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Sample records for acoustic heating

  1. Acoustically enhanced heat transport

    Energy Technology Data Exchange (ETDEWEB)

    Ang, Kar M.; Hung, Yew Mun; Tan, Ming K., E-mail: tan.ming.kwang@monash.edu [School of Engineering, Monash University Malaysia, 47500 Bandar Sunway, Selangor (Malaysia); Yeo, Leslie Y. [Micro/Nanophysics Research Laboratory, RMIT University, Melbourne, VIC 3001 (Australia); Friend, James R. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, California 92093 (United States)

    2016-01-15

    We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ∼ 10{sup 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 (ξ{sub s} ∼ 10{sup −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 (ξ{sub s} ∼ 10{sup −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{sup −8} m with 10{sup 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.

  2. Acoustically enhanced heat transport

    Science.gov (United States)

    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.

  3. Acoustic streaming with heat exchange

    Science.gov (United States)

    Gubaidullin, A. A.; Pyatkova, A. V.

    2016-10-01

    Acoustic streaming in a cylindrical cavity with heat exchange is numerically investigated. The cavity is filled with air. The boundaries of the cavity are maintained at constant temperature. The features of acoustic streaming manifesting with the decrease in the frequency of vibration in comparison with the resonant frequency are determined. The influence of the nonlinearity of process on acoustic streaming is shown. The nonlinearity is caused by the increase of the vibration amplitude.

  4. Cooling Acoustic Transcucer with Heat Pipes

    Science.gov (United States)

    2009-07-19

    pipes. [0013] Most transducer packages involve a stack of active ceramic. A Tonpilz transducer 10 in the prior art, as depicted in FIG. 1...identical or corresponding parts throughout the several views and wherein: [0023] FIG. 1 is a prior art depiction of a Tonpilz transducer design...Distribution is unlimited 20090916027 Attorney Docket No. 97001 COOLING ACOUSTIC TRANSDUCER WITH HEAT PIPES STATEMENT OF GOVERNMENT INTEREST [0001

  5. Acoustic Optimization of Automotive Exhaust Heat Thermoelectric Generator

    Science.gov (United States)

    Su, C. Q.; Ye, B. Q.; Guo, X.; Hui, P.

    2012-06-01

    The potential for thermoelectric exhaust heat recovery in vehicles has been increasing with recent advances in the efficiency of thermoelectric generators (TEGs). This study analyzes the acoustic attenuation performance of exhaust-based TEGs. The acoustic characteristics of two different thermal designs of exhaust gas heat exchanger in TEGs are discussed in terms of transmission loss and acoustic insertion loss. GT-Power simulations and bench tests on a dynamometer with a high-performance production engine are carried out. Results indicate that the acoustic attenuation of TEGs could be determined and optimized. In addition, the feasibility of integration of exhaust-based TEGs and engine mufflers into the exhaust line is tested, which can help to reduce space and improve vehicle integration.

  6. Enhancement of gas phase heat transfer by acoustic field application.

    Science.gov (United States)

    Komarov, Sergey; Hirasawa, Masahiro

    2003-06-01

    This study discusses a possibility for enhancement of heat transfer between solids and ambient gas by application of powerful acoustic fields. Experiments are carried out by using preheated Pt wires (length 0.1-0.15 m, diameter 50 and 100 micro m) positioned at the velocity antinode of a standing wave (frequency range 216-1031 Hz) or in the path of a travelling wave (frequency range 6.9-17.2 kHz). A number of experiments were conducted under conditions of gas flowing across the wire surface. Effects of sound frequency, sound strength, gas flow velocity and wire preheating temperature on the Nusselt number are examined with and without sound application. The gas phase heat transfer rate is enhanced with acoustic field strength. Higher temperatures result in a vigorous radiation from the wire surface and attenuate the effect of sound. The larger the gas flow velocity, the smaller is the effect of sound wave on heat transfer enhancement.

  7. Chromospheric heating by acoustic waves compared to radiative cooling

    CERN Document Server

    Sobotka, M; Švanda, M; Jurčák, J; del Moro, D; Berrilli, F

    2016-01-01

    Acoustic and magnetoacoustic waves are among the possible candidate mechanisms that heat the upper layers of solar atmosphere. A weak chromospheric plage near a large solar pore NOAA 11005 was observed on October 15, 2008 in the lines Fe I 617.3 nm and Ca II 853.2 nm with the Interferometric Bidimemsional Spectrometer (IBIS) attached to the Dunn Solar Telescope. Analyzing the Ca II observations with spatial and temporal resolutions of 0.4" and 52 s, the energy deposited by acoustic waves is compared with that released by radiative losses. The deposited acoustic flux is estimated from power spectra of Doppler oscillations measured in the Ca II line core. The radiative losses are calculated using a grid of seven 1D hydrostatic semi-empirical model atmospheres. The comparison shows that the spatial correlation of maps of radiative losses and acoustic flux is 72 %. In quiet chromosphere, the contribution of acoustic energy flux to radiative losses is small, only of about 15 %. In active areas with photospheric ma...

  8. Micro acoustic resonant chambers for heating/agitating/mixing (MARCHAM)

    Science.gov (United States)

    Sherrit, Stewart; Noell, Aaron C.; Fisher, Anita M.; Takano, Nobuyuki; Grunthaner, Frank

    2016-04-01

    A variety of applications require the mixing and/or heating of a slurry made from a powder/fluid mixture. One of these applications, Sub Critical Water Extraction (SCWE), is a process where water and an environmental powder sample (sieved soil, drill cuttings, etc.) are heated in a sealed chamber to temperatures greater than 200 degrees Celsius by allowing the pressure to increase, but without reaching the critical point of water. At these temperatures, the ability of water to extract organics from solid particulate increases drastically. This paper describes the modeling and experimentation on the use of an acoustic resonant chamber which is part of an amino acid detection instrument called Astrobionibbler [Noell et al. 2014, 2015]. In this instrument we use acoustics to excite a fluid- solid fines mixture in different frequency/amplitude regimes to accomplish a variety of sample processing tasks. Driving the acoustic resonant chamber at lower frequencies can create circulation patterns in the fluid and mixes the liquid and fines, while driving the chamber at higher frequencies one can agitate the fluid and powder and create a suspension. If one then drives the chamber at high amplitude at resonance heating of the slurry occurs. In the mixing and agitating cell the particle levitation force depends on the relative densities and compressibility's of the particulate and fluid and on the kinetic and potential energy densities associated with the velocity and pressure fields [Glynne-Jones, Boltryk and Hill 2012] in the cell. When heating, the piezoelectric transducer and chamber is driven at high power in resonance where the solid/fines region is modelled as an acoustic transmission line with a large loss component. In this regime, heat is pumped into the solution/fines mixture and rapidly heats the sample. We have modeled the piezoelectric transducer/chamber/ sample using Mason's equivalent circuit. In order to assess the validity of the model we have built and

  9. Geodesic acoustic mode in anisotropic plasma with heat flux

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Haijun, E-mail: hjren@ustc.edu.cn [CAS Key Laboratory of Geospace Environment and Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)

    2015-10-15

    Geodesic acoustic mode (GAM) in an anisotropic tokamak plasma is investigated in fluid approximation. The collisionless anisotropic plasma is described within the 16-momentum magnetohydrodynamic (MHD) fluid closure model, which takes into account not only the pressure anisotropy but also the anisotropic heat flux. It is shown that the GAM frequency agrees better with the kinetic result than the standard Chew-Goldberger-Low (CGL) MHD model. When zeroing the anisotropy, the 16-momentum result is identical with the kinetic one to the order of 1/q{sup 2}, while the CGL result agrees with the kinetic result only on the leading order. The discrepancies between the results of the CGL fluid model and the kinetic theory are well removed by considering the heat flux effect in the fluid approximation.

  10. Heat Transfer and Acoustic Properties of Open Cell Aluminum Foams

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The aluminum open cell foams have been prepared by the conventional precision casting method to investigate the thermal and acoustic properties. A water heating system and silencers were organized as a first step for its applications. The temperature increase between the top and bottom of the foam became larger as the cell size increased in the heat transfer measurement. Sound absorption ratio of the close cell foams was 60%-100%,whereas the open cell aluminum foam showed only 10%-20% of sound absorption at low frequency. When the prototype electric water heater manufactured by combining aluminum open cell foam with a heater was heated to 100-400℃, the highest temperature of water was in the range of 16-46℃. This suggests that there could be potential for this type of heater to be used as a commercial electric water heater. Sound silencer made with the aluminum open cell foam was applied to exit of exhaustion side at air pressure line. Sound silencing effect of open-celled aluminum foam showed that the noise level went down by introducing smaller cell size foam.

  11. Acoustic Streaming and Heat and Mass Transfer Enhancement

    Science.gov (United States)

    Trinh, E. H.; Gopinath, A.

    1996-01-01

    A second order effect associated with high intensity sound field, acoustic streaming has been historically investigated to gain a fundamental understanding of its controlling mechanisms and to apply it to practical aspects of heat and mass transfer enhancement. The objectives of this new research project are to utilize a unique experimental technique implementing ultrasonic standing waves in closed cavities to study the details of the generation of the steady-state convective streaming flows and of their interaction with the boundary of ultrasonically levitated near-spherical solid objects. The goals are to further extend the existing theoretical studies of streaming flows and sample interactions to higher streaming Reynolds number values, for larger sample size relative to the wavelength, and for a Prandtl and Nusselt numbers parameter range characteristic of both gaseous and liquid host media. Experimental studies will be conducted in support to the theoretical developments, and the crucial impact of microgravity will be to allow the neglect of natural thermal buoyancy. The direct application to heat and mass transfer in the absence of gravity will be emphasized in order to investigate a space-based experiment, but both existing and novel ground-based scientific and technological relevance will also be pursued.

  12. Pulsed Acoustic Sparker Bio-Fouling Control in Heat Transfer Equipment

    Science.gov (United States)

    2002-10-21

    10/21/2002 1 Final Report SERDP/SEED Pulsed Acoustic Sparker Bio -Fouling Control in Heat Transfer...COVERED 00-00-2002 to 00-00-2002 4. TITLE AND SUBTITLE Pulsed Acoustic Sparker Bio -Fouling Control in Heat Transfer Equipment 5a. CONTRACT...requirements. Furthermore, a sparker bio -controller would eliminate the requirements for hazardous materials storage. Sparkers also are economically

  13. Characterization of acoustic streaming and heating using synchronized infrared thermography and particle image velocimetry.

    Science.gov (United States)

    Layman, Christopher N; Sou, In Mei; Bartak, Rico; Ray, Chittaranjan; Allen, John S

    2011-09-01

    Real-time measurements of acoustic streaming velocities and surface temperature fields using synchronized particle image velocimetry and infrared thermography are reported. Measurements were conducted using a 20 kHz Langevin type acoustic horn mounted vertically in a model sonochemical reactor of either degassed water or a glycerin-water mixture. These dissipative phenomena are found to be sensitive to small variations in the medium viscosity, and a correlation between the heat flux and vorticity was determined for unsteady convective heat transfer.

  14. Flow-flame interactions causing acoustically coupled heat release fluctuations in a thermo-acoustically unstable gas turbine model combustor

    Energy Technology Data Exchange (ETDEWEB)

    Steinberg, A.M.; Boxx, I.; Stoehr, M.; Meier, W. [Institute for Combustion Technology, German Aerospace Centre (DLR), 70569 Stuttgart (Germany); Carter, C.D. [Air Force Research Laboratory, Wright-Patterson AFB, OH (United States)

    2010-12-15

    A detailed analysis of the flow-flame interactions associated with acoustically coupled heat-release rate fluctuations was performed for a 10 kW, CH{sub 4}/air, swirl stabilized flame in a gas turbine model combustor exhibiting self-excited thermo-acoustic oscillations at 308 Hz. High-speed stereoscopic particle image velocimetry, OH planar laser induced fluorescence, and OH* chemiluminescence measurements were performed at a sustained repetition rate of 5 kHz, which was sufficient to resolve the relevant combustor dynamics. Using spatio-temporal proper orthogonal decomposition, it was found that the flow-field contained several simultaneous periodic motions: the reactant flux into the combustion chamber periodically oscillated at the thermo-acoustic frequency (308 Hz), a helical precessing vortex core (PVC) circumscribed the burner nozzle at 515 Hz, and the PVC underwent axial contraction and extension at the thermo-acoustic frequency. The global heat release rate fluctuated at the thermo-acoustic frequency, while the heat release centroid circumscribed the combustor at the difference between the thermo-acoustic and PVC frequencies. Hence, the three-dimensional location of the heat release fluctuations depended on the interaction of the PVC with the flame surface. This motivated the compilation of doubly phase resolved statistics based on the phase of both the acoustic and PVC cycles, which showed highly repeatable periodic flow-flame configurations. These include flames stabilized between the inflow and inner recirculation zone, large-scale flame wrap-up by the PVC, radial deflection of the inflow by the PVC, and combustion in the outer recirculation zones. Large oscillations in the flame surface area were observed at the thermo-accoustic frequency that significantly affected the total heat-release oscillations. By filtering the instantaneous reaction layers at different scales, the importance of the various flow-flame interactions affecting the flame area was

  15. Computational study for investigating acoustic streaming and heating during acoustic hemostasis

    CERN Document Server

    Solovchuk, Maxim A; Sheu, Tony W H

    2014-01-01

    High intensity focused ultrasound (HIFU) has many applications ranging from thermal ablation of cancer to hemostasis. Although focused ultrasound can seal a bleeding site, physical mechanisms of acoustic hemostasis are not fully understood yet. To understand better the interaction between different physical mechanisms involved in hemostasis a mathematical model of acoustic hemostasis is developed. This model comprises the nonlinear Westervelt equation and the bioheat equations in tissue and blood vessel. In the three dimensional domain, the nonlinear hemodynamic equations are coupled with the acoustic and thermal equations. Convected cooling and acoustic streaming effects are incorporated in the modeling study. Several sonication angles and two wound shapes have been studied. The optimal focal point location is at the rear of the wound and the optimal angle is 45$^0$.

  16. An acoustical pump capable of significantly increasing pressure ratio of thermoacoustic heat engines

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Pressure ratio is one of the important parameters for evaluating a thermoacoustic heat engine. A so-called acoustical pump, which is capable of significantly increasing pressure ratio of a thermoacoustic heat engine, is proposed. Its operating principle is given. Also, a verification experiment is done with nitrogen gas in the energy-focused thermoacoustic heat engine, showing that the pressure ratio increased from 1.25 to 1.47.

  17. Acoustic streaming induced by ultrasonic flexural vibrations and associated enhancement of convective heat transfer.

    Science.gov (United States)

    Loh, Byoung-Gook; Hyun, Sinjae; Ro, Paul I; Kleinstreuer, Clement

    2002-02-01

    Acoustic streaming induced by ultrasonic flexural vibrations and the associated convection enhancement are investigated. Acoustic streaming pattern, streaming velocity, and associated heat transfer characteristics are experimentally observed. Moreover, analytical analysis based on Nyborg's formulation is performed along with computational fluid dynamics (CFD) simulation using a numerical solver CFX 4.3. Two distinctive acoustic streaming patterns in half-wavelength of the flexural vibrations are observed, which agree well with the theory. However, acoustic streaming velocities obtained from CFD simulation, based on the incompressible flow assumption, exceed the theoretically estimated velocity by a factor ranging from 10 to 100, depending upon the location along the beam. Both CFD simulation and analytical analysis reveal that the acoustic streaming velocity is proportional to the square of the vibration amplitude and the wavelength of the vibrating beam that decreases with the excitation frequency. It is observed that the streaming velocity decreases with the excitation frequency. Also, with an open-ended channel, a substantial increase in streaming velocity is observed from CFD simulations. Using acoustic streaming, a temperature drop of 40 degrees C with a vibration amplitude of 25 microm at 28.4 kHz is experimentally achieved.

  18. Acoustic Emission Methodology to Evaluate the Fracture Toughness in Heat Treated AISI D2 Tool Steel

    Science.gov (United States)

    Mostafavi, Sajad; Fotouhi, Mohamad; Motasemi, Abed; Ahmadi, Mehdi; Sindi, Cevat Teymuri

    2012-10-01

    In this article, fracture toughness behavior of tool steel was investigated using Acoustic Emission (AE) monitoring. Fracture toughness ( K IC) values of a specific tool steel was determined by applying various approaches based on conventional AE parameters, such as Acoustic Emission Cumulative Count (AECC), Acoustic Emission Energy Rate (AEER), and the combination of mechanical characteristics and AE information called sentry function. The critical fracture toughness values during crack propagation were achieved by means of relationship between the integral of the sentry function and cumulative fracture toughness (KICUM). Specimens were selected from AISI D2 cold-work tool steel and were heat treated at four different tempering conditions (300, 450, 525, and 575 °C). The results achieved through AE approaches were then compared with a methodology proposed by compact specimen testing according to ASTM standard E399. It was concluded that AE information was an efficient method to investigate fracture characteristics.

  19. Deformation pathways and breakup modes in acoustically levitated bicomponent droplets under external heating

    Science.gov (United States)

    Pathak, Binita; Basu, Saptarshi

    2016-03-01

    Controlled breakup of droplets using heat or acoustics is pivotal in applications such as pharmaceutics, nanoparticle production, and combustion. In the current work we have identified distinct thermal acoustics-induced deformation regimes (ligaments and bubbles) and breakup dynamics in externally heated acoustically levitated bicomponent (benzene-dodecane) droplets with a wide variation in volatility of the two components (benzene is significantly more volatile than dodecane). We showcase the physical mechanism and universal behavior of droplet surface caving in leading to the inception and growth of ligaments. The caving of the top surface is governed by a balance between the acoustic pressure field and the restrictive surface tension of the droplet. The universal collapse of caving profiles for different benzene concentration (growth. Subsequent ligament breakup is primarily Rayleigh-Plateau type. The breakup mode shifts to diffusional entrapment-induced boiling with an increase in concentration of the volatile component (benzene >70 % by volume). The findings are portable to any similar bicomponent systems with differential volatility.

  20. A theoretical estimation of the pre-breakdown-heating time in the underwater discharge acoustic source

    Institute of Scientific and Technical Information of China (English)

    Wang Yi-Bo; Wang Shang-Wu; Zeng Xin-Wu

    2012-01-01

    One of the common characteristics of the electrothermal breakdown in an underwater discharge acoustic source(UDAS)is the existence of a pre-breakdown-heating phase.In our experiment,two phenomena were observed:(1)the breakdown time that takes on high randomicity and obeys a "double-peak" stochastic distribution;(2)the higher salt concentration that reduces the residual voltage and causes 100% non-breakdown.The mechanism of electrothermal breakdown is analysed.To specify the end of the pre-breakdown-heating phase,a "border boiling" assumption is proposed,in which the breakdown time is assumed to be the time needed to heat the border water around the initial arc to 773 K.Based on this ‘border boiling' assumption,the numerical simulation is performed to evaluate the effects of two heating mechanisms:the Joule heating from the ionic current,and the radiation heating from the initial arc.The simulation results verify the theoretical explanations to these two experiment phenomena:(1)the stochastic distribution of the radius of the initial arc results in the randomicity of the breakdown time;(2)the difference in efficiency between the radiation heating and the Joule heating determines that,in the case of higher salt concentration,more energy will be consumed in the pre-breakdown-heating phase.

  1. Acoustic properties of pistonphones at low frequencies in the presence of pressure leakage and heat conduction

    Science.gov (United States)

    Zhang, Fan; He, Wen; He, Longbiao; Rong, Zuochao

    2015-12-01

    The wide concern on absolute pressure calibration of acoustic transducers at low frequencies prompts the development of the pistonphone method. At low frequencies, the acoustic properties of pistonphones are governed by the pressure leakage and the heat conduction effects. However, the traditional theory for these two effects applies a linear superposition of two independent correction models, which differs somewhat from their coupled effect at low frequencies. In this paper, acoustic properties of pistonphones at low frequencies in full consideration of the pressure leakage and heat conduction effects have been quantitatively studied, and the explicit expression for the generated sound pressure has been derived. With more practical significance, a coupled correction expression for these two effects of pistonphones has been derived. In allusion to two typical pistonphones, the NPL pistonphone and our developed infrasonic pistonphone, comparisons were done for the coupled correction expression and the traditional one, whose results reveal that the traditional one produces maximum insufficient errors of about 0.1 dB above the lower limiting frequencies of two pistonphones, while at lower frequencies, excessive correction errors with an explicit limit of about 3 dB are produced by the traditional expression. The coupled correction expression should be adopted in the absolute pressure calibration of acoustic transducers at low frequencies. Furthermore, it is found that the heat conduction effect takes a limiting deviation of about 3 dB for the pressure amplitude and a small phase difference as frequency decreases, while the pressure leakage effect remarkably drives the pressure amplitude to attenuate and the phase difference tends to be 90° as the frequency decreases. The pressure leakage effect plays a more important role on the low frequency property of pistonphones.

  2. Standard practice for acoustic emission examination of cast iron yankee and steam heated paper dryers

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This practice provides guidelines for carrying out acoustic emission (AE) examinations of Yankee and Steam Heated Paper Dryers (SHPD) of the type to make tissue, paper, and paperboard products. 1.2 This practice requires pressurization to levels used during normal operation. The pressurization medium may be high temperature steam, air, or gas. The dryer is also subjected to significant stresses during the heating up and cooling down periods of operation. Acoustic Emission data maybe collected during these time periods but this testing is beyond the scope of this document. 1.3 The AE measurements are used to detect, as well as, localize emission sources. Other methods of nondestructive testing (NDT) may be used to further evaluate the significance of acoustic emission sources. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine th...

  3. Heat release and flame structure measurements of self-excited acoustically-driven premixed methane flames

    Energy Technology Data Exchange (ETDEWEB)

    Kopp-Vaughan, Kristin M.; Tuttle, Steven G.; Renfro, Michael W. [Department of Mechanical Engineering, University of Connecticut, 191 Auditorium Rd, U-3139, Storrs, CT 06269 (United States); King, Galen B. [School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907 (United States)

    2009-10-15

    An open-open organ pipe burner (Rijke tube) with a bluff-body ring was used to create a self-excited, acoustically-driven, premixed methane-air conical flame, with equivalence ratios ranging from 0.85 to 1.05. The feed tube velocities corresponded to Re = 1780-4450. Coupled oscillations in pressure, velocity, and heat release from the flame are naturally encouraged at resonant frequencies in the Rijke tube combustor. This coupling creates sustainable self-excited oscillations in flame front area and shape. The period of the oscillations occur at the resonant frequency of the combustion chamber when the flame is placed {proportional_to}1/4 of the distance from the bottom of the tube. In this investigation, the shape of these acoustically-driven flames is measured by employing both OH planar laser-induced fluorescence (PLIF) and chemiluminescence imaging and the images are correlated to simultaneously measured pressure in the combustor. Past research on acoustically perturbed flames has focused on qualitative flame area and heat release relationships under imposed velocity perturbations at imposed frequencies. This study reports quantitative empirical fits with respect to pressure or phase angle in a self-generated pressure oscillation. The OH-PLIF images were single temporal shots and the chemiluminescence images were phase averaged on chip, such that 15 exposures were used to create one image. Thus, both measurements were time resolved during the flame oscillation. Phase-resolved area and heat release variations throughout the pressure oscillation were computed. A relation between flame area and the phase angle before the pressure maximum was derived for all flames in order to quantitatively show that the Rayleigh criterion was satisfied in the combustor. Qualitative trends in oscillating flame area were found with respect to feed tube flow rates. A logarithmic relation was found between the RMS pressure and both the normalized average area and heat release rate

  4. A comparison between acoustic properties and heat effects in biogenic (magnetosomes) and abiotic magnetite nanoparticle suspensions

    Science.gov (United States)

    Józefczak, A.; Leszczyński, B.; Skumiel, A.; Hornowski, T.

    2016-06-01

    Magnetic nanoparticles show unique properties and find many applications because of the possibility to control their properties using magnetic field. Magnetic nanoparticles are usually synthesized chemically and modification of the particle surface is necessary. Another source of magnetic nanoparticles are various magnetotactic bacteria. These biogenic nanoparticles (magnetosomes) represent an attractive alternative to chemically synthesized iron oxide particles because of their unique characteristics and a high potential for biotechnological and biomedical applications. This work presents a comparison between acoustic properties of biogenic and abiotic magnetite nanoparticle suspensions. Experimental studies have shown the influence of a biological membrane on the ultrasound properties of magnetosomes suspension. Finally the heat effect in synthetic and biogenic magnetite nanoparticles is also discussed. The experimental study shows that magnetosomes present good heating efficiency.

  5. Acoustic resonance excitation of turbulent heat transfer and flow reattachment downstream of a fence

    Science.gov (United States)

    Selcan, Claudio; Cukurel, Beni; Shashank, Judah

    2016-10-01

    The current work investigates the aero-thermal impact of standing sound waves, excited in a straight channel geometry, on turbulent, separating and reattaching flow over a fence. Effects of distinct frequency resonant forcing (ReH = 10,050 and f = 122 Hz) are quantified by wall static pressure measurements and detailed convective heat transfer distributions via liquid crystal thermometry. Acoustic boundary conditions are numerically predicted and the computed longitudinal resonance mode shapes are experimentally verified by surface microphone measurements. Findings indicate the presence of a resonant sound field to exert strong influence on local heat transfer downstream of the fence, whereas the boundary layer upstream of the obstacle remains notable unaffected. Upstream shift of the maximum heat transfer location and an earlier pressure recovery indicate a reduction in time averaged flow reattachment length of up to 37 %. Although the streamwise peak Nusselt increased by only 5 %, the heat transfer level in the vicinity of the unexcited reattachment zone was locally enhanced up to 25 %. Despite prominent impact of resonant forcing on the fence wake flow, the total pressure drop penalty remained invariant. Observations demonstrate the significant aero-thermal implications of shear layer excitation by standing sound waves superimposed on the channel flow field.

  6. Rayleigh surface acoustic wave as an efficient heating system for biological reactions: investigation of microdroplet temperature uniformity.

    Science.gov (United States)

    Roux-Marchand, Thibaut; Beyssen, Denis; Sarry, Frederic; Elmazria, Omar

    2015-04-01

    When a microdroplet is put on the Rayleigh surface acoustic wave path, longitudinal waves are radiated into the liquid and induce several phenomena such as the wellknown surface acoustic wave streaming. At the same time, the temperature of the microdroplet increases as it has been shown. In this paper, we study the temperature uniformity of a microdroplet heated by Rayleigh surface acoustic wave for discrete microfluidic applications such as biological reactions. To precisely ascertain the temperature uniformity and not interfere with the biological reaction, we used an infrared camera. We then tested the temperature uniformity as a function of three parameters: the microdroplet volume, the Rayleigh surface acoustic wave frequency, and the continuous applied radio frequency power. Based on these results, we propose a new device structure to develop a future lab on a chip based on reaction temperatures.

  7. Acoustic Heating Versus Magnetic Phenomena: Which Clues Does Observation Give Us?

    Science.gov (United States)

    Schroeder, Klaus-Peter

    2013-07-01

    Chromospheric emission lines betray the amount of chromospheric heating - but by which processes is that? The existence of a basal flux from entirely inactive stars, most sharply defined in giant stars, has revived the arguments in favour of a universal, acoustic heating, which underlies all heating by magnetic phenomena. Still, a minimal coronal flux and recent, direct detections of magnetic photospheric mean-field of one to a few Gauss even in supposedly inactive, far-evolved cool giants seem not to match such a view, or does it? We briefly review crucial observational evidence available from single giant stars. What more can we learn from giants in eclipsing systems? These offer unique evidence such as spatial resolution and chromospheric density profiles. And the low gravity g of giants yields large, easier-to-observe scale-heights and typical dimensions l (l/R prop. 1/g). A bench-mark test for future chromospheric models? Zeta Aur systems have shown on many occasions localised density concentrations. Evidence for the action of local magnetic field? Food for a long discussion....

  8. Determination of bearing steel heat treatment with the use of the acoustic emission method

    Directory of Open Access Journals (Sweden)

    T. Z. Wozniak

    2010-10-01

    Full Text Available A study on the control of an extremely important stage of the martensitic-bainitic austempering and obtaining the M-B structure in the 100CrMnSi6-4 steel with the use of the acoustic emission (AE has been undertaken. In order to enrich retained austenite with carbon, steels are austempered at appropriately low temperatures. A martensitic transformation, resulting from diffusionless and displacive transformation is associated with significant AE signs. The strain energy produced during growth due to the shape change is reduced by plastic deformation. Predominant source of (AE is the movement of dislocations in order to relieve internal stresses.The heat treatment was performed in a modern, purpose-constructed device which simultaneously records acoustic emission effects. The signals were recorded with the use of an AE analyzer 20–800 kHz, and they were received by means of a broadband piezoelectric transducer with the use of a specialist card with a sampling frequency of 1200 kHz. The results regarding a correlation of austempering temperature and the maximum number of AE events and dilatometric results have been presented. This parameter can be used for precise Ms temperature estimation. Basing on microstructural investigations, it has been found that previously formed martensite with midrib morphology also accelerates the bainitic transformation.

  9. Determination of bearing steel heat treatment with the use of the acoustic emission method

    Directory of Open Access Journals (Sweden)

    T.Z. Woźniak

    2010-07-01

    Full Text Available A study on the control of an extremely important stage of the martensitic-bainitic austempering and obtaining the M-B structure in the 100CrMnSi6-4 steel with the use of the acoustic emission (AE has been undertaken. In order to enrich retained austenite with carbon,steels are austempered at appropriately low temperatures. A martensitic transformation, resulting from diffusionless and displacive transformation is associated with significant AE signs. The strain energy produced during growth due to the shape change is reduced by plastic deformation. Predominant source of (AE is the movement of dislocations in order to relieve internal stresses.The heat treatment was performed in a modern, purpose-constructed device which simultaneously records acoustic emission effects. The signals were recorded with the use of an AE analyzer 20–800 kHz, and they were received by means of a broadband piezoelectric transducer with the use of a specialist card with a sampling frequency of 1200 kHz. The results regarding a correlation of austempering temperature and the maximum number of AE events and dilatometric results have been presented. This parameter can be used for precise Ms temperatureestimation. Basing on microstructural investigations, it has been found that previously formed martensite with midrib morphology alsoaccelerates the bainitic transformation.

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

    Science.gov (United States)

    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

  11. Acoustic study of a linear low-density polyethylene film after modification of the crystalline structure by heating.

    Science.gov (United States)

    Tohmyoh, Hironori; Sakamoto, Yuhei

    2014-02-01

    We report on a hybrid microscopy technique that enables us to measure the acoustic properties of a thin polymer film together with an optical microscope image of the corresponding area. Linear low-density polyethylene films are heated to various temperatures and examined by the technique. Density of the film is increased by heating and its sound velocity is decreased compared with a film without heating. Also, spherulites can clearly be seen in the optical microscope image, supporting the thermal shrinkage of the film which can be detected by the present technique.

  12. Coupling between hydrodynamics, acoustics, and heat release in a self-excited unstable combustor

    Science.gov (United States)

    Harvazinski, Matthew E.; Huang, Cheng; Sankaran, Venkateswaran; Feldman, Thomas W.; Anderson, William E.; Merkle, Charles L.; Talley, Douglas G.

    2015-04-01

    The unsteady gas dynamic field in a closed combustor is determined by the nonlinear interactions between chamber acoustics, hydrodynamics, and turbulent combustion that can energize these modes. These interactions are studied in detail using hybrid RANS/large eddy simulations (RANS = Reynolds Averaged Navier-Stokes) of a non-premixed, high-pressure laboratory combustor that produces self-excited longitudinal instabilities. The main variable in the study is the relative acoustic length between the combustion chamber and the tube that injects oxidizer into the combustor. Assuming a half-wave (closed-closed) combustion chamber, the tube lengths approximately correspond to quarter-, 3/8-, and half-wave resonators that serve to vary the phasing between the acoustic modes in the tube and the combustion chamber. The simulation correctly predicts the relatively stable behavior measured with the shortest tube and the very unstable behavior measured with the intermediate tube. Unstable behavior is also predicted for the longest tube, a case for which bifurcated stability behavior was measured in the experiment. In the first (stable) configuration, fuel flows into the combustor uninterrupted, and heat release is spatially continuous with a flame that remains attached to the back step. In the second (unstable) configuration, a cyclic process is apparent comprising a disruption in the fuel flow, subsequent detachment of the flame from the back step, and accumulation of fuel in the recirculation zone that ignites upon arrival of a compression wave reflected from the downstream boundary of the combustion chamber. The third case (mixed stable/unstable) shares features with both of the other cases. The major difference between the two cases predicted to be unstable is that, in the intermediate length tube, a pressure wave reflection inside the tube pushes unburnt fuel behind the back step radially outward, leading to a post-coupled reignition mechanism, while in the case of the

  13. Effect of electron heating on femtosecond laser-induced coherent acoustic phonons in noble metals

    Science.gov (United States)

    Wang, Jincheng; Guo, Chunlei

    2007-05-01

    We employ a surface plasmon technique to resolve the dynamics of femtosecond-laser-induced coherent acoustic phonons in noble metals. Clear acoustic oscillations are observed in our experiments. We further study the dependence of the initial phase of the oscillations on pump fluence, and we find that the initial phase decreases linearly with pump fluence. Our model calculations show that hot electrons instantaneously excited by femtosecond pulses contribute to the generation of coherent acoustic phonons in metals.

  14. Heat flux measured acoustically at Grotto Vent, a hydrothermal vent cluster on the Endeavour Segment, Juan de Fuca Ridge

    Science.gov (United States)

    Xu, G.; Jackson, D. R.; Bemis, K. G.; Rona, P. A.

    2013-12-01

    Over the past several decades, quantifying the heat output has been a unanimous focus of studies at hydrothermal vent fields discovered around the global ocean. Despite their importance, direct measurements of hydrothermal heat flux are very limited due to the remoteness of most vent sites and the complexity of hydrothermal venting. Moreover, almost all the heat flux measurements made to date are snapshots and provide little information on the temporal variation that is expected from the dynamic nature of a hydrothermal system. The Cabled Observatory Vent Imaging Sonar (COVIS, https://sites.google.com/a/uw.edu/covis/) is currently connected to the Endeavour node of the NEPTUNE Canada observatory network (http://www.neptunecanada.ca) to monitor the hydrothermal plumes issuing from a vent cluster (Grotto) on the Endeavour Segment of the Juan de Fuca Ridge. COVIS is acquiring a long-term (20-months to date) time series of the vertical flow rate and volume flux of the hydrothermal plume above Grotto through the Doppler analysis of the acoustic backscatter data (Xu et al., 2013). We then estimate the plume heat flux from vertical flow rate and volume flux using our newly developed inverse method. In this presentation, we will briefly summarize the derivation of the inverse method and present the heat-flux time series obtained consequently with uncertainty quantification. In addition, we compare our heat-flux estimates with the one estimated from the plume in-situ temperatures measured using a Remotely Operative Vehicle (ROV) in 2012. Such comparison sheds light on the uncertainty of our heat flux estimation. Xu, G., Jackson, D., Bemis, K., and Rona, P., 2013, Observations of the volume flux of a seafloor hydrothermal plume using an acoustic imaging sonar, Geochemistry, Geophysics Geosystems, 2013 (in press).

  15. Effect of acoustic streaming on tissue heating due to high-intensity focused ultrasound

    CERN Document Server

    Solovchuk, Maxim A; Thiriet, Marc; Lin, Win-Li

    2011-01-01

    The influences of blood vessels and focused location on temperature distribution during high-intensity focused ultrasound (HIFU) ablation of liver tumors is studied. A three-dimensional acoustics-thermal-fluid coupling model is employed to compute the temperature field in the hepatic cancerous region. The model is based on the linear Westervelt and bioheat equations as well as the nonlinear Navier-Stokes equations for the liver parenchyma and blood vessels. The effect of acoustic streaming is also taken into account in the present HIFU simulation study. Different blood vessel diameters and focal point locations were investigated. We found from this three-dimensional numerical study that in large blood vessels both the convective cooling and acoustic streaming can change considerably the temperature field and the thermal lesion near blood vessels. If the blood vessel is located within the beam width, both acoustic streaming and blood flow cooling effects should be taken into account. The predicted temperature ...

  16. Practical modeling of acoustic losses in air due to heat conduction and viscosity

    DEFF Research Database (Denmark)

    Christensen, René; Juhl, Peter Møller; Cutanda Henríquez, Vicente

    2008-01-01

    Accurate acoustics models of small devices with cavities and narrow slits and ducts should include the socalled boundary layer attenuation caused by thermal conduction and viscosity. The purpose of this paper is to present and compare different methods for including these loss mechanisms in analy......Accurate acoustics models of small devices with cavities and narrow slits and ducts should include the socalled boundary layer attenuation caused by thermal conduction and viscosity. The purpose of this paper is to present and compare different methods for including these loss mechanisms...

  17. Effects of heat exchange and nonlinearity on acoustic streaming in a vibrating cylindrical cavity.

    Science.gov (United States)

    Gubaidullin, Amir A; Yakovenko, Anna V

    2015-06-01

    Acoustic streaming in a gas filled cylindrical cavity subjected to the vibration effect is investigated numerically. Both thermally insulated walls and constant temperature walls are considered. The range of vibration frequencies from low frequencies, at which the process can be described by an approximate analytical solution, to high frequencies giving rise to strong nonlinear effects is studied. Frequencies lower than the resonant one are chosen, and nonlinearity is achieved due to the large amplitude. The problem is solved in an axisymmetric statement. The dependence of acoustic streaming in narrow channels at vibration frequencies lower than the resonant one on the type of thermal boundary conditions is shown. The streaming vortices' directions of rotation in the case of constant temperature walls are found to be opposite to those in the case of thermally insulated walls. Different nonlinear effects, which increase with the frequency of vibration, are obtained. Nonlinear effects manifesting as the nonuniformity of average temperature, pressure, and density are in turn found to be influencing the streaming velocity and streaming structure.

