Science.gov

Sample records for acoustic experiments involving

  1. Nonlinear Acoustic Experiments Involving Landmine Detection: Connections with Mesoscopic Elasticity and Slow Dynamics in Geomaterials

    NASA Astrophysics Data System (ADS)

    Korman, Murray S.; Sabatier, James M.

    2006-05-01

    The vibration interaction between the top-plate of a buried VS 2.2 plastic, anti-tank landmine and the soil above it appears to exhibit similar characteristics to the nonlinear mesoscopic/nanoscale effects that are observed in geomaterials like rocks or granular materials. [J. Acoust. Soc. Am. 116, 3354-3369 (2004)]. When airborne sound at two primary frequencies f1 and f2 (closely spaced near resonance) undergo acoustic-to-seismic coupling, (A/S), interactions with the mine and soil generate combination frequencies | n f1 ± m f2 | which affect the surface vibration velocity. Profiles at f1, f2, f1 -(f2 - f1) and f2 +(f2 - f1) exhibit single peaks whereas other combination frequencies may involve higher order modes. A family of increasing amplitude tuning curves, involving the surface vibration over the landmine, exhibits a linear relationship between the peak particle velocity and corresponding resonant frequency. Subsequent decreasing amplitude tuning curves exhibit hysteresis effects. New experiments for a buried VS 1.6 anti-tank landmine and a "plastic drum head" mine simulant behave similarly. Slow dynamics explains the amplitude difference in tuning curves for first sweeping upward and then downward through resonance, provided the soil modulus drops after periods of high strain. [Support by U.S. Army RDECOM CERDEC, NVESD, Fort Belvoir, VA.

  2. Nonlinear acoustic experiments involving landmine detection: Connections with mesoscopic elasticity and slow dynamics in geomaterials

    NASA Astrophysics Data System (ADS)

    Korman, Murray S.; Fenneman, Douglas J.; Sabatier, James M.

    2004-10-01

    The vibration interaction between the top-plate of a buried VS 1.6 plastic, anti-tank landmine and the soil above it appears to exhibit similar characteristics to the nonlinear mesoscopic/nanoscale effects that are observed in geomaterials like rocks or granular materials. In nonlinear detection schemes, airborne sound at two primary frequencies f1 and f2 (chosen several Hz apart on either side of resonance) undergo acoustic-to-seismic coupling. Interactions with the compliant mine and soil generate combination frequencies that, through scattering, can effect the vibration velocity at the surface. Profiles at f1, f2, f1-(f2-f1) and f2+(f2-f1) exhibit a single peak while profiles at 2f1-(f2-f1), f1+f2 and 2f2+(f2-f1) are attributed to higher order mode shapes. Near resonance (~125 Hz for a mine buried 3.6 cm deep), the bending (softening) of a family of increasing amplitude tuning curves (involving the surface vibration over the landmine) exhibits a linear relationship between the peak particle velocity and corresponding frequency. Subsequent decreasing amplitude tuning curves exhibit hysteresis effects. Slow dynamics explains the amplitude difference in tuning curves for first sweeping upward and then downward through resonance, provided the soil modulus drops after periods of high strain. [Work supported by U.S. Army RDECOM, CERDEC, NVESD, Fort Belvoir, VA.

  3. Nonlinear acoustic experiments involving landmine detection: Connections with mesoscopic elasticity and slow dynamics in geomaterials, Part III

    NASA Astrophysics Data System (ADS)

    Korman, Murray S.; Sabatier, James M.

    2005-09-01

    In nonlinear acoustic detection schemes, airborne sound at two primary tones, f1, f2 (closely spaced near an 80-Hz resonance) excites the soil surface over a buried landmine. Due to soil wave interactions with the landmine, a scattered surface profile can be measured by a geophone. Profiles at f1, f2, f1-(f2-f1) and f2+(f2-f1) exhibit single peaks; those at 2f1-(f2-f1), f1+f2 and 2f2+(f2-f1) involve higher order mode shapes for a VS 2.2 plastic, inert, anti-tank landmine, buried at 3.6 cm in sifted loess soil [J. Acoust. Soc. Am. 116, 3354-3369 (2004)]. Near resonance, the bending (softening) of a family of increasing amplitude tuning curves, involving the vibration over the landmine, exhibits a linear relationship between the peak particle velocity and corresponding frequency. Results are similar to nonlinear mesoscopic/nanoscale effects that are observed in granular solids like Berea sandstone. New experiments show that first sweeping up through resonance and then immediately sweeping back down result in different tuning curve behavior that might be explained by ``slow dynamics'' where an effective modulus reduction persists following periods of high strain. Results are similar to those described by TenCate et al. [Phys. Rev. Lett. 85, 1020-1023 (2000)]. [Work supported by U.S. Army RDECOM CERDEC, NVESD.

  4. Acoustic noise from volcanoes - Theory and experiment

    NASA Technical Reports Server (NTRS)

    Woulff, G.; Mcgetchin, T. R.

    1976-01-01

    The paper discusses some theoretical aspects of acoustic investigation of volcanoes and describes a field experiment involving the recording, analysis, and interpretation of acoustic radiation from energetic fumaroles at Volcan Acatenango, Guatemala, during mid-January 1973. Particular attention is given to deriving information about the flow velocity of the erupting medium from acoustics as a means to study eruption dynamics. Theoretical considerations suggest that acoustic power radiated during gaseous volcanic eruptions may be related to gas exit velocity according to appropriate power laws. Eruption acoustics proves useful as a means of quantitative monitoring of volcanic activity.

  5. Experiments on the Acoustics of Whistling.

    ERIC Educational Resources Information Center

    Shadle, Christine H.

    1983-01-01

    The acoustics of speech production allows the prediction of resonances for a given vocal tract configuration. Combining these predictions with aerodynamic theory developed for mechanical whistles makes theories about human whistling more complete. Several experiments involving human whistling are reported which support the theory and indicate new…

  6. Joint Acoustic Propagation Experiment (JAPE)

    NASA Technical Reports Server (NTRS)

    Carnes, Benny L.; Olsen, Robert O.; Kennedy, Bruce W.

    1993-01-01

    The Joint Acoustic Propagation Experiment (JAPE), performed under the auspices of NATO and the Acoustics Working Group, was conducted at White Sands Missile Range, New Mexico, USA, during the period 11-28 Jul. 1991. JAPE consisted of 220 trials using various acoustic sources including speakers, propane cannon, various types of military vehicles, helicopters, a 155mm howitzer, and static high explosives. Of primary importance to the performance of these tests was the intensive characterization of the atmosphere before and during the trials. Because of the wide range of interests on the part of the participants, JAPE was organized in such a manner to provide a broad cross section of test configurations. These included short and long range propagation from fixed and moving vehicles, terrain masking, and vehicle detection. A number of independent trials were also performed by individual participating agencies using the assets available during JAPE. These tests, while not documented in this report, provided substantial and important data to those groups. Perhaps the most significant feature of JAPE is the establishment of a permanent data base which can be used by not only the participants but by others interested in acoustics. A follow-on test was performed by NASA LaRC during the period 19-29 Aug. 1991 at the same location. These trials consisted of 59 overflights of supersonic aircraft in order to establish the relationship between atmospheric turbulence and the received sonic boom energy at the surface.

  7. Acoustic scattering in flexible waveguide involving step discontinuity.

    PubMed

    Afzal, Muhammad; Nawaz, Rab; Ayub, Muhammad; Wahab, Abdul

    2014-01-01

    In this paper, the propagation and scattering of acoustic waves in a flexible wave-guide involving step discontinuity at an interface is considered. The emerging boundary value problem is non-Sturm-Liouville and is solved by employing a hybrid mode-matching technique. The physical scattering process and attenuation of duct modes versus frequency regime and change of height is studied. Moreover, the mode-matching solution is validated through a series of numerical experiments by testifying the power conservation identity and matching interface conditions. PMID:25084019

  8. Acoustic emission sensor radiation damage threshold experiment

    SciTech Connect

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

    1994-09-01

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

  9. The RAP experiment: Acoustic Detection of Particles

    NASA Astrophysics Data System (ADS)

    Bassan, M.; Buonomo, B.; Cavallari, G.; Coccia, E.; D'Antonio, S.; Delle Monache, G.; Di Gioacchino, D.; Fafone, V.; Ligi, C.; Marini, A.; Mazzitelli, G.; Modestino, G.; Pizzella, G.; Quintieri, L.; Roccella, S.; Rocchi, A.; Ronga, F.; Tripodi, P.; Valente, P.

    2007-10-01

    The RAP experiment is based on the acoustic detection of high energy particles by cylindrical bars. In fact, the interacting particles warm up the material around their track causing a local thermal expansion that, being prevented by the rest of the material, causes a local impulse of pressure. Consequently the bar starts to vibrate and the amplitude of the oscillation is proportional to the energy released. The RAP experiment has the aim to investigate the mechanical excitation of cylindrical bars caused by impinging particles depending on the conducting status of the material of which the detector is made. In particular physical phenomena related to the superconductivity state could be involved in such a way to enhance the conversion efficiency of the particle energy into mechanical vibrations. Essentially, two materials have been tested: aluminum alloy (Al5056) and niobium. In this report we report the measurements obtained for a niobium bar from room temperature down to 4K, below the transition temperature, and those obtained for an Al5056 bar above the transition (from 4 to 293 K).

  10. Joint Acoustic Propagation Experiment (JAPE-91) Workshop

    NASA Technical Reports Server (NTRS)

    Willshire, William L., Jr. (Compiler); Chestnutt, David (Compiler)

    1993-01-01

    The Joint Acoustic Propagation Experiment (JAPE), was conducted at the White Sands Missile Range, New Mexico, USA, during the period 11-28 Jul. 1991. JAPE consisted of various short and long range propagation experiments using various acoustic sources including speakers, propane cannons, helicopters, a 155 mm howitzer, and static high explosives. Of primary importance to the performance of theses tests was the extensive characterization of the atmosphere during these tests. This atmospheric characterization included turbulence measurements. A workshop to disseminate the results of JAPE-91 was held in Hampton, VA, on 28 Apr. 1993. This report is a compilation of the presentations made at the workshop along with a list of attendees and the agenda.

  11. Vehicular sources in acoustic propagation experiments

    NASA Technical Reports Server (NTRS)

    Prado, Gervasio; Fitzgerald, James; Arruda, Anthony; Parides, George

    1990-01-01

    One of the most important uses of acoustic propagation models lies in the area of detection and tracking of vehicles. Propagation models are used to compute transmission losses in performance prediction models and to analyze the results of past experiments. Vehicles can also provide the means for cost effective experiments to measure acoustic propagation conditions over significant ranges. In order to properly correlate the information provided by the experimental data and the propagation models, the following issues must be taken into consideration: the phenomenology of the vehicle noise sources must be understood and characterized; the vehicle's location or 'ground truth' must be accurately reproduced and synchronized with the acoustic data; and sufficient meteorological data must be collected to support the requirements of the propagation models. The experimental procedures and instrumentation needed to carry out propagation experiments are discussed. Illustrative results are presented for two cases. First, a helicopter was used to measure propagation losses at a range of 1 to 10 Km. Second, a heavy diesel-powered vehicle was used to measure propagation losses in the 300 to 2200 m range.

  12. Radiosurgery for acoustic neurinomas: Early experience

    SciTech Connect

    Linskey, M.E.; Lunsford, L.D.; Flickinger, J.C. )

    1990-05-01

    We reviewed our early experience with the first 26 patients with acoustic neurinomas (21 unilateral, 5 bilateral) treated by stereotactic radiosurgery using the first North American 201-source cobalt-60 gamma knife. Follow-up ranged from 6 to 19 months (median, 13 months). Serial postoperative imaging showed either a decrease in tumor size (11 patients) or growth arrest (15 patients). Loss of central contrast enhancement was a characteristic change (18 patients). Seven patients had good or serviceable hearing preoperatively. In all 7 the preoperative hearing status was retained immediately after radiosurgery. At follow-up, 3 had preserved hearing, 1 had reduced hearing, and 3 had lost all hearing in the treated ear. Hearing in 1 patient that was nonserviceable preoperatively later improved to a serviceable hearing level. Delayed facial paresis developed in 6 patients, and delayed trigeminal sensory loss developed in 7 patients, none of whom had significant deficits before radiosurgery. Both facial and trigeminal deficits tended to improve within 3 to 6 months of onset with excellent recovery anticipated. Lower cranial nerve dysfunction was not observed. All 26 patients remain at their preoperative employment or functional status. At present, stereotactic radiosurgery is an alternative treatment for acoustic neurinomas in patients who are elderly, have significant concomitant medical problems, have a tumor in their only hearing ear, have bilateral acoustic neurinomas, refuse microsurgical excision, or have recurrent tumor despite surgical resection. Although longer and more extensive follow-up is required, the control of tumor growth and the acceptable rate of complications in this early experience testifies to the future expanding role of this technique in the management of selected acoustic neurinomas.

  13. The North Pacific Acoustic Laboratory deep-water acoustic propagation experiments in the Philippine Sea.

    PubMed

    Worcester, Peter F; Dzieciuch, Matthew A; Mercer, James A; Andrew, Rex K; Dushaw, Brian D; Baggeroer, Arthur B; Heaney, Kevin D; D'Spain, Gerald L; Colosi, John A; Stephen, Ralph A; Kemp, John N; Howe, Bruce M; Van Uffelen, Lora J; Wage, Kathleen E

    2013-10-01

    A series of experiments conducted in the Philippine Sea during 2009-2011 investigated deep-water acoustic propagation and ambient noise in this oceanographically and geologically complex region: (i) the 2009 North Pacific Acoustic Laboratory (NPAL) Pilot Study/Engineering Test, (ii) the 2010-2011 NPAL Philippine Sea Experiment, and (iii) the Ocean Bottom Seismometer Augmentation of the 2010-2011 NPAL Philippine Sea Experiment. The experimental goals included (a) understanding the impacts of fronts, eddies, and internal tides on acoustic propagation, (b) determining whether acoustic methods, together with other measurements and ocean modeling, can yield estimates of the time-evolving ocean state useful for making improved acoustic predictions, (c) improving our understanding of the physics of scattering by internal waves and spice, (d) characterizing the depth dependence and temporal variability of ambient noise, and (e) understanding the relationship between the acoustic field in the water column and the seismic field in the seafloor. In these experiments, moored and ship-suspended low-frequency acoustic sources transmitted to a newly developed distributed vertical line array receiver capable of spanning the water column in the deep ocean. The acoustic transmissions and ambient noise were also recorded by a towed hydrophone array, by acoustic Seagliders, and by ocean bottom seismometers. PMID:24116529

  14. 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…

  15. Ion Acoustic Waves, A High School Plasma Experiment

    NASA Astrophysics Data System (ADS)

    Buck, R.; Wise, J.; Gibson, N.; Buck, M.; Gekelman, W.; Wetzel, E.; Wetzel, C.; Moynihan, C.

    2001-10-01

    Over the last three the Los Angeles Physics Teachers Alliance Group (LAPTAG) has built a plasma device and designed experiments for high school students to learn about plasma properties and behavior. One of the first experiments performed by small student groups (two to three students at a time) is to create ion acoustic wave tonebursts in an Argon plasma, measure the wavelength and frequency of the wave and thereby calculate the velocity of the wave. A grid antenna immersed in the plasma, which is pulsed by a function generator, creates the waves. Measurements are made using a Langmuir probe and read out on a digital oscilloscope. From this information students calculate values such as the temperature of the plasma, the plasma density and percent ionization of the plasma. In order to do these experiments students must understand what plasma is, how plasma can be created using a helicon source, how to use an oscilloscope and many other aspects of the plasma chamber involved in the experiment. Other experiments are currently being done on the device and still others are being designed. For more information visit the LAPTAG website (http://coke.physics.ucla.edu/laptag).

  16. Acoustical experiment of yogurt fermentation process.

    PubMed

    Ogasawara, H; Mizutani, K; Ohbuchi, T; Nakamura, T

    2006-12-22

    One of the important factors through food manufacturing is hygienic management. Thus, food manufactures prove their hygienic activities by taking certifications like a Hazard Analysis and Critical Control Point (HACCP). This concept also applies to food monitoring. Acoustical measurements have advantage for other measurement in food monitoring because they make it possible to measure with noncontact and nondestructive. We tried to monitor lactic fermentation of yogurt by a probing sensor using a pair of acoustic transducers. Temperature of the solution changes by the reaction heat of fermentation. Consequently the sound velocity propagated through the solution also changes depending on the temperature. At the same time, the solution change its phase from liquid to gel. The transducers usage in the solution indicates the change of the temperature as the change of the phase difference between two transducers. The acoustic method has advantages of nondestructive measurement that reduces contamination of food product by measuring instrument. The sensor was inserted into milk with lactic acid bacterial stain of 19 degrees C and monitored phase retardation of propagated acoustic wave and its temperature with thermocouples in the mild. The monitoring result of fermentation from milk to Caspian Sea yogurt by the acoustic transducers with the frequency of 3.7 MHz started to show gradient change in temperature caused by reaction heat of fermentation but stop the gradient change at the end although the temperature still change. The gradient change stopped its change because of phase change from liquid to gel. The present method will be able to measure indirectly by setting transducers outside of the measuring object. This noncontact sensing method will have great advantage of reduces risk of food contamination from measuring instrument because the measurement probes are set out of fermentation reactor or food containers. Our proposed method will contribute to the

  17. Analysis of passive acoustic ranging of helicopters from the joint acoustic propagation experiment

    NASA Technical Reports Server (NTRS)

    Carnes, Benny L.; Morgan, John C.

    1993-01-01

    For more than twenty years, personnel of the U.S.A.E. Waterways Experiment Station (WES) have been performing research dealing with the application of sensors for detection of military targets. The WES research has included the use of seismic, acoustic, magnetic, and other sensors to detect, track, and classify military ground targets. Most of the WES research has been oriented toward the employment of such sensors in a passive mode. Techniques for passive detection are of particular interest in the Army because of the advantages over active detection. Passive detection methods are not susceptible to interception, detection, jamming, or location of the source by the threat. A decided advantage for using acoustic and seismic sensors for detection in tactical situations is the non-line-of-sight capability; i.e., detection of low flying helicopters at long distances without visual contact. This study was conducted to analyze the passive acoustic ranging (PAR) concept using a more extensive data set from the Joint Acoustic Propagation Experiment (JAPE).

  18. 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.

  19. Acoustic experience shapes female mate choice in field crickets

    PubMed Central

    Bailey, Nathan W; Zuk, Marlene

    2008-01-01

    Female choice can drive the evolution of extravagant male traits. In invertebrates, the influence of prior social experience on female choice has only recently been considered. To better understand the evolutionary implications of experience-mediated plasticity in female choice, we investigated the effect of acoustic experience during rearing on female responsiveness to male song in the field cricket Teleogryllus oceanicus. Acoustic experience has unique biological relevance in this species: a morphological mutation has rendered over 90 per cent of males on the Hawaiian island of Kauai silent in fewer than 20 generations, impeding females' abilities to locate potential mates. Females reared in silent conditions mimicking Kauai were less discriminating of male calling song and more responsive to playbacks, compared with females that experienced song during rearing. Our results to our knowledge, are the first demonstration of long-term effects of acoustic experience in an arthropod, and suggest that female T. oceanicus may be able to compensate for the reduced availability of long-range male sexual signals by increasing their responsiveness to the few remaining signallers. Understanding the adaptive significance of experience-mediated plasticity in female choice provides insight into processes that facilitate rapid evolutionary change and shape sexual selection pressure in natural populations. PMID:18700205

  20. Acoustic experience shapes female mate choice in field crickets.

    PubMed

    Bailey, Nathan W; Zuk, Marlene

    2008-11-22

    Female choice can drive the evolution of extravagant male traits. In invertebrates, the influence of prior social experience on female choice has only recently been considered. To better understand the evolutionary implications of experience-mediated plasticity in female choice, we investigated the effect of acoustic experience during rearing on female responsiveness to male song in the field cricket Teleogryllus oceanicus. Acoustic experience has unique biological relevance in this species: a morphological mutation has rendered over 90 per cent of males on the Hawaiian island of Kauai silent in fewer than 20 generations, impeding females' abilities to locate potential mates. Females reared in silent conditions mimicking Kauai were less discriminating of male calling song and more responsive to playbacks, compared with females that experienced song during rearing. Our results to our knowledge, are the first demonstration of long-term effects of acoustic experience in an arthropod, and suggest that female T. oceanicus may be able to compensate for the reduced availability of long-range male sexual signals by increasing their responsiveness to the few remaining signallers. Understanding the adaptive significance of experience-mediated plasticity in female choice provides insight into processes that facilitate rapid evolutionary change and shape sexual selection pressure in natural populations. PMID:18700205

  1. Acoustic containerless processing module for material research. [Space Shuttle experiments

    NASA Technical Reports Server (NTRS)

    Lagomarsini, G. C.; Wang, T.

    1979-01-01

    In the Shuttle space processing program, the melt is formed within a container without physically contacting the container walls. The present paper deals with a high-temperature acoustic containerless processing module currently under development for early OSTA Shuttle flights. The manipulation capabilities of this module are expected to meet the requirements of a wide variety of experiments. Some novel techniques in optics and control are discussed.

  2. Ion acoustic envelope solitons in explosive ionospheric experiments

    NASA Astrophysics Data System (ADS)

    Kovaleva, I. Kh.

    2008-01-01

    The conditions are studied under which stable ion acoustic envelope solitons propagating perpendicular to the magnetic field lines can exist in the ionospheric plasma. The amplitudes, frequencies, and lengths of the waves are determined. The results obtained are compared with the experimental data. It is suggested that such solitons play an important role in both the formation of an ionization front and its motion across the magnetic field and also give rise to a fluctuation precursor in explosive ionospheric experiments.

  3. Ion acoustic envelope solitons in explosive ionospheric experiments

    SciTech Connect

    Kovaleva, I. Kh.

    2008-01-15

    The conditions are studied under which stable ion acoustic envelope solitons propagating perpendicular to the magnetic field lines can exist in the ionospheric plasma. The amplitudes, frequencies, and lengths of the waves are determined. The results obtained are compared with the experimental data. It is suggested that such solitons play an important role in both the formation of an ionization front and its motion across the magnetic field and also give rise to a fluctuation precursor in explosive ionospheric experiments.

  4. Acoustic emissions in rock deformation experiments under micro-CT

    NASA Astrophysics Data System (ADS)

    Tisato, Nicola; Goodfellow, Sebastian D.; Moulas, Evangelos; Di Toro, Giulio; Young, Paul; Grasselli, Giovanni

    2016-04-01

    The study of acoustic emissions (AE) generated by rocks undergoing deformation has become, in the last decades, one of the most powerful tools for boosting our understanding of the mechanisms which are responsible for rock failures. AE are elastic waves emitted by the local failure of micro- or milli-metric portions of the tested specimen. At the same time, X-ray micro computed tomography (micro-CT) has become an affordable, reliable and powerful tool for imaging the internal structure of rock samples. In particular, micro-CT coupled with a deformation apparatus offers the unique opportunity for observing, without perturbing, the sample while the deformation and the formation of internal structures, such as shear bands, is ongoing. Here we present some preliminary results gathered with an innovative apparatus formed by the X-ray transparent pressure vessel called ERDμ equipped with AE sensors, an AE acquisition system and a micro-CT apparatus available at the University of Toronto. The experiment was performed on a 12 mm diameter 36 mm long porous glass sample which was cut on a 60 deg inclined plane (i.e. saw-cut sample). Etna basaltic sand with size ~1 mm was placed between the two inclined faces forming an inclined fault zone with ~2 mm thickness. The sample assembly was jacketed with a polyefin shrink tube and two AE sensors were glued onto the glass samples above and below the fault zone. The sample was then enclosed in the pressure vessel and confined with compressed air up to 3 MPa. A third AE sensor was placed outside the vessel. The sample was saturated with water and AE were generated by varying the fluid and confining pressure or the vertical force, causing deformations concentrated in the fault zone. Mechanical data and AE traces were collected throughout the entire experiment which lasted ~24 hours. At the same time multiple micro-CT 3D datasets and 2D movie-radiographies were collected, allowing the 3D reconstruction of the deformed sample at

  5. Adaptive ocean acoustic processing for a shallow ocean experiment

    SciTech Connect

    Candy, J.V.; Sullivan, E.J.

    1995-07-19

    A model-based approach is developed to solve an adaptive ocean acoustic signal processing problem. Here we investigate the design of model-based identifier (MBID) for a normal-mode model developed from a shallow water ocean experiment and then apply it to a set of experimental data demonstrating the feasibility of this approach. In this problem we show how the processor can be structured to estimate the horizontal wave numbers directly from measured pressure sound speed thereby eliminating the need for synthetic aperture processing or a propagation model solution. Ocean acoustic signal processing has made great strides over the past decade necessitated by the development of quieter submarines and the recent proliferation of diesel powered vessels.

  6. Theory and experiment research of two-dimension acoustic metamaterial

    NASA Astrophysics Data System (ADS)

    Sun, Hongwei; Li, JianFeng; Li, Zhiming; Li, Ying

    2013-04-01

    This paper presents modeling and analysis methods for design of a acoustic metamaterial panel consisting of two isotropic plates and small membrane-mass subsystems for absorption of low frequencies transverse elastic waves. Two models of a unit cell are derived and used to demonstrate the existence of negative effective material properties. Moreover, the design of experiment sample confirms that the model and analysis methods are valid. (1) The frequency of the membrane-mass subsystems are uniform distribution in whole acoustic metamaterial panel have two vibration models. (2) The different distributions of membrane-mass subsystems and their resonance frequencies result in different vibration isolation characteristics. (3) PSV is used to test and the result show that a low frequency wave absorber does not require nano-manufacturing techniques. (4) If we design the frequency of the membrane-mass subsystems different it can change the character of the metamaterial panel.

  7. Acoustic processing method for MS/MS experiments

    NASA Technical Reports Server (NTRS)

    Whymark, R. R.

    1973-01-01

    Acoustical methods in which intense sound beams can be used to control the position of objects are considered. The position control arises from the radiation force experienced when a body is placed in a sound field. A description of the special properties of intense sound fields useful for position control is followed by a discussion of the more obvious methods of position, namely the use of multiple sound beams. A new type of acoustic position control device is reported that has advantages of simplicity and reliability and utilizes only a single sound beam. Finally a description is given of an experimental single beam levitator, and the results obtained in a number of key levitation experiments.

  8. Parabolic equation solution of seismo-acoustics problems involving variations in bathymetry and sediment thickness.

    PubMed

    Collis, Jon M; Siegmann, William L; Jensen, Finn B; Zampolli, Mario; Küsel, Elizabeth T; Collins, Michael D

    2008-01-01

    Recent improvements in the parabolic equation method are combined to extend this approach to a larger class of seismo-acoustics problems. The variable rotated parabolic equation [J. Acoust. Soc. Am. 120, 3534-3538 (2006)] handles a sloping fluid-solid interface at the ocean bottom. The single-scattering solution [J. Acoust. Soc. Am. 121, 808-813 (2007)] handles range dependence within elastic sediment layers. When these methods are implemented together, the parabolic equation method can be applied to problems involving variations in bathymetry and the thickness of sediment layers. The accuracy of the approach is demonstrated by comparing with finite-element solutions. The approach is applied to a complex scenario in a realistic environment. PMID:18177137

  9. Experiments on metasurface carpet cloaking for audible acoustics

    NASA Astrophysics Data System (ADS)

    Faure, Cédric; Richoux, Olivier; Félix, Simon; Pagneux, Vincent

    2016-02-01

    We present experiments on acoustic carpet cloaking by using a metasurface made of graded Helmholtz resonators. The thin metasurface, placed over the object to hide, is designed such that the reflection phase shifts of the resonators at the resonance frequency are tuned to compensate the shape of the object to cloak. Experimental as well as numerical results show the efficiency of the cloak at the resonance frequency. The reflection of a short pulse is also reported to inspect the broadband character of the cloak.

  10. An Acoustic Demonstration Model for CW and Pulsed Spectrosocopy Experiments

    NASA Astrophysics Data System (ADS)

    Starck, Torben; Mäder, Heinrich; Trueman, Trevor; Jäger, Wolfgang

    2009-06-01

    High school and undergraduate students have often difficulties if new concepts are introduced in their physics or chemistry lectures. Lecture demonstrations and references to more familiar analogues can be of great help to the students in such situations. We have developed an experimental setup to demonstrate the principles of cw absorption and pulsed excitation - emission spectroscopies, using acoustical analogues. Our radiation source is a speaker and the detector is a microphone, both controlled by a computer sound card. The acoustical setup is housed in a plexiglas box, which serves as a resonator. It turns out that beer glasses are suitable samples; this also helps to keep the students interested! The instrument is controlled by a LabView program. In a cw experiment, the sound frequency is swept through a certain frequency range and the microphone response is recorded simultaneously as function of frequency. A background signal without sample is recorded, and background subtraction yields the beer glass spectrum. In a pulsed experiment, a short sound pulse is generated and the microphone is used to record the resulting emission signal of the beer glass. A Fourier transformation of the time domain signal gives then the spectrum. We will discuss the experimental setup and show videos of the experiments.

  11. Oscillating load-induced acoustic emission in laboratory experiment

    USGS Publications Warehouse

    Ponomarev, Alexander; Lockner, David A.; Stroganova, S.; Stanchits, S.; Smirnov, V.

    2010-01-01

    Spatial and temporal patterns of acoustic emission (AE) were studied. A pre-fractured cylinder of granite was loaded in a triaxial machine at 160 MPa confining pressure until stick-slip events occurred. The experiments were conducted at a constant strain rate of 10−7 s−1 that was modulated by small-amplitude sinusoidal oscillations with periods of 175 and 570 seconds. Amplitude of the oscillations was a few percent of the total load and was intended to simulate periodic loading observed in nature (e.g., earth tides or other sources). An ultrasonic acquisition system with 13 piezosensors recorded acoustic emissions that were generated during deformation of the sample. We observed a correlation between AE response and sinusoidal loading. The effect was more pronounced for higher frequency of the modulating force. A time-space spectral analysis for a “point” process was used to investigate details of the periodic AE components. The main result of the study was the correlation of oscillations of acoustic activity synchronized with the applied oscillating load. The intensity of the correlated AE activity was most pronounced in the “aftershock” sequences that followed large-amplitude AE events. We suggest that this is due to the higher strain-sensitivity of the failure area when the sample is in a transient, unstable mode. We also found that the synchronization of AE activity with the oscillating external load nearly disappeared in the period immediately after the stick-slip events and gradually recovered with further loading.

  12. Student Microwave Experiments Involving the Doppler Effect.

    ERIC Educational Resources Information Center

    Weber, F. Neff; And Others

    1980-01-01

    Described is the use of the Doppler Effect with microwaves in the measurement of the acceleration due to gravity of falling objects. The experiments described add to the repertoire of quantitative student microwave experiments. (Author/DS)

  13. Sperm whale predator-prey interactions involve chasing and buzzing, but no acoustic stunning

    PubMed Central

    Fais, A.; Johnson, M.; Wilson, M.; Aguilar Soto, N.; Madsen, P. T.

    2016-01-01

    The sperm whale carries a hypertrophied nose that generates powerful clicks for long-range echolocation. However, it remains a conundrum how this bizarrely shaped apex predator catches its prey. Several hypotheses have been advanced to propose both active and passive means to acquire prey, including acoustic debilitation of prey with very powerful clicks. Here we test these hypotheses by using sound and movement recording tags in a fine-scale study of buzz sequences to relate the acoustic behaviour of sperm whales with changes in acceleration in their head region during prey capture attempts. We show that in the terminal buzz phase, sperm whales reduce inter-click intervals and estimated source levels by 1–2 orders of magnitude. As a result, received levels at the prey are more than an order of magnitude below levels required for debilitation, precluding acoustic stunning to facilitate prey capture. Rather, buzzing involves high-frequency, low amplitude clicks well suited to provide high-resolution biosonar updates during the last stages of capture. The high temporal resolution helps to guide motor patterns during occasionally prolonged chases in which prey are eventually subdued with the aid of fast jaw movements and/or buccal suction as indicated by acceleration transients (jerks) near the end of buzzes. PMID:27340122

  14. Sperm whale predator-prey interactions involve chasing and buzzing, but no acoustic stunning.

    PubMed

    Fais, A; Johnson, M; Wilson, M; Aguilar Soto, N; Madsen, P T

    2016-01-01

    The sperm whale carries a hypertrophied nose that generates powerful clicks for long-range echolocation. However, it remains a conundrum how this bizarrely shaped apex predator catches its prey. Several hypotheses have been advanced to propose both active and passive means to acquire prey, including acoustic debilitation of prey with very powerful clicks. Here we test these hypotheses by using sound and movement recording tags in a fine-scale study of buzz sequences to relate the acoustic behaviour of sperm whales with changes in acceleration in their head region during prey capture attempts. We show that in the terminal buzz phase, sperm whales reduce inter-click intervals and estimated source levels by 1-2 orders of magnitude. As a result, received levels at the prey are more than an order of magnitude below levels required for debilitation, precluding acoustic stunning to facilitate prey capture. Rather, buzzing involves high-frequency, low amplitude clicks well suited to provide high-resolution biosonar updates during the last stages of capture. The high temporal resolution helps to guide motor patterns during occasionally prolonged chases in which prey are eventually subdued with the aid of fast jaw movements and/or buccal suction as indicated by acceleration transients (jerks) near the end of buzzes. PMID:27340122

  15. Experiences with nonlinear dynamics of panels and membranes considering fluid-structure interaction and acoustic fatigue

    SciTech Connect

    Ferman, M.A.

    1994-12-31

    A collection of some highlights of the Author`s experiences with nonlinear dynamics in analyses and tests of Panels and Membranes encountered over the past 40 years is given. The primary focus is placed on a major block of his work since the early 70`s, involving work with fluid-structure interaction with Panels and Membranes, and with efforts in Acoustic Fatigue of Panels. While the Author had encountered nonlinear problems throughout Ins career involving flutter, vibration in general, and dynamic thrust instability; it was the more recent work with panels and membranes that greatly expanded his experience. This was triggered by the advent of highly maneuverable aircraft, powered by large powerful, noisy engines, and new materials in the mid 70`s. The significance of nonlinearity for these applications is most obvious from the results shown here-it simply cannot be ignored for optimal, safe design.

  16. 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).

  17. Transition to Kindergarten: Family Experiences and Involvement

    ERIC Educational Resources Information Center

    McIntyre, Laura Lee; Eckert, Tanya L.; Fiese, Barbara H.; DiGennaro, Florence D.; Wildenger, Leah K.

    2007-01-01

    The transition to kindergarten is an important developmental milestone for young children, their families, and teachers. Preparing students for successful kindergarten transition has been identified as a national priority, yet the degree to which parents are involved in kindergarten preparation is rarely considered. This study investigated the…

  18. Acoustic interactions between an altitude test facility and jet engine plumes: Theory and experiments

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Jones, R. R., III; Tam, C. K.; Massey, K. C.; Fleming, A. J.

    1992-01-01

    The overall objective of the described effort was to develop an understanding of the physical mechanisms involved in the flow/acoustic interactions experienced in full-scale altitude engine test facilities. This is done by conducting subscale experiments and through development of a theoretical model. Model cold jet experiments with an axisymmetric convergent nozzle are performed in a test setup that stimulates a supersonic jet exhausting into a cylindrical diffuser. The measured data consist of detailed flow visualization data and acoustic spectra for a free and a ducted plume. It is shown that duct resonance is most likely responsible by theoretical calculations. Theoretical calculations also indicate that the higher discrete tones observed in the measurements are related to the screech phenomena. Limited experiments on the sensitivity of a free 2-D, C-D nozzle to externally imposed sound are also presented. It is shown that a 2-D, C-D nozzle with a cutback is less excitable than a 2-D C-D nozzle with no cutback. At a pressure ratio of 1.5 unsteady separation from the diverging walls of the nozzle is noticed. This separation switches from one wall to the opposite wall thus providing an unsteady deflection of the plume. It is shown that this phenomenon is related to the venting provided by the cutback section.

  19. Using acoustic cavitation to enhance chemotherapy of DOX liposomes: experiment in vitro and in vivo.

    PubMed

    Zhao, Ying-Zheng; Dai, Dan-Dan; Lu, Cui-Tao; Lv, Hai-Feng; Zhang, Yan; Li, Xing; Li, Wen-Feng; Wu, Yan; Jiang, Lei; Li, Xiao-Kun; Huang, Pin-Tong; Chen, Li-Juan; Lin, Min

    2012-09-01

    Experiments in vitro and in vivo were designed to investigate tumor growth inhibition of chemotherapeutics-loaded liposomes enhanced by acoustic cavitation. Doxorubicin-loaded liposomes (DOX liposomes) were used in experiments to investigate acoustic cavitation mediated effects on cell viability and chemotherapeutic function. The influence of lingering sensitive period after acoustic cavitation on tumor inhibition was also investigated. Animal experiment was carried out to verify the practicability of this technique in vivo. From experiment results, blank phospholipid-based microbubbles (PBM) combined with ultrasound (US) at intensity below 0.3 W/cm² could produce acoustic cavitation which maintained cell viability at high level. Compared with DOX solution, DOX liposomes combined with acoustic cavitation exerted effective tumor inhibition in vitro and in vivo. The lingering sensitive period after acoustic cavitation could also enhance the susceptibility of tumor to chemotherapeutic drugs. DOX liposomes could also exert certain tumor inhibition under preliminary acoustic cavitation. Acoustic cavitation could enhance the absorption efficiency of DOX liposomes, which could be used to reduce DOX adverse effect on normal organs in clinical chemotherapy. PMID:22188116

  20. Towards field and laboratory experiments with ocean acoustic-gravity waves

    NASA Astrophysics Data System (ADS)

    Oliveira, Tiago; Kadri, Usama; Lin, Ying-Tsong; Morozov, Andrey

    2016-04-01

    Acoustic-gravity waves (AGWs) can be generated in the ocean by mechanical energy transfer from the Earth's crust (e.g. earthquakes or volcanoes) and by energy transfer occurring at the water surface (e.g. interaction of opposing gravity waves, ice-quakes or localized pressure changes). Recent theoretical studies shed light on the underlying physics of the generation and propagation of AGWs in the ocean. However, these theories are yet to be verified further with very challenging field experiments due to the associated low frequency signals required, and ambient disturbances involved. Here, we present a unique setup of field experiments and large scale laboratory tests to verify the main physical properties of AGWs in ocean generated by different types of sources. We also present a novel methodology to generate and measure AGWs in the ocean.

  1. Physical oceanography and acoustic propagation during LADC experiment in the Gulf of Mexico in 2001

    NASA Astrophysics Data System (ADS)

    Vinogradov, Sergey; Caruthers, Jerald W.; Rayborn, Grayson H.; Udovydchenkov, Ilya A.; Sidorovskaia, Natalia A.; Rypina, Irina I.; Newcomb, Joal J.; Fisher, Robert A.; Ioup, George E.; Ioup, Juliette W.

    2003-04-01

    The Littoral Acoustic Demonstration Center (LADC) deployed three environmental and acoustic moorings in a downslope line just off the Mississippi River Delta in the northern Gulf of Mexico in an area of a large concentration of sperm whales in July 2001. The measurement of whale vocalizations and, more generally, ambient noise, were the objectives of the experiment. Each mooring had a single hydrophone autonomously recording Environmental Acoustic Recording System (EARS) obtained from the U.S. Naval Oceanographic Office and modified to recorded signals up to 5859 Hz continuously for 36 days. Also, self-recording, environmental sensors were attached to the moorings to obtain profiles of time series data of temperature and salinity. Satellite imagery and NOAA mooring data were gathered for an analysis of eddy formations and movement in the Gulf. This paper will discuss the possible environmental impact of two events that occurred during the experiment: the passage of Tropical Storm Barry and the movement of the remnants of an eddy in the area. Discussed also will be the expected effects of these events on acoustic propagation based on modeling, which are carried out for long range and low frequency (300 km and 500 Hz) using the normal-mode acoustic model SWAMP (Shallow Water Acoustic Modal Propagation by M. F. Werby and N. A. Sidorovskaia) and for short range and high frequency (10 km and 5000 Hz) using the parabolic-equation acoustic model RAM (Range-dependent Acoustic model by M. Collins). [Work supported by ONR.

  2. Ray dynamics in a long-range acoustic propagation experiment.

    PubMed

    Beron-Vera, Francisco J; Brown, Michael G; Colosi, John A; Tomsovic, Steven; Virovlyansky, Anatoly L; Wolfson, Michael A; Zaslavsky, George M

    2003-09-01

    A ray-based wave-field description is employed in the interpretation of broadband basin-scale acoustic propagation measurements obtained during the Acoustic Thermometry of Ocean Climate program's 1994 Acoustic Engineering Test. Acoustic observables of interest are wavefront time spread, probability density function (PDF) of intensity, vertical extension of acoustic energy in the reception finale, and the transition region between temporally resolved and unresolved wavefronts. Ray-based numerical simulation results that include both mesoscale and internal-wave-induced sound-speed perturbations are shown to be consistent with measurements of all the aforementioned observables, even though the underlying ray trajectories are predominantly chaotic, that is, exponentially sensitive to initial and environmental conditions. Much of the analysis exploits results that relate to the subject of ray chaos; these results follow from the Hamiltonian structure of the ray equations. Further, it is shown that the collection of the many eigenrays that form one of the resolved arrivals is nonlocal, both spatially and as a function of launch angle, which places severe restrictions on theories that are based on a perturbation expansion about a background ray. PMID:14514177

  3. Exploratory experiments on acoustic oscillations driven by periodic vortex shedding

    NASA Astrophysics Data System (ADS)

    Dunlap, R.; Brown, R. S.

    1981-03-01

    Periodic vortex shedding is investigated as a mechanism by which low-amplitude pressure oscillations can be generated in segmented solid propellant rocket engines. Acoustic responses were monitored in an acoustically isolated flow chamber with two flow restrictors in the flow path as a function of resistor spacing and flow Mach number. At Mach 0.042, the maximum acoustic response is observed with a marked increase in the amplitude of the wave corresponding to the third acoustic mode of the chamber. Reduction of the Mach number by a factor of three is found to excite the first longitudinal mode of the chamber at the same restrictor spacing. Attempts to produce the second axial mode are unsuccessful when the restrictors were kept at the center of the chamber, indicating the importance of restrictor position relative to the acoustic mode structure. The restrictor spacing at which maximum response is obtained indicates a Strouhal number of 0.8 characterizing the vortex shedding frequency, in agreement with calculations. The results thus demonstrate that a significant (5-10%) pressure oscillation can be generated by coupling from periodic vortex shedding

  4. NATO TG-53: acoustic detection of weapon firing joint field experiment

    NASA Astrophysics Data System (ADS)

    Robertson, Dale N.; Pham, Tien; Scanlon, Michael V.; Srour, Nassy; Reiff, Christian G.; Sim, Leng K.; Solomon, Latasha; Thompson, Dorothea F.

    2006-05-01

    In this paper, we discuss the NATO Task Group 53 (TG-53) acoustic detection of weapon firing field joint experiment at Yuma Proving Ground during 31 October to 4 November 2005. The participating NATO countries include France, the Netherlands, UK and US. The objectives of the joint experiments are: (i) to collect acoustic signatures of direct and indirect firings from weapons such as sniper, mortar, artillery and C4 explosives and (ii) to share signatures among NATO partners from a variety of acoustic sensing platforms on the ground and in the air distributed over a wide area.

  5. Quantitative Analysis Of Acoustic Emission From Rock Fracture Experiments

    NASA Astrophysics Data System (ADS)

    Goodfellow, Sebastian David

    This thesis aims to advance the methods of quantitative acoustic emission (AE) analysis by calibrating sensors, characterizing sources, and applying the results to solve engi- neering problems. In the first part of this thesis, we built a calibration apparatus and successfully calibrated two commercial AE sensors. The ErgoTech sensor was found to have broadband velocity sensitivity and the Panametrics V103 was sensitive to surface normal displacement. These calibration results were applied to two AE data sets from rock fracture experiments in order to characterize the sources of AE events. The first data set was from an in situ rock fracture experiment conducted at the Underground Research Laboratory (URL). The Mine-By experiment was a large scale excavation response test where both AE (10 kHz - 1 MHz) and microseismicity (MS) (1 Hz - 10 kHz) were monitored. Using the calibration information, magnitude, stress drop, dimension and energy were successfully estimated for 21 AE events recorded in the tensile region of the tunnel wall. Magnitudes were in the range -7.5 < Mw < -6.8, which is consistent with other laboratory AE results, and stress drops were within the range commonly observed for induced seismicity in the field (0.1 - 10 MPa). The second data set was AE collected during a true-triaxial deformation experiment, where the objectives were to characterize laboratory AE sources and identify issues related to moving the analysis from ideal in situ conditions to more complex laboratory conditions in terms of the ability to conduct quantitative AE analysis. We found AE magnitudes in the range -7.8 < Mw < -6.7 and as with the in situ data, stress release was within the expected range of 0.1 - 10 MPa. We identified four major challenges to quantitative analysis in the laboratory, which in- hibited our ability to study parameter scaling (M0 ∝ fc -3 scaling). These challenges were 0c (1) limited knowledge of attenuation which we proved was continuously evolving, (2

  6. Modeling Nonlinear Acoustic Standing Waves in Resonators: Theory and Experiments

    NASA Technical Reports Server (NTRS)

    Raman, Ganesh; Li, Xiaofan; Finkbeiner, Joshua

    2004-01-01

    The overall goal of the cooperative research with NASA Glenn is to fundamentally understand, computationally model, and experimentally validate non-linear acoustic waves in enclosures with the ultimate goal of developing a non-contact acoustic seal. The longer term goal is to transition the Glenn acoustic seal innovation to a prototype sealing device. Lucas and coworkers are credited with pioneering work in Resonant Macrosonic Synthesis (RMS). Several Patents and publications have successfully illustrated the concept of Resonant Macrosonic Synthesis. To utilize this concept in practical application one needs to have an understanding of the details of the phenomenon and a predictive tool that can examine the waveforms produced within resonators of complex shapes. With appropriately shaped resonators one can produce un-shocked waveforms of high amplitude that would result in very high pressures in certain regions. Our goal is to control the waveforms and exploit the high pressures to produce an acoustic seal. Note that shock formation critically limits peak-to-peak pressure amplitudes and also causes excessive energy dissipation. Proper shaping of the resonator is thus critical to the use of this innovation.

  7. A note on an acoustic response during an engine nacelle flight experiment

    NASA Technical Reports Server (NTRS)

    Schoenster, James A.

    1990-01-01

    During a flight test study of the noise effects on laminar flow on the outside surface of a simulated engine nacelle, an intense acoustic response was observed. The aircraft speed at which this signal occurred and the frequency content of the signal fell within the test conditions of the experiment and had to be eliminated prior to continuing. The signal was identified as an aerodynamic excitation of an acoustic mode in the simulated by-pass duct of the nacelle. By modifying the trailing edges of the support struts of the nacelle, the aerodynamic excitation was changed enough to eliminate the resonant response of the offending duct modes, eliminating the unwanted acoustic problem.

  8. EVIDENCE FOR THE INVOLVEMENT OF ASSOCIATIVE CONDITIONING IN REFLEX MODIFICATION OF THE ACOUSTIC STARTLE RESPONSE WITH GAPS IN BACKGROUND NOISE

    EPA Science Inventory

    The experiments reported here were designed to determine the role of associative conditioning in reflex modification of the acoustic startle response using gaps in background noise. xperiments were conducted with independent, naive groups of adult Long Evans hooded rats tested us...

  9. The vibro-acoustic launch protection experiment overview and flight results summary

    NASA Astrophysics Data System (ADS)

    Gerhart, Charlotte M.; Henderson, B. Kyle; Griffin, Steve; Lazzaro, Anthony; Evert, Michael E.; McCrary, Warren; Ardelean, Emil V.

    2004-07-01

    The cost of performing any mission on orbit is a strong function of the cost of getting the mass into orbit and the mass of a spacecraft is driven by the launch loads that the components must be deigned to survive. Additionally, these design loads vary between launch vehicles so if circumstances arise that require a change in launch vehicle significant time and money can be spent in modifying and testing to meet different requirements. Technologies that reduce both the vibration and acoustic environments during launch have the potential to both reduce the design load levels, and eventually equalize them between boosters. To this end the Air Force Research Laboratory, Space Vehicles Directorate in cooperation with the Space Test Program, Boeing SVS, CSA Engineering, and Delta Velocity have been investigating methods to decrease the acoustic and vibration loads induced on payloads by the launch environment and demonstrating them on a sounding rocket launch. The Vibro-Acoustic Launch Protection Experiment (VALPE) mission included an acoustically designed Chamber-Core skin, two passive/active vibration isolation experiments, a passive/active acoustic damping experiment, and an energy recovery experiment integrated onto a Terrier-Improved Orion sounding rocket and launched from NASA Wallops Island. A description of the overall mission, experiments, and general results from the flight test are discussed.

  10. Bioacoustic Field Research: A Primer to Acoustic Analyses and Playback Experiments With Primates

    PubMed Central

    FISCHER, JULIA; NOSER, RAHEL; HAMMERSCHMIDT, KURT

    2013-01-01

    Acoustic analyses of primate vocalizations as well as playback experiments are staple methods in primatology. Acoustic analyses have been used to investigate the influence of factors such as individuality, context, sex, age, and size on variation in calls. More recent studies have expanded our knowledge on the effects of phylogenetic relatedness and the structure of primate vocal repertoires in general. Complementary playback experiments allow direct testing of hypotheses regarding the attribution of meaning to calls, the cognitive mechanisms underpinning responses, and/or the adaptive value of primate behavior. After briefly touching on the historical background of this field of research, we first provide an introduction to recording primate vocalizations and discuss different approaches to describe primate calls in terms of their temporal and spectral properties. Second, we present a tutorial regarding the preparation, execution, and interpretation of field playback experiments, including a review of studies that have used such approaches to investigate the responses to acoustic variation in calls including the integration of contextual and acoustic information, recognition of kin and social relationships, and social knowledge. Based on the review of the literature and our own experience, we make a number of recommendations regarding the most common problems and pitfalls. The power of acoustic analyses typically hinges on the quality of the recordings and the number of individuals represented in the sample. Playback experiments require profound knowledge of the natural behavior of the animals for solid interpretation; experiments should be conducted sparingly, to avoid habituation of the subjects to the occurrence of the calls; experimenter-blind designs chosen whenever possible; and researchers should brace themselves for long periods of waiting times until the appropriate moments to do the experiment arise. If all these aspects are considered, acoustic analyses

  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. Acoustic Modal Patterns and Striations (AMPS) experiment G-325, Norfolk Public Schools

    NASA Technical Reports Server (NTRS)

    Young, Joy W.

    1995-01-01

    This paper will describe how high school students with the guidance of volunteer mentors were able to successfully complete an acoustics space experiment. Some of the NORSTAR program strategies used to effectively accomplish this goal will be discussed. The experiment and present status of results will be explained.

  13. The Development of Acoustic Experiments for Off-Campus Teaching and Learning

    ERIC Educational Resources Information Center

    Wild, Graham; Swan, Geoff

    2011-01-01

    In this article, we show the implementation of a computer-based digital storage oscilloscope (DSO) and function generator (FG) using the computer's soundcard for off-campus acoustic experiments. The microphone input is used for the DSO, and a speaker jack is used as the FG. In an effort to reduce the cost of implementing the experiment, we examine…

  14. Resolution Analysis for Experiment Planning of a Nonlinear Seafloor Acoustic Inverse Problem

    NASA Astrophysics Data System (ADS)

    Ganse, A. A.; Odom, R. I.

    2007-12-01

    Geoacoustic inversion is the estimation of physical properties of the ocean bottom as a continuous function of position (or depth) in the seafloor given acoustic receptions in the water column. It is closely related to marine reflection seismology but also has features of refraction seismology, and uses sonar equipment and less than ideal geometries because accurate scientific determination of the seafloor may not be the primary goal of the experiments. However, the authors show how a pre-measurement inverse theory resolution analysis can be used as part of experiment planning regarding sensor placement and ship tracks, such that a desire for an experimental configuration giving the most information in bottom inversion can be quantitatively balanced with that for other needs like tracking and communication. This nonlinear geoacoustic inverse problem is ill-posed, so that one can only estimate the continuous function of seafloor properties to a limited resolution. This limited resolution varies with experiment geometry, frequency, and other such factors, and can be quantified in either a frequentist or Bayesian framework. Given statistics of the measurement noise (but without any new measurements themselves), the resolution can be quantified exactly for a linear inverse problem, and compared between different experiment geometries. Nonlinear problems complicate this picture, but if the problem can be transformed into a weakly nonlinear form then the resolution may still be explored in an approximate sense and used as a tool in the planning phase. The ideal situation is when previous seafloor estimates exist for the same region in which a new experiment with new geometry and configuration is being planned. For the scenario without previous results, a somewhat more ad-hoc approach can still compare changes in resolution across different seafloor models. This presentation demonstrates the technique for a synthetic problem involving a single stationary source and a

  15. Acoustic Propagation Studies For Sperm Whale Phonation Analysis During LADC Experiments

    NASA Astrophysics Data System (ADS)

    Sidorovskaia, Natalia A.; Ioup, George E.; Ioup, Juliette W.; Caruthers, Jerald W.

    2004-11-01

    The Littoral Acoustic Demonstration Center (LADC) conducted a series of passive acoustic experiments in the Northern Gulf of Mexico and the Ligurian Sea in 2001 and 2002. Environmental and acoustic moorings were deployed in areas of large concentrations of marine mammals (mainly, sperm whales). Recordings and analysis of whale phonations are among the objectives of the project. Each mooring had a single autonomously recording hydrophone (Environmental Acoustic Recording System (EARS)) obtained from the U.S. Naval Oceanographic Office after modification to record signals up to 5,859 Hz in the Gulf of Mexico and up to 12,500 Hz in the Ligurian Sea. Self-recording environmental sensors, attached to the moorings, and concurrent environmental ship surveys provided the environmental data for the experiments. The results of acoustic simulations of long-range propagation of the broad-band (500-6,000 Hz) phonation pulses from a hypothetical whale location to the recording hydrophone in the experimental environments are presented. The utilization of the simulation results for an interpretation of the spectral features observed in whale clicks and for the development of tracking algorithms from single hydrophone recordings based on the identification of direct and surface and bottom reflected arrivals are discussed. [Research supported by ONR.

  16. Acoustic forcing on swirling flow: experiments and simulation

    NASA Astrophysics Data System (ADS)

    Hubschmid, W.; Denisov, A.; Biagioli, F.

    2014-09-01

    We investigated the effect of sound irradiated from loudspeakers on the flow of preheated air in the combustion chamber of a swirl burner. The temporally periodic pattern of the flow generated by the sound was detected by fast particle image velocimetry (PIV), with a repetition rate that was adapted to the observation of 12 phase angles of the irradiated monochromatic sound. The strong observed movement of the air is related to the movement by the sound itself, as determined by the pressure measurements with microphones. The PIV measurements reveal also a nonlinear interaction between the irradiated sound and the precession of the vortex core. The accuracy of the sound measurements was tested by determining in quiescent air the acoustic velocity by microphones and as well by PIV; good agreement was obtained thereby. Numerical calculations, using large eddy simulation and accounting for the sound forcing by variation in the mass flow at the inlet of the computational domain, approximately reproduce some of the experimental results.

  17. Technical challenges involved in supporting the Lambda Point Experiment

    NASA Technical Reports Server (NTRS)

    Petrac, D.; Israelsson, U.; Otth, D.; Simmons, L.; Staats, J.; Thompson, A.

    1990-01-01

    The Lambda Point Experiment (LPE) is one of the instruments included in the U.S. Microgravity Payload Mission 1 planned for one of the Space Shuttle flights in 1992. The objective of the experiment is to measure the heat capacity of liquid helium within a narrow interval around the transition between superfluid and normal helium (the lambda point) with an unprecedented temperature resolution of about 10 to the -10th. Multiple technical challenges are presented in the areas of structural support, safety analysis, and modal frequency tests. This paper describes the technical challenges of JPL's multidisciplinary involvement in support of these experiments in microgravity.

  18. Dan Poskevich demonstrates experiment for STS student involvement project

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Dan Poskevich, a college student, demonstrates an experiment he developed for the Space Transportation System (STS) student involvement project. In the aluminum box are thousands of honeybees constructing a honeycomb. Poskevich gave a brief demonstration for news media representatives in the Space Shuttle one-G trainer in JSC's mockup and integration lab.

  19. School Experiences of an Adolescent with Medical Complexities Involving Incontinence

    ERIC Educational Resources Information Center

    Filce, Hollie Gabler; Bishop, John B.

    2014-01-01

    The educational implications of chronic illnesses which involve incontinence are not well represented in the literature. The experiences of an adolescent with multiple complex illnesses, including incontinence, were explored via an intrinsic case study. Data were gathered from the adolescent, her mother, and teachers through interviews, email…

  20. 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.

  1. Selective focusing through target identification and experimental acoustic signature extraction: Numerical experiments.

    PubMed

    Rodriguez, S; Jacob, X; Gibiat, V

    2016-05-01

    Using transducer arrays and appropriate emission delays allow to focus acoustic waves at a chosen location in a medium. The focusing spatial accuracy depends on the accurate knowledge of its acoustic properties. When those properties are unknown, methods based on the Time-Reversal principle allow accurate focusing. Still, these methods are either intrusive (an active source has to be introduced at the target location first), either blind (the target cannot be selected in the presence of several objects.) The purpose of the present work is to achieve non-invasive accurate focusing on a selected target using inaccurate acoustic properties for the investigated medium. Potential applications are for instance noninvasive surgery based on High Intensity Focused Ultrasound (HIFU). Numerical experiments are presented and demonstrate accurate focusing on a previously designated target located in an unknown heterogeneous medium. PMID:26890791

  2. Functional referents and acoustic similarity: field playback experiments with rhesus monkeys.

    PubMed

    Hauser

    1998-06-01

    Rhesus monkeys, Macaca mulatta, on the island of Cayo Santiago, Puerto Rico produce one or more of five acoustically distinctive calls when they find food. Three of these calls ('warbles', 'harmonic arches' and 'chirps') are produced by individuals finding high-quality, rare food items, whereas the other two calls ('coos' and 'grunts') are produced upon encountering lower-quality, common food items, and in non-food contexts as well. To determine how rhesus classify such acoustic variation, I conducted habituation experiments using a subset of the five call types. I designed experiments to reveal whether classification is based primarily on acoustic features or on the basis of a call's functional referent; caller identity was held constant within sessions. Habituation to 'warbles' transferred to 'harmonic arches', and vice versa. Thus, although these two calls are acoustically distinctive, they appeared to be perceptually clustered into one category based on referential similarities. In contrast, habituation to 'grunts' was followed by dishabituation to 'warbles' or 'harmonic arches', and habituation to 'warbles' or 'harmonic arches' was followed by dishabituation to 'grunts'. Dishabituation could be due to acoustic or referential differences. Significantly, the magnitude of the dishabituating response was asymmetric and depended upon the call type used in the habituation series. Thus, when subjects were habituated to 'grunts', they responded significantly more to tests of 'warbles' or 'harmonic arches' than when the sequence was reversed. These results suggest that for rhesus monkey food-associated calls, referential differences carry more weight during perceptual classification than do acoustical differences. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour. PMID:9642008

  3. Experiments in Molecular Physics with an Acoustic Interferometer

    ERIC Educational Resources Information Center

    Rossing, Thomas D.

