V. A.; Krasnopistsev, N. V.; Nasedkin, A. V.; Nekrasov, V. N.

    2007-11-01

    Approaches to estimating the detection range of systems based on vector receivers are considered. The approaches rely on a detailed analysis of the process of signal’s acoustic power flux formation in the presence of ambient sea noise and uncover the signal information parameters at the receiver output that provide the required statistically confident range of weak signal detection under these conditions. Based on the sonar equations and the known fundamental relationships between the outputs of a pressure receiver and a vector receiver for signal and noise, estimates of the maximum possible gain in the detection range of an acoustic power flux receiver are considered as a function of anisotropy of the ambient noise field in the area.

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

    SciTech Connect

    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.

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

    PubMed Central

    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

  16. Parameter estimation in a structural acoustic system with fully nonlinear coupling conditions

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Smith, Ralph C.

    1994-01-01

    A methodology for estimating physical parameters in a class of structural acoustic systems is presented. The general model under consideration consists of an interior cavity which is separated from an exterior noise source by an enclosing elastic structure. Piezoceramic patches are bonded to or embedded in the structure; these can be used both as actuators and sensors in applications ranging from the control of interior noise levels to the determination of structural flaws through nondestructive evaluation techniques. The presence and excitation of patches, however, changes the geometry and material properties of the structure as well as involves unknown patch parameters, thus necessitating the development of parameter estimation techniques which are applicable in this coupled setting. In developing a framework for approximation, parameter estimation and implementation, strong consideration is given to the fact that the input operator is unbonded due to the discrete nature of the patches. Moreover, the model is weakly nonlinear. As a result of the coupling mechanism between the structural vibrations and the interior acoustic dynamics. Within this context, an illustrating model is given, well-posedness and approximations results are discussed and an applicable parameter estimation methodology is presented. The scheme is then illustrated through several numerical examples with simulations modeling a variety of commonly used structural acoustic techniques for systems excitations and data collection.

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

    NASA Astrophysics Data System (ADS)

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

    2005-09-01

    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.

  18. Optimization of computation efficiency in underwater acoustic navigation system.

    PubMed

    Lee, Hua

    2016-04-01

    This paper presents a technique for the estimation of the relative bearing angle between the unmanned underwater vehicle (UUV) and the base station for the homing and docking operations. The key requirement of this project includes computation efficiency and estimation accuracy for direct implementation onto the UUV electronic hardware, subject to the extreme constraints of physical limitation of the hardware due to the size and dimension of the UUV housing, electric power consumption for the requirement of UUV survey duration and range coverage, and heat dissipation of the hardware. Subsequent to the design and development of the algorithm, two phases of experiments were conducted to illustrate the feasibility and capability of this technique. The presentation of this paper includes system modeling, mathematical analysis, and results from laboratory experiments and full-scale sea tests. PMID:27106337

  19. Production Systems. Laboratory Activities.

    ERIC Educational Resources Information Center

    Gallaway, Ann, Ed.

    This production systems guide provides teachers with learning activities for secondary students. Introductory materials include an instructional planning outline and worksheet, an outline of essential elements, domains and objectives, a course description, and a content outline. The guide contains 30 modules on the following topics: production…

  20. Communication Systems. Laboratory Activities.

    ERIC Educational Resources Information Center

    Sutherland, Barbara, Ed.

    This communication systems guide provides teachers with learning activities for secondary students. Introductory materials include an instructional planning outline and worksheet, an outline of essential elements, a list of objectives, a course description, and a content outline. The guide contains 32 modules on the following topics: story…

  1. Acoustic Characteristics of Stridor in Multiple System Atrophy

    PubMed Central

    Lee, Jee Young; Joo, Eun Yeon; Nam, Hyunwoo

    2016-01-01

    Nocturnal stridor is a breathing disorder prevalent in patients with multiple system atrophy (MSA). An improved understanding of this breathing disorder is essential since nocturnal stridor carries a poor prognosis (an increased risk of sudden death). In this study, we aimed to classify types of stridor by sound analysis and to reveal their clinical significance. Patients who met the criteria for probable MSA and had undergone polysomnography (PSG) were recruited. Patients were then assessed clinically with sleep questionnaires, including the Pittsburgh Sleep Quality Index, and the Hoehn and Yahr scale. Nocturnal stridor and snoring were analyzed with the Multi-Dimensional Voice Program. Nocturnal stridor was recorded in 22 patients and snoring in 18 patients using the PSG. Waveforms of stridors were classified into rhythmic or semirhythmic after analysis of the oscillogram. Formants and harmonics were observed in both types of stridor, but not in snoring. Of the 22 patients diagnosed with stridor during the present study, fifteen have subsequently died, with the time to death after the PSG study being 1.9 ± 1.4 years (range 0.8 to 5.0 years). The rhythmic waveform group presented higher scores on the Hoehn and Yahr scale and the survival outcome of this group was lower compared to the semirhythmic waveform group (p = 0.030, p = 0.014). In the Kaplan Meier’s survival curve, the outcome of patients with rhythmic waveform was significantly less favorable than the outcome of patients with semirhythmic waveform (log-rank test, p < 0.001). Stridor in MSA can be classified into rhythmic and semirhythmic types and the rhythmic component signifies a poorer outcome. PMID:27093692

  2. Testing and verification of a scale-model acoustic propagation system.

    PubMed

    Sagers, Jason D; Ballard, Megan S

    2015-12-01

    This paper discusses the design and operation of a measurement apparatus used to conduct scale-model underwater acoustic propagation experiments, presents experimental results for an idealized waveguide, and compares the measured results to data generated by two-dimensional (2D) and three-dimensional (3D) numerical models. The main objective of this paper is to demonstrate the capability of the apparatus for a simple waveguide that primarily exhibits 2D acoustic propagation. The apparatus contains a computer-controlled positioning system that accurately moves a receiving transducer in the water layer above a scale-model bathymetry while a stationary source transducer emits broadband pulsed waveforms. Experimental results are shown for a 2.133 m × 1.219 m bathymetric part possessing a flat-bottom bathymetry with a translationally invariant wedge of 10° slope along one edge. Beamformed results from a synthetic horizontal line array indicate the presence of strong in-plane arrivals along with weaker diffracted and horizontally refracted arrivals. A simulated annealing inversion method is applied to infer values for five waveguide parameters with the largest measurement uncertainty. The inferred values are then used in a 2D method of images model and a 3D adiabatic normal-mode model to simulate the measured acoustic data. PMID:26723314

  3. Acoustic signature recognition technique for Human-Object Interactions (HOI) in persistent surveillance systems

    NASA Astrophysics Data System (ADS)

    Alkilani, Amjad; Shirkhodaie, Amir

    2013-05-01

    Handling, manipulation, and placement of objects, hereon called Human-Object Interaction (HOI), in the environment generate sounds. Such sounds are readily identifiable by the human hearing. However, in the presence of background environment noises, recognition of minute HOI sounds is challenging, though vital for improvement of multi-modality sensor data fusion in Persistent Surveillance Systems (PSS). Identification of HOI sound signatures can be used as precursors to detection of pertinent threats that otherwise other sensor modalities may miss to detect. In this paper, we present a robust method for detection and classification of HOI events via clustering of extracted features from training of HOI acoustic sound waves. In this approach, salient sound events are preliminary identified and segmented from background via a sound energy tracking method. Upon this segmentation, frequency spectral pattern of each sound event is modeled and its features are extracted to form a feature vector for training. To reduce dimensionality of training feature space, a Principal Component Analysis (PCA) technique is employed to expedite fast classification of test feature vectors, a kd-tree and Random Forest classifiers are trained for rapid classification of training sound waves. Each classifiers employs different similarity distance matching technique for classification. Performance evaluations of classifiers are compared for classification of a batch of training HOI acoustic signatures. Furthermore, to facilitate semantic annotation of acoustic sound events, a scheme based on Transducer Mockup Language (TML) is proposed. The results demonstrate the proposed approach is both reliable and effective, and can be extended to future PSS applications.

  4. Acoustic biosensors

    PubMed Central

    Fogel, Ronen; Seshia, Ashwin A.

    2016-01-01

    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. PMID:27365040

  5. Acoustic biosensors.

    PubMed

    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. PMID:27365040

  6. Active induction of in vivo microbubbles by acoustic radiation force at the bifurcation of blood vessel and its evaluation.

    PubMed

    Masuda, Kohji; Koido, Jun; Miyazawa, Shinya; Wada, Hikaru; Hosaka, Naoto; Mochizuki, Takashi

    2015-08-01

    Alhough the development of drug delivery system using microbubbles and ultrasound is expected, because microbubbles diffuse in bloodstream, we have so far reported our attempts for active control of the microbubbles in flow by acoustic radiation force in order to increase local concentration of the microbubbles. However, there was no evidence that in vivo microbubbles act as similar as in vitro experiments, because there were limitations for reproduction of in vivo conditions. In this study, we have elucidated the relationship between brightness variation and microbubbles concentration in the suspension to estimate the absolute concentration in an invisible condition considering in vivo experiment. Then we conducted an experiment of active induction of microbubbles in a Y-form bifurcation of artificial blood vessel, where experimental conditions were with focused ultrasound, the central frequency of 5 MHz, flow velocity of 30 mm/s, and maximum sound pressure of 300 kPa-pp, respectively. Then we applied the conditions for active induction of in vivo microbubbles to compare with in vitro experiments. We used a bifurcation of blood vessel in an ear of a rabbit because the bifurcation shape in its blood vessel is visible. As the results of the experiment, the microbubbles concentration in the induced path was almost two times higher than that in the other path, which agrees with the results from in vitro experiments. PMID:26736523

  7. Numerical simulation of geodesic acoustic modes in a multi-ion system

    SciTech Connect

    Ye, Lei; Guo, Wenfeng; Xiao, Xiaotao; Wang, Shaojie

    2013-07-15

    Based on the semi-Lagrangian method, a δf drift kinetic continuum code incorporating magnetic flux coordinate was developed and applied to investigate the geodesic acoustic mode (GAM) oscillation in a multi-ion plasma system. This work proves clearly that the effective ion mass number affects the GAM in a multi-ion system. In this simulation, GAM frequency and damping rate are seen to vary with the proportion of impurity ions. The numerical result is consistent with the theoretical prediction in terms of both frequency and damping rate.

  8. Characterisation and testing of the KM3NeT acoustic positioning system

    NASA Astrophysics Data System (ADS)

    Viola, S.; Simeone, F.; Saldaña, M.

    2016-04-01

    In underwater neutrino telescopes, the search of point-like sources through the Cherenkov detection technique requires a precise knowledge of the positions of thousands of optical sensors, spread in a volume of a few cubic kilometres. In KM3NeT the optical sensors are hosted in 700 m high semi-rigid structures, called detection units, which move under the effects of underwater currents. These movements are continuously monitored through an underwater positioning system based on acoustic emitters and receivers. In this work, the tests performed on the key elements of the positioning system are presented.

  9. A smart pattern recognition system for the automatic identification of aerospace acoustic sources

    NASA Technical Reports Server (NTRS)

    Cabell, R. H.; Fuller, C. R.

    1989-01-01

    An intelligent air-noise recognition system is described that uses pattern recognition techniques to distinguish noise signatures of five different types of acoustic sources, including jet planes, propeller planes, a helicopter, train, and wind turbine. Information for classification is calculated using the power spectral density and autocorrelation taken from the output of a single microphone. Using this system, as many as 90 percent of test recordings were correctly identified, indicating that the linear discriminant functions developed can be used for aerospace source identification.

  10. Focus Adjustment System of Laser Probe for Radio Frequency Surface and Bulk Acoustic Wave Devices

    NASA Astrophysics Data System (ADS)

    Wu, Nan; Kashiwa, Keisuke; Hashimoto, Ken-ya; Omori, Tatsuya; Yamaguchi, Masatsune; Kasai, Naoki

    2009-10-01

    In this paper, we describe a focus adjustment system designed especially for a fast-mechanical-scanning laser probe for radio-frequency surface and bulk acoustic wave devices. When high spatial resolution is necessary for the observation, one needs an objective lens of large magnifying power with extremely shallow focal depth. Then, a small inclination of a measurement device may cause severe defocus resulting in blurred images. We installed the focus adjustment system in the laser probe, and showed that even with inclination, high-quality information of the wave field can be acquired without reducing the scanning speed.

  11. Passive pavement-mounted acoustical linguistic drive alert system and method

    DOEpatents

    Kisner, Roger A.; Anderson, Richard L.; Carnal, Charles L.; Hylton, James O.; Stevens, Samuel S.

    2001-01-01

    Systems and methods are described for passive pavement-mounted acoustical alert of the occupants of a vehicle. A method of notifying a vehicle occupant includes providing a driving medium upon which a vehicle is to be driven; and texturing a portion of the driving medium such that the textured portion interacts with the vehicle to produce audible signals, the textured portion pattern such that a linguistic message is encoded into the audible signals. The systems and methods provide advantages because information can be conveyed to the occupants of the vehicle based on the location of the vehicle relative to the textured surface.

  12. Effects of acoustic hood on noise, CFC-11, and particulate matter in a recycling system for waste refrigerator cabinet.

    PubMed

    Guo, Jie; Fang, Wenxiong; Yang, Yichen; Xu, Zhenming

    2014-11-01

    The mechanical-physical process was proven to be technologically feasible for waste refrigerator recycling and has been widely used in the typical e-waste recycling factories in China. In this study, effects of the acoustic hood on the reduction of noise level, CFC-11, and heavy metals (Cr, Ni, Cu, Cd, and Pb) in particulate matter (PM) were evaluated. For noise pollution, the noise level inside and outside the acoustic hood was 96.4 and 78.9 dB, respectively. Meanwhile, it had a significant effect on A-weighted sound level with a reduction from 98.3 to 63.6 dB. For CFC-11 exposure, abundant CFC-11 (255 mg/m(3)) was detected in the acoustic hood. However, the mean concentration of CFC-11 at the outline of polyurethane foam collection was obviously diminished to 14 mg/m(3), and no CFC-11 was monitored around the acoustic hood. The concentrations of PM and heavy metals in PM outside the acoustic hood were lower than those inside the acoustic hood due to the physical barriers of the acoustic hood. Based on the risk assessment, only adverse health effect caused by Pb might likely appear. All the results can provide the basic data for pollution control and risk assessment in waste refrigerator recycling system. PMID:24965005

  13. Real-time analysis system for gas turbine ground test acoustic measurements.

    PubMed

    Johnston, Robert T

    2003-10-01

    This paper provides an overview of a data system upgrade to the Pratt and Whitney facility designed for making acoustic measurements on aircraft gas turbine engines. A data system upgrade was undertaken because the return-on-investment was determined to be extremely high. That is, the savings on the first test series recovered the cost of the hardware. The commercial system selected for this application utilizes 48 input channels, which allows either 1/3 octave and/or narrow-band analyses to be preformed real-time. A high-speed disk drive allows raw data from all 48 channels to be stored simultaneously while the analyses are being preformed. Results of tests to ensure compliance of the new system with regulations and with existing systems are presented. Test times were reduced from 5 h to 1 h of engine run time per engine configuration by the introduction of this new system. Conservative cost reduction estimates for future acoustic testing are 75% on items related to engine run time and 50% on items related to the overall length of the test. PMID:14582877

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

    NASA Technical Reports Server (NTRS)

    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

  15. Wind Turbine Generator System Acoustic Noise Test Report for the Gaia Wind 11-kW Wind Turbine

    SciTech Connect

    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.

  16. Adaptive neuro-fuzzy inference system for acoustic analysis of 4-channel phonocardiograms using empirical mode decomposition.

    PubMed

    Becerra, Miguel A; Orrego, Diana A; Delgado-Trejos, Edilson

    2013-01-01

    The heart's mechanical activity can be appraised by auscultation recordings, taken from the 4-Standard Auscultation Areas (4-SAA), one for each cardiac valve, as there are invisible murmurs when a single area is examined. This paper presents an effective approach for cardiac murmur detection based on adaptive neuro-fuzzy inference systems (ANFIS) over acoustic representations derived from Empirical Mode Decomposition (EMD) and Hilbert-Huang Transform (HHT) of 4-channel phonocardiograms (4-PCG). The 4-PCG database belongs to the National University of Colombia. Mel-Frequency Cepstral Coefficients (MFCC) and statistical moments of HHT were estimated on the combination of different intrinsic mode functions (IMFs). A fuzzy-rough feature selection (FRFS) was applied in order to reduce complexity. An ANFIS network was implemented on the feature space, randomly initialized, adjusted using heuristic rules and trained using a hybrid learning algorithm made up by least squares and gradient descent. Global classification for 4-SAA was around 98.9% with satisfactory sensitivity and specificity, using a 50-fold cross-validation procedure (70/30 split). The representation capability of the EMD technique applied to 4-PCG and the neuro-fuzzy inference of acoustic features offered a high performance to detect cardiac murmurs. PMID:24109851

  17. Modeling the Behavior of an Underwater Acoustic Relative Positioning System Based on Complementary Set of Sequences

    PubMed Central

    Aparicio, Joaquín; Jiménez, Ana; Álvarez, Fernando J.; Ureña, Jesús; De Marziani, Carlos; Diego, Cristina

    2011-01-01

    The great variability usually found in underwater media makes modeling a challenging task, but helpful for better understanding or predicting the performance of future deployed systems. In this work, an underwater acoustic propagation model is presented. This model obtains the multipath structure by means of the ray tracing technique. Using this model, the behavior of a relative positioning system is presented. One of the main advantages of relative positioning systems is that only the distances between all the buoys are needed to obtain their positions. In order to obtain the distances, the propagation times of acoustic signals coded by Complementary Set of Sequences (CSS) are used. In this case, the arrival instants are obtained by means of correlation processes. The distances are then used to obtain the position of the buoys by means of the Multidimensional Scaling Technique (MDS). As an early example of an application using this relative positioning system, a tracking of the position of the buoys at different times is performed. With this tracking, the surface current of a particular region could be studied. The performance of the system is evaluated in terms of the distance from the real position to the estimated one. PMID:22247661

  18. Modeling the behavior of an underwater acoustic relative positioning system based on complementary set of sequences.

    PubMed

    Aparicio, Joaquín; Jiménez, Ana; Alvarez, Fernando J; Ureña, Jesús; De Marziani, Carlos; Diego, Cristina

    2011-01-01

    The great variability usually found in underwater media makes modeling a challenging task, but helpful for better understanding or predicting the performance of future deployed systems. In this work, an underwater acoustic propagation model is presented. This model obtains the multipath structure by means of the ray tracing technique. Using this model, the behavior of a relative positioning system is presented. One of the main advantages of relative positioning systems is that only the distances between all the buoys are needed to obtain their positions. In order to obtain the distances, the propagation times of acoustic signals coded by Complementary Set of Sequences (CSS) are used. In this case, the arrival instants are obtained by means of correlation processes. The distances are then used to obtain the position of the buoys by means of the Multidimensional Scaling Technique (MDS). As an early example of an application using this relative positioning system, a tracking of the position of the buoys at different times is performed. With this tracking, the surface current of a particular region could be studied. The performance of the system is evaluated in terms of the distance from the real position to the estimated one. PMID:22247661

  19. On the acoustic analysis and optimization of ducted ventilation systems using a sub-structuring approach.

    PubMed

    Yu, X; Cui, F S; Cheng, L

    2016-01-01

    This paper presents a general sub-structuring approach to predict the acoustic performance of ducted ventilation systems. The modeling principle is to determine the subsystem characteristics by calculating the transfer functions at their coupling interfaces, and the assembly is enabled by using a patch-based interface matching technique. For a particular example of a bended ventilation duct connecting an inlet and an outlet acoustic domain, a numerical model is developed to predict its sound attenuation performance. The prediction accuracy is thoroughly validated against finite element models. Through numerical examples, the rigid-walled duct is shown to provide relatively weak transmission loss (TL) across the frequency range of interest, and exhibit only the reactive behavior for sound reflection. By integrating sound absorbing treatment such as micro-perforated absorbers into the system, the TL can be significantly improved, and the system is seen to exhibit hybrid mechanisms for sound attenuation. The dissipative effect dominates at frequencies where the absorber is designed to be effective, and the reactive effect provides compensations at the absorption valleys attributed to the resonant behavior of the absorber. This ultimately maintains the system TL at a relatively high level across the entire frequency of interest. The TL of the system can be tuned or optimized in a very efficient way using the proposed approach due to its modular nature. It is shown that a balance of the hybrid mechanism is important to achieve an overall broadband attenuation performance in the design frequency range. PMID:26827024

  20. ADASY (Active Daylighting System)

    NASA Astrophysics Data System (ADS)

    Vázquez-Moliní, Daniel; González-Montes, Mario; Fernández-Balbuena, Antonio Á.; Bernabéu, Eusebio; García-Botella, Ángel; García-Rodríguez, Lucas; Pohl, Wilfried

    2009-08-01

    The main objective of ADASY (Active Daylighting System) work is to design a façade static daylighting system oriented to office applications, mainly. The goal of the project is to save energy by guiding daylight into a building for lighting purpose. With this approach we can reduce the electrical load for artificial lighting, completing it with sustainable energy. The collector of the system is integrated on a vertical façade and its distribution guide is always horizontal inside of the false ceiling. ADASY is designed with a specific patent pending caption system, a modular light-guide and light extractor luminaire system. Special care has been put on the final cost of the system and its building integration purpose. The current ADASY configuration is able to illuminate 40 m2 area with a 300lx-400lx level in the mid time work hours; furthermore it has a good enough spatial uniformity distribution and a controlled glare. The data presented in this study are the result of simulation models and have been confirmed by a physical scaled prototype. ADASY's main advantages over regular illumination systems are: -Low maintenance; it has not mobile pieces and therefore it lasts for a long time and require little attention once installed. - No energy consumption; solar light continue working even if there has been a power outage. - High quality of light: the colour rendering of light is very high - Psychological benefits: People working with daylight get less stress and more comfort, increasing productivity. - Health benefits

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

    NASA Technical Reports Server (NTRS)

    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.

  2. Acoustic transducer for acoustic microscopy

    DOEpatents

    Khuri-Yakub, Butrus T.; Chou, Ching H.

    1990-01-01

    A shear acoustic transducer-lens system in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens.

  3. Acoustic transducer for acoustic microscopy

    DOEpatents

    Khuri-Yakub, B.T.; Chou, C.H.

    1990-03-20

    A shear acoustic transducer-lens system is described in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens. 9 figs.

  4. Sound reproduction in personal audio systems using the least-squares approach with acoustic contrast control constraint.