  18. Heat transfer in an acoustic-resonance tube model and its visualization; Onkyo kyomeikan ni okeru netsuyuso gensho to sono kashika

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, M.; Kataoka, M. [Kansei Gakuin University, Osaka (Japan). Faculty of Engineering; Kawamoto, A. [Toshiba Corp., Tokyo (Japan); Takifuji, T. [Hitachi, Ltd., Tokyo (Japan)

    1994-12-25

    Acoustic-resonance freezing was devised recently by Wheatley et al that could be called wave freezing that may be applied to chillers used in from small home air conditioners and refrigerators to those for industrial use. With an objective of using these chillers in practical applications, the present study has experimented and discussed the temperature distribution in tubes, transient dynamic movements, and correlation with acoustic fields by using a fundamental resonance model from among the basic design data. The experimental device consists of a speaker for the acoustic vibrator, resonance tubes, and stacking members. Heat transfer in the acoustic resonance tube was experimented, and the temperature distribution in the stacking plates was observed visually by using a temperature sensing liquid quartz sheet. Heat transfer from joints to flank in the pressure amplitude was recognized, and a special temperature distribution was found to be formed by the resonance system. Qualitative elucidation is also possible on the frequency involved in the heat transportation by means of a short stack model and the correlation with kinds of the fluids. Modeling the system as a whole requires further studies. The tested gases include nitrogen, air, R-22 fluorocarbon gas, and helium. 15 refs., 10 figs.

  19. Dynamics, Heat Transport, Spectral Composition and Acoustic Signatures of Mesoscale Variability in the Ocean

    Science.gov (United States)

    2013-12-01

    the present thesis research would have been in vain were it not by the invaluable orientation of my advisor, Dr. Timour Radko. His pedagogical skills...streamfunction or any other property after equilibration. The following diagnostics are based on the equilibrated PV fluxes. The parameters βnd and r are...and is likely to apply to different models. The diagnostics are focused on RMS velocity and heat flux since they are computed from a second order

  20. Evaluation of microscopic deformation behaviors of metal matrix composite by means of SFC test and acoustic emission (Part I :Effect of heat treatment on IFSS)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joon Hyun; Kang, Moon Phil [Pusan National University, Pusan (Korea, Republic of)

    1998-11-15

    Metal matrix composites(MMCs) are rapidly becoming one of the strongest candidates for structural materials for high temperature application. It is well recognized that MMCs always experience at least one large cool-down from processing temperature before any significant applied service loading. Due to the large difference in thermal expansion coefficient between the fiber and matrix, large thermal residual stresses generally develop in composites. It was reported from many previous studies that the effects of thermal residual stress on mechanical properties and fracture behavior were much more complex and dramatic than conventional engineering materials. Therefore it is crucial to evaluate the effect of heat treatment which changes the characteristic of distribution of thermal residual stress in MMCs. Single fiber composite(SFC) test based on the balance in a micromechanical model is a quite convenient method to evaluate interfacial shear strength(IFSS) and the failure mode of composite. In this study the effect of heat treatment on IFSS and the microscopic failure mechanism of MMC is investigated by combining acoustic emission(AE) technique with fragmentation test. The characteristic of AE signal, IFSS and microscopic failure mechanism due to heat treatment condition is discussed.

  1. Evaluation of Microscopic Deformation Behaviors of Metal Matrix Composite due to Heat Treatment by means of SFC Test and Acoustic Emission

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Moon Phil; Lee, Joon Hyun [Pusan National University, Busan (Korea, Republic of)

    2000-10-15

    Metal matrix composite(MMCs) have been rapidly becoming one of the strongest candidates for structural materials for high temperature application. It is well recognized that MMCs always experience at least one large cool-down from processing temperature before my significant applied service loading. Due to the large difference in thermal expansion coefficient between the fiber and matrix, large thermal residual stresses generally develop in composites. It was reported from many previous studies that the effects of thermal residual stress on mechanical properties and fracture behavior were much more complex and dramatic than conventional engineering materials. Therefore it is crucial to evaluate the effect of heat treatment which changes the characteristic of distribution of thermal residual stress in MMCs. Single fiber composite(SFC) test based on the balance in a micromechanical model is a quite convenient method to evaluate interfacial shear strength(IFSS) and the failure mode of composite. In this study the effect of heat treatment on IFSS and the microscopic failure mechanism of MMC is investigated by combining acoustic emission(AE) technique with SFC test. The characteristic of AE signal, IFSS and microscopic failure mechanism due to heat treatment condition is discussed

  2. Architectural acoustics

    National Research Council Canada - National Science Library

    Long, Marshall

    2014-01-01

    .... Beginning with a brief history, it reviews the fundamentals of acoustics, human perception and reaction to sound, acoustic noise measurements, noise metrics, and environmental noise characterization...

  3. Passive broadband acoustic thermometry

    Science.gov (United States)

    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.

  4. Virtual Acoustics

    Science.gov (United States)

    Lokki, Tapio; Savioja, Lauri

    The term virtual acoustics is often applied when sound signal is processed to contain features of a simulated acoustical space and sound is spatially reproduced either with binaural or with multichannel techniques. Therefore, virtual acoustics consists of spatial sound reproduction and room acoustics modeling.

  5. Acoustic field modulation in regenerators

    Science.gov (United States)

    Hu, J. Y.; Wang, W.; Luo, E. C.; Chen, Y. Y.

    2016-12-01

    The regenerator is a key component that transfers energy between heat and work. The conversion efficiency is significantly influenced by the acoustic field in the regenerator. Much effort has been spent to quantitatively determine this influence, but few comprehensive experimental verifications have been performed because of difficulties in modulating and measuring the acoustic field. In this paper, a method requiring two compressors is introduced and theoretically investigated that achieves acoustic field modulation in the regenerator. One compressor outputs the acoustic power for the regenerator; the other acts as a phase shifter. A RC load dissipates the acoustic power out of both the regenerator and the latter compressor. The acoustic field can be modulated by adjusting the current in the two compressors and opening the RC load. The acoustic field is measured with pressure sensors instead of flow-field imaging equipment, thereby greatly simplifying the experiment.

  6. Acoustic cryocooler

    Science.gov (United States)

    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.

  7. Heating of carriers as controlled by the combined interactions with acoustic and piezoelectric phonons in degenerate III-V semiconductors at low lattice temperature

    Science.gov (United States)

    Bhattacharya, D. P.; Das, J.; Basu, A.; Das, B.

    2017-09-01

    In compound semiconductors which lack inversion symmetry, the combined interaction of the electrons with both acoustic and piezoelectric phonons is dominant at low lattice temperatures ( 20 K). The field dependence of the effective electron temperature under these conditions, has been calculated by solving the modified energy balance equation that takes due account of the degeneracy. The traditionally used heated Fermi-Dirac (F.D.) function for the non-equilibrium distribution function is approximated by some well tested model distribution. This makes it possible to carry out the integrations quite easily and, thus to obtain some more realistic results in a closed form, without taking recourse to any oversimplified approximations. The numerical results that follow for InSb, InAs and GaN, from the present analysis, are then compared with the available theoretical and experimental data. The degeneracy and the piezoelectric interaction, both are seen to bring about significant changes in the electron temperature characteristics. The scope for further refinement is discussed.

  8. Calculation of the Acoustic Spectrum of a Cylindrical Vortex in Viscous Heat-Conducting Gas Based on the Navier–Stokes Equations

    Directory of Open Access Journals (Sweden)

    Tatiana Petrova

    2016-08-01

    Full Text Available An extremely interesting problem in aero-hydrodynamics is the sound radiation of a single vortical structure. Currently, this type of problem is mainly considered for an incompressible medium. In this paper a method was developed to take into account the viscosity and thermal conductivity of gas. The acoustic radiation frequency of a cylindrical vortex on a flat wall in viscous heat-conducting gas (air has been investigated. The problem is solved on the basis of the Navier–Stokes equations using the small initial vorticity approach. The power expansion of unknown functions in a series with a small parameter (vorticity is used. It is shown that there are high-frequency oscillations modulated by a low-frequency signal. The value of the high frequency remains constant for a long period of time. Thus the high frequency can be considered a natural frequency of the vortex radiation. The value of the natural frequency depends only on the initial radius of the cylindrical vortex, and does not depend on the intensity of the initial vorticity. As expected from physical considerations, the natural frequency decreases exponentially as the initial radius of the cylinder increases. Furthermore, the natural frequency differs from that of the oscillations inside the initial cylinder and in the outer domain. The results of the paper may be of interest for aeroacoustics and tornado modeling.

  9. Communication Acoustics

    DEFF Research Database (Denmark)

    Blauert, Jens

    Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......: acoustics, cognitive science, speech science, and communication technology....

  10. Acoustic telemetry

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To determine movements of green turtles in the nearshore foraging areas, we deployed acoustic tags and determined their movements through active and passive acoustic...

  11. Acoustic cloaking and transformation acoustics

    Energy Technology Data Exchange (ETDEWEB)

    Chen Huanyang [School of Physical Science and Technology, Soochow University, Suzhou, Jiangsu 215006 (China); Chan, C T, E-mail: kenyon@ust.h, E-mail: phchan@ust.h [Department of Physics and the William Mong Institute of NanoScience and Technology, The Hong Kong University of Science and Technology, Clear Water Bay (Hong Kong)

    2010-03-24

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

  12. Acoustical Imaging

    CERN Document Server

    Litniewski, Jerzy; Kujawska, Tamara; 31st International Symposium on Acoustical Imaging

    2012-01-01

    The International Symposium on Acoustical Imaging is a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. This interdisciplinary Symposium has been taking place continuously since 1968. In the course of the years the proceedings volumes in the Acoustical Imaging Series have become a reference for cutting-edge research in the field. In 2011 the 31st International Symposium on Acoustical Imaging was held in Warsaw, Poland, April 10-13. Offering both a broad perspective on the state-of-the-art as well as  in-depth research contributions by the specialists in the field, this Volume 31 in the Series contains an excellent collection of papers in six major categories: Biological and Medical Imaging Physics and Mathematics of Acoustical Imaging Acoustic Microscopy Transducers and Arrays Nondestructive Evaluation and Industrial Applications Underwater Imaging

  13. Acoustic biosensors

    OpenAIRE

    Fogel, Ronen; Limson, Janice; 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 ...

  14. Acoustic textiles

    CERN Document Server

    Nayak, Rajkishore

    2016-01-01

    This book highlights the manufacturing and applications of acoustic textiles in various industries. It also includes examples from different industries in which acoustic textiles can be used to absorb noise and help reduce the impact of noise at the workplace. Given the importance of noise reduction in the working environment in several industries, the book offers a valuable guide for companies, educators and researchers involved with acoustic materials.

  15. Communication Acoustics

    DEFF Research Database (Denmark)

    Blauert, Jens

    the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... chapters represent review articles covering the most relevant areas of the field. They are written with the goal of providing students with comprehensive introductions. Further they offer a supply of numerous references to the relevant literature. Besides its usefulness as a textbook, this will make...

  16. Radiation acoustics

    CERN Document Server

    Lyamshev, Leonid M

    2004-01-01

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

  17. Heat Transfer in a Thermoacoustic Process

    Science.gov (United States)

    Beke, Tamas

    2012-01-01

    Thermoacoustic instability is defined as the excitation of acoustic modes in chambers with heat sources due to the coupling between acoustic perturbations and unsteady heat addition. The major objective of this paper is to achieve accurate theoretical results in a thermoacoustic heat transfer process. We carry out a detailed heat transfer analysis…

  18. Heat Transfer in a Thermoacoustic Process

    Science.gov (United States)

    Beke, Tamas

    2012-01-01

    Thermoacoustic instability is defined as the excitation of acoustic modes in chambers with heat sources due to the coupling between acoustic perturbations and unsteady heat addition. The major objective of this paper is to achieve accurate theoretical results in a thermoacoustic heat transfer process. We carry out a detailed heat transfer analysis…

  19. Performance of several viscothermal acoustic finite elements

    NARCIS (Netherlands)

    Kampinga, W.R.; Wijnant, Y.H.; Boer, de A.

    2010-01-01

    Viscothermal acoustics can be described by the linearized Navier Stokes equations. Besides inertia and compressibility, these equations take the heat conductivity and the viscosity of the medium (air) into account. These 'viscothermal' effects are significant in, for example, miniature acoustic tran

  20. Acoustic power measurements of oscillating flames

    NARCIS (Netherlands)

    Valk, M.

    1981-01-01

    The acoustic power of an oscillating flame is measured. A turbulent premixed propane/air flame is situated near a pressure antinode of a standing wave in a laboratory combustion chamber. This standing wave is generated by a piston. The fluctuating heat release of the flame will supply acoustic power

  1. Acoustic power measurements of oscillating flames

    NARCIS (Netherlands)

    Valk, M.

    1981-01-01

    The acoustic power of an oscillating flame is measured. A turbulent premixed propane/air flame is situated near a pressure antinode of a standing wave in a laboratory combustion chamber. This standing wave is generated by a piston. The fluctuating heat release of the flame will supply acoustic power

  2. Acoustics Research

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fisheries acoustics data are collected from more than 200 sea-days each year aboard the FRV DELAWARE II and FRV ALBATROSS IV (decommissioned) and the FSV Henry B....

  3. Battlefield acoustics

    CERN Document Server

    Damarla, Thyagaraju

    2015-01-01

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

  4. Acoustical Imaging

    CERN Document Server

    Akiyama, Iwaki

    2009-01-01

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

  5. Room Acoustics

    Science.gov (United States)

    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.

  6. A Martian acoustic anemometer.

    Science.gov (United States)

    Banfield, Don; Schindel, David W; Tarr, Steve; Dissly, Richard W

    2016-08-01

    An acoustic anemometer for use on Mars has been developed. To understand the processes that control the interaction between surface and atmosphere on Mars, not only the mean winds, but also the turbulent boundary layer, the fluxes of momentum, heat and molecular constituents between surface and atmosphere must be measured. Terrestrially this is done with acoustic anemometers, but the low density atmosphere on Mars makes it challenging to adapt such an instrument for use on Mars. This has been achieved using capacitive transducers and pulse compression, and was successfully demonstrated on a stratospheric balloon (simulating the Martian environment) and in a dedicated Mars Wind Tunnel facility. This instrument achieves a measurement accuracy of ∼5 cm/s with an update rate of >20 Hz under Martian conditions.

  7. Acoustic biosensors

    Science.gov (United States)

    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

  8. Droplets Acoustics

    CERN Document Server

    Dahan, Raphael; Carmon, Tal

    2015-01-01

    Contrary to their capillary resonances (Rayleigh, 1879) and their optical resonances (Ashkin, 1977), droplets acoustical resonances were rarely considered. Here we experimentally excite, for the first time, the acoustical resonances of a droplet that relies on sound instead of capillary waves. Droplets vibrations at 37 MHz rates and 100 quality factor are optically excited and interrogated at an optical threshold of 68 microWatt. Our vibrations span a spectral band that is 1000 times higher when compared with drops previously-studied capillary vibration.

  9. Acoustic transducer for acoustic microscopy

    Science.gov (United States)

    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.

  10. Acoustical-Levitation Chamber for Metallurgy

    Science.gov (United States)

    Barmatz, M. B.; Trinh, E.; Wang, T. G.; Elleman, D. D.; Jacobi, N.

    1983-01-01

    Sample moved to different positions for heating and quenching. Acoustical levitation chamber selectively excited in fundamental and second-harmonic longitudinal modes to hold sample at one of three stable postions: A, B, or C. Levitated object quickly moved from one of these positions to another by changing modes. Object rapidly quenched at A or C after heating in furnace region at B.

  11. Acoustic dose and acoustic dose-rate.

    Science.gov (United States)

    Duck, Francis

    2009-10-01

    Acoustic dose is defined as the energy deposited by absorption of an acoustic wave per unit mass of the medium supporting the wave. Expressions for acoustic dose and acoustic dose-rate are given for plane-wave conditions, including temporal and frequency dependencies of energy deposition. The relationship between the acoustic dose-rate and the resulting temperature increase is explored, as is the relationship between acoustic dose-rate and radiation force. Energy transfer from the wave to the medium by means of acoustic cavitation is considered, and an approach is proposed in principle that could allow cavitation to be included within the proposed definitions of acoustic dose and acoustic dose-rate.

  12. Use of acoustic vortices in acoustic levitation

    DEFF Research Database (Denmark)

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

    2009-01-01

    Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without...

  13. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... Back Learn about acoustic neuroma AN Facts What is acoustic neuroma? Diagnosing Symptoms Side Effects Keywords Questions ... kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms Side effects Question To ...

  14. Topology optimization for enhancing the acoustical and thermal characteristics of acoustic devices simultaneously

    Science.gov (United States)

    Oh, Kee Seung; Lee, Jin Woo

    2017-08-01

    In this study, an optimal design method was developed using topology optimization for an acoustic device in the presence of temperature gradient. Although acoustic properties were strongly affected by temperature distribution, many topology optimization problems for optimal acoustic devices were formulated under the assumption that temperature was uniformly distributed in the design domain or that heat transfer through boundaries was negligible. An acoustically optimized topology could negatively influence the heat transfer characteristics of a mechanical device. To figure out this issue, thermo-acoustical topology optimization problems were formulated for an optimal design of the acoustic device. A general form of a finite element equation was developed for acoustical and thermal analyses, and interpolation functions were carefully selected to obtain a black-and-white topology in the final step. Optimal design examples were solved for various acoustical and thermal design requirements, and the physical characteristics of an optimal muffler obtained using the proposed approach in the present study were compared with those of a well-known existing design.

  15. The role of acoustic nonlinearity in tissue heating behind a rib cage using a high-intensity focused ultrasound phased array.

    Science.gov (United States)

    Yuldashev, Petr V; Shmeleva, Svetlana M; Ilyin, Sergey A; Sapozhnikov, Oleg A; Gavrilov, Leonid R; Khokhlova, Vera A

    2013-04-21

    The goal of this study was to investigate theoretically the effects of nonlinear propagation in a high-intensity focused ultrasound (HIFU) field produced by a therapeutic phased array and the resultant heating of tissue behind a rib cage. Three configurations of focusing were simulated: in water, in water with ribs in the beam path and in water with ribs backed by a layer of soft tissue. The Westervelt equation was used to model the nonlinear HIFU field, and a 1 MHz phased array consisting of 254 circular elements was used as a boundary condition to the model. The temperature rise in tissue was modelled using the bioheat equation, and thermally necrosed volumes were calculated using the thermal dose formulation. The shapes of lesions predicted by the modelling were compared with those previously obtained in in vitro experiments at low-power sonications. Intensity levels at the face of the array elements that corresponded to the formation of high-amplitude shock fronts in the focal region were determined as 10 W cm(-2) in the free field in water and 40 W cm(-2) in the presence of ribs. It was shown that exposures with shocks provided a substantial increase in tissue heating, and its better spatial localization in the main focal region only. The relative effects of overheating ribs and splitting of the focus due to the periodic structure of the ribs were therefore reduced. These results suggest that utilizing nonlinear propagation and shock formation effects can be beneficial for inducing confined HIFU lesions when irradiating through obstructions such as ribs. Design of compact therapeutic arrays to provide maximum power outputs with lower intensity levels at the elements is necessary to achieve shock wave regimes for clinically relevant sonication depths in tissue.

  16. Use of acoustic vortices in acoustic levitation

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  17. Acoustic transducer

    Science.gov (United States)

    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 telemetry.

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. The Effect of Resistance on Rocket Injector Acoustics

    Science.gov (United States)

    Morgan, C. J.

    2015-01-01

    Combustion instability, where unsteady heat release couples with acoustic modes, has long been an area of concern in liquid rocket engines. Accurate modeling of the acoustic normal modes of the combustion chamber is important to understanding and preventing combustion instability. The injector resistance can have a significant influence on the chamber normal mode shape, and hence on the system stability.

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

    Science.gov (United States)

    Vargas, Magda B.; Counter, Douglas

    2011-01-01

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

  1. Pattern-formation under acoustic driving forces

    Science.gov (United States)

    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.

  2. Springer Handbook of Acoustics

    CERN Document Server

    Rossing, Thomas D

    2007-01-01

    Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and others. The Springer Handbook of Acoustics is an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents spanning: animal acoustics including infrasound and ultrasound, environmental noise control, music and human speech and singing, physiological and psychological acoustics, architectural acoustics, physical and engineering acoustics, signal processing, medical acoustics, and ocean acoustics. This handbook reviews the most important areas of acoustics, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest rese...

  3. Responsive acoustic surfaces

    DEFF Research Database (Denmark)

    Peters, Brady; Tamke, Martin; Nielsen, Stig Anton

    2011-01-01

    Acoustic performance is defined by the parameter of reverberation time; however, this does not capture the acoustic experience in some types of open plan spaces. As many working and learning activities now take place in open plan spaces, it is important to be able to understand and design...... for the acoustic conditions of these spaces. This paper describes an experimental research project that studied the design processes necessary to design for sound. A responsive acoustic surface was designed, fabricated and tested. This acoustic surface was designed to create specific sonic effects. The design...... was simulated using custom integrated acoustic software and also using Odeon acoustic analysis software. The research demonstrates a method for designing space- and sound-defining surfaces, defines the concept of acoustic subspace, and suggests some new parameters for defining acoustic subspaces....

  4. Acoustic Spatiality

    Directory of Open Access Journals (Sweden)

    Brandon LaBelle

    2012-06-01

    Full Text Available Experiences of listening can be appreciated as intensely relational, bringing us into contact with surrounding events, bodies and things. Given that sound propagates and expands outwardly, as a set of oscillations from a particular source, listening carries with it a sensual intensity, whereby auditory phenomena deliver intrusive and disruptive as well as soothing and assuring experiences. The physicality characteristic of sound suggests a deeply impressionistic, locational "knowledge structure" – that is, the ways in which listening affords processes of exchange, of being in the world, and from which we extend ourselves. Sound, as physical energy reflecting and absorbing into the materiality around us, and even one's self, provides a rich platform for understanding place and emplacement. Sound is always already a trace of location.Such features of auditory experience give suggestion for what I may call an acoustical paradigm – how sound sets in motion not only the material world but also the flows of the imagination, lending to forces of signification and social structure, and figuring us in relation to each other. The relationality of sound brings us into a steady web of interferences, each of which announces the promise or problematic of being somewhere.

  5. Acoustic Neurinomas

    Directory of Open Access Journals (Sweden)

    Mohammad Faraji Rad

    2011-01-01

    Full Text Available Acoustic neuromas (AN are schwann cell-derived tumors that commonly arise from the vestibular portion of the eighth cranial nerve also known as vestibular schwannoma(VS causes unilateral hearing loss, tinnitus, vertigo and unsteadiness. In many cases, the tumor size may remain unchanged for many years following diagnosis, which is typically made by MRI. In the majority of cases the tumor is small, leaving the clinician and patient with the options of either serial scanning or active treatment by gamma knife radiosurgery (GKR or microneurosurgery. Despite the vast number of published treatment reports, comparative studies are few. The predominant clinical endpoints of AN treatment include tumor control, facial nerve function and hearing preservation. Less focus has been put on symptom relief and health-related quality of life (QOL. It is uncertain if treating a small tumor leaves the patient with a better chance of obtaining relief from future hearing loss, vertigo or tinnitus than by observing it without treatment.   In this paper we review the literature for the natural course, the treatment alternatives and the results of AN. Finally, we present our experience with a management strategy applied for more than 30 years.

  6. Acoustic Neurinomas

    Directory of Open Access Journals (Sweden)

    Mohammad Faraji Rad

    2011-01-01

    Full Text Available Acoustic neuromas (AN are schwann cell-derived tumors that commonly arise from the vestibular portion of the eighth cranial nerve also known as vestibular schwannoma(VS causes unilateral hearing loss, tinnitus, vertigo and unsteadiness. In many cases, the tumor size may remain unchanged for many years following diagnosis, which is typically made by MRI. In the majority of cases the tumor is small, leaving the clinician and patient with the options of either serial scanning or active treatment by gamma knife radiosurgery (GKR or microneurosurgery. Despite the vast number of published treatment reports, comparative studies are few. The predominant clinical endpoints of AN treatment include tumor control, facial nerve function and hearing preservation. Less focus has been put on symptom relief and health-related quality of life (QOL. It is uncertain if treating a small tumor leaves the patient with a better chance of obtaining relief from future hearing loss, vertigo or tinnitus than by observing it without treatment.   In this paper we review the literature for the natural course, the treatment alternatives and the results of AN. Finally, we present our experience with a management strategy applied for more than 30 years.

  7. Applications of adaptive focused acoustics to compound management.

    Science.gov (United States)

    Nixon, Elizabeth; Holland-Crimmin, Sue; Lupotsky, Brian; Chan, James; Curtis, Jon; Dobbs, Karen; Blaxill, Zoe

    2009-06-01

    Since the introduction of lithotripsy kidney stone therapy, Focused Acoustics and its properties have been thoroughly utilized in medicine and exploration. More recently, Compound Management is exploring its applications and benefits to sample integrity. There are 2 forms of Focused Acoustics: Acoustic Droplet Ejection and Adaptive Focused Acoustics, which work by emitting high-powered acoustic waves through water toward a focused point. This focused power results in noncontact plate-to-plate sample transfer or sample dissolution, respectively. For the purposes of this article, only Adaptive Focused Acoustics will be addressed. Adaptive Focused Acoustics uses high-powered acoustic waves to mix, homogenize, dissolve, and thaw samples. It facilitates transferable samples through noncontact, closed-container, isothermal mixing. Experimental results show significantly reduced mixing times, limited degradation, and ideal use for heat-sensitive compounds. Upon implementation, acoustic dissolution has reduced the number of samples requiring longer mixing times as well as reducing the number impacted by incomplete compound dissolution. It has also helped in increasing the overall sample concentration from 6 to 8 mM to 8 to 10 mM by ensuring complete compound solubilization. The application of Adaptive Focused Acoustics, however, cannot be applied to all Compound Management processes, such as sample thawing and low-volume sample reconstitution. This article will go on to describe the areas where Adaptive Focused Acoustics adds value as well as areas in which it has shown no clear benefit.

  8. Acoustic source for generating an acoustic beam

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  11. Atlantic Herring Acoustic Surveys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Advanced Sampling Technologies Research Group conducts annual fisheries acoustic surveys using state-of-the-art acoustic, midwater trawling, and underwater...

  12. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... acoustic neuroma resource Click to learn more... LOGIN EVENTS DONATE Home Learn Back Learn about acoustic neuroma ... support group for me? Find a Group Upcoming Events Video Library Photo Gallery One-on-One Support ...

  13. Investigation of the nature of thermal stimulation of acoustic emission

    Energy Technology Data Exchange (ETDEWEB)

    Muravin, G.B.; Ship, V.V.; Lezvinskaya, L.M.

    1988-12-01

    The nature of thermal stimulation of acoustic emission was investigated. Data are given on the distribution of the density of the energy of deformation at a crack tip and the parameters of acoustic emission with different combinations of mechanical and thermal action. It was established that thermal stimulation of acoustic emission is related to advance and growth of a crack under the action of thermoelastic shear stresses. An increases in heating power causes an increase in the energy of deformation, shear stresses at the crack edges, and acoustic emission energy. The position of the minimum in the density of the energy of deformation and of the maximum in acoustic emission energy coincides with the direction of crack advance, which with the use of the method of thermally stimulated acoustic emission makes it possible to not only reveal crack-like defects but also to determine potentially dangerous directions of their development.

  14. Acoustic Signals and Systems

    DEFF Research Database (Denmark)

    2008-01-01

    The Handbook of Signal Processing in Acoustics will compile the techniques and applications of signal processing as they are used in the many varied areas of Acoustics. The Handbook will emphasize the interdisciplinary nature of signal processing in acoustics. Each Section of the Handbook will pr...

  15. Tutorial on architectural acoustics

    Science.gov (United States)

    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).

  16. A one-dimensional heat transfer model for parallel-plate thermoacoustic heat exchangers

    NARCIS (Netherlands)

    de Jong, Anne; Wijnant, Ysbrand H.; de Boer, Andries

    2014-01-01

    A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic

  17. Indoor acoustic gain design

    Science.gov (United States)

    Concha-Abarca, Justo Andres

    2002-11-01

    The design of sound reinforcement systems includes many variables and usually some of these variables are discussed. There are criteria to optimize the performance of the sound reinforcement systems under indoor conditions. The equivalent acoustic distance, the necessary acoustic gain, and the potential acoustic gain are parameters which must be adjusted with respect to the loudspeaker array, electric power and directionality of loudspeakers, the room acoustics conditions, the distance and distribution of the audience, and the type of the original sources. The design and installation of front of the house and monitoring systems have individual criteria. This article is about this criteria and it proposes general considerations for the indoor acoustic gain design.

  18. Parametric Room Acoustic Workflows

    DEFF Research Database (Denmark)

    Parigi, Dario; Svidt, Kjeld; Molin, Erik

    2017-01-01

    The paper investigates and assesses different room acoustics software and the opportunities they offer to engage in parametric acoustics workflow and to influence architectural designs. The first step consists in the testing and benchmarking of different tools on the basis of accuracy, speed...... and interoperability with Grasshopper 3d. The focus will be placed to the benchmarking of three different acoustic analysis tools based on raytracing. To compare the accuracy and speed of the acoustic evaluation across different tools, a homogeneous set of acoustic parameters is chosen. The room acoustics parameters...... included in the set are reverberation time (EDT, RT30), clarity (C50), loudness (G), and definition (D50). Scenarios are discussed for determining at different design stages the most suitable acoustic tool. Those scenarios are characterized, by the use of less accurate but fast evaluation tools to be used...

  19. Cooling Acoustic Transducer with Heat Pipes

    Science.gov (United States)

    2009-07-29

    8217K\\,K\\’K\\’K\\’KS’K\\’K\\’KS’K\\’K\\’K\\’K\\l / / N\\N\\K\\K\\N\\N\\N\\N\\T\\\\N\\K\\T\\\\T\\\\K ’/777/y / L\\S.\\M.\\N,\\M\\M.\\M.SM.\\M.\\H\\H\\N.\\S,\\^^ / k\\HAHAV\\ HAHA ^H^VkVkV>lVlV’’ FIG. 5 FIG. 6

  20. Indirect detonation initiation using acoustic timescale thermal power deposition

    CERN Document Server

    Regele, Jonathan D; Vezolainen, Alexei; Vasilyev, Oleg V

    2012-01-01

    A fluid dynamics video is presented that demonstrates an indirect detonation initiation process. In this process, a transient power deposition adds heat to a spatially resolved volume of fluid in an amount of time that is similar to the acoustic timescale of the fluid volume. A highly resolved two-dimensional simulation shows the events that unfold after the heat is added.

  1. Vibro-acoustics

    CERN Document Server

    Nilsson, Anders

    2015-01-01

    This three-volume book gives a thorough and comprehensive presentation of vibration and acoustic theories. Different from traditional textbooks which typically deal with some aspects of either acoustic or vibration problems, it is unique of this book to combine those two correlated subjects together. Moreover, it provides fundamental analysis and mathematical descriptions for several crucial phenomena of Vibro-Acoustics which are quite useful in noise reduction, including how structures are excited, energy flows from an excitation point to a sound radiating surface, and finally how a structure radiates noise to a surrounding fluid. Many measurement results included in the text make the reading interesting and informative. Problems/questions are listed at the end of each chapter and the solutions are provided. This will help the readers to understand the topics of Vibro-Acoustics more deeply. The book should be of interest to anyone interested in sound and vibration, vehicle acoustics, ship acoustics and inter...

  2. Springer handbook of acoustics

    CERN Document Server

    2014-01-01

    Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and electronics. The Springer Handbook of Acoustics is also in his 2nd edition an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents. This new edition of the Handbook features over 11 revised and expanded chapters, new illustrations, and 2 new chapters covering microphone arrays  and acoustic emission.  Updated chapters contain the latest research and applications in, e.g. sound propagation in the atmosphere, nonlinear acoustics in fluids, building and concert hall acoustics, signal processing, psychoacoustics, computer music, animal bioacousics, sound intensity, modal acoustics as well as new chapters on microphone arrays an...

  3. Deep Water Ocean Acoustics

    Science.gov (United States)

    2016-04-30

    OASIS, INC. 1 Report No. QSR-14C0172-Ocean Acoustics-043016 Quarterly Progress Report Technical and Financial Deep Water Ocean Acoustics...understanding of the impact of the ocean and seafloor environmental variability on deep- water (long-range) ocean acoustic propagation and to...improve our understanding. During the past few years, the physics effects studied have been three-dimensional propagation on global scales, deep water

  4. Deep Water Ocean Acoustics

    Science.gov (United States)

    2016-10-07

    Res., 114, C07021. Evers, L. G. & Snellen , M., 2015. Passive probing of the sound fixing and ranging channel with hydro-acoustic observations from...ridge earthquakes, J. Acoust. Soc. Am., 137, 2124–2136. Evers, L. G., Green, D. N., Young, N. W., & Snellen , M., 2013. Remote hydroacoustic sensing...Heaney, K. D., Assink, J. D., Smets, P. S. M., & Snellen , M., 2014. Evanescent wave coupling in a geophysical system: Airborne acoustic signals from

  5. Nearfield Acoustical Holography

    Science.gov (United States)

    Hayek, Sabih I.

    Nearfield acoustical holography (NAH) is a method by which a set of acoustic pressure measurements at points located on a specific surface (called a hologram) can be used to image sources on vibrating surfaces on the acoustic field in three-dimensional space. NAH data are processed to take advantage of the evanescent wavefield to image sources that are separated less that one-eighth of a wavelength.

  6. Handbook of Engineering Acoustics

    CERN Document Server

    Möser, Michael

    2013-01-01

    This book examines the physical background of engineering acoustics, focusing on empirically obtained engineering experience as well as on measurement techniques and engineering methods for prognostics. Its goal is not only to describe the state of art of engineering acoustics but also to give practical help to engineers in order to solve acoustic problems. It deals with the origin, the transmission and the methods of the abating different kinds of air-borne and structure-borne sounds caused by various mechanisms – from traffic to machinery and flow-induced sound. In addition the modern aspects of room and building acoustics, as well as psychoacoustics and active noise control, are covered.

  7. Shallow Water Acoustic Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Supports experimental research where high-frequency acoustic scattering and surface vibration measurements of fluid-loaded and non-fluid-loaded structures...

  8. Acoustic Technology Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — This laboratory contains an electro-magnetic worldwide data collection and field measurement capability in the area of acoustic technology. Outfitted by NASA Langley...

  9. Localized Acoustic Surface Modes

    KAUST Repository

    Farhat, Mohamed

    2015-08-04

    We introduce the concept of localized acoustic surface modes (ASMs). 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.

  10. Laboratory for Structural Acoustics

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Supports experimental research where acoustic radiation, scattering, and surface vibration measurements of fluid-loaded and non-fluid-loaded structures are...

  11. Acoustic Signals and Systems

    DEFF Research Database (Denmark)

    2008-01-01

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

  12. Acoustic agglomeration of power plant fly ash. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Reethof, G.; McDaniel, O.H.

    1982-01-01

    The work has shown that acoustic agglomeration at practical acoustic intensities and frequencies is technically and most likely economically viable. The following studies were performed with the listed results: The physics of acoustic agglomeration is complex particularly at the needed high acoustic intensities in the range of 150 to 160 dB and frequencies in the 2500 Hz range. The analytical model which we developed, although not including nonlinear acoustic efforts, agreed with the trends observed. We concentrated our efforts on clarifying the impact of high acoustic intensities on the generation of turbulence. Results from a special set of tests show that although some acoustically generated turbulence of sorts exists in the 150 to 170 dB range with acoustic streaming present, such turbulence will not be a significant factor in acoustic agglomeration compared to the dominant effect of the acoustic velocities at the fundamental frequency and its harmonics. Studies of the robustness of the agglomerated particles using the Anderson Mark III impactor as the source of the shear stresses on the particles show that the agglomerates should be able to withstand the rigors of flow through commercial cyclones without significant break-up. We designed and developed a 700/sup 0/F tubular agglomerator of 8'' internal diameter. The electrically heated system functioned well and provided very encouraging agglomeration results at acoustic levels in the 150 to 160 dB and 2000 to 3000 Hz ranges. We confirmed earlier results that an optimum frequency exists at about 2500 Hz and that larger dust loadings will give better results. Studies of the absorption of acoustic energy by various common gases as a function of temperature and humidity showed the need to pursue such an investigation for flue gas constituents in order to provide necessary data for the design of agglomerators. 65 references, 56 figures, 4 tables.

  13. Acoustic fluidization for earthquakes?

    OpenAIRE

    Sornette, D.; Sornette, A.

    2000-01-01

    Melosh [1996] has suggested that acoustic fluidization could provide an alternative to theories that are invoked as explanations for why some crustal faults appear to be weak. We show that there is a subtle but profound inconsistency in the theory that unfortunately invalidates the results. We propose possible remedies but must acknowledge that the relevance of acoustic fluidization remains an open question.

  14. Acoustic diffusers III

    Science.gov (United States)

    Bidondo, Alejandro

    2002-11-01

    This acoustic diffusion research presents a pragmatic view, based more on effects than causes and 15 very useful in the project advance control process, where the sound field's diffusion coefficient, sound field diffusivity (SFD), for its evaluation. Further research suggestions are presented to obtain an octave frequency resolution of the SFD for precise design or acoustical corrections.