    1973-01-01

    A device which provides an inexpensive means for making precise studies of the kinetics of gas molecules is discussed. Two experiments are described: (1) Measurement of the vibrational relaxation time of gas molecules and (2) determination of intermolecular forces in molecules. (Author/DF)

  4. Microbubble-induced sonoporation involved in ultrasound-mediated DNA transfection in vitro at low acoustic pressures.

    PubMed

    Qiu, Yuanyuan; Zhang, Chunbing; Tu, Juan; Zhang, Dong

    2012-05-11

    In the present work, human breast cancer cells MCF-7 mixed with polyethylenimine: deoxyribonucleic acid complex and microbubbles were exposed to 1-MHz ultrasound at low acoustic driving pressures ranging from 0.05 to 0.3 MPa. The sonoporation pores generated on the cell membrane were examined with scanning electron microscopy. The transfection efficiency and cell viability were evaluated with flow cytometry. The results showed that ultrasound sonication under the current exposure condition could generate cell pores with mean size ranging from about 100 nm to 1.25 μm, and that larger sonoporation pores would be generated with the increasing acoustic pressure or longer treatment time, leading to the enhancement of transfection efficiency and the reduction of cell viability. The simulations based on the Marmottant model were performed to test the hypothesis that the microstreaming-induced shear stress might be involved in the mechanisms of the low-intensity ultrasound induced sonoporation. The calculated shear stress resulting from the micro-streaming ranged from 15 to 680 Pa corresponding to the applied acoustic pressures 0.05-0.3 MPa, which is sufficient to induce reversible sonoporation. This study indicates that the shear stress related bio-effects may provide a base for strategies aimed at targeted drug delivery. PMID:22498312

  5. Flow patterns and transport in Rayleigh surface acoustic wave streaming: combined finite element method and raytracing numerics versus experiments.

    PubMed

    Frommelt, Thomas; Gogel, Daniel; Kostur, Marcin; Talkner, Peter; Hänggi, Peter; Wixforth, Achim

    2008-10-01

    This work presents an approach for determining the streaming patterns that are generated by Rayleigh surface acoustic waves in arbitrary 3-D geometries by finite element method (FEM) simulations. An efficient raytracing algorithm is applied on the acoustic subproblem to avoid the unbearable memory demands and computational time of a conventional FEM acoustics simulation in 3-D. The acoustic streaming interaction is modeled by a body force term in the Stokes equation. In comparisons between experiments and simulated flow patterns, we demonstrate the quality of the proposed technique. PMID:18986877

  6. COMBUSTION ACOUSTICS DIAGNOSTICS

    EPA Science Inventory

    This is an Exploratory Research Project that was awarded by APPCD for research on developing an acoustic flame condition monitor. It will involve a bench scale experiment of 4-6 weeks duration to record adjacent audible energy of a Bunsen burner. The experiment will require a d...

  7. Numerical investigation of the seismo-acoustic responses of the Source Physics Experiment underground explosions

    NASA Astrophysics Data System (ADS)

    Antoun, T.; Ezzedine, S. M.; Vorobiev, O.; Glenn, L. A.

    2015-12-01

    We have performed three-dimensional high resolution simulations of underground explosions conducted recently in jointed rock outcrop as part of the Source Physics Experiment (SPE) being conducted at the Nevada National Security Site (NNSS). The main goal of the current study is to investigate the effects of the structural and geomechanical properties on the spall phenomena due to underground explosions and its subsequent effect on the seismo-acoustic signature at far distances. Two parametric studies have been undertaken to assess the impact of different 1) conceptual geological models including a single layer and two layers model, with and without joints and with and without varying geomechanical properties, and 2) depth of bursts of the explosions and explosion yields. Through these investigations we have explored not only the near-field response of the explosions but also the far-field responses of the seismic and the acoustic signatures. The near-field simulations were conducted using the Eulerian and Lagrangian codes, GEODYN and GEODYN -L, respectively, while the far-field seismic simulations were conducted using the elastic wave propagation code, WPP, and the acoustic response using the Kirchhoff-Helmholtz-Rayleigh time-dependent approximation code, KHR. Though a series of simulations, we have recorded the velocity field histories a) at the ground surface on an acoustic-source-patch for the acoustic simulations, and 2) on a seismic-source-box for the seismic simulations. We first analyzed the SPE3 and SPE4-prime experimental data and simulated results, and then simulated SPE5, SPE6/7 to anticipate their seismo-acoustic responses given conditions of uncertainties. SPE experiments were conducted in a granitic formation; we have extended the parametric study to include other geological settings such dolomite and alluvial formations. These parametric studies enabled us 1) investigating the geotechnical and geophysical key parameters that impact the seismo-acoustic

  8. Nonlinear acoustic experiments for landmine detection: the significance of the top-plate normal modes

    NASA Astrophysics Data System (ADS)

    Korman, Murray S.; Alberts, W. C. K., II; Sabatier, James M.

    2004-09-01

    In nonlinear acoustic detection experiments involving a buried inert VS 2.2 anti-tank landmine, airborne sound at two closely spaced primary frequencies f1 and f2 couple into the ground and interact nonlinearly with the soil-top pressure plate interface. Scattering generates soil vibration at the surface at the combination frequencies | m f1 +- n f2 | , where m and n are integers. The normal component of the particle velocity at the soil surface has been measured with a laser Doppler velocimeter (LDV) and with a geophone by Sabatier et. al. [SPIE Proceedings Vol. 4742, (695-700), 2002; Vol. 5089, (476-486), 2003] at the gravel lane test site. Spatial profiles of the particle velocity measured for both primary components and for various combination frequencies indicate that the modal structure of the mine is playing an important role. Here, an experimental modal analysis is performed on a VS 1.6 inert anti-tank mine that is resting on sand but is not buried. Five top-plate mode shapes are described. The mine is then buried in dry finely sifted natural loess soil and excited at f1 = 120 Hz and f2 = 130 Hz. Spatial profiles at the primary components and the nonlinearly generated f1 - (f2 - f1) component are characterized by a single peak. For the 2f1+f2 and 2f2 + f1 components, the doubly peaked profiles can be attributed to the familiar mode shape of a timpani drum (that is shifted lower in frequency due to soil mass loading). Other nonlinear profiles appear to be due to a mixture of modes. This material is based upon work supported by the U. S. Army RDECOM CERDEC Night Vision and Electronic Sensors Directorate under Contract DAAB15-02-C-0024.

  9. 2D fluid simulations of acoustic waves in pulsed ICP discharges: Comparison with experiments

    NASA Astrophysics Data System (ADS)

    Despiau-Pujo, Emilie; Cunge, Gilles; Sadeghi, Nader; Braithwaite, N. St. J.

    2012-10-01

    Neutral depletion, which is mostly caused by gas heating under typical material processing conditions, is an important phenomenon in high-density plasmas. In low pressure pulsed discharges, experiments show that additional depletion due to electron pressure (Pe) may have a non-negligible influence on radical transport [1]. To evaluate this effect, comparisons between 2D fluid simulations and measurements of gas convection in Ar/Cl2 pulsed ICP plasmas are reported. In the afterglow, Pe drops rapidly by electron cooling which generates a neutral pressure gradient between the plasma bulk and the reactor walls. This in turn forces the cold surrounding gas to move rapidly towards the center, thus launching an acoustic wave in the reactor. Time-resolved measurements of atoms drift velocity and gas temperature by LIF and LAS in the early afterglow are consistent with gas drifting at acoustic wave velocity followed by rapid gas cooling. Similar results are predicted by the model. The ion flux at the reactor walls is also shown to oscillate in phase with the acoustic wave due to ion-neutral friction forces. Finally, during plasma ignition, experiments show opposite phenomena when Pe rises.[4pt] [1] Cunge et al, APL 96, 131501 (2010)

  10. Comparison of simulations and data from a seismo-acoustic tank experiment.

    PubMed

    Collis, Jon M; Siegmann, William L; Collins, Michael D; Simpson, Harry J; Soukup, Raymond J

    2007-10-01

    A tank experiment was carried out to investigate underwater sound propagation over an elastic bottom in flat and sloping configurations. The purpose of the experiment was to evaluate range-dependent propagation models with high-quality experimental data. The sea floor was modeled as an elastic medium by a polyvinyl chloride slab. The relatively high rigidity of the slab requires accounting for shear waves in this environment. Acoustic measurements were obtained along virtual arrays in the water column using a robotic apparatus. Elastic parabolic equation solutions are in excellent agreement with data. PMID:17902835

  11. Mode tomography using signals from the Long Range Ocean Acoustic Propagation EXperiment (LOAPEX)

    NASA Astrophysics Data System (ADS)

    Chandrayadula, Tarun K.

    Ocean acoustic tomography uses acoustic signals to infer the environmental properties of the ocean. The procedure for tomography consists of low frequency acoustic transmissions at mid-water depths to receivers located at hundreds of kilometer ranges. The arrival times of the signal at the receiver are then inverted for the sound speed of the background environment. Using this principle, experiments such as the 2004 Long Range Ocean Acoustic Propagation EXperiment have used acoustic signals recorded across Vertical Line Arrays (VLAs) to infer the Sound Speed Profile (SSP) across depth. The acoustic signals across the VLAs can be represented in terms of orthonormal basis functions called modes. The lower modes of the basis set concentrated around mid-water propagate longer distances and can be inverted for mesoscale effects such as currents and eddies. In spite of these advantages, mode tomography has received less attention. One of the important reasons for this is that internal waves in the ocean cause significant amplitude and travel time fluctuations in the modes. The amplitude and travel time fluctuations cause errors in travel time estimates. The absence of a statistical model and the lack of signal processing techniques for internal wave effects have precluded the modes from being used in tomographic inversions. This thesis estimates a statistical model for modes affected by internal waves and then uses the estimated model to design appropriate signal processing methods to obtain tomographic observables for the low modes. In order to estimate a statistical model, this thesis uses both the LOAPEX signals and also numerical simulations. The statistical model describes the amplitude and phase coherence across different frequencies for modes at different ranges. The model suggests that Matched Subspace Detectors (MSDs) based on the amplitude statistics of the modes are the optimum detectors to make travel time estimates for modes up to 250 km. The mean of the

  12. Biological Significance of Acoustic Impacts on Marine Mammals: Examples Using an Acoustic Recording tag to Define Acoustic Exposure of Sperm Whales, Physeter catodon, Exposed to Airgun Sounds in Controlled Exposure Experiments

    NASA Astrophysics Data System (ADS)

    Tyack, P. L.; Johnson, M. P.; Madsen, P. T.; Miller, P. J.; Lynch, J.

    2006-05-01

    There has been considerable debate about how to regulate behavioral disruption in marine mammals. The U.S. Marine Mammal Protection Act prohibits "taking" marine mammals, including harassment, which is defined as injury or disruption of behavioral patterns. A 2005 report by the National Academy of Sciences focuses on the need to analyze acoustic impacts on marine mammal behavior in terms of biological significance. The report develops a model for predicting population consequences of acoustic impacts. One of the key data gaps involves methods to estimate the impact of disruption on an animal's ability to complete life functions critical for growth, survival, and reproduction. One of the few areas where theory and data are available involves foraging energetics. Patrick Miller in the next talk and I will discuss an example study designed to evaluate the impact of exposure to seismic survey on the foraging energetics of sperm whales. As petroleum exploration moves offshore to deep water, there is increasing overlap between seismic exploration and deep diving toothed whales such as the sperm whale which is listed by the US as an endangered species. With support from the US Minerals Management Service and the Industry Research Funding Coalition, we tagged sperm whales with tags that can record sound, orientation, acceleration, temperature and depth. Eight whales tagged in the Gulf of Mexico during 2002-2003 were subjects in 5 controlled experiments involving exposure to sounds of an airgun array. One critical component of evaluating effects involves quantifying exposure at the animal. While the on-axis signature of airgun arrays has been well quantified, there are few broadband calibrated measurements in the water column displaced horizontally away from the downward-directed beam. The acoustic recording tags provide direct data on sounds as received at the animals. Due to multipath propagation, multiple sound pulses were recorded on the tagged whales for each firing of

  13. Experiments on hypersonic boundary layer transition on blunt cones with acoustic-absorption coating

    NASA Astrophysics Data System (ADS)

    Shiplyuk, A.; Lukashevich, S.; Bountin, D.; Maslov, A.; Knaus, H.

    2012-01-01

    The laminar-turbulent transition is studied experimentally on a cone with an acoustic-absorption coating and with different nose bluntness in a high-speed flow. The acoustic-absorption coating is a felt metal sheet with a random microstructure. Experiments were carried out on a 1-meter length 7 degree cone at free-stream Mach number M = 8 and zero angle of attack. Locations of the laminar-turbulent transition are detected using heat flux distributions registered by calorimeter sensors. In addition, boundary layer pulsations are measured by means of ultrafast heat flux sensors. It is shown that the laminar-turbulent transition is caused by the second-mode instability, and the laminar run extends as the bluntness is increased. The porous coating effectively suppresses this instability for all tested bluntness values and 1.3-1.85 times extends the laminar run.

  14. The effect of boundaries on the ion acoustic beam-plasma instability in experiment and simulation

    SciTech Connect

    Rapson, Christopher; Grulke, Olaf; Matyash, Konstantin; Klinger, Thomas

    2014-05-15

    The ion acoustic beam-plasma instability is known to excite strong solitary waves near the Earth's bow shock. Using a double plasma experiment, tightly coupled with a 1-dimensional particle-in-cell simulation, the results presented here show that this instability is critically sensitive to the experimental conditions. Boundary effects, which do not have any counterpart in space or in most simulations, unavoidably excite parasitic instabilities. Potential fluctuations from these instabilities lead to an increase of the beam temperature which reduces the growth rate such that non-linear effects leading to solitary waves are less likely to be observed. Furthermore, the increased temperature modifies the range of beam velocities for which an ion acoustic beam plasma instability is observed.

  15. Dynamic and acoustic response of a clamped rectangular plate in thermal environments: experiment and numerical simulation.

    PubMed

    Geng, Qian; Li, Huan; Li, Yueming

    2014-05-01

    Experiments were performed to investigate the vibration and acoustic response characteristics of a clamped rectangular aluminum plate in thermal environments. Modal tests were carried out to study the influence of thermal environment on natural vibration. With the increment of structural temperature, natural frequencies of the plate decrease obviously. Mode shape interchange was observed for the modes with frequencies very close to each other. The thermally induced softening effect has unequal influences on the plate along the two in-plane directions. Numerical methods were also employed to study the experimental phenomena. Calculated results indicated that the initial deflection has a great influence on the natural vibration of the heated plate. Even a slight curvature can reduce the thermally induced softening effect obviously. Dynamic response tests were carried out under acoustic and mechanical excitations, and the measured results indicate that the variation in damping determines the response amplitudes at resonant peaks in the test. PMID:24815251

  16. Impact of ocean variability on coherent underwater acoustic communications during the Kauai [corrected] experiment (KauaiEx).

    PubMed

    Song, Aijun; Badiey, Mohsen; Song, H C; Hodgkiss, William S; Porter, Michael B

    2008-02-01

    During the July 2003 acoustic communications experiment conducted in 100 m deep water off the western side of Kauai, Hawaii, a 10 s binary phase shift keying signal with a symbol rate of 4 kilosymbol/s was transmitted every 30 min for 27 h from a bottom moored source at 12 kHz center frequency to a 16 element vertical array spanning the water column at about 3 km range. The communications signals are demodulated by time reversal multichannel combining followed by a single channel decision feedback equalizer using two subsets of array elements whose channel characteristics appear distinct: (1) top 10 and (2) bottom 4 elements. Due to rapid channel variations, continuous channel updates along with Doppler tracking are required prior to time reversal combining. This is especially true for the top 10 elements where the received acoustic field involves significant interaction with the dynamic ocean surface. The resulting communications performance in terms of output signal-to-noise ratio exhibits significant change over the 27 h transmission duration. This is particularly evident as the water column changes from well-mixed to a downward refracting environment. PMID:18273951

  17. The development of acoustic experiments for off-campus teaching and learning

    NASA Astrophysics Data System (ADS)

    Wild, Graham; Swan, Geoff

    2011-05-01

    In this article, we show the implementation of a computer-based digital storage oscilloscope (DSO) and function generator (FG) using the computer's soundcard for off-campus acoustic experiments. The microphone input is used for the DSO, and a speaker jack is used as the FG. In an effort to reduce the cost of implementing the experiment, we examine software available for free, online. A small number of applications were compared in terms of their interface and functionality, for both the DSO and the FG. The software was then used to investigate standing waves in pipes using the computer-based DSO. Standing wave theory taught in high school and in first year physics is based on a one-dimensional model. With the use of the DSO's fast Fourier transform function, the experimental uncertainly alone was not sufficient to account for the difference observed between the measure and the calculated frequencies. Hence the original experiment was expanded upon to include the end correction effect. The DSO was also used for other simple acoustics experiments, in areas such as the physics of music.

  18. 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.

  19. Two Years of Industrial Experience in the Use of a Small, Direct Field Acoustic Chamber

    NASA Astrophysics Data System (ADS)

    Saggini, Nicola; Di Pietro, Vincenzo; Poulain, Nicolas; Herzog, Philippe

    2012-07-01

    Within Thales Alenia Space - Italy small satellite Assembly Integration and Test (AIT) plant, the need to develop a suitable facility for spacecraft acoustic noise test has arisen, with additional constraints posed by the necessity of a low impact on the existing building layout, low cost of procurement and operations, while maintaining a high reliability of the system for a theoretical maximum throughput of one test per week over an extended period of time, e.g. six months. The needs have been answered by developing a small (~40 m3 test volume), direct field (DF A T) acoustic test chamber, christened “Alpha Cabin”, where noise generation is achieved by means of commercial audio drivers equipped with custom enclosures. The paper starts with a brief presentation of the main characteristics of the system, but then concentrates on the lessons learnt and return of experience from the tests conducted in more than two years of continuous use. Starting from test article structural responses and their comparison with reverberant chambers, properties of the acoustic field and their implications on the former are analyzed.

  20. Virtual adult ears reveal the roles of acoustical factors and experience in auditory space map development

    PubMed Central

    Campbell, Robert A. A.; King, Andrew J.; Nodal, Fernando R.; Schnupp, Jan W. H.; Carlile, Simon; Doubell, Timothy P.

    2009-01-01

    Auditory neurons in the superior colliculus (SC) respond preferentially to sounds from restricted directions to form a map of auditory space. The development of this representation is shaped by sensory experience, but little is known about the relative contribution of peripheral and central factors to the emergence of adult responses. By recording from the SC of anesthetized ferrets at different age points, we show that the map matures gradually after birth; the spatial receptive fields (SRFs) become more sharply tuned and topographic order emerges by the end of the second postnatal month. Principal components analysis of the head-related transfer function revealed that the time course of map development is mirrored by the maturation of the spatial cues generated by the growing head and external ears. However, using virtual acoustic space stimuli, we show that these acoustical changes are not by themselves responsible for the emergence of SC map topography. Presenting stimuli to infant ferrets through virtual adult ears did not improve the order in the representation of sound azimuth in the SC. But using linear discriminant analysis to compare different response properties across age, we found that the SRFs of infant neurons nevertheless became more adult-like when stimuli were delivered through virtual adult ears. Hence, although the emergence of auditory topography is likely to depend on refinements in neural circuitry, maturation of the structure of the SRFs (particularly their spatial extent) can be largely accounted for by changes in the acoustics associated with growth of the head and ears. PMID:18987192

  1. Virtual adult ears reveal the roles of acoustical factors and experience in auditory space map development.

    PubMed

    Campbell, Robert A A; King, Andrew J; Nodal, Fernando R; Schnupp, Jan W H; Carlile, Simon; Doubell, Timothy P

    2008-11-01

    Auditory neurons in the superior colliculus (SC) respond preferentially to sounds from restricted directions to form a map of auditory space. The development of this representation is shaped by sensory experience, but little is known about the relative contribution of peripheral and central factors to the emergence of adult responses. By recording from the SC of anesthetized ferrets at different age points, we show that the map matures gradually after birth; the spatial receptive fields (SRFs) become more sharply tuned and topographic order emerges by the end of the second postnatal month. Principal components analysis of the head-related transfer function revealed that the time course of map development is mirrored by the maturation of the spatial cues generated by the growing head and external ears. However, using virtual acoustic space stimuli, we show that these acoustical changes are not by themselves responsible for the emergence of SC map topography. Presenting stimuli to infant ferrets through virtual adult ears did not improve the order in the representation of sound azimuth in the SC. But by using linear discriminant analysis to compare different response properties across age, we found that the SRFs of infant neurons nevertheless became more adult-like when stimuli were delivered through virtual adult ears. Hence, although the emergence of auditory topography is likely to depend on refinements in neural circuitry, maturation of the structure of the SRFs (particularly their spatial extent) can be largely accounted for by changes in the acoustics associated with growth of the head and ears. PMID:18987192

  2. An undergraduate experiment demonstrating the physics of metamaterials with acoustic waves and soda cans

    NASA Astrophysics Data System (ADS)

    Wilkinson, James T.; Whitehouse, Christopher B.; Oulton, Rupert F.; Gennaro, Sylvain D.

    2016-01-01

    We describe a novel undergraduate research project that highlights the physics of metamaterials with acoustic waves and soda cans. We confirm the Helmholtz resonance nature of a single can by measuring its amplitude and phase response to a sound wave. Arranging multiple cans in arrays smaller than the wavelength, we then design an antenna that redirects sound into a preferred direction. The antenna can be thought of as a new resonator, composed of artificially engineered meta-atoms, similar to a metamaterial. These experiments are illustrative, tactile, and open ended so as to enable students to explore the physics of matter/wave interaction.

  3. Acoustic Experiment to Measure the Bulk Viscosity of Near-Critical Xenon in Microgravity

    NASA Technical Reports Server (NTRS)

    Gillis, K. A.; Shinder, I.; Moldover, M. R.; Zimmerli, G. A.

    2002-01-01

    We plan a rigorous test of the theory of dynamic scaling by accurately measuring the bulk viscosity of xenon in microgravity 50 times closer to the critical temperature T(sub c) than previous experiments. The bulk viscosity zeta (or "second viscosity" or "dilational viscosity") will be determined by measuring the attenuation length of sound alpha lambda and also measuring the frequency-dependence of the speed of sound. For these measurements, we developed a unique Helmholtz resonator and specialized electro-acoustic transducers. We describe the resonator, the transducers, their performance on Earth, and their expected performance in microgravity.

  4. Optimization of Capacitive Acoustic Resonant Sensor Using Numerical Simulation and Design of Experiment

    PubMed Central

    Haque, Rubaiyet Iftekharul; Loussert, Christophe; Sergent, Michelle; Benaben, Patrick; Boddaert, Xavier

    2015-01-01

    Optimization of the acoustic resonant sensor requires a clear understanding of how the output responses of the sensor are affected by the variation of different factors. During this work, output responses of a capacitive acoustic transducer, such as membrane displacement, quality factor, and capacitance variation, are considered to evaluate the sensor design. The six device parameters taken into consideration are membrane radius, backplate radius, cavity height, air gap, membrane tension, and membrane thickness. The effects of factors on the output responses of the transducer are investigated using an integrated methodology that combines numerical simulation and design of experiments (DOE). A series of numerical experiments are conducted to obtain output responses for different combinations of device parameters using finite element methods (FEM). Response surface method is used to identify the significant factors and to develop the empirical models for the output responses. Finally, these results are utilized to calculate the optimum device parameters using multi-criteria optimization with desirability function. Thereafter, the validating experiments are designed and deployed using the numerical simulation to crosscheck the responses. PMID:25894937

  5. Acoustic experience shapes alternative mating tactics and reproductive investment in male field crickets.

    PubMed

    Bailey, Nathan W; Gray, Brian; Zuk, Marlene

    2010-05-11

    Developmental plasticity allows juvenile animals to assess environmental cues and adaptively shape behavioral and morphological traits to maximize fitness in their adult environment. Sexual signals are particularly conspicuous cues, making them likely candidates for mediating such responses. Plasticity in male reproductive traits is a common phenomenon, but empirical evidence for signal-mediated plasticity in males is lacking. We tested whether experience of acoustic sexual signals during juvenile stages influences the development of three adult traits in the continuously breeding field cricket Teleogryllus oceanicus: male mating tactics, reproductive investment, and condition. All three traits were affected by juvenile acoustic experience. Males of this species produce a long-range calling song to attract receptive females, but they can also behave as satellites by parasitizing other males' calls. Males reared in an environment mimicking a population with many calling males were less likely to exhibit satellite behavior, invested more in reproductive tissues, and attained higher condition than males reared in a silent environment. These results contrast with other studies and demonstrate how the effects of juvenile social experience on adult male morphology, reproductive investment, and behavior may subsequently influence sexual selection and phenotypic evolution. PMID:20417103

  6. Optimization of capacitive acoustic resonant sensor using numerical simulation and design of experiment.

    PubMed

    Haque, Rubaiyet Iftekharul; Loussert, Christophe; Sergent, Michelle; Benaben, Patrick; Boddaert, Xavier

    2015-01-01

    Optimization of the acoustic resonant sensor requires a clear understanding of how the output responses of the sensor are affected by the variation of different factors. During this work, output responses of a capacitive acoustic transducer, such as membrane displacement, quality factor, and capacitance variation, are considered to evaluate the sensor design. The six device parameters taken into consideration are membrane radius, backplate radius, cavity height, air gap, membrane tension, and membrane thickness. The effects of factors on the output responses of the transducer are investigated using an integrated methodology that combines numerical simulation and design of experiments (DOE). A series of numerical experiments are conducted to obtain output responses for different combinations of device parameters using finite element methods (FEM). Response surface method is used to identify the significant factors and to develop the empirical models for the output responses. Finally, these results are utilized to calculate the optimum device parameters using multi-criteria optimization with desirability function. Thereafter, the validating experiments are designed and deployed using the numerical simulation to crosscheck the responses. PMID:25894937

  7. Generation of Artificial Acoustic-Gravity Waves and Traveling Ionospheric Disturbances in HF Heating Experiments

    NASA Astrophysics Data System (ADS)

    Pradipta, R.; Lee, M. C.; Cohen, J. A.; Watkins, B. J.

    2015-10-01

    We report the results of our ionospheric HF heating experiments to generate artificial acoustic-gravity waves (AGW) and traveling ionospheric disturbances (TID), which were conducted at the High-frequency Active Auroral Research Program facility in Gakona, Alaska. Based on the data from UHF radar, GPS total electron content, and ionosonde measurements, we found that artificial AGW/TID can be generated in ionospheric modification experiments by sinusoidally modulating the power envelope of the transmitted O-mode HF heater waves. In this case, the modulation frequency needs to be set below the characteristic Brunt-Vaisala frequency at the relevant altitudes. We avoided potential contamination from naturally-occurring AGW/TID of auroral origin by conducting the experiments during geomagnetically quiet time period. We determine that these artificial AGW/TID propagate away from the edge of the heated region with a horizontal speed of approximately 160 m/s.

  8. Spectral Characteristics of Continuous Acoustic Emission (AE) Data from Laboratory Rock Deformation Experiments

    NASA Astrophysics Data System (ADS)

    Flynn, J. William; Goodfellow, Sebastian; Reyes-Montes, Juan; Nasseri, Farzine; Young, R. Paul

    2016-04-01

    Continuous acoustic emission (AE) data recorded during rock deformation tests facilitates the monitoring of fracture initiation and propagation due to applied stress changes. Changes in the frequency and energy content of AE waveforms have been previously observed and were associated with microcrack coalescence and the induction or mobilisation of large fractures which are naturally associated with larger amplitude AE events and lower-frequency components. The shift from high to low dominant frequency components during the late stages of the deformation experiment, as the rate of AE events increases and the sample approaches failure, indicates a transition from the micro-cracking to macro-cracking regime, where large cracks generated result in material failure. The objective of this study is to extract information on the fracturing process from the acoustic records around sample failure, where the fast occurrence of AE events does not allow for identification of individual AE events and phase arrivals. Standard AE event processing techniques are not suitable for extracting this information at these stages. Instead the observed changes in the frequency content of the continuous record can be used to characterise and investigate the fracture process at the stage of microcrack coalescence and sample failure. To analyse and characterise these changes, a detailed non-linear and non-stationary time-frequency analysis of the continuous waveform data is required. Empirical Mode Decomposition (EMD) and Hilbert Spectral Analysis (HSA) are two of the techniques used in this paper to analyse the acoustic records which provide a high-resolution temporal frequency distribution of the data. In this paper we present the results from our analysis of continuous AE data recorded during a laboratory triaxial deformation experiment using the combined EMD and HSA method.

  9. Comprehensive comparisons of geodesic acoustic mode characteristics and dynamics between Tore Supra experiments and gyrokinetic simulations

    SciTech Connect

    Storelli, A. Vermare, L.; Hennequin, P.; Gürcan, Ö. D.; Singh, Rameswar; Morel, P.; Dif-Pradalier, G.; Sarazin, Y.; Garbet, X.; Grandgirard, V.; Ghendrih, P.; Görler, T.

    2015-06-15

    In a dedicated collisionality scan in Tore Supra, the geodesic acoustic mode (GAM) is detected and identified with the Doppler backscattering technique. Observations are compared to the results of a simulation with the gyrokinetic code GYSELA. We found that the GAM frequency in experiments is lower than predicted by simulation and theory. Moreover, the disagreement is higher in the low collisionality scenario. Bursts of non harmonic GAM oscillations have been characterized with filtering techniques, such as the Hilbert-Huang transform. When comparing this dynamical behaviour between experiments and simulation, the probability density function of GAM amplitude and the burst autocorrelation time are found to be remarkably similar. In the simulation, where the radial profile of GAM frequency is continuous, we observed a phenomenon of radial phase mixing of the GAM oscillations, which could influence the burst autocorrelation time.

  10. Results From a Parametric Acoustic Liner Experiment Using P and W GEN1 HSR Mixer/Ejector Model

    NASA Technical Reports Server (NTRS)

    Boyd, Kathleen C.; Wolter, John D.

    2004-01-01

    This report documents the results of an acoustic liner test performed using a Gen 1 HSR mixer/ejector model installed on the Jet Exit Rig in the Nozzle Acoustic Test Rig in the Aeroacoustic Propulsion Laboratory or NASA Glenn Research Center. Acoustic liner effectiveness and single-component thrust performance results are discussed. Results from 26 different types of single-degree-of-freedom and bulk material liners are compared with each other and against a hardwall baseline. Design parameters involving all aspects of the facesheet, the backing cavity, and the type of bulk material were varied in order to study the effects of these design features on the acoustic impedance, acoustic effectiveness and on nozzle thrust performance. Overall, the bulk absorber liners are more effective at reducing the jet noise than the single-degree-of-freedom liners. Many of the design parameters had little effect on acoustic effectiveness, such as facesheeet hole diameter and honeycomb cell size. A relatively large variation in the impedance of the bulk absorber in a bulk liner is required to have a significant impact on the noise reduction. The thrust results exhibit a number of consistent trends, supporting the validity of this new addition to the facility. In general, the thrust results indicate that thrust performance benefits from increased facesheet thickness and decreased facesheet porosity.

  11. Producing ion waves from acoustic pressure waves in pulsed ICP: Modeling vs. Experiments

    NASA Astrophysics Data System (ADS)

    Despiau-Pujo, Emilie; Cunge, Gilles; Darnon, Maxime; Sadeghi, Nader; Braithwaite, Nicholas

    2015-09-01

    Neutral depletion is an important phenomenon in CW high-density plasmas, mostly caused by gas heating - with a small contribution due to electron pressure Pe - under typical material processing conditions. In pulsed ICP, neutral depletion plays an important role on radical transport in the afterglow. At the beginning of the afterglow, Pe drops rapidly (10 μs) by electron cooling and the gas cools down as well. It generates a neutral pressure gradient between the plasma bulk and the reactor walls, which in turn forces the cold surrounding gas to move rapidly towards the center, thus launching an acoustic wave in the reactor. Fast gas displacement is evidenced by measuring Al atoms drift velocity in the early afterglow of a Cl2/Ar discharge by time-resolved LIF, the acoustic wave in the chamber being observed by mass spectrometry. 2D fluid simulations of Cl2 pulsed ICP predict similar results. These phenomena are further studied during both the plasma ignition and afterglow using modeling and experiments. Strong oscillations are observed both on the Cl2 neutral densities and on the ion flux. As neutrals are pushed towards (or outwards) the chamber walls by the pressure gradient, ions are also pushed in that direction through collisions, as well captured by our ion flux probe.

  12. Ultrasonic power transfer from a spherical acoustic wave source to a free-free piezoelectric receiver: Modeling and experiment

    NASA Astrophysics Data System (ADS)

    Shahab, S.; Gray, M.; Erturk, A.

    2015-03-01

    Contactless powering of small electronic components has lately received growing attention for wireless applications in which battery replacement or tethered charging is undesired or simply impossible, and ambient energy harvesting is not a viable solution. As an alternative to well-studied methods of contactless energy transfer, such as the inductive coupling method, the use of ultrasonic waves transmitted and received by piezoelectric devices enables larger power transmission distances, which is critical especially for deep-implanted electronic devices. Moreover, energy transfer by means of acoustic waves is well suited in situations where no electromagnetic fields are allowed. The limited literature of ultrasonic acoustic energy transfer is mainly centered on proof-of-concept experiments demonstrating the feasibility of this method, lacking experimentally validated modeling efforts for the resulting multiphysics problem that couples the source and receiver dynamics with domain acoustics. In this work, we present fully coupled analytical, numerical, and experimental multiphysics investigations for ultrasonic acoustic energy transfer from a spherical wave source to a piezoelectric receiver bar that operates in the 33-mode of piezoelectricity. The fluid-loaded piezoelectric receiver under free-free mechanical boundary conditions is shunted to an electrical load for quantifying the electrical power output for a given acoustic source strength of the transmitter. The analytical acoustic-piezoelectric structure interaction modeling framework is validated experimentally, and the effects of system parameters are reported along with optimal electrical loading and frequency conditions of the receiver.

  13. Ultrasonic power transfer from a spherical acoustic wave source to a free-free piezoelectric receiver: Modeling and experiment

    SciTech Connect

    Shahab, S.; Gray, M.; Erturk, A.

    2015-03-14

    Contactless powering of small electronic components has lately received growing attention for wireless applications in which battery replacement or tethered charging is undesired or simply impossible, and ambient energy harvesting is not a viable solution. As an alternative to well-studied methods of contactless energy transfer, such as the inductive coupling method, the use of ultrasonic waves transmitted and received by piezoelectric devices enables larger power transmission distances, which is critical especially for deep-implanted electronic devices. Moreover, energy transfer by means of acoustic waves is well suited in situations where no electromagnetic fields are allowed. The limited literature of ultrasonic acoustic energy transfer is mainly centered on proof-of-concept experiments demonstrating the feasibility of this method, lacking experimentally validated modeling efforts for the resulting multiphysics problem that couples the source and receiver dynamics with domain acoustics. In this work, we present fully coupled analytical, numerical, and experimental multiphysics investigations for ultrasonic acoustic energy transfer from a spherical wave source to a piezoelectric receiver bar that operates in the 33-mode of piezoelectricity. The fluid-loaded piezoelectric receiver under free-free mechanical boundary conditions is shunted to an electrical load for quantifying the electrical power output for a given acoustic source strength of the transmitter. The analytical acoustic-piezoelectric structure interaction modeling framework is validated experimentally, and the effects of system parameters are reported along with optimal electrical loading and frequency conditions of the receiver.

  14. State public policy issues involved with the Parkfield prediction experiment.

    USGS Publications Warehouse

    Andrews, R.; Goltz, J.

    1988-01-01

    The earthquake-prediction experiment at Parkfield may well be the most important such experiment currently underway worldwide. Its importance, however, extends beyond the scientific data that will be gathered and whether those data that will be gathered and whether those data can provide reliable prediction methods. Important public policy lessons are being learned (and are yet to be learned), and these lessons may be transferable to other parts of California and the nation. Indeed, the Parkfield experiment has captured the interest of numerous Californians, including State officials, emergency managers, the news media, and at least some of the public.

  15. Student Involvement and the Psychological Experience of the High School.

    ERIC Educational Resources Information Center

    Nover, Michael L.

    The role of the school in the fostering of competence and psychological well-being in students is of primary concern to school psychologists. Adolescents' involvement in high school extracurricular activities was examined to determine their effect on socialization and possible relationships with demographic patterns and high school performance. A…

  16. Janshala in Jharkhand: An Experiment with Community Involvement in Education

    ERIC Educational Resources Information Center

    Pailwar, Veena K.; Mahajan, Vandana

    2005-01-01

    Education has been identified as one of the primary agents of transformation towards development. However, low level of literacy and education is one of the major challenges facing most of the underdeveloped countries. Active community involvement and participation has emerged as an effective mechanism in improving the sustainable level of…

  17. EFFECT OF AGE AND EXPERIENCE ON INHIBITION OF THE ACOUSTIC STARTLE RESPONSE BY GAPS IN BACKGROUND NOISE

    EPA Science Inventory

    The acoustic startle response (ASR) is inhibited when the eliciting stimulus is preceded by a brief gap in background noise. he present study bed the ontogeny of ASR gap inhibition in the rat and the role of experience on its development. ndependent groups of Long-Evans rats were...

  18. Acoustic resonances of fluid-immersed elastic cylinders and spheroids: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Niemiec, Jan; Überall, Herbert; Bao, X. L.

    2002-05-01

    Frequency resonances in the scattering of acoustic waves from a target object are caused by the phase matching of surface waves repeatedly encircling the object. This is exemplified here by considering elastic finite cylinders and spheroids, and the phase-matching condition provides a means of calculating the complex resonance frequencies of such objects. Tank experiments carried out at Catholic University, or at the University of Le Havre, France by G. Maze and J. Ripoche, have been interpreted using this approach. The experiments employed sound pulses to measure arrival times, which allowed identification of the surface paths taken by the surface waves, thus giving rise to resonances in the scattering amplitude. A calculation of the resonance frequencies using the T-matrix approach showed satisfactory agreement with the experimental resonance frequencies that were either measured directly (as at Le Havre), or that were obtained by the interpretation of measured arrival times (at Catholic University) using calculated surface wave paths, and the extraction of resonance frequencies therefrom, on the basis of the phase-matching condition. Results for hemispherically endcapped, evacuated steel cylinders obtained in a lake experiment carried out by the NSWC were interpreted in the same fashion.

  19. Role of transient water pressure in quarrying: A subglacial experiment using acoustic emissions

    USGS Publications Warehouse

    Cohen, D.; Hooyer, T.S.; Iverson, N.R.; Thomason, J.F.; Jackson, M.

    2006-01-01

    Probably the most important mechanism of glacial erosion is quarrying: the growth and coalescence of cracks in subglacial bedrock and dislodgement of resultant rock fragments. Although evidence indicates that erosion rates depend on sliding speed, rates of crack growth in bedrock may be enhanced by changing stresses on the bed caused by fluctuating basal water pressure in zones of ice-bed separation. To study quarrying in real time, a granite step, 12 cm high with a crack in its stoss surface, was installed at the bed of Engabreen, Norway. Acoustic emission sensors monitored crack growth events in the step as ice slid over it. Vertical stresses, water pressure, and cavity height in the lee of the step were also measured. Water was pumped to the lee of the step several times over 8 days. Pumping initially caused opening of a leeward cavity, which then closed after pumping was stopped and water pressure decreased. During cavity closure, acoustic emissions emanating mostly from the vicinity of the base of the crack in the step increased dramatically. With repeated pump tests this crack grew with time until the step's lee surface was quarried. Our experiments indicate that fluctuating water pressure caused stress thresholds required for crack growth to be exceeded. Natural basal water pressure fluctuations should also concentrate stresses on rock steps, increasing rates of crack growth. Stress changes on the bed due to water pressure fluctuations will increase in magnitude and duration with cavity size, which may help explain the effect of sliding speed on erosion rates. Copyright 2006 by the American Geophysical Union.

  20. Effect of gas adsorption on acoustic wave propagation in MFI zeolite membrane materials: experiment and molecular simulation.

    PubMed

    Manga, Etoungh D; Blasco, Hugues; Da-Costa, Philippe; Drobek, Martin; Ayral, André; Le Clezio, Emmanuel; Despaux, Gilles; Coasne, Benoit; Julbe, Anne

    2014-09-01

    The present study reports on the development of a characterization method of porous membrane materials which consists of considering their acoustic properties upon gas adsorption. Using acoustic microscopy experiments and atomistic molecular simulations for helium adsorbed in a silicalite-1 zeolite membrane layer, we showed that acoustic wave propagation could be used, in principle, for controlling the membranes operando. Molecular simulations, which were found to fit experimental data, showed that the compressional modulus of the composite system consisting of silicalite-1 with adsorbed He increases linearly with the He adsorbed amount while its shear modulus remains constant in a large range of applied pressures. These results suggest that the longitudinal and Rayleigh wave velocities (VL and VR) depend on the He adsorbed amount whereas the transverse wave velocity VT remains constant. PMID:25089584

  1. Shipboard acoustic doppler current profiler data collected during the Western Tropical Atlantic Experiment (WESTRAX) 1991. Technical memo

    SciTech Connect

    Routt, J.A.; Wilson, W.D.

    1992-11-01

    The long-term goal of ongoing and future research in the western tropical Atlantic is to estimate the cross-equatorial transport of water and heat. The overall goals of those involved in the Western Tropical Atlantic Experiment (WESTRAX) are (a) to describe the annual cycle in the large-scale structure of the velocity and hydrographic properties over the full water column in the western tropical Atlantic Ocean between the equator and 15 degrees N, and (b) to compare data and models in order to better understand the physics of the regional circulation in the broader context of Atlantic basin thermohaline circulation. The results of this combined effort will greatly improve our understanding of this complex boundary current region and establish the basis for efficient long-term climatic monitoring of the critical meridional fluxes of mass and heat across the tropical Atlantic. This report presents the Acoustic Doppler Current Profiler (ADCP) data obtained during (ACCP) Atlantic Climate Change Program cruises in the western subtropical and tropical Atlantic in January, June and September 1991.

  2. Surface science experiments involving the atomic force microscope

    NASA Astrophysics Data System (ADS)

    McBride, Sean P.

    Three diverse first author surfaces science experiments conducted by Sean P. McBride1-3 will be discussed in detail and supplemented by secondary co-author projects by Sean P. McBride,4-7 all of which rely heavily on the use of an atomic force microscope (AFM). First, the slip length parameter, b of liquids is investigated using colloidal probe AFM. The slip length describes how easily a fluid flows over an interface. The slip length, with its exact origin unknown and dependencies not overwhelming decided upon by the scientific community, remains a controversial topic. Colloidal probe AFM uses a spherical probe attached to a standard AFM imaging tip driven through a liquid. With the force on this colloidal AFM probe known, and using the simplest homologous series of test liquids, many of the suspected causes and dependencies of the slip length demonstrated in the literature can be suppressed or eliminated. This leaves the measurable trends in the slip length attributed only to the systematically varying physical properties of the different liquids. When conducting these experiments, it was realized that the spring constant, k, of the system depends upon the cantilever geometry of the experiment and therefore should be measured in-situ. This means that the k calibration needs to be performed in the same viscous liquid in which the slip experiments are performed. Current in-situ calibrations in viscous fluids are very limited, thus a new in-situ k calibration method was developed for use in viscous fluids. This new method is based upon the residuals, namely, the difference between experimental force-distance data and Vinogradova slip theory. Next, the AFM's ability to acquire accurate sub nanometer height profiles of structures on interfaces was used to develop a novel experimental technique to measure the line tension parameter, tau, of isolated nanoparticles at the three phase interface in a solid-liquid-vapor system. The tau parameter is a result of excess energy

  3. Model-based processor design for a shallow water ocean acoustic experiment

    SciTech Connect

    Candy, J.V. ); Sullivan, E.J. )

    1994-04-01

    Model-based signal processing is a well-defined methodology enabling the inclusion of environmental (propagation) models, measurement (sensor arrays) models, and noise (shipping, measurement) models into a sophisticated processing algorithm. Depending on the class of model developed from the mathematical representation of the physical phenomenology, various processors can evolve. Here the design of a space-varying, nonstationary, model-based processor (MBP) is investigated and applied to the data from a well-controlled shallow water experiment performed at Hudson Canyon. This particular experiment is very attractive for the inaugural application of the MBP because it was performed in shallow water at low frequency requiring a small number of modes. In essence, the Hudson Canyon represents a well-known ocean environment, making it ideal for this investigation. In this shallow water application, a state-space representation of the normal-mode propagation model is used. The processor is designed such that it allows [ital in] [ital situ] recursive estimation of both the pressure-field and modal functions. It is shown that the MBP can be effectively utilized to validate'' the performance of the model on noisy ocean acoustic data. In fact, a set of processors is designed, one for each source range and the results are quite good---implying that the propagation model with measured parameters adequately represents the data.

  4. Structural instabilities involving time dependent materials : theory and experiment

    NASA Astrophysics Data System (ADS)

    Minahen, Timothy M.

    The creep buckling of viscoelastic structures is studied analytically and experimentally to investigate structural stability in the presence of time dependent materials. The theory of linear viscoelasticity is used to model polymeric column specimens subjected to constant compressive end loads. A strength of materials approach (Euler-Bernoulli beam theory) is employed to model the moment-curvature relation for the column. The growth of initial imperfections is calculated using the hereditary integral formulation. Solution techniques are developed for small displacements and then generalized to include the effects of large displacements and rotations. A failure criterion based on maximum deformation allows the column life to be estimated directly from the material relaxation modulus. A discussion generalizing the results to include plates and shells is presented.Rectangular cross-section polymethylmethacrylate (PMMA) specimens with hinged boundary conditions are used to study viscoelastic buckling experimentally. Constant compressive end loads are applied using a servo-controlled load frame while the specimens are kept in a temperature cabinet at elevated temperatures (accelerating the creep behavior). Specimen shortening and out-of-plane deflections are monitored during the tests. The relaxation modulus of PMMA is approximated by a Prony-Dirichlet series and the model is used to simulate the laboratory experiments. Model and experimental results show good agreement during the "glassy" and slow growth phases of the column response. As the growth rate increases some deviations between theory and experiment are seen. It is shown that the deviations are not a result of geometric nonlinearities, but may, in part, be explained by material nonlinearities not accounted for in the model.

  5. Multibiological life support system experiments with humans partially involved

    NASA Astrophysics Data System (ADS)

    Liu, Hong; Tong, Ling; Li, Ming; Hu, Dawei; Fu, Yuming; He, Wenting; Hu, Enzhu

    To establish bioregenerative life support system in lunar or mars bases in the future, manned stimulation experiments including several kinds of creatures are needed to be conducted first. Gas exchange relation, element transfer and transformation principles, etc. between human beings and the multibiological system composed of plants, animals, Chlorella vulgaris and so on must be investigated in order to place different organisms with appropriate numbers and proportions. This research cultivated lettuce (Lactuca sativa L.) and silkworm (Bombyx Mori L.) in the Closed Integrative Cultivating System (CICS) of the Integrative Experimental Sys-tem (IES) with Chlorella vulgaris cultivated in the Plate Photo Bioreactor (PPB) of the IES. Gas exchange between testers and the IES were conducted periodically. The automotive control system of the PPB changed the illumination intensity of the photo bioreactor according to the CO2 concentration in the IES to make CO2 /O2 in the system maintain at stable levels by regu-lating the photosynthesis of alga. The conveyor-type cultivation method which was harvesting the biggest batch of lettuce and silkworms through the mass exchange chamber of IES every four days and transferring the smallest batch of lettuce and silkworms into the system; carrying certain amount of alga liquid out of the bioreactor every day with nutrient liquid replenished into the system was implemented in the experiments. In terms of gas circulation, CO2 /O2 concentration changes in the system with trace gas contaminants (CH4 , NH3 and C2 H4 ) were measured. As to the mass transfer and transformation, element (C, H, O, N) contents, height, crown width and biomasses of lettuce in different developing stages, silkworms' bioconversion rates, alga's biomass changes, the amount and community change trends of the microorganism in different positions of the system, the quality of condensates gained under different running conditions and so on were studied. Results showed

  6. Characterization of blocks impacts from acoustic emissions: insights from laboratory experiments

    NASA Astrophysics Data System (ADS)

    Farin, Maxime; Mangeney, Anne; de Rosny, Julien; Toussaint, Renaud; Shapiro, Nikolaï

    2014-05-01

    Rockfalls, debris flows and rock avalanches represent a major natural hazard for the population in mountainous, volcanic and coastal areas but their direct observation on the field is very dangerous. Recent studies showed that gravitational instabilities can be detected and characterized (volume, duration,...) thanks to the seismic signal they generate. In an avalanche, individual block bouncing and rolling on the ground are expected to generated signals of higher frequencies than the main flow spreading. The identification of the time/frequency signature of individual blocks in the recorded signal remains however difficult. Laboratory experiments were conducted to investigate the acoustic signature of diverse simple sources corresponding to grains falling over thin plates of plexiglas and glass and over rock blocks. The elastic energy emitted by a single bouncing bead into the support was first quantitatively estimated and compared to the potential energy of fall and to the potential energy change during the shock. We obtained simple scaling laws relating the impactor characteristics (size, height of fall, material,...) to the elastic energy and spectral content. Next, we consider the collapse of granular columns made of steel spherical beads onto hard substrates. Initially, these columns were held by a magnetic field allowing to suppress suddenly the cohesion between the beads, and thus to minimize friction effects that would arise from side walls. We varied systematically the column volume, the column aspect ratio (height over length) and the grain size. This is shown to affect the signal envelope and frequency content. In the experiments, accelerometers (1 Hz to 56 kHz) were used to record the signals in a wide frequency range. The experiments were also monitored optically using fast cameras. Eventually, we looked at what types of features in the signal are affected by individual impacts, rolling of beads or by the large scale geometry of the avalanche.

  7. The Chemistry Involved in the Preparation of a Paint Pigment: An Experiment for the Freshman Laboratory

    ERIC Educational Resources Information Center

    Daines, Terri L.; Morse, Karen W.

    1976-01-01

    Describes an experiment that demonstrates the following principles and reactions: amphoterism, oxidation-reduction, equilibrium dependence on pH, solubility, and polymerization. The experiment involves the oxidation of chromium and the precipitation of a chromate salt. (MLH)

  8. An innovative acoustic sensor for first in-pile fission gas release determination - REMORA 3 experiment

    SciTech Connect

    Rosenkrantz, E.; Ferrandis, J. Y.; Augereau, F.; Lambert, T.; Fourmentel, D.; Tiratay, X.

    2011-07-01

    A fuel rod has been instrumented with a new design of an acoustic resonator used to measure in a non destructive way the internal rod plenum gas mixture composition. This ultrasonic sensor has demonstrated its ability to operate in pile during REMORA 3 irradiation experiment carried out in the OSIRIS Material Testing Reactor (CEA Saclay, France). Due to very severe experimental conditions such as temperature rising up to 150 deg.C and especially, high thermal fluence level up to 3.5 10{sup 19} n.cm{sup 2}, the initial sensor gas speed of sound efficiency measurement was strongly reduced due to the irradiation effects on the piezo-ceramic properties. Nevertheless, by adding a differential signal processing method to the initial data analysis procedure validated before irradiation, the gas resonance peaks were successfully extracted from the output signal. From these data, the molar fractions variations of helium and fission gas were measured from an adapted Virial state equation. Thus, with this sensor, the kinetics of gas release inside fuel rods could be deduced from the in-pile measurements and specific calculations. These data will also give information about nuclear reaction effect on piezo-ceramics sensor under high neutron and gamma flux. (authors)

  9. Identifying co-located acoustic emissions with highly correlated waveforms during stick-slip experiments

    NASA Astrophysics Data System (ADS)

    Goebel, T. H.; Zechar, J. D.; Becker, T. W.; Dresen, G. H.

    2012-12-01

    Repeating earthquakes, which may result from the repeated failure of strong fault patches, could help advance the understanding of structural differences of faults. They also provide a framework to test basic assumptions in earthquake physics and to quantify earthquake predictability. Our current efforts concentrate on a broadening of the understanding of micro-seismicity characteristics and its relation to fault structure and larger magnitude seismic events. In this study, we consider the possibly smallest repeating earthquakes: those generated in a laboratory setting. We present results from stick-slip experiments conducted on saw-cut surfaces with different roughness. During these tests we identified repeating acoustic emissions (AEs), i.e, largely co-located AEs with highly similar waveforms, and relate them to the difference in roughness of a particular surfaces. For these test we used three homogeneous Westerly granite cores that were pre-cut at a 30 degree angle to the loading axis. The saw-cuts were ground to be largely parallel and to create a specific roughness using silicon-carbide abrasives with different grain-sizes. We loaded the so prepared surfaces axially at a confining pressure of 120 to 150 MPa until several (up to 7) stick-slips occurred and recorded mechanical data and AEs, including full waveforms. AE locations were determined using automatically-picked first-arrival times of a 14 channel miniature seismic array. The location uncertainty was between 1-4 mm. In identifying repeating AEs, we conducted a systematic sensitivity analysis. Initially, we only imposed constrains on waveforms similarity and tested the influence of distance-constrains on the identification process. For a more restrictive choice of cross-correlation coefficient and correlation windows, the size of clusters did not grow above twice the approximate uncertainties of acoustic emission locations. Thus, repeating AEs identified with our algorithm are representative of tectonic

  10. Experiments on the acoustic solitary wave generated thermoacoustically in a looped tube

    NASA Astrophysics Data System (ADS)

    Shimizu, Dai; Sugimoto, Nobumasa

    2015-10-01

    Emergence of an acoustic solitary wave is demonstrated in a gas-filled, looped tube with an array of Helmholtz resonators connected. The solitary wave is generated thermoacoustically and spontaneously by a pair of stacks positioned diametrically on exactly the opposite side of the loop. The temperature gradient is imposed on both stacks in the same sense along the tube. The stacks made of ceramics and of many square pores are sandwiched by hot and cold heat exchangers. The pressure profile measured and the propagation speed show good agreements with the theoretical ones of the acoustic solitary wave obtained by Sugimoto (J. Acoust. Soc. Am., 99, 1971-1976 (1996)).

  11. Effect of Anisotropic Velocity Structure on Acoustic Emission Source Location during True-Triaxial Deformation Experiments

    NASA Astrophysics Data System (ADS)

    Ghofrani Tabari, Mehdi; Goodfellow, Sebastian; Young, R. Paul

    2016-04-01

    Although true-triaxial testing (TTT) of rocks is now more extensive worldwide, stress-induced heterogeneity due to the existence of several loading boundary effects is not usually accounted for and simplified anisotropic models are used. This study focuses on the enhanced anisotropic velocity structure to improve acoustic emission (AE) analysis for an enhanced interpretation of induced fracturing. Data from a TTT on a cubic sample of Fontainebleau sandstone is used in this study to evaluate the methodology. At different stages of the experiment the True-Triaxial Geophysical Imaging Cell (TTGIC), armed with an ultrasonic and AE monitoring system, performed several velocity surveys to image velocity structure of the sample. Going beyond a hydrostatic stress state (poro-elastic phase), the rock sample went through a non-dilatational elastic phase, a dilatational non-damaging elasto-plastic phase containing initial AE activity and finally a dilatational and damaging elasto-plastic phase up to the failure point. The experiment was divided into these phases based on the information obtained from strain, velocity and AE streaming data. Analysis of the ultrasonic velocity survey data discovered that a homogeneous anisotropic core in the center of the sample is formed with ellipsoidal symmetry under the standard polyaxial setup. Location of the transducer shots were improved by implementation of different velocity models for the sample starting from isotropic and homogeneous models going toward anisotropic and heterogeneous models. The transducer shot locations showed a major improvement after the velocity model corrections had been applied especially at the final phase of the experiment. This location improvement validated our velocity model at the final phase of the experiment consisting lower-velocity zones bearing partially saturated fractures. The ellipsoidal anisotropic velocity model was also verified at the core of the cubic rock specimen by AE event location of

  12. Acoustic flight test experience with the XV-15 Tiltrotor aircraft with the Advanced Technology Blade (ATB)

    NASA Technical Reports Server (NTRS)

    Hoad, Danny R.; Conner, David A.; Rutledge, Charles K.

    1992-01-01

    An acoustic model that predicts the discrete frequency noise characteristics of helicopter rotors has been utilized in an analysis to help identify source characteristics. This technique incorporated a NASA Langley developed acoustic prediction technique, and a simplified flow field model to account for rotor wake reingestion in hover. The vehicle rotor system was modified to include the ATBs that were designed to provide for higher operating weights and improved maneuver load factor in helicopter and transition modes of operation.

  13. Numerical Experiments on Acoustic Reciprocity in Compressible Potential Flows in Ducts

    NASA Astrophysics Data System (ADS)

    EVERSMAN, W.

    2001-09-01

    A reciprocity theorem for the scattering matrix for the propagation of acoustic modes in a duct with acoustically hard walls or with acoustically absorbing walls has been given in a companion publication. It was found that for a source at a specified end of the duct, suitably scaled reflection matrices in direct and reverse flow have a reciprocal relationship. Scaled transmission matrices obtained for direct flow and reversed flow with simultaneous switching of source location from one end to the other also have a reciprocal relationship. A reverse flow theorem for the equivalent one-dimensional propagation model, which is a good approximation to the three-dimensional model at low frequencies, was also obtained. In this case, using reciprocity and acoustic power conservation arguments it is additionally found that the acoustic power transmission coefficient is the same for a source at either end of the duct for a given flow direction. This result leads to an invariance theorem which relates acoustic power propagated due to sources of equal pressure amplitude at the two ends of the duct. A numerical verification of these reciprocal relationships is given here for propagation in axially symmetric (circular and annular) ducts with multi-modal propagation and at low frequencies when a one-dimensional model is appropriate.