    PubMed

    Cai, Yefeng; Wu, Ming; Yang, Jun

    2014-02-01

    This paper describes a method for focusing the reproduced sound in the bright zone without disturbing other people in the dark zone in personal audio systems. The proposed method combines the least-squares and acoustic contrast criteria. A constrained parameter is introduced to tune the balance between two performance indices, namely, the acoustic contrast and the spatial average error. An efficient implementation of this method using convex optimization is presented. Offline simulations and real-time experiments using a linear loudspeaker array are conducted to evaluate the performance of the presented method. Results show that compared with the traditional acoustic contrast control method, the proposed method can improve the flatness of response in the bright zone by sacrificing the level of acoustic contrast. PMID:25234882

  5. Effects of unilateral acoustic trauma on tinnitus-related spontaneous activity in the inferior colliculus.

    PubMed

    Ropp, Tessa-Jonne F; Tiedemann, Kerrie L; Young, Eric D; May, Bradford J

    2014-12-01

    This study describes the long-term effects of sound-induced cochlear trauma on spontaneous discharge rates in the central nucleus of the inferior colliculus (ICC). As in previous studies, single-unit recordings in Sprague-Dawley rats revealed pervasive increases in spontaneous discharge rates. Based on differences in their sources of input, it was hypothesized that physiologically defined neural populations of the auditory midbrain would reveal the brainstem sources that dictate ICC hyperactivity. Abnormal spontaneous activity was restricted to target neurons of the ventral cochlear nucleus. Nearly identical patterns of hyperactivity were observed in the contralateral and ipsilateral ICC. The elevation in spontaneous activity extended to frequencies well below and above the region of maximum threshold shift. This lack of frequency organization suggests that ICC hyperactivity may be influenced by regions of the brainstem that are not tonotopically organized. Sound-induced hyperactivity is often observed in animals with behavioral signs of tinnitus. Prior to electrophysiological recording, rats were screened for tinnitus by measuring gap pre-pulse inhibition of the acoustic startle reflex (GPIASR). Rats with positive phenotypes did not exhibit unique patterns of ICC hyperactivity. This ambiguity raises concerns regarding animal behavioral models of tinnitus. If our screening procedures were valid, ICC hyperactivity is observed in animals without behavioral indications of the disorder. Alternatively, if the perception of tinnitus is strictly linked to ongoing ICC hyperactivity, our current behavioral approach failed to provide a reliable assessment of tinnitus state. PMID:25255865

  6. Changes in spontaneous neural activity immediately after an acoustic trauma: implications for neural correlates of tinnitus.

    PubMed

    Noreña, A J; Eggermont, J J

    2003-09-01

    Changes in spontaneous activity, recorded over 15-min periods before, immediately after and within hours after an acute acoustic trauma, were studied in primary auditory cortex of ketamine-anesthetized cats. We focused on the spontaneous firing rate (SFR), the peak cross-correlation coefficient (rho) and burst-firing activity. Multi-units (MUs) were grouped according to characteristic frequency (CF): MUs with a CF below the trauma-tone frequency (TF) were labeled as Be, those with a CF within 1 octave above the TF were labeled as Ab1 and those with a CF more than 1 octave above the TF were labeled as Ab2. Immediately after the trauma, the SFR was not significantly changed. The percentage of time that neurons were bursting, the mean burst duration, the number of spikes per burst and the mean inter-spike interval in a burst were enhanced. rho was locally increased in the Ab1-Ab2 and Ab2-Ab2 groups. A few hours post trauma, the SFR was increased in the Be and Ab2 groups, whereas burst-firing returned to pre-exposure levels. Moreover, rho was elevated in the Be-Ab2, Ab1-Ab2 and Ab2-Ab2 groups; this increase was significantly correlated to the changes in SFR. The results are discussed in the context of a neural correlate of tinnitus. PMID:13679145

  7. Experimental evaluation on the effectiveness of acoustic-laser technique towards the FRP-bonded concrete system

    NASA Astrophysics Data System (ADS)

    Qiu, Qiwen; Lau, Denvid

    2015-04-01

    Nondestructive evaluation (NDE) is essential for the detection of defects in the externally bonded fiber reinforced polymer (FRP) concrete, especially such bonded system can be readily found in strengthened and retrofitted structures nowadays. Among all the current NDE methods, acoustic-laser technique is a non-contact methodology with a high applicability to detect near-surface defect in composite structures, which is very suitable to be used for detecting defect in FRP retrofitted and strengthened concrete structures. The methodology is based on the acoustic excitation on the target surface and the measurement of its vibration using laser beam. To our best knowledge, no comprehensive study has been conducted to examine how the acoustic location and other related parameters affect the measurement sensitivity. In fact, several operational parameters affecting the performance of the test system are discussed here including (i) distance between the acoustic source and the object, (ii) sound pressure level (SPL), (iii) angle of the laser beam incidence and (iv) angle of the acoustic incidence. Here, we perform a series of parametric studies against these four operational parameters. Based on our experimental measurements, all parameters show significant effects on the measurement sensitivity of the acoustic-laser technique. Recommendations on an optimal range of each concerned parameter are provided.

  8. Ice/berm interaction study using rotary sidescan sonar and acoustic profiling systems

    SciTech Connect

    Good, R.R.; Anderson, K.G.; Lanzier, H.H.

    1984-05-01

    Tarsiut Island, in the Canadian Beaufort Sea, was the first dredged caisson retained island built for exploration drilling operations in the Arctic offshore. Due to the island's configuration location, a large first-year ice rubble pile would result from the ice/structure interaction. This paper outlines how a rotary side-scan sonar and a mechanically scanning, narrow-beam acoustic profiling system were used to determine the geometry and the contact area of the underside of heavily rubbled first-year ice. The results of this study are to be used to further the understanding of the nature and mechanism of the ice/structure interaction in Arctic offshore structures.

  9. Dispersion of low frequency surface acoustic waves of different polarizations in multilayered systems

    NASA Astrophysics Data System (ADS)

    Kosachev, V. V.; Shchegrov, A. V.

    1995-02-01

    Dispersion of surface acoustic waves (SAW) of sagittal and shear horizontal (SH) polarizations in a multilayered system of n isotropic layers on an isotropic substrate is investigated by the technique of effective boundary conditions in the framework of perturbation theory. The ratio of the total layer thickness to the wavelength of SAW is chosen to be a small parameter. Under such assumptions the dispersion relations for the SAW of both sagittal and SH-polarizations are derived. The results for sagittally polarized SAW derived by means of perturbation theory are compared with numerical solution for a bilayered structure. Possible applications of the results obtained are discussed.

  10. Acoustic mapping of shallow water gas releases using shipborne multibeam systems

    NASA Astrophysics Data System (ADS)

    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.

  11. A prototype system of microwave induced thermo-acoustic tomography for breast tumor.

    PubMed

    Zhu, Xiaozhang; Zhao, Zhiqin; Yang, Kai; Nie, Zaiping; Liu, Qinghuo

    2012-01-01

    Microwave-induced thermo-acoustic tomography (MITAT) is an innovative technique for tumor's detection. Due to there has high contrast in terms with permittivity and electrical conductivity of tumor versus normal tissue, even if the tumor still in the early phase it can be imaged clearly. For the proposed MITAT system, low energy microwave pulses are used as the irradiating signals, while the received signals are ultrasound, high contrast and high resolution images can be obtained. After some theoretical research and basic fundamental experiments, the first prototype of experimental system is designed and built. It includes the microwave radiator, the arrayed sensor bowl, the circular scanning platform, the system controller and the signal processor. Based on the experimental results using this integral MITAT clinic system, the images contrast can be reached higher than 383:1; while the sub-millimeter special resolution is obtained for a 1cm(3) scale tumor mimic. PMID:23365929

  12. Prediction of thermal acoustic oscillations (TAOs) in the CLAES solid CO2/neon system

    NASA Technical Reports Server (NTRS)

    Spradley, I. E.; Yuan, S. W. K.

    1991-01-01

    Results are presented of a study initiated to investigate the possibility that the existence of thermal acoustic oscillations (TAOs) in the Cryogenic Limb Atmospheric Etalon Spectrometer (CLAES) neon plumbing system ground configuration could be the cause of higher-than-predicted heat rates measured during thermal ground testing. Tests were conducted between warm boundary temperatures ranging from 40 to 100 K, which simulated the actual test conditions of the CLAES CO2/neon system. TAOs were observed between 6 and 106 Torr, which agreed with the analytical predictions, and verified the possible existence of TAOs in the CLAES system during ground testing. The presence of TAOs was eventually confirmed in the CLAES system during a subsequent thermal test and were determined to have caused the higher heat rates measured during the prior thermal test.

  13. Multiplex transmission system for gate drive signals of inverter circuit using surface acoustic wave filters

    NASA Astrophysics Data System (ADS)

    Suzuki, Akifumi; Ueda, Kensuke; Goka, Shigeyoshi; Wada, Keiji; Kakio, Shoji

    2016-07-01

    We propose and fabricate a multiplexed transmission system based on frequency-division multiple access (FDMA) with surface acoustic wave (SAW) filters. SAW filters are suitable for use in wide-gap switching devices and multilevel inverters because of their capability to operate at high temperatures, good electrical isolation, low cost, and high reliability. Our proposed system reduces the number of electrical signal wires needed to control each switching device and eliminates the need for isolation circuits, simplifying the transmission system and gate drive circuits. We successfully controlled two switching devices with a single coaxial line and confirmed the operation of a single-phase half-bridge inverter at a supply voltage of 100 V, and the total delay time to control the switching devices was less than 2.5 µs. Our experimental results validated our proposed system.

  14. Neutron activation analysis system

    DOEpatents

    Taylor, M.C.; Rhodes, J.R.

    1973-12-25

    A neutron activation analysis system for monitoring a generally fluid media, such as slurries, solutions, and fluidized powders, including two separate conduit loops for circulating fluid samples within the range of radiation sources and detectors is described. Associated with the first loop is a neutron source that emits s high flux of slow and thermal neutrons. The second loop employs a fast neutron source, the flux from which is substantially free of thermal neutrons. Adjacent to both loops are gamma counters for spectrographic determination of the fluid constituents. Other gsmma sources and detectors are arranged across a portion of each loop for deterMining the fluid density. (Official Gazette)

  15. Virtual acoustics for music practice rooms

    NASA Astrophysics Data System (ADS)

    Freiheit, Ron

    2003-04-01

    The use of virtual acoustics has provided a new level of practice experience for the musician. By integrating the sound isolation of music practice rooms with the signal processing of an active acoustic system (with time variant-gain before feedback) musicians can now benefit from the experience of practicing in multiple acoustic environments. Musicians select from various acoustics environments from a typical small practice room to that of a large space such as a sports arena. The variability of the acoustic environment allows the musician to hear clearly their intonation and articulation, which may be difficult to discern in a small practice room. To effectively communicate the various acoustics environments, the musicians must be immersed in the sound field of the active acoustics without being able to discern source locations of the speakers. The system must also be able to support the dynamic range of the musicians without presenting artifacts of its own such as system noise or audible distortion. This paper deals with the design constraints needed to meet these requirements as well the antidotal responses from musicians who have used these environments for practice.

  16. An active acoustic tripwire for simultaneous detection and localization of multiple underwater intruders.

    PubMed

    Folegot, Thomas; Martinelli, Giovanna; Guerrini, Piero; Stevenson, J Mark

    2008-11-01

    An algorithm allowing simultaneous detection and localization of multiple submerged targets crossing an acoustic tripwire based on forward scattering is described and then evaluated based upon data collected at sea. This paper quantifies the agreement between the theoretical performance and the results obtained from processing data gathered at sea for crossings at several depths and ranges. Targets crossing the acoustic field produce shadows on each side of the barrier, for specific sensors and for specific acoustic paths. In post-processing, a model is invoked to associate expected paths with the observed shadows. This process allows triangulation of the target's position inside the acoustic field. Precise localization is achieved by taking advantage of the multipath propagation structure of the received signal, together with the diversity of the source and receiver locations. Environmental robustness is demonstrated using simulations and can be explained by the use of an array of sources spatially distributed through the water column. PMID:19045773

  17. [Determination of a Spectrum of Lytic Activity of Bacteriophages by the Method of Acoustic Analysis].

    PubMed

    Guliy, O I; Zaitsev, B D; Kuznetsova, I E; Shikhabudinov, A M; Dykman, L A; Staroverov, S A; Karavaeva, O A; Pavliy, S A; Ignatov, O V

    2015-01-01

    The changes in the electro-acoustic parameters of cell suspension due to the interaction of cells with bacteriophages both in a pure. culture and in the presence of extraneous microflora were investigated. It has been found that the specific changes in the electroacoustic parameters of cell suspension under the action of bacteriophage occur only in microbial cells which are sensitive to the bacteriophage studied. It has been established that a sensor unit allows of distinguishing a situation when the bacterial cells are infected with specific bacteriophages of the control experiments and a situation with no introduction of infection. An approximate criterion of the presence of specific interactions of bacteriophages and cells in suspension was developed. In accordance with this criterion the change in electrical impedance of the sensor unit must not be less than - 1%. In control experiments a standard microbiological technique, plating the cells infected with bacteriophages on solid nutrient medium, was used. For the first time the possibility of using the method of electroacoustic analysis for determination of a spectrum of lytic activity of bacteriophages was shown. The results obtained may be used for development of a new express method for determining the sensitivity to bacteriophages of the microbial cells. PMID:26394472

  18. Acoustically active liposome-nanobubble complexes for enhanced ultrasonic imaging and ultrasound-triggered drug delivery.

    PubMed

    Nguyen, An T; Wrenn, Steven P

    2014-01-01

    Ultrasound is well known as a safe, reliable imaging modality. A historical limitation of ultrasound, however, was its inability to resolve structures at length scales less than nominally 20 µm, which meant that classical ultrasound could not be used in applications such as echocardiography and angiogenesis where one requires the ability to image small blood vessels. The advent of ultrasound contrast agents, or microbubbles, removed this limitation and ushered in a new wave of enhanced ultrasound applications. In recent years, the microbubbles have been designed to achieve yet another application, namely ultrasound-triggered drug delivery. Ultrasound contrast agents are thus tantamount to 'theranostic' vehicles, meaning they can do both therapy (drug delivery) and imaging (diagnostics). The use of ultrasound contrast agents as drug delivery vehicles, however, is perhaps less than ideal when compared to traditional drug delivery vehicles (e.g., polymeric microcapsules and liposomes) which have greater drug carrying capacities. The drawback of the traditional drug delivery vehicles is that they are not naturally acoustically active and cannot be used for imaging. The notion of a theranostic vehicle is sufficiently intriguing that many attempts have been made in recent years to achieve a vehicle that combines the echogenicity of microbubbles with the drug carrying capacity of liposomes. The attempts can be classified into three categories, namely entrapping, tethering, and nesting. Of these, nesting is the newest-and perhaps the most promising. PMID:24459007

  19. PREFACE: ARENA 2006—Acoustic and Radio EeV Neutrino detection Activities

    NASA Astrophysics Data System (ADS)

    Thompson, Lee

    2007-06-01

    The International Conference on Acoustic and Radio EeV Neutrino Activities, ARENA 2006 was jointly hosted by the Universities of Northumbria and Sheffield at the City of Newcastle Campus of the University of Northumbria in June 2006. ARENA 2006 was the latest in a series of meetings which have addressed, either separately or jointly, the use of radio and acoustic sensors for the detection of highly relativistic particles. Previous successful meetings have taken place in Los Angeles (RADHEP, 2000), Stanford (2003) and DESY Zeuthen (ARENA 2005). A total of 50 scientists from across Europe, the US and Japan attended the conference presenting status reports and results from a number of projects and initiatives spread as far afield as the Sweden and the South Pole. The talks presented at the meeting and the proceedings contained herein represent a `snapshot' of the status of the fields of acoustic and radio detection at the time of the conference. The three day meeting also included two invited talks by Dr Paula Chadwick and Dr Johannes Knapp who gave excellent summaries of the related astroparticle physics fields of high energy gamma ray detection and high energy cosmic ray detection respectively. As well as a full academic agenda there were social events including a Medieval themed conference banquet at Lumley Castle and a civic reception kindly provided by the Lord Mayor of Newcastle and hosted at the Mansion House. Thanks must go to the International Advisory Board members for their input and guidance, the Local Organising Committee for their hard work in bringing everything together and finally the delegates for the stimulating, enthusiastic and enjoyable spirit in which ARENA 2006 took place. Lee Thompson

    International Advisory Board

    G. Anton, ErlangenD. Besson, Kansas
    J. Blümer, KarlsruheA. Capone, Rome
    H. Falcke, BonnP. Gorham, Hawaii
    G. Gratta

  20. Comparison of acoustic performance of five muffler configurations on a small helicopter. [acoustic properties of modified helicopter exhaust system

    NASA Technical Reports Server (NTRS)

    Pegg, R. J.; Hilton, D. A.

    1974-01-01

    A field noise measurement program has been conducted on a standard Bell 47 series helicopter and on one that had been modified with specially designed, airframe-mounted mufflers to reduce the engine exhaust noise. The purpose of the study was to evaluate the acoustic performance of five experimental exhaust muffler configurations for a helicopter reciprocating engine in an operational environment. All muffler configurations produced beneficial engine exhaust noise reductions but some configurations were markedly better than others. Flyover noise results indicated that maximum overall noise reductions of approximately 8 db were obtained with the various mufflers. The rotor noise was judged to be the dominant noise component for the muffler-equipped helicopters whereas the engine noise was the dominant component for the basic configuration.

    1. Design guidelines for avoiding thermo-acoustic oscillations in helium piping systems

      SciTech Connect

      Gupta, Prabhat Kumar; Rabehl, Roger

      2015-04-02

      Thermo-acoustic oscillations are a commonly observed phenomenon in helium cryogenic systems, especially in tubes connecting hot and cold areas. The open ends of these tubes are connected to the lower temperature (typically at 4.5 K), and the closed ends of these tubes are connected to the high temperature (300 K). Cryogenic instrumentation installations provide ideal conditions for these oscillations to occur due to the steep temperature gradient along the tubing. These oscillations create errors in measurements as well as an undesirable heat load to the system. The work presented here develops engineering guidelines to design oscillation-free helium piping. This work also studies the effect of different piping inserts and shows how the proper geometrical combinations have to be chosen to avoid thermo-acoustic oscillations. The effect of an 80 K intercept is also studied and shows that thermo-oscillations can be dampened by placing the intercept at an appropriate location. As a result, the design of helium piping based on the present work is also verified with the experimental results available in open literature.

    2. Vibro-acoustic characterization of flexible hose in CO2 car air conditioning systems

      NASA Astrophysics Data System (ADS)

      Angelini, F.; Bergami, A.; Martarelli, M.; Tomasini, E. P.

      2008-06-01

      Following the EU directive 2006/40/EC proscribing from 2011 that refrigerant fluids must have a global warming potential not higher than 150, it will not be allowed anymore to employ the current R134a on car air conditioning systems. Maflow s.p.a (automotive hose maker) is developing products for each possible new refrigerant. This paper is focused on hoses for CO2 refrigerants operating in the worst conditions because of the high pressures and temperatures at which they are working (with R134a the high pressure is 18 bar and low pressure is 3 bar; with CO2 the high pressure is 100 bar and low pressure is 35 bar). Therefore the noise emission control of the CO2 air conditioning systems is very important. The aim of this study is to develop a standard measurement method for the vibro - acoustic characterization of High Pressure (HP - Shark F4) and Low Pressure (LP - ULEV) hoses to reduce noise emission and raise car passenger comfort; in particular deep research on high pressure hose. The method is based on the measurement of the vibration level of the hoses in a standard test bench by means of a Laser Doppler Vibrometer (LDV) and its acoustic emission by a sound intensity probe.

    3. Design guidelines for avoiding thermo-acoustic oscillations in helium piping systems

      DOE PAGESBeta

      Gupta, Prabhat Kumar; Rabehl, Roger

      2015-04-02

      Thermo-acoustic oscillations are a commonly observed phenomenon in helium cryogenic systems, especially in tubes connecting hot and cold areas. The open ends of these tubes are connected to the lower temperature (typically at 4.5 K), and the closed ends of these tubes are connected to the high temperature (300 K). Cryogenic instrumentation installations provide ideal conditions for these oscillations to occur due to the steep temperature gradient along the tubing. These oscillations create errors in measurements as well as an undesirable heat load to the system. The work presented here develops engineering guidelines to design oscillation-free helium piping. This workmore » also studies the effect of different piping inserts and shows how the proper geometrical combinations have to be chosen to avoid thermo-acoustic oscillations. The effect of an 80 K intercept is also studied and shows that thermo-oscillations can be dampened by placing the intercept at an appropriate location. As a result, the design of helium piping based on the present work is also verified with the experimental results available in open literature.« less

    4. Uniform mixing in paper-based microfluidic systems using surface acoustic waves.

      PubMed

      Rezk, Amgad R; Qi, Aisha; Friend, James R; Li, Wai Ho; Yeo, Leslie Y

      2012-02-21

      Paper-based microfluidics has recently received considerable interest due to their ease and low cost, making them extremely attractive as point-of-care diagnostic devices. The incorporation of basic fluid actuation and manipulation schemes on paper substrates, however, afford the possibility to extend the functionality of this simple technology to a much wider range of typical lab-on-a-chip operations, given its considerable advantages in terms of cost, size and integrability over conventional microfluidic substrates. We present a convective actuation mechanism in a simple paper-based microfluidic device using surface acoustic waves to drive mixing. Employing a Y-channel structure patterned onto paper, the mixing induced by the 30 MHz acoustic waves is shown to be consistent and rapid, overcoming several limitations associated with its capillary-driven passive mixing counterpart wherein irreproducibilities and nonuniformities are often encountered in the mixing along the channel--capillary-driven passive mixing offers only poor control, is strongly dependent on the paper's texture and fibre alignment, and permits backflow, all due to the scale of the fibres being significant in comparison to the length scales of the features in a microfluidic system. Using a novel hue-based colourimetric technique, the mixing speed and efficiency is compared between the two methods, and used to assess the effects of changing the input power, channel tortuousity and fibre/flow alignment for the acoustically-driven mixing. The hue-based technique offers several advantages over grayscale pixel intensity analysis techniques in facilitating quantification without limitations on the colour contrast of the samples, and can be used, for example, for quantification in on-chip immunochromatographic assays. PMID:22193520

    5. European Neutron Activation System.

      2013-01-11

      Version 03 EASY-2010 (European Activation System) consists of a wide range of codes, data and documentation all aimed at satisfying the objective of calculating the response of materials irradiated in a neutron flux. The main difference from the previous version is the upper energy limit, which has increased from 20 to 60 MeV. It is designed to investigate both fusion devices and accelerator based materials test facilities that will act as intense sources of high-energymore » neutrons causing significant activation of the surrounding materials. The very general nature of the calculational method and the data libraries means that it is applicable (with some reservations) to all situations (e.g. fission reactors or neutron sources) where materials are exposed to neutrons below 60 MeV. EASY can be divided into two parts: data and code development tools and user tools and data. The former are required to develop the latter, but EASY users only need to be able to use the inventory code FISPACT and be aware of the contents of the EAF library (the data source). The complete EASY package contains the FISPACT-2007 inventory code, the EAF-2003, EAF-2005, EAF-2007 and EAF-2010 libraries, and the EASY User Interface for the Window version. The activation package EASY-2010 is the result of significant development to extend the upper energy range from 20 to 60 MeV so that it is capable of being used for IFMIF calculations. The EAF-2010 library contains 66,256 reactions, almost five times more than in EAF-2003 (12,617). Deuteron-induced and proton-induced cross section libraries are also included, and can be used with EASY to enable calculations of the activation due to deuterons and proton [2].« less

    6. PC-based real-time acoustic source locator and sound capture system for teleconferencing

      NASA Astrophysics Data System (ADS)

      Morde, Ashutosh; Grove, Deborah; Utama, Robert

      2002-05-01

      A PC-based real time acoustic source locator and sound capture system has been developed. The system is implemented using Frontier Design A/D converters and the Intel Signal Processing Library directly on a 1 GHz Pentium III machine, without a DSP board. The source locator uses the cross-power spectral phase to locate a moving talker. The algorithm also uses an energy detector that minimizes incorrect location estimates by neglecting frames with high background noise. The source locator provides 8 location estimates per second. A 16-element 0.90 m linear delay-sum beamformer has also been implemented in the system as a method for selective sound capture. The ability of the source locator to detect talkers in a typical office environment is evaluated. In addition, the array response is measured. [Work supported by Intel.