  15. Parametric Room Acoustic Workflows

    DEFF Research Database (Denmark)

    Parigi, Dario; Svidt, Kjeld; Molin, Erik

    2017-01-01

    The paper investigates and assesses different room acoustics software and the opportunities they offer to engage in parametric acoustics workflow and to influence architectural designs. The first step consists in the testing and benchmarking of different tools on the basis of accuracy, speed and ...

  16. Acoustic Aspects of Photoacoustic Signal Generation and Detection in Gases

    Science.gov (United States)

    Miklós, A.

    2015-09-01

    In this paper photoacoustic signal generation and detection in gases is investigated and discussed from the standpoint of acoustics. Four topics are considered: the effect of the absorption-desorption process of modulated and pulsed light on the heat power density released in the gas; the generation of the primary sound by the released heat in an unbounded medium; the excitation of an acoustic resonator by the primary sound; and finally, the generation of the measurable PA signal by a microphone. When light is absorbed by a molecule and the excess energy is relaxed by collisions with the surrounding molecules, the average kinetic energy, thus also the temperature of an ensemble of molecules (called "particle" in acoustics) will increase. In other words heat energy is added to the energy of the particle. The rate of the energy transfer is characterized by the heat power density. A simple two-level model of absorption-desorption is applied for describing the heat power generation process for modulated and pulsed illumination. Sound generation by a laser beam in an unbounded medium is discussed by means of the Green's function technique. It is shown that the duration of the generated sound pulse depends mostly on beam geometry. A photoacoustic signal is mostly detected in a photoacoustic cell composed of acoustic resonators, buffers, filters, etc. It is not easy to interpret the measured PA signal in such a complicated acoustic system. The acoustic response of a PA detector to different kinds of excitations (modulated cw, pulsed, periodic pulse train) is discussed. It is shown that acoustic resonators respond very differently to modulated cw excitation and to excitation by a pulse train. The microphone for detecting the PA signal is also a part of the acoustic system; its properties have to be taken into account by the design of a PA detector. The moving membrane of the microphone absorbs acoustic energy; thus, it may influence the resonance frequency and

  17. Synchronization of an Array of Miniature Acoustic Engines

    Science.gov (United States)

    Kwon, Young Sang; Symko, Orest G.

    2004-03-01

    In the development of miniature arrays of acoustic engines for energy conversion, phase-locking of the array ensemble was investigated. As the individual acoustic devices are independent resonant elements, maximum output can be achieved by a coherent summation of the elements of the array. They have small variations in resonant frequency and they have different phases as they are non-linear self-sustained oscillators and their phases depend on the initial conditions. The acoustic engines are based on thermoacoustics, where heat is converted to sound in a resonator by applying a temperature gradient across a stack of high surface area elements. In the experiments described here, the devices oscillate in the frequency range of 3 kHz and they are assembled into arrays of 5 elements and 9 elements. When the array is activated with heat, the acoustic power output is not coherent; it contains all sorts of beats and frequency mixtures produced by each independent oscillator. However, coherence is achieved by the introduction of a relatively weak signal from a separate resonator which phase-locks all the self-sustained acoustic oscillators and causes coherent summation of oscillations. Such approach provides a high intensity acoustic signal which can be used in energy conversion of heat to electricity.

  18. Computational Ocean Acoustics

    CERN Document Server

    Jensen, Finn B; Porter, Michael B; Schmidt, Henrik

    2011-01-01

    Since the mid-1970s, the computer has played an increasingly pivotal role in the field of ocean acoustics. Faster and less expensive than actual ocean experiments, and capable of accommodating the full complexity of the acoustic problem, numerical models are now standard research tools in ocean laboratories. The progress made in computational ocean acoustics over the last thirty years is summed up in this authoritative and innovatively illustrated new text. Written by some of the field's pioneers, all Fellows of the Acoustical Society of America, Computational Ocean Acoustics presents the latest numerical techniques for solving the wave equation in heterogeneous fluid–solid media. The authors discuss various computational schemes in detail, emphasizing the importance of theoretical foundations that lead directly to numerical implementations for real ocean environments. To further clarify the presentation, the fundamental propagation features of the techniques are illustrated in color. Computational Ocean A...

  19. Acoustic ground impedance meter

    Science.gov (United States)

    Zuckerwar, A. J. (Inventor)

    1984-01-01

    A method and apparatus are presented for measuring the acoustic impedance of a surface in which the surface is used to enclose one end of the chamber of a Helmholz resonator. Acoustic waves are generated in the neck of the resonator by a piston driven by a variable speed motor through a cam assembly. The acoustic waves are measured in the chamber and the frequency of the generated acoustic waves is measured by an optical device. These measurements are used to compute the compliance and conductance of the chamber and surface combined. The same procedure is followed with a calibration plate having infinite acoustic impedance enclosing the chamber of the resonator to compute the compliance and conductance of the chamber alone. Then by subtracting, the compliance and conductance for the surface is obtained.

  20. Cochlear bionic acoustic metamaterials

    Science.gov (United States)

    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.

  1. Wave Heating of the Solar Chromosphere

    Indian Academy of Sciences (India)

    Wolfgang Kalkofen

    2008-03-01

    The nonmagnetic interior of supergranulation cells has been thought since the 1940s to be heated by the dissipation of acoustic waves. But all attempts to measure the acoustic flux have failed to show sufficient energy for chromospheric heating. Recent space observations with TRACE, for example, have found 10% or less of the necessary flux. To explain the missing energy it has been speculated that the nonmagnetic chromosphere is heated mainly by waves related to the magnetic field. If that were correct, the whole chromosphere, magnetic as well as nonmagnetic, would be heated mainly by waves related to the magnetic field. But contrary to expectation, the radiation emerging from the nonmagnetic chromosphere shows none of the signatures of magnetic waves, only those of acoustic waves. Nearly all the heating of the nonmagnetic chromosphere must therefore be due to acoustic waves. In the magnetic network on the boundary of supergranulation cells, on the other hand, the small filling factor of the magnetic field in the photosphere implies that only a small fraction of the wave flux that travels upward to heat the chromosphere can be channeled by the magnetic field. Hence, while some of the energy that is dissipated in the magnetic network is in the form of magnetic waves, most of it must be in the form of acoustic waves. Thus, the quiet solar chromosphere, instead of being heated mainly by magneticwaves throughout, must be heated mainly by acoustic waves throughout. The full wave flux heating the quiet chromosphere must travel through the photosphere. In the nonmagnetic medium, this flux is essentially all in the form of acoustic waves; TRACE registers at most 10% of it, perhaps because of limited spatial resolution.

  2. Acoustic Force Density Acting on Inhomogeneous Fluids in Acoustic Fields

    DEFF Research Database (Denmark)

    Karlsen, Jonas Tobias; Augustsson, Per; Bruus, Henrik

    2016-01-01

    We present a theory for the acoustic force density acting on inhomogeneous fluids in acoustic fields on time scales that are slow compared to the acoustic oscillation period. The acoustic force density depends on gradients in the density and compressibility of the fluid. For microfluidic systems...

  3. EVALUATION OF ACOUSTIC FORCES ON A PARTICLE IN AEROSOL MEDIUM

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S; Richard Dimenna, R

    2007-09-27

    The acoustic force exerted on a solid particle was evaluated to develop a fundamental understanding of the critical physical parameters or constraints affecting particle motion and capture in a collecting device. The application of an acoustic force to the collection of a range of submicron-to-micron particles in a highly turbulent airflow stream laden with solid particles was evaluated in the presence of other assisting and competing forces. This scoping estimate was based on the primary acoustic force acting directly on particles in a dilute aerosol system, neglecting secondary interparticle effects such as agglomeration of the sub-micron particles. A simplified analysis assuming a stable acoustic equilibrium with an infinite sound speed in the solid shows that for a solid-laden air flow in the presence of a standing wave, particles will move toward the nearest node. The results also show that the turbulent drag force on a 1-{micro}m particle resulting from eddy motion is dominant when compared with the electrostatic force or the ultrasonic acoustic force. At least 180 dB acoustic pressure level at 1 MHz is required for the acoustic force to be comparable to the electrostatic or turbulent drag forces in a high-speed air stream. It is noted that particle size and pressure amplitude are dominant parameters for the acoustic force. When acoustic pressure level becomes very large, the acoustic energy will heat up the surrounding air medium, which may cause air to expand. With an acoustic power of about 600 watts applied to a 2000-lpm air flow, the air temperature can increase by as much as 15 C at the exit of the collector.

  4. Flat acoustic lens by acoustic grating with curled slits

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Pai; Xiao, Bingmu; Wu, Ying, E-mail: ying.wu@kaust.edu.sa

    2014-10-03

    We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry–Perot resonance. - Highlights: • Expression of transmission coefficient of an acoustic grating with curled slits. • Non-dispersive and tunable effective medium parameters for the acoustic grating. • A flat acoustic focusing lens with gradient index by using the acoustic grating.

  5. Acoustic mapping velocimetry

    Science.gov (United States)

    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.

  6. Underwater Applications of Acoustical Holography

    Directory of Open Access Journals (Sweden)

    P. C. Mehta

    1984-01-01

    Full Text Available The paper describes the basic technique of acoustical holography. Requirements for recording the acoustical hologram are discussed with its ability for underwater imaging in view. Some practical systems for short-range and medium-range imaging are described. The advantages of acoustical holography over optical imaging, acoustical imaging and sonars are outlined.

  7. Predicting Acoustics in Class Rooms

    DEFF Research Database (Denmark)

    Christensen, Claus Lynge; Rindel, Jens Holger

    2005-01-01

    Typical class rooms have fairly simple geometries, even so room acoustics in this type of room is difficult to predict using today's room acoustic computer modeling software. The reasons why acoustics of class rooms are harder to predict than acoustics of complicated concert halls might...

  8. THz Acoustic Spectroscopy by using Double Quantum Wells and Ultrafast Optical Spectroscopy

    Science.gov (United States)

    Wei, Fan Jun; Yeh, Yu-Hsiang; Sheu, Jinn-Kong; Lin, Kung-Hsuan

    2016-06-01

    GaN is a pivotal material for acoustic transducers and acoustic spectroscopy in the THz regime, but its THz phonon properties have not been experimentally and comprehensively studied. In this report, we demonstrate how to use double quantum wells as a THz acoustic transducer for measuring generated acoustic phonons and deriving a broadband acoustic spectrum with continuous frequencies. We experimentally investigated the sub-THz frequency dependence of acoustic attenuation (i.e., phonon mean-free paths) in GaN, in addition to its physical origins such as anharmonic scattering, defect scattering, and boundary scattering. A new upper limit of attenuation caused by anharmonic scattering, which is lower than previously reported values, was obtained. Our results should be noteworthy for THz acoustic spectroscopy and for gaining a fundamental understanding of heat conduction.

  9. Dynamic response analysis of an aircraft structure under thermal-acoustic loads

    Science.gov (United States)

    Cheng, H.; Li, H. B.; Zhang, W.; Wu, Z. Q.; Liu, B. R.

    2016-09-01

    Future hypersonic aircraft will be exposed to extreme combined environments includes large magnitude thermal and acoustic loads. It presents a significant challenge for the integrity of these vehicles. Thermal-acoustic test is used to test structures for dynamic response and sonic fatigue due to combined loads. In this research, the numerical simulation process for the thermal acoustic test is presented, and the effects of thermal loads on vibro-acoustic response are investigated. To simulate the radiation heating system, Monte Carlo theory and thermal network theory was used to calculate the temperature distribution. Considering the thermal stress, the high temperature modal parameters are obtained with structural finite element methods. Based on acoustic finite element, modal-based vibro-acoustic analysis is carried out to compute structural responses. These researches are very vital to optimum thermal-acoustic test and structure designs for future hypersonic vehicles structure

  10. Acoustical experiment of yogurt fermentation process.

    Science.gov (United States)

    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

  11. Thermoacoustic Stirling Heat Pump Working as a Heater

    Science.gov (United States)

    Bassem, Mohamed Mehdi; Ueda, Yuki; Akisawa, Atsushi

    2011-10-01

    A prototype thermoacoustic heat pump working as a heater was demonstrated. The heat pump was composed of an acoustic driver, a branched tube, and a looped tube containing a regenerator; the looped tube was connected to the acoustic driver via the branched tube, and the regenerator consisted of many narrow flow channels. The measurement results of the acoustic impedance inside the looped tube indicated that the energy conversion of the acoustic power flow into the acoustic heat flow in the regenerator occurred through the inherently efficient Stirling cycle. Moreover, the heat pump generated a hot temperature of 370 °C, corresponding to a temperature lift along the regenerator of 340 °C.

  12. Measurement of the acoustic-to-optical phonon coupling in multicomponent systems

    NARCIS (Netherlands)

    Caretta, Antonio; Donker, Michiel C.; Perdok, Diederik W.; Abbaszadeh, Davood; Polyakov, Alexey O.; Havenith, Remco W. A.; Palstra, Thomas T. M.; van Loosdrecht, Paul H. M.

    2015-01-01

    In this paper we investigate the acoustic-to-optical up-conversion phonon processes in a multicomponent system. These processes take place during heat transport and limit the efficiency of heat flow. By combining time-resolved optical and heat capacity experiments we quantify the thermal coupling co

  13. Damping-Growth Transition for Ion-Acoustic Waves in a Density Gradient

    DEFF Research Database (Denmark)

    D'Angelo, N.; Michelsen, Poul; Pécseli, Hans

    1975-01-01

    A damping-growth transition for ion-acoustic waves propagating in a nonuniform plasma (e-folding length for the density ln) is observed at a wavelength λ∼2πln. This result supports calculations performed in connection with the problem of heating of the solar corona by ion-acoustic waves generated...

  14. Thermal and fluid dynamic analysis of partially premixed turbulent combustion driven by thermo acoustic effects

    NARCIS (Netherlands)

    Shahi, M.; Kok, J.B.W.; Pozarlik, A.K.; Sponfeldner, Thomas; Malcolm, M.J.; Pawelczyk, M.; Paosawatyangyong, B.

    2013-01-01

    Thermo-acoustic instability can be caused by the feedback mechanism between unsteady heat release, acoustic oscillations and flow perturbations. In a gas turbine combustor limit cycles of pressure oscillations at elevated temperatures generated by the unstable combustion process enhance the structur

  15. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... Request a patient kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms Side ... Question To Ask Treatment Options Back Overview Observation Radiation Surgery Choosing a healthcare provider Request a patient ...

  16. Thermal Acoustic Fatigue Apparatus

    Data.gov (United States)

    Federal Laboratory Consortium — The Thermal Acoustic Fatigue Apparatus (TAFA) is a progressive wave tube test facility that is used to test structures for dynamic response and sonic fatigue due to...

  17. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... resource Click to learn more... LOGIN EVENTS DONATE Home Learn Back Learn about acoustic neuroma AN Facts ... Vision & Values Leadership & Staff Annual Reports Shop ANA Home Learn Educational Video OrangeTheory AN Warriors Laurie of ...

  18. Acoustic imaging system

    Science.gov (United States)

    Smith, Richard W.

    1979-01-01

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

  19. An acoustic invisible gateway

    CERN Document Server

    Zhu, Yi-Fan; Liang, Bin; Kan, Wei-Wei; Yang, Jun; Cheng, Jian-Chun

    2015-01-01

    The recently-emerged concept of "invisible gateway" with the extraordinary capability to block the waves but allow the passage of other entities has attracted great attentions due to the general interests in illusion devices. However, the possibility to realize such a fascinating phenomenon for acoustic waves has not yet been explored, which should be of paramount significance for acoustical applications but would necessarily involve experimental difficulty. Here we design and experimentally demonstrate an acoustic invisible gateway (AIG) capable of concealing a channel under the detection of sound. Instead of "restoring" a whole block of background medium by using transformation acoustics that inevitably requires complementary or restoring media with extreme parameters, we propose an inherently distinct methodology that only aims at engineering the surface impedance at the "gate" to mimic a rigid "wall" and can be conveniently implemented by decorating meta-structures behind the channel. Such a simple yet ef...

  20. Acoustics Noise Test Cell

    Data.gov (United States)

    Federal Laboratory Consortium — The Acoustic Noise Test Cell at the NASA/Caltech Jet Propulsion Laboratory (JPL) is located adjacent to the large vibration system; both are located in a class 10K...

  1. Acoustic Igniter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An acoustic igniter eliminates the need to use electrical energy to drive spark systems to initiate combustion in liquid-propellant rockets. It does not involve the...

  2. Acoustic Igniter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An acoustic igniter eliminates the need to use electrical energy to drive spark systems to initiate combustion in liquid-propellant rockets. It does not involve the...

  3. Acoustic MIMO signal processing

    CERN Document Server

    Huang, Yiteng; Chen, Jingdong

    2006-01-01

    A timely and important book addressing a variety of acoustic signal processing problems under multiple-input multiple-output (MIMO) scenarios. It uniquely investigates these problems within a unified framework offering a novel and penetrating analysis.

  4. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... ANA About ANA Mission, Vision & Values Shop ANA Leadership & Staff Annual Reports Acoustic Neuroma Association 600 Peachtree ... info@ANAUSA.org About ANA Mission, Vision & Values Leadership & Staff Annual Reports Shop ANA Home Learn Educational ...

  5. Acoustics Noise Test Cell

    Data.gov (United States)

    Federal Laboratory Consortium — The Acoustic Noise Test Cell at the NASA/Caltech Jet Propulsion Laboratory (JPL) is located adjacent to the large vibration system; both are located in a class 10K...

  6. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... Choosing a healthcare provider Request a patient kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms Side effects Question To Ask Treatment Options Back Overview Observation Radiation Surgery Choosing a ...

  7. Acoustic imaging system

    Science.gov (United States)

    Kendall, J. M., Jr.

    1977-01-01

    Tool detects noise sources by scanning sound "scene" and displaying relative location of noise-producing elements in area. System consists of ellipsoidal acoustic mirror and microphone and a display device.

  8. Symptoms of Acoustic Neuroma

    Science.gov (United States)

    ... Programs & Services Search ANAUSA.org Connect with us! Symptoms of Acoustic Neuroma Each heading slides to reveal more information. Early Symptoms Early Symptoms Early symptoms are easily overlooked, thus making diagnosis ...

  9. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... a patient kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms Side effects ... To Ask Treatment Options Back Overview Observation Radiation Surgery Choosing a healthcare provider Request a patient kit ...

  10. Autonomous Acoustic Receiver System

    Data.gov (United States)

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

  11. Acoustic Neuroma Educational Video

    Medline Plus

    Full Text Available ... provider Request a patient kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms ... effects Question To Ask Treatment Options Back Overview Observation Radiation Surgery Choosing a healthcare provider Request a ...

  12. Principles of musical acoustics

    CERN Document Server

    Hartmann, William M

    2013-01-01

    Principles of Musical Acoustics focuses on the basic principles in the science and technology of music. Musical examples and specific musical instruments demonstrate the principles. The book begins with a study of vibrations and waves, in that order. These topics constitute the basic physical properties of sound, one of two pillars supporting the science of musical acoustics. The second pillar is the human element, the physiological and psychological aspects of acoustical science. The perceptual topics include loudness, pitch, tone color, and localization of sound. With these two pillars in place, it is possible to go in a variety of directions. The book treats in turn, the topics of room acoustics, audio both analog and digital, broadcasting, and speech. It ends with chapters on the traditional musical instruments, organized by family. The mathematical level of this book assumes that the reader is familiar with elementary algebra. Trigonometric functions, logarithms and powers also appear in the book, but co...

  13. Anal acoustic reflectometry

    DEFF Research Database (Denmark)

    Mitchell, Peter J; Klarskov, Niels; Telford, Karen J

    2011-01-01

    Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis.......Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis....

  14. Anal acoustic reflectometry

    DEFF Research Database (Denmark)

    Mitchell, Peter J; Klarskov, Niels; Telford, Karen J;

    2011-01-01

    Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis.......Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis....

  15. Acoustic Communications (ACOMMS) ATD

    Science.gov (United States)

    2016-06-14

    Communications , Computers , Intelligence, Surveillance, and Reconnaissance (C4ISR) systems that "capture, synthesize and distribute near-real time information to...Acoustic Communications (ACOMMS) ATD Tam Nguyen 2531 Jefferson Davis Hwy Arlington, VA 22242 phone: (703) 604-6013 ext 520 fax: (703) 604-6056...email: NguyenTL@navsea.navy.mil Award # N0001499PD30007 LONG-TERM GOALS The goal of the recently completed Acoustic Communications Advanced

  16. Acoustical studies on corrugated tubes

    Science.gov (United States)

    Balaguru, Rajavel

    Corrugated tubes and pipes offer greater global flexibility combined with local rigidity. They are used in numerous engineering applications such as vacuum cleaner hosing, air conditioning systems of aircraft and automobiles, HVAC control systems of heating ducts in buildings, compact heat exchangers, medical equipment and offshore gas and oil transportation flexible riser pipelines. Recently there has been a renewed research interest in analyzing the flow through a corrugated tube to understand the underlying mechanism of so called whistling, although the whistling in such a tube was identified in early twentieth century. The phenomenon of whistling in a corrugated tube is interesting because an airflow through a smooth walled tube of similar dimensions will not generate any whistling tones. Study of whistling in corrugated tubes is important because, it not only causes an undesirable noise problem but also results in flow-acoustic coupling. Such a coupling can cause significant structural vibrations due to flow-acoustic-structure interaction. This interaction would cause flow-induced vibrations that could result in severe damage to mechanical systems having corrugated tubes. In this research work, sound generation (whistling) in corrugated tubes due to airflow is analyzed using experimental as well as Computational Fluid Dynamics-Large Eddy Simulation (CFD-LES) techniques. Sound generation mechanisms resulting in whistling have been investigated. The whistling in terms of frequencies and sound pressure levels for different flow velocities are studied. The analytical and experimental studies are carried out to understand the influence of various parameters of corrugated tubes such as cavity length, cavity width, cavity depth, pitch, Reynolds numbers and number of corrugations. The results indicate that there is a good agreement between theoretically calculated, computationally predicted and experimentally measured whistling frequencies and sound pressure levels

  17. Acoustic vector sensor signal processing

    Institute of Scientific and Technical Information of China (English)

    SUN Guiqing; LI Qihu; ZHANG Bin

    2006-01-01

    Acoustic vector sensor simultaneously, colocately and directly measures orthogonal components of particle velocity as well as pressure at single point in acoustic field so that is possible to improve performance of traditional underwater acoustic measurement devices or detection systems and extends new ideas for solving practical underwater acoustic engineering problems. Although acoustic vector sensor history of appearing in underwater acoustic area is no long, but with huge and potential military demands, acoustic vector sensor has strong development trend in last decade, it is evolving into a one of important underwater acoustic technology. Under this background, we try to review recent progress in study on acoustic vector sensor signal processing, such as signal detection, DOA estimation, beamforming, and so on.

  18. Electron heat flux instability

    Science.gov (United States)

    Saeed, Sundas; Sarfraz, M.; Yoon, P. H.; Lazar, M.; Qureshi, M. N. S.

    2017-02-01

    The heat flux instability is an electromagnetic mode excited by a relative drift between the protons and two-component core-halo electrons. The most prominent application may be in association with the solar wind where drifting electron velocity distributions are observed. The heat flux instability is somewhat analogous to the electrostatic Buneman or ion-acoustic instability driven by the net drift between the protons and bulk electrons, except that the heat flux instability operates in magnetized plasmas and possesses transverse electromagnetic polarization. The heat flux instability is also distinct from the electrostatic counterpart in that it requires two electron species with relative drifts with each other. In the literature, the heat flux instability is often called the 'whistler' heat flux instability, but it is actually polarized in the opposite sense to the whistler wave. This paper elucidates all of these fundamental plasma physical properties associated with the heat flux instability starting from a simple model, and gradually building up more complexity towards a solar wind-like distribution functions. It is found that the essential properties of the instability are already present in the cold counter-streaming electron model, and that the instability is absent if the protons are ignored. These instability characteristics are highly reminiscent of the electron firehose instability driven by excessive parallel temperature anisotropy, propagating in parallel direction with respect to the ambient magnetic field, except that the free energy source for the heat flux instability resides in the effective parallel pressure provided by the counter-streaming electrons.

  19. Non-invasive photo acoustic approach for human bone diagnosis.

    Science.gov (United States)

    Thella, Ashok Kumar; Rizkalla, James; Helmy, Ahdy; Suryadevara, Vinay Kumar; Salama, Paul; Rizkalla, Maher

    2016-12-01

    The existing modalities of bone diagnosis including X-ray and ultrasound may cite drawback in some cases related to health issues and penetration depth, while the ultrasound modality may lack image quality. Photo acoustic approach however, provides light energy to the acoustic wave, enabling it to activate and respond according to the propagating media (which is type of bones in this case). At the same time, a differential temperature change may result in the bio heat response, resulting from the heat absorbed across the multiple materials under study. In this work, we have demonstrated the features of using photo acoustic modality in order to non-invasively diagnose the type of human bones based on their electrical, thermal, and acoustic properties that differentiate the output response of each type. COMSOL software was utilized to combine both acoustic equations and bio heat equations, in order to study both the thermal and acoustic responses through which the differential diagnosis can be obtained. In this study, we solved both the acoustic equation and bio heat equations for four types of bones, bone (cancellous), bone (cortical), bone marrow (red), and bone marrow (yellow). 1 MHz acoustic source frequency was chosen and 10(5) W/m(2) power source was used in the simulation. The simulation tested the dynamic response of the wave over a distance of 5 cm from each side for the source. Near 2.4 cm was detected from simulation from each side of the source with a temperature change of within 0.5 K for various types of bones, citing a promising technique for a practical model to detect the type of bones via the differential temperature as well as the acoustic was response via the multiple materials associated with the human bones (skin and blood). The simulation results suggest that the PA technique may be applied to non-invasive diagnosis for the different types of bones, including cancerous bones. A practical model for detecting both the temperature change via

  20. Thermodynamics of Acoustic Black Holes in Two Dimensions

    Directory of Open Access Journals (Sweden)

    Baocheng Zhang

    2016-01-01

    Full Text Available It is well-known that the thermal Hawking-like radiation can be emitted from the acoustic horizon, but the thermodynamic-like understanding for acoustic black holes was rarely made. In this paper, we will show that the kinematic connection can lead to the dynamic connection at the horizon between the fluid and gravitational models in two dimensions, which implies that there exists the thermodynamic-like description for acoustic black holes. Then, we discuss the first law of thermodynamics for the acoustic black hole via an intriguing connection between the gravitational-like dynamics of the acoustic horizon and thermodynamics. We obtain a universal form for the entropy of acoustic black holes, which has an interpretation similar to the entropic gravity. We also discuss the specific heat and find that the derivative of the velocity of background fluid can be regarded as a novel acoustic analogue of the two-dimensional dilaton potential, which interprets why the two-dimensional fluid dynamics can be connected to the gravitational dynamics but it is difficult for four-dimensional case. In particular, when a constraint is added for the fluid, the analogue of a Schwarzschild black hole can be realized.

  1. Thermodynamics of acoustic black holes in two dimensions

    CERN Document Server

    Zhang, Baocheng

    2016-01-01

    It is well-known that the thermal Hawking-like radiation can be emitted from the acoustic horizon, but the thermodynamic-like understanding for acoustic black holes was rarely made. In this paper, we will show that the kinematic connection can lead to the dynamic connection at the horizon between the fluid and gravitational models in two dimension, which implies that there exists the thermodynamic-like description for acoustic black holes. Then, we discuss the first law of thermodynamics for the acoustic black hole via an intriguing connection between the gravitational-like dynamics of the acoustic horizon and thermodynamics, as well-built in the gravity theory. We obtain a universal form for the entropy of acoustic black holes, which has an interpretation similar to the entropic gravity. We also discuss the specific heat, and find that the derivative of the velocity of background fluid can be regarded as a novel acoustic analogue of the two-dimensional dilaton potential, which interprets why the two-dimensio...

  2. Theory and application of scanning electron acoustic microscopy

    Science.gov (United States)

    Cantrell, John H.; Qian, Menglu; Chen, Ruiyi; Yost, William T.

    1992-01-01

    A three-dimensional theoretical model based on the application of the thermal conduction and Navier equations to a chopped electron beam incident on a disk specimen is used to obtain the particle displacement field in the specimen. The results lead to a consideration of the signal generation, spatial resolution, and contrast mechanisms in scanning electron acoustic microscopy (SEAM). The model suggests that the time-variant heat source produced by the beam chopping generates driving source, thermal wave, and acoustic wave displacements simultaneously in the specimen. Evidence of the correctness of the prediction is obtained from the mathematically similar problem of pulsed laser light injection into a tank of water. High speed Schlieren photographs taken following laser injection show the simultaneous evolution of thermal and acoustic waveforms. Examples of contrast reversal, stress-induced contrast, and acoustic zone contrast and resolution with SEAM are presented and explained in terms of the model features.

  3. Numerical Modeling of Electroacoustic Logging Including Joule Heating

    Science.gov (United States)

    Plyushchenkov, Boris D.; Nikitin, Anatoly A.; Turchaninov, Victor I.

    It is well known that electromagnetic field excites acoustic wave in a porous elastic medium saturated with fluid electrolyte due to electrokinetic conversion effect. Pride's equations describing this process are written in isothermal approximation. Update of these equations, which allows to take influence of Joule heating on acoustic waves propagation into account, is proposed here. This update includes terms describing the initiation of additional acoustic waves excited by thermoelastic stresses and the heat conduction equation with right side defined by Joule heating. Results of numerical modeling of several problems of propagation of acoustic waves excited by an electric field source with and without consideration of Joule heating effect in their statements are presented. From these results, it follows that influence of Joule heating should be taken into account at the numerical simulation of electroacoustic logging and at the interpretation of its log data.

  4. Acoustic comfort in eating establishments

    DEFF Research Database (Denmark)

    Svensson, David; Jeong, Cheol-Ho; Brunskog, Jonas

    2014-01-01

    The subjective concept of acoustic comfort in eating establishments has been investigated in this study. The goal was to develop a predictive model for the acoustic comfort, by means of simple objective parameters, while also examining which other subjective acoustic parameters could help explain...... the feeling of acoustic comfort. Through several layers of anal ysis, acoustic comfort was found to be rather complex, and could not be explained entirely by common subjective parameters such as annoyance, intelligibility or privacy. A predictive model for the mean acoustic comfort for an eating establishment...

  5. Interactions in an acoustic world

    CERN Document Server

    Simaciu, Ion; Borsos, Zoltan; Bradac, Mariana

    2016-01-01

    The present paper aims to complete an earlier paper where the acoustic world was introduced. This is accomplished by analyzing the interactions which occur between the inhomogeneities of the acoustic medium, which are induced by the acoustic vibrations traveling in the medium. When a wave packet travels in a medium, the medium becomes inhomogeneous. The spherical wave packet behaves like an acoustic spherical lens for the acoustic plane waves. According to the principle of causality, there is an interaction between the wave and plane wave packet. In specific conditions the wave packet behaves as an acoustic black hole.

  6. Embedded and conventional ultrasonic sensors for monitoring acoustic emission during thermal fatigue

    Science.gov (United States)

    Trujillo, Blaine; Zagrai, Andrei

    2016-04-01

    Acoustic emission is widely used for monitoring pressure vessels, pipes, critical infrastructure, as well as land, sea and air vehicles. It is one of dominant approaches to explore material degradation under fatigue and events leading to material fracture. Addressing a recent interest in structural health monitoring of space vehicles, a need has emerged to evaluate material deterioration due to thermal fatigue during spacecraft atmospheric reentry. Thermal fatigue experiments were conducted, in which aluminum plates were subjected to localized heating and acoustic emission was monitoring by embedded and conventional acoustic emission sensors positioned at various distances from a heat source. At the same time, surface temperature of aluminum plates was monitored using an IR camera. Acoustic emission counts collected by embedded sensors were compared to counts measured with conventional acoustic emission sensors. Both types of sensors show noticeable increase of acoustic emission activity as localized heating source was applied to aluminum plates. Experimental data demonstrate correlation between temperature increase on the surface of the plates and increase in measured acoustic emission activity. It is concluded that under particular conditions, embedded piezoelectric wafer active sensors can be used for acoustic emission monitoring of thermally-induced structural degradation.

  7. High-frequency seafloor acoustics

    National Research Council Canada - National Science Library

    Jackson, D. R; Richardson, M. D

    2007-01-01

    This title provides access to experimental data, theory, and models relevant to high-frequency seafloor acoustics and will be of interest to sonar engineers and researchers working in underwater acoustics...

  8. A Century of Acoustic Metrology

    DEFF Research Database (Denmark)

    Rasmussen, Knud

    1998-01-01

    The development in acoustic measurement technique over the last century is reviewed with special emphasis on the metrological aspect.......The development in acoustic measurement technique over the last century is reviewed with special emphasis on the metrological aspect....

  9. Advanced Active Acoustics Lab (AAAL)

    Data.gov (United States)

    Federal Laboratory Consortium — The Advanced Active Acoustics Lab (AAAL) is a state-of-the-art Undersea Warfare (USW) acoustic data analysis facility capable of both active and passive underwater...

  10. Acoustic detection of pneumothorax

    Science.gov (United States)

    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 (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 (ppneumothorax states (pPneumothorax 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 (pPneumothorax 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.

  11. Practical acoustic emission testing

    CERN Document Server

    2016-01-01

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

  12. Acoustics waves and oscillations

    CERN Document Server

    Sen, S.N.

    2013-01-01

    Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...

  13. Acoustics of courtyard theatres

    Institute of Scientific and Technical Information of China (English)

    WANG Jiqing

    2008-01-01

    The traditional Chinese theatre was often built with a courtyard. In such open-top space, the absence of a roof would mean little reverberation and non-diffused sound field.Acoustically the situation is quite different from that of any enclosed space. The refore, theclassic room acoustics, such as Sabine reverberation formula, would no longer be applicable due to the lack of sound reflections from the ceiling. As the parameter of reverberation time T30 shows the decay rate only, it would not properly characterize the prominent change in the fine structure of the echogram, particularly in case of a large reduction of reflections during the decay process. The sense of reverbrance in a courtyard space would differ noticeably from that of the equivalent 3D-T30 in an enclosed space. Based upon the characteristic analysis of the sound field in an open-top space, this paper presents a preliminary study on the acoustics of the courtyard theatres.

  14. Acoustically Induced Vibration of Structures: Reverberant Vs. Direct Acoustic Testing

    Science.gov (United States)

    Kolaini, Ali R.; O'Connell, Michael R.; Tsoi, Wan B.

    2009-01-01

    Large reverberant chambers have been used for several decades in the aerospace industry to test larger structures such as solar arrays and reflectors to qualify and to detect faults in the design and fabrication of spacecraft and satellites. In the past decade some companies have begun using direct near field acoustic testing, employing speakers, for qualifying larger structures. A limited test data set obtained from recent acoustic tests of the same hardware exposed to both direct and reverberant acoustic field testing has indicated some differences in the resulting structural responses. In reverberant acoustic testing, higher vibration responses were observed at lower frequencies when compared with the direct acoustic testing. In the case of direct near field acoustic testing higher vibration responses appeared to occur at higher frequencies as well. In reverberant chamber testing and direct acoustic testing, standing acoustic modes of the reverberant chamber or the speakers and spacecraft parallel surfaces can strongly couple with the fundamental structural modes of the test hardware. In this paper data from recent acoustic testing of flight hardware, that yielded evidence of acoustic standing wave coupling with structural responses, are discussed in some detail. Convincing evidence of the acoustic standing wave/structural coupling phenomenon will be discussed, citing observations from acoustic testing of a simple aluminum plate. The implications of such acoustic coupling to testing of sensitive flight hardware will be discussed. The results discussed in this paper reveal issues with over or under testing of flight hardware that could pose unanticipated structural and flight qualification issues. Therefore, it is of paramount importance to understand the structural modal coupling with standing acoustic waves that has been observed in both methods of acoustic testing. This study will assist the community to choose an appropriate testing method and test setup in

  15. [INVITED] Laser generation and detection of ultrafast shear acoustic waves in solids and liquids

    Science.gov (United States)

    Pezeril, Thomas

    2016-09-01

    The aim of this article is to provide an overview of the up-to-date findings related to ultrafast shear acoustic waves. Recent progress obtained for the laser generation and detection of picosecond shear acoustic waves in solids and liquids is reviewed. Examples in which the transverse isotropic symmetry of the sample structure is broken in order to permit shear acoustic wave generation through sudden laser heating are described in detail. Alternative photo-induced mechanisms for ultrafast shear acoustic generation in metals, semiconductors, insulators, magnetostrictive, piezoelectric and electrostrictive materials are reviewed as well. With reference to key experiments, an all-optical technique employed to probe longitudinal and shear structural dynamics in the GHz frequency range in ultra-thin liquid films is described. This technique, based on specific ultrafast shear acoustic transducers, has opened new perspectives that will be discussed for ultrafast shear acoustic probing of viscoelastic liquids at the nanometer scale.

  16. Investigation on influencing factors of acoustic streaming in thermoacoustic waveguides with slowly varying cross-section

    Institute of Scientific and Technical Information of China (English)

    FAN Yuxian; LIU Ke; YANG Jun

    2012-01-01

    The influencing factors of acoustic streaming in thermoacoustic waveguides with slowly varying cross-section are analyzed based on theoretical analysis and numerical simulation. The distribution curves of acoustic streaming velocity in waveguides with different characteristic scales are presented in several specific cases. The results show that appropriate forms of varying cross-section can strengthen or weaken acoustic streaming for specific acoustic fields and the thermophysical parameters have no effect on this part. In addition, the influence of time-average temperature distribution on acoustic streaming is substantial in tubes with a width of the order of the thermal penetration depth. Without time-average temperature distribution, the effect of heat conduction on acoustic streaming is great in tubes whose width is an order of about 10 to 20 times the viscous penetration depth.