  14. PoroTomo Subtask 3.2 Data files from the Distributed Acoustic Sensing experiment at Garner Valley, California

    DOE Data Explorer

    Chelsea Lancelle

    2013-09-11

    In September 2013, an experiment using Distributed Acoustic Sensing (DAS) was conducted at Garner Valley, a test site of the University of California Santa Barbara (Lancelle et al., 2014). This submission includes all DAS data recorded during the experiment. The sampling rate for all files is 1000 samples per second. Any files with the same filename but ending in _01, _02, etc. represent sequential files from the same test. Locations of the sources are plotted on the basemap in GDR submission 481, titled: "PoroTomo Subtask 3.2 Sample data from a Distributed Acoustic Sensing experiment at Garner Valley, California (PoroTomo Subtask 3.2)." Lancelle, C., N. Lord, H. Wang, D. Fratta, R. Nigbor, A. Chalari, R. Karaulanov, J. Baldwin, and E. Castongia (2014), Directivity and Sensitivity of Fiber-Optic Cable Measuring Ground Motion using a Distributed Acoustic Sensing Array (abstract # NS31C-3935), AGU Fall Meeting. 
https://agu.confex.com/agu/fm1/meetingapp.cgi#Paper/19828 The e-poster is available at: https://agu.confex.com/data/handout/agu/fm14/Paper_19828_handout_696_0.pdf

  15. On boundary conditions for the diffusion equation in room-acoustic prediction: Theory, simulations, and experiments.

    PubMed

    Jing, Yun; Xiang, Ning

    2008-01-01

    This paper proposes a modified boundary condition to improve the room-acoustic prediction accuracy of a diffusion equation model. Previous boundary conditions for the diffusion equation model have certain limitations which restrict its application to a certain number of room types. The boundary condition employing the Sabine absorption coefficient [V. Valeau et al., J. Acoust. Soc. Am. 119, 1504-1513 (2006)] cannot predict the sound field well when the absorption coefficient is high, while the boundary condition employing the Eyring absorption coefficient [Y. Jing and N. Xiang, J. Acoust. Soc. Am. 121, 3284-3287 (2007); A. Billon et al., Appl. Acoust. 69, (2008)] has a singularity whenever any surface material has an absorption coefficient of 1.0. The modified boundary condition is derived based on an analogy between sound propagation and light propagation. Simulated and experimental data are compared to verify the modified boundary condition in terms of room-acoustic parameter prediction. The results of this comparison suggest that the modified boundary condition is valid for a range of absorption coefficient values and successfully eliminates the singularity problem. PMID:18177146

  16. Investigation of acoustic gravity waves created by anomalous heat sources: experiments and theoretical analysis

    NASA Astrophysics Data System (ADS)

    Pradipta, R.; Lee, M. C.

    2013-07-01

    We have been investigating high-power radio wave-induced acoustic gravity waves (AGWs) at Gakona, Alaska, using the High-frequency Active Aurora Research Program (HAARP) heating facility (i.e. HF heater) and extensive diagnostic instruments. This work was aimed at performing a controlled study of the space plasma turbulence triggered by the AGWs originating from anomalous heat sources, as observed in our earlier experiments at Arecibo, Puerto Rico (Pradipta 2007 MS Thesis MIT Press, Cambridge, MA). The HF heater operated in continuous wave (CW) O-mode can heat ionospheric plasmas effectively to yield a depleted magnetic flux tube as rising plasma bubbles (Lee et al 1998 Geophys. Res. Lett. 25 579). Two processes are responsible for the depletion of the magnetic flux tube: (i) thermal expansion and (ii) chemical reactions caused by heated ions. The depleted plasmas create large density gradients that can augment spread F processes via generalized Rayleigh-Taylor instabilities (Lee et al 1999 Geophys. Res. Lett. 26 37). It is thus expected that the temperature of neutral particles in the heated ionospheric region can be increased. Such a heat source in the neutral atmosphere may potentially generate AGWs in the form of traveling ionospheric plasma disturbances (TIPDs). We should point out that these TIPDs have features distinctively different from electric and magnetic field (ExB) drifts of HF wave-induced large-scale non-propagating plasma structures. Moreover, it was noted in our recent study of naturally occurring AGW-induced TIDs that only large-scale AGWs can propagate upward to reach higher altitudes. Thus, in our Gakona experiments we select optimum heating schemes for HF wave-induced AGWs that can be distinguished from the naturally occurring ones. The generation and propagation of AGWs are monitored by MUIR (Modular Ultra high-frequency Ionospheric Radar), Digisonde and GPS/low-earth-orbit satellites. Our theoretical and experimental studies have shown that

  17. Sample data from a Distributed Acoustic Sensing experiment at Garner Valley, California (PoroTomo Subtask 3.2)

    DOE Data Explorer

    Chelsea Lancelle

    2013-09-10

    In September 2013, an experiment using Distributed Acoustic Sensing (DAS) was conducted at Garner Valley, a test site of the University of California Santa Barbara (Lancelle et al., 2014). This submission includes one 45 kN shear shaker (called “large shaker” on the basemap) test for three different measurement systems. The shaker swept from a rest, up to 10 Hz, and back down to a rest over 60 seconds. Lancelle, C., N. Lord, H. Wang, D. Fratta, R. Nigbor, A. Chalari, R. Karaulanov, J. Baldwin, and E. Castongia (2014), Directivity and Sensitivity of Fiber-Optic Cable Measuring Ground Motion using a Distributed Acoustic Sensing Array (abstract # NS31C-3935), AGU Fall Meeting. 
https://agu.confex.com/agu/fm1/meetingapp.cgi#Paper/19828 The e-poster is available at: https://agu.confex.com/data/handout/agu/fm14/Paper_19828_handout_696_0.pdf

  18. Flow-excited acoustic resonance of a Helmholtz resonator: Discrete vortex model compared to experiments

    SciTech Connect

    Dai, Xiwen; Jing, Xiaodong Sun, Xiaofeng

    2015-05-15

    The acoustic resonance in a Helmholtz resonator excited by a low Mach number grazing flow is studied theoretically. The nonlinear numerical model is established by coupling the vortical motion at the cavity opening with the cavity acoustic mode through an explicit force balancing relation between the two sides of the opening. The vortical motion is modeled in the potential flow framework, in which the oscillating motion of the thin shear layer is described by an array of convected point vortices, and the unsteady vortex shedding is determined by the Kutta condition. The cavity acoustic mode is obtained from the one-dimensional acoustic propagation model, the time-domain equivalent of which is given by means of a broadband time-domain impedance model. The acoustic resistances due to radiation and viscous loss at the opening are also taken into account. The physical processes of the self-excited oscillations, at both resonance and off-resonance states, are simulated directly in the time domain. Results show that the shear layer exhibits a weak flapping motion at the off-resonance state, whereas it rolls up into large-scale vortex cores when resonances occur. Single and dual-vortex patterns are observed corresponding to the first and second hydrodynamic modes. The simulation also reveals different trajectories of the two vortices across the opening when the first and second hydrodynamic modes co-exist. The strong modulation of the shed vorticity by the acoustic feedback at the resonance state is demonstrated. The model overestimates the pressure pulsation amplitude by a factor 2, which is expected to be due to the turbulence of the flow which is not taken into account. The model neglects vortex shedding at the downstream and side edges of the cavity. This will also result in an overestimation of the pulsation amplitude.

  19. Flow-excited acoustic resonance of a Helmholtz resonator: Discrete vortex model compared to experiments

    NASA Astrophysics Data System (ADS)

    Dai, Xiwen; Jing, Xiaodong; Sun, Xiaofeng

    2015-05-01

    The acoustic resonance in a Helmholtz resonator excited by a low Mach number grazing flow is studied theoretically. The nonlinear numerical model is established by coupling the vortical motion at the cavity opening with the cavity acoustic mode through an explicit force balancing relation between the two sides of the opening. The vortical motion is modeled in the potential flow framework, in which the oscillating motion of the thin shear layer is described by an array of convected point vortices, and the unsteady vortex shedding is determined by the Kutta condition. The cavity acoustic mode is obtained from the one-dimensional acoustic propagation model, the time-domain equivalent of which is given by means of a broadband time-domain impedance model. The acoustic resistances due to radiation and viscous loss at the opening are also taken into account. The physical processes of the self-excited oscillations, at both resonance and off-resonance states, are simulated directly in the time domain. Results show that the shear layer exhibits a weak flapping motion at the off-resonance state, whereas it rolls up into large-scale vortex cores when resonances occur. Single and dual-vortex patterns are observed corresponding to the first and second hydrodynamic modes. The simulation also reveals different trajectories of the two vortices across the opening when the first and second hydrodynamic modes co-exist. The strong modulation of the shed vorticity by the acoustic feedback at the resonance state is demonstrated. The model overestimates the pressure pulsation amplitude by a factor 2, which is expected to be due to the turbulence of the flow which is not taken into account. The model neglects vortex shedding at the downstream and side edges of the cavity. This will also result in an overestimation of the pulsation amplitude.

  20. Experiment Observation on Acoustic Forward Scattering for Underwater Moving Object Detection

    NASA Astrophysics Data System (ADS)

    Lei, Bo; Ma, Yuan-Liang; Yang, Kun-De

    2011-03-01

    The problem of detecting an object in shallow water by observing changes in the acoustic field as the object passes between an acoustic source and receiver is addressed. A signal processing scheme based on forward scattering is proposed to detect the perturbed field in the presence of the moving object. The periodic LFM wideband signal is transmitted and a sudden change of field is acquired using a normalized median filter. The experimental results on the lake show that the proposed scheme is successful for the detection of a slowly moving object in the bistatic blind zone.

  1. Extremely Low Loss Phonon-Trapping Cryogenic Acoustic Cavities for Future Physical Experiments

    PubMed Central

    Galliou, Serge; Goryachev, Maxim; Bourquin, Roger; Abbé, Philippe; Aubry, Jean Pierre; Tobar, Michael E.

    2013-01-01

    Low loss Bulk Acoustic Wave devices are considered from the point of view of the solid state approach as phonon-confining cavities. We demonstrate effective design of such acoustic cavities with phonon-trapping techniques exhibiting extremely high quality factors for trapped longitudinally-polarized phonons of various wavelengths. Quality factors of observed modes exceed 1 billion, with a maximum Q-factor of 8 billion and Q × f product of 1.6 · 1018 at liquid helium temperatures. Such high sensitivities allow analysis of intrinsic material losses in resonant phonon systems. Various mechanisms of phonon losses are discussed and estimated. PMID:23823569

  2. An impulsive source with variable output and stable bandwidth for underwater acoustic experiments.

    PubMed

    McNeese, Andrew R; Wilson, Preston S; Sagers, Jason D; Knobles, David P

    2014-07-01

    The Combustive Sound Source (CSS) is being developed as an environmentally friendly source to be used in ocean acoustics research and surveys. It has the ability to maintain the same wide bandwidth signal over a 20 dB drop in source level. The CSS consists of a submersible combustion chamber filled with a fuel/oxidizer mixture. The mixture is ignited and the ensuing combustion and bubble activity radiates an impulsive, thus broadband, acoustic pulse. The ability to control pulse amplitude while maintaining bandwidth is demonstrated. PMID:24993239

  3. Comparison of Computational Aeroacoustics Prediction of Acoustic Transmission Through a 3D Stator With Experiment

    NASA Technical Reports Server (NTRS)

    Hixon, Ray; Envia, Edmane; Dahl, Milo; Sutliff, Daniel L.

    2014-01-01

    In this paper, numerical predictions of acoustic transmission through a 3D stator obtained using the NASA BASS code are compared with experimentally measured data. The influence of vane count and stagger as well as frequency and mode order on the transmission loss is investigated. The data-theory comparisons indicate that BASS can predict all the important trends observed in the experimental data.

  4. Comparison of Computational Aeroacoustics Prediction of Acoustic Transmission Through a 3D Stator with Experiment

    NASA Technical Reports Server (NTRS)

    Hixon, Ray; Envia, Edmane; Dahl, Milo; Sutliff, Daniel

    2014-01-01

    In this paper, numerical predictions of acoustic transmission through a 3D stator obtained using the NASA BASS code are compared with experimentally measured data. The influence of vane count and stagger as well as frequency and mode order on the transmission loss is investigated. The data-theory comparisons indicate that BASS can predict all the important trends observed in the experimental data.

  5. Technically Speaking: On the Structure and Experience of Interaction Involving Augmentative Alternative Communications

    ERIC Educational Resources Information Center

    Engelke, Christopher Robert

    2013-01-01

    Technically Speaking: On the Structure and Experience of Interaction Involving Augmentative Alternative Communications examines the ways that communication is structured and experienced by looking at interactions involving augmented communicators--people with severe speech disabilities who use forms of assistive technology in order to communicate…

  6. Localization of short-range acoustic and seismic wideband sources: Algorithms and experiments

    NASA Astrophysics Data System (ADS)

    Stafsudd, J. Z.; Asgari, S.; Hudson, R.; Yao, K.; Taciroglu, E.

    2008-04-01

    We consider the determination of the location (source localization) of a disturbance source which emits acoustic and/or seismic signals. We devise an enhanced approximate maximum-likelihood (AML) algorithm to process data collected at acoustic sensors (microphones) belonging to an array of, non-collocated but otherwise identical, sensors. The approximate maximum-likelihood algorithm exploits the time-delay-of-arrival of acoustic signals at different sensors, and yields the source location. For processing the seismic signals, we investigate two distinct algorithms, both of which process data collected at a single measurement station comprising a triaxial accelerometer, to determine direction-of-arrival. The direction-of-arrivals determined at each sensor station are then combined using a weighted least-squares approach for source localization. The first of the direction-of-arrival estimation algorithms is based on the spectral decomposition of the covariance matrix, while the second is based on surface wave analysis. Both of the seismic source localization algorithms have their roots in seismology; and covariance matrix analysis had been successfully employed in applications where the source and the sensors (array) are typically separated by planetary distances (i.e., hundreds to thousands of kilometers). Here, we focus on very-short distances (e.g., less than one hundred meters) instead, with an outlook to applications in multi-modal surveillance, including target detection, tracking, and zone intrusion. We demonstrate the utility of the aforementioned algorithms through a series of open-field tests wherein we successfully localize wideband acoustic and/or seismic sources. We also investigate a basic strategy for fusion of results yielded by acoustic and seismic arrays.

  7. Computationally efficient parabolic equation solutions to seismo-acoustic problems involving thin or low-shear elastic layers.

    PubMed

    Metzler, Adam M; Collis, Jon M

    2013-04-01

    Shallow-water environments typically include sediments containing thin or low-shear layers. Numerical treatments of these types of layers require finer depth grid spacing than is needed elsewhere in the domain. Thin layers require finer grids to fully sample effects due to elasticity within the layer. As shear wave speeds approach zero, the governing system becomes singular and fine-grid spacing becomes necessary to obtain converged solutions. In this paper, a seismo-acoustic parabolic equation solution is derived utilizing modified difference formulas using Galerkin's method to allow for variable-grid spacing in depth. Propagation results are shown for environments containing thin layers and low-shear layers. PMID:23556690

  8. Subjective evaluation of speech and noise in learning environments in the realm of classroom acoustics: Results from laboratory and field experiments

    NASA Astrophysics Data System (ADS)

    Meis, Markus; Nocke, Christian; Hofmann, Simone; Becker, Bernhard

    2005-04-01

    The impact of different acoustical conditions in learning environments on noise annoyance and the evaluation of speech quality were tested in a series of three experiments. In Experiment 1 (n=79) the auralization of seven classrooms with reverberation times from 0.55 to 3.21 s [average between 250 Hz to 2 kHz] served to develop a Semantic Differential, evaluating a simulated teacher's voice. Four factors were found: acoustical comfort, roughness, sharpness, and loudness. In Experiment 2, the effects of two classroom renovations were examined from a holistic perspective. The rooms were treated acoustically with acoustic ceilings (RT=0.5 s [250 Hz-2 kHz]) and muffling floor materials as well as non-acoustically with a new lighting system and color design. The results indicate that pupils (n=61) in renovated classrooms judged the simulated voice more positively, were less annoyed from the noise in classrooms, and were more motivated to participate in the lessons. In Experiment 3 the sound environments from six different lecture rooms (RT=0.8 to 1.39 s [250 Hz-2 kHz]) in two Universities of Oldenburg were evaluated by 321 students during the lectures. Evidence found supports the assumption that acoustical comfort in rooms is dependent on frequency for rooms with higher reverberation times.

  9. Community College Transfer Student Involvement Experiences at a Selective, Private Four-Year University

    ERIC Educational Resources Information Center

    Castillo, Carolina

    2011-01-01

    This dissertation tested the constructs of academic and social involvement and adjustment on grades as a pathway to explain community college transfer student experiences beyond the concept of transfer shock. The study contributes to the growing body of literature on Latina(o) community college transfer student experiences with the application of…

  10. An Inorganic Laboratory Experiment Involving Photochemistry, Liquid Chromatography, and Infrared Spectroscopy.

    ERIC Educational Resources Information Center

    Post, Elroy W.

    1980-01-01

    Presents an experiment involving photochemical legand displacement on a metal carbonyl, separation of the product mixture by chromotography, and identification of the components by use of infrared spectroscopy and group theory. The chromatography and spectroscopy are combined as complementary tools in this experiment. (Author/JN)

  11. Educational Support System for Experiments Involving Construction of Sound Processing Circuits

    ERIC Educational Resources Information Center

    Takemura, Atsushi

    2012-01-01

    This paper proposes a novel educational support system for technical experiments involving the production of practical electronic circuits for sound processing. To support circuit design and production, each student uses a computer during the experiments, and can learn circuit design, virtual circuit making, and real circuit making. In the…

  12. The Northern Experience of Street-Involved Youth: A Narrative Inquiry

    ERIC Educational Resources Information Center

    George, Serena D.; O'Neill, Linda K.

    2011-01-01

    This research explored the experiences of 8 street-involved youth (4 male, 4 female) between the ages of 20 and 27 living in north-central British Columbia. The analysis was carried out in 3 phases based on the narrative approach developed by Lieblich, Tuval-Mashiach, and Zilber (1998). The narratives represented the holistic experiences of the…

  13. Scanning electron acoustic microscopy of residual stresses in ceramics: Theory and experiment

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Qian, Menglu

    1992-01-01

    Several reviews have highlighted a number of applications of scanning electron acoustic microscopy (SEAM) to metals and semiconductors which show that SEAM can provide new information on surface and near-surface features of such materials, but there have been few studies attempting to determine the capabilities of SEAM for characterizing ceramic materials. We have recently observed image contrast in SEAM from residual stress fields induced in brittle materials by Vickers indentations that is strongly dependent on the electron beam chopping frequency. We have also recently developed a three-dimensional mathematical model of signal generation and contrast in SEAM, appropriate to the brittle materials studied, that we use as a starting point in this paper for modeling the effect of residual stress fields on the generated electron acoustic signal. The influence of the electron beam chopping frequency is also considered under restrictive assumptions.

  14. Analysis of an existing experiment on the interaction of acoustic waves with a laminar boundary layer

    NASA Technical Reports Server (NTRS)

    Schopper, M. R.

    1982-01-01

    The hot-wire anemometer amplitude data contained in the 1977 report of P. J. Shapiro entitled, ""The Influence of Sound Upon Laminar Boundary'' were reevaluated. Because the low-Reynolds number boundary layer disturbance data were misinterpreted, an effort was made to improve the corresponding disturbance growth rate curves. The data are modeled as the sum of upstream and downstream propagating acoustic waves and a wave representing the Tollmien-Schlichting (TS) wave. The amplitude and phase velocity of the latter wave were then adjusted so that the total signal reasonably matched the amplitude and phase angle hot-wire data along the plate laminar boundary layer. The revised rates show growth occurring further upstream than Shapiro found. It appears that the premature growth is due to the adverse pressure gradient created by the shape of the plate. Basic elements of sound propagation in ducts and the experimental and theoretical acoustic-stability literature are reviewed.

  15. Ocean seismo-acoustics. Low-frequency underwater acoustics

    SciTech Connect

    Akal, T.; berkson, J.M.

    1986-01-01

    This book presents information on seismo-acoustic propagation in seawater and sea beds that includes theoretical developments, modelling and experiments, and fluctuations. Boundary scatteiring, seismo-acoustic waves and seismo-acoustic noise are discussed. Technology and new approaches in seismo-acoustic measurements are presented.

  16. Sound propagation in and radiation from acoustically lined flow ducts: A comparison of experiment and theory

    NASA Technical Reports Server (NTRS)

    Plumblee, H. E., Jr.; Dean, P. D.; Wynne, G. A.; Burrin, R. H.

    1973-01-01

    The results of an experimental and theoretical study of many of the fundamental details of sound propagation in hard wall and soft wall annular flow ducts are reported. The theory of sound propagation along such ducts and the theory for determining the complex radiation impedance of higher order modes of an annulus are outlined, and methods for generating acoustic duct modes are developed. The results of a detailed measurement program on propagation in rigid wall annular ducts with and without airflow through the duct are presented. Techniques are described for measuring cut-on frequencies, modal phase speed, and radial and annular mode shapes. The effects of flow velocity on cut-on frequencies and phase speed are measured. Comparisons are made with theoretical predictions for all of the effects studies. The two microphone method of impedance is used to measure the effects of flow on acoustic liners. A numerical study of sound propagation in annular ducts with one or both walls acoustically lined is presented.

  17. Perception of Male Caller Identity in Koalas (Phascolarctos cinereus): Acoustic Analysis and Playback Experiments

    PubMed Central

    Charlton, Benjamin D.; Ellis, William A. H.; McKinnon, Allan J.; Brumm, Jacqui; Nilsson, Karen; Fitch, W. Tecumseh

    2011-01-01

    The ability to signal individual identity using vocal signals and distinguish between conspecifics based on vocal cues is important in several mammal species. Furthermore, it can be important for receivers to differentiate between callers in reproductive contexts. In this study, we used acoustic analyses to determine whether male koala bellows are individually distinctive and to investigate the relative importance of different acoustic features for coding individuality. We then used a habituation-discrimination paradigm to investigate whether koalas discriminate between the bellow vocalisations of different male callers. Our results show that male koala bellows are highly individualized, and indicate that cues related to vocal tract filtering contribute the most to vocal identity. In addition, we found that male and female koalas habituated to the bellows of a specific male showed a significant dishabituation when they were presented with bellows from a novel male. The significant reduction in behavioural response to a final rehabituation playback shows this was not a chance rebound in response levels. Our findings indicate that male koala bellows are highly individually distinctive and that the identity of male callers is functionally relevant to male and female koalas during the breeding season. We go on to discuss the biological relevance of signalling identity in this species' sexual communication and the potential practical implications of our findings for acoustic monitoring of male population levels. PMID:21633499

  18. 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.

  19. The Physical Context of the Southern Ocean Iron Experiment as Observed by Shipboard Acoustic Doppler Current Profilers

    NASA Astrophysics Data System (ADS)

    Brewster, J.; Pierce, S. D.

    2002-12-01

    The Southern Ocean Iron Experiment in January-February 2002 involved three ships making numerous measurements to help quantify and study two iron-infused patches of water. The main purpose of the study was to investigate the biological and chemical effects of iron fertilization on phytoplankton productivity. Physical processes in the Southern Ocean play a large role in the formation, evolution, and eventual dispersion of natural phytoplankton patches. The Northern (56 S) and Southern (66.5 S) patches were infused with iron sulfate three and four times, respectively, and tracked over a seven week period. Two of the ships, the R/V Revelle and the R/V Melville, were outfitted with 150 kHz narrowband acoustic Doppler current profilers. Good quality velocity data between 20 and 300 m depths are available continuously along the shiptracks. The available transects running south in the vicinity of 170 W, from 52-66.5 S, reveal the zonally banded velocity structure characteristic of the Antarctic Circumpolar Current. To the north of the 59-61 S Polar Frontal zone, mesoscale bands of eastward currents up to 0.4 m/s alternate with generally smaller westward bands. Farther south, the alternating structure continues but with smaller eastward velocities of about 0.2 m/s. The Northern iron patch was successfully created in a relatively low-velocity region amidst strong velocities immediately north and south. The overall mean velocity during the initial Northern patch occupation by the R/V Revelle (12-19 January) was small and northward at 0.1 m/s. By the second Revelle occupation of the Northern patch (8-10 February), however, the mean patch velocity was 0.2 m/s to the east-northeast. Significantly, the patch at this time extended across the flank of a strong eastward jet, associated with a sharp surface temperature change from 8-11 C. Whereas the northern end of the North patch experienced a strong 0.5 m/s northeast velocity, the southern end remained in a low-velocity region

  20. Acoustic data analysis and scenario over watch from an aerostat at the NATO SET-153 field experiment

    NASA Astrophysics Data System (ADS)

    Reiff, Christian; Scanlon, Michael

    2012-06-01

    The purpose of the NATO SET-153 field experiment was to provide an opportunity to demonstrate multiple sensor technologies in an urban environment and determine integration capabilities for future development. The Army Research Laboratory (ARL) experimental aerostat was used primarily as a persistent over watch capability as a substitute for a UAV. Continuous video was recorded on the aerostat and segments of video were captured of the scenarios on the ground that the camera was following manually. Some of the segments showing scenario activities will be presented. The captured pictures and video frames have telemetry in the headers that provides the UTM time and the Inertial Navigation System (INS) GPS location and the inertial roll, pitch, and yaw as well as the camera gimbal pan and tilt angles. The timing is useful to synchronize the images with the scenario events providing activity ground truth. The INS, GPS, and camera gimbal angle values can be used with the acoustic solution for the location of a sound source to determine the relative accuracy of the solution if the camera is pointed at the sound source. This method will be confirmed by the use of a propane cannon whose GPS location is logged. During the field experiment, other interesting acoustic events such as vehicle convoys, platoon level firefights with vehicles using blanks, and a UAV helicopter were recorded and will be presented in a quick analysis.

  1. Heterodyne signal-to-noise ratios in acoustic mode scattering experiments

    NASA Technical Reports Server (NTRS)

    Cochran, W. R.

    1980-01-01

    The relation between the signal to noise ratio (SNR) obtained in heterodyne detection of radiation scattered from acoustic modes in crystalline solids and the scattered spectral density function is studied. It is shown that in addition to the information provided by the measured frequency shifts and line widths, measurement of the SNR provides a determination of the absolute elasto-optical (Pockel's) constants. Examples are given for cubic crystals, and acceptable SNR values are obtained for scattering from thermally excited phonons at 10.6 microns, with no external perturbation of the sample necessary. The results indicate the special advantages of the method for the study of semiconductors.

  2. Parents' Experiences as Predictors of State Accountability Measures of Schools' Facilitation of Parent Involvement

    ERIC Educational Resources Information Center

    Elbaum, Batya; Blatz, Erin T.; Rodriguez, Raymond J.

    2016-01-01

    The aim of this study was to ascertain which dimensions of parents' experiences with schools are most strongly associated with parents' perceptions that schools are or are not facilitating parent involvement as mandated by the federal accountability system under the Individuals With Disabilities Education Act (IDEA). Participants were 92 parents…

  3. Parental Beliefs and Experiences Regarding Involvement in Intervention for Their Child with Speech Sound Disorder

    ERIC Educational Resources Information Center

    Watts Pappas, Nicole; McAllister, Lindy; McLeod, Sharynne

    2016-01-01

    Parental beliefs and experiences regarding involvement in speech intervention for their child with mild to moderate speech sound disorder (SSD) were explored using multiple, sequential interviews conducted during a course of treatment. Twenty-one interviews were conducted with seven parents of six children with SSD: (1) after their child's initial…

  4. Experiences of Artists and Artist-Teachers Involved in Teacher Professional Development Programs

    ERIC Educational Resources Information Center

    Upitis, Rena

    2005-01-01

    This research explores the experiences of artists and artist-teachers involved in two professional development programs for arts education: a national Canadian program and a state-wide American program. Both programs aim to help classroom teachers develop ways of teaching in and through the arts by interacting with partnering artists and/or arts…

  5. E-Learning System for Experiments Involving Construction of Practical Electronic Circuits

    ERIC Educational Resources Information Center

    Takemura, Atsushi

    2013-01-01

    This paper proposes a novel e-learning system for technical experiments involving the construction of practical electronic circuits; this system would meet the various demands of individual experimenters. This mixed mode is beneficial for practical use in that an experimenter who does not have sufficient circuit components for circuit making can…

  6. From Corrections to Community: The Juvenile Reentry Experience as Characterized by Multiple Systems Involvement

    ERIC Educational Resources Information Center

    Cusick, Gretchen Ruth; Goerge, Robert M.; Bell, Katie Claussen

    2009-01-01

    This Chapin Hall report describes findings on the extent of system involvement among Illinois youth released from correctional facilities, tracking a population of youth under age 18 in Illinois following their release. Using administrative records, researchers develop profiles of reentry experiences across the many systems that serve youth and…

  7. Collegiate Diversity Experiences and Students' Views Regarding Social and Political Involvement

    ERIC Educational Resources Information Center

    Parker, Eugene T., III; Trolian, Teniell L.

    2015-01-01

    Using data from the Wabash National Study of Liberal Arts Education, this study examines the relationship between engagement in diversity experiences during college and student attitudes about the importance of being socially and politically involved at the end of their fourth year of college. Findings suggest a positive link between…

  8. Improving Community Involvement and Citizenship among Elementary School Students through Service Learning Experiences

    ERIC Educational Resources Information Center

    Smith, Mandi

    2007-01-01

    This Action Research Project was designed to increase student awareness and involvement of socio-economic differences and how the children can make a difference in their community. Service learning projects were non-existent at the Academy causing the young children to miss out on learning experiences that would teach them how to make a difference…

  9. Binaural Simulation Experiments in the NASA Langley Structural Acoustics Loads and Transmission Facility

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.; Silcox, Richard (Technical Monitor)

    2001-01-01

    A location and positioning system was developed and implemented in the anechoic chamber of the Structural Acoustics Loads and Transmission (SALT) facility to accurately determine the coordinates of points in three-dimensional space. Transfer functions were measured between a shaker source at two different panel locations and the vibrational response distributed over the panel surface using a scanning laser vibrometer. The binaural simulation test matrix included test runs for several locations of the measuring microphones, various attitudes of the mannequin, two locations of the shaker excitation and three different shaker inputs including pulse, broadband random, and pseudo-random. Transfer functions, auto spectra, and coherence functions were acquired for the pseudo-random excitation. Time histories were acquired for the pulse and broadband random input to the shaker. The tests were repeated with a reflective surface installed. Binary data files were converted to universal format and archived on compact disk.

  10. Head and Neck Schwannomas: 20-Year Experience of a Single Institution Excluding Cutaneous and Acoustic Sites.

    PubMed

    Butler, Randall T; Patel, Rajiv M; McHugh, Jonathan B

    2016-09-01

    While head and neck sites comprise the most common location of schwannomas, clinicopathologic data regarding those tumors occurring in non-acoustic and non-cutaneous locations are relatively sparse. In this study, therefore, we sought to examine retrospectively the clinical and pathologic features of head and neck schwannomas excised at our institution over a 20-year period. During this period, we identified a total cohort of 85 patients, which included 36 males (42.4 %) and 49 females with average age of 41.3 years, the majority of which presented asymptomatically with a mass. Localized symptoms were, however, associated with all of the schwannomas that arose in the oral cavity and larynx, while tumors within or adjacent to bone were often associated with neurologic complaints (7 of 15 such tumors [46.7 %]). Clinical follow-up data was available in 86.4 % of all cases and demonstrated no recurrences or mortality. Pathologically, the microscopic features were characteristic of those well-described for schwannomas in other sites, including alternating Antoni A and B areas and the presence of degenerative changes. Tumor encapsulation, however, was variable and was completely absent in schwannomas of the nasal cavity, paranasal sinuses, and larynx. Additionally, a significant minority of the tumors (28.2 %) exhibited foci that resembled neurofibroma. Non-acoustic, non-cutaneous schwannomas of the head and neck appear to have clinicopathologic features similar to their soft tissue counterparts with some subsite variation in presentation and/or microscopic features. PMID:26747460

  11. REMORA 3: The first instrumented fuel experiment with on-line gas composition measurement by acoustic sensor

    SciTech Connect

    Lambert, T.; Muller, E.; Federici, E.; Rosenkrantz, E.; Ferrandis, J. Y.; Tiratay, X.; Silva, V.; Machard, D.; Trillon, G.

    2011-07-01

    With the aim to improve the knowledge of nuclear fuel behaviour, the development of advanced instrumentation used during in-pile experiments in Material Testing Reactor (MTR) is necessary. To obtain data on high Burn-Up MOX fuel performance under transient operating conditions, especially in order to differentiate between the kinetics of fission gas and helium releases and to acquire data on the degradation of the fuel conductivity, a highly instrumented in-pile experiment called REMORA 3 has been conducted by CEA and IES (Southern Electronic Inst. - CNRS - Montpellier 2 Univ.). A rodlet extracted from a fuel rod base irradiated for five cycles in a French EDF commercial PWR has been re-instrumented with a fuel centerline thermocouple, a pressure transducer and an advanced acoustic sensor. This latter, patented by CEA and IES, is 1 used in addition to pressure measurement to determine the composition of the gases located in the free volume and the molar fractions of fission gas and helium. This instrumented fuel rodlet has been re-irradiated in a specific rig, GRIFFONOS, located in the periphery of the OSIRIS experimental reactor core at CEA Saclay. First of all, an important design stage and test phases have been performed before the irradiation in order to optimize the response and the accuracy of the sensors: - To control the influence of the temperature on the acoustic sensor behaviour, a thermal mock-up has been built. - To determine the temperature of the gas located in the acoustic cavity as a function of the coolant temperature, and the average temperature of the gases located in the rodlet free volume as a function of the linear heat rate, thermal calculations have been achieved. The former temperature is necessary to calculate the molar fractions of the gases and the latter is used to calculate the total amount of released gas from the internal rod pressure measurements. - At the end of the instrumented rod manufacturing, specific internal free volume and

  12. Testicular microlithiasis and preliminary experience of acoustic radiation force impulse imaging

    PubMed Central

    Osther, Palle Jørn Sloth; Rafaelsen, Søren Rafael

    2016-01-01

    Background Elastography of the testis can be used as a part of multiparametric examination of the scrotum. Purpose To determine the testicular stiffness using acoustic radiation force impulse imaging (ARFI) technique in men with testicular microlithiasis (TML). Material and Methods In 2013, 12 patients with diagnosed testicular microlithiasis in 2008 (mean age, 51 years; age range, 25–76 years) underwent a 5-year follow-up B-mode ultrasonography with three ARFI elastography measurements of each testis. We used a Siemens Acuson S3000 machine. Results No malignancy was found at the 5-year follow-up B-mode and elastography in 2013. However, we found an increase in TML; in the previous ultrasonography in 2008, eight men had bilateral TML, whereas in 2013, 10 men were diagnosed with bilateral TML. The mean elasticity of testicles with TML was 0.82 m/s (interquartile range [IQR], 0.72–0.88 m/s; range, 65–1.08 m/s). Conclusion Elastography velocity of testis with TML seems to be in the same velocity range as in men with normal testis tissue. PMID:27504193

  13. Heterogeneous freezing of single sulphuric acid solution droplets: laboratory experiments utilising an acoustic levitator

    NASA Astrophysics Data System (ADS)

    Ettner, M.; Mitra, S. K.; Borrmann, S.

    2004-03-01

    The heterogeneous freezing temperatures of single binary sulphuric acid solution droplets were measured in dependency of acid concentration down to temperatures as low as -70°C. In order to avoid influence of supporting substrates on the freezing characteristics, the droplets were suspended by means of an acoustic levitator. The droplets contained immersed particles of graphite, kaolin or montmorillonite in order to study the influence of the presence of such contamination on the freezing temperature. The radii of the suspended droplets spanned the range between 0,4 and 1,1 mm and the concentration of the sulphuric acid solution varied between 5 and 25 weight percent. The presence of the particles in the solution raises the freezing temperature with respect to homogeneous freezing of these solution droplets. The pure solution droplets can be supercooled up to 40° below the ice-acid solution thermodynamic equilibrium curve. Depending on the concentration of sulphuric acid and the nature of the impurity the polluted droplets froze between -11°C and -35°C. The experimental set-up, combining a deep freezer with a movable ultrasonic levitator and suitable optics, proved to be a useful approach for such investigations on individual droplets.

  14. Heterogeneous freezing of single sulfuric acid solution droplets: laboratory experiments utilizing an acoustic levitator

    NASA Astrophysics Data System (ADS)

    Ettner, M.; Mitra, S. K.; Borrmann, S.

    2004-09-01

    The heterogeneous freezing temperatures of single binary sulfuric acid solution droplets were measured in dependency of acid concentration down to temperatures as low as -50°C. In order to avoid influence of supporting substrates on the freezing characteristics, a new technique has been developed to suspend the droplet by means of an acoustic levitator. The droplets contained immersed particles of graphite, kaolin or montmorillonite in order to study the influence of the presence of such contamination on the freezing temperature. The radii of the suspended droplets spanned the range between 0.4 and 1.1mm and the concentration of the sulfuric acid solution varied between 5 and 14 weight percent. The presence of the particles in the solution raises the freezing temperature with respect to homogeneous freezing of these solution droplets. The pure solution droplets can be supercooled up to 40 degrees below the ice-acid solution thermodynamic equilibrium curve. Depending on the concentration of sulfuric acid and the nature of the impurity the polluted droplets froze between -11°C and -35°C. The new experimental set-up, combining a deep freezer with a movable ultrasonic levitator and suitable optics, proved to be a useful approach for such investigations on individual droplets.

  15. Visual and Acoustic Confusability of Target Letters and the Word Superiority Effect.

    ERIC Educational Resources Information Center

    Chastain, Garvin; And Others

    The hypothesis that word context reduces visual rather than acoustic confusion between possible targets was tested in a series of experiments. All involved tachistoscopic presentation of letter strings followed by a pattern mask. Data from eight college students showed that target letters that are confusable only visually and acoustically ("b" and…

  16. Feasibility of reduced gravity experiments involving quiescent, uniform particle cloud combustion

    NASA Technical Reports Server (NTRS)

    Ross, Howard D.; Facca, Lily T.; Berlad, Abraham L.; Tangirala, Venkat

    1989-01-01

    The study of combustible particle clouds is of fundamental scientific interest as well as a practical concern. The principal scientific interests are the characteristic combustion properties, especially flame structure, propagation rates, stability limits, and the effects of stoichiometry, particle type, transport phenomena, and nonadiabatic processes on these properties. The feasibility tests for the particle cloud combustion experiment (PCCE) were performed in reduced gravity in the following stages: (1) fuel particles were mixed into cloud form inside a flammability tube; (2) when the concentration of particles in the cloud was sufficiently uniform, the particle motion was allowed to decay toward quiescence; (3) an igniter was energized which both opened one end of the tube and ignited the suspended particle cloud; and (4) the flame proceeded down the tube length, with its position and characteristic features being photographed by high-speed cameras. Gravitational settling and buoyancy effects were minimized because of the reduced gravity enviroment in the NASA Lewis drop towers and aircraft. Feasibility was shown as quasi-steady flame propagation which was observed for fuel-rich mixtures. Of greatest scientific interest is the finding that for near-stoichiometric mixtures, a new mode of flame propagation was observed, now called a chattering flame. These flames did not propagate steadily through the tube. Chattering modes of flame propagation are not expected to display extinction limits that are the same as those for acoustically undisturbed, uniform, quiescent clouds. A low concentration of fuel particles, uniformly distributed in a volume, may not be flammable but may be made flammable, as was observed, through induced segregation processes. A theory was developed which showed that chattering flame propagation was controlled by radiation from combustion products which heated the successive discrete laminae sufficiently to cause autoignition.

  17. Proving experiments on an acoustic transmission suite and its reverberation room

    NASA Astrophysics Data System (ADS)

    Plumb, G. D.

    An Acoustic Transmission Suite is a facility used for the laboratory measurement of the airborne sound transmission properties of partitions. It consists of a pair of adjoining rooms, the source room and the receive room, with a hole for the construction of the test partition in their common walls. The building is designed to minimize the sound power flow by paths other than that through the test partition. Such a facility has recently been built at the British Broadcasting Corporation (BBC) Research Department. A double brick cavity wall was built to allow the limiting sound insulation performance between the source and receive rooms in the Transmission Suite to be measured. This performance is effectively equal to that which would be measured with a perfectly isolating partition in place, and limits the maximum insulation that could be measured using the Suite. The actual isolation was shown to be impaired by a rigid bond between the test wall and the receive room walls. A demountable lightweight partition was fitted firstly to the receive and then to the source room side of the test wall. This improved the isolation of the test wall and proved that the rigid bond at its edges had been the cause of the impaired isolation. It also revealed a void above the test wall, and a further weakness through the cavity between the source and receive rooms. The mean limiting sound reduction index between the source and receive rooms was shown to be 65 dB, provided that the cavity between source and receive rooms was sealed. In future, a mechanism must be employed which provides vibration isolation between the test wall and the Transmission Suite building structure. The receive room was designed to meet the specifications detailed in the ISO-Standard for reverberation rooms. Proving tests were carried out on the reverberation room and repeatability tests were carried out to evaluate the minimum number of decays needed in each frequency band for absorption coefficient

  18. Packages of participation: Swedish employees’ experience of Lean depends on how they are involved

    PubMed Central

    Brännmark, Mikael; Holden, Richard J.

    2013-01-01

    Background Lean Production is a dominant approach in Swedish and global manufacturing and service industries. Studies of Lean’s employee effects are few and contradictory. Purpose Employee effects from Lean are likely not uniform. This paper investigates the effect of employees' participation on their experiences of Lean. Method This study investigated how different packages of employee participation in Lean affected manufacturing workers’ experiences of Lean. During 2008–2011, qualitative and quantitative data were collected from Swedish manufacturing companies participating in the national Swedish Lean Production program Produktionslyftet. Data from 129 surveys (28 companies), 39 semi-structured interviews, and 30 reports were analyzed. In the main analysis, comparisons were made of the survey-reported Lean experiences of employees in three groups: temporary group employees (N = 36), who participated in Lean mostly through intermittent projects; continuous group employees (N = 69), who participated through standing improvement groups; and combined group employees (N = 24), who participated in both ways. Results Continuous group employees had the most positive experience of Lean, followed by the combined group. Temporary group employees had the least positive experiences, being less likely than their counterparts to report that Lean improved teamwork, occupational safety, and change-related learning, decision making, and authority. Conclusions These findings support the importance of continuous, structured opportunities for participation but raise the possibility that more participation may result in greater workload and role overload, mitigating some benefits of employee involvement. Consequently, companies should consider involving employees in change efforts but should attend to the specific design of participation activities. PMID:24665370

  19. 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.

  20. A note on acoustic measurements of turbulence, suspended sediment, and bed forms in mobile bed experiments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One of the challenges of hydraulic experimentation is designing experiments that are complex enough to capture relevant processes while retaining the simplicity necessary for useful, accurate measurements. The intricacy of the interactions between turbulent flows and mobile beds in rivers and stream...

  1. Classical Experiments Revisited: Smartphones and Tablet PCs as Experimental Tools in Acoustics and Optics

    ERIC Educational Resources Information Center

    Klein, P.; Hirth, M.; Gröber, S.; Kuhn, J.; Müller, A.

    2014-01-01

    Smartphones and tablets are used as experimental tools and for quantitative measurements in two traditional laboratory experiments for undergraduate physics courses. The Doppler effect is analyzed and the speed of sound is determined with an accuracy of about 5% using ultrasonic frequency and two smartphones, which serve as rotating sound emitter…

  2. A phenomenographic analysis of first-year engineering students' experiences with problems involving multiple possible solutions

    NASA Astrophysics Data System (ADS)

    Dringenberg, Emily A.

    Engineers are expected to solve problems that are ill-structured. These problems are presented with a lack of necessary information and allow for different ways of engaging with the problem; they are open-ended and involve multiple possible solutions with multiple means of evaluation. In order to allow maximum time for students to develop skills for solving such problems, undergraduate engineering programs can introduce such problems during the first year of students' education, in the form of cornerstone design tasks. This provides students with more opportunities to develop their ability to engage with ill-structured problems, which are characteristic of engineering work. Researchers have documented variation within both the behavior and perceptions of students' early experiences with design problems. General themes include novice-like design behavior, discomfort with lack of information, difficulty with problem scoping, and resistance to ambiguity. To build on these generalizations of students' experiences, a more thorough understanding of the variation in how students experience this phenomenon of engaging with ill-structured problems is needed to design effective learning environments. This work presents the qualitatively different ways that engineering students experience problems with multiple possible solutions during their first year of engineering studies. Using phenomenography as the methodological framework, data were collected through in-depth, semi-structured interviews with 27 first-year engineering students. The iterative, phenomenographic analysis resulted in seven descriptive categories for the ways participants experienced problems involving multiple possible solutions. The names of these categories represent the different foci of the students' experiences: completion, transition, iteration, organization, collaboration, reasoning, and growth. These categories are organized along two crucial dimensions of variation: reaction to ambiguity and role

  3. Classical experiments revisited: smartphones and tablet PCs as experimental tools in acoustics and optics

    NASA Astrophysics Data System (ADS)

    Klein, P.; Hirth, M.; Gröber, S.; Kuhn, J.; Müller, A.

    2014-07-01

    Smartphones and tablets are used as experimental tools and for quantitative measurements in two traditional laboratory experiments for undergraduate physics courses. The Doppler effect is analyzed and the speed of sound is determined with an accuracy of about 5% using ultrasonic frequency and two smartphones, which serve as rotating sound emitter and stationary sound detector. Emphasis is put on the investigation of measurement errors in order to judge experimentally derived results and to sensitize undergraduate students to the methods of error estimates. The distance dependence of the illuminance of a light bulb is investigated using an ambient light sensor of a mobile device. Satisfactory results indicate that the spectrum of possible smartphone experiments goes well beyond those already published for mechanics.

  4. Sexual risk, substance use, mental health, and trauma experiences of gang-involved homeless youth.

    PubMed

    Petering, Robin

    2016-04-01

    This study examined the associations of sexual risk behaviors, substance use, mental health, and trauma with varying levels of gang involvement in a sample of Los Angeles-based homeless youths. Data were collected from 505 homeless youths who self-reported various health information and whether they have ever identified as or been closely affiliated with a gang member. Multivariable logistic regression assessed associations of lifetime gang involvement with risk taking behaviors and negative health outcomes. Results revealed seventeen percent of youths have ever identified as a gang member and 46% as gang affiliated. Both gang members and affiliates were at greater risk of many negative behaviors than non-gang involved youths. Gang members and affiliates were more likely to report recent methamphetamine use, cocaine use, chronic marijuana use, having sex while intoxicated, and symptoms of depression, symptoms of posttraumatic stress disorder. They were also more likely to have experienced childhood sexual abuse and witnessing family violence. Gang members were more likely to ever attempt suicide, experience recent partner violence, and report physical abuse during childhood. Results suggest that lifetime gang involvement is related to a trajectory of negative outcomes and amplified risk for youths experiencing homelessness. Additionally, being closely connected to a gang member appears to have just as much as an impact on risk as personally identifying as a gang member. Given the lack of knowledge regarding the intersection between youth homelessness and gang involvement, future research is needed to inform policies and programs that can address the specific needs of this population. PMID:26897432

  5. Beta-induced Alfven-acoustic eigenmodes in National Spherical Torus Experiment and DIII-D driven by beam ions

    SciTech Connect

    Gorelenkov, N. N.; Darrow, D.; Fredrickson, E.; Fu, G.-Y.; Menard, J.; Nazikian, R.; Van Zeeland, M. A.; Berk, H. L.; Crocker, N. A.; Heidbrink, W. W.

    2009-05-15

    Kinetic theory and experimental observations of a special class of energetic particle driven instabilities called here beta-induced Alfven-acoustic eigenmodes (BAAEs) are reported confirming, previous results [N. N. Gorelenkov et al., Plasma Phys. Controlled Fusion 49, B371 (2007)]. The kinetic theory is based on the ballooning dispersion relation where the drift frequency effects are retained. BAAE gaps are recovered in kinetic theory. It is shown that the observed certain low-frequency instabilities on DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] and National Spherical Torus Experiment [M. Ono, S. M. Kaye, Y.-K. M. Peng et al., Nucl. Fusion 40, 557 (2000)] are consistent with their identification as BAAEs. BAAEs deteriorate the fast ion confinement in DIII-D and can have a similar effect in next-step fusion plasmas, especially if excited together with multiple global toroidicity-induced shear Alfven eigenmode instabilities. BAAEs can also be used to diagnose safety factor profiles, a technique known as magnetohydrodynamic spectroscopy.

  6. Experiments on nonlinear acoustic landmine detection: Tuning curve studies of soil-mine and soil-mass oscillators

    NASA Astrophysics Data System (ADS)

    Korman, Murray S.; Witten, Thomas R.; Fenneman, Douglas J.

    2004-10-01

    Donskoy [SPIE Proc. 3392, 211-217 (1998); 3710, 239-246 (1999)] has suggested a nonlinear technique that is insensitive to relatively noncompliant targets that can detect an acoustically compliant buried mine. Airborne sound at two primary frequencies eventually causes interactions with the soil and mine generating combination frequencies that can affect the vibration velocity at the surface. In current experiments, f1 and f2 are closely spaced near a mine resonance and a laser Doppler vibrometer profiles the surface. In profiling, certain combination frequencies have a much greater contrast ratio than the linear profiles at f1 and f2-but off the mine some nonlinearity exists. Near resonance, the bending (a softening) of a family of tuning curves (over the mine) exhibits a linear relationship between peak velocity and corresponding frequency, which is characteristic of nonlinear mesoscopic elasticity effects that are observed in geomaterials like rocks or granular media. Results are presented for inert plastic VS 1.6, VS 2.2 and M14 mines buried 3.6 cm in loose soil. Tuning curves for a rigid mass plate resting on a soil layer exhibit similar results, suggesting that nonresonant conditions off the mine are desirable. [Work supported by U.S. Army RDECOM, CERDEC, NVESD, Fort Belvoir, VA.

  7. Observations of near-inertial waves in acoustic Doppler current profiler measurements made during the Mixed Layer Dynamics Experiment

    NASA Astrophysics Data System (ADS)

    Chereskin, T. K.; Levine, M. D.; Harding, A. J.; Regier, L. A.

    1989-06-01

    Measurements of upper ocean shear made during the Mixed Layer Dynamics Experiment (MILDEX) provide evidence of large horizontal scale motion at near-inertial frequency. The measurements consist of shipboard acoustic Doppler current profiles. Four large-scale spatial surveys of 2-4 days duration were made by the R/V Wecoma as a set of boxes approximately 60 km per side around a drifting current meter buoy. Velocity time series from the drifting buoy and from sonar measurements made from FLIP also indicated the presence of motions at near-inertial frequency. Horizontal length and time scales of the motion are estimated from the phase of the shear vector measured during the spatial surveys. Estimates of the length scale of the waves range from 500 to 1000 km, and the frequency is approximately 1.1f. The behavior of the phase is found to be consistent with a model of narrow-band inertial waves with vertical structure such that there is a zero crossing in velocity at the base of the mixed layer (40-60 m).

  8. Comparison of experiment and models of geodesic acoustic mode frequency and amplitude geometric scaling in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Simon, P.; Conway, G. D.; Stroth, U.; Biancalani, A.; Palermo, F.; the ASDEX Upgrade Team

    2016-04-01

    In a set of dedicated ASDEX Upgrade shape-scan experiments, the influence of plasma geometry on the frequency and amplitude behaviour of the geodesic acoustic mode (GAM), measured by Doppler reflectometry, is studied. In both limiter and divertor configurations, the plasma elongation was varied between circular and highly elongated states (1.1<κ <1.8 ). Also, the edge safety factor was scanned between 3  <  q  <  5. The GAM frequency {ω\\text{GAM}} and amplitude are used to test several models (heuristic, fluid and gyrokinetic based), which incorporate various plasma geometry effects. The experimentally observed effect of decreasing {ω\\text{GAM}} with increasing κ is predicted by most models. Other geometric factors, such as inverse aspect ratio ε and Shafranov shift gradient {Δ\\prime} are also seen to be influential in determining a reliable lower {ω\\text{GAM}} boundary. The GAM amplitude is found to vary with boundary elongation {κ\\text{b}} and safety factor q. The collisional damping is compared to multiple models for the collisionless damping. Collisional damping appears to play a stronger role in the divertor configuration, while collisional and collisionless damping both may contribute to the GAM amplitude in the limiter configuration.

  9. The experiment on the protein exposed to acoustic wave in model of hair cells.

    PubMed

    Takeda, H

    1976-01-01

    Why do animals have intense troubles mainly in the basal turns of their cochleae by exposure to sound and the ototoxity? I thought that the protein in cells had an important relation to this subject. So I performed this experiment. I made model of hair cells of silicon and poured three kinds of solutions of protein into them. And I checked the ionization of the protein and its denaturation by giving strong energy of oscillation to them like the same idea of photoelectric effect. As the result, as for the protein liquid, I noticed the increase of volts just after it was exposed to sound and about 3 hours later, I observed the figure decreased gradually. From this phenomenon, I presumed that the protein in sensory cells became a factor of the stimulation by receiving strong energy conversely. Low-percent protein liquid had less effect caused by sound. PMID:7097

  10. Community Involvement among Behaviourally Bisexual Men in the Midwestern USA: Experiences and Perceptions across Communities

    PubMed Central

    Dodge, Brian; Schnarrs, Phillip W.; Reece, Michael; Goncalves, Gabriel; Martinez, Omar; Nix, Ryan; Malebranche, David; Van Der Pol, Barbara; Murray, Maresa; Fortenberry, J. Dennis

    2012-01-01

    Limited research exists regarding community involvement and social support among behaviourally bisexual men. Previous studies suggest that bisexual men experience high levels of social stigma in both heterosexual and homosexual community settings. Research focusing on social support has demonstrated that individuals with limited access to similar individuals experience greater risk for negative health outcomes. Using a community-based research design, participants were recruited using multiple methods in Indianapolis, Indiana, USA. Researchers conducted in-depth, semi-structured interviews with 75 men who reported having engaged in bisexual behaviour within the past six months. Interviews elucidated the experiences of behaviourally bisexual men in heterosexual and homosexual settings, as well as their perceptions of the existence of a bisexual community or bisexual spaces. All participants perceived a lack of a visible bisexual community and expressed difficulty with being comfortable, or feeling belonging, within a variety of heterosexual and homosexual community spaces. Findings suggest the need for interventions focused on community building among, as well as creating spaces specifically designed for, bisexual men in order to increase perceived social support and decrease isolation and possible negative health outcomes. PMID:22978551

  11. Acoustic emission monitoring of hydraulic fracturing laboratory experiment with supercritical and liquid CO2

    NASA Astrophysics Data System (ADS)

    Ishida, Tsuyoshi; Aoyagi, Kazuhei; Niwa, Tomoya; Chen, Youqing; Murata, Sumihiko; Chen, Qu; Nakayama, Yoshiki

    2012-08-01

    Carbon dioxide (CO2) is often used for enhanced oil recovery in depleted petroleum reservoirs, and its behavior in rock is also of interest in CO2 capture and storage projects. CO2 usually becomes supercritical (SC-CO2) at depths greater than 1,000 m, while it is liquid (L-CO2) at low temperatures. The viscosity of L-CO2 is one order lower than that of normal liquid water, and that of SC-CO2 is much lower still. To clarify fracture behavior induced with injection of the low viscosity fluids, we conducted hydraulic fracturing experiments using 17 cm cubic granite blocks. The AE sources with the SC- and L-CO2 injections tend to distribute in a larger area than those with water injection, and furthermore, SC-CO2 tended to generate cracks extending more three dimensionally rather than along a flat plane than L-CO2. It was also found that the breakdown pressures for SC- and L-CO2 injections are expected to be considerably lower than for water.

  12. Evaluation of a scale-model experiment to investigate long-range acoustic propagation

    NASA Technical Reports Server (NTRS)

    Parrott, Tony L.; Mcaninch, Gerry L.; Carlberg, Ingrid A.

    1987-01-01

    Tests were conducted to evaluate the feasibility of using a scale-model experiment situated in an anechoic facility to investigate long-range sound propagation over ground terrain. For a nominal scale factor of 100:1, attenuations along a linear array of six microphones colinear with a continuous-wave type of sound source were measured over a wavelength range from 10 to 160 for a nominal test frequency of 10 kHz. Most tests were made for a hard model surface (plywood), but limited tests were also made for a soft model surface (plywood with felt). For grazing-incidence propagation over the hard surface, measured and predicted attenuation trends were consistent for microphone locations out to between 40 and 80 wavelengths. Beyond 80 wavelengths, significant variability was observed that was caused by disturbances in the propagation medium. Also, there was evidence of extraneous propagation-path contributions to data irregularities at more remote microphones. Sensitivity studies for the hard-surface and microphone indicated a 2.5 dB change in the relative excess attenuation for a systematic error in source and microphone elevations on the order of 1 mm. For the soft-surface model, no comparable sensitivity was found.

  13. Acoustic measurements from a rotor blade-vortex interaction noise experiment in the German-Dutch Wind Tunnel (DNW)

    NASA Technical Reports Server (NTRS)

    Martin, Ruth M.; Splettstoesser, W. R.; Elliott, J. W.; Schultz, K.-J.

    1988-01-01

    Acoustic data are presented from a 40 percent scale model of the 4-bladed BO-105 helicopter main rotor, measured in the large European aeroacoustic wind tunnel, the DNW. Rotor blade-vortex interaction (BVI) noise data in the low speed flight range were acquired using a traversing in-flow microphone array. The experimental apparatus, testing procedures, calibration results, and experimental objectives are fully described. A large representative set of averaged acoustic signals is presented.