    7. An Acoustic OFDM System with Symbol-by-Symbol Doppler Compensation for Underwater Communication.

      PubMed

      MinhHai, Tran; Rie, Saotome; Suzuki, Taisaku; Wada, Tomohisa

      2016-01-01

      We propose an acoustic OFDM system for underwater communication, specifically for vertical link communications such as between a robot in the sea bottom and a mother ship in the surface. The main contributions are (1) estimation of time varying Doppler shift using continual pilots in conjunction with monitoring the drift of Power Delay Profile and (2) symbol-by-symbol Doppler compensation in frequency domain by an ICI matrix representing nonuniform Doppler. In addition, we compare our proposal against a resampling method. Simulation and experimental results confirm that our system outperforms the resampling method when the velocity changes roughly over OFDM symbols. Overall, experimental results taken in Shizuoka, Japan, show our system using 16QAM, and 64QAM achieved a data throughput of 7.5 Kbit/sec with a transmitter moving at maximum 2 m/s, in a complicated trajectory, over 30 m vertically. PMID:27057558

    8. An Acoustic OFDM System with Symbol-by-Symbol Doppler Compensation for Underwater Communication

      PubMed Central

      MinhHai, Tran; Rie, Saotome; Suzuki, Taisaku; Wada, Tomohisa

      2016-01-01

      We propose an acoustic OFDM system for underwater communication, specifically for vertical link communications such as between a robot in the sea bottom and a mother ship in the surface. The main contributions are (1) estimation of time varying Doppler shift using continual pilots in conjunction with monitoring the drift of Power Delay Profile and (2) symbol-by-symbol Doppler compensation in frequency domain by an ICI matrix representing nonuniform Doppler. In addition, we compare our proposal against a resampling method. Simulation and experimental results confirm that our system outperforms the resampling method when the velocity changes roughly over OFDM symbols. Overall, experimental results taken in Shizuoka, Japan, show our system using 16QAM, and 64QAM achieved a data throughput of 7.5 Kbit/sec with a transmitter moving at maximum 2 m/s, in a complicated trajectory, over 30 m vertically. PMID:27057558

    9. Medical Acoustics

      NASA Astrophysics Data System (ADS)

      Beach, Kirk; Dunmire, Barbrina

      Medical acoustics can be subdivided into diagnostics and therapy. Diagnostics are further separated into auditory and ultrasonic methods, and both employ low amplitudes. Therapy (excluding medical advice) uses ultrasound for heating, cooking, permeablizing, activating and fracturing tissues and structures within the body, usually at much higher amplitudes than in diagnostics. Because ultrasound is a wave, linear wave physics are generally applicable, but recently nonlinear effects have become more important, even in low-intensity diagnostic applications.

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

      NASA Astrophysics Data System (ADS)

      Summers, Jason Erik

      A frequency-dependent model for levels and decay rates of reverberant energy in systems of coupled rooms is developed and compared with measurements conducted in a 1:10 scale model and in Bass Hall, Fort Worth, TX. Schroeder frequencies of subrooms, fSch, characteristic size of coupling apertures, a, relative to wavelength lambda, and characteristic size of room surfaces, l, relative to lambda define the frequency regions. At high frequencies [HF (f >> f Sch, a >> lambda, l >> lambda)], this work improves upon prior statistical-acoustics (SA) coupled-ODE models by incorporating geometrical-acoustics (GA) corrections for the model of decay within subrooms and the model of energy transfer between subrooms. Previous researchers developed prediction algorithms based on computational GA. Comparisons of predictions derived from beam-axis tracing with scale-model measurements indicate that systematic errors for coupled rooms result from earlier tail-correction procedures that assume constant quadratic growth of reflection density. A new algorithm is developed that uses ray tracing rather than tail correction in the late part and is shown to correct this error. At midfrequencies [MF (f >> f Sch, a ˜ lambda)], HF models are modified to account for wave effects at coupling apertures by including analytically or heuristically derived power transmission coefficients tau. This work improves upon prior SA models of this type by developing more accurate estimates of random-incidence tau. While the accuracy of the MF models is difficult to verify, scale-model measurements evidence the expected behavior. The Biot-Tolstoy-Medwin-Svensson (BTMS) time-domain edge-diffraction model is newly adapted to study transmission through apertures. Multiple-order BTMS scattering is theoretically and experimentally shown to be inaccurate due to the neglect of slope diffraction. At low frequencies (f ˜ f Sch), scale-model measurements have been qualitatively explained by application of

    11. Parallel direct numerical simulation of wake vortex detection using monostatic and bistatic radio acoustic sounding systems

      NASA Astrophysics Data System (ADS)

      Boluriaan Esfahaani, Said

      A parallel two-dimensional code is developed in this thesis to numerically simulate wake vortex detection using a Radio Acoustic Sounding System (RASS). The Maxwell equations for media with non-uniform permittivity and the linearized Euler equations for media with non-uniform mean flow are the main framework for the simulations. The code is written in Fortran 90 with the Message Passing Interface (MPI) for parallel implementation. The main difficulty encountered with a time accurate simulation of a RASS is the number of samples required to resolve the Doppler shift in the scattered electromagnetic signal. Even for a 1D simulation with a typical scatterer size, the CPU time required to run the code is far beyond currently available computer resources. Two solutions that overcome this problem are described. In the first the actual electromagnetic wave propagation speed is replaced with a much lower value. This allows an explicit, time accurate numerical scheme to be used. In the second the governing differential equations are recast in order to remove the carrier frequency and solve only for the frequency shift using an implicit scheme with large time steps. The numerical stability characteristics of the resulting discretized equation with complex coefficients are examined. A number of cases for both the monostatic and bistatic configurations are considered. First, a uniform mean flow is considered and the RASS simulation is performed for two different types of incident acoustic field, namely a short single frequency acoustic pulse and a continuous broadband acoustic source. Both the explicit and implicit schemes are examined and the mean flow velocity is determined from the spectrum of the backscattered electromagnetic signal with very good accuracy. Second, the Taylor and Oseen vortex models are considered and their velocity field along the incident electromagnetic beam is retrieved. The Abel transform is then applied to the velocity profiles determined by both

    12. Active Travel-Time Tomography using a Distributed Acoustic Sensing Array

      NASA Astrophysics Data System (ADS)

      Lancelle, C.; Fratta, D.; Lord, N. E.; Wang, H. F.; Chalari, A.

      2015-12-01

      Distributed acoustic sensing (DAS) is a sensor array used for monitoring ground motion by utilizing the interaction of light pulses with sections of a fiber-optic cable. In September 2013 a field test was conducted at the NEES@UCSB Garner Valley field site in Southern California incorporating DAS technology. A 762-meter-long fiber-optic cable was trenched to a depth of about 0.3 m in a rectangular design with two interior diagonal segments. The fiber was excited by a number of sources, including a 45 kN shear shaker and a smaller 450 N portable mass shaker, both of which were available through NEES@UCLA. In addition to these sources, signals were recorded from a minivib source and hammer blows on a steel plate, as well as 8 hours of overnight ambient noise recording. One goal of the field test was to evaluate the use of DAS for tomographic studies. The large number of measurement points inherent to DAS lends itself well to this type of study. Tomograms were constructed using two of the active-sources at multiple locations. There were 8 minivib locations within the array and 13 hammer locations along the boundary of the array. Travel-time data were collected with the DAS array. Two-dimensional velocity tomograms were constructed for different resolutions from the two active sources and compared. In all the images, the lowest velocities lie near the center of the array with higher velocities surrounding this area. The impact results, however, may contain an artifact due to multiple propagation modes. This research is part of the DOE's PoroTomo project.

    13. Synthesis, Acoustic Stability, and Pharmacologic Activities of Papaverine-Loaded Echogenic Liposomes for Ultrasound Controlled Drug Delivery

      PubMed Central

      KEE, PATRICK H.; ABRUZZO, TODD A.; SMITH, DENISE A.B.; KOPECHEK, JONATHAN A.; WANG, BOYU; HUANG, SHAOLING L.; MacDONALD, ROBERT C.; HOLLAND, CHRISTY K.; McPHERSON, DAVID D.

      2010-01-01

      Background development of encapsulated therapeutics that could be released upon ultrasound exposure has strong implications for enhancing drug effects at the target site. We have developed echogenic liposomes (ELIP) suitable for ultrasound imaging of blood flow and ultrasound-mediated intravascular drug release. Papaverine was chosen as the test drug because its clinical application requires high concentration in the target vascular bed but low concentration in the systemic circulation. Methods the procedure for preparation of standard ELIP was modified by including Papaverine hydrochloride in the lipid hydration solution, followed by three freeze-thaw cycles to increase encapsulation of the drug. Sizing and encapsulation pharmacokinetics were performed using a Coulter counter and a phosphodiesterase activity assay. Stability of Papaverine-loaded ELIP (PELIP) was monitored with a clinical diagnostic ultrasound scanner equipped with a linear array transducer at a center frequency of 4.5 MHz by assessing the mean digital intensity within a region of interest over time. The stability of PELIP was compared to those of standard ELIP and Optison™. Results relative to standard ELIP, PELIP were larger (median diameter = 1.88 ± 0.10 μm for PELIP vs 1.08 ± 0.15 μm for ELIP) and had lower MGSV (92 ± 24.8 for PELIP compared to 142.3 ± 10.7 for ELIP at lipid concentrations of 50 μg/ml). The maximum loading efficiency and mean encapsulated concentration were 24% ± 7% and 2.1 ± 0.7 mg/ml, respectively. Papaverine retained its phosphodiesterase inhibitory activity when associated with PELIP. Furthermore, a fraction of this activity remained latent until released by dissolution of liposomal membranes with detergent. The stability of both PELIP and standard ELIP were similar, but both are greater than that of Optison™. Conclusions our results suggest that PELIP have desirable physical, biochemical, biological, and acoustic characteristics for potential in vivo

    14. Image formation and system analysis of a scanning tomographic acoustic microscope

      NASA Astrophysics Data System (ADS)

      Kent, Samuel Davis, III

      This dissertation focuses on research that has been conducted to implement an automated Scanning Tomographic Acoustic Microscope (STAM), and research that has been performed to increase the understanding of the performance characteristics of the STAM. STAM technology permits high resolution microscopy which yields important information on the internal structure and acoustic properties of thick specimens, provided that technology is utilized in a cohesive manner. Prior to the research conducted for this dissertation, only a proof-of-concept STAM had been developed; actual STAM imaging was difficult and impractical. This dissertation describes the hardware and software development that has led to the first automated STAM. It focuses on significant problems that were encountered and their solutions. Specifically, accurate data acquisition necessitated the development of special-purpose data acquisition hardware, rotational controls, frequency controls, and automation controls. Inaccuracies in the laser scanning hardware were identified as a significant source of reconstruction error. This error was removed by estimation and correction algorithms. Rotation of the specimen for multiple-angle tomography required the development of a noise-tolerant projection-pose estimation algorithm. An iterative technique for image enhancement is also presented. The resulting STAM system is evaluated to determine its performance characteristics. A component-wise resolution analysis is presented that specifies the resolution-limit in both range and cross-range. The dependency of reconstruction quality on accurate representation of the magnitude and phase of the detected wave fields is also provided.

    15. Acoustic system for the estimation of the temporary blood chamber volume of the POLVAD heart supporting prosthesis

      PubMed Central

      2012-01-01

      Background The paper presents a newly researched acoustic system for blood volume measurements for the developed family of Polish ventricular assist devices. The pneumatic heart-supporting devices are still the preferred solution in some cases, and monitoring of their operation, especially the temporary blood volume, is yet to be solved. Methods The prototype of the POLVAD-EXT prosthesis developed by the Foundation of Cardiac Surgery Development, Zabrze, Poland, is equipped with the newly researched acoustic blood volume measurement system based on the principle of Helmholtz’s acoustic resonance. The results of static volume measurements acquired using the acoustic sensor were verified by measuring the volume of the liquid filling the prosthesis. Dynamic measurements were conducted on the hybrid model of the human cardiovascular system at the Foundation, with the Transonic T410 (11PLX transducer - 5% uncertainty) ultrasound flow rate sensor, used as the reference. Results The statistical analysis of a series of static tests have proved that the sensor solution provides blood volume measurement results with uncertainties (understood as a standard mean deviation) of less than 10%. Dynamic tests show a high correlation between the results of the acoustic system and those obtained by flow rate measurements using an ultrasound transit time type sensor. Conclusions The results show that noninvasive, online temporary blood volume measurements in the POLVAD-EXT prosthesis, making use of the newly developed acoustic system, provides accurate static and dynamic measurements results. Conducted research provides the preliminary view on the possibility of reducing the additional sensor chamber volume in future. PMID:22998766

    16. Assisting the Visually Impaired: Obstacle Detection and Warning System by Acoustic Feedback

      PubMed Central

      Rodríguez, Alberto; Yebes, J. Javier; Alcantarilla, Pablo F.; Bergasa, Luis M.; Almazán, Javier; Cela, Andrés

      2012-01-01

      The aim of this article is focused on the design of an obstacle detection system for assisting visually impaired people. A dense disparity map is computed from the images of a stereo camera carried by the user. By using the dense disparity map, potential obstacles can be detected in 3D in indoor and outdoor scenarios. A ground plane estimation algorithm based on RANSAC plus filtering techniques allows the robust detection of the ground in every frame. A polar grid representation is proposed to account for the potential obstacles in the scene. The design is completed with acoustic feedback to assist visually impaired users while approaching obstacles. Beep sounds with different frequencies and repetitions inform the user about the presence of obstacles. Audio bone conducting technology is employed to play these sounds without interrupting the visually impaired user from hearing other important sounds from its local environment. A user study participated by four visually impaired volunteers supports the proposed system. PMID:23247413

    17. Ion-acoustic compressive and rarefactive solitons in an electron-beam plasma system

      SciTech Connect

      Yadav, L.L.; Tiwari, R.S.; Sharma, S.R. )

      1994-03-01

      Using the general formulation of reductive perturbation method, the Korteweg--de Vries (KdV) equation is derived for an electron-beam plasma with hot isothermal beam and plasma electrons and warm ions. The soliton solution of the KdV equation is discussed in detail. It is found that above a critical velocity of electron-beam two additional ion-acoustic soliton branches appear. It is found that corresponding to two linear modes, the system supports the existence of compressive as well as rarefactive solitons depending upon the plasma parameters, while corresponding to other two wave modes, the system supports only rarefactive solitons. The effect of different parameters on the characteristics of solitons have been investigated in detail.

    18. Measurement of the acoustic-to-optical phonon coupling in multicomponent systems

      NASA Astrophysics Data System (ADS)

      Caretta, Antonio; Donker, Michiel C.; Perdok, Diederik W.; Abbaszadeh, Davood; Polyakov, Alexey O.; Havenith, Remco W. A.; Palstra, Thomas T. M.; van Loosdrecht, Paul H. M.

      2015-02-01

      In this paper we investigate the acoustic-to-optical up-conversion phonon processes in a multicomponent system. These processes take place during heat transport and limit the efficiency of heat flow. By combining time-resolved optical and heat capacity experiments we quantify the thermal coupling constant to be g ˜0.4 1017 W/Km3 . The method is based on selective excitation of a part of a multicomponent system, and the measurement of the thermalization dynamics by probing the linear birefringence of the sample with femtosecond resolution. In particular, we study a layered multiferroic organic-inorganic hybrid, in the vicinity of the ferroelectric phase transition. A diverging term of the heat capacity is associated to soft-mode dynamics, in agreement with previous spectroscopy measurements.

    19. Thermal-Acoustic Analysis of a Metallic Integrated Thermal Protection System Structure

      NASA Technical Reports Server (NTRS)

      Behnke, Marlana N.; Sharma, Anurag; Przekop, Adam; Rizzi, Stephen A.

      2010-01-01

      A study is undertaken to investigate the response of a representative integrated thermal protection system structure under combined thermal, aerodynamic pressure, and acoustic loadings. A two-step procedure is offered and consists of a heat transfer analysis followed by a nonlinear dynamic analysis under a combined loading environment. Both analyses are carried out in physical degrees-of-freedom using implicit and explicit solution techniques available in the Abaqus commercial finite-element code. The initial study is conducted on a reduced-size structure to keep the computational effort contained while validating the procedure and exploring the effects of individual loadings. An analysis of a full size integrated thermal protection system structure, which is of ultimate interest, is subsequently presented. The procedure is demonstrated to be a viable approach for analysis of spacecraft and hypersonic vehicle structures under a typical mission cycle with combined loadings characterized by largely different time-scales.

    20. The acoustic simulation and analysis of complicated reciprocating compressor piping systems, II: Program structure and applications

      NASA Astrophysics Data System (ADS)

      To, C. W. S.

      1984-09-01

      The main objectives of the investigation reported in this paper, Part II, and its companion paper, Part I, are (a) to provide a formulation, including the mean flow effects and suitable for digital computer automation, of the acoustics of complicated piping systems, and (b) to develop a comprehensive digital computer program for the simulation and analysis of complicated reciprocating compressor piping systems. In this paper, the digital computer program structure and applications of the program developed, written in Fortran IV, are described. It is concluded that the computer program is versatile and user-friendly. It is capable of providing a great deal of information from one set of input data, and is open-ended and modular for updating.

    1. Vibro-acoustic propagation of gear dynamics in a gear-bearing-housing system

      NASA Astrophysics Data System (ADS)

      Guo, Yi; Eritenel, Tugan; Ericson, Tristan M.; Parker, Robert G.

      2014-10-01

      This work developed a computational process to predict noise radiation from gearboxes. It developed a system-level vibro-acoustic model of an actual gearbox, including gears, bearings, shafts, and housing structure, and compared the results to experiments. The meshing action of gear teeth causes vibrations to propagate through shafts and bearings to the housing radiating noise. The vibration excitation from the gear mesh and the system response were predicted using finite element and lumped-parameter models. From these results, the radiated noise was calculated using a boundary element model of the housing. Experimental vibration and noise measurements from the gearbox confirmed the computational predictions. The developed tool was used to investigate the influence of standard rolling element and modified journal bearings on gearbox radiated noise.

    2. Acoustic chaos

      SciTech Connect

      Lauterborn, W.; Parlitz, U.; Holzfuss, J.; Billo, A.; Akhatov, I.

      1996-06-01

      Acoustic cavitation, a complex, spatio-temporal dynamical system, is investigated with respect to its chaotic properties. The sound output, the {open_quote}{open_quote}noise{close_quote}{close_quote}, is subjected to time series analysis. The spatial dynamics of the bubble filaments is captured by high speed holographic cinematography and subsequent digital picture processing from the holograms. Theoretical models are put forward for describing the pattern formation. {copyright} {ital 1996 American Institute of Physics.}

    3. International Space Station Acoustics - A Status Report

      NASA Technical Reports Server (NTRS)

      Allen, Christopher S.; Denham, Samuel A.

      2011-01-01

      It is important to control acoustic noise aboard the International Space Station (ISS) to provide a satisfactory environment for voice communications, crew productivity, and restful sleep, and to minimize the risk for temporary and permanent hearing loss. Acoustic monitoring is an important part of the noise control process on ISS, providing critical data for trend analysis, noise exposure analysis, validation of acoustic analysis and predictions, and to provide strong evidence for ensuring crew health and safety, thus allowing Flight Certification. To this purpose, sound level meter (SLM) measurements and acoustic noise dosimetry are routinely performed. And since the primary noise sources on ISS include the environmental control and life support system (fans and airflow) and active thermal control system (pumps and water flow), acoustic monitoring will indicate changes in hardware noise emissions that may indicate system degradation or performance issues. This paper provides the current acoustic levels in the ISS modules and sleep stations, and is an update to the status presented in 20031. Many new modules, and sleep stations have been added to the ISS since that time. In addition, noise mitigation efforts have reduced noise levels in some areas. As a result, the acoustic levels on the ISS have improved.

    4. International Space Station Acoustics - A Status Report

      NASA Technical Reports Server (NTRS)

      Allen, Christopher S.

      2015-01-01

      It is important to control acoustic noise aboard the International Space Station (ISS) to provide a satisfactory environment for voice communications, crew productivity, alarm audibility, and restful sleep, and to minimize the risk for temporary and permanent hearing loss. Acoustic monitoring is an important part of the noise control process on ISS, providing critical data for trend analysis, noise exposure analysis, validation of acoustic analyses and predictions, and to provide strong evidence for ensuring crew health and safety, thus allowing Flight Certification. To this purpose, sound level meter (SLM) measurements and acoustic noise dosimetry are routinely performed. And since the primary noise sources on ISS include the environmental control and life support system (fans and airflow) and active thermal control system (pumps and water flow), acoustic monitoring will reveal changes in hardware noise emissions that may indicate system degradation or performance issues. This paper provides the current acoustic levels in the ISS modules and sleep stations and is an update to the status presented in 2011. Since this last status report, many payloads (science experiment hardware) have been added and a significant number of quiet ventilation fans have replaced noisier fans in the Russian Segment. Also, noise mitigation efforts are planned to reduce the noise levels of the T2 treadmill and levels in Node 3, in general. As a result, the acoustic levels on the ISS continue to improve.

    5. Optoacoustic tweezers: a programmable, localized cell concentrator based on opto-thermally generated, acoustically activated, surface bubbles.

      PubMed

      Xie, Yuliang; Zhao, Chenglong; Zhao, Yanhui; Li, Sixing; Rufo, Joseph; Yang, Shikuan; Guo, Feng; Huang, Tony Jun

      2013-05-01

      We present a programmable, biocompatible technique for dynamically concentrating and patterning particles and cells in a microfluidic device. Since our technique utilizes opto-thermally generated, acoustically activated, surface bubbles, we name it "optoacoustic tweezers". The optoacoustic tweezers are capable of concentrating particles/cells at any prescribed locations in a microfluidic chamber without the use of permanent structures, rendering it particularly useful for the formation of flexible, complex cell patterns. Additionally, this technique has demonstrated excellent biocompatibility and can be conveniently integrated with other microfluidic units. In our experiments, micro-bubbles were generated by focusing a 405 nm diode laser onto a gold-coated glass chamber. By properly tuning the laser, we demonstrate precise control over the position and size of the generated bubbles. Acoustic waves were then applied to activate the surface bubbles, causing them to oscillate at an optimized frequency. The resulting acoustic radiation force allowed us to locally trap particles/cells, including 15 μm polystyrene beads and HeLa cells, around each bubble. Cell-adhesion tests were also conducted after cell concentrating to confirm the biocompatibility of this technique. PMID:23511348

    6. Comparison of Active Noise Control Structures in the Presence of Acoustical Feedback by Using THEH∞SYNTHESIS Technique

      NASA Astrophysics Data System (ADS)

      Bai, M. R.; Lin, H. H.