  17. Nonlinear acoustics in biomedical ultrasound

    Science.gov (United States)

    Cleveland, Robin O.

    2015-10-01

    Ultrasound is widely used to image inside the body; it is also used therapeutically to treat certain medical conditions. In both imaging and therapy applications the amplitudes employed in biomedical ultrasound are often high enough that nonlinear acoustic effects are present in the propagation: the effects have the potential to be advantageous in some scenarios but a hindrance in others. In the case of ultrasound imaging the nonlinearity produces higher harmonics that result in images of greater quality. However, nonlinear effects interfere with the imaging of ultrasound contrast agents (typically micron sized bubbles with a strong nonlinear response of their own) and nonlinear effects also result in complications when derating of pressure measurements in water to in situ values in tissue. High intensity focused ultrasound (HIFU) is emerging as a non-invasive therapeutic modality which can result in thermal ablation of tissue. For thermal ablation, the extra effective attenuation resulting from nonlinear effects can result in enhanced heating of tissue if shock formation occurs in the target region for ablation - a highly desirable effect. However, if nonlinearity is too strong it can also result in undesired near-field heating and reduced ablation in the target region. The disruption of tissue (histotripsy) and fragmentation of kidney stones (lithotripsy) exploits shock waves to produce mechanically based effects, with minimal heating present. In these scenarios it is necessary for the waves to be of sufficient amplitude that a shock exists when the waveform reaches the target region. This talk will discuss how underlying nonlinear phenomenon act in all the diagnostic and therapeutic applications described above.

  18. Acoustic classification of dwellings

    DEFF Research Database (Denmark)

    Berardi, Umberto; Rasmussen, Birgit

    2014-01-01

    insulation performance, national schemes for sound classification of dwellings have been developed in several European countries. These schemes define acoustic classes according to different levels of sound insulation. Due to the lack of coordination among countries, a significant diversity in terms...... of descriptors, number of classes, and class intervals occurred between national schemes. However, a proposal “acoustic classification scheme for dwellings” has been developed recently in the European COST Action TU0901 with 32 member countries. This proposal has been accepted as an ISO work item. This paper...

  19. Room Acoustical Fields

    CERN Document Server

    Mechel, Fridolin

    2013-01-01

    This book presents the theory of room acoustical fields and revises the Mirror Source Methods for practical computational use, emphasizing the wave character of acoustical fields.  The presented higher methods include the concepts of “Mirror Point Sources” and “Corner sources which allow for an excellent approximation of complex room geometries and even equipped rooms. In contrast to classical description, this book extends the theory of sound fields describing them by their complex sound pressure and the particle velocity. This approach enables accurate descriptions of interference and absorption phenomena.

  20. Acoustic black holes

    CERN Document Server

    Visser, M

    1999-01-01

    Acoustic propagation in a moving fluid provides a conceptually clean and powerful analogy for understanding black hole physics. As a teaching tool, the analogy is useful for introducing students to both General Relativity and fluid mechanics. As a research tool, the analogy helps clarify what aspects of the physics are kinematics and what aspects are dynamics. In particular, Hawking radiation is a purely kinematical effect, whereas black hole entropy is intrinsically dynamical. Finally, I discuss the fact that with present technology acoustic Hawking radiation is almost experimentally testable.

  1. Broadband asymmetric acoustic transmission through an acoustic prism

    Science.gov (United States)

    Song, Ailing; Chen, Tianning; Wang, Xiaopeng; Xi, Yanhui

    2017-08-01

    Narrow bandwidth and complex structure are the main shortcomings of the existing asymmetric acoustic transmission devices. In this letter, a simple broadband asymmetric acoustic transmission device is proposed by using an acoustic prism filled with xenon gas. The sound pressure field distributions, the transmission spectra, and the prism angle effect are numerically investigated by using finite element method. The proposed device can always realize asymmetric acoustic transmission for the wave frequency larger than 480 Hz because the wave paths are not influenced by the wave frequencies. The asymmetric acoustic transmission is attributed to normal refraction and total reflection occur at different interfaces. Besides, relatively high transmission efficiency is realized due to the similar impedance between the acoustic prism and background. And the transmitted wave direction can be controlled freely by changing the prism angle. Our design provides a simple method to obtain broadband asymmetric acoustic transmission device and has potentials in many applications, such as noise control and medical ultrasound.

  2. Heat Waves

    Science.gov (United States)

    Heat Waves Dangers we face during periods of very high temperatures include: Heat cramps: These are muscular pains and ... having trouble with the heat. If a heat wave is predicted or happening… - Slow down. Avoid strenuous ...

  3. Heat Islands

    Science.gov (United States)

    EPA's Heat Island Effect Site provides information on heat islands, their impacts, mitigation strategies, related research, a directory of heat island reduction initiatives in U.S. communities, and EPA's Heat Island Reduction Program.

  4. Evoked acoustic emission

    DEFF Research Database (Denmark)

    Elberling, C; Parbo, J; Johnsen, N J;

    1985-01-01

    Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has onl...

  5. Deep Water Ocean Acoustics

    Science.gov (United States)

    2016-08-03

    Award No.: N00014-14-C-0172 Report No. QSR-14C0172-Ocean Acoustics-063016 Prepared for: Office of Naval Research For the period: April 1...The source level in this overlay is a free parameter (but is estimated to be ~215 dB) re 1uPa2/m2). This agreement is exceptional. It shows the dip

  6. Indigenous Acoustic Detection.

    Science.gov (United States)

    1982-01-26

    considerable distances, and they act as good sensors of human presence. Though singing insects are ubiquitous in warm areas, even in the desert ( Nevo and...methodology. DTIC. CD-58-PL. Lloyd, J. E. 1981. Personnel communication. Nevo , E. and S. A. Blondheim. 1972. Acoustic isolation in the speciation of

  7. Evoked acoustic emission

    DEFF Research Database (Denmark)

    Elberling, C; Parbo, J; Johnsen, N J;

    1985-01-01

    Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has only...

  8. Deep Water Ocean Acoustics

    Science.gov (United States)

    2015-04-15

    sound speed profile is range-independent; since there is little expectation there will be significant mesoscale phenomenon given the lack of solar ...34 Journal of the Acoustical Society of America 93 (4), 1736-1742 (1993). 2 Chris H. Harrison and Martin Siderius, "Effective Parameters for Matched

  9. Underwater Acoustic Networking Techniques

    CERN Document Server

    Otnes, Roald; Casari, Paolo; Goetz, Michael; Husøy, Thor; Nissen, Ivor; Rimstad, Knut; van Walree, Paul; Zorzi, Michele

    2012-01-01

    This literature study presents an overview of underwater acoustic networking. It provides a background and describes the state of the art of all networking facets that are relevant for underwater applications. This report serves both as an introduction to the subject and as a summary of existing protocols, providing support and inspiration for the development of network architectures.

  10. Holograms for acoustics

    Science.gov (United States)

    Melde, Kai; Mark, Andrew G.; Qiu, Tian; Fischer, Peer

    2016-09-01

    Holographic techniques are fundamental to applications such as volumetric displays, high-density data storage and optical tweezers that require spatial control of intricate optical or acoustic fields within a three-dimensional volume. The basis of holography is spatial storage of the phase and/or amplitude profile of the desired wavefront in a manner that allows that wavefront to be reconstructed by interference when the hologram is illuminated with a suitable coherent source. Modern computer-generated holography skips the process of recording a hologram from a physical scene, and instead calculates the required phase profile before rendering it for reconstruction. In ultrasound applications, the phase profile is typically generated by discrete and independently driven ultrasound sources; however, these can only be used in small numbers, which limits the complexity or degrees of freedom that can be attained in the wavefront. Here we introduce monolithic acoustic holograms, which can reconstruct diffraction-limited acoustic pressure fields and thus arbitrary ultrasound beams. We use rapid fabrication to craft the holograms and achieve reconstruction degrees of freedom two orders of magnitude higher than commercial phased array sources. The technique is inexpensive, appropriate for both transmission and reflection elements, and scales well to higher information content, larger aperture size and higher power. The complex three-dimensional pressure and phase distributions produced by these acoustic holograms allow us to demonstrate new approaches to controlled ultrasonic manipulation of solids in water, and of liquids and solids in air. We expect that acoustic holograms will enable new capabilities in beam-steering and the contactless transfer of power, improve medical imaging, and drive new applications of ultrasound.

  11. Controlling sound with acoustic metamaterials

    DEFF Research Database (Denmark)

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

    2016-01-01

    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......-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...

  12. Surface Acoustic Waves to Drive Plant Transpiration

    Science.gov (United States)

    Gomez, Eliot F.; Berggren, Magnus; Simon, Daniel T.

    2017-03-01

    Emerging fields of research in electronic plants (e-plants) and agro-nanotechnology seek to create more advanced control of plants and their products. Electronic/nanotechnology plant systems strive to seamlessly monitor, harvest, or deliver chemical signals to sense or regulate plant physiology in a controlled manner. Since the plant vascular system (xylem/phloem) is the primary pathway used to transport water, nutrients, and chemical signals—as well as the primary vehicle for current e-plant and phtyo-nanotechnology work—we seek to directly control fluid transport in plants using external energy. Surface acoustic waves generated from piezoelectric substrates were directly coupled into rose leaves, thereby causing water to rapidly evaporate in a highly localized manner only at the site in contact with the actuator. From fluorescent imaging, we find that the technique reliably delivers up to 6x more water/solute to the site actuated by acoustic energy as compared to normal plant transpiration rates and 2x more than heat-assisted evaporation. The technique of increasing natural plant transpiration through acoustic energy could be used to deliver biomolecules, agrochemicals, or future electronic materials at high spatiotemporal resolution to targeted areas in the plant; providing better interaction with plant physiology or to realize more sophisticated cyborg systems.

  13. Investigating broadband acoustic adsorption using rapid manufacturing

    Science.gov (United States)

    Godbold, O.

    The reduction of nuisance noise and the removal of unwanted sound modes within a room or component enclosure-area can be accomplished through the use of acoustic absorbers. Sound absorption can be achieved through conversion of the kinetic energy associated with pressure waves, into heat energy via viscous dissipation. This occurs within open porous materials, or by utilising resonant effects produced using simple cavity and orifice configurations. The manufacture of traditional porous and resonant absorbers is commonly realised using basic manufacturing techniques. These techniques restrict the geometry of a given resonant construction, and limit the configuration of porous absorbers. The aim of this work is to exploit new and emerging capabilities of Rapid Manufacturing (RM) to produce components with geometrical freedom, and apply it to the development of broadband acoustic absorption. New and novel absorber geometric configurations are identified and their absorption performance is determined. The capabilities and limitations of RM processes in reproducing these configurations are demonstrated. The geometric configuration of RM resonant absorbers is investigated. Cavity modifications aimed at damping the resonant effect by restricting the motion of cavity air, and adding increased viscous resistance are explored. Modifications relating to cavity shape, the addition of internal perforations and increased cavity surface area have all been shown to add acoustic resistance, thereby increasing the bandwidth of absorption. Decreasing the hydraulic radius of the cavity cross section and reducing internal feature dimensions provide improved resistance over conventional configurations..

  14. Initiation of acoustic emission in fluid-saturated sandstone samples

    Science.gov (United States)

    Lapshin, V. B.; Patonin, A. V.; Ponomarev, A. V.; Potanina, M. G.; Smirnov, V. B.; Stroganova, S. M.

    2016-07-01

    A rock behavior experiment with uniaxial compression revealed the effect of acoustic activity in loaded fluid-saturated Berea sandstone samples in response to an electric current. It is established that it is substantially intensified in periods of the current impact and decreases after its cut-off. The current impact also results in a growth of radial deformation indicating an increase in the sample volume. The effect of acoustic activation increases in response to increased heat emitted by the electric current during its flow through the sample, which allows the discovered effect to be explained by initiation of its destruction due to thermal expansion of the fluid in rock interstices and fissures.

  15. Flat acoustic lens by acoustic grating with curled slits

    KAUST Repository

    Peng, Pai

    2014-10-01

    We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry-Perot resonance.

  16. Manipulate acoustic waves by impedance matched acoustic metasurfaces

    Science.gov (United States)

    Wu, Ying; Mei, Jun; Aljahdali, Rasha

    We design a type of acoustic metasurface, which is composed of carefully designed slits in a rigid thin plate. The effective refractive indices of different slits are different but the impedances are kept the same as that of the host medium. Numerical simulations show that such a metasurface can redirect or reflect a normally incident wave at different frequencies, even though it is impedance matched to the host medium. We show that the underlying mechanisms can be understood by using the generalized Snell's law, and a unified analytic model based on mode-coupling theory. We demonstrate some simple realization of such acoustic metasurface with real materials. The principle is also extended to the design of planar acoustic lens which can focus acoustic waves. Manipulate acoustic waves by impedance matched acoustic metasurfaces.

  17. Acoustic properties of biodegradable nonwovens

    Science.gov (United States)

    Yilmaz, Nazire Deniz

    The purpose of this study is to provide a better understanding of acoustical properties of nonwovens, and to model the noise control behavior in terms of material and treatment parameters. A review of existing models on sound absorption of fibrous materials, coupled with experimental data will help in modeling sound absorption in multi-layer needle-punched nonwoven fabrics of different fibers: hemp, polylactide, polypropylene, and glassfiber. The effects of several treatments, which the materials may undergo during sound absorber manufacturing, namely alkalization, compression and heat treatments are investigated. The collected data is evaluated by experts. Expert evaluation further provides information about market demands for sound absorbers, and the perception of the designed nonwovens through the eyes of professionals. This research provides a contribution to the body of knowledge on the sound absorption properties of nonwovens, and provides a better understanding of the effects of some manufacturing processes on nonwovens' noise control performance and contributes to the wider adoption of nonwovens as sound absorbers.

  18. North Pacific Acoustic Laboratory and Deep Water Acoustics

    Science.gov (United States)

    2016-10-27

    Acoustic Lab and Deep Water Acoustics” Encl: (1) Final Technical Report for Subject Grant (2) SF298 for Enclosure Enclosure (1) is the Final...North Pacific Acoustic Laboratory and Deep Water Acoustics Final Report PI James A. Mercer Applied Physics Laboratory...During FY16 the primary effort has been working on manuscripts as summarized below: 1) A test of deep water Rytov theory at 284 Hz and 107 km in

  19. ACOUSTIC EMISSION ANALYZER

    Directory of Open Access Journals (Sweden)

    J. J. Almeida-Pérez

    2004-12-01

    Full Text Available In this paper appears a solution for acoustic emission analysis commonly known as noise. For the accomplishmentof this work a personal computer is used, besides sensors (microphones and boards designed and built for signalconditioning. These components are part of a virtual instrument used for monitoring the acoustical emission. Themain goal of this work is to develop a virtual instrument that supplies many important data as the result of ananalysis allowing to have information in an easy and friendly way. Moreover this information is very useful forstudying and resolving several situations in planning, production and testing areas.The main characteristics of the virtual instrument are: signal analysis in time, effective power measurement inDecibels (dB, average intensity taken from the principle of paired microphones, as well as the data analysis infrequency. These characteristics are included to handle two information channels.

  20. Acoustic absorption by sunspots

    Science.gov (United States)

    Braun, D. C.; Labonte, B. J.; Duvall, T. L., Jr.

    1987-01-01

    The paper presents the initial results of a series of observations designed to probe the nature of sunspots by detecting their influence on high-degree p-mode oscillations in the surrounding photosphere. The analysis decomposes the observed oscillations into radially propagating waves described by Hankel functions in a cylindrical coordinate system centered on the sunspot. From measurements of the differences in power between waves traveling outward and inward, it is demonstrated that sunspots appear to absorb as much as 50 percent of the incoming acoustic waves. It is found that for all three sunspots observed, the amount of absorption increases linearly with horizontal wavenumber. The effect is present in p-mode oscillations with wavelengths both significantly larger and smaller than the diameter of the sunspot umbrae. Actual absorption of acoustic energy of the magnitude observed may produce measurable decreases in the power and lifetimes of high-degree p-mode oscillations during periods of high solar activity.

  1. Electromagnetic acoustic imaging.

    Science.gov (United States)

    Emerson, Jane F; Chang, David B; McNaughton, Stuart; Jeong, Jong Seob; Shung, K K; Cerwin, Stephen A

    2013-02-01

    Electromagnetic acoustic imaging (EMAI) is a new imaging technique that uses long-wavelength RF electromagnetic (EM) waves to induce ultrasound emission. Signal intensity and image contrast have been found to depend on spatially varying electrical conductivity of the medium in addition to conventional acoustic properties. The resultant conductivity- weighted ultrasound data may enhance the diagnostic performance of medical ultrasound in cancer and cardiovascular applications because of the known changes in conductivity of malignancy and blood-filled spaces. EMAI has a potential advantage over other related imaging techniques because it combines the high resolution associated with ultrasound detection with the generation of the ultrasound signals directly related to physiologically important electrical properties of the tissues. Here, we report the theoretical development of EMAI, implementation of a dual-mode EMAI/ultrasound apparatus, and successful demonstrations of EMAI in various phantoms designed to establish feasibility of the approach for eventual medical applications.

  2. Radiosurgery of acoustic neurinomas

    Energy Technology Data Exchange (ETDEWEB)

    Flickinger, J.C.; Lunsford, L.D.; Coffey, R.J.; Linskey, M.E.; Bissonette, D.J.; Maitz, A.H.; Kondziolka, D. (Univ. of Pittsburgh School of Medicine, PA (USA))

    1991-01-15

    Eighty-five patients with acoustic neurinomas underwent stereotactic radiosurgery with the gamma unit at the University of Pittsburgh (Pittsburgh, PA) during its first 30 months of operation. Neuroimaging studies performed in 40 patients with more than 1 year follow-up showed that tumors were smaller in 22 (55%), unchanged in 17 (43%), and larger in one (2%). The 2-year actuarial rates for preservation of useful hearing and any hearing were 46% and 62%, respectively. Previously undetected neuropathies of the trigeminal (n = 12) and facial nerves (n = 14) occurred 1 week to 1 year after radiosurgery (median, 7 and 6 months, respectively), and improved at median intervals of 13 and 8 months, respectively, after onset. Hearing loss was significantly associated with increasing average tumor diameter (P = 0.04). No deterioration of any cranial nerve function has yet developed in seven patients with average tumor diameters less than 10 mm. Radiosurgery is an important treatment alternative for selected acoustic neurinoma patients.

  3. Deep Water Ocean Acoustics

    Science.gov (United States)

    2016-12-22

    deflection”, by Heaney and Campbell , was published in JASA in February of 2016. This paper introduces the Peregrine model to the community and...diffraction of basin-scale hydroacoustic signals”, by Heaney, Campbell and Mark Prior (TNO/CTBTO) describing observations and modeling of seismic events...signals” by Kevin D. Heaney, Richard L. Campbell and Mark Prior, and it was re- submitted to Journal of the Acoustical Society of America on August 30

  4. Acoustic Characterization of Soil

    Science.gov (United States)

    2007-11-02

    ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER Dept. of Electrical & Computer Enginnering Dept Natural Resources...same transduction device is used for transmit and receive, and the broad-band mechanical matching between the transduction device and the acoustic...has a direct influence over the imaging depth for a given dynamic range. Figure 10 demonstrated the influence of the roundtrip propagation loss as a

  5. Acoustic emission source modeling

    Directory of Open Access Journals (Sweden)

    Hora P.

    2010-07-01

    Full Text Available The paper deals with the acoustic emission (AE source modeling by means of FEM system COMSOL Multiphysics. The following types of sources are used: the spatially concentrated force and the double forces (dipole. The pulse excitation is studied in both cases. As a material is used steel. The computed displacements are compared with the exact analytical solution of point sources under consideration.

  6. Acoustic Communications for UUVs

    Science.gov (United States)

    2016-06-07

    through use of high-gain, error-control coding coupled with a modified decision feedback equalizer (DFE) which allows the gain to be exploited prior to...finished it wait for feedback from the receiver. At the host each packet is decoded and displayed if it is correct, or added to a list of bad packets if it...Systems Laboratory, Florida Alantic University, July 1998. L. Freitag el al: ‘A Bidriectional Coherent Acoustic Communications Systems for Underwater

  7. Latest Trends in Acoustic Sensing

    Directory of Open Access Journals (Sweden)

    Cinzia Caliendo

    2014-03-01

    Full Text Available Acoustics-based methods offer a powerful tool for sensing applications. Acoustic sensors can be applied in many fields ranging from materials characterization, structural health monitoring, acoustic imaging, defect characterization, etc., to name just a few. A proper selection of the acoustic wave frequency over a wide spectrum that extends from infrasound (<20 Hz up to ultrasound (in the GHz–band, together with a number of different propagating modes, including bulk longitudinal and shear waves, surface waves, plate modes, etc., allow acoustic tools to be successfully applied to the characterization of gaseous, solid and liquid environments. The purpose of this special issue is to provide an overview of the research trends in acoustic wave sensing through some cases that are representative of specific applications in different sensing fields.

  8. Fundamentals of Shallow Water Acoustics

    CERN Document Server

    Katsnelson, Boris; Lynch, James

    2012-01-01

    Shallow water acoustics (SWA), the study of how low and medium frequency sound propagates and scatters on the continental shelves of the world's oceans, has both technical interest and a large number of practical applications. Technically, shallow water poses an interesting medium for the study of acoustic scattering, inverse theory, and propagation physics in a complicated oceanic waveguide. Practically, shallow water acoustics has interest for geophysical exploration, marine mammal studies, and naval applications. Additionally, one notes the very interdisciplinary nature of shallow water acoustics, including acoustical physics, physical oceanography, marine geology, and marine biology. In this specialized volume, the authors, all of whom have extensive at-sea experience in U.S. and Russian research efforts, have tried to summarize the main experimental, theoretical, and computational results in shallow water acoustics, with an emphasis on providing physical insight into the topics presented.

  9. High-Frequency Seafloor Acoustics

    CERN Document Server

    Jackson, Darrell R

    2007-01-01

    High-Frequency Seafloor Acoustics is the first book in a new series sponsored by the Office of Naval Research on the latest research in underwater acoustics. This exciting new title provides ready access to experimental data, theory, and models relevant to high-frequency seafloor acoustics and will be of interest to sonar engineers and researchers working in underwater acoustics. The physical characteristics of the seafloor affecting acoustic propagation and scattering are covered, including physical and geoacoustic properties and surface roughness. Current theories for acoustic propagation in sediments are presented along with corresponding models for reflection, scattering, and seafloor penetration. The main text is backed up by an extensive bibliography and technical appendices.

  10. Wireless Acoustic Measurement System

    Science.gov (United States)

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

    2007-01-01

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

  11. Acoustic Imaging of Combustion Noise

    Science.gov (United States)

    Ramohalli, K. N.; Seshan, P. K.

    1984-01-01

    Elliposidal acoustic mirror used to measure sound emitted at discrete points in burning turbulent jets. Mirror deemphasizes sources close to target source and excludes sources far from target. At acoustic frequency of 20 kHz, mirror resolves sound from region 1.25 cm wide. Currently used by NASA for research on jet flames. Produces clearly identifiable and measurable variation of acoustic spectral intensities along length of flame. Utilized in variety of monitoring or control systems involving flames or other reacting flows.

  12. Spacecraft Internal Acoustic Environment Modeling

    Science.gov (United States)

    Chu, S. Reynold; Allen, Chris

    2009-01-01

    The objective of the project is to develop an acoustic modeling capability, based on commercial off-the-shelf software, to be used as a tool for oversight of the future manned Constellation vehicles. The use of such a model will help ensure compliance with acoustic requirements. Also, this project includes modeling validation and development feedback via building physical mockups and conducting acoustic measurements to compare with the predictions.

  13. Numerical investigation of natural convection heat transfer in a cylindrical enclosure due to ultrasonic vibrations.

    Science.gov (United States)

    Talebi, Maryam; Setareh, Milad; Saffar-Avval, Majid; Hosseini Abardeh, Reza

    2017-04-01

    Application of ultrasonic waves for heat transfer augmentation has been proposed in the last few decades. Due to limited researches on acoustic streaming induced by ultrasonic oscillation, the effect of ultrasonic waves on natural convection heat transfer is the main purpose of this paper. At first, natural convection on up-ward-facing heating surface in a cylindrical enclosure filled with air is investigated numerically by the finite difference method, then the effect of upper surface oscillation on convection heat transfer is considered. The conservation equations in Lagrangian approach and compressible fluid are assumed for the numerical simulation. Results show that acoustic pressure will become steady after some milliseconds also pressure oscillation amplitude and acoustic velocity components will be constant therefore steady state velocity is used for solving energy equation. Results show that Enhancement of heat transfer coefficient can be up to 175% by induced ultrasonic waves. In addition, the effect of different parameters on acoustic streaming and heat transfer has been studied.

  14. Acoustic Communications Measurement Systems (ACOMMS)

    Data.gov (United States)

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

  15. NDE Acoustic Microscopy Research Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The purpose is to develop advanced, more effective high-resolution micro-NDE materials characterization methods using scanning acoustic microscopy. The laboratory's...

  16. Combined Environment Acoustic Chamber (CEAC)

    Data.gov (United States)

    Federal Laboratory Consortium — Purpose: The CEAC imposes combined acoustic, thermal and mechanical loads on aerospace structures. The CEAC is employed to measure structural response and determine...

  17. Predicting Acoustics in Class Rooms

    DEFF Research Database (Denmark)

    Christensen, Claus Lynge; Rindel, Jens Holger

    2005-01-01

    Typical class rooms have fairly simple geometries, even so room acoustics in this type of room is difficult to predict using today's room acoustic computer modeling software. The reasons why acoustics of class rooms are harder to predict than acoustics of complicated concert halls might...... coefficients that are used in order to describe surface scattering (roughness of material) as well as scattering of reflected sound caused by limited surface size (diffraction). A method which combines scattering caused by diffraction due to surface dimensions, angle of incidence and incident path length...

  18. A one-dimensional heat transfer model for parallel-plate thermoacoustic heat exchangers.

    Science.gov (United States)

    de Jong, J A; Wijnant, Y H; de Boer, A

    2014-03-01

    A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic systems. The model is implementable in existing (quasi-)1D thermoacoustic codes, such as DeltaEC. Examples of generated results show good agreement with literature results. The model allows for arbitrary wave phasing; however, it is shown that the wave phasing does not significantly influence the heat transfer.

  19. Analytical and numerical calculations of optimum design frequency for focused ultrasound therapy and acoustic radiation force.

    Science.gov (United States)

    Ergün, A Sanlı

    2011-10-01

    Focused ultrasound therapy relies on acoustic power absorption by tissue. The stronger the absorption the higher the temperature increase is. However, strong acoustic absorption also means faster attenuation and limited penetration depth. Hence, there is a trade-off between heat generation efficacy and penetration depth. In this paper, we formulated the acoustic power absorption as a function of frequency and attenuation coefficient, and defined two figures of merit to measure the power absorption: spatial peak of the acoustic power absorption density, and the acoustic power absorbed within the focal area. Then, we derived "rule of thumb" expressions for the optimum frequencies that maximized these figures of merit given the target depth and homogeneous tissue type. We also formulated a method to calculate the optimum frequency for inhomogeneous tissue given the tissue composition for situations where the tissue structure can be assumed to be made of parallel layers of homogeneous tissue. We checked the validity of the rules using linear acoustic field simulations. For a one-dimensional array of 4cm acoustic aperture, and for a two-dimensional array of 4×4cm(2) acoustic aperture, we found that the power absorbed within the focal area is maximized at 0.86MHz, and 0.79MHz, respectively, when the target depth is 4cm in muscle tissue. The rules on the other hand predicted the optimum frequencies for acoustic power absorption as 0.9MHz and 0.86MHz, respectively for the 1D and 2D array case, which are within 6% and 9% of the field simulation results. Because radiation force generated by an acoustic wave in a lossy propagation medium is approximately proportional to the acoustic power absorption, these rules can be used to maximize acoustic radiation force generated in tissue as well.

  20. Heat Stress

    Science.gov (United States)

    ... Publications and Products Programs Contact NIOSH NIOSH HEAT STRESS Recommend on Facebook Tweet Share Compartir NEW OSHA- ... hot environments may be at risk of heat stress. Exposure to extreme heat can result in occupational ...

  1. Heating automation

    OpenAIRE

    Tomažič, Tomaž

    2013-01-01

    This degree paper presents usage and operation of peripheral devices with microcontroller for heating automation. The main goal is to make a quality system control for heating three house floors and with that, increase efficiency of heating devices and lower heating expenses. Heat pump, furnace, boiler pump, two floor-heating pumps and two radiator pumps need to be controlled by this system. For work, we have chosen a development kit stm32f4 - discovery with five temperature sensors, LCD disp...

  2. Change of nonlinear acoustics in ASME grade 122 steel welded joint during creep

    Science.gov (United States)

    Ohtani, Toshihiro; Honma, Takumi; Ishii, Yutaka; Tabuchi, Masaaki; Hongo, Hiromichi; Hirao, Masahiko

    2016-02-01

    In this paper, we described the changes of two nonlinear acoustic characterizations; resonant frequency shift and three-wave interaction, with electromagnetic acoustic resonance (EMAR) throughout the creep life in the welded joints of ASME Grade 122, one of high Cr ferritic heat resisting steels. EMAR was a combination of the resonant acoustic technique with a non-contact electromagnetic acoustic transducer (EMAT). These nonlinear acoustic parameters decreased from the start to 50% of creep life. After slightly increased, they rapidly increased from 80% of creep life to rupture. We interpreted these phenomena in terms of dislocation recovery, recrystallization, and restructuring related to the initiation and growth of creep void, with support from the SEM and TEM observation.

  3. Acoustic transparency and slow sound using detuned acoustic resonators

    DEFF Research Database (Denmark)

    Santillan, Arturo Orozco; Bozhevolnyi, Sergey I.

    2011-01-01

    We demonstrate that the phenomenon of acoustic transparency and slowsound propagation can be realized with detuned acoustic resonators (DAR), mimicking thereby the effect of electromagnetically induced transparency (EIT) in atomic physics. Sound propagation in a pipe with a series of side...

  4. Naturally enhanced ion-acoustic lines at high altitudes

    Directory of Open Access Journals (Sweden)

    Y. Ogawa

    2006-12-01

    Full Text Available Naturally enhanced ion-acoustic lines (NEIALs between 1200 and 1900 km altitude are investigated. The NEIALs were found in the background gates of data from the European Incoherent Scatter (EISCAT Svalbard radar (ESR at 78° N looking field-aligned. Only strongly enhanced lines are detected at such high altitudes. The estimated enhancement above incoherent scattering integrated over the antenna beam and preintegration time of 10 s reaches about 10 000. Both lines are always enhanced above 1000 km altitude, and the downshifted line, corresponding to upward propagating ion-acoustic waves, is always stronger than the upshifted line, for downgoing waves. The ratio of the downshifted and upshifted peaks is often remarkably constant along a profile. Using the line positions as indicators of the ion-acoustic speeds and the bulk drift velocity, we find that the bulk drift does not exceed the ion-acoustic (sound speed, but extrapolation of the profiles suggests that the sound barrier is reached around 2000 km in one event. The highest ion-acoustic speed is seen near 600 km, above the density peak, indicating that electrons are heated not only by ionizing precipitation but significantly also by upgoing waves. Upflow continues to speed up above the estimated temperature maximum. A certain qualitative similarity to the solar corona seems to be the case.

  5. Calibration of acoustic sensors in ice using the reciprocity method

    Energy Technology Data Exchange (ETDEWEB)

    Meures, Thomas; Bissok, Martin; Laihem, Karim; Paul, Larissa; Wiebusch, Christopher; Zierke, Simon [III. Physikalisches Institut, RWTH Aachen (Germany); Semburg, Benjamin [Bergische Universitaet Wuppertal (Germany). Fachbereich C

    2010-07-01

    Within the IceCube experiment at the South Pole an R and D program investigates new ways of ultra high energy neutrino detection. In particular when aiming for detector volumes of the order of 100 km{sup 3} acoustic or radio detectors are promising approaches. The acoustic detection method relies on the thermo-acoustic effect occurring when high energetic particles interact and deposit heat within a detection medium. This effect is investigated in the Aachen Acoustic Laboratory (AAL). The high energy particle interaction is simulated by a powerful pulsed Nd:YAG LASER shooting into a 3m{sup 3} tank of clear ice (or water). Eighteen acoustic sensors are situated on three rings in different depths and record the generated signals. These sensors serve as reference for later measurements of other devices. The reciprocity method, used for the absolute calibration of these sensors, is independent of an absolutely calibrated reference. This method and its application to the calibration of the AAL sensors are presented and first results are shown.

  6. Acoustic Mechanical Feedthroughs

    Science.gov (United States)

    Sherrit, Stewart; Walkemeyer, Phillip; Bao, Xiaoqi; Bar-Cohen, Yoseph; Badescu, Mircea

    2013-01-01

    Electromagnetic motors can have problems when operating in extreme environments. In addition, if one needs to do mechanical work outside a structure, electrical feedthroughs are required to transport the electric power to drive the motor. In this paper, we present designs for driving rotary and linear motors by pumping stress waves across a structure or barrier. We accomplish this by designing a piezoelectric actuator on one side of the structure and a resonance structure that is matched to the piezoelectric resonance of the actuator on the other side. Typically, piezoelectric motors can be designed with high torques and lower speeds without the need for gears. One can also use other actuation materials such as electrostrictive, or magnetostrictive materials in a benign environment and transmit the power in acoustic form as a stress wave and actuate mechanisms that are external to the benign environment. This technology removes the need to perforate a structure and allows work to be done directly on the other side of a structure without the use of electrical feedthroughs, which can weaken the structure, pipe, or vessel. Acoustic energy is pumped as a stress wave at a set frequency or range of frequencies to produce rotary or linear motion in a structure. This method of transferring useful mechanical work across solid barriers by pumping acoustic energy through a resonant structure features the ability to transfer work (rotary or linear motion) across pressure or thermal barriers, or in a sterile environment, without generating contaminants. Reflectors in the wall of barriers can be designed to enhance the efficiency of the energy/power transmission. The method features the ability to produce a bi-directional driving mechanism using higher-mode resonances. There are a variety of applications where the presence of a motor is complicated by thermal or chemical environments that would be hostile to the motor components and reduce life and, in some instances, not be

  7. Frequency steerable acoustic transducers

    Science.gov (United States)

    Senesi, Matteo

    Structural health monitoring (SHM) is an active research area devoted to the assessment of the structural integrity of critical components of aerospace, civil and mechanical systems. Guided wave methods have been proposed for SHM of plate-like structures using permanently attached piezoelectric transducers, which generate and sense waves to evaluate the presence of damage. Effective interrogation of structural health is often facilitated by sensors and actuators with the ability to perform electronic, i.e. phased array, scanning. The objective of this research is to design an innovative directional piezoelectric transducer to be employed for the localization of broadband acoustic events, or for the generation of Lamb waves for active interrogation of structural health. The proposed Frequency Steerable Acoustic Transducers (FSATs) are characterized by a spatial arrangement of active material which leads to directional characteristics varying with frequency. Thus FSATs can be employed both for directional sensing and generation of guided waves without relying on phasing and control of a large number of channels. The analytical expression of the shape of the FSATs is obtained through a theoretical formulation for continuously distributed active material as part of a shaped piezoelectric device. The FSAT configurations analyzed in this work are a quadrilateral array and a geometry which corresponds to a spiral in the wavenumber domain. The quadrilateral array is experimentally validated, confirming the concept of frequency-dependent directionality. Its limited directivity is improved by the Wavenumber Spiral FSAT (WS-FSAT), which, instead, is characterized by a continuous frequency dependent directionality. Preliminary validations of the WS-FSAT, using a laser doppler vibrometer, are followed by the implementation of the WS-FSAT as a properly shaped piezo transducer. The prototype is first used for localization of acoustic broadband sources. Signal processing

  8. Wind turbine acoustics

    Science.gov (United States)

    Hubbard, Harvey H.; Shepherd, Kevin P.

    1990-01-01

    Available information on the physical characteristics of the noise generated by wind turbines is summarized, with example sound pressure time histories, narrow- and broadband frequency spectra, and noise radiation patterns. Reviewed are noise measurement standards, analysis technology, and a method of characterizing wind turbine noise. Prediction methods are given for both low-frequency rotational harmonics and broadband noise components. Also included are atmospheric propagation data showing the effects of distance and refraction by wind shear. Human perception thresholds, based on laboratory and field tests, are given. Building vibration analysis methods are summarized. The bibliography of this report lists technical publications on all aspects of wind turbine acoustics.

  9. Wind turbine acoustics

    Science.gov (United States)

    Hubbard, Harvey H.; Shepherd, Kevin P.

    1990-12-01

    Available information on the physical characteristics of the noise generated by wind turbines is summarized, with example sound pressure time histories, narrow- and broadband frequency spectra, and noise radiation patterns. Reviewed are noise measurement standards, analysis technology, and a method of characterizing wind turbine noise. Prediction methods are given for both low-frequency rotational harmonics and broadband noise components. Also included are atmospheric propagation data showing the effects of distance and refraction by wind shear. Human perception thresholds, based on laboratory and field tests, are given. Building vibration analysis methods are summarized. The bibliography of this report lists technical publications on all aspects of wind turbine acoustics.

  10. Taming Acoustic Cavitation

    CERN Document Server

    Rivas, David Fernandez; Enriquez, Oscar R; Versluis, Michel; Prosperetti, Andrea; Gardeniers, Han; Lohse, Detlef

    2012-01-01

    In this fluid dynamics video we show acoustic cavitation occurring from pits etched on a silicon surface. By immersing the surface in a liquid, gas pockets are entrapped in the pits which upon ultrasonic insonation, are observed to shed cavitation bubbles. Modulating the driving pressure it is possible to induce different behaviours based on the force balance that determines the interaction among bubbles and the silicon surface. This system can be used for several applications like sonochemical water treatment, cleaning of surfaces with deposited materials such as biofilms.