  14. Generation of Acoustic-Gravity Waves in Ionospheric HF Heating Experiments: Simulating Large-Scale Natural Heat Sources

    NASA Astrophysics Data System (ADS)

    Pradipta, Rezy

    In this thesis, we investigate the potential role played by large-scale anomalous heat sources (e.g. prolonged heat wave events) in generating acoustic-gravity waves (AGWs) that might trigger widespread plasma turbulence in the ionospheric layer. The main hypothesis is that, the thermal gradients associated with the heat wave fronts could act as a source of powerful AGW capable of triggering ionospheric plasma turbulence over extensive areas. In our investigations, first we are going to examine a case study of the summer 2006 North American heat wave event. Our examination of GPS-derived total electron content (TEC) data over the North American sector reveals a quite noticeable increase in the level of daily plasma density fluctuations during the summer 2006 heat wave period. Comparison with the summer 2005 and summer 2007 data further confirms that the observed increase of traveling ionospheric disturbances (TIDs) during the summer 2006 heat wave period was not simply a regular seasonal phenomenon. Furthermore, a series of field experiments had been carried out at the High-frequency Active Auroral Research Program (HAARP) facility in order to physically simulate the process of AGW/TID generation by large-scale thermal gradients in the ionosphere. In these ionospheric HF heating experiments, we create some time-varying artificial thermal gradients at an altitude of 200--300 km above the Earth's surface using vertically-transmitted amplitude-modulated 0-mode HF heater waves. For our experiments, a number of radio diagnostic instruments had been utilized to detect the characteristic signatures of heater-generated AGW/TID. So far, we have been able to obtain several affirmative indications that some artificial AGW/TID are indeed being radiated out from the heated plasma volume during the HAARP-AGW experiments. Based on the experimental evidence, we may conclude that it is certainly quite plausible for large-scale thermal gradients associated with severe heat wave

  15. The Experiences and Perceptions of Street-Involved Youth Regarding Emergency Department Services.

    PubMed

    Nicholas, David B; Newton, Amanda S; Calhoun, Avery; Dong, Kathryn; deJong-Berg, Margaret A; Hamilton, Faye; Kilmer, Christopher; McLaughlin, Anne Marie; Shankar, Janki

    2016-05-01

    Street-involved (SI) youth comprise a substantial component of the urban homeless population. Despite being significant users of hospital emergency department (ED) services for acute and ongoing health needs, little is known about their experiences of ED care and the factors affecting their ED use. This study used a grounded theory and community-based approach to examine these issues. Focus groups and individual interviews were facilitated with 48 SI youth between ages 15 and 26 years, recruited in hospital or through community agencies serving SI youth in a major Western Canadian city. Results demonstrate that SI youth often perceived suboptimal care and experienced long waiting periods that led to many avoiding or prematurely exiting the ED. Service gaps appeared to have a negative bearing on their care and health outcomes. Findings invite a critical review of ED care processes, structures, and staff interactions in the aim of enhancing ED services to SI youth. PMID:25829466

  16. Age, flight experience, and risk of crash involvement in a cohort of professional pilots.

    PubMed

    Li, Guohua; Baker, Susan P; Grabowski, Jurek G; Qiang, Yandong; McCarthy, Melissa L; Rebok, George W

    2003-05-15

    Federal aviation regulations prohibit airline pilots from flying beyond the age of 60 years. However, the relation between pilot age and flight safety has not been rigorously assessed using empirical data. From 1987 to 1997, the authors followed a cohort of 3,306 commuter air carrier and air taxi pilots who were aged 45-54 years in 1987. During the follow-up period, the pilots accumulated a total of 12.9 million flight hours and 66 aviation crashes, yielding a rate of 5.1 crashes per million pilot flight hours. Crash risk remained fairly stable as the pilots aged from their late forties to their late fifties. Flight experience, as measured by total flight time at baseline, showed a significant protective effect against the risk of crash involvement. With adjustment for age, pilots who had 5,000-9,999 hours of total flight time at baseline had a 57% lower risk of a crash than their less experienced counterparts (relative risk = 0.43, 95% confidence interval: 0.21, 0.87). The protective effect of flight experience leveled off after total flight time reached 10,000 hours. The lack of an association between pilot age and crash risk may reflect a strong "healthy worker effect" stemming from the rigorous medical standards and periodic physical examinations required for professional pilots. PMID:12746239

  17. Evaluation of Wave Propagation Properties during a True-Triaxial Rock Fracture Experiment using Acoustic Emission Frequency Characteristics

    NASA Astrophysics Data System (ADS)

    Goodfellow, S. D.; Ghofrani Tabari, M.; Nasseri, M. B.; Young, R.

    2013-12-01

    A true-triaxial deformation experiment was conducted to study the evolution of wave propagation properties by using frequency characteristics of AE waveforms to diagnose the state of fracturing in a sample of sandstone. Changes in waveform frequency content has been interpreted as either the generation of progressively larger fractures or the relative attenuation of high-frequency wave components as a result of micro-crack formation. A cubic sample of Fontainebleau sandstone was initially loaded to a stress state of σ1 = σ2 = 35 MPa, σ3 = 5 MPa at which point σ1¬ was increased until failure. Acoustic emission (AE) activity was monitored by 18 PZT transducers, three embedded in each platen. The sensor amplitude response spectrum was determined by following an absolute source calibration procedure and showed a relatively constant sensitivity in the frequency range between 20 kHz and 1200 kHz. Amplified waveforms were continuously recorded at a sampling rate of 10 MHz and 12-bit resolution. Continuous acoustic emission waveforms were harvested to extract discrete events. Using a time-varying transverse isotropic velocity model, 48,502 events were locatable inside the sample volume. Prior to peak-stress, AE activity was associated with stable quasi-static growth of fractures coplanar with σ1 and σ2 located near the platen boundaries. In the post peak-stress regime, fracture growth displays unstable ¬dynamic propagation. Analysis of waveform frequency characteristics was limited to the pre peak-stress regime. Analysis of AE frequency characteristics was conducted on all 48,502 located AE events; each event file containing 18 waveforms of varied quality. If the signal to noise ratio was greater than 5, the waveforms power spectrum was estimated and the source-receiver raypath vector was calculated. The power spectrum of each waveform was divided into three frequency bands (Low: 100 - 300 kHz, Medium: 300 - 600 kHz and High: 600 - 1000 kHz) and the power in each

  18. Seismic moment tensors of acoustic emissions recorded during laboratory rock deformation experiments: sensitivity to attenuation and anisotropy

    NASA Astrophysics Data System (ADS)

    Stierle, Eva; Vavryčuk, Václav; Kwiatek, Grzegorz; Charalampidou, Elli-Maria; Bohnhoff, Marco

    2016-04-01

    Seismic moment tensors can provide information on the size and orientation of fractures producing acoustic emissions (AEs) and on the stress conditions in the sample. The moment tensor inversion of AEs is, however, a demanding procedure requiring carefully calibrated sensors and accurate knowledge of the velocity model. In field observations, the velocity model is usually isotropic and time independent. In laboratory experiments, the velocity is often anisotropic and time dependent and attenuation might be significant due to opening or closure of microcracks in the sample during loading. In this paper, we study the sensitivity of the moment tensor inversion to anisotropy of P-wave velocities and attenuation. We show that retrieved moment tensors critically depend on anisotropy and attenuation and their neglect can lead to misinterpretations of the source mechanisms. The accuracy of the inversion also depends on the fracturing mode of AEs: tensile events are more sensitive to P-wave anisotropy and attenuation than shear events. We show that geometry of faulting in anisotropic rocks should be studied using the source tensors, since the P- and T-axes of the moment tensors are affected by velocity anisotropy and deviate from the true orientation of faulting. The stronger the anisotropy is, the larger the deviations are. Finally, we prove that the moment tensor inversion applied to a large dataset of AEs can be utilized to provide information on the attenuation parameters of the rock sample. The method is capable of measuring anisotropic attenuation in the sample and allows for detection of dilatant cracking according to the stress regime.

  19. Student design projects in applied acoustics.

    PubMed

    Bös, Joachim; Moritz, Karsten; Skowronek, Adam; Thyes, Christian; Tschesche, Johannes; Hanselka, Holger

    2012-03-01

    This paper describes a series of student projects which are intended to complement theoretical education in acoustics and engineering noise control with practical experience. The projects are also intended to enhance the students' ability to work in a team, to manage a project, and to present their results. The projects are carried out in close cooperation with industrial partners so that the students can get a taste of the professional life of noise control engineers. The organization of such a project, its execution, and some of the results from the most recent student project are presented as a demonstrative example. This latest project involved the creation of noise maps of a production hall, the acoustic analysis of a packaging machine, and the acoustic analysis of a spiral vibratory conveyor. Upon completion of the analysis, students then designed, applied, and verified some simple preliminary noise reduction measures to demonstrate the potential of these techniques. PMID:22423803

  20. Numerical simulations of impacts involving porous bodies. II. Comparison with laboratory experiments

    NASA Astrophysics Data System (ADS)

    Jutzi, Martin; Michel, Patrick; Hiraoka, Kensuke; Nakamura, Akiko M.; Benz, Willy

    2009-06-01

    In this paper, we compare the outcome of high-velocity impact experiments on porous targets, composed of pumice, with the results of simulations by a 3D SPH hydrocode in which a porosity model has been implemented. The different populations of small bodies of our Solar System are believed to be composed, at least partially, of objects with a high degree of porosity. To describe the fragmentation of such porous objects, a different model is needed than that used for non-porous bodies. In the case of porous bodies, the impact process is not only driven by the presence of cracks which propagate when a stress threshold is reached, it is also influenced by the crushing of pores and compaction. Such processes can greatly affect the whole body's response to an impact. Therefore, another physical model is necessary to improve our understanding of the collisional process involving porous bodies. Such a model has been developed recently and introduced successfully in a 3D SPH hydrocode [Jutzi, M., Benz, W., Michel, P., 2008. Icarus 198, 242-255]. Basic tests have been performed which already showed that it is implemented in a consistent way and that theoretical solutions are well reproduced. However, its full validation requires that it is also capable of reproducing the results of real laboratory impact experiments. Here we present simulations of laboratory experiments on pumice targets for which several of the main material properties have been measured. We show that using the measured material properties and keeping the remaining free parameters fixed, our numerical model is able to reproduce the outcome of these experiments carried out under different impact conditions. This first complete validation of our model, which will be tested for other porous materials in the future, allows us to start addressing problems at larger scale related to small bodies of our Solar System, such as collisions in the Kuiper Belt or the formation of a family by the disruption of a porous

  1. 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 ...

  2. Analysis of existing data from a Distributed Acoustic Sensing experiment at Garner Valley, California using noise correlation functions (PoroTomo Substask 3.2)

    DOE Data Explorer

    Xiangfang Zeng

    2015-03-26

    In September 2013, an experiment using Distributed Acoustic Sensing (DAS) was conducted at Garner Valley, a test site of the University of California Santa Barbara (Lancelle et al., 2014). This submission includes noise cross-correlation functions (NCF) . Each file includes a NCF between two channels. The name of each channel denotes the distance in meters from starting point of the fiber-optic cable. Lancelle, C., N. Lord, H. Wang, D. Fratta, R. Nigbor, A. Chalari, R. Karaulanov, J. Baldwin, and E. Castongia (2014), Directivity and Sensitivity of Fiber-Optic Cable Measuring Ground Motion using a Distributed Acoustic Sensing Array (abstract # NS31C-3935), AGU Fall Meeting. 
https://agu.confex.com/agu/fm14/meetingapp.cgi#Paper/19828 The e-poster is available at: https://agu.confex.com/data/handout/agu/fm14/Paper_19828_handout_696_0.pdf

  3. Acoustic signal associated with the bursting of a soap film which initially closes an overpressurized cavity . Experiment and theory

    NASA Astrophysics Data System (ADS)

    Vidal, V.; Géminard, J.-C.; Divoux, T.; Melo, F.

    2006-12-01

    We report an experimental study of the sound produced by the bursting of a thin liquid film, which initially closes an overpressurized cylindrical cavity. There is a need for a deep understanding of the phenomenon, which can be very useful in numerous practical cases. For instance, in the nature, the volcanologists observe the bursting of large, elongated, gas-bubbles at the surface of lava lakes and record the associated sound emission. One can wonder which pieces of information they can get from such acoustic measurements. For a didactic purpose, we provide also the reader with all the theoretical background necessary for the understanding of the physical processes that govern the various characteristics of the acoustic signals: the cavity geometry governs the frequency; the viscous dissipation and the radiation are responsible for the damping; the acoustic energy informs about the characteristic time associated with the film-rupture more than about the energy initially loaded in the cavity.

  4. Varieties of Musical Experience

    ERIC Educational Resources Information Center

    Bharucha, J. Jamshed; Curtis, Meagan; Paroo, Kaivon

    2006-01-01

    In this paper, we argue that music cognition involves the use of acoustic and auditory codes to evoke a variety of conscious experiences. The variety of domains that are encompassed by music is so diverse that it is unclear whether a single domain of structure or experience is defining. Music is best understood as a form of communication in which…

  5. The Role of Student Support Services in Encouraging Student Involvement and Its Impact on Student Perceptions and Academic Experiences

    ERIC Educational Resources Information Center

    Kelley-Hall, Caren

    2010-01-01

    The purpose of this study was to explore the role of Student Support Services (SSS) in encouraging student involvement and its impact on student perceptions and academic experiences in three technical colleges in upstate South Carolina. By examining Alexander Astin's theory of student involvement in the services provided by the program, a better…

  6. Acoustic habitat and shellfish mapping and monitoring in shallow coastal water - Sidescan sonar experiences in The Netherlands

    NASA Astrophysics Data System (ADS)

    van Overmeeren, Ronnie; Craeymeersch, Johan; van Dalfsen, Jan; Fey, Frouke; van Heteren, Sytze; Meesters, Erik

    2009-11-01

    Sidescan sonar has been applied in a number of shallow water environments along the Dutch coast to map and monitor shellfish and seabed habitats. The littoral setting of these surveys may hamper data acquisition flying the towfish in zones of turbulence and waves, but also offers valuable opportunities for understanding, interpreting and validating sidescan sonar images because of the ability to ground-truth during low water periods, enabling easy identification and validation. Acoustical images of some of the mussel banks on the tidal flats of the Wadden Sea, recorded at high tide, show a marked resemblance with optical Google Earth images of the same banks. These sonar images may thus serve as ' acoustic type signatures' for the interpretation of sonar patterns recorded in deeper water where ground-truthing is more difficult and more expensive. Similarly, acoustic type signatures of (Japanese) oyster banks were obtained in the estuaries in the southwest of the Netherlands. Automated acoustic pattern recognition of different habitats and acoustical estimation of faunal cover and density are possible applications of sidescan sonar. Both require that the backscattering observed on the sidescan sonar images is directly caused by the biological component of the seafloor. Filtering offers a simple and effective pre-processing technique to separate the faunal signals from linear trends such as emanating from wave ripples or the central tracks of the towfish. Acoustically estimating the faunal density is approached by in-situ counting peaks in backscattering in unit squares. These counts must be calibrated by ground-truthing. Ground-truthing on littoral mussel banks in the Wadden Sea has been carried out by measuring their cover along lines during low tide. Due to its capacity of yielding full-cover, high resolution images of large surfaces, sidescan sonar proves to be an excellent, cost-effective tool for quantitative time-lapse monitoring of habitats.

  7. 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.

  8. 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.

  9. Investigating the use of patient involvement and patient experience in quality improvement in Norway: rhetoric or reality?

    PubMed Central

    2013-01-01

    Background Patient involvement in health care decision making is part of a wider trend towards a more bottom-up approach to service planning and provision, and patient experience is increasingly conceptualized as a core dimension of health care quality. The aim of this multi-level study is two-fold: 1) to describe and analyze how governmental organizations expect acute hospitals to incorporate patient involvement and patient experiences into their quality improvement (QI) efforts and 2) to analyze how patient involvement and patient experiences are used by hospitals to try to improve the quality of care they provide. Methods This multi-level case study combines analysis of national policy documents and regulations at the macro level with semi-structured interviews and non-participant observation of key meetings and shadowing of staff at the meso and micro levels in two purposively sampled Norwegian hospitals. Fieldwork at the meso and micro levels was undertaken over a 12-month period (2011–2012). Results Governmental documents and regulations at the macro level demonstrated wide-ranging expectations for the integration of patient involvement and patient experiences in QI work in hospitals. The expectations span from systematic collection of patients’ and family members’ experiences for the purpose of improving service quality through establishing patient-oriented arenas for ongoing collaboration with staff to the support of individual involvement in decision making. However, the extent of involvement of patients and application of patient experiences in QI work was limited at both hospitals. Even though patient involvement was gaining prominence at the meso level − and to a lesser extent at the micro level − relevant tools for measuring and using patient experiences in QI work were lacking, and available measures of patient experience were not being used meaningfully or systematically. Conclusions The relative lack of expertise in Norwegian hospitals of

  10. Sharing decisions in consultations involving anti-psychotic medication: a qualitative study of psychiatrists' experiences.

    PubMed

    Seale, Clive; Chaplin, Robert; Lelliott, Paul; Quirk, Alan

    2006-06-01

    In psychiatry, and in treating people with a diagnosis of schizophrenia in particular, there are obstacles to achieving concordant, shared decision making and in building a co-operative therapeutic alliance where mutual honesty is the norm. Studies of people with a diagnosis of schizophrenia have revealed critical views of medical authority, particularly over the issue of enforced compliance with antipsychotic medication. Psychiatrists are known to place particular value on such medication. This qualitative study reports the views of 21 general adult psychiatrists working in UK about their experiences of consultations involving discussion of antipsychotic medication. Interviewees reported a general commitment to achieving concordant relationships with patients and described a number of strategies they used to promote this. In this respect, their self-perception differs from the picture of authoritarian practice painted by critics of psychiatry, and by some studies reporting patients' views. Interviewees also described obstacles to achieving concordance, including adverse judgements of patients' competence and honesty about their medication use. Explaining the adverse effects of medication was perceived to discourage some patients from accepting this treatment. Moments of strategic dishonesty were reported. Psychiatrists perceived that trust could be damaged by episodes of coercion, or by patients' perception of coercive powers. We conclude that a self-perception of patient-centredness may not preclude psychiatrists from fulfilling a social control function. PMID:16343722

  11. House Staff Quality Council: One Institution's Experience to Integrate Resident Involvement in Patient Care Improvement Initiatives

    PubMed Central

    Dixon, Jennifer L.; Papaconstantinou, Harry T.; Erwin, John P.; McAllister, Russell Keith; Berry, Tiffany; Wehbe-Janek, Hania

    2013-01-01

    Background Residents and fellows perform a large portion of the hands-on patient care in tertiary referral centers. As frontline providers, they are well suited to identify quality and patient safety issues. As payment reform shifts hospitals to a fee-for-value–type system with reimbursement contingent on quality outcomes, preventive health, and patient satisfaction, house staff must be intimately involved in identifying and solving care delivery problems related to quality, outcomes, and patient safety. Many challenges exist in integrating house staff into the quality improvement infrastructure; these challenges may ideally be managed by the development of a house staff quality council (HSQC). Methods Residents and fellows at Scott & White Memorial Hospital interested in participating in a quality council submitted an application, curriculum vitae, and letter of support from their program director. Twelve residents and fellows were selected based on their prior quality improvement experience and/or their interest in quality and safety initiatives. Results In only 1 year, our HSQC, an Alliance of Independent Academic Medical Centers National Initiative III project, initiated 3 quality projects and began development of a fourth project. Conclusion Academic medical centers should consider establishing HSQCs to align institutional quality goals with residency training and medical education. PMID:24052771

  12. Experience, Adoption, and Technology: Exploring the Phenomenological Experiences of Faculty Involved in Online Teaching at One School of Public Health

    ERIC Educational Resources Information Center

    Kidd, Terry; Davis, Trina; Larke, Patricia

    2016-01-01

    Using the Unified Theory of Acceptance and Use of Technology (UTAUT) and Dewey's Theory of Experience, this phenomenological study explored the experiences of faculty who engaged in online teaching at one school of public health. Findings revealed that the experiences of public health faculty, who engaged in online teaching, are similar and…

  13. Teenagers' Significant Experiences in Areas of Arts: A Study of the Subjectively Felt Impact and Some Qualitative Aspects of Experiences Involving Productive Arts Activities

    ERIC Educational Resources Information Center

    Finnas, Leif

    2012-01-01

    As a part of a larger project, this study focused primarily on Finland-Swedish ninth-graders' "productive" arts experiences (involving music-making, acting, writing, painting/drawing, dancing), as these had been reported when the pupils had been asked to write down descriptions of "strong" experiences in arts areas (music, dramatic art, literature…

  14. A Phenomenological Study of Parental Involvement and the Undergraduate College Student Experience

    ERIC Educational Resources Information Center

    Garrison, David Michael

    2013-01-01

    Parents highly involved in the academic lives of their college-going children have become increasingly common and yet the effect of such involvement on students is poorly understood by student services administrators and faculty. The purpose of this study was to better define the phenomenon of parental involvement in college through an…

  15. Comparative Analysis of Continuous Acoustic Emission (AE) Data, Acquired from 12 and 16 Bit Streaming Systems during Rock Deformation Experiments

    NASA Astrophysics Data System (ADS)

    Flynn, J.; Goodfellow, S. D.; Nasseri, M. H.; Reyes-Montes, J. M.; Young, R.

    2013-12-01

    A comparative analysis of continuous acoustic emission (AE) data acquired during a triaxial compression test, using a 12-bit and a 16-bit acquisition system, is presented. A cylindrical sample (diameter 50.1 mm and length 125 mm) of Berea sandstone was triaxally deformed at a confining pressure of 15 MPa and a strain rate of 1.6E-06 s-1. The sample was loaded differentially until failure occurred at approximately σ1 = 160 MPa. AE activity was monitored for the duration of the experiment by an array of 8 broadband piezoelectric transducers coupled to the rock sample. Raw signals were amplified by 40 dB using pre-amplifiers equipped with filter modules with a frequency passband of 100 kHz to 1 MHz. The amplifiers had a split output enabling the measured signal to be fed into a 12-bit and a 16-bit acquisition system. AE waveforms were continuously recorded at 10 MS/s on 8 data acquisition channels per system. Approximately 4,500 events were harvested and source located from the continuous data for each system. P-wave arrivals were automatically picked and event locations calculated using the downhill Simplex method and a time-varying transverse isotropic velocity model based on periodical surveys across the sample. Events detected on the 12-bit and 16-bit systems were compared both in terms of their P-wave picks and their source locations. In the early stages of AE activity, there appeared to be little difference between P-wave picks and hypocenter locations from both data sets. As the experiment progressed into the post-peak stress regime, which was accompanied by an increase in AE rate and amplitude, fewer events could be harvested from the 12-bit data compared to the 16-bit data. This is linked to the observation of a higher signal-to-noise ratio on AE waveforms harvested from the 16-bit stream compared to those from the 12-bit stream, which results in an easier identification of P-wave onsets. Similarly a higher confidence in source location is expected. Analysis

  16. Propellant injection strategy for suppressing acoustic combustion instability

    NASA Astrophysics Data System (ADS)

    Diao, Qina

    Shear-coaxial injector elements are often used in liquid-propellant-rocket thrust chambers, where combustion instabilities remain a significant problem. A conventional solution to the combustion instability problem relies on passive control techniques that use empirically-developed hardware such as acoustic baffles and tuned cavities. In addition to adding weight and decreasing engine performance, these devices are designed using trial-and-error methods, which do not provide the capability to predict the overall system stability characteristics in advance. In this thesis, two novel control strategies that are based on propellant fluid dynamics were investigated for mitigating acoustic instability involving shear-coaxial injector elements. The new control strategies would use a set of controlled injectors allowing local adjustment of propellant flow patterns for each operating condition, particularly when instability could become a problem. One strategy relies on reducing the oxidizer-fuel density gradient by blending heavier methane with the main fuel, hydrogen. Another strategy utilizes modifying the equivalence ratio to affect the acoustic impedance through mixing and reaction rate changes. The potential effectiveness of these strategies was assessed by conducting unit-physics experiments. Two different model combustors, one simulating a single-element injector test and the other a double-element injector test, were designed and tested for flame-acoustic interaction. For these experiments, the Reynolds number of the central oxygen jet was kept between 4700 and 5500 making the injector flames sufficiently turbulent. A compression driver, mounted on one side of the combustor wall, provided controlled acoustic excitation to the injector flames, simulating the initial phase of flame-acoustic interaction. Acoustic excitation was applied either as band-limited white noise forcing between 100 Hz and 5000 Hz or as single-frequency, fixed-amplitude forcing at 1150 Hz

  17. 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.

  18. Acoustics of a Nonhomogeneous Moving Medium.

    NASA Technical Reports Server (NTRS)

    Blokhintsev, D I

    1956-01-01

    Theoretical basis of the acoustics of a moving nonhomogeneous medium is considered in this report. Experiments that illustrate or confirm some of the theoretical explanation or derivation of these acoustics are also included.

  19. Mode-locking of acoustic resonators and its application to vibration cancellation in acoustic heat engines

    SciTech Connect

    Spoor, P.S.; Swift, G.W. )

    1999-09-01

    Vibration induced in engine hardware by a working fluid can be very significant in high-power, high-amplitude acoustic heat engines, and is a serious impediment to their practical use. This vibration can cause fatigue and destruction of engine components as well as fuel lines, cooling lines, and sensor wires. The forces involved make anchoring such an engine to an [open quotes]immovable[close quotes] object impractical. Rigidly attaching two such engines together, and acoustically coupling them with a duct of such a length and diameter that the two engines mode-lock in antiphase (thus canceling the longitudinal vibration) appears to be an inexpensive, viable solution. This paper describes in detail experiments demonstrating the feasibility of this idea, and the underlying theory. [copyright] [ital 1999 Acoustical Society of America.] < --[HEB] -->

  20. Estimation of Effect Size from a Series of Experiments Involving Paired Comparisons.

    ERIC Educational Resources Information Center

    Gibbons, Robert D.; And Others

    1993-01-01

    A distribution theory is derived for a G. V. Glass-type (1976) estimator of effect size from studies involving paired comparisons. The possibility of combining effect sizes from studies involving a mixture of related and unrelated samples is also explored. Resulting estimates are illustrated using data from previous psychiatric research. (SLD)

  1. Addiction Treatment Experience among a Cohort of Street-Involved Youths and Young Adults

    ERIC Educational Resources Information Center

    Wong, Jellena; Marshall, Brandon D. L.; Kerr, Thomas; Lai, Calvin; Wood, Evan

    2009-01-01

    Very little is known about the accessibility and potential barriers to addiction treatment among street youths and young adults. We sought to examine the prevalence and correlates of enrollment in addiction treatment among a cohort of street-involved youths and young adults in Vancouver, Canada. Street-involved youths and young adults who use…

  2. Effect of reflected and refracted signals on coherent underwater acoustic communication: results from the Kauai experiment (KauaiEx 2003).

    PubMed

    Rouseff, Daniel; Badiey, Mohsen; Song, Aijun

    2009-11-01

    The performance of a communications equalizer is quantified in terms of the number of acoustic paths that are treated as usable signal. The analysis uses acoustical and oceanographic data collected off the Hawaiian Island of Kauai. Communication signals were measured on an eight-element vertical array at two different ranges, 1 and 2 km, and processed using an equalizer based on passive time-reversal signal processing. By estimating the Rayleigh parameter, it is shown that all paths reflected by the sea surface at both ranges undergo incoherent scattering. It is demonstrated that some of these incoherently scattered paths are still useful for coherent communications. At range of 1 km, optimal communications performance is achieved when six acoustic paths are retained and all paths with more than one reflection off the sea surface are rejected. Consistent with a model that ignores loss from near-surface bubbles, the performance improves by approximately 1.8 dB when increasing the number of retained paths from four to six. The four-path results though are more stable and require less frequent channel estimation. At range of 2 km, ray refraction is observed and communications performance is optimal when some paths with two sea-surface reflections are retained. PMID:19894819

  3. 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.

  4. 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

  5. New high-order, semi-implicit Hybridized Discontinuous Galerkin - Spectral Element Method (HDG-SEM) for simulation of complex wave propagation involving coupling between seismic, hydro-acoustic and infrasonic waves: numerical analysis and case studies.

    NASA Astrophysics Data System (ADS)

    Terrana, S.; Vilotte, J. P.; Guillot, L.

    2015-12-01

    New seismological monitoring networks combine broadband seismic receivers, hydrophones and micro-barometers antenna, providing complementary observation of source-radiated waves. Exploiting these observations requires accurate and multi-media - elastic, hydro-acoustic, infrasound - wave simulation methods, in order to improve our physical understanding of energy exchanges at material interfaces.We present here a new development of a high-order Hybridized Discontinuous Galerkin (HDG) method, for the simulation of coupled seismic and acoustic wave propagation, within a unified framework ([1],[2]) allowing for continuous and discontinuous Spectral Element Methods (SEM) to be used in the same simulation, with conforming and non-conforming meshes. The HDG-SEM approximation leads to differential - algebraic equations, which can be solved implicitly using energy-preserving time-schemes.The proposed HDG-SEM is computationally attractive, when compared with classical Discontinuous Galerkin methods, involving only the approximation of the single-valued traces of the velocity field along the element interfaces as globally coupled unknowns. The formulation is based on a variational approximation of the physical fluxes, which are shown to be the explicit solution of an exact Riemann problem at each element boundaries. This leads to a highly parallel and efficient unstructured and high-order accurate method, which can be space-and-time adaptive.A numerical study of the accuracy and convergence of the HDG-SEM is performed through a number of case studies involving elastic-acoustic (infrasound) coupling with geometries of increasing complexity. Finally, the performance of the method is illustrated through realistic case studies involving ground wave propagation associated to topography effects.In conclusion, we outline some on-going extensions of the method.References:[1] Cockburn, B., Gopalakrishnan, J., Lazarov, R., Unified hybridization of discontinuous Galerkin, mixed and

  6. Patient involvement in diabetes care: experiences in nine diabetes care groups

    PubMed Central

    de Bruin, Simone R.; Struijs, Jeroen N.; Rijken, Mieke; Nijpels, Giel; Baan, Caroline A.

    2015-01-01

    Introduction Despite the expected beneficial effects on quality of care, patient involvement in diabetes care groups, which deliver a bundled paid integrated care programme for diabetes type 2, seems to be limited. The aim of this study was to gain insight into levels and methods of patient involvement, into facilitators and barriers, and into the future preferences of care groups and patient representatives. Theory and methods Semi-structured interviews were held with 10 representatives of care groups and 11 representatives of patient advocacy groups. An adapted version of Arnstein's ladder of citizen participation was used to define five levels of patient involvement. Results Patient involvement in care groups was mostly limited to informing and consulting patients. Higher levels, i.e., advising, co-producing and decision-making, were less frequently observed. Care groups and patient representatives perceived largely the same barriers and facilitators and had similar preferences regarding future themes and design of patient involvement. Conclusion Constructive collaboration between diabetes care groups and patient representatives to enhance patient involvement in the future seems viable. Several issues such as the lack of evidence for effectiveness of patient involvement, differences in viewpoints on the role and responsibilities of care groups and perceived barriers need to be addressed. PMID:27118961

  7. Central nervous system involvement in T-cell lymphoma: A single center experience.

    PubMed

    Gurion, Ronit; Mehta, Neha; Migliacci, Jocelyn C; Zelenetz, Andrew; Moskowitz, Alison; Lunning, Matthew; Moskowitz, Craig; Hamlin, Paul; Horwitz, Steven

    2016-05-01

    Background We characterized the incidence of central nervous system (CNS) involvement, risk factors and outcome in a large single institution dataset of peripheral T-cell lymphoma (PTCL). Methods Retrospective review of the PTCL database at Memorial Sloan Kettering Cancer Center. We identified 231 patients with any subtype of PTCL between 1994-2011 with a minimum six months of follow-up or an event defined as relapse or death. Results Histologies included peripheral T-cell lymphoma-not otherwise specified (PTCL-NOS) (31.6%), angioimmunoblastic (16.9%), anaplastic large cell lymphoma (ALCL), ALK- (12.1%), ALCL, ALK + (6.1%), extranodal NK/T-cell lymphoma (7.4%), adult T-cell leukemia/lymphoma (ATLL) (7.4%), and transformed mycosis fungoides (8.7%). Seventeen patients had CNS disease (7%). Fifteen had CNS involvement with PTCL and two had diffuse large B-cell lymphoma and glioblastoma. Median time to CNS involvement was 3.44 months (0.16-103.1). CNS prophylaxis was given to 24 patients (primarily intrathecal methotrexate). Rates of CNS involvement were not different in patients who received prophylaxis. Univariate analysis identified stage III-IV, bone marrow involvement, >1 extranodal site and ATLL as risk factors for CNS disease. On multivariate analysis, >1 extranodal site and international prognostic index (IPI) ≥ 3 were predictive for CNS involvement. The median survival of patients with CNS involvement was 2.63 months (0.10-75). Conclusions Despite high relapse rates, PTCL, except ATLL, carries a low risk of CNS involvement. Prognosis with CNS involvement is poor and risk factors include: >1 extra nodal site and IPI ≥3. PMID:27046135

  8. Acoustic neuroma

    MedlinePlus

    Vestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor ... 177. Battista RA. Gamma knife radiosurgery for vestibular schwannoma. Otolaryngol Clin North Am . 2009;42:635-654. ...

  9. Calculation of Critical Experiments involving U(37)O2F2 Solution

    SciTech Connect

    Goluoglu, K.L.

    2006-03-03

    Critical experiments were conducted at the Oak Ridge Critical Experiment Facility (ORCEF) to determine the critical concentration for an unreflected 69.2-cm-diameter sphere of UO{sub 2}F{sub 2}, at an enrichment of {approx}37 percent U{sup 235}, by weight. These experiments were a continuation of previous efforts to determine critical dimensions for fissile materials in simple geometry. Some of the earlier experiments in this vessel have been published as part of the OECD handbook. The reports concerning these experiments have only recently become available. Until August 2005, Refs. 2 and 3 were still classified. These documents, along with experimental logbooks and unclassified papers available on the experimental campaign and facility are being used to generate a computer model for this critical experiment.

  10. Three atmospheric dispersion experiments involving oil fog plumes measured by lidar

    NASA Technical Reports Server (NTRS)

    Eberhard, W. L.; Mcnice, G. T.; Troxel, S. W.

    1986-01-01

    The Wave Propagation Lab. participated with the U.S. Environmental Protection Agency in a series of experiments with the goal of developing and validating dispersion models that perform substantially better that models currently available. The lidar systems deployed and the data processing procedures used in these experiments are briefly described. Highlights are presented of conclusions drawn thus far from the lidar data.

  11. A Classroom Experiment on Phase Equilibria Involving Orientational Disordering in Crystals.

    ERIC Educational Resources Information Center

    Mjojo, C. C.

    1985-01-01

    Background information, procedures used, and results obtained are provided for an experiment in which a phase diagram is determined using a differential scanning calorimeter. Commercial samples of D-camphoric anhydride (Eastman Kodak) and D,L-camphoric anhydride (Aldrich) were used in the experiment. (JN)

  12. Stakeholder Perceptions of the Positive Benefits and Critical Challenges Involved in Student Service-Learning Experiences

    ERIC Educational Resources Information Center

    Hohenthal, K. Darcy

    2010-01-01

    The Bolman and Deal (2003) Four-Frame Model was adapted in this qualitative phenomenological research study to describe how stakeholders experience student service-learning. The study presents how students perceive the positive benefits and critical challenges encountered in their service-learning experience; how professors perceive the positive…

  13. Involvement of Sensory Regions in Affective Experience: A Meta-Analysis

    PubMed Central

    Satpute, Ajay B.; Kang, Jian; Bickart, Kevin C.; Yardley, Helena; Wager, Tor D.; Barrett, Lisa F.

    2015-01-01

    A growing body of work suggests that sensory processes may also contribute to affective experience. In this study, we performed a meta-analysis of affective experiences driven through visual, auditory, olfactory, gustatory, and somatosensory stimulus modalities including study contrasts that compared affective stimuli to matched neutral control stimuli. We found, first, that limbic and paralimbic regions, including the amygdala, anterior insula, pre-supplementary motor area, and portions of orbitofrontal cortex were consistently engaged across two or more modalities. Second, early sensory input regions in occipital, temporal, piriform, mid-insular, and primary sensory cortex were frequently engaged during affective experiences driven by visual, auditory, olfactory, gustatory, and somatosensory inputs. A classification analysis demonstrated that the pattern of neural activity across a contrast map diagnosed the stimulus modality driving the affective experience. These findings suggest that affective experiences are constructed from activity that is distributed across limbic and paralimbic brain regions and also activity in sensory cortical regions. PMID:26696928

  14. Acoustical Characterization of the Columbia River Estuary

    NASA Astrophysics Data System (ADS)

    Reeder, D. B.

    2014-12-01

    Investigations of near-shore and in-shore environments have, rightly, focused on geological, thermodynamic and hydrodynamic parameters. A complementary acoustical characterization of the estuarine environment provides another layer of information to facilitate a more complete understanding of the physical environment. Relatively few acoustical studies have been carried out in rivers, estuaries or other energetic environments; nearly all acoustical work in such environments has been done at high acoustic frequencies—in the 10's and 100's of kHz. To this end, within the context of a larger hydrodynamic field experiment (RIVET II), a small acoustic field experiment was carried out in the Columbia River Estuary (CRE), the acoustic objective of which was to characterize the acoustic environment in the CRE in terms of ambient noise field statistics and acoustic propagation characteristics at low-to-mid-frequencies. Acoustically, the CRE salt wedge consists of two isospeed layers separated by a thin, three-dimensional high-gradient layer. Results demonstrate that (1) this stratification supports ducting of low-angle acoustic energy in the upper layer and the creation of an acoustic shadow zone in the lower layer; (2) the spatiotemporal dynamics of the salt wedge structure during the very energetic flood and ebb tides induce significant variability in the acoustic environment, as well as significant flow noise across the acoustic transducer; and (3) this flow noise correlates to current velocity and complicates acoustical observations at low frequencies.

  15. Understanding involvement in surgical orthopaedic randomized controlled trials: A qualitative study of patient and health professional views and experiences

    PubMed Central

    Horwood, Jeremy; Johnson, Emma; Gooberman-Hill, Rachael

    2016-01-01

    Background Factors influencing patients' motivations for enrolling in, and their experiences of, orthopaedic randomized controlled trials (RCTs) are not fully understood. Less is known about healthcare professionals' (HCP) experiences of RCT involvement. Aim This study investigates patients' and HCPs' views and experiences of RCT participation and delivery to inform the planning of future RCTs. Methods Total hip or knee replacement patients (n = 24) participating in the single-center double-blind APEX RCTs of an intra-operative anesthetic intervention and HCPs (n = 15) involved in trial delivery were interviewed. Data were audio-recorded, transcribed, anonymized and thematically analyzed. Results Although altruistic reasons for RCT participation were common, patients also weighed up demands of the RCT with the potential benefits of taking part, demonstrating the complex and conditional nature of trial participation. HCPs were interested in RCT involvement as a means of contributing towards advances in medical knowledge and also considered the costs and benefits of RCT involvement. Conclusion Patients and HCPs value involvement in RCTs that they see as relevant and of value, while imposing minimum burden. These findings have important implications for the design of methods to recruit patients to RCTs and for planning how an RCT might best interface with HCP clinical commitments. PMID:26772763

  16. Introducing DIASCoPE: Directly Integrated Acoustic System Combined with Pressure Experiments — Changing the Paradigm from Product to Process

    NASA Astrophysics Data System (ADS)

    Whitaker, M. L.; Baldwin, K. J.; Huebsch, W. B.; Tercé, N.; Bejina, F.; Bystricky, M.; Chen, H.; Vaughan, M. T.; Weidner, D. J.

    2014-12-01

    Understanding the properties and behaviors of materials and multi-phase aggregates under conditions of high pressure and temperature is vital to unraveling the mysteries that lie beneath the surface of the planet. Advances in in situexperimental techniques using synchrotron radiation at these extreme conditions have helped to provide answers to fundamental questions that were previously unattainable. Synchrotron-based ultrasonic interferometry measurements have proven to be especially important in determining acoustic velocities and thermoelastic properties of materials at high pressures and temperatures. However, due to relatively slow data collection times, it has been difficult to measure the effects of processes as they occur, and instead the measurement is made on the end product of these processes. DIASCoPE is an important step toward addressing this problem.Over the last three years, we have designed and developed an on-board ultrasonic acoustic velocity measurement system that cuts data collection time down by over an order of magnitude. We can now measure P- and S-wave travel times in samples at extreme conditions in less than one second. Moreover, the system has been fully integrated with the multi-anvil apparatus and the EPICS control system at beamline X17B2 of the National Synchrotron Light Source, allowing for greater ease of control andfull automation of experimental data collection. The DIASCoPE has completed the testing and commissioning phase, and the first data collected using this powerful new system will be presented here.DIASCoPE represents a major step forward in acoustic velocity collection time reduction that will finally allow us to begin to witness what effects various processes in the deep Earth may have on the physical properties of materials at extreme conditions as they occur. These new capabilities will allow us to change the focus of study from the product to the process itself and will lead to a greater understanding of the

  17. A Phenomenological Study of the Lived Experiences of Elementary Principals Involved in Dual-Career Relationships with Children

    ERIC Educational Resources Information Center

    Zeeck, Kirk A.

    2012-01-01

    This qualitative study examines the experiences of eight elementary principals from the Midwest who were involved in dual-career relationships with children under the age of 18. The primary data collection method was in-depth interviews. The data were coded and analyzed according to the research questions. The research resulted in three major…

  18. Musical Acoustics

    NASA Astrophysics Data System (ADS)

    Gough, Colin

    This chapter provides an introduction to the physical and psycho-acoustic principles underlying the production and perception of the sounds of musical instruments. The first section introduces generic aspects of musical acoustics and the perception of musical sounds, followed by separate sections on string, wind and percussion instruments.

  19. Digital Controller For Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Tarver, D. Kent

    1989-01-01

    Acoustic driver digitally controls sound fields along three axes. Allows computerized acoustic levitation and manipulation of small objects for such purposes as containerless processing and nuclear-fusion power experiments. Also used for controlling motion of vibration-testing tables in three dimensions.

  20. Acoustic Similarity and Dichotic Listening.

    ERIC Educational Resources Information Center

    Benson, Peter

    1978-01-01

    An experiment tests conjectures that right ear advantage (REA) has an auditory origin in competition or interference between acoustically similar stimuli and that feature-sharing effect (FSE) has its origin in assignment of features of phonetically similar stimuli. No effect on the REA for acoustic similarity, and a clear effect of acoustic…

  1. The Experiences and Involvement of Grandparents in Hearing Detection and Intervention

    ERIC Educational Resources Information Center

    McNee, Chelsea M.; Jackson, Carla W.

    2012-01-01

    The purpose of this study was to examine the involvement of grandparents during hearing detection and intervention. Data were collected and analyzed from survey responses of 50 parents and 35 grandparents of children of varying ages who have hearing loss. Parents described important types of support that grandparents provided including frequent…

  2. Family Involvement in Children's Mathematics Education Experiences: Voices of Immigrant Chinese American Students and Their Parents

    ERIC Educational Resources Information Center

    Liang, Senfeng

    2013-01-01

    This study examines ways in which Chinese immigrant families are involved in their children's mathematics education, particularly focusing on how different types of families utilize different forms of capital to support their children's mathematics education. The theoretical framework defines four types of Chinese immigrant families--working…

  3. Community and Parent Involvement in Early Childhood Development: The South African Experience.

    ERIC Educational Resources Information Center

    Atmore, Eric; And Others

    Noting that disadvantaged communities in South Africa can be empowered by involving parents and communities in the development of preschool education programs, this report presents the achievements of South Africa's Early Childhood Education and Care (educare) programs. Educare aims to develop the young child's potential to be a meaningful part of…

  4. The Vocational Goals and Career Development of Criminally Involved Youth: Experiences That Help and Hinder

    ERIC Educational Resources Information Center

    Bartlett, Jennifer; Domene, José F.

    2015-01-01

    Little is known about the career development of youth with a history of criminal activity and the factors that influence their career development. The ability to secure employment is important in predicting successful outcomes for this population, but unfortunately youth who have been involved in crime are likely to face a myriad of obstacles to…

  5. Multiscale analysis of waves reflected by granular media: Acoustic experiments on glass beads and effective medium theories

    NASA Astrophysics Data System (ADS)

    Le Gonidec, Yves; Gibert, Dominique

    2007-05-01

    The wavelet response is a multiscale method based on the continuous wavelet transform. We use it to characterize the acoustic reflectivity of a layer of glass beads with diameter d = 1 mm randomly arranged in water. The volumetric concentration is ϕ ≃ 63% of spherical inclusions. The wavelet response is measured over a large frequency range (100 kHz ≤ f ≤ 5 MHz) where five different acoustic regimes are identified on the basis of scattering phenomena. A strong decrease in the reflectivity occurs when the wavelength of the incident wave is twice the bead diameter, a situation where lateral scattering is dominant. The energy ratio of the ballistic and the coda parts of the wavelet response reveals a clear transition from a ballistic propagation regime to a diffusion regime where multiple scattering occurs. The experimental data are explained with an effective medium theory approach: the reflectivity data in the low-frequency domain of the spanned frequency range are correctly reproduced with quasi-static models. For higher frequencies, more sophisticated models accounting for multiple scattering must be used. The high-frequency part of the experimental reflectivity curve may be explained by strong multiple scattering at the top of the glass beads located at the surface of the layer and corresponds to the optical geometric limit.

  6. Diffusion with chemical reaction: An attempt to explain number density anomalies in experiments involving alkali vapor

    NASA Technical Reports Server (NTRS)

    Snow, W. L.

    1974-01-01

    The mutual diffusion of two reacting gases is examined which takes place in a bath of inert gas atoms. Solutions are obtained between concentric spheres, each sphere acting as a source for one of the reactants. The calculational model is used to illustrate severe number density gradients observed in absorption experiments with alkali vapor. Severe gradients result when sq root k/D R is approximately 5 where k, D, and R are respectively the second order rate constant, the multicomponent diffusion constant, and the geometrical dimension of the experiment.

  7. A Model for Engaging Students in a Research Experience Involving Variational Techniques, Mathematica, and Descent Methods.

    ERIC Educational Resources Information Center

    Mahavier, W. Ted

    2002-01-01

    Describes a two-semester numerical methods course that serves as a research experience for undergraduate students without requiring external funding or the modification of current curriculum. Uses an engineering problem to introduce students to constrained optimization via a variation of the traditional isoperimetric problem of finding the curve…

  8. Labor Force Experiences of a National Sample of Young Adult Men: The Role of Drug Involvement.

    ERIC Educational Resources Information Center

    Kandel, Denise B.; Davies, Mark

    1990-01-01

    Investigates the effects of the use of cigarettes, alcohol, marijuana, and cocaine on the following aspects of labor force experience: (1) earnings; (2) stability of employment; (3) gaps between employment spells; and (4) duration of unemployment. Illicit drug use was found to have an impact on all factors except earnings. (JS)

  9. Evaluation of experiments involving the study of plant orientation and growth under different gravitational conditions.

    PubMed

    Merkys, A J; Laurinavicius, R S; Svegzdiene, D V; Rakleviciene, D P; Jarosius, A V; Rupainiene, O J

    1989-01-01

    The manifestation of gravitropic reaction in plants has been considered from the phylogenetic point of view. A chart has been suggested according to which it is supposed that the first indications of the ability to identify the direction of the gravitational vector were inherent in the most ancient eukaryotes, which gave rise to green, brown, yellow-green, golden and diatomaceous algae as well as fungi. The experiments on the role of gravity in plant ontogenesis are being continued. The sum total of the data obtained in a number of experiments in space shows that under these conditions a structurally modified but normally functioning gravireceptive apparatus is formed. The data confirming the modification, under changed gravity, of the processes of integral and cellullar growth of the axial organs of seedlings as well as of the anatomo-morphological structure and developmental rates of plants during their prolonged growth in space are presented. It is assumed that this fact testifies to the presence of systems interacting with gravity during plant ontogenesis. At the same time the necessity for further experiments in order to differentiate an immediate biological effect of gravity from the ones conditioned by it indirectly due to the changes in the behavior of liquids and gases is pointed out. The methodological aspects of biological experiments in space as the main source of reliable information on the biological role of gravity are discussed. PMID:11537336

  10. Understanding Men's Prenatal Experience and the Father Involvement Connection: Assessing Baby Steps

    ERIC Educational Resources Information Center

    Marsiglio, William

    2008-01-01

    Cabrera, Fagan, and Farrie's research provides a useful springboard to encourage scholars to think broadly and productively about theoretical, substantive, methodological, and social intervention issues related to men's prenatal experiences, transitional life course events, and subsequent engagement with their young children. To their credit, the…

  11. Testing the Adventure Recreation Model: A Replication with Subjects Involved in a Required Outdoor Experience.

    ERIC Educational Resources Information Center

    Anderson, Lynn; Anderson, Dale; Young, Anderson

    In 1989, Ewert and Hollenhorst proposed the Adventure Recreation Model to describe participant characteristics, behaviors, and motivations with regard to adventure recreation activities. The model relates participant attributes (frequency of participation, skill and experience level, locus of control, and motivation factors) to activity/setting…

  12. Involving Children in Reflective Discussions about Their Perceived Self-Efficacy and Learning Experiences

    ERIC Educational Resources Information Center

    Määttä, Elina; Järvelä, Sanna

    2013-01-01

    Previous research indicates the importance of self-efficacy beliefs for young children's learning and achievement. However, the challenge has been to research young children's self-efficacy in authentic learning situations. Therefore, the aims of this study were to investigate young children's immediate experiences of confidence in…

  13. TEACHING PHYSICS: An experiment to demonstrate the principles and processes involved in medical Doppler ultrasound

    NASA Astrophysics Data System (ADS)

    Andrews, D. G. H.

    2000-09-01

    Doppler ultrasound is widely used in medicine for measuring blood velocity. This paper describes an experiment illustrating the principles of medical Doppler ultrasound. It is designed with A-level/undergraduate physics students in mind. Ultrasound is transmitted in air and reflected from a moving target. The return signal is processed using a series of modules, so that students can discover for themselves how each stage in the instrument works. They can also obtain a quantitative value of the speed of the target.

  14. Excitatory and inhibitory conversive experiences: neurobiological features involving positive and negative conversion symptoms.

    PubMed

    Río-Casanova, Lucía Del; González, Anabel; Páramo, Mario; Brenlla, Julio

    2016-01-01

    Previous reviews have focused on neurobiological and physiological mechanisms underlying conversion disorder, but they do not usually distinguish between negative and positive conversion symptoms. Some authors have proposed that different phenomena should underlie both situations and that diverse emotion regulation strategies (under- vs. overregulation of affect) should be related to different internal experiences (excitatory experiences with hyperarousal manifestations vs. inhibitory experiences coexisting with hypoarousal states, respectively). After a careful review of the literature, we conclude that there is not a unique theory comprising all findings. Nevertheless, we have also collected some replicated findings that should be salient. Patients manifesting positive conversion symptoms tended to present with limbic hyperfunction, not sufficiently counteracted by prefrontal control. This leads to underregulation of affect mechanisms, increased emotional reactivity and autonomic hyperarousal. The opposite pattern (with a prefrontal overfunction working as a cognitive brake over the limbic system) has been described during negative conversion manifestations. We also highlight the influence of fronto-limbic circuits over cortico-striato-thalamo-cortical circuits' regulation, whose horizontal and vertical synchronization has been at the spotlight of the genesis of conversion and dissociative disorders. PMID:26259230

  15. Robust acoustic wave manipulation of bubbly liquids

    NASA Astrophysics Data System (ADS)

    Gumerov, N. A.; Akhatov, I. S.; Ohl, C.-D.; Sametov, S. P.; Khazimullin, M. V.; Gonzalez-Avila, S. R.

    2016-03-01

    Experiments with water-air bubbly liquids when exposed to acoustic fields of frequency ˜100 kHz and intensity below the cavitation threshold demonstrate that bubbles ˜30 μm in diameter can be "pushed" away from acoustic sources by acoustic radiation independently from the direction of gravity. This manifests formation and propagation of acoustically induced transparency waves (waves of the bubble volume fraction). In fact, this is a collective effect of bubbles, which can be described by a mathematical model of bubble self-organization in acoustic fields that matches well with our experiments.

  16. Seamount acoustic scattering

    NASA Astrophysics Data System (ADS)

    Boehlert, George W.

    The cover of the March 1 issue of Eos showed a time series of acoustic scattering above Southeast Hancock Seamount (29°48‧N, 178°05‧E) on July 17-18, 1984. In a comment on that cover Martin Hovland (Eos, August 2, p. 760) argued that gas or “other far reaching causes” may be involved in the observed acoustic signals. He favors a hypothesis that acoustic scattering observed above a seeping pockmark in the North Sea is a combination of bubbles, stable microbubbles, and pelagic organisms and infers that this may be a more general phenomenon and indeed plays a role in the attraction of organisms to seamounts

  17. Room Acoustics

    NASA Astrophysics Data System (ADS)

    Kuttruff, Heinrich; Mommertz, Eckard

    The traditional task of room acoustics is to create or formulate conditions which ensure the best possible propagation of sound in a room from a sound source to a listener. Thus, objects of room acoustics are in particular assembly halls of all kinds, such as auditoria and lecture halls, conference rooms, theaters, concert halls or churches. Already at this point, it has to be pointed out that these conditions essentially depend on the question if speech or music should be transmitted; in the first case, the criterion for transmission quality is good speech intelligibility, in the other case, however, the success of room-acoustical efforts depends on other factors that cannot be quantified that easily, not least it also depends on the hearing habits of the listeners. In any case, absolutely "good acoustics" of a room do not exist.

  18. Acoustic Neuroma

    MedlinePlus

    ... slow growing tumor which arise primarily from the vestibular portion of the VIII cranial nerve and lie ... you have a "brain tumor" called acoustic neuroma (vestibular schwannoma). You think you are the only one ...

  19. Underwater Acoustics

    NASA Astrophysics Data System (ADS)

    Kuperman, William A.; Roux, Philippe

    It is well underwater established that sound waves, compared to electromagnetic waves, propagate long distances in the ocean. Hence, in the ocean as opposed to air or a vacuum, one uses sound navigation and ranging (SONAR) instead navigation and ranging (SONAR) of radar, acoustic communication instead of radio, and acoustic imaging and tomography instead of microwave or optical imaging or X-ray tomography. Underwater acoustics is the science of sound in water (most commonly in the ocean) and encompasses not only the study of sound propagation, but also the masking of sound signals by interfering phenomenon and signal processing for extracting these signals from interference. This chapter we will present the basics physics of ocean acoustics and then discuss applications.

  20. Ultrasonic and acoustic emission results from the Stripa heater experiments. Part I. Cross-hole investigation of a rock mass subjected to heating. Part II. Acoustic emission monitoring during cool-down of the Stripa heater experiment

    SciTech Connect

    Paulsson, B.N.P.; King, M.S.; Rachiele, R.

    1980-12-01

    A cross-hole high-frequency acoustic investigation of a granitic rock mass subjected to sustained heating is reported. Compressional and shear-wave velocity measurements along four different paths between four vertical boreholes were made prior to turning on the heater, during 398 days of heating, and after the heater was turned off. These measurements correlated well with the presence of fracture zones, in which the fractures were closed by thermal expansion of the rock upon heating. When the rock mass cooled, the velocity measurements indicated a greater intensity of fracturing than had existed before heating. Laboratory compressional and shear-wave velocity measurements were also made on intact rock specimens obtained from the site and subjected to axial stress. When used to interpret the increases in velocities measured in the field upon heating the rock mass, these measurements implied increases in horizontal normal stresses to between 30 and 40 MPa. Increases in these magnitudes agree with stress measurements made by the other techniques. The ratio of measured compressional to shear-wave velocity appears to provide a sensitive measure of the fraction of crack porosity containing water or gas.

  1. Structuring Student Involved NASA Flight Programs for High Quality Hardware Return While Maximizing the Student Learning Experience

    NASA Astrophysics Data System (ADS)

    Tate, G.; Reed, H.; Kohnert, R.; Lankton, M.; Chamberlain, P.; Ryan, S.; Steg, S.; Withnell, P.

    2005-12-01

    Organizational structure, practice, and management have an enormous affect on the success of student-lead and student-involved instrument missions. Through its involvements with the student projects SME, SNOE and SDC, LASP has developed organizational approaches that provide high-quality for-flight hardware that employs a mix of professionals and students. Keys to the success of these programs include the following tenets: 1) the professional involvement needs to be well defined at the onset of the program; 2) the organizational structure needs to be clearly defined; 3) student expectations and learning outcomes should be predetermined; and 4) the scope of the project needs to incorporate the time constraints of student availability so that outcomes allow students to experience project success (or project milestones) prior to graduation.

  2. Opto-acoustic diagnostics of the thermal action of high-intensity focused ultrasound on biological tissues: the possibility of its applications and model experiments

    SciTech Connect

    Khokhlova, Tanya D; Pelivanov, Ivan M; Solomatin, Vladimir S; Karabutov, Aleksander A; Sapozhnikov, Oleg A

    2006-12-31

    The possibility of using the opto-acoustic (OA) method for monitoring high-intensity ultrasonic therapy is studied. The optical properties of raw and boiled liver samples used as the undamaged model tissue and tissue destroyed by ultrasound, respectively, are measured. Experiments are performed with samples consisting of several alternating layers of raw and boiled liver of different thickness. The position and transverse size of the thermal lesion were determined from the temporal shape of the OA signals. The results of measurements are compared with the real size and position of the thermal lesion determined from the subsequent cuts of the sample. It is shown that the OA method permits the diagnostics of variations in biological tissues upon ultrasonic therapy. (special issue devoted to multiple radiation scattering in random media)

  3. Involving the public in decision-making at federal facilities: The Department of Energy experience

    SciTech Connect

    Gesalman, C.M.

    1996-12-31

    The Department of Energy is involved in cleanup of a wide variety of sites used in the development and production of nuclear weapons. Substantial and increasing efforts have been made to involve the public in the planning and implementation of the cleanup projects. Early in the program, public participation was mainly an information transfer effort. More recently, innovative techniques have been used to increase public understanding of the tradeoffs required in making cleanup decisions (e.g., more stringent cleanup standards lead to higher costs). Sites now realize that relationships are key and are working to develop them. Advisory boards have been established at several sites. The methods of forming the boards have varied from site to site, as have the size of the group and the issues addressed. The effectiveness of the boards in their goal of improving public participation at the sites will be evaluated in the next fiscal year. DOE has sought public input on an increasing number of issues, such as future use of its facilities, environmental justice concerns, and budget development. Assumptions about future use of sites are crucial to setting realistic cleanup standards and controlling costs. Decisions made in the early phases of the budget process are now based in part on stakeholder input regarding priorities; for example, stakeholder concerns about and support for emphasizing plutonium cleanup at Rocky Flats have led to changes in priorities between the materials stabilization and environmental restoration programs. Environmental justice has become an increasing issue; sites must ensure that public participation programs effectively reach minority and low-income populations.

  4. Strong acoustic wave action

    NASA Astrophysics Data System (ADS)

    Gokhberg, M. B.