      1997-10-01

      This study compares three control structures of active noise cancellation for ducts: feedback control, feedforward control, and hybrid control. These structures are compared in terms of performance, stability, and robustness by using a general framework of theH∞robust control theory. In addition, theH∞synthesis procedure automatically incorporates the acoustic feedback path that is usually a plaguing problem to feedforward control design. The controllers are implemented by using a digital signal processor and tested on a finite-length duct. In an experimental verification, the proposed controllers are also compared with the well-known filtered-uleast mean square (FULMS) controller. The advantages and disadvantages of each ANC structure as well as the adverse effects due to acoustic feedback are addressed.

    7. AST Launch Vehicle Acoustics

      NASA Technical Reports Server (NTRS)

      Houston, Janice; Counter, D.; Giacomoni, D.

      2015-01-01

      The liftoff phase induces acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are then used in the prediction of internal vibration responses of the vehicle and components which result in the qualification levels. Thus, predicting these liftoff acoustic (LOA) environments is critical to the design requirements of any launch vehicle. If there is a significant amount of uncertainty in the predictions or if acoustic mitigation options must be implemented, a subscale acoustic test is a feasible pre-launch test option to verify the LOA environments. The NASA Space Launch System (SLS) program initiated the Scale Model Acoustic Test (SMAT) to verify the predicted SLS LOA environments and to determine the acoustic reduction with an above deck water sound suppression system. The SMAT was conducted at Marshall Space Flight Center and the test article included a 5% scale SLS vehicle model, tower and Mobile Launcher. Acoustic and pressure data were measured by approximately 250 instruments. The SMAT liftoff acoustic results are presented, findings are discussed and a comparison is shown to the Ares I Scale Model Acoustic Test (ASMAT) results.

    8. Breadboard sized photo-acoustic spectroscopy system using an FPGA based lock-in amplifier

      NASA Astrophysics Data System (ADS)

      Schill, John F.; Pellegrino, Paul M.; Holthoff, Ellen L.; Giza, Mark M.

      2015-05-01

      Over the past several years we have developed a photo-acoustic spectroscopic (PAS) technique for trace gas detection that is capable of parts per trillion (ppt) detection limits. The desire to reduce the size of the system has led to several efforts that have reduced the size of the various components of the system. We have reduced the dimensions of the resonant cell to micrometer scale (MEMS). We have worked with Daylight Solutions to reduce the size of the tunable quantum cascade laser (QCL) used in the system. In this paper we demonstrate the reduction in size of the entire system to a 12" x 12" footprint. We do this by implementing the lock-in amplifier on a field programmable gate array (FPGA) demonstration board that is also capable of acting as the system controller and data output device. We briefly describe the digital lock-in amplifier and sketch our implementation on the FPGA. We go on to compare the spectroscopic data we collected using this system with data we collected using a large rack mounted Stanford Research Systems SR830 lock-in amplifier and a PC.

    9. A debugging system for azimuthally acoustic logging tools based on modular and hierarchical design ideas

      NASA Astrophysics Data System (ADS)

      Zhang, K.; Ju, X. D.; Lu, J. Q.; Men, B. Y.

      2016-08-01

      On the basis of modular and hierarchical design ideas, this study presents a debugging system for an azimuthally sensitive acoustic bond tool (AABT). The debugging system includes three parts: a personal computer (PC), embedded front-end machine and function expansion boards. Modular and hierarchical design ideas are conducted in all design and debug processes. The PC communicates with the front-end machine via the Internet, and the front-end machine and function expansion boards connect each other by the extended parallel bus. In this method, the three parts of the debugging system form stable and high-speed data communication. This study not only introduces the system-level debugging and sub-system level debugging of the tool but also the debugging of the analogue signal processing board, which is important and greatly used in logging tools. Experiments illustrate that the debugging system can greatly improve AABT verification and calibration efficiency and that, board-level debugging can examine and improve analogue signal processing boards. The design thinking is clear and the design structure is reasonable, thus making it easy to extend and upgrade the debugging system.

    10. Passive Acoustic Detection of Wind Turbine In-Flow Conditions for Active Control and Optimization

      SciTech Connect

      Murray, Nathan E.

      2012-03-12

      Wind is a significant source of energy; however, the human capability to produce electrical energy still has many hurdles to overcome. One of these is the unpredictability of the winds in the atmospheric boundary layer (ABL). The ABL is highly turbulent in both stable and unstable conditions (based on the vertical temperature profile) and the resulting fluctuations can have a dramatic impact on wind turbine operation. Any method by which these fluctuations could be observed, estimated, or predicted could provide a benefit to the wind energy industry as a whole. Based on the fundamental coupling of velocity fluctuations to pressure fluctuations in the nearly incompressible flow in the ABL, This work hypothesizes that a ground-based array of infrasonic pressure transducers could be employed to estimate the vertical wind profile over a height relevant for wind turbines. To analyze this hypothesis, experiments and field deployments were conducted. Wind tunnel experiments were performed for a thick turbulent boundary layer over a neutral or heated surface. Surface pressure and velocity probe measurements were acquired simultaneously. Two field deployments yielded surface pressure data from a 49 element array. The second deployment at the Reese Technology Center in Lubbock, TX, also included data from a smaller aperture, 96-element array and a 200-meter tall meteorological tower. Analysis of the data successfully demonstrated the ability to estimate the vertical velocity profile using coherence data from the pressure array. Also, dynamical systems analysis methods were successful in identifying and tracking a gust type event. In addition to the passive acoustic profiling method, this program also investigated a rapid response Doppler SODAR system, the optimization of wind turbine blades for enhanced power with reduced aeroacoustic noise production, and the implementation of a wireless health monitoring system for the wind turbine blades. Each of these other objectives

    11. Field Trial of Distributed Acoustic Sensing Using Active Sources at Garner Valley, California

      NASA Astrophysics Data System (ADS)

      Wang, H. F.; Lord, N. E.; Chalari, A.; Lancelle, C.; Baldwin, J. A.; Castongia, E.; Fratta, D.; Nigbor, R. L.; Karaulanov, R.

      2014-12-01

      An optical fiber Distributed Acoustic Sensor array was deployed in a shallow trench at the site of the Garner Valley Downhole Array (GVDA) in southern California. The site was operated as a collaborator of the Network for Earthquake Engineering Simulation (NEES) by UCSB. The fiber-optic cable layout approximated a rectangle whose dimensions were roughly 160 meters by 80 meters. The layout included two subdiagonals to provide a variety of orientations of the cable relative to source locations. The study included different seismic sources deployed at a number of surveyed positions: a 45 kN shear shaker operated at the site by NEES@UCLA, a portable 450 N shaker, a small Vibroseis truck, and hammer blows on a steel plate to map cable locations. Several dozen separate tests were recorded in which each test typically included ten repeats. The data were utilized for several studies. First, the characteristics of the recorded signals were analyzed for directivity and sensitivity of the cable response (Lancelle et al., 2014, this meeting). The DAS system recorded dynamic ground events in the direction of the cable and hence comparisons with geophones required signal processing. The one-meter spacing of DAS traces could be well correlated over distances of a few meters. Second, swept-sine sources were used to obtain surface-wave velocity dispersion to determine near-surface shear-wave velocity distribution using Multispectral Analysis of Surface Waves (MASW) (Baldwin et al., 2014, this meeting). The results were in good agreement with previous Vibroseis results at the site (Stokoe et al. 2004). Third, a new method for time-frequency filtering was developed for extracting the surface-wave phase velocities from uncorrelated receiver traces (Lord et al., 2014, this meeting).

    12. Multi-system Acoustic Survey in Hecate Basin for Geohazard Assessment

      NASA Astrophysics Data System (ADS)

      Bloomer, S. F.; Rohr, K. M.; Chapman, N.; Beaudet, F.; Sutherland, G.

      2002-12-01

      In May and June of 2002, a geophysical survey was performed in southern Hecate Strait to assess sea floor and subsurface geohazards. The survey comprises a portion of a research program to study the impact of potential hydrocarbon exploration and production in Hecate Basin as part of the multidisciplinary NSERC/SSHRC funded Coast Under Stress project. Data were collected on 100 miles of survey lines over a grid consisting of 10 north-south lines crossed by 10 east-west lines with a line separation of 0.5 mile. Water depths were relatively uniform, ranging from 230-260 m over the area. 64-channel multichannel seismic data using a 120 cu in airgun source were collected for deep subsurface structural mapping. The shallow subsurface was imaged using the Huntec high-resolution seismic system with a boomer source. 50 KHz Simrad echosounder data suitable for seafloor classification were collected using Quester Tangent Corporation's QTC-V system. A standard geophysical seismic facies interpretation of the Huntec data suggested the shallow subsurface is composed of 3 units: (a) The lowest unit is composed of Tertiary siltstones/sandstones. This unit is highly folded/faulted, due to Miocene/Pliocene tectonism, and often is incised by paleochannels. (b) Overlying these sediments is a unit that has a relatively transparent acoustic facies. This unit likely represents Pleistocene glacial till. Its upper surface often outcrops at the seafloor, forming prominent moraine-like features at the seafloor. When overlain by the uppermost unit, it forms a strong reflector at that interface, though its continuity is often disrupted by gas that is present near that contact (c) The uppermost acoustic unit is relatively transparent and infills topographic lows and reaches a maximum thickness of 15 meters. It is likely composed of silts/sands. Seafloor classification of the echosounder data using feature extraction and cluster analysis indicates that this unit is somewhat acoustically

    13. High speed hybrid active system

      NASA Astrophysics Data System (ADS)

      Gonzalez, Ignacio F.; Chang, Fu-Kuo; Qing, Peter X.; Kumar, Amrita; Zhang, David

      2005-05-01

      A novel piezoelectric/fiber-optic system is developed for long-term health monitoring of aerospace vehicles and structures. The hybrid diagnostic system uses the piezoelectric actuators to input a controlled excitation to the structure and the fiber optic sensors to capture the corresponding structural response. The aim of the system is to detect changes in structures such as those found in aerospace applications (damage, cracks, aging, etc.). This system involves the use of fiber Bragg gratings, which may be either bonded to the surface of the material or embedded within it in order to detect the linear strain component produced by the excitation waves generate by an arbitrary waveform generator. Interrogation of the Bragg gratings is carried out using a high speed fiber grating demodulation unit and a high speed data acquisition card to provide actuation input. With data collection and information processing; is able to determine the condition of the structure. The demands on a system suitable for detecting ultrasonic acoustic waves are different than for the more common strain and temperature systems. On the one hand, the frequency is much higher, with typical values for ultrasonic frequencies used in non-destructive testing ranging from 100 kHz up to several MHz. On the other hand, the related strain levels are much lower, normally in the μstrain range. Fiber-optic solutions for this problem do exist and are particularly attractive for ultrasonic sensing as the sensors offer broadband detection capability.

    14. Technology Systems. Laboratory Activities.

      ERIC Educational Resources Information Center

      Brame, Ray; And Others

      This guide contains 43 modules of laboratory activities for technology education courses. Each module includes an instructor's resource sheet and the student laboratory activity. Instructor's resource sheets include some or all of the following elements: module number, course title, activity topic, estimated time, essential elements, objectives,…

    15. Deconvolution methods and systems for the mapping of acoustic sources from phased microphone arrays

      NASA Technical Reports Server (NTRS)

      Brooks, Thomas F. (Inventor); Humphreys, Jr., William M. (Inventor)

      2010-01-01

      A method and system for mapping acoustic sources determined from a phased microphone array. A plurality of microphones are arranged in an optimized grid pattern including a plurality of grid locations thereof. A linear configuration of N equations and N unknowns can be formed by accounting for a reciprocal influence of one or more beamforming characteristics thereof at varying grid locations among the plurality of grid locations. A full-rank equation derived from the linear configuration of N equations and N unknowns can then be iteratively determined. A full-rank can be attained by the solution requirement of the positivity constraint equivalent to the physical assumption of statically independent noise sources at each N location. An optimized noise source distribution is then generated over an identified aeroacoustic source region associated with the phased microphone array in order to compile an output presentation thereof, thereby removing the beamforming characteristics from the resulting output presentation.

    16. Research on ponderomotive driven Vlasov–Poisson system in electron acoustic wave parametric region

      SciTech Connect

      Xiao, C. Z.; Huang, T. W.; Liu, Z. J.; Zheng, C. Y.; He, X. T.; Qiao, B.

      2014-03-15

      Theoretical analysis and corresponding 1D Particle-in-Cell (PIC) simulations of ponderomotive driven Vlasov–Poisson system in electron acoustic wave (EAW) parametric region are demonstrated. Theoretical analysis identifies that under the resonant condition, a monochromatic EAW can be excited when the wave number of the drive ponderomotive force satisfies 0.26≲k{sub d}λ{sub D}≲0.53. If k{sub d}λ{sub D}≲0.26, nonlinear superposition of harmonic waves can be resonantly excited, called kinetic electrostatic electron nonlinear waves. Numerical simulations have demonstrated these wave excitation and evolution dynamics, in consistence with the theoretical predictions. The physical nature of these two waves is supposed to be interaction of harmonic waves, and their similar phase space properties are also discussed.

    17. The stability of freely-propagating ion acoustic waves in 2D systems

      NASA Astrophysics Data System (ADS)

      Chapman, Thomas; Berger, Richard; Banks, Jeffrey; Brunner, Stephan

      2014-10-01

      The stability of a freely-propagating ion acoustic wave (IAW) is a basic science problem that is made difficult by the need to resolve electron kinetic effects over a timescale that greatly exceeds the IAW period during numerical simulation. Recent results examining IAW stability using a 1D+1V Vlasov-Poisson solver indicate that instability is a fundamental property of IAWs that occurs over most if not all of the parameter space of relevance to ICF experiments. We present here new results addressing the fundamental question of IAW stability across a broad range of plasma conditions in a 2D+2V system using LOKI, ranging from a regime of relatively weak to a regime of relatively strong ion kinetic effects. Work performed under the auspices of the U.S. DOE by LLNL (DE-AC52-07NA27344) and funded by the LDRD Program at LLNL (12-ERD-061).

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

      NASA Astrophysics Data System (ADS)

      Shahab, S.; Erturk, A.

      2014-12-01

      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 dramatically

    19. Validation of an acoustic location system to monitor Bornean orangutan (Pongo pygmaeus wurmbii) long calls.

      PubMed

      Spillmann, Brigitte; van Noordwijk, Maria A; Willems, Erik P; Mitra Setia, Tatang; Wipfli, Urs; van Schaik, Carel P

      2015-07-01

      The long call is an important vocal communication signal in the widely dispersed, semi-solitary orangutan. Long calls affect individuals' ranging behavior and mediate social relationships and regulate encounters between dispersed individuals in a dense rainforest. The aim of this study was to test the utility of an Acoustic Location System (ALS) for recording and triangulating the loud calls of free-living primates. We developed and validated a data extraction protocol for an ALS used to record wild orangutan males' long calls at the Tuanan field site (Central Kalimantan). We installed an ALS in a grid of 300 ha, containing 20 SM2+ recorders placed in a regular lattice at 500 m intervals, to monitor the distribution of calling males in the area. The validated system had the following main features: (i) a user-trained software algorithm (Song Scope) that reliably recognized orangutan long calls from sound files at distances up to 700 m from the nearest recorder, resulting in a total area of approximately 900 ha that could be monitored continuously; (ii) acoustic location of calling males up to 200 m outside the microphone grid, which meant that within an area of approximately 450 ha, call locations could be calculated through triangulation. The mean accuracy was 58 m, an error that is modest relative to orangutan mobility and average inter-individual distances. We conclude that an ALS is a highly effective method for detecting long-distance calls of wild primates and triangulating their position. In combination with conventional individual focal follow data, an ALS can greatly improve our knowledge of orangutans' social organization, and is readily adaptable for studying other highly vocal animals. PMID:25773926

    20. Comparative evaluation of Space Transportation System (STS)-3 flight and acoustic test random vibration response of the OSS-1 payload

      NASA Technical Reports Server (NTRS)

      On, F. J.

      1983-01-01

      A comparative evaluation of the Space Transportation System (STS)-3 flight and acoustic test random vibration response of the Office of Space Science-1 (OSS-1) payload is presented. The results provide insight into the characteristics of vibroacoustic response of pallet payload components in the payload bay during STS flights.

    1. NASA/Army Rotorcraft Technology. Volume 2: Materials and Structures, Propulsion and Drive Systems, Flight Dynamics and Control, and Acoustics

      NASA Technical Reports Server (NTRS)

      1988-01-01

      The Conference Proceedings is a compilation of over 30 technical papers presented which report on the advances in rotorcraft technical knowledge resulting from NASA, Army, and industry research programs over the last 5 to 10 years. Topics addressed in this volume include: materials and structures; propulsion and drive systems; flight dynamics and control; and acoustics.

    2. Active Control of Jet Noise Using High Resolution TRPIV Part 2: Velocity-Pressure-Acoustic Correlations

      NASA Astrophysics Data System (ADS)

      Low, Kerwin; Kostka, Stanislav; Berger, Zachary; Berry, Matthew; Gogineni, Sivaram; Glauser, Mark

      2011-11-01

      We investigate the pressure, velocity and acoustic field of a transonic jet. Test conditions comprise a 2 inch nozzle, analyzing two flow speeds, Mach 0.6 and 0.85, with open loop control explored for the Mach 0.6 case. We make simultaneous measurements of the near-field pressure and far-field acoustics at 40 kHz, alongside 10 kHz time resolved PIV measurements in the r-z plane. Cross correlations are performed exploring how both the near-field Fourier filtered pressure and low dimensional POD modes relate to the far-field acoustics. Of interest are those signatures witch exhibit the strongest correlation with far-field, and subsequently how these structures can be controlled. The goal is to investigate how flow-induced perturbations, via synthetic jet actuators, of the developing shear layer might bring insight into how one may alter the flow such that the far-field acoustic signature is mitigated. The TR-PIV measurements will prove to be a powerful tool in being able to track the propagation of physical structures for both the controlled and uncontrolled jet.

    3. PREFACE: ARENA 2006—Acoustic and Radio EeV Neutrino detection Activities

      NASA Astrophysics Data System (ADS)

      Thompson, Lee

      2007-06-01

      The International Conference on Acoustic and Radio EeV Neutrino Activities, ARENA 2006 was jointly hosted by the Universities of Northumbria and Sheffield at the City of Newcastle Campus of the University of Northumbria in June 2006. ARENA 2006 was the latest in a series of meetings which have addressed, either separately or jointly, the use of radio and acoustic sensors for the detection of highly relativistic particles. Previous successful meetings have taken place in Los Angeles (RADHEP, 2000), Stanford (2003) and DESY Zeuthen (ARENA 2005). A total of 50 scientists from across Europe, the US and Japan attended the conference presenting status reports and results from a number of projects and initiatives spread as far afield as the Sweden and the South Pole. The talks presented at the meeting and the proceedings contained herein represent a `snapshot' of the status of the fields of acoustic and radio detection at the time of the conference. The three day meeting also included two invited talks by Dr Paula Chadwick and Dr Johannes Knapp who gave excellent summaries of the related astroparticle physics fields of high energy gamma ray detection and high energy cosmic ray detection respectively. As well as a full academic agenda there were social events including a Medieval themed conference banquet at Lumley Castle and a civic reception kindly provided by the Lord Mayor of Newcastle and hosted at the Mansion House. Thanks must go to the International Advisory Board members for their input and guidance, the Local Organising Committee for their hard work in bringing everything together and finally the delegates for the stimulating, enthusiastic and enjoyable spirit in which ARENA 2006 took place. Lee Thompson

      International Advisory Board

      G. Anton, ErlangenD. Besson, Kansas
      J. Blümer, KarlsruheA. Capone, Rome
      H. Falcke, BonnP. Gorham, Hawaii
      G. Gratta

    4. Elements for a conformity assessment system in acoustics, vibrations and ultrasound in Mexico

      NASA Astrophysics Data System (ADS)

      Echeverria-Villagomez, Salvador; Elias-Juarez, Alfredo

      2002-11-01

      Conformity assessment in acoustics, vibrations, and ultrasound have great relevance for human health, safety, and environmental protection. Due to this fact, it is usually the government and public agencies that promote, together with the National Standards Institute (NSI) and representatives from the whole society, the development and continuous updating of standards and regulations. Besides appropriate regulations, conformity evaluation requires the existence and fitness of, at least, two other elements: adequate measuring capabilities and a proper system of consequences. The measuring capabilities are embodied in the infrastructure that goes from the National Metrology Institute (NMI) to the calibration and testing laboratories and verification units. The system of consequences, the means by which compliance with regulations can be verified and required, can be established by the same government and public agencies (GPA) of the field of work in which the regulation has been developed. In Mexico, a conformity assessment system of this kind has been evolving rapidly during the past 10 years, since the establishment of CENAM. The paper will present a proposed conformity assessment system, arising from a comparison of the Mexican system with those of other countries.

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

      PubMed

      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. PMID:20805059

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

      NASA Technical Reports Server (NTRS)

      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, USA. 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, USA. 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.

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

      NASA Technical Reports Server (NTRS)

      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.

    8. Nonlinear Acoustics in Fluids

      NASA Astrophysics Data System (ADS)

      Lauterborn, Werner; Kurz, Thomas; Akhatov, Iskander

      At high sound intensities or long propagation distances at in fluids sufficiently low damping acoustic phenomena become nonlinear. This chapter focuses on nonlinear acoustic wave properties in gases and liquids. The origin of nonlinearity, equations of state, simple nonlinear waves, nonlinear acoustic wave equations, shock-wave formation, and interaction of waves are presented and discussed. Tables are given for the nonlinearity parameter B/A for water and a range of organic liquids, liquid metals and gases. Acoustic cavitation with its nonlinear bubble oscillations, pattern formation and sonoluminescence (light from sound) are modern examples of nonlinear acoustics. The language of nonlinear dynamics needed for understanding chaotic dynamics and acoustic chaotic systems is introduced.

    9. Acoustic monitoring system to quantify ingestive behavior of free-grazing cattle

      Technology Transfer Automated Retrieval System (TEKTRAN)

      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...

    10. Systems and methods of monitoring acoustic pressure to detect a flame condition in a gas turbine

      SciTech Connect

      Ziminsky, Willy Steve; Krull, Anthony Wayne; Healy, Timothy Andrew , Yilmaz, Ertan

      2011-05-17

      A method may detect a flashback condition in a fuel nozzle of a combustor. The method may include obtaining a current acoustic pressure signal from the combustor, analyzing the current acoustic pressure signal to determine current operating frequency information for the combustor, and indicating that the flashback condition exists based at least in part on the current operating frequency information.

    11. A robust calibration technique for acoustic emission systems based on momentum transfer from a ball drop

      USGS Publications Warehouse

      McLaskey, Gregory C.; Lockner, David A.; Kilgore, Brian D.; Beeler, Nicholas M.