  11. Anomalous absorption of laser light on ion acoustic fluctuations

    Science.gov (United States)

    Rozmus, Wojciech; Bychenkov, Valery Yu.

    2016-10-01

    Theory of laser light absorption due to ion acoustic turbulence (IAT) is discussed in high Z plasmas where ion acoustic waves are weakly damped. Our theory applies to the whole density range from underdense to critical density plasmas. It includes an absorption rate for the resonance anomalous absorption due to linear conversion of electromagnetic waves into electron plasma oscillations by the IAT near the critical density in addition to the absorption coefficient due to enhanced effective electron collisionality. IAT is driven by large electron heat flux through the return current instability. Stationary spectra of IAT are given by weak plasma turbulence theory and applied in description of the anomalous absorption in the inertial confinement fusion plasmas at the gold walls of a hohlraum. This absorption is anisotropic in nature due to IAT angular anisotropy and differs for p- and s-polarization of the laser radiation. Possible experiments which could identify the resonance anomalous absorption in a laser heated plasma are discussed.

  12. Low-temperature heat transfer in nanowires

    OpenAIRE

    Glavin, B. A.

    2000-01-01

    The new regime of low-temperature heat transfer in suspended nanowires is predicted. It takes place when (i) only ``acoustic'' phonon modes of the wire are thermally populated and (ii) phonons are subject to the effective elastic scattering. Qualitatively, the main peculiarities of heat transfer originate due to appearance of the flexural modes with high density of states in the wire phonon spectrum. They give rise to the $T^{1/2}$ temperature dependence of the wire thermal conductance. The e...

  13. Acoustic Center or Time Origin?

    DEFF Research Database (Denmark)

    Staffeldt, Henrik

    1999-01-01

    The paper discusses the acoustic center in relation to measurements of loudspeaker polar data. Also, it presents the related concept time origin and discusses the deviation that appears between positions of the acoustic center found by wavefront based and time based measuring methods....

  14. Propagation of Ion Acoustic Perturbations

    DEFF Research Database (Denmark)

    Pécseli, Hans

    1975-01-01

    Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered.......Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered....

  15. Acoustic Ground-Impedance Meter

    Science.gov (United States)

    Zuckerwar, A. J.

    1983-01-01

    Helmoltz resonator used in compact, portable meter measures acoustic impedance of ground or other surfaces. Earth's surface is subject of increasing acoustical investigations because of its importance in aircraft noise prediction and measurment. Meter offers several advantages. Is compact and portable and set up at any test site, irrespective of landscape features, weather or other environmental condition.

  16. Combining Passive Thermography and Acoustic Emission for Large Area Fatigue Damage Growth Assessment of a Composite Structure

    Science.gov (United States)

    Zalameda, Joseph N.; Horne, Michael R.; Madaras, Eric I.; Burke, Eric R.

    2016-01-01

    Passive thermography and acoustic emission data were obtained for improved real time damage detection during fatigue loading. A strong positive correlation was demonstrated between acoustic energy event location and thermal heating, especially if the structure under load was nearing ultimate failure. An image processing routine was developed to map the acoustic emission data onto the thermal imagery. This required removing optical barrel distortion and angular rotation from the thermal data. The acoustic emission data were then mapped onto thermal data, revealing the cluster of acoustic emission event locations around the thermal signatures of interest. By combining both techniques, progression of damage growth is confirmed and areas of failure are identified. This technology provides improved real time inspections of advanced composite structures during fatigue testing.Keywords: Thermal nondestructive evaluation, fatigue damage detection, aerospace composite inspection, acoustic emission, passive thermography

  17. Heat pumps

    CERN Document Server

    Macmichael, DBA

    1988-01-01

    A fully revised and extended account of the design, manufacture and use of heat pumps in both industrial and domestic applications. Topics covered include a detailed description of the various heat pump cycles, the components of a heat pump system - drive, compressor, heat exchangers etc., and the more practical considerations to be taken into account in their selection.

  18. Two Heat-Transfer Improvements for Gas Liquefiers

    Science.gov (United States)

    Martin, Jerry L.

    2005-01-01

    Two improvements in heat-transfer design have been investigated with a view toward increasing the efficiency of refrigerators used to liquefy gases. The improvements could contribute to the development of relatively inexpensive, portable oxygen liquefiers for medical use. A description of the heat-transfer problem in a pulse-tube refrigerator is prerequisite to a meaningful description of the first improvement. In a pulse-tube refrigerator in particular, one of in-line configuration heat must be rejected from two locations: an aftercooler (where most of the heat is rejected) and a warm heat exchanger (where a small fraction of the total input power must be rejected as heat). Rejection of heat from the warm heat exchanger can be problematic because this heat exchanger is usually inside a vacuum vessel. When an acoustic-inertance tube is used to provide a phase shift needed in the pulse-tube cooling cycle, another problem arises: Inasmuch as the acoustic power in the acoustic-inertance tube is dissipated over the entire length of the tube, the gas in the tube must be warmer than the warm heat exchanger in order to reject heat at the warm heat exchanger. This is disadvantageous because the increase in viscosity with temperature causes an undesired increase in dissipation of acoustic energy and an undesired decrease in the achievable phase shift. Consequently, the overall performance of the pulse-tube refrigerator decreases with increasing temperature in the acoustic-inertance tube. In the first improvement, the acoustic-inertance tube is made to serve as the warm heat exchanger and to operate in an approximately isothermal condition at a lower temperature, thereby increasing the achievable phase shift and the overall performance of the refrigerator. This is accomplished by placing the acoustic-inertance tube inside another tube and pumping a cooling fluid (e.g., water) in the annular space between the tubes. Another benefit of this improvement is added flexibility of

  19. Acoustic emission linear pulse holography

    Science.gov (United States)

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

    1983-10-25

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

  20. Acoustic Absorption in Porous Materials

    Science.gov (United States)

    Kuczmarski, Maria A.; Johnston, James C.

    2011-01-01

    An understanding of both the areas of materials science and acoustics is necessary to successfully develop materials for acoustic absorption applications. This paper presents the basic knowledge and approaches for determining the acoustic performance of porous materials in a manner that will help materials researchers new to this area gain the understanding and skills necessary to make meaningful contributions to this field of study. Beginning with the basics and making as few assumptions as possible, this paper reviews relevant topics in the acoustic performance of porous materials, which are often used to make acoustic bulk absorbers, moving from the physics of sound wave interactions with porous materials to measurement techniques for flow resistivity, characteristic impedance, and wavenumber.

  1. Wastewater treatment with acoustic separator

    Science.gov (United States)

    Kambayashi, Takuya; Saeki, Tomonori; Buchanan, Ian

    2017-07-01

    Acoustic separation is a filter-free wastewater treatment method based on the forces generated in ultrasonic standing waves. In this report, a batch-system separator based on acoustic separation was demonstrated using a small-scale prototype acoustic separator to remove suspended solids from oil sand process-affected water (OSPW). By applying an acoustic separator to the batch use OSPW treatment, the required settling time, which was the time that the chemical oxygen demand (COD) decreased to the environmental criterion (<200 mg/L), could be shortened from 10 to 1 min. Moreover, for a 10 min settling time, the acoustic separator could reduce the FeCl3 dose as coagulant in OSPW treatment from 500 to 160 mg/L.

  2. External Acoustic Liners for Multi-Functional Aircraft Noise Reduction

    Science.gov (United States)

    Jones, Michael G. (Inventor); Thomas, Russell H. (Inventor); Nark, Douglas M. (Inventor); Howerton, Brian M. (Inventor); Czech, Michael J. (Inventor)

    2017-01-01

    Acoustic liners for aircraft noise reduction include one or more chambers that are configured to provide a pressure-release surface such that the engine noise generation process is inhibited and/or absorb sound by converting the sound into heat energy. The size and shape of the chambers can be selected to inhibit the noise generation process and/or absorb sound at selected frequencies.

  3. Lamb's Hydrostatic Adjustment for Heating of Finite Duration.

    Science.gov (United States)

    Sotack, Timothy; Bannon, Peter R.

    1999-01-01

    Lamb's hydrostatic adjustment problem for the linear response of an infinite, isothermal atmosphere to an instantaneous heating of infinite horizontal extent is generalized to include the effects of heating of finite duration. Three different time sequences of the heating are considered: a top hat, a sine, and a sine-squared heating. The transient solution indicates that heating of finite duration generates broader but weaker acoustic wave fronts. However, it is shown that the final equilibrium is the same regardless of the heating sequence provided the net heating is the same.A Lagrangian formulation provides a simple interpretation of the adjustment. The heating generates an entropy anomaly that is initially realized completely as a pressure excess with no density perturbation. In the final state the entropy anomaly is realized as a density deficit with no pressure perturbation. Energetically the heating generates both available potential energy and available elastic energy. The former remains in the heated layer while the latter is carried off by the acoustic waves.The wave energy generation is compared for the various heating sequences. In the instantaneous case, 28.6% of the total energy generation is carried off by waves. This fraction is the ratio of the ideal gas constant R to the specific heat at constant pressure cp. For the heatings of finite duration considered, the amount of wave energy decreases monotonically as the heating duration increases and as the heating thickness decreases. The wave energy generation approaches zero when (i) the duration of the heating is comparable to or larger than the acoustic cutoff period, 2/NA 300 s, and (ii) the thickness of the heated layer approaches zero. The maximum wave energy occurs for a thick layer of heating of small duration and is the same as that for the instantaneous case.The effect of a lower boundary is also considered.

  4. Acoustics and Hearing

    CERN Document Server

    Damaske, Peter

    2008-01-01

    When one listens to music at home, one would like to have an acoustic impression close to that of being in the concert hall. Until recently this meant elaborate multi-channelled sound systems with 5 or more speakers. But head-related stereophony achieves the surround-sound effect in living rooms with only two loudspeakers. By virtue of their slight directivity as well as an electronic filter the limitations previously common to two-speaker systems can be overcome and this holds for any arbitrary two-channel recording. The book also investigates the question of how a wide and diffuse sound image can arise in concert halls and shows that the quality of concert halls decisively depends on diffuse sound images arising in the onset of reverberation. For this purpose a strong onset of reverberation is modified in an anechoic chamber by electroacoustic means. Acoustics and Hearing proposes ideas concerning signal processing in the auditory system that explain the measured results and the resultant sound effects plea...

  5. Acoustic data transmission method

    Energy Technology Data Exchange (ETDEWEB)

    Duckworth, A.

    1991-09-17

    This patent describes a method for transmitting time line data through a drillstring having drill pipe sections connected end-to-end by joints from a first location below the surface of the earth to a second location at or near the surface of the earth, the length and cross-sectional area of the drill pipe sections being different from the length and cross-sectional area of the joints. It comprises generating acoustic data signals having a single frequency content in at least one passband of the drillstring; transmitting the data signals through the drillstring from either the first location to the second location or from the second location to the first location during a time period prior to the onset of reflective interference caused by the data signals reflecting from along the length of the drillstring, the time period being equal to or less than the time for the data signals to travel three lengths of the drillstring; stopping the transmission of data signals at the onset of the reflective interference and allowing the acoustic signals to substantially attenuate; and detecting the data signals at the respective first or second location.

  6. [Acoustical parameters of toys].

    Science.gov (United States)

    Harazin, Barbara

    2010-01-01

    Toys play an important role in the development of the sight and hearing concentration in children. They also support the development of manipulation, gently influence a child and excite its emotional activities. A lot of toys emit various sounds. The aim of the study was to assess sound levels produced by sound-emitting toys used by young children. Acoustical parameters of noise were evaluated for 16 sound-emitting plastic toys in laboratory conditions. The noise level was recorded at four different distances, 10, 20, 25 and 30 cm, from the toy. Measurements of A-weighted sound pressure levels and noise levels in octave band in the frequency range from 31.5 Hz to 16 kHz were performed at each distance. Taking into consideration the highest equivalent A-weighted sound levels produced by tested toys, they can be divided into four groups: below 70 dB (6 toys), from 70 to 74 dB (4 toys), from 75 to 84 dB (3 toys) and from 85 to 94 dB (3 toys). The majority of toys (81%) emitted dominant sound levels in octave band at the frequency range from 2 kHz to 4 kHz. Sound-emitting toys produce the highest acoustic energy at the frequency range of the highest susceptibility of the auditory system. Noise levels produced by some toys can be dangerous to children's hearing.

  7. Evoked acoustic emission

    DEFF Research Database (Denmark)

    Elberling, C; Parbo, J; Johnsen, N J

    1985-01-01

    Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has onl...... reveals presence of a true emission from all ears tested. It is concluded that the cochlear echo can be recorded in normal-hearing newborns with an extremely low rate of type I errors.......Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has only...... a minor effect on the power spectra, i.e. the maximum jumps from one spectral peak to another. Experiments with deconvolution demonstrate that the emission generating system at least at a fixed intensity can be regarded as being linear and characterized by its impulse response which is similar...

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

    Science.gov (United States)

    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

  9. Acoustic detection of high energy neutrinos in sea water: status and prospects

    Directory of Open Access Journals (Sweden)

    Lahmann Robert

    2017-01-01

    Full Text Available The acoustic neutrino detection technique is a promising approach for future large-scale detectors with the aim of measuring the small expected flux of neutrinos at energies in the EeV-range and above. The technique is based on the thermo-acoustic model, which implies that the energy deposition by a particle cascade – resulting from a neutrino interaction in a medium with suitable thermal and acoustic properties – leads to a local heating and a subsequent characteristic pressure pulse that propagates in the surrounding medium. Current or recent test setups for acoustic neutrino detection have either been add-ons to optical neutrino telescopes or have been using acoustic arrays built for other purposes, typically for military use. While these arrays have been too small to derive competitive limits on neutrino fluxes, they allowed for detailed studies of the experimental technique. With the advent of the research infrastructure KM3NeT in the Mediterranean Sea, new possibilities will arise for acoustic neutrino detection. In this article, results from the “first generation” of acoustic arrays will be summarized and implications for the future of acoustic neutrino detection will be discussed.

  10. Acoustic detection of high energy neutrinos in sea water: status and prospects

    Science.gov (United States)

    Lahmann, Robert

    2017-03-01

    The acoustic neutrino detection technique is a promising approach for future large-scale detectors with the aim of measuring the small expected flux of neutrinos at energies in the EeV-range and above. The technique is based on the thermo-acoustic model, which implies that the energy deposition by a particle cascade - resulting from a neutrino interaction in a medium with suitable thermal and acoustic properties - leads to a local heating and a subsequent characteristic pressure pulse that propagates in the surrounding medium. Current or recent test setups for acoustic neutrino detection have either been add-ons to optical neutrino telescopes or have been using acoustic arrays built for other purposes, typically for military use. While these arrays have been too small to derive competitive limits on neutrino fluxes, they allowed for detailed studies of the experimental technique. With the advent of the research infrastructure KM3NeT in the Mediterranean Sea, new possibilities will arise for acoustic neutrino detection. In this article, results from the "first generation" of acoustic arrays will be summarized and implications for the future of acoustic neutrino detection will be discussed.

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

    Science.gov (United States)

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

    1998-11-01

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

  12. Heat pumps

    CERN Document Server

    Brodowicz, Kazimierz; Wyszynski, M L; Wyszynski

    2013-01-01

    Heat pumps and related technology are in widespread use in industrial processes and installations. This book presents a unified, comprehensive and systematic treatment of the design and operation of both compression and sorption heat pumps. Heat pump thermodynamics, the choice of working fluid and the characteristics of low temperature heat sources and their application to heat pumps are covered in detail.Economic aspects are discussed and the extensive use of the exergy concept in evaluating performance of heat pumps is a unique feature of the book. The thermodynamic and chemical properties o

  13. Effect of acoustic streaming on the mass transfer from a sublimating sphere

    Science.gov (United States)

    Kawahara, N.; Yarin, A. L.; Brenn, G.; Kastner, O.; Durst, F.

    2000-04-01

    The effect of the acoustic streaming on the mass transfer from the surface of a sphere positioned in an ultrasonic acoustic levitator is studied both experimentally and theoretically. Acoustic levitation using standing ultrasonic waves is an experimental tool for studying the heat and mass transfer from small solid or liquid samples, because it allows an almost steady positioning of a sample at a fixed location in space. However, the levitator introduces some difficulties. One of the main problems with acoustic levitation is that an acoustic streaming is induced near the sample surface, which affects the heat and mass transfer rates, as characterized by increased Nusselt and Sherwood numbers. The transfer rates are not uniform along the sample surface, and the aim of the present study is to quantify the spatial Sherwood number distribution over the surface of a sphere. The experiments are based on the measurement of the surface shape of a sphere layered with a solid substance as a function of time using a charge-coupled device (CCD) camera with backlighting. The sphere used in this research is a glass sphere layered with a volatile solid substance (naphthalene or camphor). The local mass transfer from the surface both with and without an ultrasonic acoustic field is investigated in order to evaluate the effect of the acoustic streaming. The experimental results are compared with predictions following from the theory outlined [A. L. Yarin, M. Pfaffenlehner, and C. Tropea, J. Fluid Mech. 356, 65 (1998); A. L. Yarin, G. Brenn, O. Kastner, D. Rensink, and C. Tropea, ibid. 399, 151 (1999)] which describes the acoustic field and the resulting acoustic streaming, and the mass transfer at the surface of particles and droplets located in an acoustic levitator. The results are also compared with the experimental data and with the theoretical predictions of Burdukov and Nakoryakov [J. Appl. Mech. Tech. Phys. 6, 51 (1965)], which are valid only in the case of spherical

  14. Surface Acoustic Wave Devices

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    of a Mach-Zehnder interferometer (MZI). This is an optical device consisting if one waveguide that is split into two waveguide arms which are assembled again later on. By applying the mechanical field from a SAW the light in the two arms can be modulated and interfere constructively and destructively......The work of this project is concerned with the simulation of surface acoustic waves (SAW) and topology optimization of SAW devices. SAWs are elastic vibrations that propagate along a material surface and are extensively used in electromechanical filters and resonators in telecommunication. A new...... application is modulation of optical waves in waveguides. This presentation elaborates on how a SAW is generated by interdigital transducers using a 2D model of a piezoelectric, inhomogeneous material implemented in the high-level programming language Comsol Multiphysics. The SAW is send through a model...

  15. Acoustic cavitation movies

    Science.gov (United States)

    Crum, Lawrence A.

    2003-04-01

    Acoustic cavitation is a phenomenon that occurs on microsecond time scales and micron length scales, yet, it has many macroscopic manifestations. Accordingly, it is often difficult, at least for the author, to form realistic physical descriptions of the specific mechanisms through which it expresses itself in our macroscopic world. For example, there are still many who believe that cavitation erosion is due to the shock wave that is emitted by bubble implosion, rather than the liquid jet created on asymmetric collapse...and they may be right. Over the years, the author has accumulated a number of movies and high-speed photographs of cavitation activity, which he uses to form his own visual references. In the time allotted, he will show a number of these movies and photographs and discuss their relevance to existing technological problems. A limited number of CDs containing the presented materials will be available to interested individuals. [Work supported in part by the NIH, USAMRMC, and the ONR.

  16. Acoustic classification of dwellings

    DEFF Research Database (Denmark)

    Berardi, Umberto; Rasmussen, Birgit

    2014-01-01

    Schemes for the classification of dwellings according to different building performances have been proposed in the last years worldwide. The general idea behind these schemes relates to the positive impact a higher label, and thus a better performance, should have. In particular, focusing on soun...... exchanging experiences about constructions fulfilling different classes, reducing trade barriers, and finally increasing the sound insulation of dwellings.......Schemes for the classification of dwellings according to different building performances have been proposed in the last years worldwide. The general idea behind these schemes relates to the positive impact a higher label, and thus a better performance, should have. In particular, focusing on sound...... insulation performance, national schemes for sound classification of dwellings have been developed in several European countries. These schemes define acoustic classes according to different levels of sound insulation. Due to the lack of coordination among countries, a significant diversity in terms...

  17. Electromagnetic acoustic transducer

    Science.gov (United States)

    Alers, George A.; Burns, Jr., Leigh R.; MacLauchlan, Daniel T.

    1988-01-01

    A noncontact ultrasonic transducer for studying the acoustic properties of a metal workpiece includes a generally planar magnetizing coil positioned above the surface of the workpiece, and a generally planar eddy current coil between the magnetizing coil and the workpiece. When a large current is passed through the magnetizing coil, a large magnetic field is applied to the near-surface regions of the workpiece. The eddy current coil can then be operated as a transmitter by passing an alternating current therethrough to excite ultrasonic waves in the surface of the workpiece, or operated as a passive receiver to sense ultrasonic waves in the surface by measuring the output signal. The geometries of the two coils can be varied widely to be effective for different types of ultrasonic waves. The coils are preferably packaged in a housing which does not interfere with their operation, but protects them from a variety of adverse environmental conditions.

  18. Acoustic/Magnetic Stress Sensor

    Science.gov (United States)

    Heyman, J. S.; Namkung, M.

    1986-01-01

    High-resolution sensor fast, portable, does not require permanent bonding to structure. Sensor measures nondestructively type (compressive or tensile) and magnitude of stresses and stress gradients present in class of materials. Includes precise high-resolution acoustic interferometer, sending acoustic transducer, receiving acoustic transducer, electromagnet coil and core, power supply, and magnetic-field-measuring device such as Hall probe. This measurement especially important for construction and applications where steel is widely used. Sensor useful especially for nondestructive evaluation of stress in steel members because of portability, rapid testing, and nonpermanent installation.

  19. Electro-acoustic stimulation. Acoustic and electric pitch comparisons

    National Research Council Canada - National Science Library

    McDermott, Hugh; Sucher, Catherine; Simpson, Andrea

    2009-01-01

    ... who had usable low-frequency hearing, either in the non-implanted ear or in both ears. The subjects assigned numerical pitch estimates to each of 5 acoustic pure tones and 5 single-electrode electric pulse trains...

  20. A synchronized particle image velocimetry and infrared thermography technique applied to an acoustic streaming flow

    Energy Technology Data Exchange (ETDEWEB)

    Sou, In Mei; Ray, Chittaranjan [University of Hawaii at Manoa, Department of Civil and Environmental Engineering, Honolulu, HI (United States); Allen, John S.; Layman, Christopher N. [University of Hawaii at Manoa, Department of Mechanical Engineering, Honolulu, HI (United States)

    2011-11-15

    Subsurface coherent structures and surface temperatures are investigated using simultaneous measurements of particle image velocimetry (PIV) and infrared (IR) thermography. Results for coherent structures from acoustic streaming and associated heating transfer in a rectangular tank with an acoustic horn mounted horizontally at the sidewall are presented. An observed vortex pair develops and propagates in the direction along the centerline of the horn. From the PIV velocity field data, distinct kinematic regions are found with the Lagrangian coherent structure (LCS) method. The implications of this analysis with respect to heat transfer and related sonochemical applications are discussed. (orig.)

  1. Acoustics of friction.

    Science.gov (United States)

    Akay, Adnan

    2002-04-01

    This article presents an overview of the acoustics of friction by covering friction sounds, friction-induced vibrations and waves in solids, and descriptions of other frictional phenomena related to acoustics. Friction, resulting from the sliding contact of solids, often gives rise to diverse forms of waves and oscillations within solids which frequently lead to radiation of sound to the surrounding media. Among the many everyday examples of friction sounds, violin music and brake noise in automobiles represent the two extremes in terms of the sounds they produce and the mechanisms by which they are generated. Of the multiple examples of friction sounds in nature, insect sounds are prominent. Friction also provides a means by which energy dissipation takes place at the interface of solids. Friction damping that develops between surfaces, such as joints and connections, in some cases requires only microscopic motion to dissipate energy. Modeling of friction-induced vibrations and friction damping in mechanical systems requires an accurate description of friction for which only approximations exist. While many of the components that contribute to friction can be modeled, computational requirements become prohibitive for their contemporaneous calculation. Furthermore, quantification of friction at the atomic scale still remains elusive. At the atomic scale, friction becomes a mechanism that converts the kinetic energy associated with the relative motion of surfaces to thermal energy. However, the description of the conversion to thermal energy represented by a disordered state of oscillations of atoms in a solid is still not well understood. At the macroscopic level, friction interacts with the vibrations and waves that it causes. Such interaction sets up a feedback between the friction force and waves at the surfaces, thereby making friction and surface motion interdependent. Such interdependence forms the basis for friction-induced motion as in the case of

  2. NEAR-FIELD ACOUSTIC HOLOGRAPHY FOR SEMI-FREE ACOUSTIC FIELD BASED ON WAVE SUPERPOSITION APPROACH

    Institute of Scientific and Technical Information of China (English)

    LI Weibing; CHEN Jian; YU Fei; CHEN Xinzhao

    2006-01-01

    In the semi-free acoustic field, the actual acoustic pressure at any point is composed of two parts: The direct acoustic pressure and the reflected acoustic pressure. The general acoustic holographic theories and algorithms request that there is only the direct acoustic pressure contained in the pressure at any point on the hologram surface, consequently, they cannot be used to reconstruct acoustic source and predict acoustic field directly. To take the reflected pressure into consideration, near-field acoustic holography for semi-free acoustic field based on wave superposition approach is proposed to realize the holographic reconstruction and prediction of the semi-free acoustic field, and the wave superposition approach is adopted as a holographic transform algorithm. The proposed theory and algorithm are realized and verified with a numerical example,and the drawbacks of the general theories and algorithms in the holographic reconstruction and prediction of the semi-free acoustic field are also demonstrated by this numerical example.

  3. Cryogenic Acoustic Suppression Testing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed project will explore and test the feasibility and effectiveness of using a cryogenic fluid (liquid nitrogen) to facilitate acoustic suppression in a...

  4. Frequency Steered Acoustic Transducer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase II project is to fabricate, characterize, and verify performance of a new type of frequency steered acoustic transducer...

  5. ADAPTIVE ELLIPSOIDAL ACOUSTIC INFINITE ELEMENT

    Institute of Scientific and Technical Information of China (English)

    Yang Ruiliang; Wang Hongzhen

    2004-01-01

    It is shown that the basis of the ellipsoidal acoustic infinite element Burnett method,the multipole expansion,cannot represent real ellipsoidal acoustic field exactly.To solve the problem,a weight of angular direction is added to the multipole expansion.The comparison of the modified method and the prime method shows that the modified method can describe and solve the ellipsoidal acoustic field more accurately than ever.A dilating sphere is used to test the new method further.Unlike other infinite element methods,varied ratio of the ellipsoidal artificial boundary instead of sphere is used.The pressure value of the artificial boundary is utilized as the initial value of the new method.Then the radiating phenomena of the ellipsoidal acoustic field can be researched using the new method.These examples show the feasibility of the adaptive method.

  6. Frequency Steered Acoustic Transducer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project is to develop, fabricate, and characterize a novel frequency steered acoustic transducer (FSAT) for the...

  7. Reverberant Acoustic Test Facility (RATF)

    Data.gov (United States)

    Federal Laboratory Consortium — The very large Reverberant Acoustic Test Facility (RATF) at the NASA Glenn Research Center (GRC), Plum Brook Station, is currently under construction and is due to...

  8. Sea Turtle Acoustic Telemetry Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Acoustic tags were attached to sea turtles captured in various fishing gear and the animals are either actively or passively tracked

  9. HEAT RECUPERATION

    Directory of Open Access Journals (Sweden)

    S. L. Rovin

    2011-01-01

    Full Text Available Heat recovery is an effective method of shortening specific energy consumption. new constructions of recuperators for heating and cupola furnaces have been designed and successfully introduced. two-stage recuperator with computer control providing blast heating up to 600 °C and reducing fuel consumption by 30% is of special interest.

  10. Wave heating in magnetic flux tubes

    Science.gov (United States)

    Kalkofen, Wolfgang

    1990-01-01

    The bright chromosphere in the quiet sun is confined to magnetic elements (flux tubes), which are located in the interior of the supergranulation cells and within the network that surrounds the cells. The paper discusses the heating of the gas in the magnetic elements of the cell interior. These intranetwork flux tubes are closely associated with bright points, which are heated by large-amplitude compressive waves with periods near the acoustic cutoff that travel outward from the photosphere and dissipate their energy in the chromosphere. The energy flux of these long-period waves appears to be sufficient for the heating of the low and middle chromosphere in the bright points.

  11. Acoustically-driven microfluidic systems

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. Acoustic Postprocessing of Multibody Simulations

    OpenAIRE

    Carrarini, Antonio

    2009-01-01

    SIMPACK allows models including flexible bodies to be set up and simulated efficiently in up to very high, relevant acoustic frequency ranges. In this article, a postprocessor module for SIMPACK which computes the sound power of a generic vibrating flexible component (so called structure-borne sound) is presented. The computed quantity is an indicator of the acoustic behaviour of the component and can also be used as an input for subsequent computations of ...

  13. Acoustic Rectification in Dispersive Media

    Science.gov (United States)

    Cantrell, John H.

    2008-01-01

    It is shown that the shapes of acoustic radiation-induced static strain and displacement pulses (rectified acoustic pulses) are defined locally by the energy density of the generating waveform. Dispersive properties are introduced analytically by assuming that the rectified pulses are functionally dependent on a phase factor that includes both dispersive and nonlinear terms. The dispersion causes an evolutionary change in the shape of the energy density profile that leads to the generation of solitons experimentally observed in fused silica.

  14. Autonomous Adaptive Acoustic Relay Positioning

    Science.gov (United States)

    2013-09-01

    equipment construction and repair tasks [51]. Commercial ROVs range from large, versatile work-class vehicles like Soil Machine Dynamics (SMD) QUANTUM and...range-only formation control using teams of heterogeneous vehicles with wifi and acoustic communications. Shankar and Chitre formulated the multi-armed...acoustic communication and sensing by marine robots. IEEE Journal of Oceanographic Engineering, 38:522–533, 2013. [43] S. Shankar and Chitre. Tuning

  15. Acoustic Multipurpose Cargo Transfer Bag

    Science.gov (United States)

    Baccus, Shelley

    2015-01-01

    The Logistics Reduction (LR) project within the Advanced Exploration Systems (AES) program is tasked with reducing logistical mass and repurposing logistical items. Multipurpose Cargo Transfer Bags (MCTB) are designed to be the same external volume as a regular cargo transfer bag, the common logistics carrier for the International Space Station. After use as a cargo bag, the MCTB can be unzipped and unfolded to be reused. This Acoustic MCTBs transform into acoustic blankets after the initial logistics carrying objective is complete.

  16. Wheel of concert hall acoustics

    OpenAIRE

    Kuusinen, A.; Lokki, T.

    2017-01-01

    More than a hundred years of research on concert hall acoustics has provided an extensive list of attributes to describe and evaluate the perceptual aspects of sound in concert halls. This brief overview discusses the current knowledge, and presents a "wheel of concert hall acoustics" in which the main aspects are gathered together with the descriptive attributes that are commonly encountered in the research literature. Peer reviewed

  17. Biological Effects of Acoustic Cavitation

    Science.gov (United States)

    2007-11-02

    rectified diffusion. 56 III. STABLE CAVITATION A. Introduction There are manv areas associated with the biological effects of ultrasound in which the...used said as cavitation indicators. Further, if clinical ultrasound systems are found to be inducing cavitation , either stable or transient, it will...O BIOLOGICAL EFFECTS OF ACOUSTIC CAVITATION by Lawrence A. Crum -- Physical Acoustics Research Laboratory Department of Physics and Astronomy ’ CTE

  18. Study Acoustic Emissions from Composites

    Science.gov (United States)

    Walker, James; Workman,Gary

    1998-01-01

    The purpose of this work will be to develop techniques for monitoring the acoustic emissions from carbon epoxy composite structures at cryogenic temperatures. Performance of transducers at temperatures ranging from ambient to cryogenic and the characteristics of acoustic emission from composite structures will be studied and documented. This entire effort is directed towards characterization of structures used in NASA propulsion programs such as the X-33.

  19. Opto-acoustic cell permeation

    Energy Technology Data Exchange (ETDEWEB)

    Visuri, S R; Heredia, N

    2000-03-09

    Optically generated acoustic waves have been used to temporarily permeate biological cells. This technique may be useful for enhancing transfection of DNA into cells or enhancing the absorption of locally delivered drugs. A diode-pumped frequency-doubled Nd:YAG laser operating at kHz repetition rates was used to produce a series of acoustic pulses. An acoustic wave was formed via thermoelastic expansion by depositing laser radiation into an absorbing dye. Generated pressures were measured with a PVDF hydrophone. The acoustic waves were transmitted to cultured and plated cells. The cell media contained a selection of normally- impermeable fluorescent-labeled dextran dyes. Following treatment with the opto-acoustic technique, cellular incorporation of dyes, up to 40,000 Molecular Weight, was noted. Control cells that did not receive opto-acoustic treatment had unremarkable dye incorporation. Uptake of dye was quantified via fluorescent microscopic analysis. Trypan Blue membrane exclusion assays and fluorescent labeling assays confirmed the vitality of cells following treatment. This method of enhanced drug delivery has the potential to dramatically reduce required drug dosages and associated side effects and enable revolutionary therapies.

  20. Acoustical evaluation of preschool classrooms

    Science.gov (United States)

    Yang, Wonyoung; Hodgson, Murray

    2003-10-01

    An investigation was made of the acoustical environments in the Berwick Preschool, Vancouver, in response to complaints by the teachers. Reverberation times (RT), background noise levels (BNL), and in-class sound levels (Leq) were measured for acoustical evaluation in the classrooms. With respect to the measured RT and BNL, none of the classrooms in the preschool were acceptable according to the criteria relevant to this study. A questionnaire was administered to the teachers to assess their subjective responses to the acoustical and nonacoustical environments of the classrooms. Teachers agreed that the nonacoustical environments in the classrooms were fair, but that the acoustical environments had problems. Eight different classroom configurations were simulated to improve the acoustical environments, using the CATT room acoustical simulation program. When the surface absorption was increased, both the RT and speech levels decreased. RASTI was dependent on the volumes of the classrooms when the background noise levels were high; however, it depended on the total absorption of the classrooms when the background noise levels were low. Ceiling heights are critical as well. It is recommended that decreasing the volume of the classrooms is effective. Sound absorptive materials should be added to the walls or ceiling.

  1. Development of nondestructive evaluation techniques for high-temperature ceramic heat exchanger components. Tenth quarterly report, January-March 1980

    Energy Technology Data Exchange (ETDEWEB)

    Kupperman, D.S.; Yuhas, D.; Caines, M.J.

    1980-04-01

    The effectiveness of several conventional and unconventional NDE techniques for specific high-temperature ceramic components was determined. Techniques under study at ANL include dye-enhanced radiography, acoustic microscopy, conventional ultrasonic testing, acoustic-emission detection, acoustic impact testing, holography, interferometry, infrared scanning, internal friction measurements, and overload proof testing. The current effort involves SiC heat-exchanger tubes; previous ceramic NDE efforts at ANL have involved silicon-nitride gas-turbine rotors. Recent results on inspection of SiC heat-exchanger tubing by means of ultrasonic acoustic microscopy techniques and efforts initiated and planned for NDE of ceramic joints are discussed.

  2. Heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Craig, L.B.; Farma, A.J.

    1987-01-06

    This invention concerns a heat exchanger as used in a space heater, of the type in which hot exhaust gases transfer heat to water or the like flowing through a helical heat exchange coil. A significant improvement to the efficiency of the heat exchange occurring between the air and water is achieved by using a conduit for the water having external helical fluting such that the hot gases circulate along two paths, rather than only one. A preferred embodiment of such a heat exchanger includes a porous combustion element for producing radiant heat from a combustible gas, surrounded by a helical coil for effectively transferring the heat in the exhaust gas, flowing radially from the combustion element, to the water flowing through the coil. 4 figs.

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

    Directory of Open Access Journals (Sweden)

    Liu Liu

    2014-06-01

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

  4. Damage depth estimation on a fatigue loaded composite structure using thermography and acoustic emission

    Science.gov (United States)

    Zalameda, Joseph N.; Winfree, William P.; Horne, Michael R.

    2017-02-01

    Passive thermography and acoustic emission data were obtained on a three stringer panel during periodic fatigue loading. The acoustic emission data were mapped onto thermal data, revealing the cluster of acoustic emission event locations around the thermal signatures of interest. By combining both techniques, progression of damage growth is confirmed and areas of failure are identified. Furthermore, sudden changes in thermally measured damage growth related to a previously measured higher energy acoustic emission event are studied to determine damage depth. A thermal model with a periodic flux heat source is presented to determine the relationship between the damage depth and thermal response. The model results are compared to the measured data. Lastly, the practical application and limitations of this technique are discussed.

  5. Study of focusing characteristics of ultrasound for designing acoustic lens in ultrasonic moxibustion device

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Jae Hyun; Song, Sung Jin; Kim, Hak Joon [School of Mechanical Engineering, Sungkyunkwan University, Suwon (Korea, Republic of); Kim, Ki Bok [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2015-04-15

    Traditional moxibustion therapy can cause severe pain and leave scarring burns at the moxibustion site as it relies on the practitioner's subjective and qualitative treatment. Recently, ultrasound therapy has received attention as an alternative to moxibustion therapy owing to its objectiveness and quantitative nature. However, in order to convert ultrasound energy into heat energy, there is a need to precisely understand the ultrasound-focusing characteristics of the acoustic lens. Therefore, in this study, an FEM simulation was performed for acoustic lenses with different geometries a concave lens and zone lens as the geometry critically influences ultrasound focusing. The acoustic pressure field, amplitude, and focal point were also calculated. Furthermore, the performance of the fabricated acoustic lens was verified by a sound pressure measurement experiment.