    1983-07-01

    Experiments devoted to acoustic action on the atmosphere-magnetosphere-ionosphere system using ground based strong explosions are reviewed. The propagation of acoustic waves was observed by ground observations over 2000 km in horizontal direction and to an altitude of 200 km. Magnetic variations up to 100 nT were detected by ARIEL-3 satellite near the epicenter of the explosion connected with the formation of strong field aligned currents in the magnetosphere. The enhancement of VLF emission at 800 km altitude is observed.

  5. NSTA-NASA Shuttle Student Involvement Project. Experiment Results: Insect Flight Observation at Zero Gravity

    NASA Technical Reports Server (NTRS)

    Nelson, T. E.; Peterson, J. R.

    1982-01-01

    The flight responses of common houseflies, velvetbean caterpillar moths, and worker honeybees were observed and filmed for a period of about 25 minutes in a zero-g environment during the third flight of the Space Shuttle Vehicle (flight number STS-3; March 22-30, 1982). Twelve fly puparia, 24 adult moths, 24 moth pupae, and 14 adult bees were loaded into an insect flight box, which was then stowed aboard the Shuttle Orbiter, the night before the STS-3 launch at NASA's Kennedy Space Center (KSC). The main purpose of the experiment was to observe and compare the flight responses of the three species of insects, which have somewhat different flight control mechanisms, under zero-g conditions.

  6. Definition Study for Space Shuttle Experiments Involving Large, Steerable Millimeter-Wave Antenna Arrays

    NASA Technical Reports Server (NTRS)

    Levis, C. A.

    1976-01-01

    The potential uses and techniques for the shuttle spacelab Millimeter Wave Large Aperture Antenna Experiment (MWLAE) are documented. Potential uses are identified: applications to radio astronomy, the sensing of atmospheric turbulence by its effect on water vapor line emissions, and the monitoring of oil spills by multifrequency radiometry. IF combining is preferable to RF combining with respect to signal to noise ratio for communications receiving antennas of the size proposed for MWLAE. A design approach using arrays of subapertures is proposed to reduce the number of phase shifters and mixers for uses which require a filled aperture. Correlation radiometry and a scheme utilizing synchronous Dicke switches and IF combining are proposed as potential solutions.

  7. Dose reconstruction for weapons experiments involving 140La at Los Alamos National Laboratory, 1944-1962.

    PubMed

    Kraig, D H

    1997-10-01

    A series of 254 weapons design experiments was conducted by Los Alamos National Laboratory from 1944 through 1962 and resulted in the dispersal of approximately 11 PBq (300 kCi) of radioactive 140La. All shots occurred at Point Able in Bayo Canyon, east of the Los Alamos townsite. Public interest and the Government Accounting Office probe precipitated a dose reconstruction to assess potential exposures to members of the public. The information available for each shot included explosive charge size, date and time of explosion, and shot activity. Detailed meteorological data were not available for the majority of the shots, requiring the development of statistically representative meteorological data. A wind rose was developed specific to the afternoon-evening time of the shots, and the wind frequency in each sector was used to determine the fraction of activity dispersed towards each hypothetical receptor. HOTSPOT 7, a Gaussian plume-based dispersion model, was used to determine the average dose per sector per unit of shot activity. The dose from penetrating radiation from ground-deposited 140La was greater by several orders of magnitude than the dose from inhalation and immersion. The highest doses to a permanent resident probably occurred in the easternmost part of the Los Alamos townsite. The highest annual dose occurred in 1955 and was approximately 0.23 mSv. Assuming an individual had been at the location of maximum potential exposure in the Los Alamos townsite continuously throughout the experiments, the total dose from the 18-y series would have been approximately 1.4 mSv with an average dose of approximately 0.09 mSv y(-1). Doses at nearby Totavi trailer park, San Ildefonso Pueblo, and Santa Clara Pueblo were approximately 75%, 40%, and 15%, respectively, of those at Los Alamos. Visitors to nearby public areas received negligible doses. PMID:9314221

  8. Accelerators for critical experiments involving single-particle upset in solid-state microcircuits

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.

    1985-01-01

    Charged-particle interactions in microelectronic circuit chips (integrated circuits) present a particularly insidious problem for solid-state electronic systems due to the generation of soft errors or single-particle event upset (SEU) by either cosmic rays or other radiation sources. Particle accelerators are used to provide both light and heavy ions in order to assess the propensity of integrated circuit chips for SEU. Critical aspects of this assessment involve the ability to analytically model SEU for the prediction of error rates in known radiation environments. In order to accurately model SEU, the measurement and prediction of energy deposition in the form of an electron-hole plasma generated along an ion track is of paramount importance. This requires the use of accelerators which allow for ease in both energy control (change of energy) and change of ion species. This and other aspects of ion-beam control and diagnostics (e.g., uniformity and flux) are of critical concern for the experimental verification of theoretical SEU models.

  9. The experiences of emergency department use by street-involved youth: Perspectives of health care and community service providers.

    PubMed

    Nicholas, David B; Newton, Amanda S; Kilmer, Christopher; Calhoun, Avery; deJong-Berg, Margaret A; Dong, Kathryn; Hamilton, Faye; McLaughlin, Anne Marie; Shankar, Janki; Smyth, Peter

    2016-08-01

    Street-involved (SI) youth represent a significant proportion of urban homeless populations. While previous research has identified SI youth as substantial users of emergency department (ED) services and has examined their experiences of ED care, little is known about the experiences and perceptions of the service providers who assist these youth with health care related issues. Using grounded theory, individual interviews and focus groups were conducted with 20 community agency staff serving SI youth, 17 health service providers, two hospital administrators, and two hospital security personnel regarding their experiences in providing or facilitating ED care for SI youth. Results identify differences in expectations between SI youth and hospital staff, along with service issues and gaps, including relational barriers and resource constraints. Implications for practice and policy development are offered. PMID:27351791

  10. Quantitative measures of air-gun pulses recorded on sperm whales (Physeter macrocephalus) using acoustic tags during controlled exposure experiments.

    PubMed

    Madsen, P T; Johnson, M; Miller, P J O; Aguilar Soto, N; Lynch, J; Tyack, P

    2006-10-01

    The widespread use of powerful, low-frequency air-gun pulses for seismic seabed exploration has raised concern about their potential negative effects on marine wildlife. Here, we quantify the sound exposure levels recorded on acoustic tags attached to eight sperm whales at ranges between 1.4 and 12.6 km from controlled air-gun array sources operated in the Gulf of Mexico. Due to multipath propagation, the animals were exposed to multiple sound pulses during each firing of the array with received levels of analyzed pulses falling between 131-167 dB re. 1 microPa (pp) [111-147 dB re. 1 microPa (rms) and 100-135 dB re. 1 microPa2 s] after compensation for hearing sensitivity using the M-weighting. Received levels varied widely with range and depth of the exposed animal precluding reliable estimation of exposure zones based on simple geometric spreading laws. When whales were close to the surface, the first arrivals of air-gun pulses contained most energy between 0.3 and 3 kHz, a frequency range well beyond the normal frequencies of interest in seismic exploration. Therefore air-gun arrays can generate significant sound energy at frequencies many octaves higher than the frequencies of interest for seismic exploration, which increases concern of the potential impact on odontocetes with poor low frequency hearing. PMID:17069331

  11. 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

  12. 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

  13. Twenty years' experience in the treatment of acoustic neuromas with fractionated radiotherapy: A review of 45 cases

    SciTech Connect

    Maire, Jean-Philippe . E-mail: jean-philippe.maire@chu-bordeaux.fr; Huchet, Aymeri; Milbeo, Yann; Darrouzet, Vincent; Causse, Nicole; Celerier, Denis; Liguoro, Dominique; Bebear, Jean-Pierre

    2006-09-01

    Purpose: To evaluate very long-term results of fractionated radiotherapy (FRT) of acoustic neuromas (AN). Methods and Materials: From January 1986 to January 2004, FRT was performed in 45 consecutive patients (46 AN). Indications were as follows: poor general condition contraindicating surgery, hearing preservation in bilateral neuromas, partial resection, nonsurgical recurrence. A 3-field to 5-field technique with static beams was used. A mean total dose of 51 Gy was given (1.80 Gy/fraction). The median tumor diameter was 31 mm (range, 11-55 mm). The median follow-up from FRT was 80 months (range, 4-227 months). Results: The particularity of our series consists of a very long-term follow-up of FRT given to selected patients. Nineteen patients died, two with progressive disease, and 17 from non-AN causes. A serviceable level of hearing was preserved in 7/9 hearing patients. No patient had facial or trigeminal neuropathy. Tumor shrinkage was observed in 27 (59%) and stable disease in 16 (35%). Tumor progression occurred in three patients, 12 to 15 months after FRT. Two additional tumors recurred after shrinkage 20 and 216 months after treatment and were operated on. Actuarial local tumor control rates at 5 and 15 years were 86%. For the patient who had a tumor recurrence at 216 months, histologic examination documented transformation to a low-grade malignant peripheral nerve sheath tumor. Conclusion: Very long-term efficacy of FRT is well documented in this series. However, our results suggest that malignant transformation can occur many years after FRT so we advocate caution when using this treatment for young patients.

  14. Ethical review of regulatory toxicology guidelines involving experiments on animals: the example of endocrine disrupters.

    PubMed

    Purchase, I F

    1999-12-01

    The safety assessment of new chemicals (including medicines, pesticides, food additives, and industrial chemicals) relies on the results of animal experiments. Because the safety of those exposed to these products and the welfare of the experimental animals used are considered critically important, both testing requirements and the welfare of experimental animals are controlled by law. In the U.K., projects that propose to use animals for experimental purposes, including for the testing of chemicals, have been controlled by law for over a century, with the most recent legislation (Animals [Scientific Procedures] Act of 1986) requiring a cost/benefit assessment before it may proceed. New regulations introduced in 1998 will require an ethical review process for all projects from April 1999. Such ethical review will have to take account of the toxicity testing methods and schemes that are required by the legislation aimed at protecting human health. Neither national nor international proposals for toxicity testing methods and schemes are generally subjected to ethical review from the point of protecting animal welfare. The international nature of the chemical and pharmaceutical industry means that testing requirements from one of the major national regulatory agencies (USA, EU, or Japan) or the international organizations (Organization for Economic Co-operation and Development [OECD]or the International Conference on Harmonization [ICH]) have an impact on the testing carried out by industrial organizations in all countries. The recent proposals for screening and testing chemicals to identify endocrine disrupters (ED) from the Endocrine Disrupter Screening and Testing Advisory Committee (EDSTAC) of the U.S. Environmental Protection Agency (EPA) are used as an example of the interaction between regulatory proposals and animal welfare issues. The current proposals are the most extravagant in the use of animals. Between 0.6 and 1.2 million animals would be required for

  15. Endoscopic ultrasound-guided fine-needle aspiration diagnosis of secondary tumors involving the pancreas: An institution's experience

    PubMed Central

    Alomari, Almed K.; Ustun, Berrin; Aslanian, Harry R.; Ge, Xinquan; Chhieng, David; Cai, Guoping

    2016-01-01

    Background: Pancreatic masses may seldom represent a metastasis or secondary involvement by lymphoproliferative disorders. Recognition of this uncommon occurrence may help render an accurate diagnosis and avoid diagnostic pitfalls during endoscopic ultrasound-guided fine needle aspiration (EUS-FNA). In this study, we review our experience in diagnosing secondary tumors involving the pancreas. Materials and Methods: The electronic database of cytopathology archives was searched for cases of secondary tumors involving the pancreas at our institution and a total of 31 cases were identified. The corresponding clinical presentations, imaging study findings, cytological diagnoses, the results of ancillary studies, and surgical follow-up, if available, were reviewed. Results: Nineteen of the patients were male and 12 female, with a mean age of 66 years. Twenty-three patients (74%) had a prior history of malignancy, with the latency ranging from 6 months to 19 years. The secondary tumors involving the pancreas included metastatic carcinoma (24 cases), metastatic sarcoma (3 cases), diffuse large B-cell lymphoma (2 cases), and plasma cell neoplasm (2 cases). The most common metastatic tumors were renal cell carcinoma (8 cases) and lung carcinoma (7 cases). Correct diagnoses were rendered in 29 cases (94%). The remaining two cases were misclassified as primary pancreatic carcinoma. In both cases, the patients had no known history of malignancy, and no ancillary studies were performed. Conclusions: Secondary tumors involving the pancreas can be accurately diagnosed by EUS-FNA. Recognizing uncommon cytomorphologic features, knowing prior history of malignancy, and performing ancillary studies are the keys to improve diagnostic performance and avoid diagnostic pitfalls. PMID:26955395

  16. Reconstruction of the blood flow pattern by tomography of the acoustic nonlinearity parameter: Computer simulation and physical experiment

    NASA Astrophysics Data System (ADS)

    Burov, V. A.; Evtukhov, S. N.; Rumyantseva, O. D.

    2008-09-01

    A method is proposed for reconstructing the distribution of the total blood flow velocity vector from the data obtained within the nonlinear parameter tomography scheme. The method calculates the Doppler shift of the combination frequency with the use of the spectral analysis of the combination signal and the moving target selection procedure. Results of numerical simulations are presented, and possibilities of practical application of the method are discussed. A physical experiment is carried out. The results of this experiment are found to be in good agreement with the theory and the numerical model.

  17. Attitudes toward hiring applicants with mental illness and criminal justice involvement: the impact of education and experience.

    PubMed

    Batastini, Ashley B; Bolanos, Angelea D; Morgan, Robert D

    2014-01-01

    Individuals with mental health diagnoses, as well as those involved in the criminal justice system, experience a number of barriers in the recovery and reintegration progress, including access to stable, prosocial employment opportunities. Employment for these populations is important for establishing financial security, reducing unstructured leisure time, increasing self-worth, and improving interpersonal skills. However, research has demonstrated that individuals with psychiatric and/or criminal backgrounds may experience stigmatizing attitudes from employers that impede their ability to find adequate work. This study aimed to evaluate stigmatizing beliefs toward hypothetical applicants who indicated a mental health history, a criminal history, or both, as well as the effectiveness of psychoeducation in reducing stigma. Participants consisted of 465 individuals recruited from a large university who completed a series of online questions about a given applicant. Results of this study varied somewhat across measures of employability, but were largely consistent with extant research suggesting that mental illness and criminal justice involvement serve as deterrents when making hiring decisions. Overall, psychoeducation appeared to reduce stigma for hiring decisions when the applicant presented with a criminal history. Unfortunately, similar findings were not revealed when applicants presented with a psychiatric or a psychiatric and criminal history. Implications and limitations of these findings are presented, along with suggestions for future research. PMID:24629567

  18. Preliminary study of the effect of the turbulent flow field around complex surfaces on their acoustic characteristics

    NASA Technical Reports Server (NTRS)

    Olsen, W. A.; Boldman, D.

    1978-01-01

    Fairly extensive measurements have been conducted of the turbulent flow around various surfaces as a basis for a study of the acoustic characteristics involved. In the experiments the flow from a nozzle was directed upon various two-dimensional surface configurations such as the three-flap model. A turbulent flow field description is given and an estimate of the acoustic characteristics is provided. The developed equations are based upon fundamental theories for simple configurations having simple flows. Qualitative estimates are obtained regarding the radiation pattern and the velocity power law. The effect of geometry and turbulent flow distribution on the acoustic emission from simple configurations are discussed.

  19. The Simplest Demonstration on Acoustic Beats

    ERIC Educational Resources Information Center

    Ganci, Alessio; Ganci, Salvatore

    2015-01-01

    The classical demonstration experiment on acoustic beats using two signal generators and a dual trace oscilloscope is an important ingredient in teaching the subject. This short laboratory note aims to point out what may be the simplest demonstrative experiment on acoustic beats to carry out in a classroom without employing any lab apparatus.

  20. 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.

  1. Theory on acoustic sources

    NASA Technical Reports Server (NTRS)

    Wright, S. E.

    1978-01-01

    A theory is described for the radiation emission emission from acoustic multipole sources. The sources can be stationary or moving at speeds including supersonic and experience stationary or moving disturbances. The effect of finite source distributions and disturbances is investigated as well as the manner in which they interact. Distinction is made between source distributions that responsed as a function of time and those that respond as a function of space.

  2. Acoustic studies for alpha background rejection in dark matter bubble chamber detectors

    SciTech Connect

    Bou-Cabo, M.; Felis, I.; Ardid, M.; Collaboration: COUPP Collaboration

    2013-08-08

    COUPP (Chicagoland Observatory for Underground Particle Physics) is an experiment with bubble chambers able to detect dark matter directly either with Spin-Dependent or with Spin-Independent interactions. The target material is a superheated liquid (usually CF3I) that can be bubble nucleated due to nuclear recoils produced by elastic collisions of dark matter particles. The bubble growth inside the chamber is accompanied with an acoustic signature. The acoustic technique has been successfully used to have a good alpha discrimination (about 99%). In this paper, we present different studies and results related with the characterization of the acoustic properties of the detector and the different phenomena involved in the acoustic measurements of the bubble growth, such as sound generation, sound transmission and optimization of piezoelectric transducers.

  3. 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.

  4. 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.

  5. Beta-induced Alfvén-acoustic eigenmodes in National Spherical Torus Experiment and DIII-D driven by beam ionsa)

    NASA Astrophysics Data System (ADS)

    Gorelenkov, N. N.; Van Zeeland, M. A.; Berk, H. L.; Crocker, N. A.; Darrow, D.; Fredrickson, E.; Fu, G.-Y.; Heidbrink, W. W.; Menard, J.; Nazikian, R.

    2009-05-01

    Kinetic theory and experimental observations of a special class of energetic particle driven instabilities called here beta-induced Alfvén-acoustic eigenmodes (BAAEs) are reported confirming, previous results [N. N. Gorelenkov et al., Plasma Phys. Controlled Fusion 49, B371 (2007)]. The kinetic theory is based on the ballooning dispersion relation where the drift frequency effects are retained. BAAE gaps are recovered in kinetic theory. It is shown that the observed certain low-frequency instabilities on DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] and National Spherical Torus Experiment [M. Ono, S. M. Kaye, Y.-K. M. Peng et al., Nucl. Fusion 40, 557 (2000)] are consistent with their identification as BAAEs. BAAEs deteriorate the fast ion confinement in DIII-D and can have a similar effect in next-step fusion plasmas, especially if excited together with multiple global toroidicity-induced shear Alfvén eigenmode instabilities. BAAEs can also be used to diagnose safety factor profiles, a technique known as magnetohydrodynamic spectroscopy.

  6. Low-frequency target strength and abundance of shoaling Atlantic herring (Clupea harengus) in the Gulf of Maine during the Ocean Acoustic Waveguide Remote Sensing 2006 Experiment.

    PubMed

    Gong, Zheng; Andrews, Mark; Jagannathan, Srinivasan; Patel, Ruben; Jech, J Michael; Makris, Nicholas C; Ratilal, Purnima

    2010-01-01

    The low-frequency target strength of shoaling Atlantic herring (Clupea harengus) in the Gulf of Maine during Autumn 2006 spawning season is estimated from experimental data acquired simultaneously at multiple frequencies in the 300-1200 Hz range using (1) a low-frequency ocean acoustic waveguide remote sensing (OAWRS) system, (2) areal population density calibration with several conventional fish finding sonar (CFFS) systems, and (3) low-frequency transmission loss measurements. The OAWRS system's instantaneous imaging diameter of 100 km and regular updating enabled unaliased monitoring of fish populations over ecosystem scales including shoals of Atlantic herring containing hundreds of millions of individuals, as confirmed by concurrent trawl and CFFS sampling. High spatial-temporal coregistration was found between herring shoals imaged by OAWRS and concurrent CFFS line-transects, which also provided fish depth distributions. The mean scattering cross-section of an individual shoaling herring is found to consistently exhibit a strong, roughly 20 dB/octave roll-off with decreasing frequency in the range of the OAWRS survey over all days of the roughly 2-week experiment, consistent with the steep roll-offs expected for sub-resonance scattering from fish with air-filled swimbladders. PMID:20058955

  7. Structural-acoustic model of a rectangular plate-cavity system with an attached distributed mass and internal sound source: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Pirnat, Miha; Čepon, Gregor; Boltežar, Miha

    2014-03-01

    In this paper three approaches are combined to develop a structural-acoustic model of a rectangular plate-cavity system with an attached distributed mass and internal sound source. The first approach results from a recently presented analysis based on the Rayleigh-Ritz method and is used to circumvent the difficulties in obtaining the natural frequencies and mode shapes of a plate with an attached, distributed mass. Furthermore, different plate boundary conditions can be accommodated. The resulting mode shapes are defined as continuous functions; this is advantageous as they can be directly used in the second approach, i.e., the classic modal-interaction approach in order to obtain the coupled equations of the system. Finally, in the third approach a group of point sources emitting a pressure pulse in the time domain is used to model an internal sound source. For the validation of the developed model an experiment was conducted in two configurations using a simply supported aluminium plate and a clamped plate coupled with a plexiglas box containing a loudspeaker. Good agreement was found between the analytical and experimental data.

  8. Irregular reflection of weak acoustic shock pulses on rigid boundaries : Schlieren experiments and direct numerical simulation based on a Navier-Stokes solver

    NASA Astrophysics Data System (ADS)

    Desjouy, Cyril; Ollivier, Sébastien; Marsden, Olivier; Karzova, Maria; Blanc-Benon, Philippe

    2016-02-01

    The local interactions occurring between incident and reflected shock waves in the vicinity of rigid surfaces are investigated. Both regular and irregular — also called von Neumann — regimes of reflection are studied, via experimental and numerical simulations. Shock waves are produced experimentally with a 20 kV electrical spark source which allows the generation of spherically diverging acoustic shocks. The behaviour of the resulting weak acoustic shocks near rigid boundaries is visualized with a Schlieren optical technique which allows the spatial structure of the shocks to be studied. In particular, the evolution of the Mach stem forming above a flat surface is examined, and its height is observed to be directly linked to the angle of incidence and the pressure amplitude of the incident shock. The propagation of an acoustic shock between two parallel rigid boundaries is also studied. It is shown that the strong interactions between the Mach stems emerging from the two boundaries can lead to a drastic modification of the morphology of the acoustic field in the waveguide. Experimental results are compared to numerical results obtained from high-order finite-difference based simulations of the 2D Navier-Stokes equations. The good agreement between the experimental distribution of the acoustic field and numerical results suggests that numerical simulations are promising as a predictive tool to study nonlinear acoustic propagation of acoustic waves in complex geometrical configurations with rigid boundaries.

  9. 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

  10. Turbofan Acoustic Propagation and Radiation

    NASA Technical Reports Server (NTRS)

    Eversman, Walter

    2000-01-01

    This document describes progress in the development of finite element codes for the prediction of near and far field acoustic radiation from the inlet and aft fan ducts of turbofan engines. The report consists of nine papers which have appeared in archival journals and conference proceedings, or are presently in review for publication. Topics included are: 1. Aft Fan Duct Acoustic Radiation; 2. Mapped Infinite Wave Envelope Elements for Acoustic Radiation in a Uniformly Moving Medium; 3. A Reflection Free Boundary Condition for Propagation in Uniform Flow Using Mapped Infinite Wave Envelope Elements; 4. A Numerical Comparison Between Multiple-Scales and FEM Solution for Sound Propagation in Lined Flow Ducts; 5. Acoustic Propagation at High Frequencies in Ducts; 6. The Boundary Condition at an Impedance Wall in a Nonuniform Duct with Potential Flow; 7. A Reverse Flow Theorem and Acoustic Reciprocity in Compressible Potential Flows; 8. Reciprocity and Acoustics Power in One Dimensional Compressible Potential Flows; and 9. Numerical Experiments on Acoustic Reciprocity in Compressible Potential Flows.

  11. Controlling sound with acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    Cummer, Steven A.; Christensen, Johan; Alù, Andrea

    2016-03-01

    Acoustic metamaterials can manipulate and control sound waves in ways that are not possible in conventional materials. Metamaterials with zero, or even negative, refractive index for sound offer new possibilities for acoustic imaging and for the control of sound at subwavelength scales. The combination of transformation acoustics theory and highly anisotropic acoustic metamaterials enables precise control over the deformation of sound fields, which can be used, for example, to hide or cloak objects from incident acoustic energy. Active acoustic metamaterials use external control to create effective material properties that are not possible with passive structures and have led to the development of dynamically reconfigurable, loss-compensating and parity-time-symmetric materials for sound manipulation. Challenges remain, including the development of efficient techniques for fabricating large-scale metamaterial structures and converting laboratory experiments into useful devices. In this Review, we outline the designs and properties of materials with unusual acoustic parameters (for example, negative refractive index), discuss examples of extreme manipulation of sound and, finally, provide an overview of future directions in the field.

  12. Acoustic fault injection tool (AFIT)

    NASA Astrophysics Data System (ADS)

    Schoess, Jeffrey N.

    1999-05-01

    On September 18, 1997, Honeywell Technology Center (HTC) successfully completed a three-week flight test of its rotor acoustic monitoring system (RAMS) at Patuxent River Flight Test Center. This flight test was the culmination of an ambitious 38-month proof-of-concept effort directed at demonstrating the feasibility of detecting crack propagation in helicopter rotor components. The program was funded as part of the U.S. Navy's Air Vehicle Diagnostic Systems (AVDS) program. Reductions in Navy maintenance budgets and available personnel have dictated the need to transition from time-based to 'condition-based' maintenance. Achieving this will require new enabling diagnostic technologies. The application of acoustic emission for the early detection of helicopter rotor head dynamic component faults has proven the feasibility of the technology. The flight-test results demonstrated that stress-wave acoustic emission technology can detect signals equivalent to small fatigue cracks in rotor head components and can do so across the rotating articulated rotor head joints and in the presence of other background acoustic noise generated during flight operation. During the RAMS flight test, 12 test flights were flown from which 25 Gbyte of digital acoustic data and about 15 hours of analog flight data recorder (FDR) data were collected from the eight on-rotor acoustic sensors. The focus of this paper is to describe the CH-46 flight-test configuration and present design details about a new innovative machinery diagnostic technology called acoustic fault injection. This technology involves the injection of acoustic sound into machinery to assess health and characterize operational status. The paper will also address the development of the Acoustic Fault Injection Tool (AFIT), which was successfully demonstrated during the CH-46 flight tests.

  13. Three-dimensional manipulation of single cells using surface acoustic waves

    PubMed Central

    Guo, Feng; Mao, Zhangming; Chen, Yuchao; Xie, Zhiwei; Lata, James P.; Li, Peng; Ren, Liqiang; Liu, Jiayang; Yang, Jian; Dao, Ming; Suresh, Subra; Huang, Tony Jun

    2016-01-01

    The ability of surface acoustic waves to trap and manipulate micrometer-scale particles and biological cells has led to many applications involvingacoustic tweezers” in biology, chemistry, engineering, and medicine. Here, we present 3D acoustic tweezers, which use surface acoustic waves to create 3D trapping nodes for the capture and manipulation of microparticles and cells along three mutually orthogonal axes. In this method, we use standing-wave phase shifts to move particles or cells in-plane, whereas the amplitude of acoustic vibrations is used to control particle motion along an orthogonal plane. We demonstrate, through controlled experiments guided by simulations, how acoustic vibrations result in micromanipulations in a microfluidic chamber by invoking physical principles that underlie the formation and regulation of complex, volumetric trapping nodes of particles and biological cells. We further show how 3D acoustic tweezers can be used to pick up, translate, and print single cells and cell assemblies to create 2D and 3D structures in a precise, noninvasive, label-free, and contact-free manner. PMID:26811444

  14. Three-dimensional manipulation of single cells using surface acoustic waves.

    PubMed

    Guo, Feng; Mao, Zhangming; Chen, Yuchao; Xie, Zhiwei; Lata, James P; Li, Peng; Ren, Liqiang; Liu, Jiayang; Yang, Jian; Dao, Ming; Suresh, Subra; Huang, Tony Jun

    2016-02-01

    The ability of surface acoustic waves to trap and manipulate micrometer-scale particles and biological cells has led to many applications involving "acoustic tweezers" in biology, chemistry, engineering, and medicine. Here, we present 3D acoustic tweezers, which use surface acoustic waves to create 3D trapping nodes for the capture and manipulation of microparticles and cells along three mutually orthogonal axes. In this method, we use standing-wave phase shifts to move particles or cells in-plane, whereas the amplitude of acoustic vibrations is used to control particle motion along an orthogonal plane. We demonstrate, through controlled experiments guided by simulations, how acoustic vibrations result in micromanipulations in a microfluidic chamber by invoking physical principles that underlie the formation and regulation of complex, volumetric trapping nodes of particles and biological cells. We further show how 3D acoustic tweezers can be used to pick up, translate, and print single cells and cell assemblies to create 2D and 3D structures in a precise, noninvasive, label-free, and contact-free manner. PMID:26811444

  15. 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.

  16. 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.}

  17. West Texas array experiment: Noise and source characterization of short-range infrasound and acoustic signals, along with lab and field evaluation of Intermountain Laboratories infrasound microphones

    NASA Astrophysics Data System (ADS)

    Fisher, Aileen

    The term infrasound describes atmospheric sound waves with frequencies below 20 Hz, while acoustics are classified within the audible range of 20 Hz to 20 kHz. Infrasound and acoustic monitoring in the scientific community is hampered by low signal-to-noise ratios and a limited number of studies on regional and short-range noise and source characterization. The JASON Report (2005) suggests the infrasound community focus on more broad-frequency, observational studies within a tactical distance of 10 km. In keeping with that recommendation, this paper presents a study of regional and short-range atmospheric acoustic and infrasonic noise characterization, at a desert site in West Texas, covering a broad frequency range of 0.2 to 100 Hz. To spatially sample the band, a large number of infrasound gauges was needed. A laboratory instrument analysis is presented of the set of low-cost infrasound sensors used in this study, manufactured by Inter-Mountain Laboratories (IML). Analysis includes spectra, transfer functions and coherences to assess the stability and range of the gauges, and complements additional instrument testing by Sandia National Laboratories. The IMLs documented here have been found reliably coherent from 0.1 to 7 Hz without instrument correction. Corrections were built using corresponding time series from the commercially available and more expensive Chaparral infrasound gauge, so that the corrected IML outputs were able to closely mimic the Chaparral output. Arrays of gauges are needed for atmospheric sound signal processing. Our West Texas experiment consisted of a 1.5 km aperture, 23-gauge infrasound/acoustic array of IMLs, with a compact, 12 m diameter grid-array of rented IMLs at the center. To optimize signal recording, signal-to-noise ratio needs to be quantified with respect to both frequency band and coherence length. The higher-frequency grid array consisted of 25 microphones arranged in a five by five pattern with 3 meter spacing, without

  18. Sonification of acoustic emission data

    NASA Astrophysics Data System (ADS)

    Raith, Manuel; Große, Christian

    2014-05-01

    While loading different specimens, acoustic emissions appear due to micro crack formation or friction of already existing crack edges. These acoustic emissions can be recorded using suitable ultrasonic transducers and transient recorders. The analysis of acoustic emissions can be used to investigate the mechanical behavior of different specimens under load. Our working group has undertaken several experiments, monitored with acoustic emission techniques. Different materials such as natural stone, concrete, wood, steel, carbon composites and bone were investigated. Also the experimental setup has been varied. Fire-spalling experiments on ultrahigh performance concrete and pullout experiments on bonded anchors have been carried out. Furthermore uniaxial compression tests on natural stone and animal bone had been conducted. The analysis tools include not only the counting of events but the analysis of full waveforms. Powerful localization algorithms and automatic onset picking techniques (based on Akaikes Information Criterion) were established to handle the huge amount of data. Up to several thousand events were recorded during experiments of a few minutes. More sophisticated techniques like moment tensor inversion have been established on this relatively small scale as well. Problems are related to the amount of data but also to signal-to-noise quality, boundary conditions (reflections) sensor characteristics and unknown and changing Greens functions of the media. Some of the acoustic emissions recorded during these experiments had been transferred into audio range. The transformation into the audio range was done using Matlab. It is the aim of the sonification to establish a tool that is on one hand able to help controlling the experiment in-situ and probably adjust the load parameters according to the number and intensity of the acoustic emissions. On the other hand sonification can help to improve the understanding of acoustic emission techniques for training

  19. A broadband polygonal cloak for acoustic wave designed with linear coordinate transformation.

    PubMed

    Zhu, Rongrong; Zheng, Bin; Ma, Chu; Xu, Jun; Fang, Nicholas; Chen, Hongsheng

    2016-07-01

    Previous acoustic cloaks designed with transformation acoustics always involve inhomogeneous material. In this paper, a design of acoustic polygonal cloak is proposed using linear polygonal transformation method. The designed acoustic polygonal cloak has homogeneous and anisotropic parameters, which is much easier to realize in practice. Furthermore, a possible acoustic metamaterial structure to realize the cloak is proposed. Simulation results on the real structure show that the metamaterial acoustic cloak is effective to reduce the scattering of the object. PMID:27475135

  20. North Pacific Acoustic Laboratory.

    PubMed

    Worcester, Peter F; Spindel, Robert C

    2005-03-01

    A series of long-range acoustic propagation experiments have been conducted in the North Pacific Ocean during the last 15 years using various combinations of low-frequency, wide-bandwidth transmitters and horizontal and vertical line array receivers, including a 2-dimensional array with a maximum vertical aperture of 1400 m and a horizontal aperture of 3600 m. These measurements were undertaken to further our understanding of the physics of low-frequency, broadband propagation and the effects of environmental variability on signal stability and coherence. In this volume some of the results are presented. In the present paper the central issues these experiments have addressed are briefly summarized. PMID:15810685

  1. Acoustic Tooth Cleaner

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.

    1984-01-01

    Acoustically-energized water jet aids in plaque breakdown. Acoustic Wand includes acoustic transducer 1/4 wave plate, and tapered cone. Together elements energize solution of water containing mild abrasive injected into mouth to help prevent calculous buildup.

  2. The Discourse of Parent Involvement in Special Education: A Critical Analysis Linking Policy Documents to the Experiences of Mothers

    ERIC Educational Resources Information Center

    Lai, Yuan; Vadeboncoeur, Jennifer A.

    2013-01-01

    Parent involvement is acknowledged as a crucial aspect of the education of students with special needs. However, the discourse of parent involvement represents parent involvement in limited ways, thereby controlling how and the extent to which parents can be involved in the education of their children. In this article, critical discourse analysis…

  3. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

    Thurman E. Scott, Jr.; Younane Abousleiman

    2004-04-01

    The research during this project has concentrated on developing a correlation between rock deformation mechanisms and their acoustic velocity signature. This has included investigating: (1) the acoustic signature of drained and undrained unconsolidated sands, (2) the acoustic emission signature of deforming high porosity rocks (in comparison to their low porosity high strength counterparts), (3) the effects of deformation on anisotropic elastic and poroelastic moduli, and (4) the acoustic tomographic imaging of damage development in rocks. Each of these four areas involve triaxial experimental testing of weak porous rocks or unconsolidated sand and involves measuring acoustic properties. The research is directed at determining the seismic velocity signature of damaged rocks so that 3-D or 4-D seismic imaging can be utilized to image rock damage. These four areas of study are described in the report: (1) Triaxial compression experiments have been conducted on unconsolidated Oil Creek sand at high confining pressures. (2) Initial experiments on measuring the acoustic emission activity from deforming high porosity Danian chalk were accomplished and these indicate that the AE activity was of a very low amplitude. (3) A series of triaxial compression experiments were conducted to investigate the effects of induced stress on the anisotropy developed in dynamic elastic and poroelastic parameters in rocks. (4) Tomographic acoustic imaging was utilized to image the internal damage in a deforming porous limestone sample. Results indicate that the deformation damage in rocks induced during laboratory experimentation can be imaged tomographically in the laboratory. By extension the results also indicate that 4-D seismic imaging of a reservoir may become a powerful tool for imaging reservoir deformation (including imaging compaction and subsidence) and for imaging zones where drilling operation may encounter hazardous shallow water flows.

  4. Imaging marine geophysical environments with vector acoustics.

    PubMed

    Lindwall, Dennis

    2006-09-01

    Using vector acoustic sensors for marine geoacoustic surveys instead of the usual scalar hydrophones enables one to acquire three-dimensional (3D) survey data with instrumentation and logistics similar to current 2D surveys. Vector acoustic sensors measure the sound wave direction directly without the cumbersome arrays that hydrophones require. This concept was tested by a scaled experiment in an acoustic water tank that had a well-controlled environment with a few targets. Using vector acoustic data from a single line of sources, the three-dimensional tank environment was imaged by directly locating the source and all reflectors. PMID:17004497

  5. Acoustic Emphasis in Four Year Olds

    ERIC Educational Resources Information Center

    Wonnacott, Elizabeth; Watson, Duane G.

    2008-01-01

    Acoustic emphasis may convey a range of subtle discourse distinctions, yet little is known about how this complex ability develops in children. This paper presents a first investigation of the factors which influence the production of acoustic prominence in young children's spontaneous speech. In a production experiment, SVO sentences were…

  6. Acoustic transducer

    DOEpatents

    Drumheller, D.S.

    1997-12-30

    An acoustic transducer is described comprising a one-piece hollow mandrel into the outer surface of which is formed a recess with sides perpendicular to the central axis of the mandrel and separated by a first distance and with a bottom parallel to the central axis and within which recess are a plurality of washer-shaped discs of a piezoelectric material and at least one disc of a temperature-compensating material with the discs being captured between the sides of the recess in a pre-stressed interference fit, typically at 2,000 psi of compressive stress. The transducer also includes a power supply and means to connect to a measurement device. The transducer is intended to be used for telemetry between a measurement device located downhole in an oil or gas well and the surface. The transducer is of an construction that is stronger with fewer joints that could leak fluids into the recess holding the piezoelectric elements than is found in previous acoustic transducers. 4 figs.

  7. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S.

    1997-01-01

    An acoustic transducer comprising a one-piece hollow mandrel into the outer surface of which is formed a recess with sides perpendicular to the central axis of the mandrel and separated by a first distance and with a bottom parallel to the central axis and within which recess are a plurality of washer-shaped discs of a piezoelectric material and at least one disc of a temperature-compensating material with the discs being captured between the sides of the recess in a pre-stressed interference fit, typically at 2000 psi of compressive stress. The transducer also includes a power supply and means to connect to a measurement device. The transducer is intended to be used for telemetry between a measurement device located downhole in an oil or gas well and the surface. The transducer is of an construction that is stronger with fewer joints that could leak fluids into the recess holding the piezoelectric elements than is found in previous acoustic transducers.

  8. Scanning tomographic acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Hua

    2002-11-01

    This paper provides an overview of the design and development of the scanning tomographic acoustic microscopy (STAM). This research effort spans over a period of more than 12 years, which successfully elevated the acoustic microscopy from the traditional intensity-mapping mode to the level of holographic and tomographic imaging. The tomographic imaging capability of STAM was developed on the platform of the scanning laser acoustic microscope (SLAM), which operates in a coherent transmission mode with plane-wave illumination and scanning laser wavefield detection. The image formation techniques were based on the backward propagation method implemented in the plane-to-plane format. In this paper, the key elements of the design and development, including the modification of the data-acquisition hardware, implementation of image reconstruction algorithms for multiple-frequency and multiple-angle tomography, and the high-precision phase-correction and image registration techniques for the superposition of coherent sub-images, will be discussed. Results of full-scale experiments will also be included to demonstrate the capability of holographic and tomographic image formation in microscopic scale.

  9. Acoustically enhanced heat transport.

    PubMed

    Ang, Kar M; Yeo, Leslie Y; Friend, James R; Hung, Yew Mun; Tan, Ming K

    2016-01-01

    We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ∼ 10(6) Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration amplitudes (ξs ∼ 10(-9) m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration amplitude (ξs ∼ 10(-8) m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement amplitude on the order of 10(-8) m with 10(6) Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation. PMID:26827343

  10. Acoustically enhanced heat transport

    NASA Astrophysics Data System (ADS)

    Ang, Kar M.; Yeo, Leslie Y.; Friend, James R.; Hung, Yew Mun; Tan, Ming K.

    2016-01-01

    We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ˜ 106 Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration amplitudes (ξs ˜ 10-9 m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration amplitude (ξs ˜ 10-8 m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement amplitude on the order of 10-8 m with 106 Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation.

  11. Spatiotemporally resolved granular acoustics

    NASA Astrophysics Data System (ADS)

    Owens, Eli; Daniels, Karen

    2011-03-01

    Acoustic techniques provide a non-invasive method of characterizing granular material properties; however, there are many challenges in formulating accurate models of sound propagation due to the inherently heterogeneous nature of granular materials. In order to quantify acoustic responses in space and time, we perform experiments in a photoelastic granular material in which the internal stress pattern (in the form of force chains) is visible. We utilize two complementary methods, high-speed imaging and piezoelectric transduction, to provide particle-scale measurements of the amplitude of the acoustic wave. We observe that the average wave amplitude is largest within particles experiencing the largest forces. The force-dependence of this amplitude is in qualitative agreement with a simple Hertzian-like model for contact area. In addition, we investigate the power spectrum of the propagating signal using the piezoelectric sensors. For a Gaussian wave packet input, we observe a broad spectrum of transmitted frequencies below the driving frequency, and we quantify the characteristic frequencies and corresponding length scales of our material as the system pressure is varied.

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

    NASA Technical Reports Server (NTRS)

    Lyell, Margaret J.

    1992-01-01

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

  13. Droplet Vaporization In A Levitating Acoustic Field

    NASA Technical Reports Server (NTRS)

    Ruff, G. A.; Liu, S.; Ciobanescu, I.

    2003-01-01

    Combustion experiments using arrays of droplets seek to provide a link between single droplet combustion phenomena and the behavior of complex spray combustion systems. Both single droplet and droplet array studies have been conducted in microgravity to better isolate the droplet interaction phenomena and eliminate or reduce the effects of buoyancy-induced convection. In most experiments involving droplet arrays, the droplets are supported on fibers to keep them stationary and close together before the combustion event. The presence of the fiber, however, disturbs the combustion process by introducing a source of heat transfer and asymmetry into the configuration. As the number of drops in a droplet array increases, supporting the drops on fibers becomes less practical because of the cumulative effect of the fibers on the combustion process. To eliminate the effect of the fiber, several researchers have conducted microgravity experiments using unsupported droplets. Jackson and Avedisian investigated single, unsupported drops while Nomura et al. studied droplet clouds formed by a condensation technique. The overall objective of this research is to extend the study of unsupported drops by investigating the combustion of well-characterized drop clusters in a microgravity environment. Direct experimental observations and measurements of the combustion of droplet clusters would provide unique experimental data for the verification and improvement of spray combustion models. In this work, the formation of drop clusters is precisely controlled using an acoustic levitation system so that dilute, as well as dense clusters can be created and stabilized before combustion in microgravity is begun. While the low-gravity test facility is being completed, tests have been conducted in 1-g to characterize the effect of the acoustic field on the vaporization of single and multiple droplets. This is important because in the combustion experiment, the droplets will be formed and

  14. On the right path? Exploring the experiences and opinions of clinicians involved in developing and implementing HealthPathways Barwon.

    PubMed

    Mansfield, Sarah J; Quirk, Frances; von Treuer, Kathryn; Gill, Gerard

    2016-04-01

    The aims of this paper are to present the findings of a process evaluation exploring the experiences and opinions of clinicians who have been involved in the HealthPathways Barwon clinical workgroups and discuss implications for further development of the program, as well as regional health service initiatives more broadly. HealthPathways Barwon is a web-based program comprising locally agreed-upon evidence-based clinical pathways that assist with assessment, management and region-specific referral for various clinical conditions. Clinical workgroup members participated in focus groups. Coding and thematic analysis were performed and findings were compared with similar evaluations of HealthPathways in other jurisdictions. Five broad themes emerged from the focus group, each with several subthemes: (1) purpose of HealthPathways; (2) workgroup process; (3) barriers and facilitators to HealthPathways use; (4) impact of HealthPathways on clinical practice; and (5) measuring performance. Findings of particular interest were that the perceived drivers for implementation of HealthPathways Barwon are broad, HealthPathways Barwon is viewed positively by clinicians, the workgroup process itself has a positive impact on relationships between primary and secondary care clinicians, existing habits of clinicians are a major barrier to adoption of HealthPathways Barwon, the sustainability of HealthPathways Barwon is a concern and it is difficult to measure the outcomes of HealthPathways. Although HealthPathways Barwon is viewed positively by clinicians and is seen to have the potential to address many issues at the primary-secondary care interface, successful implementation and uptake will depend on buy-in from clinicians, as well as continuous evaluation to inform improved development and implementation. More broadly, health service initiatives like HealthPathways Barwon require longer-term certainty of funding and administration to become established and produce meaningful

  15. Protective Behaviour of Citizens to Transport Accidents Involving Hazardous Materials: A Discrete Choice Experiment Applied to Populated Areas nearby Waterways

    PubMed Central

    de Bekker-Grob, Esther W.; Bergstra, Arnold D.; Bliemer, Michiel C. J.; Trijssenaar-Buhre, Inge J. M.; Burdorf, Alex

    2015-01-01

    Background To improve the information for and preparation of citizens at risk to hazardous material transport accidents, a first important step is to determine how different characteristics of hazardous material transport accidents will influence citizens’ protective behaviour. However, quantitative studies investigating citizens’ protective behaviour in case of hazardous material transport accidents are scarce. Methods A discrete choice experiment was conducted among subjects (19–64 years) living in the direct vicinity of a large waterway. Scenarios were described by three transport accident characteristics: odour perception, smoke/vapour perception, and the proportion of people in the environment that were leaving at their own discretion. Subjects were asked to consider each scenario as realistic and to choose the alternative that was most appealing to them: staying, seeking shelter, or escaping. A panel error component model was used to quantify how different transport accident characteristics influenced subjects’ protective behaviour. Results The response was 44% (881/1,994). The predicted probability that a subject would stay ranged from 1% in case of a severe looking accident till 62% in case of a mild looking accident. All three transport accident characteristics proved to influence protective behaviour. Particularly a perception of strong ammonia or mercaptan odours and visible smoke/vapour close to citizens had the strongest positive influence on escaping. In general, ‘escaping’ was more preferred than ‘seeking shelter’, although stated preference heterogeneity among subjects for these protective behaviour options was substantial. Males were less willing to seek shelter than females, whereas elderly people were more willing to escape than younger people. Conclusion Various characteristics of transport accident involving hazardous materials influence subjects’ protective behaviour. The preference heterogeneity shows that information needs

  16. Acoustic cryocooler

    DOEpatents

    Swift, Gregory W.; Martin, Richard A.; Radenbaugh, Ray

    1990-01-01

    An acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effective to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15-60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintian a cooling load of 5 W at 80 K.

  17. 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.

  18. Acoustic hemostasis

    NASA Astrophysics Data System (ADS)

    Crum, L.; Andrew, M.; Bailey, M.; Beach, K.; Brayman, A.; Curra, F.; Kaczkowski, P.; Kargl, S.; Martin, R.; Vaezy, S.

    2003-04-01

    Over the past several years, the Center for Industrial and Medical Ultrasound (CIMU) at the Applied Physics Laboratory in the University of Washington has undertaken a broad research program in the general area of High Intensity Focused Ultrasound (HIFU). Our principal emphasis has been on the use of HIFU to induce hemostasis; in particular, CIMU has sought to develop a small, lightweight, portable device that would use ultrasound for both imaging and therapy. Such a technology is needed because nearly 50% of combat casualty mortality results from exsanguinations, or uncontrolled bleeding. A similar percentage occurs for civilian death due to trauma. In this general review, a presentation of the general problem will be given, as well as our recent approaches to the development of an image-guided, transcutaneous, acoustic hemostasis device. [Work supported in part by the USAMRMC, ONR and the NIH.

  19. Acoustic telemetry.

    SciTech Connect

    Drumheller, Douglas Schaeffer; Kuszmaul, Scott S.

    2003-08-01

    Broadcasting messages through the earth is a daunting task. Indeed, broadcasting a normal telephone conversion through the earth by wireless means is impossible with todays technology. Most of us don't care, but some do. Industries that drill into the earth need wireless communication to broadcast navigation parameters. This allows them to steer their drill bits. They also need information about the natural formation that they are drilling. Measurements of parameters such as pressure, temperature, and gamma radiation levels can tell them if they have found a valuable resource such as a geothermal reservoir or a stratum bearing natural gas. Wireless communication methods are available to the drilling industry. Information is broadcast via either pressure waves in the drilling fluid or electromagnetic waves in the earth and well tubing. Data transmission can only travel one way at rates around a few baud. Given that normal Internet telephone modems operate near 20,000 baud, these data rates are truly very slow. Moreover, communication is often interrupted or permanently blocked by drilling conditions or natural formation properties. Here we describe a tool that communicates with stress waves traveling through the steel drill pipe and production tubing in the well. It's based on an old idea called Acoustic Telemetry. But what we present here is more than an idea. This tool exists, it's drilled several wells, and it works. Currently, it's the first and only acoustic telemetry tool that can withstand the drilling environment. It broadcasts one way over a limited range at much faster rates than existing methods, but we also know how build a system that can communicate both up and down wells of indefinite length.

  20. Cryogenic acoustic loss of pure and alloyed titanium

    NASA Astrophysics Data System (ADS)

    Matacz, A. L.; Veitch, P. J.; Blair, D. G.

    Low acoustic loss, high yield strength cryogenic materials are required for various high precision experiments, resonant-bar gravitational radiation antennae in particular. We report here acoustic loss measurements of commerically pure and alloyed titanium samples between 4.2 and 300 K. It is shown that machining damage of the surface significantly increased the acoustic loss of pure titanium, particularly below 100 K, and that the high strength alloy Ti-6AI-4V had significantly greater acoustic loss than pure titanium.

  1. Broadband acoustic scattering measurements of underwater unexploded ordnance (UXO).

    PubMed

    Bucaro, J A; Houston, B H; Saniga, M; Dragonette, L R; Yoder, T; Dey, S; Kraus, L; Carin, L

    2008-02-01

    In order to evaluate the potential for detection and identification of underwater unexploded ordnance (UXO) by exploiting their structural acoustic response, we carried out broadband monostatic scattering measurements over a full 360 degrees on UXO's (two mortar rounds, an artillery shell, and a rocket warhead) and false targets (a cinder block and a large rock). The measurement band, 1-140 kHz, includes a low frequency structural acoustics region in which the wavelengths are comparable to or larger than the target characteristic dimensions. In general, there are aspects that provide relatively high target strength levels ( approximately -10 to -15 dB), and from our experience the targets should be detectable in this structural acoustics band in most acoustic environments. The rigid body scattering was also calculated for one UXO in order to highlight the measured scattering features involving elastic responses. The broadband scattering data should be able to support feature-based separation of UXO versus false targets and identification of various classes of UXO as well. PMID:18247878

  2. Dynamic acoustic tractor beams

    NASA Astrophysics Data System (ADS)

    Mitri, F. G.

    2015-03-01

    Pulling a sphere and vibrating it around an equilibrium position by amplitude-modulation in the near-field of a single finite circular piston transducer is theoretically demonstrated. Conditions are found where a fluid hexane sphere (with arbitrary radius) chosen as an example, centered on the axis of progressive propagating waves and submerged in non-viscous water, experiences an attractive (steady) force pulling it towards the transducer, as well as an oscillatory force forcing it to vibrate back-and-forth. Numerical predictions for the dynamic force illustrate the theory and suggest an innovative method in designing dynamic acoustical tractor beams.

  3. Dynamic acoustic tractor beams

    SciTech Connect

    Mitri, F. G.

    2015-03-07

    Pulling a sphere and vibrating it around an equilibrium position by amplitude-modulation in the near-field of a single finite circular piston transducer is theoretically demonstrated. Conditions are found where a fluid hexane sphere (with arbitrary radius) chosen as an example, centered on the axis of progressive propagating waves and submerged in non-viscous water, experiences an attractive (steady) force pulling it towards the transducer, as well as an oscillatory force forcing it to vibrate back-and-forth. Numerical predictions for the dynamic force illustrate the theory and suggest an innovative method in designing dynamic acoustical tractor beams.

  4. Acoustically Enhanced Electroplating Being Developed

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C.

    2002-01-01

    In cooperation with the NASA Glenn Research Center, Alchemitron Corp. is developing the Acoustically Enhanced Electroplating Process (AEEP), a new technique of employing nonlinear ultrasonics to enhance electroplating. The applications range from electroplating full-panel electronic circuit boards to electroplating microelectronics and microelectromechanical systems (MEMS) devices. In a conventional plating process, the surface area to be plated is separated from the nonplated areas by a temporary mask. The mask may take many forms, from a cured liquid coating to a simple tape. Generally, the mask is discarded when the plating is complete, creating a solid waste product that is often an environmental hazard. The labor and materials involved with the layout, fabrication, and tooling of masks is a primary source of recurring and nonrecurring production costs. The objective of this joint effort, therefore, is to reduce or eliminate the need for masks. AEEP improves selective plating processes by using directed beams of high-intensity acoustic waves to create nonlinear effects that alter the fluid dynamic and thermodynamic behavior of the plating process. It relies on two effects: acoustic streaming and acoustic heating. Acoustic streaming is observed when a high-intensity acoustic beam creates a liquid current within the beam. The liquid current can be directed as the beam is directed and, thus, users can move liquid around as desired without using pumps and nozzles. The current of the electroplating electrolyte, therefore, can be directed at distinct target areas where electroplating is desired. The current delivers fresh electrolyte to the target area while flushing away the spent electrolyte. This dramatically increases the plating rate in the target area. In addition, acoustic heating of both the liquid in the beam and the target surface increases the chemical reaction rate, which further increases the plating rate. The combined effects of acoustic streaming and

  5. The Gelation of Polyvinyl Alcohol with Borax: A Novel Class Participation Experiment Involving the Preparation and Properties of a "Slime."

    ERIC Educational Resources Information Center

    Casassa, E. Z.; And Others

    1986-01-01

    Background information, procedures used, and typical results obtained are provided for an experiment in which students prepare and study the characteristics of a "slime." A list of general, inorganic, and polymer chemistry concepts fostered in the experiment is included. (JN)

  6. Acoustic metamaterials for sound mitigation

    NASA Astrophysics Data System (ADS)

    Assouar, Badreddine; Oudich, Mourad; Zhou, Xiaoming

    2016-05-01

    We provide theoretical and numerical analyses of the behavior of a plate-type acoustic metamaterial considered in an air-borne sound environment in view of sound mitigation application. Two configurations of plate are studied, a spring-mass one and a pillar system-based one. The acoustic performances of the considered systems are investigated with different approaches and show that a high sound transmission loss (STL) up to 82 dB is reached with a metamaterial plate with a thickness of 0.5 mm. The physical understanding of the acoustic behavior of the metamaterial partition is discussed based on both air-borne and structure-borne approaches. Confrontation between the STL, the band structure, the displacement fields and the effective mass density of the plate metamaterial is made to have a complete physical understanding of the different mechanisms involved. xml:lang="fr"

  7. Involvement in Campus Activities and the Retention of First-Year College Students. The First-Year Experience Monograph Series.

    ERIC Educational Resources Information Center

    Skipper, Tracy L., Ed.; Argo, Roxanne, Ed.

    The chapters of this monograph offer insights into educationally purposeful out-of-class activities and the impact they have on the student experience. It also provides future directions for the campus activities field and identifies ways to improve the educational experience of first-year students to enhance their scholarly experience and to…

  8. Acoustic constituents of prosodic typology

    NASA Astrophysics Data System (ADS)

    Komatsu, Masahiko

    Different languages sound different, and considerable part of it derives from the typological difference of prosody. Although such difference is often referred to as lexical accent types (stress accent, pitch accent, and tone; e.g. English, Japanese, and Chinese respectively) and rhythm types (stress-, syllable-, and mora-timed rhythms; e.g. English, Spanish, and Japanese respectively), it is unclear whether these types are determined in terms of acoustic properties, The thesis intends to provide a potential basis for the description of prosody in terms of acoustics. It argues for the hypothesis that the source component of the source-filter model (acoustic features) approximately corresponds to prosody (linguistic features) through several experimental-phonetic studies. The study consists of four parts. (1) Preliminary experiment: Perceptual language identification tests were performed using English and Japanese speech samples whose frequency spectral information (i.e. non-source component) is heavily reduced. The results indicated that humans can discriminate languages with such signals. (2) Discussion on the linguistic information that the source component contains: This part constitutes the foundation of the argument of the thesis. Perception tests of consonants with the source signal indicated that the source component carries the information on broad categories of phonemes that contributes to the creation of rhythm. (3) Acoustic analysis: The speech samples of Chinese, English, Japanese, and Spanish, differing in prosodic types, were analyzed. These languages showed difference in acoustic characteristics of the source component. (4) Perceptual experiment: A language identification test for the above four languages was performed using the source signal with its acoustic features parameterized. It revealed that humans can discriminate prosodic types solely with the source features and that the discrimination is easier as acoustic information increases. The

  9. Developments and field tests of low-frequency portable acoustic transducers for a mobile exploration and time lapse experiment of a sea-bottom reservoir

    NASA Astrophysics Data System (ADS)

    Tsuruga, K.; Kasahara, J.; Hasada, Y.; Kondo, H.