      2015-01-01

      We describe a technique to estimate the seismic moment of acoustic emissions and other extremely small seismic events. Unlike previous calibration techniques, it does not require modeling of the wave propagation, sensor response, or signal conditioning. Rather, this technique calibrates the recording system as a whole and uses a ball impact as a reference source or empirical Green’s function. To correctly apply this technique, we develop mathematical expressions that link the seismic moment $M_{0}$ of internal seismic sources (i.e., earthquakes and acoustic emissions) to the impulse, or change in momentum $\\Delta p $, of externally applied seismic sources (i.e., meteor impacts or, in this case, ball impact). We find that, at low frequencies, moment and impulse are linked by a constant, which we call the force‐moment‐rate scale factor $C_{F\\dot{M}} = M_{0}/\\Delta p$. This constant is equal to twice the speed of sound in the material from which the seismic sources were generated. Next, we demonstrate the calibration technique on two different experimental rock mechanics facilities. The first example is a saw‐cut cylindrical granite sample that is loaded in a triaxial apparatus at 40 MPa confining pressure. The second example is a 2 m long fault cut in a granite sample and deformed in a large biaxial apparatus at lower stress levels. Using the empirical calibration technique, we are able to determine absolute source parameters including the seismic moment, corner frequency, stress drop, and radiated energy of these magnitude −2.5 to −7 seismic events.

    12. Noninvasive Ultrasonic Examination Technology in Support of Counter-Terrorism and Drug Interdiction Activities: the Acoustic Inspection Device (AID)

      SciTech Connect

      Diaz, Aaron A.; Burghard, Brion J.; Skorpik, James R.; Shepard, Chester L.; Samuel, Todd J.; Pappas, Richard A.

      2003-07-16

      The Pacific Northwest National Laboratory (PNNL) has developed a portable, battery-operated handheld ultrasonic device that provides non-invasive container interrogation and material identification capabilities. The Acoustic Inspection Device (AID) performs an automated analysis of the return echoes to identify the material, and detect contraband in the form of submerged packages and concealed compartments in liquid filled containers and solid-form commodities. This device utilizes a database consisting of material property measurements acquired from an automated ultrasonic fluid characterization system called the Velocity-Attenuation Measurement System (VAMS).

    13. Assessing Acoustic Sound Levels Associated with Active Source Seismic Surveys in Shallow Marine Environments

      NASA Astrophysics Data System (ADS)

      Bohnenstiehl, D. R.; Tolstoy, M.; Thode, A.; Diebold, J. B.; Webb, S. C.

      2004-12-01

      The potential effect of active source seismic research on marine mammal populations is a topic of increasing concern, and controversy surrounding such operations has begun to impact the planning and permitting of academic surveys [e.g., Malakoff, 2002 Science]. Although no causal relationship between marine mammal strandings and seismic exploration has been proven, any circumstantial evidence must be thoroughly investigated. A 2002 stranding of two beaked whales in the Gulf of California within 50 km of a R/V Ewing seismic survey has been a subject of concern for both marine seismologists and environmentalists. In order to better understand possible received levels for whales in the vicinity of these operations, modeling is combined with ground-truth calibration measurements. A wide-angle parabolic equation model, which is capable of including shear within the sediment and basement layers, is used to generate predictive models of low-frequency transmission loss within the Gulf of California. This work incorporates range-dependent bathymetry, sediment thickness, sound velocity structure and sub-bottom properties. Oceanic sounds speed profiles are derived from the U.S. Navy's seasonal GDEM model and sediment thicknesses are taken from NOAA's worldwide database. The spectral content of the Ewing's 20-airgun seismic array is constrained by field calibration in the spring of 2003 [Tolstoy et al., 2004 GRL], indicating peak energies at frequencies below a few hundred Hz, with energy spectral density showing an approximate power-law decrease at higher frequencies (being ~40 dB below peak at 1 kHz). Transmission loss is estimated along a series of radials extending from multiple positions along the ship's track, with the directivity of the array accounted for by phase-shifting point sources that are scaled by the cube root of the individual airgun volumes. This allows the time-space history of low-frequency received levels to be reconstructed within the Gulf of California

    14. Time-reversal acoustic focusing system as a virtual random phased array.

      PubMed

      Sarvazyan, Armen; Fillinger, Laurent; Gavrilov, Leonid

      2010-04-01

      This paper compares the performance of two different systems for dynamic focusing of ultrasonic waves: conventional 2-D phased arrays (PA) and a focusing system based on the principles of time-reversed acoustics (TRA). Focused ultrasound fields obtained in the experiments with the TRA focusing system (TRA FS), which employs a liquid-filled reverberator with 4 piezotransducers attached to its wall, are compared with the focused fields obtained by mathematical simulation of PAs comprised from several tens to several hundreds of elements distributed randomly on the array surface. The experimental and simulated focusing systems had the same aperture and operated at a frequency centered about 600 kHz. Experimental results demonstrated that the TRA FS with a small number of channels can produce complex focused patterns and can steer them with efficiency comparable to that of a PA with hundreds of elements. It is shown that the TRA FS can be realized using an extremely simple means, such as a reverberator made of a water-filled plastic bottle with just a few piezotransducers attached to its walls. PMID:20378444

    15. Surface acoustic wave sensor array system for trace organic vapor detection using pattern recognition analysis

      NASA Astrophysics Data System (ADS)

      Rose-Pehrsson, Susan L.; Grate, Jay W.; Klusty, Mark

      1993-03-01

      A sensor system using surface acoustic wave (SAW) vapor sensors has been fabricated and tested against hazardous organic vapors, simulants of these vapors, and potential background vapors. The vapor tests included two- and three-component mixtures, and covered a wide relative humidity range. The sensor system was compared of four SAW devices coated with different sorbent materials with different vapor selectivities. Preconcentrators were included to improve sensitivity. The vapor experiments were organized into a large data set analyzed using pattern recognition techniques. Pattern recognition algorithms were developed to identify two different classes of hazards. The algorithms were verified against a second data set not included in the training. Excellent sensitivity was achieved by the sensor coatings, and the pattern recognition analysis, and was also examined by the preconcentrators. The system can detect hazardous vapors of interest in the ppb range even in varying relative humidity and in the presence of background vapors. The system does not false alarm to a variety of other vapors including gasoline, jet fuel, diesel fuel and cigarette smoke.

    16. A wireless demodulation system for passive surface acoustic wave torque sensor

      NASA Astrophysics Data System (ADS)

      Ji, Xiaojun; Fan, Yanping; Qi, Hongli; Chen, Jing; Han, Tao; Cai, Ping

      2014-12-01

      Surface acoustic wave (SAW) resonators are utilized as torque sensors for their passive and wireless features. However, the response of a SAW torque sensor is difficult to detect because of the transient response duration and interruption of channel noise, which limit the application of SAW torque sensors. The sensitive mechanism and response function of a passive wireless SAW torque sensor are analyzed in this study. A novel demodulation system involving both hardware and software is developed for the SAW torque sensor. A clipping amplifier is utilized in the hardware to widen the dynamic response range and increase the length of the valid signal. Correlation extension and centroid algorithms are designed to lengthen the received signal and improve the estimation accuracy of the center frequency of the response signal, respectively. Meanwhile, a fast binary search algorithm is proposed to accelerate the scanning cycle according to the developed response function. Finally, the SAW torque sensor demodulation system is set up and SAW resonators with high sensitivity are fabricated on a quartz substrate. The presented demodulation system is tested, and a standard deviation of 0.28 kHz is achieved. This value is much smaller than that of classic and modern spectrum estimation methods. The sensitivity of resonance frequency shift versus torque on the shaft of the assembled senor is 2.03 kHz/Nm; the coefficient of determination is 0.999, and the linearity is 0.87%. Experimental results verify the validity and feasibility of the proposed SAW torque sensor demodulation system.

    17. Remote ballistic emplacement of an electro-optical and acoustic target detection and localization system

      NASA Astrophysics Data System (ADS)

      West, Aaron; Mellini, Mark

      2015-05-01

      Near real time situational awareness in uncontrolled non line of sight (NLOS) and beyond line of sight (BLOS) environments is critical in the asymmetric battlefield of future conflicts. The ability to detect and accurately locate hostile forces in difficult terrain or urban environments can dramatically increase the survivability and effectiveness of dismounted soldiers, especially when they are limited to the resources available only to the small unit. The Sensor Mortar Network (SMortarNet) is a 60mm Intelligence, Surveillance, and Reconnaissance (ISR) mortar designed to give the Squad near real time situational awareness in uncontrolled NLOS environments. SMortarNet is designed to track targets both acoustically and electro optically and can fuse tracks between, the acoustic, EO, and magnetic modalities on board. The system is linked to other mortar nodes and the user via a masterless frequency hopping spread spectrum ad-hoc mesh radio network. This paper will discuss SMortarNet in the context of a squad level dismounted soldier, its technical capabilities, and its benefit to the small unit Warfighter. The challenges with ballistic remote emplacement of sensitive components and the on board signal processing capabilities of the system will also be covered. The paper will also address how the sensor network can be integrated with existing soldier infrastructure, such as the NettWarrior platform, for rapid transition to soldier systems. Networks of low power sensors can have many forms, but the more practical networks for warfighters are ad hoc radio-based systems that can be rapidly deployed and can leverage a range of assets available at a given time. The low power long life networks typically have limited bandwidth and may have unreliable communication depending on the network health, which makes autonomous sensors a critical component of the network. SMortarNet reduces data to key information features at the sensor itself. The smart sensing approach enables

    18. An Alignment Method for the Integration of Underwater 3D Data Captured by a Stereovision System and an Acoustic Camera

      PubMed Central

      Lagudi, Antonio; Bianco, Gianfranco; Muzzupappa, Maurizio; Bruno, Fabio

      2016-01-01

      The integration of underwater 3D data captured by acoustic and optical systems is a promising technique in various applications such as mapping or vehicle navigation. It allows for compensating the drawbacks of the low resolution of acoustic sensors and the limitations of optical sensors in bad visibility conditions. Aligning these data is a challenging problem, as it is hard to make a point-to-point correspondence. This paper presents a multi-sensor registration for the automatic integration of 3D data acquired from a stereovision system and a 3D acoustic camera in close-range acquisition. An appropriate rig has been used in the laboratory tests to determine the relative position between the two sensor frames. The experimental results show that our alignment approach, based on the acquisition of a rig in several poses, can be adopted to estimate the rigid transformation between the two heterogeneous sensors. A first estimation of the unknown geometric transformation is obtained by a registration of the two 3D point clouds, but it ends up to be strongly affected by noise and data dispersion. A robust and optimal estimation is obtained by a statistical processing of the transformations computed for each pose. The effectiveness of the method has been demonstrated in this first experimentation of the proposed 3D opto-acoustic camera. PMID:27089344

    19. An Alignment Method for the Integration of Underwater 3D Data Captured by a Stereovision System and an Acoustic Camera.

      PubMed

      Lagudi, Antonio; Bianco, Gianfranco; Muzzupappa, Maurizio; Bruno, Fabio

      2016-01-01

      The integration of underwater 3D data captured by acoustic and optical systems is a promising technique in various applications such as mapping or vehicle navigation. It allows for compensating the drawbacks of the low resolution of acoustic sensors and the limitations of optical sensors in bad visibility conditions. Aligning these data is a challenging problem, as it is hard to make a point-to-point correspondence. This paper presents a multi-sensor registration for the automatic integration of 3D data acquired from a stereovision system and a 3D acoustic camera in close-range acquisition. An appropriate rig has been used in the laboratory tests to determine the relative position between the two sensor frames. The experimental results show that our alignment approach, based on the acquisition of a rig in several poses, can be adopted to estimate the rigid transformation between the two heterogeneous sensors. A first estimation of the unknown geometric transformation is obtained by a registration of the two 3D point clouds, but it ends up to be strongly affected by noise and data dispersion. A robust and optimal estimation is obtained by a statistical processing of the transformations computed for each pose. The effectiveness of the method has been demonstrated in this first experimentation of the proposed 3D opto-acoustic camera. PMID:27089344

    20. The multipath propagation effect in gunshot acoustics and its impact on the design of sniper positioning systems

      NASA Astrophysics Data System (ADS)

      Ramos, António L. L.; Holm, Sverre; Gudvangen, Sigmund; Otterlei, Ragnvald

      2013-06-01

      Counter sniper systems rely on the detection and parameter estimation of the shockwave and the muzzle blast in order to determine the sniper location. In real-world situations, these acoustical signals can be disturbed by natural phenomena like weather and climate conditions, multipath propagation effect, and background noise. While some of these issues have received some attention in recent publications with application to gunshot acoustics, the multipath propagation phenomenon whose effect can not be neglected, specially in urban environments, has not yet been discussed in details in the technical literature in the same context. Propagating sound waves can be reflected at the boundaries in the vicinity of sound sources or receivers, whenever there is a difference in acoustical impedance between the reflective material and the air. Therefore, the received signal can be composed of a direct-path signal plus N scaled delayed copies of that signal. This paper presents a discussion on the multipath propagation effect and its impact on the performance and reliability of sniper positioning systems. In our formulation, propagation models for both the shockwave and the muzzle blast are considered and analyzed. Conclusions following the theoretical analysis of the problem are fully supported by actual gunshots acoustical signatures.

      1. Patterns of Occurrence and Marine Mammal Acoustic Behavior in Relation to Navy Sonar Activity Off Jacksonville, Florida.

        PubMed

        Oswald, Julie N; Norris, Thomas F; Yack, Tina M; Ferguson, Elizabeth L; Kumar, Anurag; Nissen, Jene; Bell, Joel

        2016-01-01

        Passive acoustic data collected from marine autonomous recording units deployed off Jacksonville, FL (from 13 September to 8 October 2009 and 3 December 2009 to 8 January 2010), were analyzed for detection of cetaceans and Navy sonar. Cetaceans detected included Balaenoptera acutorostrata, Eubalaena glacialis, B. borealis, Physeter macrocephalus, blackfish, and delphinids. E. glacialis were detected at shallow and, somewhat unexpectedly, deep sites. P. macrocephalus were characterized by a strong diel pattern. B. acutorostrata showed the strongest relationship between sonar activity and vocal behavior. These results provide a preliminary assessment of cetacean occurrence off Jacksonville and new insights on vocal responses to sonar. PMID:26611034

      2. Parametrized data-driven decomposition for bifurcation analysis, with application to thermo-acoustically unstable systems

        NASA Astrophysics Data System (ADS)

        Sayadi, Taraneh; Schmid, Peter J.; Richecoeur, Franck; Durox, Daniel

        2015-03-01

        Dynamic mode decomposition (DMD) belongs to a class of data-driven decomposition techniques, which extracts spatial modes of a constant frequency from a given set of numerical or experimental data. Although the modal shapes and frequencies are a direct product of the decomposition technique, the determination of the respective modal amplitudes is non-unique. In this study, we introduce a new algorithm for defining these amplitudes, which is capable of capturing physical growth/decay rates of the modes within a transient signal and is otherwise not straightforward using the standard DMD algorithm. In addition, a parametric DMD algorithm is introduced for studying dynamical systems going through a bifurcation. The parametric DMD alleviates multiple applications of the DMD decomposition to the system with fixed parametric values by including the bifurcation parameter in the decomposition process. The parametric DMD with amplitude correction is applied to a numerical and experimental data sequence taken from thermo-acoustically unstable systems. Using DMD with amplitude correction, we are able to identify the dominant modes of the transient regime and their respective growth/decay rates leading to the final limit-cycle. In addition, by applying parametrized DMD to images of an oscillating flame, we are able to identify the dominant modes of the bifurcation diagram.

      3. Detection of nonlinear distortions in the vibration of acoustically driven mechanical systems using heterodyne vibrometry

        NASA Astrophysics Data System (ADS)

        Aerts, J. R. M.; Dirckx, J. J. J.; Pintelon, R.

        2008-06-01

        Recently, a measurement set-up was presented to detect small nonlinear distortions in the vibration of acoustically driven mechanical systems. A speaker generates a specially designed multisine excitation signal that drives the vibration of a test object. The generated sound pressure is measured with a probe microphone in front of the test object, and an heterodyne vibrometer measures the corresponding vibration. Due to the high degree of linearity of the heterodyne technique, very small nonlinear distortions can be detected. In this paper the set-up is used to verify whether small nonlinear distortions are present in the vibration of the middle ear system, which is classically considered to be a completely linear system. In vitro measurements on the right ear of an adult male gerbil proved that nonlinear distortions are present in the vibration of the tympanic membrane. Similar results were seen in measurements on the left ear. The influence of post-mortem changes on the nonlinear behaviour of the middle ear was verified in a number of successive measurements. These indicated that the nonlinear behaviour of the middle ear decreases in time.

      4. Test-bench system for a borehole azimuthal acoustic reflection imaging logging tool

        NASA Astrophysics Data System (ADS)

        Liu, Xianping; Ju, Xiaodong; Qiao, Wenxiao; Lu, Junqiang; Men, Baiyong; Liu, Dong

        2016-06-01

        The borehole azimuthal acoustic reflection imaging logging tool (BAAR) is a new generation of imaging logging tool, which is able to investigate stratums in a relatively larger range of space around the borehole. The BAAR is designed based on the idea of modularization with a very complex structure, so it has become urgent for us to develop a dedicated test-bench system to debug each module of the BAAR. With the help of a test-bench system introduced in this paper, test and calibration of BAAR can be easily achieved. The test-bench system is designed based on the client/server model. The hardware system mainly consists of a host computer, an embedded controlling board, a bus interface board, a data acquisition board and a telemetry communication board. The host computer serves as the human machine interface and processes the uploaded data. The software running on the host computer is designed based on VC++. The embedded controlling board uses Advanced Reduced Instruction Set Machines 7 (ARM7) as the micro controller and communicates with the host computer via Ethernet. The software for the embedded controlling board is developed based on the operating system uClinux. The bus interface board, data acquisition board and telemetry communication board are designed based on a field programmable gate array (FPGA) and provide test interfaces for the logging tool. To examine the feasibility of the test-bench system, it was set up to perform a test on BAAR. By analyzing the test results, an unqualified channel of the electronic receiving cabin was discovered. It is suggested that the test-bench system can be used to quickly determine the working condition of sub modules of BAAR and it is of great significance in improving production efficiency and accelerating industrial production of the logging tool.

      5. Acoustic Monitoring System for Frog Population Estimation Using In-Situ Progressive Learning

        NASA Astrophysics Data System (ADS)

        Aboudan, Adam

        Frog populations are considered excellent bio-indicators and hence the ability to monitor changes in their populations can be very useful for ecological research and environmental monitoring. This thesis presents a new population estimation approach based on the recognition of individual frogs of the same species, namely the Pseudacris Regilla (Pacific Chorus Frog), which does not rely on the availability of prior training data. An in-situ progressive learning algorithm is developed to determine whether an incoming call belongs to a previously detected individual frog or a newly encountered individual frog. A temporal call overlap detector is also presented as a pre-processing tool to eliminate overlapping calls. This is done to prevent the degrading of the learning process. The approach uses Mel-frequency cepstral coefficients (MFCCs) and multivariate Gaussian models to achieve individual frog recognition. In the first part of this thesis, the MFCC as well as the related linear predictive cepstral coefficients (LPCC) acoustic feature extraction processes are reviewed. The Gaussian mixture models (GMM) are also reviewed as an extension to the classical Gaussian modeling used in the proposed approach. In the second part of this thesis, the proposed frog population estimation system is presented and discussed in detail. The proposed system involves several different components including call segmentation, feature extraction, overlap detection, and the in-situ progressive learning process. In the third part of the thesis, data description and system performance results are provided. The process of synthetically generating test sequences of real frog calls, which are applied to the proposed system for performance analysis, is described. Also, the results of the system performance are presented which show that the system is successful in distinguishing individual frogs, hence capable of providing reasonable estimates of the frog population. The system can readily be

      6. Generalized acoustic energy density based active noise control in single frequency diffuse sound fields.

        PubMed

        Xu, Buye; Sommerfeldt, Scott D

        2014-09-01

        In a diffuse sound field, prior research has established that a secondary source can theoretically achieve perfect cancellation at an error microphone in the far field of the secondary source. However, the sound pressure level is generally only reduced in a small zone around the error sensor, and at a distance half of a wavelength away from the error sensor, the averaged sound pressure level will be increased by more than 10 dB. Recently an acoustic energy quantity, referred to as the generalized acoustic energy density (GED), has been introduced. The GED is obtained by using a weighting factor in the formulation of total acoustic energy density. Different values of the weighting factor can be chosen for different applications. When minimizing the GED at the error sensor, one can adjust the weighting factor to increase the spatial extent of the "quiet zone" and to achieve a desired balance between the degree of attenuation in the quiet zone and the total energy added into the sound field. PMID:25190386

      7. Acoustic Cluster Therapy: In Vitro and Ex Vivo Measurement of Activated Bubble Size Distribution and Temporal Dynamics.