  6. Surface acoustic wave microfluidics.

    Science.gov (United States)

    Ding, Xiaoyun; Li, Peng; Lin, Sz-Chin Steven; Stratton, Zackary S; Nama, Nitesh; Guo, Feng; Slotcavage, Daniel; Mao, Xiaole; Shi, Jinjie; Costanzo, Francesco; Huang, Tony Jun

    2013-09-21

    The recent introduction of surface acoustic wave (SAW) technology onto lab-on-a-chip platforms has opened a new frontier in microfluidics. The advantages provided by such SAW microfluidics are numerous: simple fabrication, high biocompatibility, fast fluid actuation, versatility, compact and inexpensive devices and accessories, contact-free particle manipulation, and compatibility with other microfluidic components. We believe that these advantages enable SAW microfluidics to play a significant role in a variety of applications in biology, chemistry, engineering and medicine. In this review article, we discuss the theory underpinning SAWs and their interactions with particles and the contacting fluids in which they are suspended. We then review the SAW-enabled microfluidic devices demonstrated to date, starting with devices that accomplish fluid mixing and transport through the use of travelling SAW; we follow that by reviewing the more recent innovations achieved with standing SAW that enable such actions as particle/cell focusing, sorting and patterning. Finally, we look forward and appraise where the discipline of SAW microfluidics could go next.

  7. Acoustic Signal Processing

    Science.gov (United States)

    Hartmann, William M.; Candy, James V.

    Signal processing refers to the acquisition, storage, display, and generation of signals - also to the extraction of information from signals and the re-encoding of information. As such, signal processing in some form is an essential element in the practice of all aspects of acoustics. Signal processing algorithms enable acousticians to separate signals from noise, to perform automatic speech recognition, or to compress information for more efficient storage or transmission. Signal processing concepts are the building blocks used to construct models of speech and hearing. Now, in the 21st century, all signal processing is effectively digital signal processing. Widespread access to high-speed processing, massive memory, and inexpensive software make signal processing procedures of enormous sophistication and power available to anyone who wants to use them. Because advanced signal processing is now accessible to everybody, there is a need for primers that introduce basic mathematical concepts that underlie the digital algorithms. The present handbook chapter is intended to serve such a purpose.

  8. Passive Acoustic Vessel Localization

    Science.gov (United States)

    Suwal, Pasang Sherpa

    This thesis investigates the development of a low-cost passive acoustic system for localizing moving vessels to monitor areas where human activities such as fishing, snorkeling and poaching are restricted. The system uses several off-the-shelf sensors with unsynchronized clocks where the Time Difference of Arrival (TDOA) or time delay is extracted by cross-correlation of the signal between paired sensors. The cross-correlation function uses phase correlation or Phase Transform (PHAT) which whitens the cross-spectrum in order to de-emphasize dominant frequency components. Using the locations of pairs of sensors as foci, hyperbolic equations can be defined using the time delay between them. With three or more sensors, multiple hyperbolic functions can be calculated which intersect at a unique point: the boat's location. It is also found that increasing separation distances between sensors decreased the correlation between the signals. However larger separation distances have better localization capability than with small distances. Experimental results from the Columbia and Willamette Rivers are presented to demonstrate performance.

  9. Covert underwater acoustic communications.

    Science.gov (United States)

    Ling, Jun; He, Hao; Li, Jian; Roberts, William; Stoica, Petre

    2010-11-01

    Low probability of detection (LPD) communications are conducted at a low received signal-to-noise ratio (SNR) to deter eavesdroppers to sense the presence of the transmitted signal. Successful detection at intended receiver heavily relies on the processing gain achieved by employing the direct-sequence spread-spectrum (DSSS) technique. For scenarios that lack a sufficiently low SNR to maintain LPD, another metric, referred to as low probability of interception (LPI), is of interest to protect the privacy of the transmitted information. If covert communications take place in underwater acoustic (UWA) environments, then additional challenges are present. The time-varying nature of the UWA channel prevents the employment of a long spreading waveform. Furthermore, UWA environments are frequency-selective channels with long memory, which imposes challenges to the design of the spreading waveform. In this paper, a covert UWA communication system that adopts the DSSS technique and a coherent RAKE receiver is investigated. Emphasis is placed on the design of a spreading waveform that not only accounts for the transceiver structure and frequency-selective nature of the UWA channel, but also possesses a superior LPI. The proposed techniques are evaluated using both simulated and SPACE'08 in-water experimental data.

  10. Focusing of Acoustic Waves through Acoustic Materials with Subwavelength Structures

    KAUST Repository

    Xiao, Bingmu

    2013-05-01

    In this thesis, wave propagation through acoustic materials with subwavelength slits structures is studied. Guided by the findings, acoustic wave focusing is achieved with a specific material design. By using a parameter retrieving method, an effective medium theory for a slab with periodic subwavelength cut-through slits is successfully derived. The theory is based on eigenfunction solutions to the acoustic wave equation. Numerical simulations are implemented by the finite-difference time-domain (FDTD) method for the two-dimensional acoustic wave equation. The theory provides the effective impedance and refractive index functions for the equivalent medium, which can reproduce the transmission and reflection spectral responses of the original structure. I analytically and numerically investigate both the validity and limitations of the theory, and the influences of material and geometry on the effective spectral responses are studied. Results show that large contrasts in impedance and density are conditions that validate the effective medium theory, and this approximation displays a better accuracy for a thick slab with narrow slits in it. Based on the effective medium theory developed, a design of a at slab with a snake shaped" subwavelength structure is proposed as a means of achieving acoustic focusing. The property of focusing is demonstrated by FDTD simulations. Good agreement is observed between the proposed structure and the equivalent lens pre- dicted by the theory, which leads to robust broadband focusing by a thin at slab.

  11. Reflective echo tomographic imaging using acoustic beams

    Energy Technology Data Exchange (ETDEWEB)

    Kisner, Roger; Santos-Villalobos, Hector J

    2014-11-25

    An inspection system includes a plurality of acoustic beamformers, where each of the plurality of acoustic beamformers including a plurality of acoustic transmitter elements. The system also includes at least one controller configured for causing each of the plurality of acoustic beamformers to generate an acoustic beam directed to a point in a volume of interest during a first time. Based on a reflected wave intensity detected at a plurality of acoustic receiver elements, an image of the volume of interest can be generated.

  12. Acoustic loading effects on oscillating rod bundles

    Energy Technology Data Exchange (ETDEWEB)

    Lin, W.H.

    1980-01-01

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

  13. The acoustics of diagnostic microbubbles: dissipative effects and heat deposition

    NARCIS (Netherlands)

    Hilgenfeldt, Sascha; Lohse, Detlef

    2000-01-01

    We discuss the effectively detectable scattered intensity of ultrasound from diagnostic microbubble suspensions, taking dissipative mechanisms in the liquid medium into account. In particular, we conclude that neither non-linear wave steepening of the incident (driving) wave nor of the outgoing (sca

  14. Surface-acoustic-wave (SAW) flow sensor

    Science.gov (United States)

    Joshi, Shrinivas G.

    1991-03-01

    The use of a surface-acoustic-wave (SAW) device to measure the rate of gas flow is described. A SAW oscillator heated to a suitable temperature above ambient is placed in the path of a flowing gas. Convective cooling caused by the gas flow results in a change in the oscillator frequency. A 73-MHz oscillator fabricated on 128 deg rotated Y-cut lithium niobate substrate and heated to 55 C above ambient shows a frequency variation greater than 142 kHz for flow-rate variation from 0 to 1000 cu cm/min. The output of the sensor can be calibrated to provide a measurement of volume flow rate, pressure differential across channel ports, or mass flow rate. High sensitivity, wide dynamic range, and direct digital output are among the attractive features of this sensor. Theoretical expressions for the sensitivity and response time of the sensor are derived. It is shown that by using ultrasonic Lamb waves propagating in thin membranes, a flow sensor with faster response than a SAW sensor can be realized.

  15. Sonification of acoustic emission data

    Science.gov (United States)

    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

  16. Acoustic constituents of prosodic typology

    Science.gov (United States)

    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

  17. Acoustic valve leak detection: Initial program development, implementation & experience

    Energy Technology Data Exchange (ETDEWEB)

    Wicker, G.L. [Baltimore Gas and Electric Company, Baltimore, MD (United States)

    1996-07-01

    Acoustic valve leak detection is one of the many test techniques employed in modern power plants with active predictive maintenance programs. In 1994, a valve leak detection program was implemented within Baltimore Gas and Electric`s Fossil Energy Division. Within two years, the program resulted in energy savings in excess of one million dollars. The leak detection program has become an essential technology that has reduced plant heat rate losses, prevented unnecessary valve maintenance and increased plant awareness of potential losses. This paper describes program development, implementation and test methodology of Baltimore Gas and Electric`s acoustic leak detection program. Key topics include equipment description, program measurements, methodology and leak identification methods. The paper also will include discussion on the practical approach of equipment selection and program philosophies.

  18. CALCULATION OF ACOUSTIC EFFICIENCY OF PORTABLE ACOUSTIC SCREEN

    Directory of Open Access Journals (Sweden)

    Aleksandr Skvortsov

    2016-03-01

    Full Text Available The research of influence of life environment adverse factors on physical development and health of population is an actual problem of ecology. The aspects of the most actual problems of the modern world, namely environmental industrial noise pollution are considered in the article. Industrial facilities everywhere have noisy equipment. Noise is a significant factors of negative influenceon people and environment. Combined effects of noise and of other physical pollutions on people may cause amplification of their negative impact. If the noise pollution level from the object in a residential area exceeds the permissible levels (MPL, noise protection measures can be initiated. Today, the most common design decisions for noise protection are sound absorbing construction, noise screens and barriers, acousting housings, soundproff cabins. Many of them are popular, others are less known. The article deals with one of the most wide spread means of noise protection – a portable acoustic screen. The aim of the research is to determine the efficiency of portable acoustic screens. It is shown that the installation of such structures can reduce the average value of the sound level. The authors analyzed acoustic screens as device to reduce noise pollution. The authors offer a potable acoustic screen differing from the used easyness, mobility, minimum price and good sound protective properties. Effectiveness, a sound absorption coefficient and sound conductivity coefficient of a portable acoustic screen are evaluated. The descriptions of the algorithm calculations and the combination of technical solutions have practical originality. The results of the research demonstrate the advantages of the proposed solutions for reducing noise levels in the agro-industrial complex.

  19. Neural correlates of acoustic reasoning.

    Science.gov (United States)

    Fangmeier, Thomas; Knauff, Markus

    2009-01-16

    We report an fMRI experiment on deductive reasoning with acoustically presented problems. Twelve volunteers received problems in which an acoustic stimulus came from the left or the right of another stimulus. The participants then heard a third stimulus coming from the left or the right of one of the proceeding stimuli. Their task was to determine the spatial relation between the two stimuli they never perceived together. In the psychology of reasoning, such problems are called transitive inferences or three-term-series problems. During the early phases of the inference, activity in primary and secondary acoustic areas and in the anterior prefrontal cortex was found. Further processing was accompanied by activity in medial frontal gyrus, the cingulate cortex, and in the parietal cortex. In the final phase, activity was found in the left frontal cortex, the right cerebellum, the right superior temporal gyrus, and in the parietal lobule. These results show that different brain areas are related to different phases of an inference. Based on these findings, we propose a three-stage-model of acoustic reasoning and identify the neural structures that are involved in the cognitive processes taking place in each phase. The results also show how acoustically presented reasoning problems differ from problems in which the problems are presented visually.

  20. Virtual acoustic displays

    Science.gov (United States)

    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

  1. Acoustic transparency and slow sound using detuned acoustic resonators

    DEFF Research Database (Denmark)

    Santillan, Arturo Orozco; Bozhevolnyi, Sergey I.

    2011-01-01

    We demonstrate that the phenomenon of acoustic transparency and slowsound propagation can be realized with detuned acoustic resonators (DAR), mimicking thereby the effect of electromagnetically induced transparency (EIT) in atomic physics. Sound propagation in a pipe with a series of side......-attached DAR, with adjacent DAR units spaced by a distance much smaller than the wavelength, is analyzed. We show that such a chain of DAR units forms an analog of one-dimensional (1D) metamaterial with unique properties of dispersion and transmission, revealing the possibility of slowing sound (at 2 kHz) down...

  2. Validation of an approximate model for the thermal behavior in acoustically driven bubbles

    NARCIS (Netherlands)

    Stricker, L.; Stricker, Laura; Prosperetti, Andrea; Lohse, Detlef

    2011-01-01

    The chemical production of radicals inside acoustically driven bubbles is determined by the local temperature inside the bubbles. Therefore, modeling of chemical reaction rates in bubbles requires an accurate evaluation of the temperature field and the heat exchange with the liquid. The aim of the

  3. Certification of the boilers acoustic performance; Certification des performances acoustiques des chaudieres. Confort et performances du batiment

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-07-01

    In order to control the noise pollution, a certification has been implemented on the heating installations. So a meeting has been devoted to this topic to show that the certification initiative will allow to design new systems in regards to the acoustic regulation. The context and the application domain of the new acoustic regulation, the technical aspects, the implementing of new systems and some examples of solutions are presented. (A.L.B.)

  4. Acoustic remote sensing of ocean flows

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; Desa, E.

    Acoustic techniques have become powerful tools for measurement of ocean circulation mainly because of the ability of acoustic signals to travel long distances in water, and the inherently non-invasive nature of measurement. The satellite remote...

  5. Golden Gate and Pt. Reyes Acoustic Detections

    Data.gov (United States)

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

  6. On Architectural Acoustics Design using Computer Simulation

    DEFF Research Database (Denmark)

    Schmidt, Anne Marie Due; Kirkegaard, Poul Henning

    2004-01-01

    is to investigate the field of application an acoustic simulation program can have during an architectural acoustics design process. A case study is carried out in order to represent the iterative working process of an architect. The working process is divided into five phases and represented by typical results......The acoustical quality of a given building, or space within the building, is highly dependent on the architectural design. Architectural acoustics design has in the past been based on simple design rules. However, with a growing complexity in the architectural acoustic and the emergence of potent...... room acoustic simulation programs it is now possible to subjectively analyze and evaluate acoustic properties prior to the actual construction of a facility. With the right tools applied, the acoustic design can become an integrated part of the architectural design process. The aim of the present paper...

  7. Acoustic network event classification using swarm optimization

    Science.gov (United States)

    Burman, Jerry

    2013-05-01

    Classifying acoustic signals detected by distributed sensor networks is a difficult problem due to the wide variations that can occur in the transmission of terrestrial, subterranean, seismic and aerial events. An acoustic event classifier was developed that uses particle swarm optimization to perform a flexible time correlation of a sensed acoustic signature to reference data. In order to mitigate the effects from interference such as multipath, the classifier fuses signatures from multiple sensors to form a composite sensed acoustic signature and then automatically matches the composite signature with reference data. The approach can classify all types of acoustic events but is particularly well suited to explosive events such as gun shots, mortar blasts and improvised explosive devices that produce an acoustic signature having a shock wave component that is aperiodic and non-linear. The classifier was applied to field data and yielded excellent results in terms of reconstructing degraded acoustic signatures from multiple sensors and in classifying disparate acoustic events.

  8. Acoustic Communication for Medical Nanorobots

    CERN Document Server

    Hogg, Tad

    2012-01-01

    Communication among microscopic robots (nanorobots) can coordinate their activities for biomedical tasks. The feasibility of in vivo ultrasonic communication is evaluated for micron-size robots broadcasting into various types of tissues. Frequencies between 10MHz and 300MHz give the best tradeoff between efficient acoustic generation and attenuation for communication over distances of about 100 microns. Based on these results, we find power available from ambient oxygen and glucose in the bloodstream can readily support communication rates up to 10,000 bits/second between micron-sized robots. We discuss techniques, such as directional acoustic beams, that can increase this rate. The acoustic pressure fields enabling this communication are unlikely to damage nearby tissue, and short bursts at considerably higher power could be of therapeutic use.

  9. Classroom acoustics: Three pilot studies

    Science.gov (United States)

    Smaldino, Joseph J.

    2005-04-01

    This paper summarizes three related pilot projects designed to focus on the possible effects of classroom acoustics on fine auditory discrimination as it relates to language acquisition, especially English as a second language. The first study investigated the influence of improving the signal-to-noise ratio on the differentiation of English phonemes. The results showed better differentiation with better signal-to-noise ratio. The second studied speech perception in noise by young adults for whom English was a second language. The outcome indicated that the second language learners required a better signal-to-noise ratio to perform equally to the native language participants. The last study surveyed the acoustic conditions of preschool and day care classrooms, wherein first and second language learning occurs. The survey suggested an unfavorable acoustic environment for language learning.

  10. Software-based acoustical measurements

    CERN Document Server

    Miyara, Federico

    2017-01-01

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

  11. Phoneme Recognition Using Acoustic Events

    CERN Document Server

    Huebener, K; Huebener, Kai; Carson-Berndsen, Julie

    1994-01-01

    This paper presents a new approach to phoneme recognition using nonsequential sub--phoneme units. These units are called acoustic events and are phonologically meaningful as well as recognizable from speech signals. Acoustic events form a phonologically incomplete representation as compared to distinctive features. This problem may partly be overcome by incorporating phonological constraints. Currently, 24 binary events describing manner and place of articulation, vowel quality and voicing are used to recognize all German phonemes. Phoneme recognition in this paradigm consists of two steps: After the acoustic events have been determined from the speech signal, a phonological parser is used to generate syllable and phoneme hypotheses from the event lattice. Results obtained on a speaker--dependent corpus are presented.

  12. Acoustic Localization with Infrasonic Signals

    Science.gov (United States)

    Threatt, Arnesha; Elbing, Brian

    2015-11-01

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

  13. Acoustic multivariate condition monitoring - AMCM

    Energy Technology Data Exchange (ETDEWEB)

    Rosenhave, P.E. [Vestfold College, Maritime Dept., Toensberg (Norway)

    1997-12-31

    In Norway, Vestfold College, Maritime Department presents new opportunities for non-invasive, on- or off-line acoustic monitoring of rotating machinery such as off-shore pumps and diesel engines. New developments within acoustic sensor technology coupled with chemometric data analysis of complex signals now allow condition monitoring of hitherto unavailable flexibility and diagnostic specificity. Chemometrics paired with existing knowledge yields a new and powerful tool for condition monitoring. By the use of multivariate techniques and acoustics it is possible to quantify wear and tear as well as predict the performance of working components in complex machinery. This presentation describes the AMCM method and one result of a feasibility study conducted onboard the LPG/C `Norgas Mariner` owned by Norwegian Gas Carriers as (NGC), Oslo. (orig.) 6 refs.

  14. Absorption boundary conditions for geomertical acoustics

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2012-01-01

    Defining accurate acoustical boundary conditions is of crucial importance for room acoustic simulations. In predicting sound fields using phased geometrical acoustics methods, the absorption coefficients or surface impedances of the boundary surfaces can be used, but no guideline has been developed...... solutions. Two rectangular rooms with uniform and non-uniform absorption distributions are tested. It is concluded that the impedance and random incidence absorption boundary conditions produce reasonable results with some exceptions at low frequencies for acoustically soft materials....

  15. Particle analysis in an acoustic cytometer

    Energy Technology Data Exchange (ETDEWEB)

    Kaduchak, Gregory; Ward, Michael D

    2012-09-18

    The present invention is a method and apparatus for acoustically manipulating one or more particles. Acoustically manipulated particles may be separated by size. The particles may be flowed in a flow stream and acoustic radiation pressure, which may be radial, may be applied to the flow stream. This application of acoustic radiation pressure may separate the particles. In one embodiment, the particles may be separated by size, and as a further example, the larger particles may be transported to a central axis.

  16. Acoustic behaviors of unsaturated soils

    Science.gov (United States)

    Lu, Z.

    2011-12-01

    Soils are unconsolidated granular materials, consisting of solid particles, water and air. Their mechanical and dynamic behaviors are determined by the discrete nature of the media as well as external and inter-particle forces. For unsaturated soils, two factors significantly affect soils acoustic/seismic responses: external pressure and internal water potential/matric suction. In triaxial cell tests, unsaturated soils were subjected to predefined stress paths to undergo stages of normal consolidation, unload-reload cycles, and failure. The stress deformation curve and stress-P-wave velocity were measured and compared. The study revealed that soil's dynamic response to external pressure are similar to those of the load-deformation behaviors and demonstrated that acoustic velocity can be used to monitor the state of stress of soils. In a long term field soil survey, the P-wave velocities were found to be correlated with water potential as expressed as a power-law relationship. The above phenomena can be understood by using the Terzaghi' s the principle of effective stress. The measured results were in good agreement with Brutsaert theory. The effective stress concept can also be applied to explain the observations in a soil pipe flow study in which soil internal erosion processes were monitored and interpreted by the temporal evolution of the P-wave velocity. In addition to above linear acoustic behaviors, soils, like other earth materials, exhibit astonishing non-classical nonlinear behaviors such as end-point memory, hysteresis, strain -dependent shear modulus, resonant frequency shift, and phase shift, harmonics generation, etc. A nonlinear acoustic study of a soil as a function of water content showed that the nonlinear acoustic parameter are much sensitive to the variations of soil water content than that of the acoustic velocity.

  17. CT findings of acoustic neuroma

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Do Choul; Lee, Jae Mun; Shinn, Kyung Sub; Bahk, Yong Whee [Catholic Univ., Seoul (Korea, Republic of)

    1987-10-15

    Computed Tomography (CT) is very accurate in evaluating the location, size, shape and extension of acoustic neuroma. We analysed CT findings of 23 acoustic neuromas seen at Department of Radiology, Kangnam St. Mary's Hospital, Catholic University Medical College during the period of from January 1981 to June 1987. 1. Five (22%) were men and 18 (78%) were women with the high incidence occurring in the 4th and 5th decades. 2. Twenty two cases were diagnosed satisfactorily by CT examinations which included axial, coronal and reconstruction images. One with the smallest dimension of 8 mm in diameter could not be detected by the conventional CT scan. But is could be seen after metrizamide cisternography. mean size of the tumor masses was estimated 3.6 cm in diameter. 3. The shape of the tumor was oval in 50%, round in 27% and lobulated in 23%. The masses were presented as hypodense in 50%, isodense in 32% and hyperdense in 18%. All tumors were extended from the internal acoustic and toward the cerebellopontine angle. The internal acoustic canal was widened in 77%. Hydrocephalus was associated in 45%. Widening of cerebellopontine angle cistern was noted in 50%. 4. After contrast infusion the tumors were enhanced markedly in 45%, moderately in 32% and mildly in 23%. The enhanced pattern was homogeneous in 41%, mixed in 41% and rim in 18%. The margin of the tumors was sharply defined in 82%. The tumors were attached to the petrous bone with acute angle in 73%. Cystic change within the tumor was found in 27%. The peritumoral edema was noted in 45%. In conclusion, CT is of most effective modalities to evaluate size, shape, extent and internal architecture of acoustic neuroma as well as relationship with adjacent anatomic structures including the internal acoustic canal.

  18. Acoustically-Induced Electrical Signals

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2014-01-01

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

  20. Acoustic-gravity nonlinear structures

    Directory of Open Access Journals (Sweden)

    D. Jovanović

    2002-01-01

    Full Text Available A catalogue of nonlinear vortex structures associated with acoustic-gravity perturbations in the Earth's atmosphere is presented. Besides the previously known Kelvin-Stewart cat's eyes, dipolar and tripolar structures, new solutions having the form of a row of counter-rotating vortices, and several weakly two-dimensional vortex chains are given. The existence conditions for these nonlinear structures are discussed with respect to the presence of inhomogeneities of the shear flows. The mode-coupling mechanism for the nonlinear generation of shear flows in the presence of linearly unstable acoustic-gravity waves, possibly also leading to intermittency and chaos, is presented.

  1. Acoustic performance of membrane absorbers

    Science.gov (United States)

    Frommhold, W.; Fuchs, H. V.; Sheng, S.

    1994-03-01

    This paper is a report on the acoustic properties of absorbing elements, which consist of metal membranes and show good sound absorption at low and medium frequencies over more than one octave. The studies refer to the sound absorption coefficient and acoustic impedance at normal incidence of the sound waves. It is shown that the behavior of the absorbing element is mainly determined by a combination of Helmholtz resonance and plate resonance. The parameters of the separate resonators are determined both by theory and experiment and serve as input data for a simplified calculation model, which can be used as an auxiliary tool for designing membrane absorber silencers.

  2. Physical foundations of technical acoustics

    CERN Document Server

    Malecki, I

    1969-01-01

    Physical Foundations of Technical Acoustics discusses theoretical foundations of acoustical engineering. It is not so much a technical compendium as a systematic statement of physical laws so conceived that technologists might find in it all the information they need to become acquainted with the physical meaning and mathematical expression of phenomena they encounter in their work. To facilitate the acquirement of notions, which lie beyond a layman's grasp, the plan of narration adopted consists in beginning with the simplest idealized cases and then gradually moving on to the truest possibl

  3. Predicting and auralizing acoustics in classrooms

    DEFF Research Database (Denmark)

    Christensen, Claus Lynge

    2005-01-01

    Although classrooms have fairly simple geometries, this type of room is known to cause problems when trying to predict their acoustics using room acoustics computer modeling. Some typical features from a room acoustics point of view are: Parallel walls, low ceilings (the rooms are flat), uneven...

  4. Aero-acoustic Computations of Wind Turbines

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Michelsen, Jess; Sørensen, Jens Nørkær

    2002-01-01

    A numerical algorithm for acoustic noise generation is extended to 3D flows. The approach involves two parts comprising a viscous incompressible flow part and an inviscid acoustic part. In order to simulate noise generated from a wind turbine, the incompressible and acoustic equations are written...

  5. On Architectural Acoustics Design using Computer Simulation

    DEFF Research Database (Denmark)

    Schmidt, Anne Marie Due; Kirkegaard, Poul Henning

    2004-01-01

    The acoustical quality of a given building, or space within the building, is highly dependent on the architectural design. Architectural acoustics design has in the past been based on simple design rules. However, with a growing complexity in the architectural acoustic and the emergence of potent...

  6. Location of an acoustic window in dolphins.

    Science.gov (United States)

    Popov, V V; Supin, A Y

    1990-01-15

    Auditory brainstem responses (ABR) to sound clicks from sources in different positions were recorded in dolphins Inia geoffrensis. The position of the acoustic window was determined by measurement of acoustic delays. The acoustic window was found to lie close to the auditory meatus and the bulla rather than on the lower jaw.

  7. Outdoor Acoustics as a General Discipline

    DEFF Research Database (Denmark)

    Rasmussen, Karsten Bo

    1999-01-01

    A tutorial paper exploring the characteristics of sound outdoors. Outdoor acoustics is contrasted to room acoustics. A number of important aspects of outdoor acoustics are exemplified and theoretical approaches are outlined. These are influence of ground impedance, influence of weather, screening...

  8. From Architectural Acoustics to Acoustical Architecture Using Computer Simulation

    DEFF Research Database (Denmark)

    Schmidt, Anne Marie Due; Kirkegaard, Poul Henning

    2005-01-01

    acoustic design process and to set up a strategy to develop future programmes. The emphasis is put on the first three out of four phases in the working process of the architect and a case study is carried out in which each phase is represented by typical results ? as exemplified with reference...

  9. Detecting acoustic events during thermal and mechanical loading

    Energy Technology Data Exchange (ETDEWEB)

    Por, Gabor; Bereczki, Peter; Danka, Zsolt; Trampus, Peter [College of Dunaujvaros (Hungary)

    2014-11-01

    We examined Acoustic Emission (AE) events during combined heat and tensile test carried out in different steels (S235JRG2, TRIP and TWIP steels) on Gleeble simulator. The simulator enabled us to control parameters for fast heating and cooling parallel with pressing and tensile the sample until its real break. The aim was to investigate the structural change of the material, phase transformation in the steel at different temperatures, and connect them to signatures measured by acoustic emission sensors. During testing we noticed characteristics of Barkhausen noise. We demonstrate and prove definitely that we were facing Acoustic Barkhausen Noise (ABN) due to AC current used to heating and to maintaining the temperature in the cylindrical ferritic sample. It was observed, that the magnitude of the ABN dropped suddenly to the half when the tensile test started after preheating, and it was growing back when the tensile test went to plastic deformation with elongation of the tested sample. Localization of the ABN sources has been done showing the distribution of the sources along the whole material. ABN sources were observed all along the sample with interesting density growth in the section where the diameter was smaller, thus the tension was higher. Nevertheless, this was not the only observation, since the place of the densest sources was displaced from one position to another position until the break occurred near to the densest place of ANB and AE source. Off-line examination of the structure of material afterward using destructive test proved that we could register those cooling periods, where phase transition took place in the material. Ferrite-bainite and magnetite-bainite transitions were connected to some higher distribution of ANB and AE signals during the test. Rate of hits and sum of hit were connected to material transition during cooling. The first results of AE measurements during tensile test in TWIP materials showed that AE events are connected with

  10. Sustainable New Brick and Thermo-Acoustic Insulation Panel from Mineralization of Stranded Driftwood Residues

    Directory of Open Access Journals (Sweden)

    Anna Laura Pisello

    2016-08-01

    Full Text Available There is considerable interest recently in by-products for application in green buildings. These materials are widely used as building envelope insulators or blocks. In this study, an experimental study was conducted to test stranded driftwood residues as raw material for possible thermo-acoustic insulation panel and environmentally sustainable brick. The thermal and acoustic characteristics of such a natural by-product were examined. Part of samples were mineralized by means of cement-based additive to reinforce the material and enhance its durability as well as fire resistance. Several mixtures with different sizes of ground wood chips and different quantities of cement were investigated. The thermo-acoustic in-lab characterization was aimed at investigating the thermal conductivity, thermal diffusivity, volumetric specific heat, and acoustic transmission loss. All samples were tested before and after mineralization. Results from this study indicate that it is possible to use stranded driftwood residues as building materials with competitive thermo-acoustic properties. In fact, the thermal conductivity was shown to be always around 0.07 W/mK in the unbound samples, and around double that value for the mineralized samples, which present a much higher volumetric specific heat (1.6 MJ/m3K and transmission loss capability. The lignin powder showed a sort of intermediate behavior between the unbound and the mineralized samples.

  11. Heat pipes

    CERN Document Server

    Dunn, Peter D

    1994-01-01

    It is approximately 10 years since the Third Edition of Heat Pipes was published and the text is now established as the standard work on the subject. This new edition has been extensively updated, with revisions to most chapters. The introduction of new working fluids and extended life test data have been taken into account in chapter 3. A number of new types of heat pipes have become popular, and others have proved less effective. This is reflected in the contents of chapter 5. Heat pipes are employed in a wide range of applications, including electronics cooling, diecasting and injection mo

  12. Satellite and acoustic tracking device

    KAUST Repository

    Berumen, Michael L.

    2014-02-20

    The present invention relates a method and device for tracking movements of marine animals or objects in large bodies of water and across significant distances. The method and device can track an acoustic transmitter attached to an animal or object beneath the ocean surface by employing an unmanned surface vessel equipped with a hydrophone array and GPS receiver.

  13. Numerical investigation of acoustic solitons

    CERN Document Server

    Lombard, Bruno; Richoux, Olivier

    2014-01-01

    Acoustic solitons can be obtained by considering the propagation of large amplitude sound waves across a set of Helmholtz resonators. The model proposed by Sugimoto and his coauthors has been validated experimentally in previous works. Here we examine some of its theoretical properties: low-frequency regime, balance of energy, stability. We propose also numerical experiments illustrating typical features of solitary waves.

  14. Longitudinal bulk acoustic mass sensor

    DEFF Research Database (Denmark)

    Hales, Jan Harry; Teva, Jordi; Boisen, Anja

    2009-01-01

    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(-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...

  15. Topology optimization for acoustic problems

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    2006-01-01

    In this paper a method to control acoustic properties in a room with topology optimization is presented. It is shown how the squared sound pressure amplitude in a certain part of a room can be minimized by distribution of material in a design domain along the ceiling in 2D and 3D. Nice 0-1 designs...

  16. MTCI acoustic agglomeration particulate control

    Energy Technology Data Exchange (ETDEWEB)

    Chandran, R.R.; Mansour, M.N. [Manufacturing and Technology Conversion International, Inc., Columbia, MD (United States); Scaroni, A.W.; Koopmann, G.H. [Pennsylvania State Univ., University Park, PA (United States); Loth, J.L. [West Virginia Univ., Morgantown, WV (United States)

    1994-10-01

    The overall objective of this project is to demonstrate pulse combination induced acoustic enhancement of coal ash agglomeration and sulfur capture at conditions typical of direct coal-fired turbines and PFBC hot gas cleanup. MTCI has developed an advanced compact pulse combustor island for direct coal-firing in combustion gas turbines. This combustor island comprises a coal-fired pulse combustor, a combined ash agglomeration and sulfur capture chamber (CAASCC), and a hot cyclone. In the MTCI proprietary approach, the pulse combustion-induced high intensity sound waves improve sulfur capture efficiency and ash agglomeration. The resulting agglomerates allow the use of commercial cyclones and achieve very high particulate collection efficiency. In the MTCI proprietary approach, sorbent particles are injected into a gas stream subjected to an intense acoustic field. The acoustic field serves to improve sulfur capture efficiency by enhancing both gas film and intra-particle mass transfer rates. In addition, the sorbent particles act as dynamic filter foci, providing a high density of stagnant agglomerating centers for trapping the finer entrained (in the oscillating flow field) fly ash fractions. A team has been formed with MTCI as the prime contractor and Penn State University and West Virginia University as subcontractors to MTCI. MTCI is focusing on hardware development and system demonstration, PSU is investigating and modeling acoustic agglomeration and sulfur capture, and WVU is studying aerovalve fluid dynamics. Results are presented from all three studies.

  17. Murray Strasberg and bubble acoustics

    NARCIS (Netherlands)

    Prosperetti, Andrea

    2014-01-01

    Murray Strasberg made seminal contributions to the nucleation and acoustics of bubbles. Half a century after publication, these papers still receive a sizable number of citations every year. The talk will review this work, comment on its impact, and put Strasberg's classical results in a modern

  18. Acoustic Liner for Turbomachinery Applications

    Science.gov (United States)

    Huff, Dennis L.; Sutliff, Daniel L.; Jones, Michael G.; Hebsur, Mohan G.

    2010-01-01

    The purpose of this innovation is to reduce aircraft noise in the communities surrounding airports by significantly attenuating the noise generated by the turbomachinery, and enhancing safety by providing a containment barrier for a blade failure. Acoustic liners are used in today's turbofan engines to reduce noise. The amount of noise reduction from an acoustic liner is a function of the treatment area, the liner design, and the material properties, and limited by the constraints of the nacelle or casement design. It is desirable to increase the effective area of the acoustic treatment to increase noise suppression. Modern turbofan engines use wide-chord rotor blades, which means there is considerable treatment area available over the rotor tip. Turbofan engines require containment over the rotors for protection from blade failure. Traditional methods use a material wrap such as Kevlar integrated with rub strips and sometimes metal layers (sandwiches). It is possible to substitute the soft rub-strip material with an open-cell metallic foam that provides noise-reduction benefits and a sacrificial material in the first layer of the containment system. An open-cell foam was evaluated that behaves like a bulk acoustic liner, serves as a tip rub strip, and can be integrated with a rotor containment system. Foams can be integrated with the fan-containment system to provide sufficient safety margins and increased noise attenuation. The major innovation is the integration of the foam with the containment.

  19. Fundamentals of Acoustic Backscatter Imagery

    Science.gov (United States)

    2011-09-20

    41 6.12 Geocoding ...47 7.6 Errors in Geocoding .............................................................................................................. 47...h = z - R cos6 (39a) and x = rt sin6. (39b) 6.12 Geocoding Acoustic backscatter imagery data are collected by recording the across-track signals

  20. Acoustic Absorption Characteristics of People.

    Science.gov (United States)

    Kingsbury, H. F.; Wallace, W. J.

    1968-01-01

    The acoustic absorption characteristics of informally dressed college students in typical classroom seating are shown to differ substantially from data for formally dressed audiences in upholstered seating. Absorption data, expressed as sabins per person or absorption coefficient per square foot, shows that there is considerable variation between…

  1. Acoustical coupling of lizard eardrums

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, Jakob; Manley, Geoffrey A

    2008-01-01

    Lizard ears are clear examples of two-input pressure-difference receivers, with up to 40-dB differences in eardrum vibration amplitude in response to ipsi- and contralateral stimulus directions. The directionality is created by acoustical coupling of the eardrums and interaction of the direct and...

  2. APL - North Pacific Acoustic Laboratory

    Science.gov (United States)

    2011-09-01

    the roles of internal waves, ocean spice, internal tides, fronts and eddies in causing fluctuations in acoustic receptions. 5. To improve basin-scale...Farmer, R. Gentry, T. Gross, A. Hawkins, F.~Li, K. Metcalf , J.H. Miller, D. Moretti, C. Rodrigo, and T. Shinke, (2011). “An International Quiet

  3. Acoustic Climb to Cruise Test

    Science.gov (United States)

    1991-01-01

    Flight test film footage of three different aircraft testing the acoustical noise levels during take-off, climb, maneuvers, and touch and go landings are described. These sound tests were conducted on two fighter aircraft and one cargo aircraft. Results from mobile test vehicle are shown.

  4. Acoustics SIMOPS: managing the unnecessary

    Energy Technology Data Exchange (ETDEWEB)

    Hanton, Samuel John [Nautronix Marine Technology Solutions, Rio de Janeiro, RJ (Brazil)

    2012-07-01

    Time is money, and offshore operations are expensive. The desire therefore, is to increase efficiency through the condensing of schedules. This inevitably leads to SIMOPS of some degree, and this paper discusses SIMOPS along with, more specifically, the challenges they provide to acoustic positioning. (author)

  5. Acoustic design by topology optimization

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Jensen, Jakob Søndergaard; Sigmund, Ole

    2008-01-01

    To bring down noise levels in human surroundings is an important issue and a method to reduce noise by means of topology optimization is presented here. The acoustic field is modeled by Helmholtz equation and the topology optimization method is based on continuous material interpolation functions...