    2013-12-01

    Depth, scale and resolutions of geophysical explorations for mineral resources are controlled by transmitted seismic energy and wavelength (frequency range). Most explorations in marine have been conducted by survey ship system with arrayed acoustic sources whose dominant frequency range is about 10 to 500 Hz. On the other hand, for shallow parts of sea bottom structure survey, some sub-bottom profilers with frequency range around 3.5kHz are used. To monitor a time lapse of a sea bottom reservoir such as an oil, gas, or methane hydrate reservoir as well as to exploit a mobile survey near a sea bottom by AUVs, it is necessary to use a broadband portable acoustic transducer with a dominant frequency range of 500 Hz to 5 kHz. We have been developing several types of portable acoustic transducers and a transmitting and recording system which is accurately controlled by a GPS clock (Tsuruga et al., 2012). In this pater, we report the new broadband acoustic portable transducers which have larger power than the original cylindrical acoustic transducers in a low frequency range (<5 kHz), partly funded by JOGMEC, and show the preliminary results of field tests at the shallow sea bottom around 32 m deep by means of the transducers and hydrophone receivers array. Each transducer repeatedly transmitted Chirp signals with a unit period of 500 msec in two frequency ranges of 0.5k-4.5kHz and 4k-16kHz . We stacked 500-ms data by 28 times to obtain a transfer function of each source-receiver pair in the time and frequency domains. The preliminary results suggest as the follows: (i) it is successful to broaden the frequency bandwidth (i.e., 2k-10kHz) by extending a geometrical resonance length of a cylindrical acoustic transducers, and (ii) the observation at the sea bottom with accurately controlled timing systems of transmitter and data-logger is very useful to identify the stable and/or unstable seismic phases, that is, waves propagating in a underground and/or in a sea water as

  10. Acoustic hemostasis

    NASA Astrophysics Data System (ADS)

    Crum, Lawrence; Beach, Kirk; Carter, Stephen; Chandler, Wayne; Curra, Francesco; Kaczkowski, Peter; Keilman, George; Khokhlova, Vera; Martin, Roy; Mourad, Pierre; Vaezy, Shahram

    2000-07-01

    In cases of severe injury, physicians speak of a "golden hour"—a brief grace period in which quickly applied, proper therapy can save the life of the patient. Much of this mortality results from exsanguination, i.e., bleeding to death—often from internal hemorrhage. The inability of a paramedic to treat breaches in the vascular system deep within the body or to stem the loss of blood from internal organs is a major reason for the high level of mortality associated with blunt trauma. We have undertaken an extensive research program to treat the problem of internal bleeding. Our approach is as follows: (a) We use scanning ultrasound to identify internal bleeding and hemorrhage, (b) we use ultrasound imaging to locate specific breaches in the vascular system, both from damaged vessels and gross damage to the capillary bed, and (c) we use High Intensity Focused Ultrasound (HIFU) to treat the damaged region and to induce hemostasis. We present a general review of this research with some emphasis on the role of nonlinear acoustics.

  11. Seismicity triggered by the olivine-spinel transition: New insights from combined XRD and acoustic emission monitoring during deformation experiments in Mg2GeO4

    NASA Astrophysics Data System (ADS)

    Schubnel, A. J.; Hilairet, N.; Gasc, J.; Héripré, E.; Brunet, F.; Wang, Y.

    2010-12-01

    Polycrystalline Mg2GeO4-olivine has been deformed (strain rates from 2.10-4/s to 10-5/s) in the deformation-DIA in 13-BM-D at GSECARS (Advanced Photon Source) at ca. 2 GPa confining pressure for temperatures between 973 and 1573 K (i.e., in the Mg2GeO4-ringwoodite field). Stress, advancement of transformation, and strain were measured in-situ using X-ray diffraction (XRD) and imaging, and acoustic emissions (AE) full waveforms were recorded simultaneously. When differential stress is applied (ca. 1- to 2 GPa) and temperature is increased, the very beginning of the transformation to the ringwoodite structure (as evidenced by in situ XRD) is accompanied by AE bursts which locate within the sample. At high strain rates (>10-4/s) and low temperatures (800-900 degrees C), the number of AEs is comparable, if not larger, to that observed during the cold compression of quartz grains. The largest events always occur at a temperature slightly below that of appearance of the ringwoodite-structure phase on the XRD images patterns. This suggests that AEs are generated while the transition is still nucleation controlled (pseudo-martensitic stage). During stress-relaxation periods, the rate of AE triggering decreases, but does not completely vanish. The AE production rate increases again as soon as deformation is started again. Importantly, we still observed very large AEs at strain rates as low as approx. 10-5/ s. At these early stages of the transformation, the samples did not show any macroscopic rheological weakening. Focal mechanism analysis of the largest AEs showed that they are all of shear type, some being even pure double couple. They radiate about the same amount of energy as typically recorded during fast crack propagation in amorphous glass material. This suggests that they cannot only originate from the martensitic nucleation of oriented spinel-lamellae within a single germanium olivine crystal. Preliminary microstructural analysis (SEM and EBSD) highlights the

  12. Musical acoustics demonstrations

    NASA Astrophysics Data System (ADS)

    Hoekje, P. L.

    2003-10-01

    The ASA Musical Acoustics Demonstrations website (trial version at http://www.bw.edu/~phoekje) includes sound files, video clips, program code listings, and other material for demonstrations related to musical acoustics. Many of the sound demonstrations may be experienced either as expositions, in which the phenomena are explained before they are presented, or as experiments, in which the explanation comes after listeners have had the opportunity to draw their own conclusions. Suggestions are provided for apparatus construction and classroom experiments, as well as for building simple musical instruments. Software is recommended if it is available free and compatible with multiple personal computer operating systems. For example, Audacity (http://audacity.sourceforce.net) is a sound file editor and analyzer that can be used to visually represent sounds and manipulate them. Source files are included for the synthesized sound examples, which were created in Csound (http://csounds.com), so that interested users may create their own variations. Source code is also included for visual demonstrations created in Visual Python and Python (http://www.python.org), an efficient, high level programming language. Suggestions, criticisms, and contributions are always welcome! [Work supported by ASA and Baldwin-Wallace College.

  13. Experimental investigation of cryogenic flame dynamics under transverse acoustic modulations

    NASA Astrophysics Data System (ADS)

    Méry, Yoann; Hakim, Layal; Scouflaire, Philippe; Vingert, Lucien; Ducruix, Sébastien; Candel, Sébastien

    2013-01-01

    The present investigation is focused on high-frequency combustion instabilities coupled by transverse acoustic modes. This phenomenon has been observed during the development of many liquid rocket engines and other high performance devices. Such instabilities induce an unsteady heat release which leads in many cases to a rapid intensification of heat fluxes to the thrust chamber walls, causing fatal damage and a spectacular destruction of the propulsion system. One central objective of this effort is to observe and understand the physical processes leading the coupling between acoustics and combustion, and resulting in the growth of such instabilities. Experiments carried out on the Mascotte testbed at ONERA serve to identify the main processes involved and bring forth mechanisms taking place when an engine becomes unstable. Hot fire experiments are carried out in a model scale combustor reproducing many of the conditions prevailing in unstable rocket engines. Subcritical and transcritical cryogenic jets are injected in a multiple injector combustion chamber (MIC). This system is fed with LOx and methane through five injection units. The flames formed in this configuration are modulated by an acoustic wave with an amplitude of several bars. This is obtained with a new Very Large Amplitude Modulator (VHAM) capable of generating acoustic mode amplitudes representative of those found in actual engine undergoing HF instabilities. It is shown first that the strength of the acoustic field and the frequency range of oscillation (1 kHz-3.5 kHz) are consistent with rocket instability observations. Conditions where a feedback of the flame on the acoustic field occurs are obtained. High speed diagnostics indicates that the velocity field dramatically enhances the atomization process. The liquid core length is strongly reduced. At moderate amplitudes, the liquid jets are flattened in the spanwise direction and heat release takes place in two sheets neighboring the dense core

  14. Finite Difference Simulations of Acoustic and Gravity Wave Propagation in Mars Atmosphere: Applications to INSIGHT NASA Mission and Mars Microphone Experiments

    NASA Astrophysics Data System (ADS)

    Garcia, R.; Brissaud, Q.; Martin, R.; Rolland, L. M.; Komatitsch, D.

    2015-12-01

    A simulation tool of acoustic and gravity wave propagation through finite differences is applied to the case of Mars atmosphere.The details of the code and its validation for Earth atmosphere are presented in session SA003.The simulations include the modeling of both acoustic and gravity waves in the same run, an effects of exponential density decrease, winds and attenuation.The application to Mars requires the inclusion of a specific attenuation effect related to the relaxation induced by vibrational modes of carbon dioxide molecules.Two different applications are presented demonstrating the ability of the simulation tool to work at very different scale length and frequencies.First the propagation of acoustic and gravity waves due to a bolide explosion in the atmosphere of Mars are simulated.This case has a direct application to the atmospheric pressure and seismic measurements that will be performed by INSIGHT NASA discovery mission next year.Then, we also present simulations of sound wave propagation on a scale of meters that can be used to infer the feasability microphone measurements for future Mars missions.

  15. Acoustic source for generating an acoustic beam

    DOEpatents

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

    2016-05-31

    An acoustic source for generating an acoustic beam includes a housing; a plurality of spaced apart piezo-electric layers disposed within the housing; and a non-linear medium filling between the plurality of layers. Each of the plurality of piezoelectric layers is configured to generate an acoustic wave. The non-linear medium and the plurality of piezo-electric material layers have a matching impedance so as to enhance a transmission of the acoustic wave generated by each of plurality of layers through the remaining plurality of layers.

  16. Acoustic Holography

    NASA Astrophysics Data System (ADS)

    Kim, Yang-Hann

    One of the subtle problems that make noise control difficult for engineers is the invisibility of noise or sound. A visual image of noise often helps to determine an appropriate means for noise control. There have been many attempts to fulfill this rather challenging objective. Theoretical (or numerical) means for visualizing the sound field have been attempted, and as a result, a great deal of progress has been made. However, most of these numerical methods are not quite ready for practical applications to noise control problems. In the meantime, rapid progress with instrumentation has made it possible to use multiple microphones and fast signal-processing systems. Although these systems are not perfect, they are useful. A state-of-the-art system has recently become available, but it still has many problematic issues; for example, how can one implement the visualized noise field. The constructed noise or sound picture always consists of bias and random errors, and consequently, it is often difficult to determine the origin of the noise and the spatial distribution of the noise field. Section 26.2 of this chapter introduces a brief history, which is associated with sound visualization, acoustic source identification methods and what has been accomplished with a line or surface array. Section 26.2.3 introduces difficulties and recent studies, including de-Dopplerization and de-re verberation methods, both essential for visualizing a moving noise source, such as occurs for cars or trains. This section also addresses what produces ambiguity in realizing real sound sources in a room or closed space. Another major issue associated with sound/noise visualization is whether or not we can distinguish between mutual dependencies of noise in space (Sect. 26.2.4); for example, we are asked to answer the question, Can we see two birds singing or one bird with two beaks?

  17. Acoustic Holography

    NASA Astrophysics Data System (ADS)

    Kim, Yang-Hann

    One of the subtle problems that make noise control difficult for engineers is the invisibility of noise or sound. A visual image of noise often helps to determine an appropriate means for noise control. There have been many attempts to fulfill this rather challenging objective. Theoretical (or numerical) means for visualizing the sound field have been attempted, and as a result, a great deal of progress has been made. However, most of these numerical methods are not quite ready for practical applications to noise control problems. In the meantime, rapid progress with instrumentation has made it possible to use multiple microphones and fast signal-processing systems. Although these systems are not perfect, they are useful. A state-of-the-art system has recently become available, but it still has many problematic issues; for example, how can one implement the visualized noise field. The constructed noise or sound picture always consists of bias and random errors, and consequently, it is often difficult to determine the origin of the noise and the spatial distribution of the noise field. Section 26.2 of this chapter introduces a brief history, which is associated with "sound visualization," acoustic source identification methods and what has been accomplished with a line or surface array. Section 26.2.3 introduces difficulties and recent studies, including de-Dopplerization and de-reverberation methods, both essentialfor visualizing a moving noise source, such as occurs for cars or trains. This section also addresses what produces ambiguity in realizing real sound sources in a room or closed space. Another major issue associated with sound/noise visualization is whether or not we can distinguish between mutual dependencies of noise in space (Sect. 26.2.4); for example, we are asked to answer the question, "Can we see two birds singing or one bird with two beaks?"

  18. To do, to have, or to share? Valuing experiences over material possessions depends on the involvement of others.

    PubMed

    Caprariello, Peter A; Reis, Harry T

    2013-02-01

    Recent evidence indicates that spending discretionary money with the intention of acquiring life experiences-events that one lives through-makes people happier than spending money with the intention of acquiring material possessions-tangible objects that one obtains and possesses. We propose and show that experiences are more likely to be shared with others, whereas material possessions are more prone to solitary use and that this distinction may account for their differential effects on happiness. In 4 studies, we present evidence demonstrating that the inclusion of others is a key dimension of how people derive happiness from discretionary spending. These studies showed that when the social-solitary and experiential-material dimensions were considered simultaneously, social discretionary spending was favored over solitary discretionary spending, whereas experiences showed no happiness-producing advantage relative to possessions. Furthermore, whereas spending money on socially shared experiences was valued more than spending money on either experiences enacted alone or material possessions, solitary experiences were no more valued than material possessions. Together, these results extend and clarify the basic findings of prior research and add to growing evidence that the social context of experiences is critical for their effects on happiness. PMID:23276272

  19. 3D Simulation as a Learning Environment for Acquiring the Skill of Self-Management: An Experience Involving Spanish University Students of Education

    ERIC Educational Resources Information Center

    Cela-Ranilla, Jose María; Esteve-Gonzalez, Vanessa; Esteve-Mon, Francesc; Gisbert-Cervera, Merce

    2014-01-01

    In this study we analyze how 57 Spanish university students of Education developed a learning process in a virtual world by conducting activities that involved the skill of self-management. The learning experience comprised a serious game designed in a 3D simulation environment. Descriptive statistics and non-parametric tests were used in the…

  20. Perturbation measurement of waveguides for acoustic thermometry

    NASA Astrophysics Data System (ADS)

    Lin, H.; Feng, X. J.; Zhang, J. T.

    2013-09-01

    Acoustic thermometers normally embed small acoustic transducers in the wall bounding a gas-filled cavity resonator. At high temperature, insulators of transducers loss electrical insulation and degrade the signal-to-noise ratio. One essential solution to this technical trouble is to couple sound by acoustic waveguides between resonator and transducers. But waveguide will break the ideal acoustic surface and bring perturbations(Δf+ig) to the ideal resonance frequency. The perturbation model for waveguides was developed based on the first-order acoustic theory in this paper. The frequency shift Δf and half-width change g caused by the position, length and radius of waveguides were analyzed using this model. Six different length of waveguides (52˜1763 mm) were settled on the cylinder resonator and the perturbation (Δf+ig) were measured at T=332 K and p=250˜500 kPa. The experiment results agreed with the theoretical prediction very well.

  1. Planar and nonplanar ion acoustic shock waves in relativistic degenerate astrophysical electron-positron-ion plasmas

    SciTech Connect

    Ata-ur-Rahman,; Qamar, A.; Ali, S.; Mirza, Arshad M.

    2013-04-15

    We have studied the propagation of ion acoustic shock waves involving planar and non-planar geometries in an unmagnetized plasma, whose constituents are non-degenerate ultra-cold ions, relativistically degenerate electrons, and positrons. By using the reductive perturbation technique, Korteweg-deVries Burger and modified Korteweg-deVries Burger equations are derived. It is shown that only compressive shock waves can propagate in such a plasma system. The effects of geometry, the ion kinematic viscosity, and the positron concentration are examined on the ion acoustic shock potential and electric field profiles. It is found that the properties of ion acoustic shock waves in a non-planar geometry significantly differ from those in planar geometry. The present study has relevance to the dense plasmas, produced in laboratory (e.g., super-intense laser-dense matter experiments) and in dense astrophysical objects.

  2. Statistical Inversion of Acoustic Backscatter Profile Data with Sediment-Induced Attenuation

    NASA Astrophysics Data System (ADS)

    Wilson, G.; Hay, A. E.

    2014-12-01

    Multi-frequency acoustic backscatter inversion is a proven technique for measuring profiles of suspended sediment size and concentration. However, current inversion techniques tend to become inaccurate when sediment-induced acoustic attenuation is high (e.g., large suspended concentrations). In such cases, statistical fluctuations cause an accumulation of errors along the observed profile, which leads to an ill-posed inverse problem, even if the intrinsic properties of the scatterers are exactly known. Here, a statistical inversion methodology is introduced in which the ill-posed problem is regularized by explicitly considering the uncertainty of the observational data. The method uses the Extended Kalman Filter to estimate the propagation of uncertainty through the profile, followed by a variational smoothing step. This approach is shown to successfully estimate concentration and size profiles in cases where direct inversion fails. The method is also applied to laboratory experiments involving a multi-frequency megahertz acoustic profiler (MFDop) measuring a sediment-laden jet.

  3. What Is an Acoustic Neuroma

    MedlinePlus

    ... Acoustic Neuroma An acoustic neuroma, also called a vestibular schwannoma, is a rare benign tumor of the ... Acoustic Neuroma? An acoustic neuroma, known as a vestibular schwannoma, is a benign (non-cancerous) growth that ...

  4. Canonical Acoustics and Its Application to Surface Acoustic Wave on Acoustic Metamaterials

    NASA Astrophysics Data System (ADS)

    Shen, Jian Qi

    2016-08-01

    In a conventional formalism of acoustics, acoustic pressure p and velocity field u are used for characterizing acoustic waves propagating inside elastic/acoustic materials. We shall treat some fundamental problems relevant to acoustic wave propagation alternatively by using canonical acoustics (a more concise and compact formalism of acoustic dynamics), in which an acoustic scalar potential and an acoustic vector potential (Φ ,V), instead of the conventional acoustic field quantities such as acoustic pressure and velocity field (p,u) for characterizing acoustic waves, have been defined as the fundamental variables. The canonical formalism of the acoustic energy-momentum tensor is derived in terms of the acoustic potentials. Both the acoustic Hamiltonian density and the acoustic Lagrangian density have been defined, and based on this formulation, the acoustic wave quantization in a fluid is also developed. Such a formalism of acoustic potentials is employed to the problem of negative-mass-density assisted surface acoustic wave that is a highly localized surface bound state (an eigenstate of the acoustic wave equations). Since such a surface acoustic wave can be strongly confined to an interface between an acoustic metamaterial (e.g., fluid-solid composite structures with a negative dynamical mass density) and an ordinary material (with a positive mass density), it will give rise to an effect of acoustic field enhancement on the acoustic interface, and would have potential applications in acoustic device design for acoustic wave control.

  5. The Suppression of Dominant Acoustic Frequencies in MRI

    NASA Astrophysics Data System (ADS)

    Shou, Xingxian; Brown, Robert

    2011-03-01

    Patient discomfort and brain imaging distortion are serious MRI acoustic noise problems arising from the rapid switching on and off of gradient coils in the presence of the strong Larmor magnetic field. A study is made of dominant frequencies in the acoustic noise spectrum and, motivated by both spring and string ideas, we propose the cancellation of selected frequencies by appropriate gradient pulse sequence design. From both simulations and experiments, vibrations resulting from an impulsive force associated with a ramping up of a gradient pulse are shown to be cancelled upon the application of another impulsive force coming from the appropriately timed ramping down of that pulse. A method for the suppression of multiple-frequency contributions involving a series of gradient pulses with variable timings is developed and confirmed by experiment. Whether we refer to reduction in terms of dB (about 30-40 dB per peak), or to the verdict of a listener, the conclusion is that a marked reduction in sound can be achieved when at least three of the dominant frequency peaks are suppressed. A variety of pulse profiles and timing combinations can be used to attenuate important contributions to the acoustic spectrum. Supported by the Ohio Third Frontier Program.

  6. Acoustic Probe for Solid-Gas-Liquid Suspension

    SciTech Connect

    Tavlarides, L.L.; Sangani, Ashok

    2003-09-14

    The primary objective of the research project during the first funding period was to develop an acoustic probe to measure volume percent solids in solid-liquid slurries in the presence of small amounts of gas bubbles. This problem was addressed because of the great need for a non-invasive, accurate and reliable method for solids monitoring in liquid slurries in the presence of radiolytically generated gases throughout the DOE complex. These measurements are necessary during mobilization of salts and sediments in tanks, transport of these slurries in transfer lines to processing facilities across a site, and, in some instances, during high level waste processing. Although acoustic probes have been commonly used for monitoring flows in single-phase fluids (McLeod, 1967), their application to monitor two-phase mixtures has not yet fully realized its potential. A number of investigators in recent years have therefore been involved in developing probes for measuring the volume fractions in liquid solid suspensions (Atkinson and Kytomaa, 1993; Greenwood et al., 1993; Martin et al., 1995) and in liquid-liquid suspensions (Bonnet and Tavlarides, 1987; Tavlarides and Bonnet, 1988, Yi and Tavlarides, 1990; Tsouris and Tavlarides, 1993, Tsouris et al., 1995). In particular, Atkinson and Kytomaa (1993) showed that the acoustic technique can be used to determine both the velocity and the volume fraction of solids while Martin et al. (1995) and Spelt et al. (1999) showed that the acoustic probe can also be used to obtain information on the size distribution of the particles. In a recent testing of in-line slurry monitors with radioactive slurries suspended with Pulsair Mixers (Hylton & Bayne, 1999), an acoustic probe did not compare well with other instruments most probably due to presence of entrained gases and improper acoustic frequency range of interrogation. The work of the investigators cited has established the potential of the acoustic probe for characterizing

  7. The Relationship of Spiritual Beliefs and Involvement with the Experience of Anger and Stress in College Students

    ERIC Educational Resources Information Center

    Winterowd, Carrie; Harrist, Steve; Thomason, Nancy; Worth, Sheri; Carlozzi, Barbara

    2005-01-01

    The purpose of this study was to explore the relationship of spiritual beliefs and involvement with anger and stress in college students. The spirituality scales were positively related to perceived stress and most of the anger subscales. When stress was controlled, the spirituality subscales still contributed significantly to anger.

  8. Rural Schooling in Georgia: The Experiences of a Minority Community Service Organization Involved in Local School Decision-Making Activities

    ERIC Educational Resources Information Center

    Lowe, Cynthia Louise Altman

    2010-01-01

    This dissertation study was a descriptive case study of a minority community service organization whose members were actively involved in local school decision-making and activities in a rural Northeast Georgia community. Rural schools face unique challenges in light of current educational trends. To address the challenges, rural schools must…

  9. Mexican American Parents' Involvement in Adolescents' Peer Relationships: Exploring the Role of Culture and Adolescents' Peer Experiences

    ERIC Educational Resources Information Center

    Updegraff, Kimberly A.; Kim, Ji-Yeon; Killoren, Sarah E.; Thayer, Shawna M.

    2010-01-01

    This study examined the nature and correlates of Mexican American mothers' and fathers' involvement in adolescents' peer relationships along 4 dimensions: support, restriction, knowledge, and time spent with adolescents and peers. Mexican American adolescents and their parents in 220 families described their family relationships, cultural…

  10. Children's Well-Being and Involvement in Physically Active Outdoors Play in a Norwegian Kindergarten: Playful Sharing of Physical Experiences

    ERIC Educational Resources Information Center

    Bjørgen, Kathrine

    2015-01-01

    This qualitative study explores the conditions of children's level of well-being and their involvement in physically active play during kindergarten outdoors time. Observations of three to five year olds from one kindergarten in central Norway were conducted. The researcher followed the children around the kindergarten's outdoors playground and…

  11. Symptoms of Acoustic Neuroma

    MedlinePlus

    ... Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask Yourself ... Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask Yourself ...

  12. Acoustic optic hybrid (AOH) sensor

    PubMed

    Matthews; Arrieta

    2000-09-01

    The ability of laser vibrometers to receive and process acoustic echoes from the water surface above a submerged target is established and evaluated. Sonar echoes from a submerged target are collected from the water surface by a laser vibrometer. Feasibility of this approach to sensing underwater sound is demonstrated. If the acoustic excitation at an otherwise undisturbed water surface is 195 to 168 dB re: 1 microPa, signal-to-noise ratio (SNR), at the vibrometer output, is shown to range from about 46 to 6 dB. Capillary waves and gravity waves at the water surface are expected and shown to have some destructive effect on the process of echo retrieval. A series of experiments to quantify the surface wave effects is described. The wave experiment results are reported. A successful attempt to acquire echoes from a submerged target over a grid of points for further processing into a three-dimensional image is made and described. The data acquisition and beamforming techniques constitute a three-dimensional, acoustic optic, synthetic aperture sonar (SAS). Beamformed images are included. For an aircraft towing acoustic sensors through the water with a mechanical link, this technique holds the promise of increased safety and improved fuel efficiency. PMID:11008811

  13. Improved Calibration Of Acoustic Plethysmographic Sensors

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J.; Davis, David C.

    1993-01-01

    Improved method of calibration of acoustic plethysmographic sensors involves acoustic-impedance test conditions like those encountered in use. Clamped aluminum tube holds source of sound (hydrophone) inside balloon. Test and reference sensors attached to outside of balloon. Sensors used to measure blood flow, blood pressure, heart rate, breathing sounds, and other vital signs from surfaces of human bodies. Attached to torsos or limbs by straps or adhesives.

  14. Acoustic emission frequency discrimination

    NASA Technical Reports Server (NTRS)

    Sugg, Frank E. (Inventor); Graham, Lloyd J. (Inventor)

    1988-01-01

    In acoustic emission nondestructive testing, broadband frequency noise is distinguished from narrow banded acoustic emission signals, since the latter are valid events indicative of structural flaws in the material being examined. This is accomplished by separating out those signals which contain frequency components both within and beyond (either above or below) the range of valid acoustic emission events. Application to acoustic emission monitoring during nondestructive bond verification and proof loading of undensified tiles on the Space Shuttle Orbiter is considered.

  15. Acoustically-Induced Electrical Signals

    NASA Astrophysics Data System (ADS)

    Brown, S. R.

    2014-12-01

    We have observed electrical signals excited by and moving along with an acoustic pulse propagating in a sandstone sample. Using resonance we are now studying the characteristics of this acousto-electric signal and determining its origin and the controlling physical parameters. Four rock samples with a range of porosities, permeabilities, and mineralogies were chosen: Berea, Boise, and Colton sandstones and Austin Chalk. Pore water salinity was varied from deionized water to sea water. Ag-AgCl electrodes were attached to the sample and were interfaced to a 4-wire electrical resistivity system. Under computer control, the acoustic signals were excited and the electrical response was recorded. We see strong acoustically-induced electrical signals in all samples, with the magnitude of the effect for each rock getting stronger as we move from the 1st to the 3rd harmonics in resonance. Given a particular fluid salinity, each rock has its own distinct sensitivity in the induced electrical effect. For example at the 2nd harmonic, Berea Sandstone produces the largest electrical signal per acoustic power input even though Austin Chalk and Boise Sandstone tend to resonate with much larger amplitudes at the same harmonic. Two effects are potentially responsible for this acoustically-induced electrical response: one the co-seismic seismo-electric effect and the other a strain-induced resistivity change known as the acousto-electric effect. We have designed experimental tests to separate these mechanisms. The tests show that the seismo-electric effect is dominant in our studies. We note that these experiments are in a fluid viscosity dominated seismo-electric regime, leading to a simple interpretation of the signals where the electric potential developed is proportional to the local acceleration of the rock. Toward a test of this theory we have measured the local time-varying acoustic strain in our samples using a laser vibrometer.

  16. Nonlinear positron acoustic solitary waves

    SciTech Connect

    Tribeche, Mouloud; Aoutou, Kamel; Younsi, Smain; Amour, Rabia

    2009-07-15

    The problem of nonlinear positron acoustic solitary waves involving the dynamics of mobile cold positrons is addressed. A theoretical work is presented to show their existence and possible realization in a simple four-component plasma model. The results should be useful for the understanding of the localized structures that may occur in space and laboratory plasmas as new sources of cold positrons are now well developed.

  17. Tutorial on architectural acoustics

    NASA Astrophysics Data System (ADS)

    Shaw, Neil; Talaske, Rick; Bistafa, Sylvio

    2002-11-01

    This tutorial is intended to provide an overview of current knowledge and practice in architectural acoustics. Topics covered will include basic concepts and history, acoustics of small rooms (small rooms for speech such as classrooms and meeting rooms, music studios, small critical listening spaces such as home theatres) and the acoustics of large rooms (larger assembly halls, auditoria, and performance halls).

  18. Malignant Peritoneum Mesothelioma with Hepatic Involvement: A Single Institution Experience in 5 Patients and Review of the Literature

    PubMed Central

    Su, Shan-shan; Zheng, Guo-qi; Liu, Ya-gang; Chen, Yue-feng; Song, Zhao-wei; Yu, Shu-jing; Sun, Ning-ning; Yang, Yu-xin

    2016-01-01

    Malignant peritoneal mesothelioma with invasion of the liver is an invariably fatal disease. We aimed to clarify the characteristics of malignant peritoneal mesothelioma cases with liver involvement. The clinical presentation, computed tomography images, and immunohistochemical and histopathological features of 5 patients with malignant peritoneal mesothelioma and liver involvement were evaluated. The diagnosis was established by imaging and immune profiles of the tumours. A review of 8 cases with primary or invading malignant mesothelioma in liver is presented. All 5 mesothelioma cases were asbestos-related. CT images of malignant peritoneal mesothelioma with the liver involvement typically showed that the lesion grew inside the liver along the capsule and was possibly accompanied by capsule breakthrough and extrahepatic infiltration. The tumours exhibited a common epithelioid appearance in all 5 patients and most cases revealed positive Cal, CK, and MC with negative CEA and HeP. Different from our findings, the review of literature revealed that most malignant mesothelioma of liver was due to primary intrahepatic malignant mesothelioma. Finally, we concluded that the diagnosis of malignant peritoneal mesothelioma cases with liver invasion is reliably achieved by the history of asbestos exposure, the characteristic CT imaging, and immune profiles of the tumours. PMID:27069474

  19. 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.

  20. Classroom-to-Home Connections: Young Children's Experiences with a Technology-Based Parent Involvement Tool

    ERIC Educational Resources Information Center

    Walsh, Bridget A.; Cromer, Heidi; Weigel, Daniel J.

    2014-01-01

    Research Findings: DVD classroom newsletters are one proposed technology tool to promote classroom-to-home connections. The present study explored the experiences of prekindergarten children from predominantly Spanish-speaking homes with bilingual (English and Spanish) DVD classroom newsletters. On average, parents reported that children watched…

  1. Signal enhancement of J-HMQC experiments in solid-state NMR involving half-integer quadrupolar nuclei.

    PubMed

    Wang, Qiang; Trébosc, Julien; Li, Yixuan; Xu, Jun; Hu, Bingwen; Feng, Ningdong; Chen, Qun; Lafon, Oliver; Amoureux, Jean-Paul; Deng, Feng

    2013-07-28

    We show that for half-integer quadrupolar nuclei, the manipulation of the satellite transitions can accelerate and enhance coherence transfer to other isotopes. This novel strategy is demonstrated to improve the sensitivity of (31)P-{(27)Al} J-HMQC experiments for a layered aluminophosphate Mu-4. PMID:23770976

  2. 13-C NMR Spectra of Styrene Derivatives: An Undergraduate Experiment Involving the Application of the Hammett Equation.

    ERIC Educational Resources Information Center

    Blunt, J. W.; Happer, D. A. R.

    1979-01-01

    In this experiment, the observation that, for meta- and para-substituted styrene derivatives, the magnitude of the C-13 shielding value for the beta-carbon is linearly related to sigma for the ring substituent is used to determine sigma. (BB)

  3. Measuring the acoustic response of Helmholtz resonators

    NASA Astrophysics Data System (ADS)

    Monteiro, Martín; Marti, Arturo C.; Vogt, Patrik; Kasper, Lutz; Quarthal, Dominik

    2015-04-01

    Many experiments have been proposed to investigate acoustic phenomena in college and early undergraduate levels, in particular the speed of sound,1-9 by means of different methods, such as time of flight, transit time, or resonance in tubes. In this paper we propose to measure the acoustic response curves of a glass beaker filled with different gases, used as an acoustic resonator. We show that these curves expose many interesting peaks and features, one of which matches the resonance peak predicted for a Helmholtz resonator fairly well, and gives a decent estimate for the speed of sound in some cases. The measures are obtained thanks to the capabilities of smartphones.

  4. Modeling steady-state experiments with a scanning electrochemical microscope involving several independent diffusing species using the boundary element method.

    PubMed

    Sklyar, Oleg; Träuble, Markus; Zhao, Chuan; Wittstock, Gunther

    2006-08-17

    The BEM algorithm developed earlier for steady-state experiments in the scanning electrochemical microscopy (SECM) feedback mode has been expanded to allow for the treatment of more than one independently diffusing species. This allows the treatment of substrate-generation/tip-collection SECM experiments. The simulations revealed the interrelation of sample layout, local kinetics, imaging conditions, and the quality of the obtained SECM images. Resolution in the SECM SG/TC images has been evaluated, and it depends on several factors. For most practical situations, the resolution is limited by the diffusion profiles of the sample. When a dissolved compound is converted at the sample (e.g., oxygen reduction or enzymatic reaction at the sample), the working distance should be significantly larger than in SECM feedback experiments (ca. 3 r(T) for RG = 5) in order to avoid diffusional shielding of the active regions on the sample by the UME body. The resolution ability also depends on the kinetics of the active regions. The best resolution can be expected if all the active regions cause the same flux. In one simulated example, which might mimic a possible scenario of a low-density protein array, considerable compromises in the resolving power, were noted when the flux from two neighboring spots differs by more than a factor of 2. PMID:16898739

  5. Involvement of activated leukocytes in the regulation of plasma levels of acute phase proteins in microgravity simulation experiments

    NASA Astrophysics Data System (ADS)

    Larina, Olga; Bekker, Anna; Turin-Kuzmin, Alexey

    2016-07-01

    Earth-based studies of microgravity effects showed the induction of the mechanisms of acute phase reaction (APR). APR comprises the transition of stress-sensitive protein kinases of macrophages and other responsive cells into the active state and the phosphorylation of transcription factors which in turn stimulate the production of acute-phase reaction cytokines. Leukocyte activation is accompanied by the acceleration of the formation of oxygen radicals which can serve a functional indice of leukocyte cell state. The series of events at acute phase response result in selective changes in the synthesis of a number of secretory blood proteins (acute phase proteins, APPs) in liver cells thus contributing the recovery of homeostasis state in the organism. Earlier experiment with head-down tilt showed the increase in plasma concentrations of two cytokine mediators of acute phase response, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) being the outcome of the activation of producer cells, foremost, leukocytes. In experiment with 4-day dry immersion chemiluminescent (ChL) reply of the whole blood samples to a test stimulus were studied along with the measurements of plasma levels of APPs, namely, alpha1-antitrypsin (alpha1-AT), alpha1-acid glycoprotein (alpha1-AGP), alpha2-macroglobulin (alpha2-M), ceruloplasmin (Cer), haptoglobin (Hp), C3-complement component (C3), C-reactive protein (CRP). Eight individuals aged 21.2 ± 3.2 years were the test subjects in the investigation. Protein studies showed a noticeable increase in the mean plasma levels of all APPs measured in experiment thus producing the evidence of the activation of acute phase response mechanisms while individual patterns revealed variability during the immersion period. The overall trends were similar to these in the previous immersion series. The augment in the strength of signal in stimulated light emission tests was higher after 1- and 2-day of immersion exposure than before the

  6. Acoustic simulation in architecture with parallel algorithm

    NASA Astrophysics Data System (ADS)

    Li, Xiaohong; Zhang, Xinrong; Li, Dan

    2004-03-01

    In allusion to complexity of architecture environment and Real-time simulation of architecture acoustics, a parallel radiosity algorithm was developed. The distribution of sound energy in scene is solved with this method. And then the impulse response between sources and receivers at frequency segment, which are calculated with multi-process, are combined into whole frequency response. The numerical experiment shows that parallel arithmetic can improve the acoustic simulating efficiency of complex scene.

  7. Acoustic emission from composite materials. [nondestructive tests

    NASA Technical Reports Server (NTRS)

    Visconti, I. C.; Teti, R.

    1979-01-01

    The two basic areas where the acoustic emission (AE) technique can be applied are materials research and the evaluation of structural reliability. This experimental method leads to a better understanding of fracture mechanisms and is an NDT technique particularly well suited for the study of propagating cracks. Experiments are described in which acoustic emissions were unambiguously correlated with microstructural fracture mechanisms. The advantages and limitations of the AE technique are noted.

  8. 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.

  9. Computational and experimental techniques for coupled acoustic/structure interactions.

    SciTech Connect

    Sumali, Anton Hartono; Pierson, Kendall Hugh; Walsh, Timothy Francis; Dohner, Jeffrey Lynn; Reese, Garth M.; Day, David Minot

    2004-01-01

    This report documents the results obtained during a one-year Laboratory Directed Research and Development (LDRD) initiative aimed at investigating coupled structural acoustic interactions by means of algorithm development and experiment. Finite element acoustic formulations have been developed based on fluid velocity potential and fluid displacement. Domain decomposition and diagonal scaling preconditioners were investigated for parallel implementation. A formulation that includes fluid viscosity and that can simulate both pressure and shear waves in fluid was developed. An acoustic wave tube was built, tested, and shown to be an effective means of testing acoustic loading on simple test structures. The tube is capable of creating a semi-infinite acoustic field due to nonreflecting acoustic termination at one end. In addition, a micro-torsional disk was created and tested for the purposes of investigating acoustic shear wave damping in microstructures, and the slip boundary conditions that occur along the wet interface when the Knudsen number becomes sufficiently large.

  10. CORTICAL INVOLVEMENT IN THE STARTREACT EFFECT

    PubMed Central

    Stevenson, Andrew J. T.; Chiu, Chenhao; Maslovat, Dana; Chua, Romeo; Gick, Bryan; Blouin, Jean-Sébastien; Franks, Ian M.

    2014-01-01

    The rapid release of prepared movements by a loud acoustic stimulus capable of eliciting a startle response has been termed the StartReact effect (Valls-Solé et al., 1999), and premotor reaction times (PMTs) of <70 ms are often observed. Two explanations have been given for these short latency responses. The subcortical storage and triggering hypothesis suggests movements that can be prepared in advance of a “go” signal are stored and triggered from subcortical areas by a startling acoustic stimulus (SAS) without cortical involvement. Alternatively, it has been hypothesized that the SAS can trigger movements from cortical areas through a faster pathway ascending from subcortical structures. Two experiments were designed to examine the possible role of primary motor cortex in the StartReact effect. In Experiment 1, we used suprathreshold transcranial magnetic stimulation (TMS) during the reaction time (RT) interval to induce a cortical silent period in the contralateral primary motor cortex (M1). Thirteen participants performed 20° wrist extension movements as fast as possible in response to either a control stimulus (82dB) or SAS (124 dB). PMTs for startle trials were faster than control trials, while TMS significantly delayed movement onset compared to No TMS or Sham TMS conditions. In Experiment 2, we examined the StartReact effect in a highly cortically represented action involving speech of a consonant-vowel (CV) syllable. Similar to previous work examining limb movements, a robust StartReact effect was found. Collectively, these experiments provide evidence for cortical (M1) involvement in the StartReact effect. PMID:24680855

  11. Longitudinal bulk acoustic mass sensor

    SciTech Connect

    Hales, J. H.; Teva, J.; Boisen, A.; Davis, Z. J.

    2009-07-20

    A polycrystalline silicon longitudinal bulk acoustic cantilever is fabricated and operated in air at 51 MHz. A mass sensitivity of 100 Hz/fg (1 fg=10{sup -15} g) is obtained from the preliminary experiments where a minute mass is deposited on the device by means of focused ion beam. The total noise in the currently applied measurement system allows for a minimum detectable mass of 0.5 fg in air.

  12. Factors involved in growth plasticity of cockles Cerastoderma edule (L.), identified by field survey and transplant experiments

    NASA Astrophysics Data System (ADS)

    De Montaudouin, Xavier

    1996-12-01

    In Arcachon Bay, a macrotidal coastal lagoon in southwest France, growth rates of cockles Cerastoderma edule (L.) differ greatly between locations. Sampling of populations at different tidal levels showed that the mean shell length was significantly and positively correlated with immersion time, whereas no correlation was found with population density and microphytobenthos biomass. Transplants of cockles between two intertidal sites were used to examine the relative importance of habitat and site of origin for growth rate and condition index. Artifacts due to manipulation were assessed, i.e. the impact of enclosures on growth, conditon index and mortality. During a 5-mo reciprocal transplant experiment, growth rates of the transplanted cockles and the cockles already present were similar, whereas the sites of origin did not affect growth rate. Condition index, however, displayed significant differences in relation to both transplant and origin sites. During a further 6-mo experiment in which cockles were transplanted from one site to four new sites, growth was mainly influenced by tidal level. These results indicate that net growth started when cockles were immersed 30% of the time. It is concluded that, on the scale of Arcachon Bay (156 km 2), differences in growth and condition between cockle populations are largely phenotypic. Tidal level ( i.e. food supply and emersion stress) accounts for most of these differences, but the existence of genetically or physiologically different populations cannot be excluded.

  13. Collaboration and involvement of persons with lived experience in planning Canada's At Home/Chez Soi project.

    PubMed

    Nelson, Geoffrey; Macnaughton, Eric; Curwood, Susan Eckerle; Egalité, Nathalie; Voronka, Jijian; Fleury, Marie-Josée; Kirst, Maritt; Flowers, Linsay; Patterson, Michelle; Dudley, Michael; Piat, Myra; Goering, Paula

    2016-03-01

    Planning the implementation of evidence-based mental health services entails commitment to both rigour and community relevance, which entails navigating the challenges of collaboration between professionals and community members in a planning environment which is neither 'top-down' nor 'bottom-up'. This research focused on collaboration among different stakeholders (e.g. researchers, service-providers, persons with lived experience [PWLE]) at five project sites across Canada in the planning of At Home/Chez Soi, a Housing First initiative for homeless people with mental health problems. The research addressed the question of what strategies worked well or less well in achieving successful collaboration, given the opportunities and challenges within this complex 'hybrid' planning environment. Using qualitative methods, 131 local stakeholders participated in key informant or focus group interviews between October 2009 and February 2010. Site researchers identified themes in the data, using the constant comparative method. Strategies that enhanced collaboration included the development of a common vision, values and purpose around the Housing First approach, developing a sense of belonging and commitment among stakeholders, bridging strategies employed by Site Co-ordinators and multiple strategies to engage PWLE. At the same time, a tight timeline, initial tensions, questions and resistance regarding project and research parameters, and lack of experience in engaging PWLE challenged collaboration. In a hybrid planning environment, clear communication and specific strategies are required that flow from an understanding that the process is neither fully participatory nor expert-driven, but rather a hybrid of both. PMID:25689287

  14. Acoustic Attraction

    NASA Astrophysics Data System (ADS)

    Oviatt, Eric; Patsiaouris, Konstantinos; Denardo, Bruce

    2009-11-01

    A sound source of finite size produces a diverging traveling wave in an unbounded fluid. A rigid body that is small compared to the wavelength experiences an attractive radiation force (toward the source). An attractive force is also exerted on the fluid itself. The effect can be demonstrated with a styrofoam ball suspended near a loudspeaker that is producing sound of high amplitude and low frequency (for example, 100 Hz). The behavior can be understood and roughly calculated as a time-averaged Bernoulli effect. A rigorous scattering calculation yields a radiation force that is within a factor of two of the Bernoulli result. For a spherical wave, the force decreases as the inverse fifth power of the distance from the source. Applications of the phenomenon include ultrasonic filtration of liquids and the growth of supermassive black holes that emit sound waves in a surrounding plasma. An experiment is being conducted in an anechoic chamber with a 1-inch diameter aluminum ball that is suspended from an analytical balance. Directly below the ball is a baffled loudspeaker that exerts an attractive force that is measured by the balance.

  15. Acoustics of Fluid-Structure Interactions

    NASA Astrophysics Data System (ADS)

    Howe, M. S.

    1998-08-01

    Acoustics of Fluid-Structure Interactions addresses an increasingly important branch of fluid mechanics--the absorption of noise and vibration by fluid flow. This subject, which offers numerous challenges to conventional areas of acoustics, is of growing concern in places where the environment is adversely affected by sound. Howe presents useful background material on fluid mechanics and the elementary concepts of classical acoustics and structural vibrations. Using examples, many of which include complete worked solutions, he vividly illustrates the theoretical concepts involved. He provides the basis for all calculations necessary for the determination of sound generation by aircraft, ships, general ventilation and combustion systems, as well as musical instruments. Both a graduate textbook and a reference for researchers, Acoustics of Fluid-Structure Interactions is an important synthesis of information in this field. It will also aid engineers in the theory and practice of noise control.

  16. Decoding Group Vocalizations: The Acoustic Energy Distribution of Chorus Howls Is Useful to Determine Wolf Reproduction.

    PubMed

    Palacios, Vicente; López-Bao, José Vicente; Llaneza, Luis; Fernández, Carlos; Font, Enrique

    2016-01-01

    Population monitoring is crucial for wildlife management and conservation. In the last few decades, wildlife researchers have increasingly applied bioacoustics tools to obtain information on several essential ecological parameters, such as distribution and abundance. One such application involves wolves (Canis lupus). These canids respond to simulated howls by emitting group vocalizations known as chorus howls. These responses to simulated howls reveal the presence of wolf litters during the breeding period and are therefore often used to determine the status of wolf populations. However, the acoustic structure of chorus howls is complex and discriminating the presence of pups in a chorus is sometimes difficult, even for experienced observers. In this study, we evaluate the usefulness of analyses of the acoustic energy distribution in chorus howls to identify the presence of pups in a chorus. We analysed 110 Iberian wolf chorus howls with known pack composition and found that the acoustic energy distribution is concentrated at higher frequencies when there are pups vocalizing. We built predictive models using acoustic energy distribution features to determine the presence of pups in a chorus, concluding that the acoustic energy distribution in chorus howls can be used to determine the presence of wolf pups in a pack. The method we outline here is objective, accurate, easily implemented, and independent of the observer's experience. These advantages are especially relevant in the case of broad scale surveys or when many observers are involved. Furthermore, the analysis of the acoustic energy distribution can be implemented for monitoring other social canids that emit chorus howls such as jackals or coyotes, provides an easy way to obtain information on ecological parameters such as reproductive success, and could be useful to study other group vocalizations. PMID:27144887

  17. Decoding Group Vocalizations: The Acoustic Energy Distribution of Chorus Howls Is Useful to Determine Wolf Reproduction

    PubMed Central

    López-Bao, José Vicente; Llaneza, Luis; Fernández, Carlos; Font, Enrique

    2016-01-01

    Population monitoring is crucial for wildlife management and conservation. In the last few decades, wildlife researchers have increasingly applied bioacoustics tools to obtain information on several essential ecological parameters, such as distribution and abundance. One such application involves wolves (Canis lupus). These canids respond to simulated howls by emitting group vocalizations known as chorus howls. These responses to simulated howls reveal the presence of wolf litters during the breeding period and are therefore often used to determine the status of wolf populations. However, the acoustic structure of chorus howls is complex and discriminating the presence of pups in a chorus is sometimes difficult, even for experienced observers. In this study, we evaluate the usefulness of analyses of the acoustic energy distribution in chorus howls to identify the presence of pups in a chorus. We analysed 110 Iberian wolf chorus howls with known pack composition and found that the acoustic energy distribution is concentrated at higher frequencies when there are pups vocalizing. We built predictive models using acoustic energy distribution features to determine the presence of pups in a chorus, concluding that the acoustic energy distribution in chorus howls can be used to determine the presence of wolf pups in a pack. The method we outline here is objective, accurate, easily implemented, and independent of the observer's experience. These advantages are especially relevant in the case of broad scale surveys or when many observers are involved. Furthermore, the analysis of the acoustic energy distribution can be implemented for monitoring other social canids that emit chorus howls such as jackals or coyotes, provides an easy way to obtain information on ecological parameters such as reproductive success, and could be useful to study other group vocalizations. PMID:27144887

  18. Acoustic excitation: A promising new means of controlling shear layers

    NASA Technical Reports Server (NTRS)

    Stone, J. R.; Mckinzie, D. J., Jr.

    1984-01-01

    Techniques have long been sought for the controlled modification of turbulent shear layers, such as in jets, wakes, boundary layers, and separated flows. Relatively recently published results of laboratory experiments have established that coherent structures exist within turbulent flows. These results indicate that even apparently chaotic flow fields can contain deterministic, nonrandom elements. Even more recently published results show that deliberate acoustic excitation of these coherent structures has a significant effect on the mixing characteristics of shear layers. Therefore, we have initiated a research effort to develop both an understanding of the interaction mechanisms and the ability to use it to favorably modify various shear layers. Acoustic excitation circumvents the need for pumping significant flow rates, as required by suction or blowing. Control of flows by intentional excitation of natural flow instabilities involves new and largely unexplored phenomena and offers considerable potential for improving component performance. Nonintrusive techniques for flow field control may permit much more efficient, flexible propulsion systems and aircraft designs, including means of stall avoidance and recovery. The techniques developed may also find application in many other areas where mixing is important, such as reactors, continuous lasers, rocket engines, and fluidic devices. It is the objective of this paper to examine some potential applications of the acoustic excitation technique to various shear layer flows of practical aerospace systems.

  19. Acoustic mapping of ocean currents using networked distributed sensors.

    PubMed

    Huang, Chen-Fen; Yang, T C; Liu, Jin-Yuan; Schindall, Jeff

    2013-09-01

    Distributed underwater sensors are expected to provide oceanographic monitoring over large areas. As fabrication technology advances, low cost sensors will be available for many uses. The sensors communicate to each other and are networked using acoustic communications. This paper first studies the performance of such systems for current measurements using tomographic inversion approaches to compare with that of a conventional system which distributes the sensors on the periphery of the area of interest. It then proposes two simple signal processing methods for ocean current mapping (using distributed networked sensors) aimed at real-time in-buoy processing. Tomographic inversion generally requires solving a challenging high dimensional inverse problem, involving substantial computations. Given distributed sensors, currents can be constructed locally based on data from neighboring sensors. It is shown using simulated data that similar results are obtained using distributed processing as using conventional tomographic approaches. The advantage for distributed systems is that by increasing the number of nodes, one gains a much more improved performance. Furthermore, distributed systems use much less energy than a conventional tomographic system for the same area coverage. Experimental data from an acoustic communication and networking experiment are used to demonstrate the feasibility of acoustic current mapping. PMID:23967940

  20. Acoustic Characterization of Compact Jet Engine Simulator Units

    NASA Technical Reports Server (NTRS)

    Doty, Michael J.; Haskin, Henry H.

    2013-01-01

    Two dual-stream, heated jet, Compact Jet Engine Simulator (CJES) units are designed for wind tunnel acoustic experiments involving a Hybrid Wing Body (HWB) vehicle. The newly fabricated CJES units are characterized with a series of acoustic and flowfield investigations to ensure successful operation with minimal rig noise. To limit simulator size, consistent with a 5.8% HWB model, the CJES units adapt Ultra Compact Combustor (UCC) technology developed at the Air Force Research Laboratory. Stable and controllable operation of the combustor is demonstrated using passive swirl air injection and backpressuring of the combustion chamber. Combustion instability tones are eliminated using nonuniform flow conditioners in conjunction with upstream screens. Through proper flow conditioning, rig noise is reduced by more than 20 dB over a broad spectral range, but it is not completely eliminated at high frequencies. The low-noise chevron nozzle concept designed for the HWB test shows expected acoustic benefits when installed on the CJES unit, and consistency between CJES units is shown to be within 0.5 dB OASPL.

  1. Acoustic sensor networks for woodpecker localization

    NASA Astrophysics Data System (ADS)

    Wang, H.; Chen, C. E.; Ali, A.; Asgari, S.; Hudson, R. E.; Yao, K.; Estrin, D.; Taylor, C.

    2005-08-01

    Sensor network technology can revolutionize the study of animal ecology by providing a means of non-intrusive, simultaneous monitoring of interaction among multiple animals. In this paper, we investigate design, analysis, and testing of acoustic arrays for localizing acorn woodpeckers using their vocalizations. Each acoustic array consists of four microphones arranged in a square. All four audio channels within the same acoustic array are finely synchronized within a few micro seconds. We apply the approximate maximum likelihood (AML) method to synchronized audio channels of each acoustic array for estimating the direction-of-arrival (DOA) of woodpecker vocalizations. The woodpecker location is estimated by applying least square (LS) methods to DOA bearing crossings of multiple acoustic arrays. We have revealed the critical relation between microphone spacing of acoustic arrays and robustness of beamforming of woodpecker vocalizations. Woodpecker localization experiments using robust array element spacing in different types of environments are conducted and compared. Practical issues about calibration of acoustic array orientation are also discussed.

  2. 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.

  3. Involving stakeholders in the commissioning and implementation of fishery science projects: experiences from the U.K. Fisheries Science Partnership.

    PubMed

    Armstrong, M J; Payne, A I L; Deas, B; Catchpole, T L

    2013-10-01

    Following from similar initiatives worldwide, the U.K.'s Fisheries Science Partnership (FSP) was established in 2003 to provide the fishing industry with opportunities to propose and participate in scientific studies in collaboration with fishery scientists. Key concepts were that most of the available funding would support industry participation, that industry, not scientists, would come up with the ideas for projects, and that commercial fishing vessels and fishing methods would be used to address specific concerns of the fishing industry in a scientifically controlled manner. Nearly 100 projects had been commissioned by March 2012, covering annual time-series surveys of stocks subject to traditional assessment, and ad hoc projects on, e.g. gear selectivity, discard survival, tagging and migration and fishery development. The extent to which the results of the projects have been used by stakeholders, fishery scientists and fishery managers at a national and E.U. level is evaluated, along with the degree of industry interest and involvement, and reasons are identified for successes or failures in the uptake of the results into management and policy. Finally, the question is posed whether the programme has been successful in improving the engagement of the fishing community in the science-management process and in fostering communication and greater trust between fishers, scientists and managers. PMID:24090558

  4. 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.

  5. 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.

  6. Study Acoustic Emissions from Composites

    NASA Technical Reports Server (NTRS)

    Walker, James L.; Workman, Gary L.

    1997-01-01

    The nondestructive evaluation (NDE) of future propulsion systems utilizing advanced composite structures for the storage of cryogenic fuels, such as liquid hydrogen or oxygen, presents many challenges. Economic justification for these structures requires, light weight, reusable components with an infrastructure allowing periodic evaluation of structural integrity after enduring demanding stresses during operation. A major focus has been placed on the use of acoustic emission NDE to detect propagating defects, in service, necessitating an extensive study into characterizing the nature of acoustic signal propagation at very low temperatures and developing the methodology of applying AE sensors to monitor cryogenic components. This work addresses the question of sensor performance in the cryogenic environment. Problems involving sensor mounting, spectral response and durability are addressed. The results of this work provides a common point of measure from which sensor selection can be made when testing composite components at cryogenic temperatures.

  7. Limitations of the acoustic approximation for seismic crosshole tomography

    NASA Astrophysics Data System (ADS)

    Marelli, Stefano; Maurer, Hansruedi

    2010-05-01

    implemented by setting the shear wave velocity to almost zero (Vs ~ 0). This approach was checked against a purely acoustic 2D pseudo-spectral time-domain modelling code and found to yield very similar results. In a variety of numerical 2D and 3D experiments, we propagated both acoustic only and full elastic waves through models of increasing complexity. We first investigated three basic simple-shaped anomalies embedded in a homogeneous background, including i) a vertical layer ii) a horizontal layer and iii) two-rectangular blocks. Maximum velocity contrast in these models is about 50% We then tested a more complex model representing a realistic-scale, engineered-nuclear waste repository-like structure, embedded in a granite host rock. Velocity contrasts were chosen to be much higher in this model. Our results indicate that for the simplest models (horizontal and vertical layers) the acoustic approximation is reasonable for the early portions of the seismograms, but for even only moderately complex subsurface models involving several interfaces (e.g. the two block anomalies), the acoustic approximation breaks down and fails to account for the synthesised wavefields. We attribute this failure to the presence of significant P-to-S mode conversions at each interface. Comparable observations were found for both the 2D and the 3D simulations. The main advantage of seismic waveform inversion is that subtle changes in amplitude and phase of the waveforms can be exploited for constructing subsurface models at sub-wavelength resolution. The significant deficiencies of the acoustic approximation for crosshole problems, even in the presence of relatively minor anomalies, therefore strongly question the usefulness of acoustic waveform transmission tomography. Consequently, efforts have to be made to implement the computationally much more challenging elastic waveform inversion scheme.

  8. HIV-Positive Men's Experiences with Integrated Family Planning and HIV Services in Western Kenya: Integration Fosters Male Involvement

    PubMed Central

    Baum, Sarah; Grossman, Daniel; Steinfeld, Rachel; Onono, Maricianah; Cohen, Craig; Bukusi, Elizabeth; Newmann, Sara

    2014-01-01

    Abstract A growing body of evidence indicates that integrating family planning (FP) services into HIV care is effective at improving contraceptive uptake among HIV-positive women in resource-poor settings, yet little research has examined HIV-positive men's experiences with such integration. We conducted in-depth interviews with 21 HIV-positive men seeking care at HIV clinics in Nyanza, Kenya. All clinics were intervention sites for a FP/HIV service integration cluster-randomized trial. Grounded theory was used to code and analyze the data. Our findings highlight men's motivations for FP, reasons why men prefer obtaining their FP services, which include education, counseling, and commodities, at HIV care clinics, and specific ways in which integrated FP/HIV services fostered male inclusion in FP decision-making. In conclusion, men appear invested in FP and their inclusion in FP decision-making may bolster both female and male agency. Men's positive attitudes towards FP being provided at HIV care clinics supports the programmatic push towards integrated delivery models for FP and HIV services. PMID:24927494

  9. HIV-positive men's experiences with integrated family planning and HIV services in western Kenya: integration fosters male involvement.

    PubMed

    Patel, Rena; Baum, Sarah; Grossman, Daniel; Steinfeld, Rachel; Onono, Maricianah; Cohen, Craig; Bukusi, Elizabeth; Newmann, Sara

    2014-08-01

    A growing body of evidence indicates that integrating family planning (FP) services into HIV care is effective at improving contraceptive uptake among HIV-positive women in resource-poor settings, yet little research has examined HIV-positive men's experiences with such integration. We conducted in-depth interviews with 21 HIV-positive men seeking care at HIV clinics in Nyanza, Kenya. All clinics were intervention sites for a FP/HIV service integration cluster-randomized trial. Grounded theory was used to code and analyze the data. Our findings highlight men's motivations for FP, reasons why men prefer obtaining their FP services, which include education, counseling, and commodities, at HIV care clinics, and specific ways in which integrated FP/HIV services fostered male inclusion in FP decision-making. In conclusion, men appear invested in FP and their inclusion in FP decision-making may bolster both female and male agency. Men's positive attitudes towards FP being provided at HIV care clinics supports the programmatic push towards integrated delivery models for FP and HIV services. PMID:24927494

  10. Acoustic Microfluidics for Bioanalytical Application

    NASA Astrophysics Data System (ADS)

    Lopez, Gabriel

    2013-03-01

    This talk will present new methods the use of ultrasonic standing waves in microfluidic systems to manipulate microparticles for the purpose of bioassays and bioseparations. We have recently developed multi-node acoustic focusing flow cells that can position particles into many parallel flow streams and have demonstrated the potential of such flow cells in the development of high throughput, parallel flow cytometers. These experiments show the potential for the creation of high throughput flow cytometers in applications requiring high flow rates and rapid detection of rare cells. This talk will also present the development of elastomeric capture microparticles and their use in acoustophoretic separations. We have developed simple methods to form elastomeric particles that are surface functionalized with biomolecular recognition reagents. These compressible particles exhibit negative acoustic contrast in ultrasound when suspended in aqueous media, blood serum or diluted blood. These particles can be continuously separated from cells by flowing them through a microfluidic device that uses an ultrasonic standing wave to align the blood cells, which exhibit positive acoustic contrast, at a node in the acoustic pressure distribution while aligning the negative acoustic contrast elastomeric particles at the antinodes. Laminar flow of the separated particles to downstream collection ports allows for collection of the separated negative contrast particles and cells. Separated elastomeric particles were analyzed via flow cytometry to demonstrate nanomolar detection for prostate specific antigen in aqueous buffer and picomolar detection for IgG in plasma and diluted blood samples. This approach has potential applications in the development of rapid assays that detect the presence of low concentrations of biomarkers (including biomolecules and cells) in a number of biological sample types. We acknowledge support through the NSF Research Triangle MRSEC.