        PubMed

        Healey, Andrew John; Sontum, Per Christian; Kvåle, Svein; Eriksen, Morten; Bendiksen, Ragnar; Tornes, Audun; Østensen, Jonny

        2016-05-01

        Acoustic cluster technology (ACT) is a two-component, microparticle formulation platform being developed for ultrasound-mediated drug delivery. Sonazoid microbubbles, which have a negative surface charge, are mixed with micron-sized perfluoromethylcyclopentane droplets stabilized with a positively charged surface membrane to form microbubble/microdroplet clusters. On exposure to ultrasound, the oil undergoes a phase change to the gaseous state, generating 20- to 40-μm ACT bubbles. An acoustic transmission technique is used to measure absorption and velocity dispersion of the ACT bubbles. An inversion technique computes bubble size population with temporal resolution of seconds. Bubble populations are measured both in vitro and in vivo after activation within the cardiac chambers of a dog model, with catheter-based flow through an extracorporeal measurement flow chamber. Volume-weighted mean diameter in arterial blood after activation in the left ventricle was 22 μm, with no bubbles >44 μm in diameter. After intravenous administration, 24.4% of the oil is activated in the cardiac chambers. PMID:26831341

      8. Evaluation of SHM System Produced by Additive Manufacturing via Acoustic Emission and Other NDT Methods

        PubMed Central

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

        2015-01-01

        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. PMID:26506349

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

        PubMed

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

        2015-01-01

        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. PMID:26506349

      10. Evidence from acoustic imaging for submarine volcanic activity in 2012 off the west coast of El Hierro (Canary Islands, Spain)

        NASA Astrophysics Data System (ADS)

        Pérez, Nemesio M.; Somoza, Luis; Hernández, Pedro A.; de Vallejo, Luis González; León, Ricardo; Sagiya, Takeshi; Biain, Ander; González, Francisco J.; Medialdea, Teresa; Barrancos, José; Ibáñez, Jesús; Sumino, Hirochika; Nogami, Kenji; Romero, Carmen

        2014-12-01

        We report precursory geophysical, geodetic, and geochemical signatures of a new submarine volcanic activity observed off the western coast of El Hierro, Canary Islands. Submarine manifestation of this activity has been revealed through acoustic imaging of submarine plumes detected on the 20-kHz chirp parasound subbottom profiler (TOPAS PS18) mounted aboard the Spanish RV Hespérides on June 28, 2012. Five distinct "filament-shaped" acoustic plumes emanating from the flanks of mounds have been recognized at water depth between 64 and 88 m on a submarine platform located NW El Hierro. These plumes were well imaged on TOPAS profiles as "flares" of high acoustic contrast of impedance within the water column. Moreover, visible plumes composed of white rafts floating on the sea surface and sourcing from the location of the submarine plumes were reported by aerial photographs on July 3, 2012, 5 days after acoustic plumes were recorded. In addition, several geophysical and geochemical data support the fact that these submarine vents were preceded by several precursory signatures: (i) a sharp increase of the seismic energy release and the number of daily earthquakes of magnitude ≥2.5 on June 25, 2012, (ii) significant vertical and horizontal displacements observed at the Canary Islands GPS network (Nagoya University-ITER-GRAFCAN) with uplifts up to 3 cm from June 25 to 26, 2012, (iii) an anomalous increase of the soil gas radon activity, from the end of April until the beginning of June reaching peak values of 2.7 kBq/m3 on June 3, 2012, and (iv) observed positive peak in the air-corrected value of 3He/4He ratio monitored in ground waters (8.5 atmospheric 3He/4He ratio ( R A)) at the northwestern El Hierro on June 16, 2012. Combining these submarine and subaerial information, we suggest these plumes are the consequence of submarine vents exhaling volcanic gas mixed with fine ash as consequence of an event of rapid rise of volatile-rich magma beneath the NW submarine ridge

      11. The binaural performance of a cross-talk cancellation system with matched or mismatched setup and playback acoustics

        PubMed Central

        Akeroyd, Michael A.; Chambers, John; Bullock, David; Palmer, Alan R.; Summerfield, A. Quentin; Nelson, Philip A.; Gatehouse, Stuart

        2013-01-01

        Cross-talk cancellation is a method for synthesising virtual auditory space using loudspeakers. One implementation is the “Optimal Source Distribution” technique [T. Takeuchi and P. Nelson, J. Acoust. Soc. Am. 112, 2786-2797 (2002)], in which the audio bandwidth is split across three pairs of loudspeakers, placed at azimuths of ±90°, ±15°, and ±3°, conveying low, mid and high frequencies, respectively. A computational simulation of this system was developed and verified against measurements made on an acoustic system using a manikin. Both the acoustic system and the simulation gave a wideband average cancellation of almost 25 dB. The simulation showed that when there was a mismatch between the head-related transfer functions used to set up the system and those of the final listener, the cancellation was reduced to an average of 13 dB. Moreover, in this case the binaural ITDs and ILDs delivered by the simulation of the OSD system often differed from the target values. It is concluded that only when the OSD system is set up with “matched” head-related transfer functions can it deliver accurate binaural cues. PMID:17348528

      12. Portable active interrogation system.

        SciTech Connect

        Moss, C. E.; Brener, M. W.; Hollas, C. L.; Myers, W. L.

        2004-01-01

        The system consists of a pulsed DT neutron generator (5 x 10{sup 7} n/s) and a portable but high intrinsic efficiency, custom-designed, polyethylene-moderated {sup 3}He neutron detector. A multichannel scaler card in a ruggedized laptop computer acquires the data. A user-friendly LabVIEW program analyzes and displays the data. The program displays a warning message when highly enriched uranium or any other fissionable materials is detected at a specified number of sigmas above background in the delayed region between pulses. This report describes the system and gives examples of the response of the system to highly enriched uranium and some other fissionable materials, at several distances and with various shielding materials.

      13. Investigation of Hydraulic Fracture Propagation Using a Post-Peak Control System Coupled with Acoustic Emission

        NASA Astrophysics Data System (ADS)

        Chen, Li-Hsien; Chen, Wei-Chih; Chen, Yao-Chung; Benyamin, Leo; Li, An-Jui

        2015-05-01

        This study investigates the fracture mechanism of fluid coupled with a solid resulting from hydraulic fracture. A new loading machine was designed to improve upon conventional laboratory hydraulic fracture testing and to provide a means of better understanding fracture behavior of solid media. Test specimens were made of cement mortar. An extensometer and acoustic emission (AE) monitoring system recorded the circumferential deformation and crack growth location/number during the test. To control the crack growth at the post-peak stage the input fluid rate can be adjusted automatically according to feedback from the extensometer. The complete stress-deformation curve, including pre- and post-peak stages, was therefore obtained. The crack extension/growth developed intensively after the applied stress reached the breakdown pressure. The number of cracks recorded by the AE monitoring system was in good agreement with the amount of deformation (expansion) recorded by the extensometer. The results obtained in this paper provide a better understanding of the hydraulic fracture mechanism which is useful for underground injection projects.

      14. System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

        DOEpatents

        Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

        2002-01-01

        Low power EM waves are used to detect motions of vocal tract tissues of the human speech system before, during, and after voiced speech. A voiced excitation function is derived. The excitation function provides speech production information to enhance speech characterization and to enable noise removal from human speech.

      15. Optimality criteria-based topology optimization of a bi-material model for acoustic-structural coupled systems

        NASA Astrophysics Data System (ADS)

        Shang, Linyuan; Zhao, Guozhong

        2016-06-01

        This article investigates topology optimization of a bi-material model for acoustic-structural coupled systems. The design variables are volume fractions of inclusion material in a bi-material model constructed by the microstructure-based design domain method (MDDM). The design objective is the minimization of sound pressure level (SPL) in an interior acoustic medium. Sensitivities of SPL with respect to topological design variables are derived concretely by the adjoint method. A relaxed form of optimality criteria (OC) is developed for solving the acoustic-structural coupled optimization problem to find the optimum bi-material distribution. Based on OC and the adjoint method, a topology optimization method to deal with large calculations in acoustic-structural coupled problems is proposed. Numerical examples are given to illustrate the applications of topology optimization for a bi-material plate under a low single-frequency excitation and an aerospace structure under a low frequency-band excitation, and to prove the efficiency of the adjoint method and the relaxed form of OC.

      16. On the recognition of compromise in sensing systems: rewired acoustic arrays and distorted route estimation and classification

        NASA Astrophysics Data System (ADS)

        Thornley, David J.; Damarla, Thyagaraju; Srivastava, Mani B.; Mylaraswami, Dinkar

        2009-09-01

        A group of acoustic arrays that provide direction of approach estimates also support classification of vehicles using the beams formed during that estimation. Successful simultaneous tracking and classification has demonstrated the value of such a sensing resource as a UGS installation. We now consider potential attacks on the integrity of such an installation, describing the effect of compromised acoustic arrays in the data analysis and tracking and classification results. We indicate how these can be automatically recognized, and note that calibration methods intended for deployment time can be used for recovery during operation, which opens the door to methods for recovery from the compromise without re-configuring the equipment, using abductive reasoning to discover the necessary re-processing structure. By rotating an acoustic array, the tracking stability and implied path of a tracked entity can be distorted while leaving the data and analysis from individual arrays self-consistent. Less structured modifications, such as unstructured re-ordering of microphone connections, impact the basic data analysis. We examine the effect of these classes of attack on the integrity of a set of unattended acoustic arrays, and consider the steps necessary for detection, diagnosis, and recovering an effective sensing system. Understaning these steps plays an important part in reasoning in support of balance of investment, planning, operation and post-hoc analysis.

      17. Switchable and tunable film bulk acoustic resonator fabricated using barium strontium titanate active layer and Ta2O5/SiO2 acoustic reflector

        NASA Astrophysics Data System (ADS)

        Sbrockey, N. M.; Kalkur, T. S.; Mansour, A.; Khassaf, H.; Yu, H.; Aindow, M.; Alpay, S. P.; Tompa, G. S.

        2016-08-01

        A solidly mounted acoustic resonator was fabricated using a Ba0.60Sr0.40TiO3 (BST) film deposited by metal organic chemical vapor deposition. The device was acoustically isolated from the substrate using a Bragg reflector consisting of three pairs of Ta2O5/SiO2 layers deposited by chemical solution deposition. Transmission electron microscopy verified that the Bragg reflector was not affected by the high temperatures and oxidizing conditions necessary to process high quality BST films. Electrical characterization of the resonator demonstrated a quality factor (Q) of 320 and an electromechanical coupling coefficient (Kt2) of 7.0% at 11 V.

      18. Acoustic Translation of an Acoustically Levitated Sample

        NASA Technical Reports Server (NTRS)

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

        1986-01-01

        Acoustic-levitation apparatus uses only one acoustic mode to move sample from one region of chamber to another. Sample heated and cooled quickly by translation between hot and cold regions of levitation chamber. Levitated sample is raised into furnace region by raising plunger. Frequency of sound produced by transducers adjusted by feedback system to maintain (102) resonant mode, which levitates sample midway between transducers and plunger regardless of plunger position.

      19. Acoustic Neuroma

        MedlinePlus

        An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...

      20. Differences in foraging activity of deep sea diving odontocetes in the Ligurian Sea as determined by passive acoustic recorders

        NASA Astrophysics Data System (ADS)

        Giorli, Giacomo; Au, Whitlow W. L.; Neuheimer, Anna

        2016-01-01

        Characterizing the trophic roles of deep-diving odontocete species and how they vary in space and time is challenged by our ability to observe foraging behavior. Though sampling methods are limited, foraging activity of deep-diving odontocetes can be monitored by recording their biosonar emissions. Daily occurrence of echolocation clicks was monitored acoustically for five months (July-December 2011) in the Ligurian Sea (Mediterranean Sea) using five passive acoustic recorders. Detected odontocetes included Cuvier's beaked whales (Zipuhius cavirostris), sperm whales (Physeter macrocephalus), Risso's dolphins (Grampus griseus), and long-finned pilot whales (Globicephala melas). The results indicated that the foraging strategies varied significantly over time, with sperm whales switching to nocturnal foraging in late September whereas Risso's dolphins and pilot whales foraged mainly at night throughout the sampling period. In the study area, winter nights are about five hours longer than summer nights and an analysis showed that pilot whales and Risso's dolphins adjusted their foraging activity with the length of the night, foraging longer during the longer winter nights. This is the first study to show that marine mammals exhibit diurnal foraging patterns closely correlated to sunrise and sunset.

      1. Detecting the activation of a self-healing mechanism in concrete by acoustic emission and digital image correlation.

        PubMed

        Tsangouri, E; Aggelis, D G; Van Tittelboom, K; De Belie, N; Van Hemelrijck, D

        2013-01-01

        Autonomous crack healing in concrete is obtained when encapsulated healing agent is embedded into the material. Cracking damage in concrete elements ruptures the capsules and activates the healing process by healing agent release. Previously, the strength and stiffness recovery as well as the sealing efficiency after autonomous crack repair was well established. However, the mechanisms that trigger capsule breakage remain unknown. In parallel, the conditions under which the crack interacts with embedded capsules stay black-box. In this research, an experimental approach implementing an advanced optical and acoustic method sets up scopes to monitor and justify the crack formation and capsule breakage of concrete samples tested under three-point bending. Digital Image Correlation was used to visualize the crack opening. The optical information was the basis for an extensive and analytical study of the damage by Acoustic Emission analysis. The influence of embedding capsules on the concrete fracture process, the location of capsule damage, and the differentiation between emissions due to capsule rupture and crack formation are presented in this research. A profound observation of the capsules performance provides a clear view of the healing activation process. PMID:24381518

      2. A wireless demodulation system for passive surface acoustic wave torque sensor.

        PubMed

        Ji, Xiaojun; Fan, Yanping; Qi, Hongli; Chen, Jing; Han, Tao; Cai, Ping

        2014-12-01

        Surface acoustic wave (SAW) resonators are utilized as torque sensors for their passive and wireless features. However, the response of a SAW torque sensor is difficult to detect because of the transient response duration and interruption of channel noise, which limit the application of SAW torque sensors. The sensitive mechanism and response function of a passive wireless SAW torque sensor are analyzed in this study. A novel demodulation system involving both hardware and software is developed for the SAW torque sensor. A clipping amplifier is utilized in the hardware to widen the dynamic response range and increase the length of the valid signal. Correlation extension and centroid algorithms are designed to lengthen the received signal and improve the estimation accuracy of the center frequency of the response signal, respectively. Meanwhile, a fast binary search algorithm is proposed to accelerate the scanning cycle according to the developed response function. Finally, the SAW torque sensor demodulation system is set up and SAW resonators with high sensitivity are fabricated on a quartz substrate. The presented demodulation system is tested, and a standard deviation of 0.28 kHz is achieved. This value is much smaller than that of classic and modern spectrum estimation methods. The sensitivity of resonance frequency shift versus torque on the shaft of the assembled senor is 2.03 kHz/Nm; the coefficient of determination is 0.999, and the linearity is 0.87%. Experimental results verify the validity and feasibility of the proposed SAW torque sensor demodulation system. PMID:25554317

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

        NASA Astrophysics Data System (ADS)

        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. Method and system for generating a beam of acoustic energy from a borehole, and applications thereof

        DOEpatents

        Johnson Paul A.; Ten Cate, James A.; Guyer, Robert; Le Bas, Pierre-Yves; Vu, Cung; Nihei, Kurt; Schmitt, Denis P.; Skelt, Christopher

        2012-02-14

        A compact array of transducers is employed as a downhole instrument for acoustic investigation of the surrounding rock formation. The array is operable to generate simultaneously a first acoustic beam signal at a first frequency and a second acoustic beam signal at a second frequency different than the first frequency. These two signals can be oriented through an azimuthal rotation of the array and an inclination rotation using control of the relative phases of the signals from the transmitter elements or electromechanical linkage. Due to the non-linearity of the formation, the first and the second acoustic beam signal mix into the rock formation where they combine into a collimated third signal that propagates in the formation along the same direction than the first and second signals and has a frequency equal to the difference of the first and the second acoustic signals. The third signal is received either within the same borehole, after reflection, or another borehole, after transmission, and analyzed to determine information about rock formation. Recording of the third signal generated along several azimuthal and inclination directions also provides 3D images of the formation, information about 3D distribution of rock formation and fluid properties and an indication of the dynamic acoustic non-linearity of the formation.

      5. Acoustic Seal

        NASA Technical Reports Server (NTRS)

        Steinetz, Bruce M. (Inventor)

        2006-01-01

        The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

      6. Acoustic seal

        NASA Technical Reports Server (NTRS)

        Steinetz, Bruce M. (Inventor)

        2006-01-01

        The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

      7. A rail system for circular synthetic aperture sonar imaging and acoustic target strength measurements: Design/operation/preliminary results

        NASA Astrophysics Data System (ADS)

        Kennedy, J. L.; Marston, T. M.; Lee, K.; Lopes, J. L.; Lim, R.

        2014-01-01

        A 22 m diameter circular rail, outfitted with a mobile sonar tower trolley, was designed, fabricated, instrumented with underwater acoustic transducers, and assembled on a 1.5 m thick sand layer at the bottom of a large freshwater pool to carry out sonar design and target scattering response studies. The mobile sonar tower translates along the rail via a drive motor controlled by customized LabVIEW software. The rail system is modular and assembly consists of separately deploying eight circular arc sections, measuring a nominal center radius of 11 m and 8.64 m arc length each, and having divers connect them together in the underwater environment. The system enables full scale measurements on targets of interest with 0.1° angular resolution over a complete 360° aperture, without disrupting target setup, and affording a level of control over target environment conditions and noise sources unachievable in standard field measurements. In recent use, the mobile cart carrying an instrumented sonar tower was translated along the rail in 720 equal position increments and acoustic backscatter data were acquired at each position. In addition, this system can accommodate both broadband monostatic and bistatic scattering measurements on targets of interest, allowing capture of target signature phenomena under diverse configurations to address current scientific and technical issues encountered in mine countermeasure and unexploded ordnance applications. In the work discussed here, the circular rail apparatus is used for acoustic backscatter testing, but this system also has the capacity to facilitate the acquisition of magnetic and optical sensor data from targets of interest. A brief description of the system design and operation will be presented along with preliminary processed results for data acquired from acoustic measurements conducted at the Naval Surface Warfare Center, Panama City Division Test Pond Facility. [Work Supported by the U.S. Office of Naval Research and

      8. A rail system for circular synthetic aperture sonar imaging and acoustic target strength measurements: design/operation/preliminary results.

        PubMed

        Kennedy, J L; Marston, T M; Lee, K; Lopes, J L; Lim, R

        2014-01-01

        A 22 m diameter circular rail, outfitted with a mobile sonar tower trolley, was designed, fabricated, instrumented with underwater acoustic transducers, and assembled on a 1.5 m thick sand layer at the bottom of a large freshwater pool to carry out sonar design and target scattering response studies. The mobile sonar tower translates along the rail via a drive motor controlled by customized LabVIEW software. The rail system is modular and assembly consists of separately deploying eight circular arc sections, measuring a nominal center radius of 11 m and 8.64 m arc length each, and having divers connect them together in the underwater environment. The system enables full scale measurements on targets of interest with 0.1° angular resolution over a complete 360° aperture, without disrupting target setup, and affording a level of control over target environment conditions and noise sources unachievable in standard field measurements. In recent use, the mobile cart carrying an instrumented sonar tower was translated along the rail in 720 equal position increments and acoustic backscatter data were acquired at each position. In addition, this system can accommodate both broadband monostatic and bistatic scattering measurements on targets of interest, allowing capture of target signature phenomena under diverse configurations to address current scientific and technical issues encountered in mine countermeasure and unexploded ordnance applications. In the work discussed here, the circular rail apparatus is used for acoustic backscatter testing, but this system also has the capacity to facilitate the acquisition of magnetic and optical sensor data from targets of interest. A brief description of the system design and operation will be presented along with preliminary processed results for data acquired from acoustic measurements conducted at the Naval Surface Warfare Center, Panama City Division Test Pond Facility. [Work Supported by the U.S. Office of Naval Research and

      9. Coupling and simulation of acoustic fluid-structure interaction systems using localized Lagrange multipliers

        NASA Astrophysics Data System (ADS)

        Ross, Mike R.

        This thesis presents a new coupling method for treating the interaction of an acoustic fluid with a flexible structure, with emphasis on handling spatially non-matching meshes. It is based on the Localized Lagrange Multiplier (LLM) method. A frame is introduced as a "mediator" or "information relay" device between the fluid and the structure at the interaction surface. The frame is discretized in terms of kinematic variables. A Lagrange multiplier field is introduced between the frame and the structure, and another one between the frame and the fluid. The function of the multiplier pair is weak enforcement of kinematic continuity. This configuration completely decouples the structure and fluid models, because each model communicates to the frame through node collocated multipliers and not directly to each other. In order to assure proper communication, energy formulations of the fluid and structure models are in terms of displacements and associated time derivatives. A novel transformation of the fluid displacement model into a fluid displacement potential model enforces the irrotational condition of the acoustic fluid. This transformation reduces the number of degrees of freedom in two and three-dimensions and is suitable for both vibration and transient analyses. The LLM method facilitates the construction of separate discretizations using different mesh generation programs, as well as use of customized time integration methods. To advance the solution in time, the LLM coupling method is combined with a partitioned solution procedure. The time-stepping computations are organized in a way that eliminates the traditional prediction step characteristic of staggered solution procedures. This is accomplished by solving for the interface variables: Lagrange multipliers and frame states, and then feeding this solution back to the coupled components. This sequence forestalls the well-known stability degradation caused by prediction, yet it retains the desirable

      10. A Permanent Automated Real-Time Passive Acoustic Monitoring System for Bottlenose Dolphin Conservation in the Mediterranean Sea

        PubMed Central

        Brunoldi, Marco; Bozzini, Giorgio; Casale, Alessandra; Corvisiero, Pietro; Grosso, Daniele; Magnoli, Nicodemo; Alessi, Jessica; Bianchi, Carlo Nike; Mandich, Alberta; Morri, Carla; Povero, Paolo; Wurtz, Maurizio; Melchiorre, Christian; Viano, Gianni; Cappanera, Valentina; Fanciulli, Giorgio; Bei, Massimiliano; Stasi, Nicola; Taiuti, Mauro

        2016-01-01

        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. PMID:26789265

      11. A Permanent Automated Real-Time Passive Acoustic Monitoring System for Bottlenose Dolphin Conservation in the Mediterranean Sea.

        PubMed

        Brunoldi, Marco; Bozzini, Giorgio; Casale, Alessandra; Corvisiero, Pietro; Grosso, Daniele; Magnoli, Nicodemo; Alessi, Jessica; Bianchi, Carlo Nike; Mandich, Alberta; Morri, Carla; Povero, Paolo; Wurtz, Maurizio; Melchiorre, Christian; Viano, Gianni; Cappanera, Valentina; Fanciulli, Giorgio; Bei, Massimiliano; Stasi, Nicola; Taiuti, Mauro

        2016-01-01

        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. PMID:26789265

      12. Identifying open and closed system behaviors at Tungurahua volcano (Ecuador) using SO2 and seismo-acoustic measurements

        NASA Astrophysics Data System (ADS)

        Hidalgo, Silvana; Battaglia, Jean; Bernard, Benjamin; Steele, Alexander; Arellano, Santiago; Galle, Bo

        2014-05-01

        Tungurahua is one of the most active volcanoes in Ecuador. It is located in Central Ecuador, 160 km South of Quito and 8 km South of the touristic town of Baños. Tungurahua had one eruption every century since 1500, with an activity characterized by ash fallouts and pyroclastic and lava flows. The current eruptive period of Tungurahua began in 1999 with multiple episodes of explosive activity that have threatened the local population. The monitoring network is constituted by 5 short period and 5 broadband seismic stations, 4 DOAS permanent instruments, 4 tiltmeters, 2 permanent high resolution GPS, 4 digital cameras and 10 acoustic flow monitors. The correct interpretation of the different data acquired by this network allows a better understanding of the eruptive behavior of Tungurahua in order to provide early warning to the local population. Tungurahua changed its behavior from a continuously erupting volcano, as it was until 2008, to a sporadically erupting one, showing clear quiescence phases lasting from 40 to 184 days, and intense activity phases lasting from 15 to 70 days. Activity phases are characterized by Strombolian and Vulcanian eruptive styles, producing ash fallouts and in a few occasions pyroclastic flows. In terms of hazard to the local population, one of the goals of monitoring Tungurahura is to forecast the onset and evolution of eruptive phases. In particular the occurrence of large Vulcanian explosions which occur when the conduit is closed is a major issue. Since 2010 we focused our study on the relation between SO2 gas emissions, the seismic and acoustic energies of explosions and the tremor amplitudes. The first observation of comparing these different datasets is that the correlation between seismic and SO2 degassing is not straightforward, and actually the relation reflects the conditions at the vent: open or closed. The onset of eruptive phases in open conduit conditions can be identified which leads to an effective eruption forecasting

      13. Development of a portable multiphoton photo-acoustic spectroscopy system for tumor diagnostics

        NASA Astrophysics Data System (ADS)

        Chandrasekharan, Nirmala; Kiser, John B.; Cullum, Brian M.