  6. A numerical method for acoustic oscillations in tubes

    Science.gov (United States)

    Gary, John M.

    1988-01-01

    A numerical method to obtain the neutral curve for the onset of acoustic oscillations in a helium-filled tube is described. Such oscillations can cause a serious heat loss in the plumbing associated with liquid helium dewars. The problem is modelled by a second-order, ordinary differential eigenvalue problem for the pressure perturbation. The numerical method to find the eigenvalues and track the resulting points along the neutral curve is tailored to this problem. The results show that a tube with a uniform temperature gradient along it is much more stable than one where the temperature suddenly jumps from the cold to the hot value in the middle of the tube.

  7. Amorphization of Molecular Liquids of Pharmaceutical Drugs by Acoustic Levitation

    Directory of Open Access Journals (Sweden)

    C. J. Benmore

    2011-08-01

    Full Text Available It is demonstrated that acoustic levitation is able to produce amorphous forms from a variety of organic molecular compounds with different glass forming abilities. This can lead to enhanced solubility for pharmaceutical applications. High-energy x-ray experiments show that several viscous gels form from saturated pharmaceutical drug solutions after 10–20 min of levitation at room temperature, most of which can be frozen in solid form. Laser heating of ultrasonically levitated drugs can also result in the vitrification of molecular liquids, which is not attainable using conventional amorphization methods.

  8. Propagation of acoustic perturbations in a gas flow with dissipation

    Science.gov (United States)

    Zavershinskii, I. P.; Molevich, N. E.

    1992-10-01

    In an earlier study (Ingard and Singhal, 1973), it has been found that, in a nondissipating moving medium, an acoustic wave propagating from a source in the flow direction has a smaller amplitude than a wave moving against the flow. Here, it is demonstrated that consideration of dissipation phenomena, which are related to the shear and bulk viscosities and heat conductivity of a medium, leads to an additional anisotropy of the sound amplitude, whose sign is opposite to that obtained in the above mentioned study.

  9. 4th Pacific Rim Underwater Acoustics Conference

    CERN Document Server

    Xu, Wen; Cheng, Qianliu; Zhao, Hangfang

    2016-01-01

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

  10. An overview of Arctic Ocean acoustics

    Science.gov (United States)

    Hutt, Dan

    2012-11-01

    This paper presents a review of the underwater acoustics of the Arctic Ocean. It discusses the main features of the underwater acoustic environment and how they are so strongly affected by the presence of ice cover. The paper also discusses the history of Arctic Ocean acoustics research, how the motivation was originally military in character during the Cold War and how it changed to being driven by environmental considerations today. Originally, the physics of the Arctic Ocean was studied in order to predict its acoustic properties, and now acoustic techniques are used to help understand its physical environment.

  11. Robust acoustic wave manipulation of bubbly liquids

    Energy Technology Data Exchange (ETDEWEB)

    Gumerov, N. A., E-mail: gumerov@umiacs.umd.edu [Institute for Advanced Computer Studies, University of Maryland, College Park, Maryland 20742 (United States); Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Akhatov, I. S. [Center for Design, Manufacturing and Materials, Skolkovo Institute of Science and Technology, Moscow 143026 (Russian Federation); Ohl, C.-D. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Sametov, S. P. [Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Khazimullin, M. V. [Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076 (Russian Federation); Institute of Molecule and Crystal Physics, Ufa Research Center of Russian Academy of Sciences, Ufa 450054 (Russian Federation); Gonzalez-Avila, S. R. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)

    2016-03-28

    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.

  12. On architectural acoustic design using computer simulation

    DEFF Research Database (Denmark)

    Schmidt, Anne Marie Due; Kirkegaard, Poul Henning

    2004-01-01

    acoustic design process. The emphasis is put on the first three out of five phases in the working process of the architect and a case study is carried out in which each phase is represented by typical results ? as exemplified with reference to the design of Bagsværd Church by Jørn Utzon. The paper......Architectural acoustics design has in the past been based on simple design rules. However, with a growing complexity in architectural acoustics and the emergence of room acoustic simulation programmes with considerable potential, it is now possible to subjectively analyse and evaluate acoustic...... properties prior to the actual construction of a building. With the right tools applied, acoustic design can become an integral part of the architectural design process. The aim of this paper is to investigate the field of application that an acoustic simulation programme can have during an architectural...

  13. Handbook of Signal Processing in Acoustics

    CERN Document Server

    Havelock, David; Vorländer, Michael

    2009-01-01

    The Handbook of Signal Processing in Acoustics presents signal processing as it is practiced in the field of acoustics. The Handbook is organized by areas of acoustics, with recognized leaders coordinating the self-contained chapters of each section. It brings together a wide range of perspectives from over 100 authors to reveal the interdisciplinary nature of signal processing in acoustics. Success in acoustic applications often requires juggling both the acoustic and the signal processing parameters of the problem. This handbook brings the key issues from both into perspective and is complementary to other reference material on the two subjects. It is a unique resource for experts and practitioners alike to find new ideas and techniques within the diversity of signal processing in acoustics.

  14. On architectural acoustic design using computer simulation

    DEFF Research Database (Denmark)

    Schmidt, Anne Marie Due; Kirkegaard, Poul Henning

    2004-01-01

    Architectural acoustics design has in the past been based on simple design rules. However, with a growing complexity in architectural acoustics and the emergence of room acoustic simulation programmes with considerable potential, it is now possible to subjectively analyse and evaluate acoustic...... properties prior to the actual construction of a building. With the right tools applied, acoustic design can become an integral part of the architectural design process. The aim of this paper is to investigate the field of application that an acoustic simulation programme can have during an architectural...... acoustic design process. The emphasis is put on the first three out of five phases in the working process of the architect and a case study is carried out in which each phase is represented by typical results ? as exemplified with reference to the design of Bagsværd Church by Jørn Utzon. The paper...

  15. Magnetar heating

    CERN Document Server

    Beloborodov, Andrei M

    2016-01-01

    We examine four candidate mechanisms that could explain the high surface temperatures of magnetars. (1) Heat flux from the liquid core heated by ambipolar diffusion. It could sustain the observed surface luminosity $L_s\\approx 10^{35}$ erg s$^{-1}$ if core heating offsets neutrino cooling at a temperature $T_{\\rm core}>6\\times 10^8$ K. This scenario is viable if the core magnetic field exceeds $10^{16}$ G, the magnetar has mass $M10^{16}$ G varying on a 100 meter scale could provide $L_s\\approx 10^{35}$ erg s$^{-1}$. (4) Bombardment of the stellar surface by particles accelerated in the magnetosphere. This mechanism produces hot spots on magnetars. Observations of transient magnetars show evidence for external heating.

  16. Heat emergencies

    Science.gov (United States)

    ... death. The early symptoms of heat cramps include: Muscle cramps and pains that most often occur in the ... do if salt beverages are not available. For muscle cramps , give beverages as noted above and massage affected ...

  17. Low-temperature heat transfer in nanowires.

    Science.gov (United States)

    Glavin, B A

    2001-05-07

    A new regime of low-temperature heat transfer in suspended nanowires is predicted. It takes place when (i) only "acoustic" phonon modes of the wire are thermally populated and (ii) phonons are subject to the effective elastic scattering. Qualitatively, the main peculiarities of heat transfer originate due to the appearance of the flexural modes with high density of states in the wire phonon spectrum. They give rise to the T(1/2) temperature dependence of the wire thermal conductance. Experimental situations where the new regime is likely to be detected are discussed.

  18. Acoustic Characterization of Compact Jet Engine Simulator Units

    Science.gov (United States)

    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.

  19. Acoustically Driven Magnetized Target Fusion At General Fusion: An Overview

    Science.gov (United States)

    O'Shea, Peter; Laberge, M.; Donaldson, M.; Delage, M.; the Fusion Team, General

    2016-10-01

    Magnetized Target Fusion (MTF) involves compressing an initial magnetically confined plasma of about 1e23 m-3, 100eV, 7 Tesla, 20 cm radius, >100 μsec life with a 1000x volume compression in 100 microseconds. If near adiabatic compression is achieved, the final plasma of 1e26 m-3, 10keV, 700 Tesla, 2 cm radius, confined for 10 μsec would produce interesting fusion energy gain. General Fusion (GF) is developing an acoustic compression system using pneumatic pistons focusing a shock wave on the CT plasma in the center of a 3 m diameter sphere filled with liquid lead-lithium. Low cost driver, straightforward heat extraction, good tritium breeding ratio and excellent neutron protection could lead to a practical power plant. GF (65 employees) has an active plasma R&D program including both full scale and reduced scale plasma experiments and simulation of both. Although acoustic driven compression of full scale plasmas is the end goal, present compression studies use reduced scale plasmas and chemically accelerated Aluminum liners. We will review results from our plasma target development, motivate and review the results of dynamic compression field tests and briefly describe the work to date on the acoustic driver front.

  20. New acoustical technology of sound absorption based on reverse horn

    Science.gov (United States)

    Zhang, Yong Yan; Wu, Jiu Hui; Cao, Song Hua; Cao, Pei; Zhao, Zi Ting

    2016-12-01

    In this paper, a novel reverse horn’s sound-absorption mechanism and acoustic energy focusing mechanism for low-frequency broadband are presented. Due to the alternation of the reverse horn’s thickness, the amplitude of the acoustic pressure propagated in the structure changes, which results in growing energy focused in the edge and in the reverse horn’s tip when the characteristic length is equal to or less than a wavelength and the incident wave is compressed. There are two kinds of methods adopted to realize energy dissipation. On the one hand, sound-absorbing materials are added in incident direction in order to overcome the badness of the reverse horn’s absorption in high frequency and improve the overall high-frequency and low-frequency sound-absorption coefficients; on the other hand, adding mass and film in its tip could result in mechanical energy converting into heat energy due to the coupled vibration of mass and the film. Thus, the reverse horn with film in the tip could realize better sound absorption for low-frequency broadband. These excellent properties could have potential applications in the one-dimensional absorption wedge and for the control of acoustic wave.

  1. Propagation of magnetically guided acoustic shocks in the solar chromosphere

    Science.gov (United States)

    Foukal, P.; Smart, M.

    1981-01-01

    The propagation of a train of acoustic shocks guided by diverging magnetic fields through a static model of the solar chromospheric network and transition region is investigated. For initial flux densities of 1,000,000 ergs/sq cm/sec in the lower chromosphere, the local efficiency of acoustic transmission into the corona can be much higher than that calculated for a plane parallel atmosphere. Acoustic energy will tend to be deposited at higher chromospheric levels in diverging magnetic fields, and magnetic guiding may influence the temperature profile of the network and plages. The total flux that can be transmitted into the corona along such diverging fields is severely limited since the magnetic elements occupy a small fractional area of the photosphere and the transmission efficiency is a rapidly decreasing function of initial flux density. Diverging magnetic fields and a varying ratio of specific heats are not likely to allow high frequency shocks to dissipate high enough in a static atmosphere to contribute significantly to the coronal energy balance.

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

    DEFF Research Database (Denmark)

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

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

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

    DEFF Research Database (Denmark)

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

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

  4. Acoustic and thermal anomalies in a liquid-glass transition of racemic S(+)-R(-) ketoprofen

    Science.gov (United States)

    Shibata, Tomohiko; Takayama, Haruki; Kim, Tae Hyun; Kojima, Seiji

    2014-01-01

    Acoustic and thermal properties of pharmaceutical racemic S(+)-R(-) ketoprofen were investigated in wide temperature range including glassy, supercooled liquid and liquid states by Brillouin scattering and temperature modulated DSC. Sound velocity and acoustic attenuation exhibited clear changes at 265 K indicating a liquid-glass transition and showed the typical structural relaxation above Tg. The high value of the fragility index m = 71 was determined by the dispersion of the complex heat capacity. New relaxation map was suggested in combination with previous study of dielectric measurement.

  5. Acoustic effects analysis utilizing speckle pattern with fixed-particle Monte Carlo

    Science.gov (United States)

    Vakili, Ali; Hollmann, Joseph A.; Holt, R. Glynn; DiMarzio, Charles A.

    2016-03-01

    Optical imaging in a turbid medium is limited because of multiple scattering a photon undergoes while traveling through the medium. Therefore, optical imaging is unable to provide high resolution information deep in the medium. In the case of soft tissue, acoustic waves unlike light, can travel through the medium with negligible scattering. However, acoustic waves cannot provide medically relevant contrast as good as light. Hybrid solutions have been applied to use the benefits of both imaging methods. A focused acoustic wave generates a force inside an acoustically absorbing medium known as acoustic radiation force (ARF). ARF induces particle displacement within the medium. The amount of displacement is a function of mechanical properties of the medium and the applied force. To monitor the displacement induced by the ARF, speckle pattern analysis can be used. The speckle pattern is the result of interfering optical waves with different phases. As light travels through the medium, it undergoes several scattering events. Hence, it generates different scattering paths which depends on the location of the particles. Light waves that travel along these paths have different phases (different optical path lengths). ARF induces displacement to scatterers within the acoustic focal volume, and changes the optical path length. In addition, temperature rise due to conversion of absorbed acoustic energy to heat, changes the index of refraction and therefore, changes the optical path length of the scattering paths. The result is a change in the speckle pattern. Results suggest that the average change in the speckle pattern measures the displacement of particles and temperature rise within the acoustic wave focal area, hence can provide mechanical and thermal properties of the medium.

  6. High-overtone Bulk-Acoustic Resonator gravimetric sensitivity: towards wideband acoustic spectroscopy

    CERN Document Server

    Rabus, D; Ballandras, S; Baron, T; Lebrasseur, E; Carry, E

    2015-01-01

    In the context of direct detection sensors with compact dimensions, we investigate the gravimetric sensitivity of High-overtone Bulk Acoustic Resonators, through modeling of their acoustic characteristics and experiment. The high frequency characterizing such devices is expected to induce a significant effect when the acoustic field boundary conditions are modified by a thin adlayer. Furthermore, the multimode spectral characteristics is considered for wideband acoustic spectroscopy of the adlayer, once the gravimetric sensitivity dependence of the various overtones is established. Finally, means of improving the gravimetric sensitivity by confining the acoustic field in a low acoustic-impedance layer is theoretically established.

  7. Measurement of Heat Propagation in a Laser Produced Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gregori, G; Glenzer, S H; Knight, J; Niemann, C; Price, D; Froula, D H; Edwards, J; Town, R P J; Brantov, A; Bychenkov, V Y; Rozmus, W

    2003-08-22

    We present the observation of a nonlocal heat wave by measuring spatially and temporally resolved electron temperature profiles in a laser produced nitrogen plasma. Absolutely calibrated measurements have been performed by resolving the ion-acoustic wave spectra across the plasma volume with Thomson scattering. We find that the experimental electron temperature profiles disagree with flux-limited models, but are consistent with transport models that account for the nonlocal effects in heat conduction by fast electrons.

  8. APPLICATION OF DOMAIN DECOMPOSITION IN ACOUSTIC AND STRUCTURAL ACOUSTIC ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Conventional element based methods for modeling acoustic problems are limited to low-frequency applications due to the huge computational efforts. For high-frequency applications, probabilistic techniques, such as statistical energy analysis (SEA), are used. For mid-frequency range, currently no adequate and mature simulation methods exist. Recently, wave based method has been developed which is based on the indirect TREFFTZ approach and has shown to be able to tackle problems in the mid-frequency range. In contrast with the element based methods, no discretization is required. A sufficient, but not necessary, condition for convergence of this method is that the acoustic problem domain is convex. Non-convex domains have to be partitioned into a number of (convex) subdomains. At the interfaces between subdomains, specific coupling conditions have to be imposed. The considered two-dimensional coupled vibro-acoustic problem illustrates the beneficial convergence rate of the proposed wave based prediction technique with high accuracy. The results show the new technique can be applied up to much higher frequencies.

  9. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    Directory of Open Access Journals (Sweden)

    N. I. Polzikova

    2016-05-01

    Full Text Available We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW resonator (HBAR formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.

  10. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    Energy Technology Data Exchange (ETDEWEB)

    Polzikova, N. I., E-mail: polz@cplire.ru; Alekseev, S. G.; Pyataikin, I. I.; Kotelyanskii, I. M.; Luzanov, V. A.; Orlov, A. P. [Kotel’nikov Institute of Radio Engineering and Electronics of Russian Academy of Sciences, Mokhovaya 11, building 7, Moscow, 125009 (Russian Federation)

    2016-05-15

    We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW) resonator (HBAR) formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE) this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.

  11. Titanium honeycomb acoustic lining structural and thermal test report. [for acoustic tailpipe for JT8D engine

    Science.gov (United States)

    Joynes, D.; Balut, J. P.

    1974-01-01

    The results are presented of static, fatigue and thermal testing of titanium honeycomb acoustic panels representing the acoustic tailpipe for the Pratt and Whitney Aircraft JT8D Refan engine which is being studied for use on the Boeing 727-200 airplane. Test specimens represented the engine and tailpipe flange joints, the rail to which the thrust reverser is attached and shear specimens of the tailpipe honeycomb. Specimens were made in four different batches with variations in configuration, materials and processes in each. Static strength of all test specimens exceeded the design ultimate load requirements. Fatigue test results confirmed that aluminum brazed titanium, as used in the Refan tailpipe design, meets the fatigue durability objectives. Quality of welding was found to be critical to life, with substandard welding failing prematurely, whereas welding within the process specification exceeded the panel skin life. Initial fatigue testing used short grip length bolts which failed prematurely. These were replaced with longer bolts and subsequent testing demonstrated the required life. Thermal tests indicate that perforated skin acoustic honeycomb has approximately twice the heat transfer of solid skin honeycomb.

  12. Acoustic reflex and general anaesthesia.

    Science.gov (United States)

    Farkas, Z

    1983-01-01

    Infant and small children are not always able to cooperate in impedance measurements. For this reason it was decided, -in special cases, -to perform acoustic reflex examination under general anaesthesia. The first report on stapedius reflex and general anaesthesia was published by Mink et al. in 1981. Under the effect of Tiobutabarbital, Propanidid and Diazepam there is no reflex response. Acoustic reflex can be elicited with Ketamin-hydrochlorid and Alphaxalone-alphadolone acetate narcosis. The reflex threshold remains unchanged and the amplitude of muscle contraction is somewhat increased. The method was used: 1. to assess the type and degree of hearing loss in children with cleft palate and/or lip prior to surgery. 2. to exclude neuromuscular disorders with indication of pharyngoplasties. 3. to quantify hearing level in children--mostly multiply handicapped--with retarded speech development. The results of Behavioral Observation and Impedance Audiometry are discussed and evaluated.

  13. Oscillating nonlinear acoustic shock waves

    DEFF Research Database (Denmark)

    Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth

    2016-01-01

    We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...... that at resonance a stationary state arise consisting of multiple oscillating shock waves. Off resonance driving leads to a nearly linear oscillating ground state but superimposed by bursts of a fast oscillating shock wave. Based on a travelling wave ansatz for the fluid velocity potential with an added 2'nd order...... polynomial in the space and time variables, we find analytical approximations to the observed single shock waves in an infinitely long tube. Using perturbation theory for the driven acoustic system approximative analytical solutions for the off resonant case are determined....

  14. Acoustic modes in fluid networks

    Science.gov (United States)

    Michalopoulos, C. D.; Clark, Robert W., Jr.; Doiron, Harold H.

    Pressure and flow rate eigenvalue problems for one-dimensional flow of a fluid in a network of pipes are derived from the familiar transmission line equations. These equations are linearized by assuming small velocity and pressure oscillations about mean flow conditions. It is shown that the flow rate eigenvalues are the same as the pressure eigenvalues and the relationship between line pressure modes and flow rate modes is established. A volume at the end of each branch is employed which allows any combination of boundary conditions, from open to closed, to be used. The Jacobi iterative method is used to compute undamped natural frequencies and associated pressure/flow modes. Several numerical examples are presented which include acoustic modes for the Helium Supply System of the Space Shuttle Orbiter Main Propulsion System. It should be noted that the method presented herein can be applied to any one-dimensional acoustic system involving an arbitrary number of branches.

  15. Cooperative OFDM underwater acoustic communications

    CERN Document Server

    Cheng, Xilin; Cheng, Xiang

    2016-01-01

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

  16. [Acoustic information in snoring noises].

    Science.gov (United States)

    Janott, C; Schuller, B; Heiser, C

    2017-02-01

    More than one third of all people snore regularly. Snoring is a common accompaniment of obstructive sleep apnea (OSA) and is often disruptive for the bed partner. This work gives an overview of the history of and state of research on acoustic analysis of snoring for classification of OSA severity, detection of obstructive events, measurement of annoyance, and identification of the sound excitation location. Based on these objectives, searches were conducted in the literature databases PubMed and IEEE Xplore. Publications dealing with the respective objectives according to title and abstract were selected from the search results. A total of 48 publications concerning the above objectives were considered. The limiting factor of many studies is the small number of subjects upon which the analyses are based. Recent research findings show promising results, such that acoustic analysis may find a place in the framework of sleep diagnostics, thus supplementing the recognized standard methods.

  17. Uncertainty analysis in acoustic investigations

    OpenAIRE

    2013-01-01

    The problem of uncertainty assessment in acoustic investigations is presented in the hereby paper. The aspect of the uncertainty asymmetry in processing of data obtained in the measuring test of sound levels, determined in decibels, was sketched. On the basis of the analysis of data obtained in the continuous monitoring of road traffic noise in Krakow typical probability distributions for a day, evening and night were determined. The method of the uncertainty assessment based on the propagati...

  18. Acoustical characterization of portuguese libraries

    OpenAIRE

    António Pedro Oliveira de Carvalho; António Eduardo Batista da Costa

    2010-01-01

    This paper presents the acoustical characterization of the main reading room of 28 public li-braries in Portugal. In situ measurements were held regarding the interior sound pressure lev-els (background noise, with and without the HVAC equipment working), the Noise Criteria and Noise Rating values (NC/NR), the objective speech intelligibility using the Rapid Speech Transmission Index (RASTI) and Reverberation Time (125 to 4k Hz). Two groups of librar-ies were formed (Classic and Modern librar...

  19. Underwater Acoustic Beacon Location System

    Science.gov (United States)

    2016-12-23

    transpose operator is a standard operator in linear or matrix algebra . The transpose operator converts the row vector   T aaaa z,y,x=P to a column...February 2017 The below identified patent application is available for licensing. Requests for information should be addressed to...300087 1 of 31 UNDERWATER ACOUSTIC BEACON LOCATION SYSTEM [0001] The present application claims the benefit of United States Provisional

  20. Acoustic Propagation Modeling Using MATLAB

    Science.gov (United States)

    1993-09-01

    Acoustic propagation, transient waves, transfer function, linear systems theory 16. PRICE CODE 17. SECURITY CLASSIFICATION 13. SECURITY CLASSIFICATION 1...method of diffraction prediction. This report describes an ap- proach based on linear systems theory and the Fourier transform. The goal was to achieve a...differed by the use of linear systems theory . Linear systems theory revealed the importance of the total impulse response and its equivalence to the

  1. Annual Report for Ocean Acoustics

    Science.gov (United States)

    2013-09-30

    feeding , diving) and social boundings (mum- calf , mum- calf and associated adult, adult-adult). Moreover, by cross- correlating the transmitted and received...such approach. In order to do so, we make use of existing numerical acoustic propagation methods, e.g. Vertex, feed these methods with different...transmission occurs. We also consider the cost of feeding this channel state information back and develop a controller that minimizes the number of both

  2. APL - North Pacific Acoustic Laboratory

    Science.gov (United States)

    2015-03-04

    Flatté’s statistical acoustic code to Mike Porter at HLS Research for inclusion in the OALIB website. PUBLICATIONS Andrew, Rex K., James A...show the MCPE confidence intervals and curves with diamonds show confidence intervals on the measured values. Diamonds indicate the depths at which...left, except that only depths from 800 to 1400 m are shown. The diamond -shaped symbols show the arrival depth and corresponding intensity of rays with

  3. Acoustic telemetry and fisheries management

    Science.gov (United States)

    Crossin, Glenn T.; Heupel, Michelle R.; Holbrook, Christopher; Hussey, Nigel E.; Lowerre-Barbieri, Susan K; Nguyen, Vivian M.; Raby, Graham D.; Cooke, Steven J.

    2017-01-01

    This paper reviews the use of acoustic telemetry as a tool for addressing issues in fisheries management, and serves as the lead to the special Feature Issue of Ecological Applications titled “Acoustic Telemetry and Fisheries Management”. Specifically, we provide an overview of the ways in which acoustic telemetry can be used to inform issues central to the ecology, conservation, and management of exploited and/or imperiled fish species. Despite great strides in this area in recent years, there are comparatively few examples where data have been applied directly to influence fisheries management and policy. We review the literature on this issue, identify the strengths and weaknesses of work done to date, and highlight knowledge gaps and difficulties in applying empirical fish telemetry studies to fisheries policy and practice. We then highlight the key areas of management and policy addressed, as well as the challenges that needed to be overcome to do this. We conclude with a set of recommendations about how researchers can, in consultation with stock assessment scientists and managers, formulate testable scientific questions to address and design future studies to generate data that can be used in a meaningful way by fisheries management and conservation practitioners. We also urge the involvement of relevant stakeholders (managers, fishers, conservation societies, etc.) early on in the process (i.e. in the co-creation of research projects), so that all priority questions and issues can be addressed effectively.

  4. Acoustic measurements of models of military style supersonic nozzle jets

    Directory of Open Access Journals (Sweden)

    Ching-Wen Kuo

    2014-02-01

    Full Text Available Modern military aircraft jet engines are designed with variable-geometry nozzles to provide optimal thrust in different operating conditions, depending on the flight envelope. However, acoustic measurements for such nozzles are scarce, due to the cost involved in making full-scale measurements and the lack of details about the exact geometries of these nozzles. Thus the present effort at Pennsylvania State University (PSU in partnership with GE Aviation and the NASA Glenn Research Center is aiming to study and characterize the acoustic field produced by supersonic jets issuing from converging-diverging military style nozzles, and to identify and test promising noise reduction techniques. An equally important objective is to develop methodology for using data obtained from small- and moderate-scale experiments to reliably predict the full-scale engine noise. The experimental results presented show reasonable agreement between small-scale and medium-scale jets, as well as between heated jets and heat-simulated ones.

  5. Acoustic measurements of models of military style supersonic nozzle jets

    Institute of Scientific and Technical Information of China (English)

    Ching-Wen Kuo; Jérémy Veltin; Dennis K. McLaughlin

    2014-01-01

    Modern military aircraft jet engines are designed with variable-geometry nozzles to provide optimal thrust in different operating conditions, depending on the flight envelope. How-ever, acoustic measurements for such nozzles are scarce, due to the cost involved in making full-scale measurements and the lack of details about the exact geometries of these nozzles. Thus the present effort at Pennsylvania State University (PSU) in partnership with GE Aviation and the NASA Glenn Research Center is aiming to study and characterize the acoustic field produced by supersonic jets issuing from converging-diverging military style nozzles, and to identify and test promising noise reduction techniques. An equally important objective is to develop methodology for using data obtained from small-and moderate-scale experiments to reliably predict the full-scale engine noise. The experimental results presented show reasonable agreement between small-scale and medium-scale jets, as well as between heated jets and heat-simulated ones.

  6. Vibro-acoustic analysis of the acoustic-structure interaction of flexible structure due to acoustic excitation

    Science.gov (United States)

    Djojodihardjo, Harijono

    2015-03-01

    The application of BE-FE acoustic-structure interaction on a structure subject to acoustic load is elaborated using the boundary element-finite element acoustic structural coupling and the utilization of the computational scheme developed earlier. The plausibility of the numerical treatment is investigated and validated through application to generic cases. The analysis carried out in the work is intended to serve as a baseline in the analysis of acoustic structure interaction for lightweight structures. Results obtained thus far exhibit the robustness of the method developed.

  7. Heat transfer

    CERN Document Server

    Holman, J P

    2010-01-01

    As one of the most popular heat transfer texts, Jack Holman's "Heat Transfer" is noted for its clarity, accessible approach, and inclusion of many examples and problem sets. The new tenth edition retains the straight-forward, to-the-point writing style while covering both analytical and empirical approaches to the subject. Throughout the book, emphasis is placed on physical understanding while, at the same time, relying on meaningful experimental data in those situations that do not permit a simple analytical solution. New examples and templates provide students with updated resources for computer-numerical solutions.

  8. Measuring Acoustic Wave Transit Time in Furnace Based on Active Acoustic Source Signal

    Institute of Scientific and Technical Information of China (English)

    Zhen Luo; Feng Tian; Xiao-Ping Sun

    2007-01-01

    Accurate measurement of transit time for acoustic wave between two sensors installed on two sides of a furnace is a key to implementing the temperature field measurement technique based on acoustical method. A new method for measuring transit time of acoustic wave based on active acoustic source signal is proposed in this paper, which includes the followings: the time when the acoustic source signal arrives at the two sensors is measured first; then, the difference of two arriving time arguments is computed, thereby we get the transit time of the acoustic wave between two sensors installed on the two sides of the furnace. Avoiding the restriction on acoustic source signal and background noise, the new method can get the transit time of acoustic wave with higher precision and stronger ability of resisting noise interference.

  9. Heat-Related Illnesses

    Medline Plus

    Full Text Available ... for signs of heat stroke or exhaustion. Heat Stroke and Exhaustion Symptoms of early heat exhaustion symptoms ... heavy sweating; nausea; and giddiness. Symptoms of heat stroke (late stage of heat illness) include flushed, hot, ...

  10. Heat-Related Illnesses

    Medline Plus

    Full Text Available ... for signs of heat stroke or exhaustion. Heat Stroke and Exhaustion Symptoms of early heat exhaustion symptoms ... heavy sweating; nausea; and giddiness. Symptoms of heat stroke (late stage of heat illness) include flushed, hot, ...

  11. Product Sound: Acoustically pleasant motor drives

    DEFF Research Database (Denmark)

    Mathe, Laszlo

    The work in this thesis is focused on the acoustic noise generated by electrical motors driven by a pulse width modulated (PWM) power electronic inverter. In a usual inverter based electrical drive, the modulation uses fixed switching frequency; that introduces a set of harmonics in the acoustic...... is to ameliorate this whistling acoustic noise, while maintaining the efficiency of the drive. The first chapter of the report is an introductory chapter where the motivation, objectives, limitations and an overview on electrical motor acoustics are presented. A list of main contributions of this PhD project...... the acoustic measurements of the ventilation system using various modulation techniques. A new trend in HVAC is to use permanent magnet synchronous motor (PMSM) instead of the asynchronous motor, in order to increase the efficiency of the electrical drive. In this chapter, the acoustic performance of the two...

  12. Integration of Acoustic Detection Equipment into ANTARES

    CERN Document Server

    Lahmann, R; Graf, K; Hoessl, J; Kappes, A; Karg, T; Katz, U; Naumann, C; Salomon, K

    2005-01-01

    The ANTARES group at the University of Erlangen is working towards the integration of a set of acoustic sensors into the ANTARES Neutrino Telescope. With this setup, tests of acoustic particle detection methods and background studies shall be performed. The ANTARES Neutrino Telescope, which is currently being constructed in the Mediterranean Sea, will be equipped with the infrastructure to accommodate a 3-dimensional array of photomultipliers for the detection of Cherenkov light. Within this infrastructure, the required resources for acoustic sensors are available: Bandwidth for the transmission of the acoustic data to the shore, electrical power for the off-shore electronics and physical space to install the acoustic sensors and to route the connecting cables (transmitting signals and power) into the electronics containers. It will be explained how the integration will be performed with minimal modifications of the existing ANTARES design and which setup is foreseen for the acquisition of the acoustic data.

  13. Acoustic wave science realized by metamaterials.

    Science.gov (United States)

    Lee, Dongwoo; Nguyen, Duc Minh; Rho, Junsuk

    2017-01-01

    Artificially structured materials with unit cells at sub-wavelength scale, known as metamaterials, have been widely used to precisely control and manipulate waves thanks to their unconventional properties which cannot be found in nature. In fact, the field of acoustic metamaterials has been much developed over the past 15 years and still keeps developing. Here, we present a topical review of metamaterials in acoustic wave science. Particular attention is given to fundamental principles of acoustic metamaterials for realizing the extraordinary acoustic properties such as negative, near-zero and approaching-infinity parameters. Realization of acoustic cloaking phenomenon which is invisible from incident sound waves is also introduced by various approaches. Finally, acoustic lenses are discussed not only for sub-diffraction imaging but also for applications based on gradient index (GRIN) lens.

  14. Acoustic levitation of a large solid sphere

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Marco A. B., E-mail: marcobrizzotti@gmail.com [Institute of Physics, University of São Paulo, São Paulo 05508-090 (Brazil); Bernassau, Anne L. [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Adamowski, Julio C. [Department of Mechatronics and Mechanical Systems Engineering, Escola Politécnica, University of São Paulo, São Paulo 05508-030 (Brazil)

    2016-07-25

    We demonstrate that acoustic levitation can levitate spherical objects much larger than the acoustic wavelength in air. The acoustic levitation of an expanded polystyrene sphere of 50 mm in diameter, corresponding to 3.6 times the wavelength, is achieved by using three 25 kHz ultrasonic transducers arranged in a tripod fashion. In this configuration, a standing wave is created between the transducers and the sphere. The axial acoustic radiation force generated by each transducer on the sphere was modeled numerically as a function of the distance between the sphere and the transducer. The theoretical acoustic radiation force was verified experimentally in a setup consisting of an electronic scale and an ultrasonic transducer mounted on a motorized linear stage. The comparison between the numerical and experimental acoustic radiation forces presents a good agreement.

  15. High-sensitivity fiber optic acoustic sensors

    Science.gov (United States)

    Lu, Ping; Liu, Deming; Liao, Hao

    2016-11-01

    Due to the overwhelming advantages compared with traditional electronicsensors, fiber-optic acoustic sensors have arisen enormous interest in multiple disciplines. In this paper we present the recent research achievements of our group on fiber-optic acoustic sensors. The main point of our research is high sensitivity interferometric acoustic sensors, including Michelson, Sagnac, and Fabry-Pérot interferometers. In addition, some advanced technologies have been proposed for acoustic or acoustic pressure sensing such as single-mode/multimode fiber coupler, dual FBGs and multi-longitudinal mode fiber laser based acoustic sensors. Moreover, our attention we have also been paid on signal demodulation schemes. The intensity-based quadrature point (Q-point) demodulation, two-wavelength quadrature demodulation and symmetric 3×3 coupler methodare discussed and compared in this paper.

  16. Acoustic communication in plant-animal interactions.

    Science.gov (United States)

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

    2016-08-01

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

  17. Acoustic levitation of a large solid sphere

    Science.gov (United States)

    Andrade, Marco A. B.; Bernassau, Anne L.; Adamowski, Julio C.

    2016-07-01

    We demonstrate that acoustic levitation can levitate spherical objects much larger than the acoustic wavelength in air. The acoustic levitation of an expanded polystyrene sphere of 50 mm in diameter, corresponding to 3.6 times the wavelength, is achieved by using three 25 kHz ultrasonic transducers arranged in a tripod fashion. In this configuration, a standing wave is created between the transducers and the sphere. The axial acoustic radiation force generated by each transducer on the sphere was modeled numerically as a function of the distance between the sphere and the transducer. The theoretical acoustic radiation force was verified experimentally in a setup consisting of an electronic scale and an ultrasonic transducer mounted on a motorized linear stage. The comparison between the numerical and experimental acoustic radiation forces presents a good agreement.

  18. Coupling between plate vibration and acoustic radiation

    Science.gov (United States)

    Frendi, Abdelkader; Maestrello, Lucio; Bayliss, Alvin

    1993-01-01

    A detailed numerical investigation of the coupling between the vibration of a flexible plate and the acoustic radiation is performed. The nonlinear Euler equations are used to describe the acoustic fluid while the nonlinear plate equation is used to describe the plate vibration. Linear, nonlinear, and quasi-periodic or chaotic vibrations and the resultant acoustic radiation are analyzed. We find that for the linear plate response, acoustic coupling is negligible. However, for the nonlinear and chaotic responses, acoustic coupling has a significant effect on the vibration level as the loading increases. The radiated pressure from a plate undergoing nonlinear or chaotic vibrations is found to propagate nonlinearly into the far field. However, the nonlinearity due to wave propagation is much weaker than that due to the plate vibrations. As the acoustic wave propagates into the far field, the relative difference in level between the fundamental and its harmonics and subharmonics decreases with distance.

  19. Acoustic emission characterization of fracture toughness for fiber reinforced ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Hui, E-mail: phdhuimei@yahoo.com [Science and Technology on Thermostructure Composite Materials Laboratory, Northwestern Polytechnical University, Xi' an Shaanxi 710072 (China); Sun, Yuyao; Zhang, Lidong; Wang, Hongqin; Cheng, Laifei [Science and Technology on Thermostructure Composite Materials Laboratory, Northwestern Polytechnical University, Xi' an Shaanxi 710072 (China)

    2013-01-10

    The fracture toughness of a carbon fiber reinforced silicon carbide composite was investigated relating to classical critical stress intensity factor K{sub IC}, work of fracture, and acoustic emission energy. The K{sub IC} was obtained by the single edge notch beam method and the work of fracture was calculated using the featured area under the load-displacement curves. The K{sub IC}, work of fracture, and acoustic emission energy were compared for the composites before and after heat treatment and then analyzed associated with toughening microstructures of fiber pullout. It indicates that the work of fracture and acoustic emission energy can be more suitable to reflect the toughness rather than the traditional K{sub IC}, which has certain limitation for the fracture toughness characterization of the crack tolerant fiber ceramic composites.