  11. Involving lay community researchers in epidemiological research: experiences from a seroprevalence study among sub-Saharan African migrants

    PubMed Central

    Nöstlinger, Christiana; Loos, Jasna

    2016-01-01

    ABSTRACT Community-based participatory research (CBPR) has received considerable attention during past decades as a method to increase community ownership in research and prevention. We discuss its application to epidemiological research using the case of second-generation surveillance conducted among sub-Saharan African (SSA) migrants in Antwerp city. To inform evidence-based prevention planning for this target group, this HIV-prevalence study used two-stage time-location sampling preceded by formative research. Extensive collaborative partnerships were built with community organizations, a Community Advisory Board provided input throughout the project, and community researchers were trained to participate in all phases of the seroprevalence study. Valid oral fluid samples for HIV testing were collected among 717 SSA migrants and linked to behavioural data assessed through an anonymous survey between December 2013 and August 2014. A qualitative content analysis of various data sources (extensive field notes, minutes of intervision, and training protocols) collected at 77 data collection visits in 51 settings was carried out to describe experiences with challenges and opportunities inherent to the CBPR approach at three crucial stages of the research process: building collaborative partnerships; implementing the study; dissemination of findings including prevention planning. The results show that CBPR is feasible in conducting scientifically sound epidemiological research, but certain requirements need to be in place. These include among others sufficient resources to train, coordinate, and supervise community researchers; continuity in the implementation; transparency about decision-taking and administrative procedures, and willingness to share power and control over the full research process. CBPR contributed to empowering community researchers on a personal level, and to create greater HIV prevention demand in the SSA communities. PMID:26885938

  12. Involving lay community researchers in epidemiological research: experiences from a seroprevalence study among sub-Saharan African migrants.

    PubMed

    Nöstlinger, Christiana; Loos, Jasna

    2016-01-01

    Community-based participatory research (CBPR) has received considerable attention during past decades as a method to increase community ownership in research and prevention. We discuss its application to epidemiological research using the case of second-generation surveillance conducted among sub-Saharan African (SSA) migrants in Antwerp city. To inform evidence-based prevention planning for this target group, this HIV-prevalence study used two-stage time-location sampling preceded by formative research. Extensive collaborative partnerships were built with community organizations, a Community Advisory Board provided input throughout the project, and community researchers were trained to participate in all phases of the seroprevalence study. Valid oral fluid samples for HIV testing were collected among 717 SSA migrants and linked to behavioural data assessed through an anonymous survey between December 2013 and August 2014. A qualitative content analysis of various data sources (extensive field notes, minutes of intervision, and training protocols) collected at 77 data collection visits in 51 settings was carried out to describe experiences with challenges and opportunities inherent to the CBPR approach at three crucial stages of the research process: building collaborative partnerships; implementing the study; dissemination of findings including prevention planning. The results show that CBPR is feasible in conducting scientifically sound epidemiological research, but certain requirements need to be in place. These include among others sufficient resources to train, coordinate, and supervise community researchers; continuity in the implementation; transparency about decision-taking and administrative procedures, and willingness to share power and control over the full research process. CBPR contributed to empowering community researchers on a personal level, and to create greater HIV prevention demand in the SSA communities. PMID:26885938

  13. Acoustics for Music Majors-- A Laboratory Course

    ERIC Educational Resources Information Center

    McDonald, Perry F.

    1972-01-01

    Brief descriptions of several of the laboratory experiments which have been incorporated into an acoustics course for music majors. Includes vibratory motion and sound generation, nature, speed, and pitch of sound, spectrum analysis and electronic synthesis of musical sound and some conventional sound experiments. (Author/TS)

  14. Effect of acoustic field parameters on arc acoustic binding during ultrasonic wave-assisted arc welding.

    PubMed

    Xie, Weifeng; Fan, Chenglei; Yang, Chunli; Lin, Sanbao

    2016-03-01

    As a newly developed arc welding method, power ultrasound has been successfully introduced into arc and weld pool during ultrasonic wave-assisted arc welding process. The advanced process for molten metals can be realized by utilizing additional ultrasonic field. Under the action of the acoustic wave, the plasma arc as weld heat source is regulated and its characteristics make an obvious change. Compared with the conventional arc, the ultrasonic wave-assisted arc plasma is bound significantly and becomes brighter. To reveal the dependence of the acoustic binding force on acoustic field parameters, a two-dimensional acoustic field model for ultrasonic wave-assisted arc welding device is established. The influences of the radiator height, the central pore radius, the radiator radius, and curvature radius or depth of concave radiator surface are discussed using the boundary element method. Then the authors analyze the resonant mode by this relationship curve between acoustic radiation power and radiator height. Furthermore, the best acoustic binding ability is obtained by optimizing the geometric parameters of acoustic radiator. In addition, three concave radiator surfaces including spherical cap surface, paraboloid of revolution, and rotating single curved surface are investigated systematically. Finally, both the calculation and experiment suggest that, to obtain the best acoustic binding ability, the ultrasonic wave-assisted arc welding setup should be operated under the first resonant mode using a radiator with a spherical cap surface, a small central pore, a large section radius and an appropriate curvature radius. PMID:26558995

  15. 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.

  16. 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.

  17. Drag Measurements of Porous Plate Acoustic Liners

    NASA Technical Reports Server (NTRS)

    Wolter, John D.

    2005-01-01

    This paper presents the results of direct drag measurements on a variety of porous plate acoustic liners. The existing literature describes numerous studies of drag on porous walls with injection or suction, but relatively few of drag on porous plates with neither injection nor suction. Furthermore, the porosity of the porous plate in existing studies is much lower than typically used in acoustic liners. In the present work, the acoustic liners consisted of a perforated face sheet covering a bulk acoustic absorber material. Factors that were varied in the experiment were hole diameter, hole pattern, face sheet thickness, bulk material type, and size of the gap (if any) between the face sheet and the absorber material.

  18. A numerical model of acoustic choking. II - Shocked solutions

    NASA Astrophysics Data System (ADS)

    Walkington, N. J.; Eversman, W.

    1986-01-01

    The one dimensional equations of gas dynamics are used to model subsonic acoustic choking. This model can accommodate non-linear distortion of waves and the eventual formation of shock waves. Several finite differencing schemes are adapted to obtain solutions. The results obtained with the various schemes are compared with the asymptotic results available. The results suggest that no one finite differencing scheme gives solutions significantly better than the others and that most of the difference solutions are close to the asymptotic results. If the acoustic shock wave is sufficiently strong it almost annihilates the acoustic wave; in this situation numerical errors may dominate the results. Such solutions involve very large acoustic attenuations.

  19. Localized acoustic surface modes

    NASA Astrophysics Data System (ADS)

    Farhat, Mohamed; Chen, Pai-Yen; Bağcı, Hakan

    2016-04-01

    We introduce the concept of localized acoustic surface modes. We demonstrate that they are induced on a two-dimensional cylindrical rigid surface with subwavelength corrugations under excitation by an incident acoustic plane wave. Our results show that the corrugated rigid surface is acoustically equivalent to a cylindrical scatterer with uniform mass density that can be represented using a Drude-like model. This, indeed, suggests that plasmonic-like acoustic materials can be engineered with potential applications in various areas including sensing, imaging, and cloaking.

  20. Low frequency acoustic microscope

    DOEpatents

    Khuri-Yakub, Butrus T.

    1986-11-04

    A scanning acoustic microscope is disclosed for the detection and location of near surface flaws, inclusions or voids in a solid sample material. A focused beam of acoustic energy is directed at the sample with its focal plane at the subsurface flaw, inclusion or void location. The sample is scanned with the beam. Detected acoustic energy specularly reflected and mode converted at the surface of the sample and acoustic energy reflected by subsurface flaws, inclusions or voids at the focal plane are used for generating an interference signal which is processed and forms a signal indicative of the subsurface flaws, inclusions or voids.

  1. Acoustic dispersive prism.

    PubMed

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  2. Acoustic dispersive prism

    PubMed Central

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz–1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  3. Acoustic dispersive prism

    NASA Astrophysics Data System (ADS)

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium.

  4. Properties of the Acoustic Vector Field in Underwater Waveguides

    NASA Astrophysics Data System (ADS)

    Dall'Osto, David R.

    This thesis focuses on the description and measurement of the underwater acoustic field, based on vector properties of acoustic particle velocity. The specific goal is to interpret vector sensor measurements in underwater waveguides, in particular those measurements made in littoral (shallow) waters. To that end, theoretical models, which include the effects of reflections from the waveguide boundaries, are developed for the acoustic intensity, i.e. the product of acoustic pressure and acoustic particle velocity. Vector properties of acoustic intensity are shown to correspond to a non-dimensional vector property of acoustic particle velocity, its degree of circularity, which describes the trajectory of particle motion. Both experimental measurements and simulations of this non-dimensional vector property are used to analyze characteristics of sound propagation in underwater waveguides. Two measurement techniques are utilized in the experiments described in this thesis. In the first, particle velocity is obtained indirectly by time integration of the measured pressure gradient between two closely spaced (with respect to an acoustic wavelength) conventional pressure sensitive hydrophones. This method was used in ocean experiments conducted with vertical line arrays of hydrophones. In the second technique, particle velocity is measured directly by time integration of the signal generated by an accelerometer. An additional pressure measurement from a co-located hydrophone forms what is known as a "combined sensor" in the Russian literature, which allows for estimation of the vector acoustic intensity. This method was utilized mainly in laboratory experiments.

  5. Acoustically driven arrayed waveguide grating.

    PubMed

    Crespo-Poveda, A; Hernández-Mínguez, A; Gargallo, B; Biermann, K; Tahraoui, A; Santos, P V; Muñoz, P; Cantarero, A; de Lima, M M

    2015-08-10

    We demonstrate compact tunable phased-array wavelength-division multiplexers driven by surface acoustic waves (SAWs) in the low GHz range. The devices comprise two couplers, which respectively split and combine the optical signal, linked by an array of single-mode waveguides (WGs). Two different layouts are presented, in which multi-mode interference couplers or free propagating regions were separately employed as couplers. The multiplexers operate on five equally distributed wavelength channels, with a spectral separation of 2 nm. A standing SAW modulates the refractive index of the arrayed WGs. Each wavelength component periodically switches paths between the output channel previously asigned by the design and the adjacent channels, at a fixed applied acoustic power. The devices were monolithically fabricated on (Al,Ga)As. A good agreement between theory and experiment is achieved. PMID:26367971

  6. Spurious resonance suppression in gigahertz-range ZnO thin-film bulk acoustic wave resonators by the boundary frame method: modeling and experiment.

    PubMed

    Pensala, Tuomas; Ylilammi, Markku

    2009-08-01

    Zinc-oxide-based thin-film bulk acoustic wave (BAW) resonators operating at 932 MHz are investigated with respect to variation of dimensions of a boundary frame spurious mode suppression structure. A plate wave dispersion-based semi-2-D model and a 2-D finite element method are used to predict the eigenmode spectrum of the resonators to explain the detailed behavior. The models show how the boundary frame method changes the eigenmodes and their coupling to the driving electrical field via the modification of the mechanical boundary condition and leads to emergence of a flat-amplitude piston mode and suppression of spurious modes. Narrow band suppression of a single mode with a nonoptimal boundary frame is observed. Reduction of the effective electromechanical coupling coefficient k2eff as a function of the boundary width is observed and predicted by both models. The simple semi-2-D plate model is shown to predict the device behavior very well, and the 2-D finite element method results are shown to coincide with them with some additional effects. Breaking the resonator behavior down to eigenmodes, which are not directly observable in measurements, by the models, yields insight into the physics of the device operation. PMID:19686989

  7. Disclosure of HIV status: experiences and perceptions of persons living with HIV/AIDS and nurses involved in their care in Africa.

    PubMed

    Greeff, Minrie; Phetlhu, Rene; Makoae, Lucia N; Dlamini, Priscilla S; Holzemer, William L; Naidoo, Joanne R; Kohi, Thecla W; Uys, Leana R; Chirwa, Maureen L

    2008-03-01

    Most people with HIV have disclosed their status to someone, often with mixed results. Most health literature seems to favor disclosure by persons living with acquired immunodeficiency syndrome (AIDS), but it could be that to disclose is not always a good thing. We used a descriptive, qualitative research design to explore the experience of human immunodeficiency virus (HIV) and AIDS stigma of people living with HIV or AIDS and nurses involved in their care in Africa. Focus group discussions were held with respondents. We asked them to relate incidents that they themselves observed, and those that they themselves experienced in the community and in families. Thirty-nine focus groups were conducted in five countries in both urban and rural settings. This article is limited to a discussion of data related to the theme of disclosure only. The sub-themes of disclosure were experiences before the disclosure, the process of disclosure, and responses during and after disclosure. PMID:18235155

  8. Pattern-formation under acoustic driving forces

    NASA Astrophysics Data System (ADS)

    Valverde, Jose Manuel

    2015-07-01

    Chemical and metallurgical processes enhanced by high intensity acoustic waves, thermoacoustic engines and refrigerators, fuel rods in nuclear reactors, heat exchanger tubes, offshore and vibrating structures, solar thermal collectors, acoustic levitators, microfluidic devices, cycling, musical acoustics, blood flow through veins/arteries, hearing in the mammalian ear, carbon nanotube loudspeakers, etc. The evolution of a myriad of processes involving the oscillation of viscous fluids in the presence of solid boundaries is up to a certain extent influenced by acoustic streaming. In addition to the sound field, viscous energy dissipation at the fluid-solid boundary causes a time-independent fluid circulation, which can lead to a significant enhancement of heat, mass and momentum transfer at large oscillation amplitudes. A particularly relevant phenomenon that can be notably affected by acoustic streaming is the promotion of sound waves by temperature gradients or viceversa (thermoacoustics), which is at the basis of potentially efficient and environmental friendly engines and refrigerators that have attracted a renewed interest in the last years. In the present manuscript, historical developments and the underlying basic physics behind acoustic streaming and thermoacoustics are reviewed from an unifying perspective.

  9. On the thermo-acoustic Fant equation

    NASA Astrophysics Data System (ADS)

    Murray, P. R.; Howe, M. S.

    2012-07-01

    A 'reduced complexity' equation is derived to investigate combustion instabilities of a Rijke burner. The equation is nonlinear and furnishes limit cycle solutions for finite amplitude burner modes. It is a generalisation to combustion flows of the Fant equation used to investigate the production of voiced speech by unsteady throttling of flow by the vocal folds [G. Fant, Acoustic Theory of Speech Production. Mouton, The Hague, 1960]. In the thermo-acoustic problem the throttling occurs at the flame holder. The Fant equation governs the unsteady volume flow past the flame holder which, in turn, determines the acoustics of the entire system. The equation includes a fully determinate part that depends on the geometry of the flame holder and the thermo-acoustic system, and terms defined by integrals involving thermo-aerodynamic sources, such as a flame and vortex sound sources. These integrals provide a clear indication of what must be known about the flow to obtain a proper understanding of the dynamics of the thermo-acoustic system. Illustrative numerical results are presented for the linearised equation. This governs the growth rates of the natural acoustic modes, determined by system geometry, boundary conditions and mean temperature distribution, which are excited into instability by unsteady heat release from the flame and damped by large scale vorticity production and radiation losses into the environment. In addition, the equation supplies information about the 'combustion modes' excited by the local time-delay feedback dynamics of the flame.

  10. Early visual experience and the recognition of basic facial expressions: involvement of the middle temporal and inferior frontal gyri during haptic identification by the early blind.

    PubMed

    Kitada, Ryo; Okamoto, Yuko; Sasaki, Akihiro T; Kochiyama, Takanori; Miyahara, Motohide; Lederman, Susan J; Sadato, Norihiro

    2013-01-01

    Face perception is critical for social communication. Given its fundamental importance in the course of evolution, the innate neural mechanisms can anticipate the computations necessary for representing faces. However, the effect of visual deprivation on the formation of neural mechanisms that underlie face perception is largely unknown. We previously showed that sighted individuals can recognize basic facial expressions by haptics surprisingly well. Moreover, the inferior frontal gyrus (IFG) and posterior superior temporal sulcus (pSTS) in the sighted subjects are involved in haptic and visual recognition of facial expressions. Here, we conducted both psychophysical and functional magnetic-resonance imaging (fMRI) experiments to determine the nature of the neural representation that subserves the recognition of basic facial expressions in early blind individuals. In a psychophysical experiment, both early blind and sighted subjects haptically identified basic facial expressions at levels well above chance. In the subsequent fMRI experiment, both groups haptically identified facial expressions and shoe types (control). The sighted subjects then completed the same task visually. Within brain regions activated by the visual and haptic identification of facial expressions (relative to that of shoes) in the sighted group, corresponding haptic identification in the early blind activated regions in the inferior frontal and middle temporal gyri. These results suggest that the neural system that underlies the recognition of basic facial expressions develops supramodally even in the absence of early visual experience. PMID:23372547

  11. Acoustics Critical Readiness Review

    NASA Technical Reports Server (NTRS)

    Ballard, Kenny

    2010-01-01

    This presentation reviews the status of the acoustic equipment from the medical operations perspective. Included is information about the acoustic dosimeters, sound level meter, and headphones that are planned for use while on orbit. Finally there is information about on-orbit hearing assessments.

  12. The challenge of acoustics

    NASA Astrophysics Data System (ADS)

    Lord, P.

    1981-01-01

    The various applications of acoustics, including sonar, ultrasonic examination of unborn foetuses and architectural applications, are briefly reviewed. Problems in traffic and industrial noise, auditorium design and explosive noise are considered in more detail. The educational aspects of acoustical science and technology are briefly considered.

  13. An acoustic emission study of plastic deformation in polycrystalline aluminium

    NASA Technical Reports Server (NTRS)

    Bill, R. C.; Frederick, J. R.; Felbeck, D. K.

    1979-01-01

    Acoustic emission experiments were performed on polycrystalline and single crystal 99.99% aluminum while undergoing tensile deformation. It was found that acoustic emission counts as a function of grain size showed a maximum value at a particular grain size. Furthermore, the slip area associated with this particular grain size corresponded to the threshold level of detectability of single dislocation slip events. The rate of decline in acoustic emission activity as grain size is increased beyond the peak value suggests that grain boundary associated dislocation sources are giving rise to the bulk of the detected acoustic emissions.

  14. Tiltrotor Acoustic Flight Test: Terminal Area Operations

    NASA Technical Reports Server (NTRS)

    SantaMaria, O. L.; Wellman, J. B.; Conner, D. A.; Rutledge, C. K.

    1991-01-01

    This paper provides a comprehensive description of an acoustic flight test of the XV- 15 Tiltrotor Aircraft with Advanced Technology Blades (ATB) conducted in August and September 1991 at Crows Landing, California. The purpose of this cooperative research effort of the NASA Langley and Ames Research Centers was to obtain a preliminary, high quality database of far-field acoustics for terminal area operations of the XV-15 at a takeoff gross weight of approximately 14,000 lbs for various glide slopes, airspeeds, rotor tip speeds, and nacelle tilt angles. The test also was used to assess the suitability of the Crows Landing complex for full scale far-field acoustic testing. This was the first acoustic flight test of the XV-15 aircraft equipped with ATB involving approach and level flyover operations. The test involved coordination of numerous personnel, facilities and equipment. Considerable effort was made to minimize potential extraneous noise sources unique to the region during the test. Acoustic data from the level flyovers were analyzed, then compared with data from a previous test of the XV-15 equipped with Standard Metal Blades

  15. 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

  16. Ocean acoustic hurricane classification.

    PubMed

    Wilson, Joshua D; Makris, Nicholas C

    2006-01-01

    Theoretical and empirical evidence are combined to show that underwater acoustic sensing techniques may be valuable for measuring the wind speed and determining the destructive power of a hurricane. This is done by first developing a model for the acoustic intensity and mutual intensity in an ocean waveguide due to a hurricane and then determining the relationship between local wind speed and underwater acoustic intensity. From this it is shown that it should be feasible to accurately measure the local wind speed and classify the destructive power of a hurricane if its eye wall passes directly over a single underwater acoustic sensor. The potential advantages and disadvantages of the proposed acoustic method are weighed against those of currently employed techniques. PMID:16454274

  17. Acoustic integrated extinction

    PubMed Central

    Norris, Andrew N.

    2015-01-01

    The integrated extinction (IE) is defined as the integral of the scattering cross section as a function of wavelength. Sohl et al. (2007 J. Acoust. Soc. Am. 122, 3206–3210. (doi:10.1121/1.2801546)) derived an IE expression for acoustic scattering that is causal, i.e. the scattered wavefront in the forward direction arrives later than the incident plane wave in the background medium. The IE formula was based on electromagnetic results, for which scattering is causal by default. Here, we derive a formula for the acoustic IE that is valid for causal and non-causal scattering. The general result is expressed as an integral of the time-dependent forward scattering function. The IE reduces to a finite integral for scatterers with zero long-wavelength monopole and dipole amplitudes. Implications for acoustic cloaking are discussed and a new metric is proposed for broadband acoustic transparency. PMID:27547100

  18. 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.

  19. 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.

  20. A pseudo-inverse algorithm for simultaneous measurements using multiple acoustical sources.

    PubMed

    Xiang, Ning; Li, Shu

    2007-03-01

    Simultaneous multiple acoustical sources measurement (SMASM) has been proposed for more effective and reliable identification of acoustical systems under critical conditions [N. Xiang and M. R. Schroeder, J. Acoust. Soc. Am. 113, 2754-2761 (2003); N. Xiang, J. N. Daigle, and M. Kleiner, J. Acoust. Soc. Am. 117, 1889-1894 (2005)]. This paper presents a pseudo-inverse algorithm for the SMASM correlation technique as an alternative way of extracting impulse responses of acoustical channels. Simulations and room acoustics experiments are carried out and the results prove the feasibility of the proposed algorithm. PMID:17407864

  1. Humanitarian mine detection by acoustic resonance

    SciTech Connect

    Kercel, S.W.

    1998-03-01

    The JASON Committee at MITRE Corp. was tasked by DARPA to inquire into suitable technologies for humanitarian mine detection. Acoustic resonance was one of the very few technologies that the JASONs determined might be promising for the task, but was as yet unexplored at the time that they conducted their inquiry. The objective of this Seed Money investigation into acoustic resonance was to determine if it would be feasible to use acoustic resonance to provide an improvement to present methods for humanitarian mine detection. As detailed in this report, acoustic resonance methods do not appear to be feasible for this task. Although acoustic resonant responses are relatively easy to detect when they exist, they are very difficult to excite by the non-contact means that must be used for buried objects. Despite many different attempts, this research did not discover any practical means of using sound to excite resonant responses in objects known to have strong resonances. The shaker table experiments did see an effect that might be attributable to the resonance of the object under test, but the effect was weak, and exploited the a priori knowledge of the resonant frequency of the object under test to distinguish it from the background. If experiments that used objects known to have strong acoustic resonances produced such marginal results, this does not seem to be a practical method to detect objects with weak resonances or non-existent resonances. The results of this work contribute to the ORNL countermine initiative. ORNL is exploring several unconventional mine detection technologies, and is proposed to explore others. Since this research has discovered some major pitfalls in non-metallic mine detection, this experience will add realism to other strategies proposed for mine detection technologies. The experiment provided hands-on experience with inert plastic mines under field conditions, and gives ORNL additional insight into the problems of developing practical

  2. Pregnant women's experiences of male partner involvement in the context of prevention of mother-to-child transmission in Khayelitsha, South Africa.

    PubMed

    Brittain, Kirsty; Giddy, Janet; Myer, Landon; Cooper, Diane; Harries, Jane; Stinson, Kathryn

    2015-01-01

    Male partner involvement (MPI) has been identified as a priority intervention in programmes for the prevention of mother-to-child transmission (PMTCT) of HIV, but rates of MPI remain low worldwide. This study used a quantitative survey (n=170) and two focus group discussions (FGDs) with 16 HIV-positive pregnant women attending a public sector antenatal care service in Khayelitsha, South Africa, to examine the determinants of high levels of involvement and generate a broader understanding of women's experiences of MPI during pregnancy. Among survey participants, 74% had disclosed their status to their partner, and most reported high levels of communication around HIV testing and preventing partner transmission, as well as high levels of MPI. High MPI was significantly more likely among women who were cohabiting with their partner; who had reportedly disclosed their HIV status to their partner; and who reported higher levels of HIV-related communication with their partner. FGD participants discussed a range of ways in which partners can be supportive during pregnancy, not limited to male attendance of antenatal care. MPI appears to be a feasible intervention in this context, and MPI interventions should aim to encourage male partner attendance of antenatal care as well as greater involvement in pregnancy more generally. Interventions that target communication are needed to facilitate HIV-related communication and disclosure within couples. MPI should remain a priority intervention in PMTCT programmes, and increased efforts should be made to promote MPI in PMTCT. PMID:25738960

  3. Towards acoustic UHE neutrino detection in the Mediterranean sea

    NASA Astrophysics Data System (ADS)

    Riccobene, G.

    2012-11-01

    Acoustic detection is proposed as a promising detection technique for Extreme High energy neutrinos. This technique is based on the detection of the acoustic signature of neutrino-induced showers in water: a bipolar signal, having a bandwidth of few 10 kHz, with cylindrical wave front. During the last decade, the possibility of access to deep-sea infrastructures developed for Cherenkov telescopes, allowed start-up of intense R&D activities on acoustic detection. In the framework of the activities of ANTARES, NEMO and KM3NeT, several small size experiments were run in order to measure acoustic noise in deep sea and test “neutrino-like” acoustic event detection. These activities have set milestones both for future HE neutrino detectors, for innovative deep-sea technology and for Earth-Sea science. A review on acoustic neutrino detection and projects running in the Mediterranean Sea is presented.

  4. Modal analysis and intensity of acoustic radiation of the kettledrum.

    PubMed

    Tronchin, Lamberto

    2005-02-01

    The acoustical features of kettledrums have been analyzed by means of modal analysis and acoustic radiation (p/v ratio) measurements. Modal analysis of two different kettledrums was undertaken, exciting the system both by a hammer and a shaker. Up to 15 vibrational modes were clearly identified. Acoustic radiation was studied using two ways. Based on previous experiments of other researchers, a new parameter, called intensity of acoustic radiation (IAR), has been defined and measured. Results show a strict relationship between IAR and the frequency response function (FRF, which is the v/F ratio), and IAR also strongly relates the modal pattern to acoustic radiation. Finally, IAR is proposed for vibro-acoustical characterization of kettledrums and other musical instruments such as strings, pianos, and harpsichords. PMID:15759711

  5. Observation of Marine Animals Using Underwater Acoustic Camera

    NASA Astrophysics Data System (ADS)

    Iida, Kohji; Takahashi, Rika; Tang, Yong; Mukai, Tohru; Sato, Masanori

    2006-05-01

    An underwater acoustic camera enclosed in a pressure-resistant case was constructed to observe underwater marine animals. This enabled the measurement of the size, shape, and behavior of living marine animals in the detection range up to 240 cm. The transducer array of the acoustic camera was driven by 3.5 MHz ultrasonic signals, and B-mode acoustic images were obtained. Observations were conducted for captive animals in a water tank and for natural animals in a field. The captive animals, including fish, squid and jellyfish, were observed, and a three-dimensional internal structure of animals was reconstructed using multiple acoustical images. The most important contributors of acoustic scattering were the swimbladder and vertebra of bladdered fish, and the liver and reproductive organs of invertebrate animals. In a field experiment, the shape, size, and swimming behavior of wild animals were observed. The possibilities and limitations of the underwater acoustic camera for fishery applications were discussed.

  6. Bioeffects due to acoustic droplet vaporization

    NASA Astrophysics Data System (ADS)

    Bull, Joseph

    2015-11-01

    Encapsulated micro- and nano-droplets can be vaporized via ultrasound, a process termed acoustic droplet vaporization. Our interest is primarily motivated by a developmental gas embolotherapy technique for cancer treatment. In this methodology, infarction of tumors is induced by selectively formed vascular gas bubbles that arise from the acoustic vaporization of vascular microdroplets. Additionally, the microdroplets may be used as vehicles for localized drug delivery, with or without flow occlusion. In this talk, we examine the dynamics of acoustic droplet vaporization through experiments and theoretical/computational fluid mechanics models, and investigate the bioeffects of acoustic droplet vaporization on endothelial cells and in vivo. Early timescale vaporization events, including phase change, are directly visualized using ultra-high speed imaging, and the influence of acoustic parameters on droplet/bubble dynamics is discussed. Acoustic and fluid mechanics parameters affecting the severity of endothelial cell bioeffects are explored. These findings suggest parameter spaces for which bioeffects may be reduced or enhanced, depending on the objective of the therapy. This work was supported by NIH grant R01EB006476.

  7. Producing undistorted acoustic sine waves.

    PubMed

    Boutin, Henri; Smith, John; Wolfe, Joe

    2014-04-01

    A simple digital method is described that can produce an undistorted acoustic sine wave using an amplifier and loudspeaker having considerable intrinsic distortion, a common situation at low frequencies and high power. The method involves, first, using a pure sine wave as the input and measuring the distortion products. An iterative procedure then progressively adds harmonics with appropriate amplitude and phase to cancel any distortion products. The method is illustrated by producing a pure 52 Hz sine wave at 107 dB sound pressure level with harmonic distortion reduced over the audible range to >65 dB below the fundamental. PMID:25234964

  8. Acoustic metamaterial design and applications

    NASA Astrophysics Data System (ADS)

    Zhang, Shu

    The explosion of interest in metamaterials is due to the dramatically increased manipulation ability over light as well as sound waves. This material research was stimulated by the opportunity to develop an artificial media with negative refractive index and the application in superlens which allows super-resolution imaging. High-resolution acoustic imaging techniques are the essential tools for nondestructive testing and medical screening. However, the spatial resolution of the conventional acoustic imaging methods is restricted by the incident wavelength of ultrasound. This is due to the quickly fading evanescent fields which carry the subwavelength features of objects. By focusing the propagating wave and recovering the evanescent field, a flat lens with negative-index can potentially overcome the diffraction limit. We present the first experimental demonstration of focusing ultrasound waves through a flat acoustic metamaterial lens composed of a planar network of subwavelength Helmholtz resonators. We observed a tight focus of half-wavelength in width at 60.5 KHz by imaging a point source. This result is in excellent agreement with the numerical simulation by transmission line model in which we derived the effective mass density and compressibility. This metamaterial lens also displays variable focal length at different frequencies. Our experiment shows the promise of designing compact and light-weight ultrasound imaging elements. Moreover, the concept of metamaterial extends far beyond negative refraction, rather giving enormous choice of material parameters for different applications. One of the most interesting examples these years is the invisible cloak. Such a device is proposed to render the hidden object undetectable under the flow of light or sound, by guiding and controlling the wave path through an engineered space surrounding the object. However, the cloak designed by transformation optics usually calls for a highly anisotropic metamaterial, which

  9. Evidence for liquid phase reactions during single bubble acoustic cavitation.

    PubMed

    Troia, A; Madonna Ripa, D; Lago, S; Spagnolo, R

    2004-07-01

    We extended the recent experiment by Lepoint et al. [Sonochemistry and Sonoluminescence, NATO ASI Series, Series C 524, Kluwer Academic Publishers, Dordrecht/Boston/London, 1999, p. 285], involving a so-called single bubble sonochemistry process, to a three-phase system. We have found experimental evidence that a single cavitating bubble can activate the oxidation of I- ions after the injection of a CCl4 liquid drop in the bubble trapping apparatus. The solvent drop (CCl4 is almost water insoluble) is pushed towards the bubble position and forms a thin film on the bubble surface. When the acoustic pressure drive is increased above 100 kPa, the three-phase system gives rise to a dark filament, indicating the complexation reaction between starch (added to the water phase) and I2. I2 species is the product of surface reactions involving bubble-induced decomposition of CCl4. Further increase of the acoustic drive causes the thin CCl4 film to separate from the bubble and stops I2 production. The study of the chemical activity of this three-phase system could give new advances on dynamics of the bubble collapse. PMID:15157862

  10. Acoustic Noise Prediction of the Amine Swingbed ISS ExPRESS Rack Payload

    NASA Technical Reports Server (NTRS)

    Welsh, David; Smith, Holly; Wang, Shuo

    2010-01-01

    Acoustics plays a vital role in maintaining the health, safety, and comfort of crew members aboard the International Space Station (ISS). In order to maintain this livable and workable environment, acoustic requirements have been established to ensure that ISS hardware and payload developers account for the acoustic emissions of their equipment and develop acoustic mitigations as necessary. These requirements are verified by an acoustic emissions test of the integrated hardware. The Amine Swingbed ExPRESS (Expedite the PRocessing of ExperimentS to Space) rack payload creates a unique challenge to the developers in that the payload hardware is transported to the ISS in phases, making an acoustic emissions test on the integrated flight hardware impossible. In addition, the payload incorporates a high back pressure fan and a diaphragm vacuum pump, which are recognized as significant and complex noise sources. In order to accurately predict the acoustic emissions of the integrated payload, the individual acoustic noise sources and paths are first characterized. These characterizations are conducted though a series of acoustic emissions tests on the individual payload components. Secondly, the individual acoustic noise sources and paths are incorporated into a virtual model of the integrated hardware. The virtual model is constructed with the use of hybrid method utilizing the Finite Element Acoustic (FEA) and Statistical Energy Analysis (SEA) techniques, which predict the overall acoustic emissions. Finally, the acoustic model is validated though an acoustic characterization test performed on an acoustically similar mock-up of the flight unit. The results of the validated acoustic model are then used to assess the acoustic emissions of the flight unit and define further acoustic mitigation efforts.

  11. Observations of dust acoustic waves driven at high frequencies: Finite dust temperature effects and wave interference

    SciTech Connect

    Thomas, Edward Jr.; Fisher, Ross; Merlino, Robert L.

    2007-12-15

    An experiment has been performed to study the behavior of dust acoustic waves driven at high frequencies (f>100 Hz), extending the range of previous work. In this study, two previously unreported phenomena are observed--interference effects between naturally excited dust acoustic waves and driven dust acoustic waves, and the observation of finite dust temperature effects on the dispersion relation.

  12. Seismicity triggered by the olivine-spinel transition: new insights from combined XRD and acoustic emission monitoring during deformation experiments in Mg2GeO4

    NASA Astrophysics Data System (ADS)

    Schubnel, A.; Hilairet, N.; Brunet, F.; Gasc, J.; Cordier, P.; Wang, Y.; Green, H. W.

    2012-04-01

    Polycrystalline Mg2GeO4-olivine has been deformed (strain rates from 2.10-4/s to 10-5/s) in the deformation-DIA in 13-BM-D at GSECARS (Advanced Photon Source) at ca. 2 GPa confining pressure for temperatures between 973 and 1573 K (i.e., in the Mg2GeO4-ringwoodite field). Stress, advancement of transformation, and strain were measured in-situ using X-ray diffraction (XRD) and imaging, and acoustic emissions (AE) were recorded simultaneously. When differential stress is applied (ca. 1- to 2 GPa) and temperature is increased, the very beginning of the transformation to the ringwoodite structure (as evidenced by in situ XRD) is accompanied by AE bursts which locate within the sample. At high strain rates (>10-4/s) and low temperatures (800-900 degrees C), the number of AEs is comparable, if not larger, to that observed during the cold compression of quartz grains. The largest events always occur at a temperature slightly below that of appearance of the ringwoodite-structure phase on the XRD images patterns. This suggests that AEs are generated while the transition is still nucleation controlled (pseudo-martensitic stage). During stress-relaxation periods, the rate of AE triggering decreases, but does not completely vanish. Importantly, we still observed very large AEs at strain rates as low as approx. 10-5/ s, while at these early stages of the transformation, the samples did not show any macroscopic rheological weakening. Focal mechanism analysis of the largest AEs showed that they are all of shear type, some being even pure double couple. They radiate about the same amount of energy as typically recorded during fast crack propagation in amorphous glass material. Microstructural analysis (SEM, EBSD and TEM) highlights the presence of thin transformation bands, with plausible evidence of shear (grain distortion and grain size reduction). These bands are made of incoherent spinel and olivine nano-grains which run across germanium-olivine grain boundaries. These bands

  13. Seismicity triggered by the olivine-spinel transition: new insights from combined XRD and acoustic emission monitoring during deformation experiments in Mg2GeO4

    NASA Astrophysics Data System (ADS)

    Schubnel, A. J.; Hilairet, N.; Brunet, F.; Héripré, E.; Cordier, P.; Wang, Y.

    2011-12-01

    Polycrystalline Mg2GeO4-olivine has been deformed (strain rates from 2.10-4/s to 10-5/s) in the deformation-DIA in 13-BM-D at GSECARS (Advanced Photon Source) at ca. 2 GPa confining pressure for temperatures between 973 and 1573 K (i.e., in the Mg2GeO4-ringwoodite field). Stress, advancement of transformation, and strain were measured in-situ using X-ray diffraction (XRD) and imaging, and acoustic emissions (AE) were recorded simultaneously. When differential stress is applied (ca. 1- to 2 GPa) and temperature is increased, the very beginning of the transformation to the ringwoodite structure (as evidenced by in situ XRD) is accompanied by AE bursts which locate within the sample. At high strain rates (>10-4/s) and low temperatures (800-900 degrees C), the number of AEs is comparable, if not larger, to that observed during the cold compression of quartz grains. The largest events always occur at a temperature slightly below that of appearance of the ringwoodite-structure phase on the XRD images patterns. This suggests that AEs are generated while the transition is still nucleation controlled (pseudo-martensitic stage). During stress-relaxation periods, the rate of AE triggering decreases, but does not completely vanish. Importantly, we still observed very large AEs at strain rates as low as approx. 10-5/ s, while at these early stages of the transformation, the samples did not show any macroscopic rheological weakening. Focal mechanism analysis of the largest AEs showed that they are all of shear type, some being even pure double couple. They radiate about the same amount of energy as typically recorded during fast crack propagation in amorphous glass material. Microstructural analysis (SEM, EBSD and TEM) highlights the presence of thin transformation bands, with plausible evidence of shear (grain distortion and grain size reduction). These bands are made of incoherent spinel and olivine nano-grains which run across germanium-olivine grain boundaries. These bands

  14. The social effects of poor classroom acoustics on students and The District of Columbia Public Schools demonstration of support through mandating the ANSI Classroom Acoustics standard

    NASA Astrophysics Data System (ADS)

    Ellis, Donna

    2002-11-01

    The effects that poor acoustics have on students extend beyond the classroom. This paper is to discuss the immediate and long-term results that inadequate acoustical design in the educational setting has on academic and social development and how the District of Columbia Public Schools (DCPS) are contributing to the classroom acoustic movement. DCPS is taking a pro-active stance in educational acoustics by mandating the ANSI Draft S12.60-200X classroom acoustic standard in the transformation of ten schools a year for the next ten to fifteen years. Synthesizing the ANSI S12 standard with the DCPS Design Guidelines describes explanation of how to design for appropriate acoustics in all core-learning spaces. Examples of the existing conditions of the facilities and acoustical remediation for new and historical preservation projects will be demonstrated. In addition, experience will be shared on the International Building Code Council hearings for classroom acoustics.

  15. Mortality and cancer registration experience of the Sellafield workers known to have been involved in the 1957 Windscale accident: 50 year follow-up.

    PubMed

    McGeoghegan, D; Whaley, S; Binks, K; Gillies, M; Thompson, K; McElvenny, D M

    2010-09-01

    of involvement in the Windscale fire was - 5.53% (se = 3.81, p = 0.15) for all cancers mortality and 6.60% (se = 4.03%, p = 0.10) for IHD mortality though neither figure was statistically significant. This analysis of the mortality and cancer morbidity experience of those Sellafield workers involved in the 1957 Windscale fire does not reveal any measurable effect of the fire upon their health. Although this study has low statistical power for detecting small adverse effects, due to the relatively small number of workers, it does provide reassurance that no significant health effects are associated with the 1957 Windscale fire even after 50 years of follow-up. PMID:20798473

  16. Software for Acoustic Rendering

    NASA Technical Reports Server (NTRS)

    Miller, Joel D.

    2003-01-01

    SLAB is a software system that can be run on a personal computer to simulate an acoustic environment in real time. SLAB was developed to enable computational experimentation in which one can exert low-level control over a variety of signal-processing parameters, related to spatialization, for conducting psychoacoustic studies. Among the parameters that can be manipulated are the number and position of reflections, the fidelity (that is, the number of taps in finite-impulse-response filters), the system latency, and the update rate of the filters. Another goal in the development of SLAB was to provide an inexpensive means of dynamic synthesis of virtual audio over headphones, without need for special-purpose signal-processing hardware. SLAB has a modular, object-oriented design that affords the flexibility and extensibility needed to accommodate a variety of computational experiments and signal-flow structures. SLAB s spatial renderer has a fixed signal-flow architecture corresponding to a set of parallel signal paths from each source to a listener. This fixed architecture can be regarded as a compromise that optimizes efficiency at the expense of complete flexibility. Such a compromise is necessary, given the design goal of enabling computational psychoacoustic experimentation on inexpensive personal computers.

  17. Acoustic cooling engine

    DOEpatents

    Hofler, Thomas J.; Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1988-01-01

    An acoustic cooling engine with improved thermal performance and reduced internal losses comprises a compressible fluid contained in a resonant pressure vessel. The fluid has a substantial thermal expansion coefficient and is capable of supporting an acoustic standing wave. A thermodynamic element has first and second ends and is located in the resonant pressure vessel in thermal communication with the fluid. The thermal response of the thermodynamic element to the acoustic standing wave pumps heat from the second end to the first end. The thermodynamic element permits substantial flow of the fluid through the thermodynamic element. An acoustic driver cyclically drives the fluid with an acoustic standing wave. The driver is at a location of maximum acoustic impedance in the resonant pressure vessel and proximate the first end of the thermodynamic element. A hot heat exchanger is adjacent to and in thermal communication with the first end of the thermodynamic element. The hot heat exchanger conducts heat from the first end to portions of the resonant pressure vessel proximate the hot heat exchanger. The hot heat exchanger permits substantial flow of the fluid through the hot heat exchanger. The resonant pressure vessel can include a housing less than one quarter wavelength in length coupled to a reservoir. The housing can include a reduced diameter portion communicating with the reservoir. The frequency of the acoustic driver can be continuously controlled so as to maintain resonance.

  18. Nonlinear acoustic wave propagation in atmosphere

    NASA Technical Reports Server (NTRS)

    Hariharan, S. I.

    1985-01-01

    A model problem that simulates an atmospheric acoustic wave propagation situation that is nonlinear is considered. The model is derived from the basic Euler equations for the atmospheric flow and from the regular perturbations for the acoustic part. The nonlinear effects are studied by obtaining two successive linear problems in which the second one involves the solution of the first problem. Well posedness of these problems is discussed and approximations of the radiation boundary conditions that can be used in numerical simulations are presented.

  19. 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.

  20. Acoustofluidics 5: Building microfluidic acoustic resonators.

    PubMed

    Lenshof, A; Evander, M; Laurell, T; Nilsson, J

    2012-02-21

    Acoustophoresis is getting more attention as an effective and gentle non-contact method of manipulating cells and particles in microfluidic systems. A key to a successful assembly of an acoustophoresis system is a proper design of the acoustic resonator where aspects of fabrication techniques, material choice, thickness matching of involved components, as well as strategies of actuation, all have to be considered. This tutorial covers some of the basics in designing and building microfluidic acoustic resonators and will hopefully be a comprehensive and advisory document to assist the interested reader in creating a successful acoustophoretic device. PMID:22246532

  1. Nonlinear acoustic wave propagation in atmosphere

    NASA Technical Reports Server (NTRS)

    Hariharan, S. I.

    1986-01-01

    In this paper a model problem is considered that simulates an atmospheric acoustic wave propagation situation that is nonlinear. The model is derived from the basic Euler equations for the atmospheric flow and from the regular perturbations for the acoustic part. The nonlinear effects are studied by obtaining two successive linear problems in which the second one involves the solution of the first problem. Well-posedness of these problems is discussed and approximations of the radiation boundary conditions that can be used in numerical simulations are presented.

  2. Acoustic modeling of the speech organ

    NASA Astrophysics Data System (ADS)

    Kacprowski, J.

    The state of research on acoustic modeling of phonational and articulatory speech producing elements is reviewed. Consistent with the physical interpretation of the speech production process, the acoustic theory of speech production is expressed as the product of three factors: laryngeal involvement, sound transmission, and emanations from the mouth and/or nose. Each of these factors is presented in the form of a simplified mathematical description which provides the theoretical basis for the formation of physical models of the appropriate functional members of this complex bicybernetic system. Vocal tract wall impedance, vocal tract synthesizers, laryngeal dysfunction, vowel nasalization, resonance circuits, and sound wave propagation are discussed.

  3. Some Problems of modern acoustics

    NASA Technical Reports Server (NTRS)

    Stan, A.

    1974-01-01

    The multidisciplinary and interdisciplinary character of acoustics is considered and its scientific, technological, economical and social implications, as well as the role of acoustics in creating new machines and equipment and improving the quality of products are outlined. Research beyond audible frequencies, as well as to extremely high acoustic intensities, which requires the development of a nonlinear acoustics is elaborated.

  4. How parents and practitioners experience research without prior consent (deferred consent) for emergency research involving children with life threatening conditions: a mixed method study

    PubMed Central

    Woolfall, Kerry; Frith, Lucy; Gamble, Carrol; Gilbert, Ruth; Mok, Quen; Young, Bridget

    2015-01-01

    Objective Alternatives to prospective informed consent to enable children with life-threatening conditions to be entered into trials of emergency treatments are needed. Across Europe, a process called deferred consent has been developed as an alternative. Little is known about the views and experiences of those with first-hand experience of this controversial consent process. To inform how consent is sought for future paediatric critical care trials, we explored the views and experiences of parents and practitioners involved in the CATheter infections in CHildren (CATCH) trial, which allowed for deferred consent in certain circumstances. Design Mixed method survey, interview and focus group study. Participants 275 parents completed a questionnaire; 20 families participated in an interview (18 mothers, 5 fathers). 17 CATCH practitioners participated in one of four focus groups (10 nurses, 3 doctors and 4 clinical trial unit staff). Setting 12 UK children's hospitals. Results Some parents were momentarily shocked or angered to discover that their child had or could have been entered into CATCH without their prior consent. Although these feelings resolved after the reasons why consent needed to be deferred were explained and that the CATCH interventions were already used in clinical care. Prior to seeking deferred consent for the first few times, CATCH practitioners were apprehensive, although their feelings abated with experience of talking to parents about CATCH. Parents reported that their decisions about their child's participation in the trial had been voluntary. However, mistiming the deferred consent discussion had caused distress for some. Practitioners and parents supported the use of deferred consent in CATCH and in future trials of interventions already used in clinical care. Conclusions Our study provides evidence to support the use of deferred consent in paediatric emergency medicine; it also indicates the crucial importance of practitioner communication

  5. Considerations on the acoustic energy radiated by toothed gears. [model for calculating noise intensity

    NASA Technical Reports Server (NTRS)

    Popinceanu, N. G.; Kremmer, I.

    1974-01-01

    A mechano-acoustic model is reported for calculating acoustic energy radiated by a working gear. According to this model, a gear is an acoustic coublet formed of the two wheels. The wheel teeth generate cylindrical acoustic waves while the front surfaces of the teeth behave like vibrating pistons. Theoretical results are checked experimentally and good agreement is obtained with open gears. The experiments show that the air noise effect is negligible as compared with the structural noise transmitted to the gear box.

  6. Acoustic well cleaner

    DOEpatents

    Maki, Jr., Voldi E.; Sharma, Mukul M.

    1997-01-21

    A method and apparatus are disclosed for cleaning the wellbore and the near wellbore region. A sonde is provided which is adapted to be lowered into a borehole and which includes a plurality of acoustic transducers arranged around the sonde. Electrical power provided by a cable is converted to acoustic energy. The high intensity acoustic energy directed to the borehole wall and into the near wellbore region, redissolves or resuspends the material which is reducing the permeability of the formation and/or restricting flow in the wellbore.

  7. 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.

  8. PRSEUS Acoustic Panel Fabrication

    NASA Technical Reports Server (NTRS)

    Nicolette, Velicki; Yovanof, Nicolette P.; Baraja, Jaime; Mathur, Gopal; Thrash, Patrick; Pickell, Robert

    2011-01-01

    This report describes the development of a novel structural concept, Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS), that addresses the demanding fuselage loading requirements for the Hybrid Wing or Blended Wing Body (BWB) airplane configuration with regards to acoustic response. A PRSEUS panel was designed and fabricated and provided to NASA-LaRC for acoustic response testing in the Structural Acoustics Loads and Transmission (SALT) facility). Preliminary assessments of the sound transmission characteristics of a PRSEUS panel subjected to a representative Hybrid Wing Body (HWB) operating environment were completed for the NASA Environmentally Responsible Aviation (ERA) Program.

  9. Acoustical heat pumping engine

    DOEpatents

    Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1983-08-16

    The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium.

  10. Acoustical heat pumping engine

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1983-08-16

    The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium. 2 figs.

  11. Perceptual integration of acoustic cues to laryngeal contrasts in Korean fricatives.

    PubMed

    Lee, Sarah; Katz, Jonah

    2016-02-01

    This paper provides evidence that multiple acoustic cues involving the presence of low-frequency energy integrate in the perception of Korean coronal fricatives. This finding helps explain a surprising asymmetry between the production and perception of these fricatives found in previous studies: lower F0 onset in the following vowel leads to a response bias for plain [s] over fortis [s*], despite the fact that there is no evidence for a corresponding acoustic asymmetry in the production of [s] and [s*]. A fixed classification task using the Garner paradigm provides evidence that low F0 in a following vowel and the presence of voicing during frication perceptually integrate. This suggests that Korean listeners in previous experiments were responding to an "intermediate perceptual property" of stimuli, despite the fact that the individual acoustic components of that property are not all present in typical Korean fricative productions. The finding also broadens empirical support for the general idea of perceptual integration to a language, a different manner of consonant, and a situation where covariance of the acoustic cues under investigation is not generally present in a listener's linguistic input. PMID:26936544

  12. The acoustic monopole in motion

    NASA Technical Reports Server (NTRS)

    Norum, T. D.; Liu, C. H.

    1976-01-01

    The results of an experiment are presented in which a small monochromatic source which behaves like an acoustic monopole when stationary is moved at a constant speed over an asphalt surface past stationary microphones. An analysis of the monopole moving above a finite impedance reflecting plane is given. The theoretical and experimental results are compared for different ground to observer heights, source frequencies, and source velocities. A computation of the effects of source acceleration on the noise radiated by the monopole is also presented.

  13. Can biophysics tell us something about the weak equivalence principle vis a vis the thought experiment of Einstein involving human subjects?

    PubMed

    Thaheld, Fred H

    2009-08-01

    Over a period of several decades it has been noticed that most astronauts, either orbiting the earth or on trips to the moon, have observed phosphenes or light flashes (LF) including streaks, spots and clouds of light when their eyes are closed or they are in a darkened cabin. Scientists suspect that two separate components of cosmic rays cause these flashes due to direct interaction with the retina. This phenomenon is not noticed on the ground because of cosmic ray interaction with the atmosphere. The argument is advanced that this effect may provide us with a new method of exploring the weak equivalence principle from the standpoint of Einstein's original thought experiment involving human subjects. This can be done, utilizing the retina only, as an animate quantum mechanical measuring device or, in conjunction with the Anomalous Long Term Effects on Astronauts (ALTEA) facility. PMID:19426781

  14. Nonlinear acoustic fields in acoustic metamaterial based on a cylindrical pipe with periodically arranged side holes.

    PubMed

    Fan, Li; Ge, Huan; Zhang, Shu-yi; Gao, Hai-fei; Liu, Yong-hui; Zhang, Hui

    2013-06-01

    Nonlinear acoustic fields in transmission-line acoustic metamaterials based on a cylindrical pipe with periodically arranged side holes are studied, in which the dispersions and characteristic parameters of the nonlinear acoustic waves are obtained with the Bloch theory, and meanwhile the distributions of the fundamental wave (FW) and second harmonic wave (SHW) in the metamaterial are simulated. Three characteristic frequency bands are defined according to the relations between the frequencies of the FW, SHW, and the low-frequency forbidden band (LFB) in the metamaterial. Especially, when the FW is in the LFB while the SHW is outside the LFB, the SHW can transmit through the metamaterial although the FW is blocked, which exhibits the possibility to extract the information from the SHW instead of the FW. In addition, experiments are carried out to measure the distributions of the acoustic pressures for the FW and SHW along the metamaterial and the experimental results are in agreement with the theory. PMID:23742339

  15. The 5-Year EFS of Multisystem LCH With Risk-Organ Involvement Is Suboptimal: A Single-center Experience From India.

    PubMed

    Totadri, Sidharth; Bansal, Deepak; Trehan, Amita; Srinivasan, Radhika; Varma, Neelam; Kakkar, Nandita; Saxena, Akshay K; Bhatia, Prateek

    2016-01-01

    The study describes an 8-year experience of a single center in managing patients with langerhans cell histiocytosis on the basis of the langerhans cell histiocytosis-III platform. A retrospective case-file review of children diagnosed during 2006 to 2013 was performed. Group 1 (multisystem with risk-organ involvement) patients received an initial treatment of 6 to 12 weeks, followed by continuation treatment to complete 12 months. Drugs included vinblastine, prednisolone, and 6-mercaptopurine. Group 2 (multisystem without risk-organ involvement) patients received a similar treatment, except for 6-mercaptopurine. Group 3 (single-system/multifocal bone disease) patients were treated for a duration of 6 months. Forty-nine patients were treated: 24 (49%), 14 (28.6%), and 11 (22.4%) in groups 1, 2, and 3, respectively. The mean age at diagnosis was 31.6 ± 28.4 months (range, 4 to 120 mo). Five patients abandoned treatment. There were 7 deaths, all in group 1. All patients who died had either a partial response or progressive disease after induction (P=0.000). Among patients with liver involvement, those with sclerosing cholangitis had a greater mortality (P=0.007). A relapse was observed in 12 (24.5%) patients. The frequency of relapse was not different in the 3 groups (P=0.833). The 5-year event-free survival in groups 1, 2, and 3 was 29.3 ± 10%, 58.9 ± 14.6%, and 69.3 ± 15%, respectively (P=0.019). The 5-year overall survival was 100% in groups 2/3 and 68.9 ± 9.8% in group 1 (P=0.011). PMID:26274033

  16. Imaging of Acoustic Waves in Sand

    SciTech Connect

    Deason, Vance Albert; Telschow, Kenneth Louis; Watson, Scott Marshall

    2003-08-01

    There is considerable interest in detecting objects such as landmines shallowly buried in loose earth or sand. Various techniques involving microwave, acoustic, thermal and magnetic sensors have been used to detect such objects. Acoustic and microwave sensors have shown promise, especially if used together. In most cases, the sensor package is scanned over an area to eventually build up an image or map of anomalies. We are proposing an alternate, acoustic method that directly provides an image of acoustic waves in sand or soil, and their interaction with buried objects. The INEEL Laser Ultrasonic Camera utilizes dynamic holography within photorefractive recording materials. This permits one to image and demodulate acoustic waves on surfaces in real time, without scanning. A video image is produced where intensity is directly and linearly proportional to surface motion. Both specular and diffusely reflecting surfaces can be accomodated and surface motion as small as 0.1 nm can be quantitatively detected. This system was used to directly image acoustic surface waves in sand as well as in solid objects. Waves as frequencies of 16 kHz were generated using modified acoustic speakers. These waves were directed through sand toward partially buried objects. The sand container was not on a vibration isolation table, but sat on the lab floor. Interaction of wavefronts with buried objects showed reflection, diffraction and interference effects that could provide clues to location and characteristics of buried objects. Although results are preliminary, success in this effort suggests that this method could be applied to detection of buried landmines or other near-surface items such as pipes and tanks.

  17. Acoustic Neuroma Association

    MedlinePlus

    ... Platinum Sponsors More from this sponsor... Platinum Sponsor Gold Sponsor University of Colorado Acoustic Neuroma Program Rocky Mountain Gamma Knife Center Gold Sponsor NYU Langone Medical Center Departments of Neurosurgery ...

  18. 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.

  19. 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.

  20. Acoustics lecturing in Mexico

    NASA Astrophysics Data System (ADS)

    Beristain, Sergio

    2002-11-01

    Some thirty years ago acoustics lecturing started in Mexico at the National Polytechnic Institute in Mexico City, as part of the Bachelor of Science degree in Communications and Electronics Engineering curricula, including the widest program on this field in the whole country. This program has been producing acoustics specialists ever since. Nowadays many universities and superior education institutions around the country are teaching students at the B.Sc. level and postgraduate level many topics related to acoustics, such as Architectural Acoustics, Seismology, Mechanical Vibrations, Noise Control, Audio, Audiology, Music, etc. Also many institutions have started research programs in related fields, with participation of medical doctors, psychologists, musicians, engineers, etc. Details will be given on particular topics and development.

  1. 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.

  2. 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.

  3. Effects of intra-prelimbic prefrontal cortex injection of cannabidiol on anxiety-like behavior: involvement of 5HT1A receptors and previous stressful experience.