        2004-12-01

        In this paper we describe the development of a novel fiber optic probe for subsurface tumor diagnostics, based on non-resonant multiphoton photoacoustic spectroscopy (NMPPAS). In this technique, endogenous biomarkers present in tissues are irradiated in the near infrared, using a tunable high-power laser. The resulting multiphoton excitation events are detected as an acoustic (i.e. ultrasonic) signal, using an ultrasonic piezoelectric transducer. The signal from the piezoelectric transducer is then corrected for laser power fluctuations by normalizing the NMPPAS signal at each wavelength with the laser intensity recorded, from an optical diode. By scanning the laser excitation over the appropriate wavelength range for the tissue of interest, absorption differences between normal and tumor tissues can be measured and analyzed. The fiber optic probe was characterized and optimized for transmission efficiency as well as its time dependent response to high power laser pulses. The focusing optics were optimized and a piezoelectric transducer film detector chosen based on its sensitivity in the ultrasonic frequency range of interest. Using this probe system NMPPAS measurements were performed on several common fluorescent dyes including rhodamine 6G as well as well-characterized biomarkers like tryptophan. Furthermore, the technique was further successfully applied to the differentiation of tumorous and healthy human brain tissues.

      14. Surface Acoustic Wave Study of Exciton Condensation in Bilayer Quantum Hall Systems

        NASA Astrophysics Data System (ADS)

        Pollanen, J.; Eisenstein, J. P.; Pfeiffer, L. N.; West, K. W.

        In bilayer two-dimensional electron systems (2DES) in GaAs a strongly correlated many-electron state forms at low temperature and high magnetic field when the total electron density nT becomes equal to the degeneracy of a single spin split Landau level. This state corresponds to a total filling factor νT = 1 and can be described in terms of pseudospin ferromagnetism, or equivalently, Bose condensation of bilayer excitons. We have simultaneously measured magneto-transport and the propagation of pulsed surface acoustic waves (SAWs) at a frequency of 747 MHz to explore the phase transition between two independent layers at νT = 1 / 2 + 1 / 2 and the correlated state at νT = 1 in a high quality double quantum well device. We tune through this transition by varying the total electron density in our device with front and backside electrostatic gates. We acknowledge funding provided by the Institute for Quantum Information and Matter, an NSF Physics Frontiers Center (NFS Grant PHY-1125565) with support of the Gordon and Betty Moore Foundation (GBMF-12500028).

      15. Acoustic interactions between inversion symmetric and asymmetric two-level systems

        NASA Astrophysics Data System (ADS)

        Churkin, A.; Barash, D.; Schechter, M.

        2014-08-01

        Amorphous solids, as well as many disordered lattices, display remarkable universality in their low temperature acoustic properties. This universality is attributed to the attenuation of phonons by tunneling two-level systems (TLSs), facilitated by the interaction of the TLSs with the phonon field. TLS-phonon interaction also mediates effective TLS-TLS interactions, which dictates the existence of a glassy phase and its low energy properties. Here we consider KBr:CN, the archetypal disordered lattice showing universality. We calculate numerically, using conjugate gradients method, the effective TLS-TLS interactions for inversion symmetric (CN flips) and asymmetric (CN rotations) TLSs, in the absence and presence of disorder, in two and three dimensions. The observed dependence of the magnitude and spatial power law of the interaction on TLS symmetry, and its change with disorder, characterizes TLS-TLS interactions in disordered lattices in both extreme and moderate dilutions. Our results are in good agreement with the two-TLS model, recently introduced to explain long-standing questions regarding the quantitative universality of phonon attenuation and the energy scale of ≈1-3 K below which universality is observed.

      16. PYRETHROID INSECTICIDES AND THE GAMMA-AMINOBUTYRIC ACID (ALPHA) RECEPTOR COMPLEX: MOTOR ACTIVITY AND THE ACOUSTIC STARTLE RESPONSE IN THE RAT (JOURNAL VERSION)

        EPA Science Inventory

        Two behavioral tests, locomotor activity and the acoustic startle response (ASR), were utilized to test for dose-addition of cismethrin, a Type I, or deltamethrin, a Type II pyrethroid, with compounds active to the gamma-aminobutryic acid (GABA) receptor complex (picrotoxin, musc...

      17. A PDE-based methodology for modeling, parameter estimation and feedback control in structural and structural acoustic systems

        NASA Technical Reports Server (NTRS)

        Banks, H. T.; Brown, D. E.; Metcalf, Vern L.; Silcox, R. J.; Smith, Ralph C.; Wang, Yun

        1994-01-01

        A problem of continued interest concerns the control of vibrations in a flexible structure and the related problem of reducing structure-borne noise in structural acoustic systems. In both cases, piezoceramic patches bonded to the structures have been successfully used as control actuators. Through the application of a controlling voltage, the patches can be used to reduce structural vibrations which in turn lead to methods for reducing structure-borne noise. A PDE-based methodology for modeling, estimating physical parameters, and implementing a feedback control scheme for problems of this type is discussed. While the illustrating example is a circular plate, the methodology is sufficiently general so as to be applicable in a variety of structural and structural acoustic systems.

      18. Digital data-acquisition system for measuring the free decay of acoustical standing waves in a resonant tube

        NASA Technical Reports Server (NTRS)

        Meredith, R. W.; Zuckerwar, A. J.

        1984-01-01

        A low-cost digital system based on an 8-bit Apple II microcomputer has been designed to provide on-line control, data acquisition, and evaluation of sound absorption measurements in gases. The measurements are conducted in a resonant tube, in which an acoustical standing wave is excited, the excitation removed, and the sound absorption evaluated from the free decay envelope. The free decay is initiated from the computer keyboard after the standing wave is established, and the microphone response signal is the source of the analog signal for the A/D converter. The acquisition software is written in ASSEMBLY language and the evaluation software in BASIC. This paper describes the acoustical measurement, hardware, software, and system performance and presents measurements of sound absorption in air as an example.

      19. A Multi-Transducer Near Field Acoustic Levitation System for Noncontact Transportation of Large-Sized Planar Objects

        NASA Astrophysics Data System (ADS)

        Amano, Takafumi; Koike, Yoshikazu; Nakamura, Kentaro; Ueha, Sadayuki; Hashimoto, Yoshiki

        2000-05-01

        A new noncontact transportation system, which consists of multiple ultrasonic transducers and operates based on near-field acoustic levitation, is proposed to transport a large-sized planar object such as a glass substrate for liquid crystal devices. Using the proposed systems consisting of two and three transducers, the suspension characteristics of the levitated objects are studied as functions of both size difference and angles between the vibration systems and the levitated object. As a result, the holding force is proved to increase as the angle increases and is maximum when the horizontal dimensions of the system and the object coincide.

      20. Exploiting flow to control the in vitro spatiotemporal distribution of microbubble-seeded acoustic cavitation activity in ultrasound therapy.

        PubMed

        Pouliopoulos, Antonios N; Bonaccorsi, Simone; Choi, James J

        2014-11-21

        Focused ultrasound and microbubbles have been extensively used to generate therapeutic bioeffects. Despite encouraging in vivo results, there remains poor control of the magnitude and spatial distribution of these bioeffects due to the limited ability of conventional pulse shapes and sequences to control cavitation dynamics. Thus current techniques are restricted by an efficacy-safety trade-off. The primary aim of the present study was to incorporate the presence of flow in the design of new short pulse sequences, which can more uniformly distribute the cavitation activity. Microbubbles flowing (fluid velocity: 10 mm s(-1)) through a 300 μm tube were sonicated with a focused 0.5 MHz transducer while acoustic emissions were captured with an inserted focused 7.5 MHz passive cavitation detector. The two foci were co-axially aligned and their focal points were overlapped. Whereas conventional sequences are composed of a long burst (>10,000 cycles) emitted at a low burst repetition frequency (<10 Hz), we decomposed this burst into short pulses by adding intervals to facilitate inter-pulse microbubble movement. To evaluate how this sequence influenced cavitation distribution, we emitted short pulses (peak-rarefactional pressure (PRP): 40-366 kPa, pulse length (PL): 5-25 cycles) at high pulse repetition frequencies (PRF: 0.625-10 kHz) for a burst length of 100 ms. Increased cavitation persistence, implied by the duration of the microbubble acoustic emissions, was a measure of improved distribution due to the presence of flow. Sonication at lower acoustic pressures, longer pulse intervals and lower PLs improved the spatial distribution of cavitation. Furthermore, spectral analysis of the microbubble emissions revealed that the improvement at low pressures is due to persisting stable cavitation. In conclusion, new short-pulse sequences were shown to improve spatiotemporal control of acoustic cavitation dynamics during physiologically relevant flow. This

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

        NASA Astrophysics Data System (ADS)

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

        2015-07-01

        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-TechTM; a finite element based analysis, monitoring and fitness for service assessment system. Integri-TechTM 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-TechTM software to calculate source location using its own built-in algorithm, and this was verified independently using a MATLAB approach.

      2. Highly directional acoustic receivers.

        PubMed

        Cray, Benjamin A; Evora, Victor M; Nuttall, Albert H

        2003-03-01

        The theoretical directivity of a single combined acoustic receiver, a device that can measure many quantities of an acoustic field at a collocated point, is presented here. The formulation is developed using a Taylor series expansion of acoustic pressure about the origin of a Cartesian coordinate system. For example, the quantities measured by a second-order combined receiver, denoted a dyadic sensor, are acoustic pressure, the three orthogonal components of acoustic particle velocity, and the nine spatial gradients of the velocity vector. The power series expansion, which can be of any order, is cast into an expression that defines the directivity of a single receiving element. It is shown that a single highly directional dyadic sensor can have a directivity index of up to 9.5 dB. However, there is a price to pay with highly directive sensors; these sensors can be significantly more sensitive to nonacoustic noise sources. PMID:12656387

      3. Acoustic Remote Sensing

        NASA Astrophysics Data System (ADS)

        Dowling, David R.; Sabra, Karim G.

        2015-01-01

        Acoustic waves carry information about their source and collect information about their environment as they propagate. This article reviews how these information-carrying and -collecting features of acoustic waves that travel through fluids can be exploited for remote sensing. In nearly all cases, modern acoustic remote sensing involves array-recorded sounds and array signal processing to recover multidimensional results. The application realm for acoustic remote sensing spans an impressive range of signal frequencies (10-2 to 107 Hz) and distances (10-2 to 107 m) and involves biomedical ultrasound imaging, nondestructive evaluation, oil and gas exploration, military systems, and Nuclear Test Ban Treaty monitoring. In the past two decades, approaches have been developed to robustly localize remote sources; remove noise and multipath distortion from recorded signals; and determine the acoustic characteristics of the environment through which the sound waves have traveled, even when the recorded sounds originate from uncooperative sources or are merely ambient noise.

      4. Virtual acoustics displays

        NASA Technical Reports Server (NTRS)

        Wenzel, Elizabeth M.; Fisher, Scott S.; Stone, Philip K.; Foster, Scott H.

        1991-01-01

        The real time acoustic display capabilities are described which were developed for the Virtual Environment Workstation (VIEW) Project at NASA-Ames. The acoustic display is capable of generating localized acoustic cues in real time over headphones. An auditory symbology, a related collection of representational auditory 'objects' or 'icons', can be designed using ACE (Auditory Cue Editor), which links both discrete and continuously varying acoustic parameters with information or events in the display. During a given display scenario, the symbology can be dynamically coordinated in real time with 3-D visual objects, speech, and gestural displays. The types of displays feasible with the system range from simple warnings and alarms to the acoustic representation of multidimensional data or events.

      5. Cochlear bionic acoustic metamaterials

        NASA Astrophysics Data System (ADS)

        Ma, Fuyin; Wu, Jiu Hui; Huang, Meng; Fu, Gang; Bai, Changan

        2014-11-01

        A design of bionic acoustic metamaterial and acoustic functional devices was proposed by employing the mammalian cochlear as a prototype. First, combined with the experimental data in previous literatures, it is pointed out that the cochlear hair cells and stereocilia cluster are a kind of natural biological acoustic metamaterials with the negative stiffness characteristics. Then, to design the acoustic functional devices conveniently in engineering application, a simplified parametric helical structure was proposed to replace actual irregular cochlea for bionic design, and based on the computational results of such a bionic parametric helical structure, it is suggested that the overall cochlear is a local resonant system with the negative dynamic effective mass characteristics. There are many potential applications in the bandboard energy recovery device, cochlear implant, and acoustic black hole.

      6. A cabled acoustic telemetry system for detecting and tracking juvenile salmon: part 1. Engineering design and instrumentation.

        PubMed

        Weiland, Mark A; Deng, Z Daniel; Seim, Tom A; LaMarche, Brian L; Choi, Eric Y; Fu, Tao; Carlson, Thomas J; Thronas, Aaron I; Eppard, M Brad

        2011-01-01

        In 2001 the U.S. Army Corps of Engineers, Portland District (OR, USA), started developing the Juvenile Salmon Acoustic Telemetry System, a nonproprietary sensing technology, to meet the needs for monitoring the survival of juvenile salmonids through eight large hydroelectric facilities within the Federal Columbia River Power System (FCRPS). Initial development focused on coded acoustic microtransmitters and autonomous receivers that could be deployed in open reaches of the river for detection of the juvenile salmonids implanted with microtransmitters as they passed the autonomous receiver arrays. In 2006, the Pacific Northwest National Laboratory began the development of an acoustic receiver system for deployment at hydropower facilities (cabled receiver) for detecting fish tagged with microtransmitters as well as tracking them in two or three dimensions for determining route of passage and behavior as the fish passed at the facility. The additional information on route of passage, combined with survival estimates, is used by the dam operators and managers to make structural and operational changes at the hydropower facilities to improve survival of fish as they pass the facilities through the FCRPS. PMID:22163918

      7. Benthic microbial fuel cell as direct power source for an acoustic modem and seawater oxygen/temperature sensor system.

        PubMed

        Gong, Yanming; Radachowsky, Sage E; Wolf, Michael; Nielsen, Mark E; Girguis, Peter R; Reimers, Clare E

        2011-06-01

        Supported by the natural potential difference between anoxic sediment and oxic seawater, benthic microbial fuel cells (BMFCs) promise to be ideal power sources for certain low-power marine sensors and communication devices. In this study a chambered BMFC with a 0.25 m(2) footprint was used to power an acoustic modem interfaced with an oceanographic sensor that measures dissolved oxygen and temperature. The experiment was conducted in Yaquina Bay, Oregon over 50 days. Several improvements were made in the BMFC design and power management system based on lessons learned from earlier prototypes. The energy was harvested by a dynamic gain charge pump circuit that maintains a desired point on the BMFC's power curve and stores the energy in a 200 F supercapacitor. The system also used an ultralow power microcontroller and quartz clock to read the oxygen/temperature sensor hourly, store data with a time stamp, and perform daily polarizations. Data records were transmitted to the surface by the acoustic modem every 1-5 days after receiving an acoustic prompt from a surface hydrophone. After jump-starting energy production with supplemental macroalgae placed in the BMFC's anode chamber, the average power density of the BMFC adjusted to 44 mW/m(2) of seafloor area which is better than past demonstrations at this site. The highest power density was 158 mW/m(2), and the useful energy produced and stored was ≥ 1.7 times the energy required to operate the system. PMID:21545151

      8. A cabled acoustic telemetry system for detecting and tracking juvenile salmon: Part 1. Engineering design and instrumentation

        SciTech Connect

        Weiland, Mark A.; Deng, Zhiqun; Seim, Thomas A.; Lamarche, Brian L.; Choi, Eric Y.; Fu, Tao; Carlson, Thomas J.; Thronas, Aaron I.; Eppard, Matthew B.

        2011-05-26

        The U.S. Army Corps of Engineers-Portland District started development of the Juvenile Salmon Acoustic Telemetry System (JSATS), a nonproprietary technology, in 2001 to meet the needs for monitoring the survival of juvenile salmonids through the 31 federal dams in the Federal Columbia River Power System (FCRPS). Initial development focused on coded acoustic microtransmitters, and autonomous receivers that could be deployed in open reaches of the river for detection of the juvenile salmonids implanted with microtransmitters as they passed the autonomous receiver arrays. In 2006 the Pacific Northwest National Laboratory (PNNL) was tasked with development of an acoustic receiver system for deployment at hydropower facilities (cabled receiver) for detecting fish tagged with microtransmitters as well as tracking them in 2 or 3-dimensions as the fish passed at the facility for determining route of passage. The additional route of passage information, combined with survival estimates, is used by the dam operators and managers to make structural and operational changes at the hydropower facilities to improve survival of fish as they pass the facilities and through the FCRPS.

      9. A Cabled Acoustic Telemetry System for Detecting and Tracking Juvenile Salmon: Part 1. Engineering Design and Instrumentation

        PubMed Central

        Weiland, Mark A.; Deng, Z. Daniel; Seim, Tom A.; LaMarche, Brian L.; Choi, Eric Y.; Fu, Tao; Carlson, Thomas J.; Thronas, Aaron I.; Eppard, M. Brad

        2011-01-01

        In 2001 the U.S. Army Corps of Engineers, Portland District (OR, USA), started developing the Juvenile Salmon Acoustic Telemetry System, a nonproprietary sensing technology, to meet the needs for monitoring the survival of juvenile salmonids through eight large hydroelectric facilities within the Federal Columbia River Power System (FCRPS). Initial development focused on coded acoustic microtransmitters and autonomous receivers that could be deployed in open reaches of the river for detection of the juvenile salmonids implanted with microtransmitters as they passed the autonomous receiver arrays. In 2006, the Pacific Northwest National Laboratory began the development of an acoustic receiver system for deployment at hydropower facilities (cabled receiver) for detecting fish tagged with microtransmitters as well as tracking them in two or three dimensions for determining route of passage and behavior as the fish passed at the facility. The additional information on route of passage, combined with survival estimates, is used by the dam operators and managers to make structural and operational changes at the hydropower facilities to improve survival of fish as they pass the facilities through the FCRPS. PMID:22163918

      10. Active control of passive acoustic fields: passive synthetic aperture/Doppler beamforming with data from an autonomous vehicle.

        PubMed

        D'Spain, Gerald L; Terrill, Eric; Chadwell, C David; Smith, Jerome A; Lynch, Stephen D

        2006-12-01

        The maneuverability of autonomous underwater vehicles (AUVs) equipped with hull-mounted arrays provides the opportunity to actively modify received acoustic fields to optimize extraction of information. This paper uses ocean acoustic data collected by an AUV-mounted two-dimensional hydrophone array, with overall dimension one-tenth wavelength at 200-500 Hz, to demonstrate aspects of this control through vehicle motion. Source localization is performed using Doppler shifts measured at a set of receiver velocities by both single elements and a physical array. Results show that a source in the presence of a 10-dB higher-level interferer having exactly the same frequency content (as measured by a stationary receiver) is properly localized and that white-noise-constrained adaptive beamforming applied to the physical aperture data in combination with Doppler beamforming provides greater spatial resolution than physical-aperture-alone beamforming and significantly lower sidelobes than single element Doppler beamforming. A new broadband beamformer that adjusts for variations in vehicle velocity on a sample by sample basis is demonstrated with data collected during a high-acceleration maneuver. The importance of including the cost of energy expenditure in determining optimal vehicle motion is demonstrated through simulation, further illustrating how the vehicle characteristics are an integral part of the signal/array processing structure. PMID:17225392

      11. Abnormal cortical sensorimotor activity during "Target" sound detection in subjects with acute acoustic trauma sequelae: an fMRI study.

        PubMed

        Job, Agnès; Pons, Yoann; Lamalle, Laurent; Jaillard, Assia; Buck, Karl; Segebarth, Christoph; Delon-Martin, Chantal

        2012-03-01

        The most common consequences of acute acoustic trauma (AAT) are hearing loss at frequencies above 3 kHz and tinnitus. In this study, we have used functional Magnetic Resonance Imaging (fMRI) to visualize neuronal activation patterns in military adults with AAT and various tinnitus sequelae during an auditory "oddball" attention task. AAT subjects displayed overactivities principally during reflex of target sound detection, in sensorimotor areas and in emotion-related areas such as the insula, anterior cingulate and prefrontal cortex, in premotor area, in cross-modal sensory associative areas, and, interestingly, in a region of the Rolandic operculum that has recently been shown to be involved in tympanic movements due to air pressure. We propose further investigations of this brain area and fine middle ear investigations, because our results might suggest a model in which AAT tinnitus may arise as a proprioceptive illusion caused by abnormal excitability of middle-ear muscle spindles possibly link with the acoustic reflex and associated with emotional and sensorimotor disturbances. PMID:22574285

      12. Characterization of a Multi-element Clinical HIFU System Using Acoustic Holography and Nonlinear Modeling

        PubMed Central

        Kreider, Wayne; Yuldashev, Petr V.; Sapozhnikov, Oleg A.; Farr, Navid; Partanen, Ari; Bailey, Michael R.; Khokhlova, Vera A.

        2014-01-01

        High-intensity focused ultrasound (HIFU) is a treatment modality that relies on the delivery of acoustic energy to remote tissue sites to induce thermal and/or mechanical tissue ablation. To ensure the safety and efficacy of this medical technology, standard approaches are needed for accurately characterizing the acoustic pressures generated by clinical ultrasound sources under operating conditions. Characterization of HIFU fields is complicated by nonlinear wave propagation and the complexity of phased-array transducers. Previous work has described aspects of an approach that combines measurements and modeling, and here we demonstrate this approach for a clinical phased array transducer. First, low-amplitude hydrophone measurements were performed in water over a scan plane between the array and the focus. Second, these measurements were used to holographically reconstruct the surface vibrations of the transducer and to set a boundary condition for a 3-D acoustic propagation model. Finally, nonlinear simulations of the acoustic field were carried out over a range of source power levels. Simulation results were compared to pressure waveforms measured directly by hydrophone at both low and high power levels, demonstrating that details of the acoustic field including shock formation are quantitatively predicted. PMID:25004539

      13. Application of Acoustic-Electric Interaction for Neuro-Muscular Activity Mapping: A Review

        PubMed Central

        Gunnlaugsdottir, Kristin Inga

        2015-01-01

        Acousto-electric interaction signal (AEI signal) resulting from interaction of acoustic pressure wave and electrical current field has received recent attention in biomedical field for detection and registration of bioelectrical current. The signal is very of small value and brings about several challenges when detecting it. Several observations has been done in saline solution and on nerves and tissues under controlled condition that give optimistic indication about its utilization. Ultrasound Current Source Density Imaging (UCSDI) has been introduced, that uses the AEI signal to image the current distribution. This review provides an overview of the investigations on the AEI signal and USCDI imaging that has been made, their results and several considerations on the limitations and future possibilities on using the acousto-electric interaction signal. PMID:26913142

      14. Bottlebrush and comb-like elastomers as ultra-soft electrical and acoustically active materials

        NASA Astrophysics Data System (ADS)

        Daniel, William; Vatankhah-Varnosfaderani, Mohammad; Pandya, Ashish; Burdynska, Joanna; Morgan, Benjamin; Everhart, Matthew; Matyjaszewski, Krzysztof; Dobrynin, Andrey; Rubinstein, Michael; Sheiko, Sergei; UNC MIRT Team

        Without swelling in a solvent, it is challenging to obtain materials with a modulus below 105 Pa, which is dictated by chain entanglements. We show that macromolecules can be disentangled by dense grafting of side chains to long polymer chains. The bottlebrush and comb-like architectures demonstrate a unique combination of flexibility and network dilution, leading to significant decrease of the entanglement modulus (Ge) and increase of extensibility. Following theoretical predictions, it has been shown that the Ge is controlled by the polymerization degrees of sidechains (nsc) and grafting spacer (ng) as Ge ~ (ng /nsc) 1 . 5 . Using the reduced entanglement density, we developed solvent-free elastomers with moduli on the order of 100 Pa and excellent extensibility. Using bottlebrush architectures we have developed PDMS dielectric actuators with high deformation at low electric field strength. Additionally strong acoustic adsorption leads to materials showing shape and volume control in light opaque environments. NSF (DMR 1409710, DMR 1122483, DMR 1407645, and DMR 1436201).

      15. A multiple case study for calibrating acoustic backscatter to total suspended material in a large river system

        NASA Astrophysics Data System (ADS)

        Gunkel, Brittany Lynne

        Sediment transport measurements are determined using techniques such as bed-material and suspended-sediment sampling, and more recently the conversion of acoustic backscatter (ABS). Acoustic waves scatter and attenuate while passing through a water-sediment mixture and the backscatter is converted to sediment concentration, size, and shape. A multiple case study performed using data from West Bay, Old River, and Mississippi River at Vicksburg show the variability of a large river system TSM flux during assorted hydrographs and two methods (CHL and moving boat) capture the events. After processing and applying the two methods the results showed that the methods are typically within 8% to 41% of each other when computing sediment flux. The conversion of total suspended material (TSM) from ABS was an average of 0.2% to 69% from the sample TSM. Peak part of the hydrograph had the highest average suspended sediment concentration (SSC) and descending had the lowest average SSC.

      16. Experimental results for a prototype 3-D acoustic imaging system using an ultra-sparse planar array

        NASA Astrophysics Data System (ADS)

        Impagliazzo, John M.; Chiang, Alice M.; Broadstone, Steven R.

        2002-11-01

        A handheld high resolution sonar has been under development to provide Navy Divers with a 3-D acoustic imaging system for mine reconnaissance. An ultra-sparse planar array, consisting of 121 1 mm x1 mm, 2 MHz elements, was fabricated to provide 3-D acoustic images. The array was 10 cm x10 cm. A full array at this frequency with elements at half-wavelength spacing would consist of 16384 elements. The first phase of testing of the planar array was completed in September 2001 with the characterization of the array in the NUWC Acoustic Test Facility (ATF). The center frequency was 2 MHz with a 667 kHz bandwidth. A system-level technology demonstration will be conducted in July 2002 with a real-time beamformer and near real-time 3-D imaging software. The demonstration phase consists of imaging simple targets at a range of 3 m in the ATF. Experimental results obtained will be reported on. [Work supported by the Defense Applied Research Project Agency, Advance Technology Office, Dr. Theo Kooij, Program Manager.

      17. Measuring the parameters of sea-surface roughness by underwater acoustic systems: discussion of the device concept

        NASA Astrophysics Data System (ADS)

        Karaev, V. Yu.; Kanevsky, M. B.; Meshkov, E. M.

        2011-02-01

        We consider the concept of an underwater acoustic wave gauge designed to measure statistical characteristics of sea-surface roughness. It is proposed to be based on a centimeter-wave underwater sonar sending probing signals vertically upwards. It is shown that the use of three antennas in such a system is sufficient to measure all statistical second-order moments of sea roughness which is large-scale compared with the acoustic-radiation wavelength. This method can be used for the first time to measure the sea wave parameters which determine the characteristics of the reflected radar signals. The proposed acoustic wave gauge can be used as an independent measuring device, as well as an additional underwater unit of a conventional sea buoy. This will allow one to increase the amount of information about surface waves, which is received from the buoy, at a minimal cost and will make it possible to calibrate new remote sounding systems capable of measuring the variance of sea-surface slopes.

      18. Doppler effect reduction based on time-domain interpolation resampling for wayside acoustic defective bearing detector system

        NASA Astrophysics Data System (ADS)

        Liu, Fang; He, Qingbo; Kong, Fanrang; Liu, Yongbin

        2014-06-01

        In the wayside Acoustic Defective Bearing Detector (ADBD) system, the recorded acoustic signal will be severely distorted by the Doppler effect because of the high moving speed of the railway vehicle, which is a barrier that would badly reduce the effectiveness of online defect detection. This paper proposes a simple and effective method, called time-domain interpolation resampling (TIR), to remove the Doppler effect embedded in the acoustic signal. The TIR is conducted in three steps. First, the time vector for resampling is calculated according to the kinematic analysis. Second, the amplitude of the distorted signal is demodulated. Third, the distorted signal is re-sampled using spline interpolation. In this method, both the spectrum structure and the amplitudes of the distorted signal can be restored. The effectiveness of TIR is verified by means of simulation studies and train roller bearing experiments with various types of defects. It is also compared to an existing Doppler effect reduction method that is based on the instantaneous frequency estimation using Hilbert transform. Results indicate that the proposed TIR method has the superior performance in removing the Doppler effect, and can be well implemented to Doppler effect reduction for the ADBD system.

      19. High-intensity acoustics for military nonlethal applications: a lack of useful systems.

        PubMed

        Jauchem, James R; Cook, Michael C

        2007-02-01

        There have been many previous claims of nonlethal acoustic weapon effects, mostly in the popular rather than the scientific literature. Anecdotal reports of extraordinary effects can make meaningful assessment and review of this area very difficult. Acoustics research has shown that the nonlethal weapon capabilities of audible sound generators have been grossly overstated. Although high-intensity infrasound significantly disrupted animal behavior in some experiments, the generation of such energy in a volume large enough to be of practical use is unlikely because of basic physical principles. On the basis of experimentation completed to date at a number of institutions, it seems unlikely that high-intensity acoustic energy in the audible, infrasonic, or low-frequency range can provide a device suitable for use as a nonlethal weapon. PMID:17357774

      20. Absence of localized acoustic waves in a scale-free correlated random system.

        PubMed

        Costa, A E B; de Moura, F A B F

        2011-02-16

        We numerically study the propagation of acoustic waves in a one-dimensional medium with a scale-free long-range correlated elasticity distribution. The random elasticity distribution is assumed to have a power spectrum S(k) ∼ 1/k(α). By using a transfer-matrix method we solve the discrete version of the scalar wave equation and compute the localization length. In addition, we apply a second-order finite-difference method for both the time and spatial variables and study the nature of the waves that propagate in the chain. Our numerical data indicate the presence of extended acoustic waves for a high degree of correlations. In contrast with local correlations, we numerically demonstrate that scale-free correlations promote a stable phase of free acoustic waves in the thermodynamic limit. PMID:21406919

      1. Fiber Optic Sensor for Acoustic Detection of Partial Discharges in Oil-Paper Insulated Electrical Systems

        PubMed Central

        Posada-Roman, Julio; Garcia-Souto, Jose A.; Rubio-Serrano, Jesus

        2012-01-01

        A fiber optic interferometric sensor with an intrinsic transducer along a length of the fiber is presented for ultrasound measurements of the acoustic emission from partial discharges inside oil-filled power apparatus. The sensor is designed for high sensitivity measurements in a harsh electromagnetic field environment, with wide temperature changes and immersion in oil. It allows enough sensitivity for the application, for which the acoustic pressure is in the range of units of Pa at a frequency of 150 kHz. In addition, the accessibility to the sensing region is guaranteed by immune fiber-optic cables and the optical phase sensor output. The sensor design is a compact and rugged coil of fiber. In addition to a complete calibration, the in-situ results show that two types of partial discharges are measured through their acoustic emissions with the sensor immersed in oil. PMID:22666058

      2. Liquid Rocket Booster (LRB) for the Space Transportation System (STS) systems study. Appendix B: Liquid rocket booster acoustic and thermal environments

        NASA Technical Reports Server (NTRS)

        1989-01-01

        The ascent thermal environment and propulsion acoustic sources for the Martin-Marietta Corporation designed Liquid Rocket Boosters (LRB) to be used with the Space Shuttle Orbiter and External Tank are described. Two designs were proposed: one using a pump-fed propulsion system and the other using a pressure-fed propulsion system. Both designs use LOX/RP-1 propellants, but differences in performance of the two propulsion systems produce significant differences in the proposed stage geometries, exhaust plumes, and resulting environments. The general characteristics of the two designs which are significant for environmental predictions are described. The methods of analysis and predictions for environments in acoustics, aerodynamic heating, and base heating (from exhaust plume effects) are also described. The acoustic section will compare the proposed exhaust plumes with the current SRB from the standpoint of acoustics and ignition overpressure. The sections on thermal environments will provide details of the LRB heating rates and indications of possible changes in the Orbiter and ET environments as a result of the change from SRBs to LRBs.

      3. A high-temperature acoustic-electric system for power delivery and data communication through thick metallic barriers

        NASA Astrophysics Data System (ADS)

        Lawry, T. J.; Wilt, K. R.; Roa-Prada, S.; Ashdown, J. D.; Saulnier, G. J.; Scarton, H. A.; Das, P. K.; Gavens, A. J.

        2011-06-01

        In many sensing applications that monitor extreme environmental conditions within sealed metallic vessels, penetrating vessel walls in order to feed through power and data cables is impractical, as this may compromise a vessels structural integrity and its environmental isolation. Frequent servicing of sensing equipment within these environments is costly, so the use of batteries is strongly undesired and power harvesting techniques are preferred. Traditional electromagnetic power delivery and communication techniques, however, are highly ineffective in these applications, due to Faraday shielding effects from the metallic vessel walls. A viable, non-destructive alternative is to use piezoelectric materials to transmit power through thick metallic barriers acoustically. We present critical elements of a high-temperature battery-less sensor system prototype, including power harvesting, voltage regulation, and data communication circuitry able to operate up to 260°C. Power transmission is achieved by coaxially aligning a pair of high-temperature piezoelectric transducers on opposite sides of a thick steel barrier. Continuous-wave excitation of the outside transducer creates an acoustic beam that is captured by the opposite transducer, forming an acoustic-electric link for power harvesting circuitry. Simultaneously, sensor data can be transmitted out of the high-temperature environment by switching the electrical impedance placed across the leads of the inside transducer, creating a reflection-based amplitude modulated signal on the outside transducer. Transducer housing, loading, and alternatives for acoustic couplants are discussed. Measurement results are presented, and it was found that the system can harvest up to 1 watt of power and communicate sensor data up to 50 kbps, while operating at 260°C.

      4. Active Response Gravity Offload System

        NASA Technical Reports Server (NTRS)

        Valle, Paul; Dungan, Larry; Cunningham, Thomas; Lieberman, Asher; Poncia, Dina

        2011-01-01

        The Active Response Gravity Offload System (ARGOS) provides the ability to simulate with one system the gravity effect of planets, moons, comets, asteroids, and microgravity, where the gravity is less than Earth fs gravity. The system works by providing a constant force offload through an overhead hoist system and horizontal motion through a rail and trolley system. The facility covers a 20 by 40-ft (approximately equals 6.1 by 12.2m) horizontal area with 15 ft (approximately equals4.6 m) of lifting vertical range.

      5. Wind Turbine Generator System Acoustic Noise Test Report for the ARE 442 Wind Turbine

        SciTech Connect

        Huskey, A.; van Dam, J.

        2010-11-01

        This test was conducted on the ARE 442 as part of the U.S. Department of Energy's (DOE's) Independent Testing project. This project was established to help reduce the barriers of wind energy expansion by providing independent testing results for small turbines. In total, five turbines are being tested at the National Wind Technology Center (NWTC) as a part of this project. Acoustic noise testing is one of up to five tests that may be performed on the turbines, including duration, safety and function, power performance, and power quality tests. The acoustic noise test was conducted to the IEC 61400-11 Edition 2.1.

      6. Theory and investigation of acoustic multiple-input multiple-output systems based on spherical arrays in a room.

        PubMed

        Morgenstern, Hai; Rafaely, Boaz; Zotter, Franz

        2015-11-01

        Spatial attributes of room acoustics have been widely studied using microphone and loudspeaker arrays. However, systems that combine both arrays, referred to as multiple-input multiple-output (MIMO) systems, have only been studied to a limited degree in this context. These systems can potentially provide a powerful tool for room acoustics analysis due to the ability to simultaneously control both arrays. This paper offers a theoretical framework for the spatial analysis of enclosed sound fields using a MIMO system comprising spherical loudspeaker and microphone arrays. A system transfer function is formulated in matrix form for free-field conditions, and its properties are studied using tools from linear algebra. The system is shown to have unit-rank, regardless of the array types, and its singular vectors are related to the directions of arrival and radiation at the microphone and loudspeaker arrays, respectively. The formulation is then generalized to apply to rooms, using an image source method. In this case, the rank of the system is related to the number of significant reflections. The paper ends with simulation studies, which support the developed theory, and with an extensive reflection analysis of a room impulse response, using the platform of a MIMO system. PMID:26627773

      7. Acoustic transducer

        DOEpatents

        Drumheller, Douglas S.

        2000-01-01

        An active acoustic transducer tool for use down-hole applications. The tool includes a single cylindrical mandrel including a shoulder defining the boundary of a narrowed portion over which is placed a sandwich-style piezoelectric tranducer assembly. The piezoelectric transducer assembly is prestressed by being placed in a thermal interference fit between the shoulder of the mandrel and the base of an anvil which is likewise positioned over the narrower portion of the mandrel. In the preferred embodiment, assembly of the tool is accomplished using a hydraulic jack to stretch the mandrel prior to emplacement of the cylindrical sandwich-style piezoelectric transducer assembly and anvil. After those elements are positioned and secured, the stretched mandrel is allowed to return substantially to its original (pre-stretch) dimensions with the result that the piezoelectric transducer elements are compressed between the anvil and the shoulder of the mandrel.

      8. Experimental Study to Produce Multiple Focal Points of Acoustic Field for Active Path Selection of Microbubbles through Multi-bifurcation

        NASA Astrophysics Data System (ADS)

        Koda, Ren; Koido, Jun; Ito, Takumi; Mochizuki, Takashi; Masuda, Kohji; Ikeda, Seiichi; Arai, Fumihito; Miyamoto, Yoshitaka; Chiba, Toshio

        2013-07-01

        We previously reported our attempt to propel microbubbles in a flow by a primary Bjerknes force, which is a physical phenomenon where an acoustic wave pushes an obstacle along its direction of propagation. However, when ultrasound was emitted from the surface of the body, controlling bubbles in an against-flow was necessary. It is unpractical to use multiple transducers to produce the same number of focal points because single-element transducers cannot produce more than two focal points. In this study, we introduced a complex artificial blood vessel according to a capillary model and a two-dimensional (2D) array transducer to produce multiple focal points for the active control of microbubbles in an against-flow. From the results, about 15% more microbubbles were led to the desired path with multiple focal points of ultrasound relative to the no-emission case.

      9. Topological Acoustics

        NASA Astrophysics Data System (ADS)

        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.

      10. Topological acoustics.

        PubMed

        Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

        2015-03-20

        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. PMID:25839273

      11. A custom acoustic emission monitoring system for harsh environments: application to freezing-induced damage in alpine rock-walls

        NASA Astrophysics Data System (ADS)

        Girard, L.; Beutel, J.; Gruber, S.; Hunziker, J.; Lim, R.; Weber, S.

        2012-06-01

        We present a custom acoustic emission (AE) monitoring system designed to perform long-term measurements on high-alpine rock-walls. AE monitoring is a common technique for characterizing damage evolution in solid materials. The system is based on a two-channel AE sensor node (AE-node) integrated into a Wireless Sensor Network (WSN) customized for operation in harsh environments. This wireless architecture offers flexibility in the deployment of AE-nodes at any position of the rock-wall that needs to be monitored, within a range of a few hundred meters from a core station connected to the internet. The system achieves near real-time data delivery and allows the user to remotely control the AE detection threshold. In order to protect AE sensors and capture acoustic signals from specific depths of the rock-wall, a special casing was developed. The monitoring system is completed by two probes that measure rock temperature and liquid water content, both probes being also integrated into the WSN. We report a first deployment of the monitoring system on a rock-wall at Jungfraujoch, 3500 m a.s.l., Switzerland. While this first deployment of the monitoring system aims to support fundamental research on processes that damage rock under cold climate, the system could serve a number of other applications, including rock-fall hazard surveillance or structural monitoring of concrete structures.

      12. A custom acoustic emission monitoring system for harsh environments: application to freezing-induced damage in alpine rock walls

        NASA Astrophysics Data System (ADS)

        Girard, L.; Beutel, J.; Gruber, S.; Hunziker, J.; Lim, R.; Weber, S.

        2012-11-01

        We present a custom acoustic emission (AE) monitoring system designed to perform long-term measurements on high-alpine rock walls. AE monitoring is a common technique for characterizing damage evolution in solid materials. The system is based on a two-channel AE sensor node (AE-node) integrated into a wireless sensor network (WSN) customized for operation in harsh environments. This wireless architecture offers flexibility in the deployment of AE-nodes at any position of the rock wall that needs to be monitored, within a range of a few hundred meters from a core station connected to the internet. The system achieves near real-time data delivery and allows the user to remotely control the AE detection threshold. In order to protect AE sensors and capture acoustic signals from specific depths of the rock wall, a special casing was developed. The monitoring system is completed by two probes that measure rock temperature and liquid water content, both probes being also integrated into the WSN. We report a first deployment of the monitoring system on a rock wall at Jungfraujoch, 3500 m a.s.l., Switzerland. While this first deployment of the monitoring system aims to support fundamental research on processes that damage rock under cold climate, the system could serve a number of other applications, including rock fall hazard surveillance or structural monitoring of concrete structures.

      13. ACTIVELY CONTROLLED VORTEX DISPOSAL SYSTEM FOR SLUDGE WASTES

        EPA Science Inventory

        The development of an advanced sludge treatment concept is under way for applications to sludge wastes. The concept integrates primary treatment of sludge in an advanced vortex containment combustor (VCC) with subsequent post treatment in an actively controlled acoustic afterburn...

      14. ACTIVELY CONTROLLED VORTEX DISPOSAL SYSTEM FOR SLUDGE WASTES

        EPA Science Inventory

        The development of an advanced sludge treatment concept is underway for applications to sludge wastes. The concept integrates primary treatment of sludge in an advanced vortex containment combustor (VCC) with subsequent post treatment in an actively controlled acoustic afterburne...

      15. Acoustic rotation control

        NASA Technical Reports Server (NTRS)

        Elleman, D. D.; Croonquist, A. P.; Wang, T. G. (Inventor)

        1983-01-01

        A system is described for acoustically controlled rotation of a levitated object, which avoids deformation of a levitated liquid object. Acoustic waves of the same wavelength are directed along perpendicular directions across the object, and with the relative phases of the acoustic waves repeatedly switched so that one wave alternately leads and lags the other by 90 deg. The amount of torque for rotating the object, and the direction of rotation, are controlled by controlling the proportion of time one wave leads the other and selecting which wave leads the other most of the time.

      16. Acoustic mapping velocimetry

        NASA Astrophysics Data System (ADS)

        Muste, M.; Baranya, S.; Tsubaki, R.; Kim, D.; Ho, H.; Tsai, H.; Law, D.

        2016-05-01

        Knowledge of sediment dynamics in rivers is of great importance for various practical purposes. Despite its high relevance in riverine environment processes, the monitoring of sediment rates remains a major and challenging task for both suspended and bed load estimation. While the measurement of suspended load is currently an active area of testing with nonintrusive technologies (optical and acoustic), bed load measurement does not mark a similar progress. This paper describes an innovative combination of measurement techniques and analysis protocols that establishes the proof-of-concept for a promising technique, labeled herein Acoustic Mapping Velocimetry (AMV). The technique estimates bed load rates in rivers developing bed forms using a nonintrusive measurements approach. The raw information for AMV is collected with acoustic multibeam technology that in turn provides maps of the bathymetry over longitudinal swaths. As long as the acoustic maps can be acquired relatively quickly and the repetition rate for the mapping is commensurate with the movement of the bed forms, successive acoustic maps capture the progression of the bed form movement. Two-dimensional velocity maps associated with the bed form migration are obtained by implementing algorithms typically used in particle image velocimetry to acoustic maps converted in gray-level images. Furthermore, use of the obtained acoustic and velocity maps in conjunction with analytical formulations (e.g., Exner equation) enables estimation of multidirectional bed load rates over the whole imaged area. This paper presents a validation study of the AMV technique using a set of laboratory experiments.

      17. Quantitative and Descriptive Comparison of Four Acoustic Analysis Systems: Vowel Measurements

        ERIC Educational Resources Information Center

        Burris, Carlyn; Vorperian, Houri K.; Fourakis, Marios; Kent, Ray D.; Bolt, Daniel M.

        2014-01-01

        Purpose: This study examines accuracy and comparability of 4 trademarked acoustic analysis software packages (AASPs): Praat, WaveSurfer, TF32, and CSL by using synthesized and natural vowels. Features of AASPs are also described. Method: Synthesized and natural vowels were analyzed using each of the AASP's default settings to secure 9…

      18. The Effect of Intertalker Variations on Acoustic-Perceptual Mapping in Cantonese and Mandarin Tone Systems

        ERIC Educational Resources Information Center

        Peng, Gang; Zhang, Caicai; Zheng, Hong-Ying; Minett, James W.; Wang, William S.-Y.

        2012-01-01

        Purpose: This study investigates the impact of intertalker variations on the process of mapping acoustic variations on tone categories in two different tone languages. Method: Pitch stimuli manipulated from four voice ranges were presented in isolation through a blocked-talker design. Listeners were instructed to identify the stimuli that they…

      19. Hover and forward flight acoustics and performance of a small-scale helicopter rotor system

        NASA Technical Reports Server (NTRS)

        Kitaplioglu, C.; Shinoda, P.

        1985-01-01

        A 2.1-m diam., 1/6-scale model helicopter main rotor was tested in hover in the test section of the NASA Ames 40- by 80- Foot Wind Tunnel. Subsequently, it was tested in forward flight in the Ames 7- by 10-Foot Wind Tunnel. The primary objective of the tests was to obtain performance and noise data on a small-scale rotor at various thrust coefficients, tip Mach numbers, and, in the later case, various advance ratios, for comparisons with similar existing data on full-scale helicopter rotors. This comparison yielded a preliminary evaluation of the scaling of helicopter rotor performance and acoustic radiation in hover and in forward flight. Correlation between model-scale and full-scale performance and acoustics was quite good in hover. In forward flight, however, there were significant differences in both performance and acoustic characteristics. A secondary objective was to contribute to a data base that will permit the estimation of facility effects on acoustic testing.

      20. A static acoustic signature system for the analysis of dynamic flight information

        NASA Technical Reports Server (NTRS)

        Ramer, D. J.

        1978-01-01

        The Army family of helicopters was analyzed to measure the polar octave band acoustic signature in various modes of flight. A static array of calibrated microphones was used to simultaneously acquire the signature and differential times required to mathematically position the aircraft in space. The signature was then reconstructed, mathematically normalized to a fixed radius around the aircraft.