    PubMed

    Fogaça, M V; Reis, F M C V; Campos, A C; Guimarães, F S

    2014-03-01

    The prelimbic medial prefrontal cortex (PL) is an important encephalic structure involved in the expression of emotional states. In a previous study, intra-PL injection of cannabidiol (CBD), a major non-psychotomimetic cannabinoid present in the Cannabis sativa plant, reduced the expression of fear conditioning response. Although its mechanism remains unclear, CBD can facilitate 5HT1A receptor-mediated neurotransmission when injected into several brain structures. This study was aimed at verifying if intra-PL CBD could also induce anxiolytic-like effect in a conceptually distinct animal model, the elevated plus maze (EPM). We also verified if CBD effects in the EPM and contextual fear conditioning test (CFC) depend on 5HT1A receptors and previous stressful experience. CBD induced opposite effects in the CFC and EPM, being anxiolytic and anxiogenic, respectively. Both responses were prevented by WAY100,635, a 5HT1A receptor antagonist. In animals that had been previously (24h) submitted to a stressful event (2h-restraint) CBD caused an anxiolytic, rather than anxiogenic, effect in the EPM. This anxiolytic response was abolished by previous injection of metyrapone, a glucocorticoid synthesis blocker. Moreover, restraint stress increased 5HT1A receptors expression in the dorsal raphe nucleus, an effect that was attenuated by injection of metyrapone before the restraint procedure. Taken together, these results suggest that CBD modulation of anxiety in the PL depend on 5HT1A-mediated neurotransmission and previous stressful experience. PMID:24321837

  4. EXPERIENCES OF HIV/AIDS STIGMA OF PERSONS LIVING WITH HIV/AIDS AND NURSES INVOLVED IN THEIR CARE FROM FIVE AFRICAN COUNTRIES

    PubMed Central

    Greeff, Minrie; Uys, Leana R; Holzemer, William L; Makoae, Lucia N; Dlamini, Priscilla S; Kohi, Thecla W; Chirwa, Maureen L; Naidoo, Joanne R; Phetlhu, Rene D.

    2009-01-01

    The concept of stigma has received significant attention in recent years in the HIV/AIDS literature. Although there is some change towards the positive, AIDS still remains a significantly stigmatized condition. AIDS stigma and discrimination continue to influence people living with and affected by HIV (PLWA), as well as their health-care providers. Unless stigma is conquered, the illness will not be defeated. Due to the burden that HIV/AIDS places on people living in Africa, a five-year project entitled Perceived AIDS Stigma: A Multinational African Study was undertaken. The focus of the first phase of this project was on exploring and describing the meaning and effect of stigma on PLWA from the experiences of PLWA and the nurses involved in their care in five African countries: Lesotho, Swaziland, Malawi, South Africa and Tanzania. An exploratory descriptive qualitative research design was used to explore and describe the experience of stigma through the critical incident method. Purposive voluntary sampling was utilized. Forty-three focus group discussions were held with respondents to relate incidences which they themselves observed, as well as those that they themselves experienced in the community and in families. The transcribed data was analyzed through the technique of open coding using the NVivo 2.0 analysis package. Three types of stigma (received stigma, internal stigma and associated stigma) and several dimensions for each of these types of stigma emerged from the data. Recommendations were made to pursue these findings further. PMID:20052299

  5. EXPERIENCES OF HIV/AIDS STIGMA OF PERSONS LIVING WITH HIV/AIDS AND NURSES INVOLVED IN THEIR CARE FROM FIVE AFRICAN COUNTRIES.

    PubMed

    Greeff, Minrie; Uys, Leana R; Holzemer, William L; Makoae, Lucia N; Dlamini, Priscilla S; Kohi, Thecla W; Chirwa, Maureen L; Naidoo, Joanne R; Phetlhu, Rene D

    2008-01-01

    The concept of stigma has received significant attention in recent years in the HIV/AIDS literature. Although there is some change towards the positive, AIDS still remains a significantly stigmatized condition. AIDS stigma and discrimination continue to influence people living with and affected by HIV (PLWA), as well as their health-care providers. Unless stigma is conquered, the illness will not be defeated. Due to the burden that HIV/AIDS places on people living in Africa, a five-year project entitled Perceived AIDS Stigma: A Multinational African Study was undertaken. The focus of the first phase of this project was on exploring and describing the meaning and effect of stigma on PLWA from the experiences of PLWA and the nurses involved in their care in five African countries: Lesotho, Swaziland, Malawi, South Africa and Tanzania. An exploratory descriptive qualitative research design was used to explore and describe the experience of stigma through the critical incident method. Purposive voluntary sampling was utilized. Forty-three focus group discussions were held with respondents to relate incidences which they themselves observed, as well as those that they themselves experienced in the community and in families. The transcribed data was analyzed through the technique of open coding using the NVivo 2.0 analysis package. Three types of stigma (received stigma, internal stigma and associated stigma) and several dimensions for each of these types of stigma emerged from the data. Recommendations were made to pursue these findings further. PMID:20052299

  6. Comparing Volcano Infrasound and Aeroacoustics Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Ogden, D. E.; Matoza, R. S.; Fee, D.

    2012-12-01

    The production of acoustic noise by fluid flows has been studied experimentally within engineering aeroacoustics for over 50 years. These works aim to correlate flow properties and dynamics with the produced acoustic spectra (i.e., patterns of frequencies and amplitude). These correlations are used to design flow fields in man-made jet engines and other machines to reduce the production of harmful acoustic signals and resulting hearing loss. Many of the flow fields in these man-made systems are analogous to those in volcanic eruptions. We postulate that the acoustic signals generated by these flows are also analogous and the aeroacoustics experimental results provide a starting point for modeling the noise generated by volcanic flow fields. Application of empirical results from these experiments to volcanic flow fields is non-trivial. Volcanic eruptions involve complexities not present in man-made experiments including but not limited to multiphase flow, buoyancy forces, and non-uniform atmosphere. This work explores methods by which some of the empirical results from aeroacoustics experiments can be modified for application to volcanic eruptions. Results are compared with observations of volcano infrasound. Preliminary comparison to numerical simulations of volcano infrasound may also be presented.

  7. Interfacial destabilization and atomization driven by surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Qi, Aisha; Yeo, Leslie Y.; Friend, James R.

    2008-07-01

    Surface acoustic wave atomization is a rapid means for generating micron and submicron aerosol droplets. Little, however, is understood about the mechanisms by which these droplets form due to the complex hydrodynamic processes that occur across widely varying length and time scales. Through experiments, scaling theory, and simple numerical modeling, we elucidate the interfacial destabilization mechanisms that lead to droplet formation. Using a millimeter-order fluid drop exposed to surface acoustic waves as it sits atop a single-crystal lithium niobate piezoelectric substrate, large aerosol droplets on the length scale of the parent drop dimension are ejected through a whipping and pinch-off phenomenon, which occurs at the asymmetrically formed crest of the drop due to leakage of acoustic radiation at the Rayleigh angle. Smaller micron order droplets, on the other hand, are formed due to the axisymmetric breakup of cylindrical liquid jets that are ejected as a consequence of interfacial destabilization. The 10μm droplet dimension correlates with the jet radius and the instability wavelength, both determined from a simple scaling argument involving a viscous-capillary dominant force balance. The results are further supported by numerical solution of the evolution equation governing the interfacial profile of a sessile drop along which an acoustic pressure wave is imposed. Viscous and capillary forces dominate in the bulk of the parent drop, but inertia is dominant in the ejected jets and within a thin boundary layer adjacent to the substrate where surface and interfacial accelerations are large. With the specific exception of parent drops that spread into thin films with thicknesses on the order of the boundary layer dimension prior to atomization, the free surface of the drop is always observed to vibrate at the capillary-viscous resonance frequency—even if the exciting frequency of the surface acoustic wave is several orders of magnitude larger—contrary to

  8. Acoustic characterization of developmental speech disorders

    NASA Astrophysics Data System (ADS)

    Bunnell, H. Timothy; Polikoff, James; McNicholas, Jane; Walter, Rhonda; Winn, Matthew

    2001-05-01

    A novel approach to classifying children with developmental speech delays (DSD) involving /r/ was developed. The approach first derives an acoustic classification of /r/ tokens based on their forced Viterbi alignment to a five-state hidden Markov model (HMM) of normally articulated /r/. Children with DSD are then classified in terms of the proportion of their /r/ productions that fall into each broad acoustic class. This approach was evaluated using 953 examples of /r/ as produced by 18 DSD children and an approximately equal number of /r/ tokens produced by a much larger number of normally articulating children. The acoustic classification identified three broad categories of /r/ that differed substantially in how they aligned to the normal speech /r/ HMM. Additionally, these categories tended to partition tokens uttered by DSD children from those uttered by normally articulating children. Similarities among the DSD children and average normal child measured in terms of the proportion of their /r/ productions that fell into each of the three broad acoustic categories were used to perform a hierarchical clustering. This clustering revealed groupings of DSD children who tended to approach /r/ production in one of several acoustically distinct manners.

  9. Numerical Techniques in Acoustics

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J. (Compiler)

    1985-01-01

    This is the compilation of abstracts of the Numerical Techniques in Acoustics Forum held at the ASME's Winter Annual Meeting. This forum was for informal presentation and information exchange of ongoing acoustic work in finite elements, finite difference, boundary elements and other numerical approaches. As part of this forum, it was intended to allow the participants time to raise questions on unresolved problems and to generate discussions on possible approaches and methods of solution.

  10. Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface.

    PubMed

    Xie, Yangbo; Wang, Wenqi; Chen, Huanyang; Konneker, Adam; Popa, Bogdan-Ioan; Cummer, Steven A

    2014-01-01

    Metasurfaces are a family of novel wavefront-shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality to their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as acoustic imaging, beam steering, ultrasound lens design and acoustic surface wave-based applications. PMID:25418084

  11. Squaring Up: Experiences of Transition from Off-Street Sex Work to Square Work and Duality--Concurrent Involvement in Both--in Vancouver, BC.

    PubMed

    Bowen, Raven R

    2015-11-01

    Many studies of exit from sex work are inspired by role theory, where people experience a lack of attachment to a role; are faced with individual, interactional, and structural challenges; contemplate transition and exit a role; and then struggle to establish postrole identities and new lives. This framework has been used to explicate the factors and experiences of those who leave or attempt to leave the sex industry; however, it is limited because studies present sex work as a harmful and dangerous profession that people are trapped in, escaping, or have survived. In this paper, I discuss Vancouver's history of violence against sex workers and I review research on sex work exiting and bring forward recommendations for the design of exit program based on the experiences of 22 active and former off-street sex workers from Vancouver, British Columbia. I describe study participants who include Sex-Work-No-More participants who would not return to the industry, Sex-Work-Maybe participants who consider reinvolvement, and Dual-Life participants who are employed in sex work and conventional work simultaneously. These participants uniquely challenge narrow, binary understandings of involvement and transition because they discuss their use of deception to obtain resources needed to make change; the support that clients have provided; their strategic engagement in sex work as a means to exit; their considerations of reentry; and for some, their dual employment. In light of new legislation that criminalizes activities related to sex work-the Protection of Communities and Exploited Persons Act-and the Federal government announcement of $20 million dollars for the creation of exit services nationwide, hearing from sex workers is essential to advancing agendas in this area. PMID:26577882

  12. Acoustic communication by ants

    NASA Astrophysics Data System (ADS)

    Hickling, Robert

    2002-05-01

    Many ant species communicate acoustically by stridulating, i.e., running a scraper over a washboard-like set of ridges. Ants appear to be insensitive to airborne sound. Consequently, myrmecologists have concluded that the stridulatory signals are transmitted through the substrate. This has tended to diminish the importance of acoustic communication, and it is currently believed that ant communication is based almost exclusively on pheromones, with acoustic communication assigned an almost nonexistent role. However, it can be shown that acoustic communication between ants is effective only if the medium is air and not the substrate. How, then, is it possible for ants to appear deaf to airborne sound and yet communicate through the air? An explanation is provided in a paper [R. Hickling and R. L. Brown, ``Analysis of acoustic communication by ants,'' J. Acoust. Soc. Am. 108, 1920-1929 (2000)]. Ants are small relative to the wavelengths they generate. Hence, they create a near field, which is characterized by a major increase in sound velocity (particle velocity of sound) in the vicinity of the source. Hair sensilla on the ants' antennae respond to sound velocity. Thus, ants are able to detect near-field sound from other ants and to exclude extraneous airborne sound.

  13. Acoustic detection of pneumothorax

    NASA Astrophysics Data System (ADS)

    Mansy, Hansen A.; Royston, Thomas J.; Balk, Robert A.; Sandler, Richard H.

    2003-04-01

    This study aims at investigating the feasibility of using low-frequency (<2000 Hz) acoustic methods for medical diagnosis. Several candidate methods of pneumothorax detection were tested in dogs. In the first approach, broadband acoustic signals were introduced into the trachea during end-expiration and transmitted waves were measured at the chest surface. Pneumothorax was found to consistently decrease pulmonary acoustic transmission in the 200-1200-Hz frequency band, while less change was observed at lower frequencies (p<0.0001). The ratio of acoustic energy between low (<220 Hz) and mid (550-770 Hz) frequency bands was significantly different in the control (healthy) and pneumothorax states (p<0.0001). The second approach measured breath sounds in the absence of an external acoustic input. Pneumothorax was found to be associated with a preferential reduction of sound amplitude in the 200- to 700-Hz range, and a decrease of sound amplitude variation (in the 300 to 600-Hz band) during the respiration cycle (p<0.01 for each). Finally, chest percussion was implemented. Pneumothorax changed the frequency and decay rate of percussive sounds. These results imply that certain medical conditions may be reliably detected using appropriate acoustic measurements and analysis. [Work supported by NIH/NHLBI #R44HL61108.

  14. Ocean acoustic reverberation tomography.

    PubMed

    Dunn, Robert A

    2015-12-01

    Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean bottom seismographs is a common technique for exploring earth structure beneath the oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. For surveys with a small receiver spacing (e.g., <10 km), the acoustic wave field densely samples properties of the water column over the width of the receiver array. A method, referred to as ocean acoustic reverberation tomography, is developed that uses the travel times of direct and reflected waves to image ocean acoustic structure. Reverberation tomography offers an alternative approach for determining the structure of the oceans and advancing the understanding of ocean heat content and mixing processes. The technique has the potential for revealing small-scale ocean thermal structure over the entire vertical height of the water column and along long survey profiles or across three-dimensional volumes of the ocean. For realistic experimental geometries and data noise levels, the method can produce images of ocean sound speed on a smaller scale than traditional acoustic tomography. PMID:26723303

  15. 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

  16. Anisotropic Swirling Surface Acoustic Waves from Inverse Filtering for On-Chip Generation of Acoustic Vortices

    NASA Astrophysics Data System (ADS)

    Riaud, Antoine; Thomas, Jean-Louis; Charron, Eric; Bussonnière, Adrien; Bou Matar, Olivier; Baudoin, Michael

    2015-09-01

    From radio-electronics signal analysis to biological sample actuation, surface acoustic waves (SAWs) are involved in a multitude of modern devices. However, only the most simple standing or progressive waves such as plane and focused waves have been explored so far. In this paper, we expand the SAW toolbox with a wave family named "swirling surface acoustic waves" which are the 2D anisotropic analogue of bulk acoustic vortices. Similarly to their 3D counterpart, they appear as concentric structures of bright rings with a phase singularity in their center resulting in a central dark spot. After the rigorous mathematical definition of these waves, we synthesize them experimentally through the inverse filtering technique revisited for surface waves. For this purpose, we design a setup combining arrays of interdigitated transducers and a multichannel electronic that enables one to synthesize any prescribed wave field compatible with the anisotropy of the substrate in a region called the "acoustic scene." This work opens prospects for the design of integrated acoustic vortex generators for on-chip selective acoustic tweezing.

  17. Unifying Theory of Low-Energy Nuclear Reaction and Transmutation Processes in Deuterated/hydrogenated Metals, Acoustic Cavitation, Glow Discharge, and Deuteron Beam Experiments

    NASA Astrophysics Data System (ADS)

    Kim, Yeong E.; Zubarev, Alexander L.

    The most basic theoretical challenge for understanding low-energy nuclear reaction (LENR) and transmutation reaction (LETR) in condensed matters is to find mechanisms by which the large Coulomb barrier between fusing nuclei can be overcome. A unifying theory of LENR and LETR has been developed to provide possible mechanisms for the LENR and LETR processes in matters based on high-density nano-scale and micro-scale quantum plasmas. It is shown that recently developed theoretical models based on Bose-Einstein Fusion (BEF) mechanism and Quantum Plasma Nuclear Fusion (QPNF) mechanism are applicable to the results of many different types of LENR and LETR experiments.

  18. Virtual acoustic displays

    NASA Technical Reports Server (NTRS)

    Wenzel, Elizabeth M.

    1991-01-01

    A 3D auditory display can potentially enhance information transfer by combining directional and iconic information in a quite naturalistic representation of dynamic objects in the interface. Another aspect of auditory spatial clues is that, in conjunction with other modalities, it can act as a potentiator of information in the display. For example, visual and auditory cues together can reinforce the information content of the display and provide a greater sense of presence or realism in a manner not readily achievable by either modality alone. This phenomenon will be particularly useful in telepresence applications, such as advanced teleconferencing environments, shared electronic workspaces, and monitoring telerobotic activities in remote or hazardous situations. Thus, the combination of direct spatial cues with good principles of iconic design could provide an extremely powerful and information-rich display which is also quite easy to use. An alternative approach, recently developed at ARC, generates externalized, 3D sound cues over headphones in realtime using digital signal processing. Here, the synthesis technique involves the digital generation of stimuli using Head-Related Transfer Functions (HRTF's) measured in the two ear-canals of individual subjects. Other similar approaches include an analog system developed by Loomis, et. al., (1990) and digital systems which make use of transforms derived from normative mannikins and simulations of room acoustics. Such an interface also requires the careful psychophysical evaluation of listener's ability to accurately localize the virtual or synthetic sound sources. From an applied standpoint, measurement of each potential listener's HRTF's may not be possible in practice. For experienced listeners, localization performance was only slightly degraded compared to a subject's inherent ability. Alternatively, even inexperienced listeners may be able to adapt to a particular set of HRTF's as long as they provide adequate

  19. 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

  20. 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.

  1. Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  2. Scaling and dimensional analysis of acoustic streaming jets

    SciTech Connect

    Moudjed, B.; Botton, V.; Henry, D.; Ben Hadid, H.

    2014-09-15

    This paper focuses on acoustic streaming free jets. This is to say that progressive acoustic waves are used to generate a steady flow far from any wall. The derivation of the governing equations under the form of a nonlinear hydrodynamics problem coupled with an acoustic propagation problem is made on the basis of a time scale discrimination approach. This approach is preferred to the usually invoked amplitude perturbations expansion since it is consistent with experimental observations of acoustic streaming flows featuring hydrodynamic nonlinearities and turbulence. Experimental results obtained with a plane transducer in water are also presented together with a review of the former experimental investigations using similar configurations. A comparison of the shape of the acoustic field with the shape of the velocity field shows that diffraction is a key ingredient in the problem though it is rarely accounted for in the literature. A scaling analysis is made and leads to two scaling laws for the typical velocity level in acoustic streaming free jets; these are both observed in our setup and in former studies by other teams. We also perform a dimensional analysis of this problem: a set of seven dimensionless groups is required to describe a typical acoustic experiment. We find that a full similarity is usually not possible between two acoustic streaming experiments featuring different fluids. We then choose to relax the similarity with respect to sound attenuation and to focus on the case of a scaled water experiment representing an acoustic streaming application in liquid metals, in particular, in liquid silicon and in liquid sodium. We show that small acoustic powers can yield relatively high Reynolds numbers and velocity levels; this could be a virtue for heat and mass transfer applications, but a drawback for ultrasonic velocimetry.

  3. Acoustic and Categorical Dissimilarity of Musical Timbre: Evidence from Asymmetries Between Acoustic and Chimeric Sounds

    PubMed Central

    Siedenburg, Kai; Jones-Mollerup, Kiray; McAdams, Stephen

    2016-01-01

    This paper investigates the role of acoustic and categorical information in timbre dissimilarity ratings. Using a Gammatone-filterbank-based sound transformation, we created tones that were rated as less familiar than recorded tones from orchestral instruments and that were harder to associate with an unambiguous sound source (Experiment 1). A subset of transformed tones, a set of orchestral recordings, and a mixed set were then rated on pairwise dissimilarity (Experiment 2A). We observed that recorded instrument timbres clustered into subsets that distinguished timbres according to acoustic and categorical properties. For the subset of cross-category comparisons in the mixed set, we observed asymmetries in the distribution of ratings, as well as a stark decay of inter-rater agreement. These effects were replicated in a more robust within-subjects design (Experiment 2B) and cannot be explained by acoustic factors alone. We finally introduced a novel model of timbre dissimilarity based on partial least-squares regression that compared the contributions of both acoustic and categorical timbre descriptors. The best model fit (R2 = 0.88) was achieved when both types of descriptors were taken into account. These findings are interpreted as evidence for an interplay of acoustic and categorical information in timbre dissimilarity perception. PMID:26779086

  4. Acoustic and Categorical Dissimilarity of Musical Timbre: Evidence from Asymmetries Between Acoustic and Chimeric Sounds.

    PubMed

    Siedenburg, Kai; Jones-Mollerup, Kiray; McAdams, Stephen

    2015-01-01

    This paper investigates the role of acoustic and categorical information in timbre dissimilarity ratings. Using a Gammatone-filterbank-based sound transformation, we created tones that were rated as less familiar than recorded tones from orchestral instruments and that were harder to associate with an unambiguous sound source (Experiment 1). A subset of transformed tones, a set of orchestral recordings, and a mixed set were then rated on pairwise dissimilarity (Experiment 2A). We observed that recorded instrument timbres clustered into subsets that distinguished timbres according to acoustic and categorical properties. For the subset of cross-category comparisons in the mixed set, we observed asymmetries in the distribution of ratings, as well as a stark decay of inter-rater agreement. These effects were replicated in a more robust within-subjects design (Experiment 2B) and cannot be explained by acoustic factors alone. We finally introduced a novel model of timbre dissimilarity based on partial least-squares regression that compared the contributions of both acoustic and categorical timbre descriptors. The best model fit (R (2) = 0.88) was achieved when both types of descriptors were taken into account. These findings are interpreted as evidence for an interplay of acoustic and categorical information in timbre dissimilarity perception. PMID:26779086

  5. Perception of recorded singing voice quality and expertise: cognitive linguistics and acoustic approaches.

    PubMed

    Morange, Séverine; Dubois, Danièle; Fontaine, Jean-Marc

    2010-07-01

    The objective of the present pluridisciplinary study was to contribute to determine how a diversity of audience differently appreciates several versions resulting from different "restoration" treatments of one single original lyrical recording. We present here a joint analysis coupling psychological and linguistic analyses with acoustic descriptions on a unique research object: a Caruso's piece of song diversely remastered on commercial CDs. Thirty-two subjects were selected contrasted on age ("younger than 30 years" and "older than 60 years") related with their different experience of earlier technical recording devices (rendering through devices such as radio, 78rpm records, CD...) and on expertise concerning musical acoustics (acousticians and/or musicians vs ordinary music lovers). Eleven excerpts of reediting of an opera record interpreted by Caruso were selected from what could found on the market. The listening protocol involved a free categorization task and the selection of excerpts on preference judgments. Each task involved subjects' free commentaries about their choices as a joint output from psychological processing. A cluster analysis scaffold by a psycholinguistic processing of the verbal comments of the categories allowed to identify both commonalities and differences in groupings excerpts by the different groups of the subjects, along a diversity of criteria, varying according to age and expertise. Each excerpt can therefore be characterized both according to psychological and to acoustic criteria. This study has enabled us to develop the idea that a lyric voice is a multifaced object (cultural, esthetic, technical, physical), acoustic parameters being linked to the various sensory experiences and expertises of appraisers. Such pluridisciplinary research and the coupling of the correlated multiplicity of methodologies we developed acknowledge for a better understanding of listening practices and music-lover assessments here concerned with a

  6. Measuring acoustic habitats

    PubMed Central

    Merchant, Nathan D; Fristrup, Kurt M; Johnson, Mark P; Tyack, Peter L; Witt, Matthew J; Blondel, Philippe; Parks, Susan E

    2015-01-01

    1. Many organisms depend on sound for communication, predator/prey detection and navigation. The acoustic environment can therefore play an important role in ecosystem dynamics and evolution. A growing number of studies are documenting acoustic habitats and their influences on animal development, behaviour, physiology and spatial ecology, which has led to increasing demand for passive acoustic monitoring (PAM) expertise in the life sciences. However, as yet, there has been no synthesis of data processing methods for acoustic habitat monitoring, which presents an unnecessary obstacle to would-be PAM analysts. 2. Here, we review the signal processing techniques needed to produce calibrated measurements of terrestrial and aquatic acoustic habitats. We include a supplemental tutorial and template computer codes in matlab and r, which give detailed guidance on how to produce calibrated spectrograms and statistical analyses of sound levels. Key metrics and terminology for the characterisation of biotic, abiotic and anthropogenic sound are covered, and their application to relevant monitoring scenarios is illustrated through example data sets. To inform study design and hardware selection, we also include an up-to-date overview of terrestrial and aquatic PAM instruments. 3. Monitoring of acoustic habitats at large spatiotemporal scales is becoming possible through recent advances in PAM technology. This will enhance our understanding of the role of sound in the spatial ecology of acoustically sensitive species and inform spatial planning to mitigate the rising influence of anthropogenic noise in these ecosystems. As we demonstrate in this work, progress in these areas will depend upon the application of consistent and appropriate PAM methodologies. PMID:25954500

  7. Acoustic Techniques for Thin Film Thickness Measurement in Semiconductor Processing

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Sanjay

    In modern semiconductor manufacturing, process monitoring and control are important issues limited at the present time by a lack of sensors and instrumentation capable of measuring process parameters like film thickness. In order to address this problem, two novel systems for thin film thickness measurement in semiconductor processing based upon contacting acoustic techniques have been developed. Both of these systems couple acoustic energy into the wafer via a nondestructive Hertzian contact and achieve high resolution by exciting and receiving ultrasonic signals from a ZnO transducer with microwave frequency electronics. The basic physical mechanism for film thickness determination is to analyze reflected waves due to acoustic impedance mismatches between various material layers on a silicon substrate. The first system requires frontside contacting of a sapphire buffer rod to an opaque film deposited on a silicon wafer and involves the use of broadband, high frequency pulse-echo electronics in the 0.5-5 GHz range. With this system, ex-situ measurements of aluminum and gold thin films on a silicon substrate have been done in the 0.25-2.5 mum. range with 3-6% accuracy as compared to surface profilometer measurements. Possible applications for this system include using it as a post -deposition process monitor, generating film thickness contour maps, or examining multilayer structures. The second system requires backside contacting of a sapphire buffer rod to a silicon wafer, which is in a vacuum station, and involves monitoring the changes in phase of CW 1-2 GHz acoustic waves as a function of frontside film growth. Using this technique, in-situ indium and aluminum film thickness monitoring has been done in both evaporator and sputtering environments with a resolution of 40 A. Temperature experiments in an oven have shown a resolution of 0.05 K for the sapphire buffer rod. Finally, multistep processing has been done and a multilayer film structure has been measured

  8. The Effects of Student Involvement and College Environment on Students' Learning and Living Experience at World-Class Research Universities in China: A Comparative Case Study of the University of Hong Kong (HKU) and Shanghai Jiao Tong University (SJTU)

    ERIC Educational Resources Information Center

    Chan, Roy Yew-Hung

    2011-01-01

    This comparative research examined the effects of student involvement and college environment on students' learning and living experience delivered by two aspiring world-class universities in Hong Kong and Shanghai. Few studies have shown how the levels of student involvement and college environment can benefit students at world-class institution.…

  9. Estimating animal population density using passive acoustics

    PubMed Central

    Marques, Tiago A; Thomas, Len; Martin, Stephen W; Mellinger, David K; Ward, Jessica A; Moretti, David J; Harris, Danielle; Tyack, Peter L

    2013-01-01

    Reliable estimation of the size or density of wild animal populations is very important for effective wildlife management, conservation and ecology. Currently, the most widely used methods for obtaining such estimates involve either sighting animals from transect lines or some form of capture-recapture on marked or uniquely identifiable individuals. However, many species are difficult to sight, and cannot be easily marked or recaptured. Some of these species produce readily identifiable sounds, providing an opportunity to use passive acoustic data to estimate animal density. In addition, even for species for which other visually based methods are feasible, passive acoustic methods offer the potential for greater detection ranges in some environments (e.g. underwater or in dense forest), and hence potentially better precision. Automated data collection means that surveys can take place at times and in places where it would be too expensive or dangerous to send human observers. Here, we present an overview of animal density estimation using passive acoustic data, a relatively new and fast-developing field. We review the types of data and methodological approaches currently available to researchers and we provide a framework for acoustics-based density estimation, illustrated with examples from real-world case studies. We mention moving sensor platforms (e.g. towed acoustics), but then focus on methods involving sensors at fixed locations, particularly hydrophones to survey marine mammals, as acoustic-based density estimation research to date has been concentrated in this area. Primary among these are methods based on distance sampling and spatially explicit capture-recapture. The methods are also applicable to other aquatic and terrestrial sound-producing taxa. We conclude that, despite being in its infancy, density estimation based on passive acoustic data likely will become an important method for surveying a number of diverse taxa, such as sea mammals, fish, birds

  10. Estimating animal population density using passive acoustics.

    PubMed

    Marques, Tiago A; Thomas, Len; Martin, Stephen W; Mellinger, David K; Ward, Jessica A; Moretti, David J; Harris, Danielle; Tyack, Peter L

    2013-05-01

    Reliable estimation of the size or density of wild animal populations is very important for effective wildlife management, conservation and ecology. Currently, the most widely used methods for obtaining such estimates involve either sighting animals from transect lines or some form of capture-recapture on marked or uniquely identifiable individuals. However, many species are difficult to sight, and cannot be easily marked or recaptured. Some of these species produce readily identifiable sounds, providing an opportunity to use passive acoustic data to estimate animal density. In addition, even for species for which other visually based methods are feasible, passive acoustic methods offer the potential for greater detection ranges in some environments (e.g. underwater or in dense forest), and hence potentially better precision. Automated data collection means that surveys can take place at times and in places where it would be too expensive or dangerous to send human observers. Here, we present an overview of animal density estimation using passive acoustic data, a relatively new and fast-developing field. We review the types of data and methodological approaches currently available to researchers and we provide a framework for acoustics-based density estimation, illustrated with examples from real-world case studies. We mention moving sensor platforms (e.g. towed acoustics), but then focus on methods involving sensors at fixed locations, particularly hydrophones to survey marine mammals, as acoustic-based density estimation research to date has been concentrated in this area. Primary among these are methods based on distance sampling and spatially explicit capture-recapture. The methods are also applicable to other aquatic and terrestrial sound-producing taxa. We conclude that, despite being in its infancy, density estimation based on passive acoustic data likely will become an important method for surveying a number of diverse taxa, such as sea mammals, fish, birds

  11. Job Involvement of Teachers.

    ERIC Educational Resources Information Center

    Knoop, Robert

    This study investigated the relationship between job involvement and three sets of variables: nine personal (age, sex, marital status, education, overall experience, nonteaching experience, present school experience, income, and locus of control), three structural (size of school, location of school, and hierarchical position), and eight job…

  12. A time domain sampling method for inverse acoustic scattering problems

    NASA Astrophysics Data System (ADS)

    Guo, Yukun; Hömberg, Dietmar; Hu, Guanghui; Li, Jingzhi; Liu, Hongyu

    2016-06-01

    This work concerns the inverse scattering problems of imaging unknown/inaccessible scatterers by transient acoustic near-field measurements. Based on the analysis of the migration method, we propose efficient and effective sampling schemes for imaging small and extended scatterers from knowledge of time-dependent scattered data due to incident impulsive point sources. Though the inverse scattering problems are known to be nonlinear and ill-posed, the proposed imaging algorithms are totally "direct" involving only integral calculations on the measurement surface. Theoretical justifications are presented and numerical experiments are conducted to demonstrate the effectiveness and robustness of our methods. In particular, the proposed static imaging functionals enhance the performance of the total focusing method (TFM) and the dynamic imaging functionals show analogous behavior to the time reversal inversion but without solving time-dependent wave equations.

  13. Dynamic performance of dielectric elastomers utilized as acoustic actuators

    NASA Astrophysics Data System (ADS)

    Hochradel, K.; Rupitsch, S. J.; Sutor, A.; Lerch, R.; Vu, D. K.; Steinmann, P.

    2012-06-01

    We report on the frequency dependent behavior of dielectric elastomer actuators (DEA). The introduced smart material actuators consist of 3M™'s elastomer VHB™4905 (9469) and a compliant, sputtered copper electrode on each side. The presented experiments on these compounds contain the active tuning of their resonance frequency and their application as acoustic actuators. We are able to decrease the membranes' eigenfrequency by 30% with an electrical offset potential. Alternatively, if an alternating signal is applied, sound pressure levels up to 130 dB in an enclosed volume of 28 ccm are achieved. In order to verify the results, a numerical simulation is introduced incorporating the two physical fields involved: electrical and mechanical.

  14. Arbitrary amplitude quantum dust ion-acoustic solitary waves

    SciTech Connect

    Tribeche, Mouloud; Ghebache, Siham; Aoutou, Kamel; Zerguini, Taha Houssine

    2008-03-15

    The one-dimensional quantum hydrodynamic model for a three-species quantum plasma is used to study the quantum counterpart of the well known dust ion-acoustic (DIA) wave. Two cases of physical interest are investigated, namely positive and negative dust charge. It is shown that only rarefactive solitary potentials associated with nonlinear quantum DIA (QDIA) waves involving electron density deeps can exist. The QDIA soliton experiences a spreading and the quantum effects tend to make it wider. Under certain conditions, the soliton enlarges and its pulse shape evolves into a broad central flat-bottomed (or table-bottomed) soliton as a limiting-amplitude member of the QDIA soliton family. Linear stability analysis as well as quasineutral solutions are succinctly outlined. The investigation could be of relevance to astrophysical quantum dusty plasmas.

  15. Soft 3D acoustic metamaterial with negative index.

    PubMed

    Brunet, Thomas; Merlin, Aurore; Mascaro, Benoit; Zimny, Kevin; Leng, Jacques; Poncelet, Olivier; Aristégui, Christophe; Mondain-Monval, Olivier

    2015-04-01

    Many efforts have been devoted to the design and achievement of negative-refractive-index metamaterials since the 2000s. One of the challenges at present is to extend that field beyond electromagnetism by realizing three-dimensional (3D) media with negative acoustic indices. We report a new class of locally resonant ultrasonic metafluids consisting of a concentrated suspension of macroporous microbeads engineered using soft-matter techniques. The propagation of Gaussian pulses within these random distributions of 'ultra-slow' Mie resonators is investigated through in situ ultrasonic experiments. The real part of the acoustic index is shown to be negative (up to almost - 1) over broad frequency bandwidths, depending on the volume fraction of the microbeads as predicted by multiple-scattering calculations. These soft 3D acoustic metamaterials open the way for key applications such as sub-wavelength imaging and transformation acoustics, which require the production of acoustic devices with negative or zero-valued indices. PMID:25502100

  16. Laser-induced acoustic imaging of underground objects

    NASA Astrophysics Data System (ADS)

    Li, Wen; DiMarzio, Charles A.; McKnight, Stephen W.; Sauermann, Gerhard O.; Miller, Eric L.

    1999-02-01

    This paper introduces a new demining technique based on the photo-acoustic interaction, together with results from photo- acoustic experiments. We have buried different types of targets (metal, rubber and plastic) in different media (sand, soil and water) and imaged them by measuring reflection of acoustic waves generated by irradiation with a CO2 laser. Research has been focused on the signal acquisition and signal processing. A deconvolution method using Wiener filters is utilized in data processing. Using a uniform spatial distribution of laser pulses at the ground's surface, we obtained 3D images of buried objects. The images give us a clear representation of the shapes of the underground objects. The quality of the images depends on the mismatch of acoustic impedance of the buried objects, the bandwidth and center frequency of the acoustic sensors and the selection of filter functions.

  17. Selective optical generation of a coherent acoustic nanocavity mode

    NASA Astrophysics Data System (ADS)

    Pascual Winter, M. F.; Rozas, G.; Jusserand, B.; Perrin, B.; Fainstein, A.; Vaccaro, P. O.; Saravanan, S.

    2007-04-01

    We report the first experimental evidence of selective generation of a confined acoustic mode in a Ga0.85In0.15As nanocavity enclosed by two Ga0.85In0.15As/AlAs phonon Bragg mirrors. Femtosecond pump-probe experiments reveal the generation of a cavity mode within the acoustic mini-gap of the mirrors, in addition to their folded acoustic modes. Selective generation of the confined mode alone is achievable for certain energies below the absorption of the quantum wells in the phonon mirrors. These energies are experimentally identified with the cavity spacer electronic transitions. The amplitude of the acoustic nanocavity mode can be controlled by detuning the excitation from the spacer transitions. The present work finds a direct interest in the seek of monochromatic MHz-THz acoustic sources.

  18. 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.

  19. Scanning Tomographic Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Wade, G.; Meyyappan, A.

    1988-07-01

    The technology for "seeing" with sound has an important and interesting history. Some of nature's creatures have been using sound waves for many millenia to image otherwise unobservable objects. The human species, lacking this natural ability, have overcome this deficiency by developing several different ultrasonic imaging techniques. acoustic microscopy is one such technique, which produces high resolution images of detailed structure of small objects in a non-destructive fashion. Two types of acoustic microscopes have evolved for industrial exploitation. They are the scanning laser acoustic microscope (SLAM) and the scanning acoustic microscope (SAM). In this paper, we review the principles of SLAM and describe how we use elements of SLAM to realize the scanning tomographic acoustic microscope (STAM). We describe the data acquisition process and the image reconstruction procedure. We also describe techniques to obtain projection data from different angles of wave incidence enabling us to reconstruct different planes of a complex specimen tomo-graphically. Our experimental results show that STAM is capable of producing high-quality high-resolution subsurface images.

  20. Probing mechanical properties of liposomes using acoustic sensors.

    PubMed

    Melzak, Kathryn A; Bender, Florian; Tsortos, Achilleas; Gizeli, Electra

    2008-08-19

    Acoustic devices were employed to characterize variations in the mechanical properties (density and viscoelasticity) of liposomes composed of 1-oleoyl-2-palmitoyl- sn-glycero-3-phosphocholine (POPC) and cholesterol. Liposome properties were modified in three ways. In some experiments, the POPC/cholesterol ratio was varied prior to deposition on the device surface. Alternatively, the ratio was changed in situ via either insertion of cholesterol or removal of cholesterol with beta-cyclodextrin. This was done for liposomes adsorbed directly on the device surface and for liposomes attached via a biotin-terminated poly(ethylene glycol) linker. The acoustic measurements make use of two simultaneous time-resolved signals: one signal is related to the velocity of the acoustic wave, while the second is related to dissipation of acoustic energy. Together, they provide information not only about the mass (or density) of the probed medium but also about its viscoelastic properties. The cholesterol-induced increase in the surface density of the lipid bilayer was indeed observed in the acoustic data, but the resulting change in signal was larger than expected from the change in surface density. In addition, increasing the bilayer resistance to stretching was found to lead to a greater dissipation of the acoustic energy. The acoustic response is assessed in terms of the possible distortions of the liposomes and the known effects of cholesterol on the mechanical properties of the lipid bilayer that encloses the aqueous core of the liposome. To aid the interpretation of the acoustic response, it is discussed how the above changes in the lipid bilayer will affect the effective viscoelastic properties of the entire liposome/solvent film on the scale of the acoustic wavelength. It was found that the acoustic device is very sensitive to the mechanical properties of lipid vesicles; the response of the acoustic device is explained, and the basic underlying mechanisms of interaction are

  1. NASA Rat Acoustic Tolerance Test 1994-1995: 8 kHz, 16 kHz, 32 kHz Experiments

    NASA Technical Reports Server (NTRS)

    Mele, Gary D.; Holley, Daniel C.; Naidu, Sujata

    1996-01-01

    Adult male Sprague-Dawley rats were exposed to chronic applied sound (74 to 79 dB, SPL) with octave band center frequencies of either 8, 16 or 32 kHz for up to 60 days. Control cages had ambient sound levels of about 62 dB (SPL). Groups of rats (test vs. control; N=9 per group) were euthanized after 0. 5. 14, 30, and 60 days. On each euthanasia day, objective evaluation of their physiology and behavior was performed using a Stress Assessment Battery (SAB) of measures. In addition, rat hearing was assessed using the brain stem auditory evoked potential (BAER) method after 60 days of exposure. No statistically significant differences in mean daily food use could be attributed to the presence of the applied test sound. Test rats used 5% more water than control rats. In the 8 kHz and 32 kHz tests this amount was statistically significant(P less than .05). This is a minor difference of questionable physiological significance. However, it may be an indication of a small reaction to the constant applied sound. Across all test frequencies, day 5 test rats had 6% larger spleens than control rats. No other body or organ weight differences were found to be statistically significant with respect to the application of sound. This spleen effect may be a transient adaptive process related to adaptation to the constant applied noise. No significant test effect on differential white blood cell counts could be demonstrated. One group demonstrated a low eosinophil count (16 kHz experiment, day 14 test group). However this was highly suspect. Across all test frequencies studied, day 5 test rats had 17% fewer total leukocytes than day 5 control rats. Sound exposed test rats exhibited 44% lower plasma corticosterone concentrations than did control rats. Note that the plasma corticosterone concentration was lower in the sound exposed test animals than the control animals in every instance (frequency exposure and number of days exposed).

  2. An overview of acoustic telemetry

    SciTech Connect

    Drumheller, D.S.

    1992-01-01

    Acoustic telemetry has been a dream of the drilling industry for the past 50 years. It offers the promise of data rates which are one-hundred times greater than existing technology. Such a system would open the door to true logging-while-drilling technology and bring enormous profits to its developers. The basic idea is to produce an encoded sound wave at the bottom of the well, let it propagate up the steel drillpipe, and extract the data from the signal at the surface. Unfortunately, substantial difficulties arise. The first difficult problem is to produce the sound wave. Since the most promising transmission wavelengths are about 20 feet, normal transducer efficiencies are quire low. Compounding this problem is the structural complexity of the bottomhole assembly and drillstring. For example, the acoustic impedance of the drillstring changes every 30 feet and produces an unusual scattering pattern in the acoustic transmission. This scattering pattern causes distortion of the signal and is often confused with signal attenuation. These problems are not intractable. Recent work has demonstrated that broad frequency bands exist which are capable of transmitting data at rates up to 100 bits per second. Our work has also identified the mechanism which is responsible for the observed anomalies in the patterns of signal attenuation. Furthermore in the past few years a body of experience has been developed in designing more efficient transducers for application to metal waveguides. The direction of future work is clear. New transducer designs which are more efficient and compatible with existing downhole power supplies need to be built and tested; existing field test data need to be analyzed for transmission bandwidth and attenuation; and the new and less expensive methods of collecting data on transmission path quality need to be incorporated into this effort. 11 refs.

  3. Measurement of complex acoustic intensity in an acoustic waveguide.

    PubMed

    Duan, Wenbo; Kirby, Ray; Prisutova, Jevgenija; Horoshenkov, Kirill V

    2013-11-01

    Acoustic intensity is normally treated as a real quantity, but in recent years, many articles have appeared in which intensity is treated as a complex quantity where the real (active) part is related to local mean energy flow and the imaginary (reactive) part to local oscillatory transport of energy. This offers the potential to recover additional information about a sound field and then to relate this to the properties of the sound source and the environment that surrounds it. However, this approach is applicable only to multi-modal sound fields, which places significant demands on the accuracy of the intensity measurements. Accordingly, this article investigates the accuracy of complex intensity measurements obtained using a tri-axial Microflown intensity probe by comparing measurement and prediction for sound propagation in an open flanged pipe. Under plane wave conditions, comparison between prediction and experiment reveals good agreement, but when a higher order mode is present, the reactive intensity field becomes complicated and agreement is less successful. It is concluded that the potential application of complex intensity as a diagnostic tool is limited by difficulties in measuring reactive intensity in complex sound fields when using current state of the art acoustic instrumentation. PMID:24180778

  4. ACOUSTICS IN ARCHITECTURAL DESIGN, AN ANNOTATED BIBLIOGRAPHY ON ARCHITECTURAL ACOUSTICS.

    ERIC Educational Resources Information Center

    DOELLE, LESLIE L.

    THE PURPOSE OF THIS ANNOTATED BIBLIOGRAPHY ON ARCHITECTURAL ACOUSTICS WAS--(1) TO COMPILE A CLASSIFIED BIBLIOGRAPHY, INCLUDING MOST OF THOSE PUBLICATIONS ON ARCHITECTURAL ACOUSTICS, PUBLISHED IN ENGLISH, FRENCH, AND GERMAN WHICH CAN SUPPLY A USEFUL AND UP-TO-DATE SOURCE OF INFORMATION FOR THOSE ENCOUNTERING ANY ARCHITECTURAL-ACOUSTIC DESIGN…

  5. Acoustic energy shaping

    NASA Technical Reports Server (NTRS)

    Wang, T. G.; Elleman, D. D. (Inventor)

    1977-01-01

    A suspended mass is shaped by melting all or a selected portion of the mass and applying acoustic energy in varying amounts to different portions of the mass. In one technique for forming an optical waveguide slug, a mass of oval section is suspended and only a portion along the middle of the cross-section is heated to a largely fluid consistency. Acoustic energy is applied to opposite edges of the oval mass to press the unheated opposite edge portions together so as to form bulges at the middle of the mass. In another technique for forming a ribbon of silicon for constructing solar cells, a cylindrical thread of silicon is drawn from a molten mass of silicon, and acoustic energy is applied to opposite sides of the molten thread to flatten it into a ribbon.

  6. Passive broadband acoustic thermometry

    NASA Astrophysics Data System (ADS)

    Anosov, A. A.; Belyaev, R. V.; Klin'shov, V. V.; Mansfel'd, A. D.; Subochev, P. V.

    2016-04-01

    The 1D internal (core) temperature profiles for the model object (plasticine) and the human hand are reconstructed using the passive acoustothermometric broadband probing data. Thermal acoustic radiation is detected by a broadband (0.8-3.5 MHz) acoustic radiometer. The temperature distribution is reconstructed using a priori information corresponding to the experimental conditions. The temperature distribution for the heated model object is assumed to be monotonic. For the hand, we assume that the temperature distribution satisfies the heat-conduction equation taking into account the blood flow. The average error of reconstruction determined for plasticine from the results of independent temperature measurements is 0.6 K for a measuring time of 25 s. The reconstructed value of the core temperature of the hand (36°C) generally corresponds to physiological data. The obtained results make it possible to use passive broadband acoustic probing for measuring the core temperatures in medical procedures associated with heating of human organism tissues.

  7. Surface Acoustic Wave Microfluidics

    NASA Astrophysics Data System (ADS)

    Yeo, Leslie Y.; Friend, James R.

    2014-01-01

    Fluid manipulations at the microscale and beyond are powerfully enabled through the use of 10-1,000-MHz acoustic waves. A superior alternative in many cases to other microfluidic actuation techniques, such high-frequency acoustics is almost universally produced by surface acoustic wave devices that employ electromechanical transduction in wafer-scale or thin-film piezoelectric media to generate the kinetic energy needed to transport and manipulate fluids placed in adjacent microfluidic structures. These waves are responsible for a diverse range of complex fluid transport phenomena - from interfacial fluid vibration and drop and confined fluid transport to jetting and atomization - underlying a flourishing research literature spanning fundamental fluid physics to chip-scale engineering applications. We highlight some of this literature to provide the reader with a historical basis, routes for more detailed study, and an impression of the field's future directions.

  8. Latticed pentamode acoustic cloak

    PubMed Central

    Chen, Yi; Liu, Xiaoning; Hu, Gengkai

    2015-01-01

    We report in this work a practical design of pentamode acoustic cloak with microstructure. The proposed cloak is assembled by pentamode lattice made of a single-phase solid material. The function of rerouting acoustic wave round an obstacle has been demonstrated numerically. It is also revealed that shear related resonance due to weak shear resistance in practical pentamode lattices punctures broadband feature predicted based on ideal pentamode cloak. As a consequence, the latticed pentamode cloak can only conceal the obstacle in segmented frequency ranges. We have also shown that the shear resonance can be largely reduced by introducing material damping, and an improved broadband performance can be achieved. These works pave the way for experimental demonstration of pentamode acoustic cloak. PMID:26503821

  9. Experiments with Ultrasonic Transducers.

    ERIC Educational Resources Information Center

    Greenslade, Thomas R., Jr.

    1994-01-01

    Discusses the use of 40 kHz ultrasonic transducers to study wave phenomena. Determines that the resulting wavelength of 9 mm allows acoustic experiments to be performed on a tabletop. Includes transducer characteristics and activities on speed of sound, reflection, double- and single-slit diffraction, standing waves, acoustical zone plate, and…

  10. The Japanese containerless experiments

    NASA Technical Reports Server (NTRS)

    Azuma, Hisao

    1990-01-01

    There are three sets of Japanese containerless experiments. The first is Drop dynamics research. It consists of acoustic levitation and large amplitude drop oscillation. The second is Optical materials processing in an acoustic levitation furnace. And the third is Electrostatic levitator development by two different Japanese companies.

  11. Measuring two-phase particle flux with a multi-frequency acoustic Doppler profiler.

    PubMed

    Wilson, Gregory W; Hay, Alex E

    2015-12-01

    A methodology is developed and tested for simultaneously extracting time-resolved one-dimensional profiles of the mass-concentration and velocity of two different particle types in a mixed suspension, using a multi-frequency pulse-to-pulse coherent Doppler instrument. The technique involves inversion of a model for frequency-dependent acoustic backscatter amplitude and phase. Results are presented from a laboratory settling column experiment, measuring a mixture of polystyrene beads (slowly-settling, strongly-scattering) and glass beads (quickly-settling, weakly-scattering) in a vertical pipe section. PMID:26723335

  12. Transmission Characteristics of Primate Vocalizations: Implications for Acoustic Analyses

    PubMed Central

    Maciej, Peter; Fischer, Julia; Hammerschmidt, Kurt

    2011-01-01

    Acoustic analyses have become a staple method in field studies of animal vocal communication, with nearly all investigations using computer-based approaches to extract specific features from sounds. Various algorithms can be used to extract acoustic variables that may then be related to variables such as individual identity, context or reproductive state. Habitat structure and recording conditions, however, have strong effects on the acoustic structure of sound signals. The purpose of this study was to identify which acoustic parameters reliably describe features of propagated sounds. We conducted broadcast experiments and examined the influence of habitat type, transmission height, and re-recording distance on the validity (deviation from the original sound) and reliability (variation within identical recording conditions) of acoustic features of different primate call types. Validity and reliability varied independently of each other in relation to habitat, transmission height, and re-recording distance, and depended strongly on the call type. The smallest deviations from the original sounds were obtained by a visually-controlled calculation of the fundamental frequency. Start- and end parameters of a sound were most susceptible to degradation in the environment. Because the recording conditions can have appreciable effects on acoustic parameters, it is advisable to validate the extraction method of acoustic variables from recordings over longer distances before using them in acoustic analyses. PMID:21829682

  13. A New Wave of Acoustics.

    ERIC Educational Resources Information Center

    Beyer, Robert

    1981-01-01

    Surveys 50 years of acoustical studies by discussing selected topics including the ear, nonlinear representations, underwater sound, acoustical diagnostics, absorption, electrolytes, phonons, magnetic interaction, and superfluidity and the five sounds. (JN)

  14. Vector Acoustic Sensors for Marine Seismic Surveys

    NASA Astrophysics Data System (ADS)

    Lindwall, D.

    2005-12-01

    Using vector acoustic sensors for marine seismic and geo-acoustic surveys instead of the usual scalar hydrophones allows for acquiring a 3-D survey with the instrumentation and logistics similar to current 2-D surveys. Vector acoustic sensors measure the wave direction directly without the large and cumbersome arrays that hydrophones require. This concept was tested by a scaled experiment in an acoustic water tank that has a well controlled environment with a few targets. The experiment was scaled to the size of the available water tank and the frequency limits of the sensor. The sensor consists of a three-axis accelerometer as well as a hydrophone. The sound source was a standard hydrophone driven by a short 8 kHz pulse. The sensor was suspended in a fixed location and the hydrophone was moved about the tank by a robotic arm to insonify the tank from many locations. During part of the experiment, several floats (acoustic targets) were placed in the tank at diagonal ranges of approximately one meter. The accelerometer data show the direct source wave as well as the target scattered waves and reflections from the nearby water surface, tank bottom and sides. Vector data from single shots show that the wave motion direction can be readily determined for both direct waves and scattered waves. Without resorting to the usual methods of seismic imaging, which in this case would have only been two dimensional and relied entirely on the use of a synthetic source aperture, the three-dimensional volume of the tank environment was imaged. This work was supported by the Office of Naval Research, program element 61153N.

  15. Microgravity acoustic mixing for particle cloud combustors

    NASA Technical Reports Server (NTRS)

    Pla, Frederic; Rubinstein, Robert I.

    1990-01-01

    Experimental and theoretical investigations of acoustic mixing procedures designed to uniformly distribute fuel particles in a combustion tube for application in the proposed Particle Cloud Combustion Experiment (PCCE) are described. Two acoustic mixing methods are investigated: mixing in a cylindrical tube using high frequency spinning modes generated by suitably phased, or quadrature speakers, and acoustic premixing in a sphere. Quadrature mixing leads to rapid circumferential circulation of the powder around the tube. Good mixing is observed in the circulating regions. However, because axial inhomogeneities are necessarily present in the acoustic field, this circulation does not extend throughout the tube. Simultaneous operation of the quadrature-speaker set and the axial-speaker was observed to produce considerably enhanced mixing compared to operation of the quadrature-speaker set alone. Mixing experiments using both types of speakers were free of the longitudinal powder drift observed using axial-speakers alone. Vigorous powder mixing was obtained in the sphere for many normal modes: however, in no case was the powder observed to fill the sphere entirely. Theoretical analysis indicated that mixing under steady conditions cannot fill more than a hemisphere except under very unusual conditions. Premixing in a hemisphere may be satisfactory; otherwise, complete mixing in microgravity might be possible by operating the speaker in short bursts. A general conclusion is that acoustic transients are more likely to produce good mixing than steady state conditions. The reason is that in steady conditions, flow structures like nodal planes are possible and often even unavoidable. These tend to separate the mixing region into cells across which powder cannot be transferred. In contrast, transients not only are free of such structures, they also have the characteristics, desirable for mixing, of randomness and disorder. This conclusion is corroborated by mixing

  16. High-frequency combustion instability control through acoustic modulation at the inlet boundary for liquid rocket engine applications

    NASA Astrophysics Data System (ADS)

    Bennewitz, John William

    This research investigation encompasses experimental tests demonstrating the control of a high-frequency combustion instability by acoustically modulating the propellant flow. A model rocket combustor burned gaseous oxygen and methane using a single-element, pentad-style injector. Flow conditions were established that spontaneously excited a 2430 Hz first longitudinal combustion oscillation at an amplitude up to p'/pc ≈ 6%. An acoustic speaker was placed at the base of the oxidizer supply to modulate the flow and alter the oscillatory behavior of the combustor. Two speaker modulation approaches were investigated: (1) Bands of white noise and (2) Pure sinusoidal tones. The first approach adjusted 500 Hz bands of white noise ranging from 0-500 Hz to 2000-2500 Hz, while the second implemented single-frequency signals with arbitrary phase swept from 500-2500 Hz. The results showed that above a modulation signal amplitude threshold, both approaches suppressed 95+% of the spontaneous combustion oscillation. By increasing the applied signal amplitude, a wider frequency range of instability suppression became present for these two acoustic modulation approaches. Complimentary to these experiments, a linear modal analysis was undertaken to investigate the effects of acoustic modulation at the inlet boundary on the longitudinal instability modes of a dump combustor. The modal analysis employed acoustically consistent matching conditions with a specific impedance boundary condition at the inlet to represent the acoustic modulation. From the modal analysis, a naturally unstable first longitudinal mode was predicted in the absence of acoustic modulation, consistent with the spontaneously excited 2430 Hz instability observed experimentally. Subsequently, a detailed investigation involving variation of the modulation signal from 0-2500 Hz and mean combustor temperature from 1248-1685 K demonstrated the unstable to stable transition of a 2300-2500 Hz first longitudinal mode. The

  17. Densitometry By Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Trinh, Eugene H.

    1989-01-01

    "Static" and "dynamic" methods developed for measuring mass density of acoustically levitated solid particle or liquid drop. "Static" method, unknown density of sample found by comparison with another sample of known density. "Dynamic" method practiced with or without gravitational field. Advantages over conventional density-measuring techniques: sample does not have to make contact with container or other solid surface, size and shape of samples do not affect measurement significantly, sound field does not have to be know in detail, and sample can be smaller than microliter. Detailed knowledge of acoustic field not necessary.

  18. Acoustic tooth cleaner

    NASA Technical Reports Server (NTRS)

    Heyman, J. S. (Inventor)

    1982-01-01

    An acoustic oral hygiene unit is described that uses acoustic energy to oscillate mild abrasive particles in a water suspension which is then directed in a low pressure stream onto the teeth. The oscillating abrasives scrub the teeth clean removing food particles, plaque, calculous, and other foreign material from tooth surfaces, interproximal areas, and tooth-gingiva interface more effectively than any previous technique. The relatively low power output and the basic design makes the invention safe and convenient for everyday use in the home without special training. This invention replaces all former means of home dental prophylaxis, and requires no augmentation to fulfill all requirements for daily oral hygienic care.

  19. Acoustic emission intrusion detector

    DOEpatents

    Carver, Donald W.; Whittaker, Jerry W.

    1980-01-01

    An intrusion detector is provided for detecting a forcible entry into a secured structure while minimizing false alarms. The detector uses a piezoelectric crystal transducer to sense acoustic emissions. The transducer output is amplified by a selectable gain amplifier to control the sensitivity. The rectified output of the amplifier is applied to a Schmitt trigger circuit having a preselected threshold level to provide amplitude discrimination. Timing circuitry is provided which is activated by successive pulses from the Schmitt trigger which lie within a selected time frame for frequency discrimination. Detected signals having proper amplitude and frequency trigger an alarm within the first complete cycle time of a detected acoustical disturbance signal.

  20. Acoustic bubble removal method

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Elleman, D. D.; Wang, T. G. (Inventor)

    1983-01-01

    A method is described for removing bubbles from a liquid bath such as a bath of molten glass to be used for optical elements. Larger bubbles are first removed by applying acoustic energy resonant to a bath dimension to drive the larger bubbles toward a pressure well where the bubbles can coalesce and then be more easily removed. Thereafter, submillimeter bubbles are removed by applying acoustic energy of frequencies resonant to the small bubbles to oscillate them and thereby stir liquid immediately about the bubbles to facilitate their breakup and absorption into the liquid.