  20. The frequency and damping of ion acoustic waves in collisional and collisionless two-species plasma

    Energy Technology Data Exchange (ETDEWEB)

    Berger, R L; Valeo, E J

    2004-07-15

    The dispersion properties of ion acoustic waves (IAW) are sensitive to the strength of ion-ion collisions in multi-species plasma in which the different species usually have differing charge-to-mass ratios. The modification of the frequency and damping of the fast and slow acoustic modes in a plasma composed of light (low Z) and heavy (high Z) ions is considered. In the fluid limit where the light ion scattering mean free path, {lambda}{sub th} is smaller than the acoustic wavelength, {lambda} = 2{pi}/k, the interspecies friction and heat flow carried by the light ions scattering from the heavy ions causes the damping. In the collisionless limit, k{lambda}{sub lh} >> 1, Landau damping by the light ions provides the dissipation. In the intermediate regime when k{lambda}{sub lh} {approx} 1, the damping is at least as large as the sum of the collisional and Landau damping.

  1. The Frequency and Damping of Ion Acoustic Waves in Collisional and Collisionless Two-species Plasma

    Energy Technology Data Exchange (ETDEWEB)

    R.L. Berger; E.J. Valeo

    2004-08-18

    The dispersion properties of ion acoustic waves (IAW) are sensitive to the strength of ion-ion collisions in multi-species plasma in which the different species usually have differing charge-to-mass ratios. The modification of the frequency and damping of the fast and slow acoustic modes in a plasma composed of light (low Z) and heavy (high Z) ions is considered. In the fluid limit where the light ion scattering mean free path, {lambda}{sub th} is smaller than the acoustic wavelength, {lambda} = 2{pi}/k, the interspecies friction and heat flow carried by the light ions scattering from the heavy ions causes the damping. In the collisionless limit, k{lambda}{sub th} >> 1, Landau damping by the light ions provides the dissipation. In the intermediate regime when k{lambda}{sub th} {approx} 1, the damping is at least as large as the sum of the collisional and Landau damping.

  2. Foam/Aerogel Composite Materials for Thermal and Acoustic Insulation and Cryogen Storage

    Science.gov (United States)

    Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Weiser, Erik S. (Inventor); Sass, Jared P. (Inventor)

    2011-01-01

    The invention involves composite materials containing a polymer foam and an aerogel. The composite materials have improved thermal insulation ability, good acoustic insulation, and excellent physical mechanical properties. The composite materials can be used, for instance, for heat and acoustic insulation on aircraft, spacecraft, and maritime ships in place of currently used foam panels and other foam products. The materials of the invention can also be used in building construction with their combination of light weight, strength, elasticity, ability to be formed into desired shapes, and superior thermal and acoustic insulation power. The materials have also been found to have utility for storage of cryogens. A cryogenic liquid or gas, such as N.sub.2 or H.sub.2, adsorbs to the surfaces in aerogel particles. Thus, another embodiment of the invention provides a storage vessel for a cryogen.

  3. Capturing molecular multimode relaxation processes in excitable gases based on decomposition of acoustic relaxation spectra

    Science.gov (United States)

    Zhu, Ming; Liu, Tingting; Wang, Shu; Zhang, Kesheng

    2017-08-01

    Existing two-frequency reconstructive methods can only capture primary (single) molecular relaxation processes in excitable gases. In this paper, we present a reconstructive method based on the novel decomposition of frequency-dependent acoustic relaxation spectra to capture the entire molecular multimode relaxation process. This decomposition of acoustic relaxation spectra is developed from the frequency-dependent effective specific heat, indicating that a multi-relaxation process is the sum of the interior single-relaxation processes. Based on this decomposition, we can reconstruct the entire multi-relaxation process by capturing the relaxation times and relaxation strengths of N interior single-relaxation processes, using the measurements of acoustic absorption and sound speed at 2N frequencies. Experimental data for the gas mixtures CO2-N2 and CO2-O2 validate our decomposition and reconstruction approach.

  4. Analysis of Acoustic Emission Signal by Fractal Theory in Aluminum Alloy Spot Welding

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The relation between acoustic emission signal and nugget during aluminum alloy spot welding was investigated in order to evaluate spot welding quality. Due to the nonlinearity of the signals, fractal theory was utilized to quantitatively describe the characteristics of the signals instead of classical Euclidean geometry which cannot describe the acoustic emission signal accurately. Through experiments and computing, the box counting dimension is found distinct from other acoustic emission signals and is a better approach to discriminating weld nugget stages. Results show that fractal dimensions increase from 1.51 to 1.78,and they are related to nugget areas added from non-fusion to over-heated nugget.And the box counting dimension can effectively evaluate the quality of the nugget in the spot welding and can be applied with current, displace, and other spot welding parameters.

  5. Probing thermomechanics at the nanoscale: impulsively excited pseudosurface acoustic waves in hypersonic phononic crystals.

    Science.gov (United States)

    Nardi, Damiano; Travagliati, Marco; Siemens, Mark E; Li, Qing; Murnane, Margaret M; Kapteyn, Henry C; Ferrini, Gabriele; Parmigiani, Fulvio; Banfi, Francesco

    2011-10-12

    High-frequency surface acoustic waves can be generated by ultrafast laser excitation of nanoscale patterned surfaces. Here we study this phenomenon in the hypersonic frequency limit. By modeling the thermomechanics from first-principles, we calculate the system's initial heat-driven impulsive response and follow its time evolution. A scheme is introduced to quantitatively access frequencies and lifetimes of the composite system's excited eigenmodes. A spectral decomposition of the calculated response on the eigemodes of the system reveals asymmetric resonances that result from the coupling between surface and bulk acoustic modes. This finding allows evaluation of impulsively excited pseudosurface acoustic wave frequencies and lifetimes and expands our understanding of the scattering of surface waves in mesoscale metamaterials. The model is successfully benchmarked against time-resolved optical diffraction measurements performed on one-dimensional and two-dimensional surface phononic crystals, probed using light at extreme ultraviolet and near-infrared wavelengths.

  6. Vortex-acoustic lock-on in bluff-body and backward-facing step combustors

    Indian Academy of Sciences (India)

    S R Chakravarthy; R Sivakumar; O J Shreenivasan

    2007-02-01

    Experimental data on acoustic pressure measurements obtained over a wide range of conditions is reported for two simple geometries that are commonly studied for their combustion dynamics behaviour. These geometries are the confined bluff-body and the confined backward-facing steps. The data indicate regimes of flow-acoustic lock-on that signifies the onset of combustion instability, marked by the excitation of high-amplitude discrete tones of sound in the combustor. The highspeed chemiluminescence imaging of the combustion zone indicates heat-release-rate fluctuations occurring at the same frequencies as observed in the acoustic spectra. Attention is then devoted to the data obtained under cold-flow conditions to illustrate distinctly different behaviour than when combustion instability occurs, contrary to the commonly held view that the combustion process does not alter the underlying fluid mechanical processes under low-Mach number conditions.

  7. Detection of ultra high energy neutrinos with an underwater very large volume array of acoustic sensors: A simulation study

    CERN Document Server

    Karg, T

    2006-01-01

    This thesis investigates the detection of ultra high energy (E > 1 EeV) cosmic neutrinos using acoustic sensors immersed in water. The method is based on the thermoacoustic model describing the production of microsecond bipolar acoustic pulses by neutrino-induced particle cascades. These cascades locally heat the medium which leads to rapid expansion and a short sonic pulse detectable in water with hydrophones over distances of several kilometres. This makes acoustic detection an approach complementary to todays optical Cerenkov and radio Cerenkov detectors, and could help to reduce the respective systematic uncertainties. In this work a complete simulation / reconstruction chain for a submarine acoustic neutrino telescope is developed, and the sensitivity of such a detector to a diffuse flux of ultra highenergy cosmic neutrinos is estimated.

  8. North Pacific Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea

    Science.gov (United States)

    2016-06-21

    and Yuen, M. Y. (2015). "Multipurpose acoustic networks in the Integrated Arctic Ocean Observing System," Arctic 68, 11-27. 2. Publications...the "Special Issue on Deep-water Ocean Acoustics" in the Journal of the Acoustical Society of America (Vol. 134, No . 4, Pt. 2 of 2 , October20 13...15. SUBJECT TERMS ocean acoustics, deep water acousti c propagati on 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF a. REPORT b. ABSTRACT c

  9. Experimental Acoustic Evaluation of an Auditorium

    Directory of Open Access Journals (Sweden)

    Marina Dana Ţopa

    2012-01-01

    Full Text Available The paper presents a case history: the acoustical analysis of a rectangular auditorium. The following acoustical parameters were evaluated: early decay time, reverberation time, clarity, definition, and center time. The excitation signal was linear sweep sine and additional analysis was carried out: peak-to-noise ratio, reverberation time for empty and occupied room, standard deviation of acoustical parameters, diffusion, and just noticeable differences analysis. Conclusions about room’s destination and modeling were drawn in the end.

  10. Acoustic resonance phase locked photoacoustic spectrometer

    Science.gov (United States)

    Pilgrim, Jeffrey S.; Bomse, David S.; Silver, Joel A.

    2003-08-19

    A photoacoustic spectroscopy method and apparatus for maintaining an acoustic source frequency on a sample cell resonance frequency comprising: providing an acoustic source to the sample cell to generate a photoacoustic signal, the acoustic source having a source frequency; continuously measuring detection phase of the photoacoustic signal with respect to source frequency or a harmonic thereof; and employing the measured detection phase to provide magnitude and direction for correcting the source frequency to the resonance frequency.

  11. Acoustic resonance frequency locked photoacoustic spectrometer

    Science.gov (United States)

    Pilgrim, Jeffrey S.; Bomse, David S.; Silver, Joel A.

    2003-09-09

    A photoacoustic spectroscopy method and apparatus for maintaining an acoustic source frequency on a sample cell resonance frequency comprising: providing an acoustic source to the sample cell, the acoustic source having a source frequency; repeatedly and continuously sweeping the source frequency across the resonance frequency at a sweep rate; and employing an odd-harmonic of the source frequency sweep rate to maintain the source frequency sweep centered on the resonance frequency.

  12. Outdoor Synthetic Aperture Acoustic Ground Target Measurements

    Science.gov (United States)

    2010-04-19

    1341 (2003). [11] C. A. Dimarzio, T. Shi, F. J. Blonigen et al., “ Laser -Induced Acoustic Landmine Detection,” The Journal Of The Acoustical Society...High Frequency A/S Coupling For Ap Buried Landmine Detection Using Laser Doppler Vibrometers,” Proc. SPIE 5415(1), 35-41 (2004). [16] Bishop, S... Dolphin Echolocation Clicks For Target Discrimination,” The Journal Of The Acoustical Society Of America 124(1), 657-666 (2008). [20] Y. Nakamura

  13. Memory-Effect on Acoustic Cavitation

    OpenAIRE

    Yavaṣ, Oğuz; Leiderer, Paul; Park, Hee K.; Grigoropoulos, Costas P.; Poon, Chie C.; Tam, Andrew C.

    1994-01-01

    The formation of bubbles at a liquid-solid interface due to acoustic cavitation depends particularly on the preconditions of the interface. Here, it wiIl be shown that following laser-induced bubble formation at the interface the acoustic cavitation efficiency is strongly enhanced. Optical reflectance measurements reveal that this observed enhancement of acoustic cavitation due to preceding laser-induced bubble formation, which could be termed as memory effect, decays in a few hundred microse...

  14. Detecting the Nonlinearity of Fish Acoustic Signals

    Institute of Scientific and Technical Information of China (English)

    REN Xinmin; YIN Li

    2006-01-01

    This paper discusses the nonlinearity of fish acoustic signals by using the surrogate data method.We compare the difference of three test statistics - time-irreversibility Trey, correlation dimension D2 and auto mutual information function Ⅰbetween the original data and the surrogate data.We come to the conclusion that there exists nonlinearity in the fish acoustic signals and there exist deterministic nonlinear components; therefore nonlinear dynamic theory can be used to analyze fish acoustic signals.

  15. Acoustic 3D imaging of dental structures

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, D.K. [Lawrence Livermore National Lab., CA (United States); Hume, W.R. [California Univ., Los Angeles, CA (United States); Douglass, G.D. [California Univ., San Francisco, CA (United States)

    1997-02-01

    Our goals for the first year of this three dimensional electodynamic imaging project was to determine how to combine flexible, individual addressable; preprocessing of array source signals; spectral extrapolation or received signals; acoustic tomography codes; and acoustic propagation modeling code. We investigated flexible, individually addressable acoustic array material to find the best match in power, sensitivity and cost and settled on PVDF sheet arrays and 3-1 composite material.

  16. Acoustic Casimir Pressure for Arbitrary Media

    CERN Document Server

    Barcenas, J; Esquivel-Sirvent, R

    2004-01-01

    In this paper we derive a general expression for the acoustic Casimir pressure between two parallel slabs made of arbitrary materials and whose acoustic reflection coefficients are not equal. The formalism is based on the calculation of the local density of modes using a Green's function approach. The results for the Casimir acoustic pressure are generalized to a sphere/plate configuration using the proximity theorem

  17. Infrared heating

    Science.gov (United States)

    IR heating was first industrially used in the 1930s for automotive curing applications and rapidly became a widely applied technology in the manufacturing industry. Contrarily, a slower pace in the development of IR technologies for processing foods and agricultural products was observed, due to lim...

  18. Characteristic of Secondary Flow Caused by Local Density Change in Standing Acoustic Fields

    Science.gov (United States)

    Tonsho, Kazuyuki; Hirosawa, Takuya; Kusakawa, Hiroshi; Kuwahara, Takuo; Tanabe, Mitsuaki

    Secondary flow is a flow which is caused by the interference between standing acoustic fields and local density change. The behavior of the secondary flow depends on the location of the given local density change in the standing acoustic fields. When the density change is given at the middle of a velocity node and the neighboring velocity anti-node (middle point) or when it is given at the velocity anti-node in standing acoustic fields, the secondary flow shows particular behavior. Characteristic of the secondary flow at the two positions was predicted by numerical simulations. It was examined from these simulations whether the driving mechanism of the flow can be explained by the kind of acoustic radiation force that has been proposed so far. The predicted secondary flow was verified by experiments. For both the simulations and experiments, the standing acoustic fields generated in a cylinder are employed. In the experiments, the acoustic fields are generated by two loud speakers that are vibrated in same phase in a chamber. The employed resonance frequency is about 1000 Hz. The chamber is filled with air of room temperature and atmospheric pressure. In the numerical simulations and experiments, the local density change is given by heating or cooling. Because the secondary flow is influenced by buoyancy, the numerical simulations were done without taking gravity force into account and a part of the experiments were done by the microgravity condition using a drop tower. As a result of the simulations, at the middle point, the heated air was blown toward the node and the cooled air was blown toward the anti-node. It is clarified that the secondary flow is driven by the expected kind of acoustic radiation force. At the anti-node, both the heated and cooled air expands perpendicular to the traveling direction of the sound wave. The driving mechanism of the secondary flow can not be explained by the acoustic radiation force, and a detailed analysis is done. Through the

  19. Theory of Acoustic Raman Modes in Proteins

    Science.gov (United States)

    DeWolf, Timothy; Gordon, Reuven

    2016-09-01

    We present a theoretical analysis that associates the resonances of extraordinary acoustic Raman (EAR) spectroscopy [Wheaton et al., Nat. Photonics 9, 68 (2015)] with the collective modes of proteins. The theory uses the anisotropic elastic network model to find the protein acoustic modes, and calculates Raman intensity by treating the protein as a polarizable ellipsoid. Reasonable agreement is found between EAR spectra and our theory. Protein acoustic modes have been extensively studied theoretically to assess the role they play in protein function; this result suggests EAR spectroscopy as a new experimental tool for studies of protein acoustic modes.

  20. Acoustic concerns related to multi cultural societies

    DEFF Research Database (Denmark)

    Gade, Anders Christian

    2001-01-01

    Immigration has increased cultural diversity in western societies. The process of integrating immigrants into their host countries can be smoothed if acousticians learn to recognize (1) the acoustic traditions of immigrant cultures and (2) the specific acoustic needs of the new society members. Two...... related projects are discussed. The ``Cahrisma'' project (Conservation of Acoustical Heritage by the Revival and Identification of the Sinan's Mosque Acoustics) is sponsored by the European Commission and carried out in cooperation among researchers in Turkey, Malta, Italy, France, Switzerland...

  1. Propagation behavior of acoustic wave in wood

    Institute of Scientific and Technical Information of China (English)

    Huadong Xu; Guoqi Xu; Lihai Wang; Lei Yu

    2014-01-01

    We used acoustic tests on a quarter-sawn poplar timbers to study the effects of wood anisotropy and cavity defects on acoustic wave velocity and travel path, and we investigated acoustic wave propagation behavior in wood. The timber specimens were first tested in unmodified condition and then tested after introduction of cavity defects of varying sizes to quantify the transmitting time of acoustic waves in laboratory conditions. Two-dimensional acoustic wave contour maps on the radial section of specimens were then simulated and analyzed based on the experimental data. We tested the relationship between wood grain and acoustic wave velocity as waves passed in various directions through wood. Wood anisotropy has significant effects on both velocity and travel path of acoustic waves, and the velocity of waves passing longitudinally through timbers exceeded the radial velocity. Moreover, cavity defects altered acoustic wave time contours on radial sections of timbers. Acous-tic wave transits from an excitation point to the region behind a cavity in defective wood more slowly than in intact wood.

  2. Acoustics of finite-aperture vortex beams

    CERN Document Server

    Mitri, F G

    2014-01-01

    A method based on the Rayleigh-Sommerfeld surface integral is provided, which makes it feasible to rigorously model, evaluate and compute the acoustic scattering and other mechanical effects of finite-aperture vortex beams such as the acoustic radiation force and torque on a viscoelastic sphere in various applications in acoustic tweezers and microfluidics, particle entrapment, manipulation and rotation. Partial-wave series expansions are derived for the incident field of acoustic spiraling (vortex) beams, comprising high-order Bessel and Bessel-Gauss beams.

  3. Acoustic resonance for nonmetallic mine detection

    Energy Technology Data Exchange (ETDEWEB)

    Kercel, S.W.

    1998-04-01

    The feasibility of acoustic resonance for detection of plastic mines was investigated by researchers at the Oak Ridge National Laboratory`s Instrumentation and Controls Division under an internally funded program. The data reported in this paper suggest that acoustic resonance is not a practical method for mine detection. Representative small plastic anti-personnel mines were tested, and were found to not exhibit detectable acoustic resonances. Also, non-metal objects known to have strong acoustic resonances were tested with a variety of excitation techniques, and no practical non-contact method of exciting a consistently detectable resonance in a buried object was discovered. Some of the experimental data developed in this work may be useful to other researchers seeking a method to detect buried plastic mines. A number of excitation methods and their pitfalls are discussed. Excitation methods that were investigated include swept acoustic, chopped acoustic, wavelet acoustic, and mechanical shaking. Under very contrived conditions, a weak response that could be attributed to acoustic resonance was observed, but it does not appear to be practical as a mine detection feature. Transfer properties of soil were investigated. Impulse responses of several representative plastic mines were investigated. Acoustic leakage coupling, and its implications as a disruptive mechanism were investigated.

  4. Sonic effervescence: A tutorial on acoustic cavitation

    Energy Technology Data Exchange (ETDEWEB)

    Apfel, R.E. [Yale University, New Haven, Connecticut 06520-8286 (United States)

    1997-03-01

    This article on acoustic cavitation is a revision of a tutorial lecture presented at the Acoustical Society of America meeting in Austin, Texas, on 28 November 1994. The general approach adopted here differs from a review article in stressing the overarching themes that come under the category of acoustic cavitation, rather than being an encyclopedic reference on the topic. When possible, specific order-of-magnitude estimates have been given so that the reader can better understand the particular phenomena being described. The basic physics is discussed, and applications are reviewed with the goal of putting them in a useful context. {copyright} {ital 1997 Acoustical Society of America.}

  5. A short history of bad acoustics.

    Science.gov (United States)

    Wright, M C M

    2006-10-01

    Every branch of science attracts its share of cranks and pseudoscientists, and acoustics has been no exception. A brief survey of those who touched on acoustics is given with quotations from the more interesting or egregious examples. A contrast is drawn between the nineteenth century contrarian's quarrel with particular theories and the modern new age wholesale rejection of theory. This world-view is traced back to the later scientific writings of Goethe. Examples of pseudoscience applied to biomedical acoustics, architectural acoustics, and audio reproduction are given.

  6. Wise teachers train better DNN acoustic models

    National Research Council Canada - National Science Library

    Ryan Price; Ken-ichi Iso; Koichi Shinoda

    2016-01-01

    .... Neural network acoustic models that can utilize speaker-adaptive features, have deep and wide layers, or more computationally expensive architectures, for example, often obtain best recognition...

  7. Acoustic concentration of particles in fluid flow

    Science.gov (United States)

    Ward, Michael D.; Kaduchak, Gregory

    2010-11-23

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

  8. Acoustic concentration of particles in fluid flow

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Michael W.; Kaduchak, Gregory

    2017-08-15

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

  9. Vowel Acoustic Space Development in Children: A Synthesis of Acoustic and Anatomic Data

    Science.gov (United States)

    Vorperian, Houri K.; Kent, Ray D.

    2007-01-01

    Purpose: This article integrates published acoustic data on the development of vowel production. Age specific data on formant frequencies are considered in the light of information on the development of the vocal tract (VT) to create an anatomic-acoustic description of the maturation of the vowel acoustic space for English. Method: Literature…

  10. Thermo-acoustic Sound Generation in the Interaction of Pulsed Proton and Laser Beams with a Water Target

    CERN Document Server

    Lahmann, R; Graf, K; Hößl, J; Kappes, A; Katz, U; Mecke, K; Schwemmer, S

    2015-01-01

    The generation of hydrodynamic radiation in interactions of pulsed proton and laser beams with matter is explored. The beams were directed into a water target and the resulting acoustic signals were recorded with pressure sensitive sensors. Measurements were performed with varying pulse energies, sensor positions, beam diameters and temperatures. The obtained data are matched by simulation results based on the thermo-acoustic model with uncertainties at a level of 10%. The results imply that the primary mechanism for sound generation by the energy deposition of particles propagating in water is the local heating of the medium. The heating results in a fast expansion or contraction and a pressure pulse of bipolar shape is emitted into the surrounding medium. An interesting, widely discussed application of this effect could be the detection of ultra-high energetic cosmic neutrinos in future large-scale acoustic neutrino detectors. For this application a validation of the sound generation mechanism to high accur...

  11. Identification of Acoustic-Vibratory System by Acoustic Measurement

    Directory of Open Access Journals (Sweden)

    Takuzo Iwatsubo

    1996-01-01

    Full Text Available A new method for reducing ill-conditioning in a class of identification problems is proposed. The key point of the method is that the identified vibration of the sound source is expressed as a superposition of vibration modes. The mathematical property of the coefficient matrix, the practical error expanding ratio, and the stochastic error expanding ratio are investigated in a numerical example. The mode-superposition method is shown to be an effective tool for acoustic-vibratory inverse analysis.

  12. An aeroacoustically driven thermoacoustic heat pump.

    Science.gov (United States)

    Slaton, W V; Zeegers, J C H

    2005-06-01

    The mean flow of gas in a pipe past a cavity can excite the resonant acoustic modes of the cavity--much like blowing across the top of a bottle. The periodic shedding of vortices from the leading edge of the mouth of the cavity feeds energy into the acoustic modes which, in turn, affect the shedding of the next vortex. This so-called aeroacoustic whistle can excite very high amplitude acoustic standing waves within a cavity defined by coaxial side branches closed at their ends. The amplitude of these standing waves can easily be 20% of the ambient pressure at optimal gas flow rates and ambient pressures within the main pipe. A standing wave thermoacoustic heat pump is a device which utilizes the in-phase pressure and displacement oscillations to pump heat across a porous medium thereby establishing, or maintaining, a temperature gradient. Experimental results of a combined system of aeroacoustic sound source and a simple thermoacoustic stack will be presented.

  13. Starch viscoelastic properties studied with an acoustic wave sensor.

    Science.gov (United States)

    Santos, M D; Gomes, M T S R

    2014-01-01

    Gelatinization and retrogradation of starch was followed in real time with an acoustic wave sensor. This study relies on the monitorization of the frequency of oscillation of a piezoelectric quartz crystal in contact with a 2.5% emulsion of a commercial maize starch, during heating and cooling. The technique showed to be very powerful and sensitive to most of the changes described in the literature, which have been elucidated by some other techniques. The value for the temperature of gelatinization found using the sensor was confirmed by the analysis of the same starch emulsion by polarized light microscopy. Temperatures of gelatinization were found to vary with the sample heating rate, as follows: 73.5 °C at 2.0 °C/min, 66.0 °C at 1.0 °C/min, and 65.0 °C at 0.5 °C/min. Hysteresis of the studied system was evidenced by the frequency shift before heating and after cooling till the initial temperature. Analysis performed on a 1.5% emulsion of a rice starch heated at 2.0 °C/min and cooled as before, evidenced no hysteresis and showed complete reversibility, in which concerns to the series frequency of the piezoelectric quartz crystal. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Liquid rocket combustion chamber acoustic characterization

    Directory of Open Access Journals (Sweden)

    Cândido Magno de Souza

    2010-09-01

    Full Text Available Over the last 40 years, many solid and liquid rocket motors have experienced combustion instabilities. Among other causes, there is the interaction of acoustic modes with the combustion and/or fluid dynamic processes inside the combustion chamber. Studies have been showing that, even if less than 1% of the available energy is diverted to an acoustic mode, combustion instability can be generated. On one hand, this instability can lead to ballistic pressure changes, couple with other propulsion systems such as guidance or thrust vector control, and in the worst case, cause motor structural failure. In this case, measures, applying acoustic techniques, must be taken to correct/minimize these influences on the combustion. The combustion chamber acoustic behavior in operating conditions can be estimated by considering its behavior in room conditions. In this way, acoustic tests can be easily performed, thus identifying the cavity modes. This paper describes the procedures to characterize the acoustic behavior in the inner cavity of four different configurations of a combustion chamber. Simple analytical models are used to calculate the acoustic resonance frequencies and these results are compared with acoustic natural frequencies measured at room conditions. Some comments about the measurement procedures are done, as well as the next steps for the continuity of this research. The analytical and experimental procedures results showed good agreement. However, limitations on high frequency band as well as in the identification of specific kinds of modes indicate that numerical methods able to model the real cavity geometry and an acoustic experimental modal analysis may be necessary for a more complete analysis. Future works shall also consider the presence of passive acoustic devices such as baffles and resonators capable of introducing damping and avoiding or limiting acoustic instabilities.

  15. Airy acoustical-sheet spinner tweezers

    Science.gov (United States)

    Mitri, F. G.

    2016-09-01

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

  16. Heat Related Illnesses

    Institute of Scientific and Technical Information of China (English)

    Robert Carter III; Samuel N. Cheuvront; Michael N. Sawka

    2007-01-01

    @@ KEY POINTS · Heat illnesses range in severity from mild (heat rash, heat syncope, cramps) to serious (heat exhaustion, heat injury, heat stroke). · Although heat illness can occur in anyone, an increased risk is associated with a variety of environmental factors, personal characteristics,health conditions, and medications.

  17. Geothermal district heating systems

    Science.gov (United States)

    Budney, G. S.; Childs, F.

    1982-06-01

    Ten district heating demonstration projects and their present status are described. The projects are Klamath County YMCA, Susanville District Heating, Klamath Falls District Heating, Reno Salem Plaza Condominium, El Centro Community Center Heating/Cooling, Haakon School and Business District Heating, St. Mary's Hospital, Diamond Ring Ranch, Pagosa Springs District Heating, and Boise District Heating.

  18. Identification of Turbomachinery Noise Sources Using Acoustical Holography Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Evaluation and enhancement of the acoustical performance of turbomachinery requires knowledge of the acoustic sources. However, the noise generation mechanisms...

  19. A heat-driven thermoacoustic cryocooler capable of reaching below liquid hydrogen temperature

    Institute of Scientific and Technical Information of China (English)

    HU JianYing; LUO ErCang; DAI Wei; Zhou Yuan

    2007-01-01

    A "double-gas acoustic amplifier" is introduced to couple a thermoacoustic heat engine and a two-stage pulse tube cooler in this paper. Compared with previous acoustic amplifiers, this new acoustic amplifier maintains the function of amplification for pressure amplitude. In particular, the novel acoustic amplifier with a reservoir makes it possible to install an acoustic transparent but gas blocking elastic membrane between the engine and the cooler. Thus, the engine can use nitrogen as the working gas to work at low frequency; and meanwhile, the cooler can still use helium as the working gas to maintain its high performance. With this new amplifier, the cooling temperature of a two-stage pulse tube cooler driven by an energy-focused thermoacoustic engine reached 18.7 K.

  20. An overview of acoustic telemetry

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Acoustic emission methodology and application

    CERN Document Server

    Nazarchuk, Zinoviy; Serhiyenko, Oleh

    2017-01-01

    This monograph analyses in detail the physical aspects of the elastic waves radiation during deformation or fracture of materials. I presents the  methodological bases for the practical use of acoustic emission device, and describes the results of theoretical and experimental researches of evaluation of the crack growth resistance of materials, selection of the useful AE signals. The efficiency of this methodology is shown through the diagnostics of various-purpose industrial objects. The authors obtain results of experimental researches with the help of the new methods and facilities.

  2. Surface Acoustic Wave Frequency Comb

    CERN Document Server

    Savchenkov, A A; Ilchenko, V S; Seidel, D; Maleki, L

    2011-01-01

    We report on realization of an efficient triply-resonant coupling between two long lived optical modes and a high frequency surface acoustic wave (SAW) mode of the same monolithic crystalline whispering gallery mode resonator. The coupling results in an opto-mechanical oscillation and generation of a monochromatic SAW. A strong nonlinear interaction of this mechanical mode with other equidistant SAW modes leads to mechanical hyper-parametric oscillation and generation of a SAW pulse train and associated frequency comb in the resonator. We visualized the comb observing the modulation of the modulated light escaping the resonator.

  3. Physical acoustics principles and methods

    CERN Document Server

    Mason, Warren P

    1964-01-01

    Physical Acoustics: Principles and Methods, Volume l-Part A focuses on high frequency sound waves in gases, liquids, and solids that have been proven as powerful tools in analyzing the molecular, defect, domain wall, and other types of motions. The selection first tackles wave propagation in fluids and normal solids and guided wave propagation in elongated cylinders and plates. Discussions focus on fundamentals of continuum mechanics; small-amplitude waves in a linear viscoelastic medium; representation of oscillations and waves; and special effects associated with guided elastic waves in plat

  4. Sonochemistry and the acoustic bubble

    CERN Document Server

    Grieser, Franz; Enomoto, Naoya; Harada, Hisashi; Okitsu, Kenji; Yasui, Kyuichi

    2015-01-01

    Sonochemistry and the Acoustic Bubble provides an introduction to the way ultrasound acts on bubbles in a liquid to cause bubbles to collapse violently, leading to localized 'hot spots' in the liquid with temperatures of 5000° celcius and under pressures of several hundred atmospheres. These extreme conditions produce events such as the emission of light, sonoluminescence, with a lifetime of less than a nanosecond, and free radicals that can initiate a host of varied chemical reactions (sonochemistry) in the liquid, all at room temperature. The physics and chemistry behind the p

  5. Superhigh Temperatures and Acoustic Cavitation

    CERN Document Server

    Belyaev, V B; Miller, M B; Sermyagin, A V; Topolnikov, A S

    2003-01-01

    The experimental results on thermonuclear synthesis under acoustic cavitation have been analyzed with the account of the latest data and their discussion. The analysis testifies that this avenue of research is a very promising one. The numerical calculations of the D(d, n)^{3}He reaction rate in the deuterated acetone (C_{3}D_{6}O) under the influence of ultrasound depending on T environment temperature within the range T=249-295 K have been carried out within the framework of hydrodynamic model. The results show that it is possible to improve substantially the effect/background relationship in experiments by decreasing the fluid temperature twenty-thirty degrees below zero.

  6. OFDM for underwater acoustic communications

    CERN Document Server

    Zhou, Shengli

    2014-01-01

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

  7. Introducing passive acoustic filter in acoustic based condition monitoring: Motor bike piston-bore fault identification

    Science.gov (United States)

    Jena, D. P.; Panigrahi, S. N.

    2016-03-01

    Requirement of designing a sophisticated digital band-pass filter in acoustic based condition monitoring has been eliminated by introducing a passive acoustic filter in the present work. So far, no one has attempted to explore the possibility of implementing passive acoustic filters in acoustic based condition monitoring as a pre-conditioner. In order to enhance the acoustic based condition monitoring, a passive acoustic band-pass filter has been designed and deployed. Towards achieving an efficient band-pass acoustic filter, a generalized design methodology has been proposed to design and optimize the desired acoustic filter using multiple filter components in series. An appropriate objective function has been identified for genetic algorithm (GA) based optimization technique with multiple design constraints. In addition, the sturdiness of the proposed method has been demonstrated in designing a band-pass filter by using an n-branch Quincke tube, a high pass filter and multiple Helmholtz resonators. The performance of the designed acoustic band-pass filter has been shown by investigating the piston-bore defect of a motor-bike using engine noise signature. On the introducing a passive acoustic filter in acoustic based condition monitoring reveals the enhancement in machine learning based fault identification practice significantly. This is also a first attempt of its own kind.

  8. New Developments in Auxiliary Heating

    Science.gov (United States)

    Norreys, Peter

    2016-10-01

    The role of heating arising from the propagation of orthogonal petawatt-laser driven relativistic electron beams in dense plasma will be discussed. The energy cascade mechanism begins first with the rapid growth at 45 degrees to the two beams of electrostatic waves near the electron plasma frequency. These waves reach high amplitudes and break, which then results in the generation of a strongly driven turbulent Langmuir spectrum. Parametric decay of these waves, particularly via the modulational instability, then gives rise to a coupled turbulent ion acoustic spectrum. The resulting waves also give rise to ion heating through collisions via equilibration of both electrons and ions. In this talk, I will present the most recent analytic modelling, and particle-in-cell / Vlasov-Poisson simulation results from my team within Oxford Physics and the Central Laser Facility that explores the optimum parameter space for this process, focusing in particular on the requirements for auxiliary heating of the central hot spot in inertial confinement fusion target experiments. I will also describe new methods for hole-boring through the coronal plasma surrounding the fuel using strongly relativistic laser beams that demonstrates the strong suppression of the hosing instability under these conditions. Proof-of-concept experiments are under design for the Orion and OMEGA EP facilities.

  9. Enhanced Acoustic Emission in Relation to the Acoustic Halo Surrounding Active Region 11429

    CERN Document Server

    Hanson, Chris S; Leka, K D

    2015-01-01

    The use of acoustic holography in the high-frequency $p$-mode spectrum can resolve the source distributions of enhanced acoustic emissions within halo structures surrounding active regions. In doing so, statistical methods can then be applied to ascertain relationships with the magnetic field. This is the focus of this study. The mechanism responsible for the detected enhancement of acoustic sources around solar active regions has not yet been explained. Furthermore the relationship between the magnetic field and enhanced acoustic emission has not yet been comprehensively examined. We have used vector magnetograms from the \\Helioseismic and Magnetic Imager (HMI) on-board the Solar Dynamics Observatory (SDO) to image the magnetic-field properties in the halo. We have studied the acoustic morphology of an active region, with a complex halo and "glories," and we have linked some acoustic properties to the magnetic-field configuration. In particular, we find that acoustic sources are significantly enhanced in reg...

  10. Acoustical and optical radiation pressure and the development of single beam acoustical tweezers

    Science.gov (United States)

    Thomas, Jean-Louis; Marchiano, Régis; Baresch, Diego

    2017-07-01

    Studies on radiation pressure in acoustics and optics have enriched one another and have a long common history. Acoustic radiation pressure is used for metrology, levitation, particle trapping and actuation. However, the dexterity and selectivity of single-beam optical tweezers are still to be matched with acoustical devices. Optical tweezers can trap, move and position micron size particles, biological samples or even atoms with subnanometer accuracy in three dimensions. One limitation of optical tweezers is the weak force that can be applied without thermal damage due to optical absorption. Acoustical tweezers overcome this limitation since the radiation pressure scales as the field intensity divided by the speed of propagation of the wave. However, the feasibility of single beam acoustical tweezers was demonstrated only recently. In this paper, we propose a historical review of the strong similarities but also the specificities of acoustical and optical radiation pressures, from the expression of the force to the development of single-beam acoustical tweezers.

  11. Active acoustic leak detection for LMFBR steam generator. Sound attenuation due to bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Kumagai, Hiromichi; Sakuma, Toshio [Central Research Inst. of Electric Power Industry, Komae, Tokyo (Japan). Komae Research Lab.

    1995-06-01

    In the steam generators (SG) of LMFBR, it is necessary to detect the leakage of water from tubes of heat exchangers as soon as it occurs. The active acoustic detection method has drawn general interest owing to its short response time and reduction of the influence of background noise. In this paper, the application of the active acoustic detection method for SG is proposed, and sound attenuation by bubbles is investigated experimentally. Furthermore, using the SG sector model, sound field characteristics and sound attenuation characteristics due to injection of bubbles are studied. It is clarified that the sound attenuation depends upon bubble size as well as void fraction, that the distance attenuation of sound in the SG model containing heat transfer tubes is 6dB for each two-fold increase of distance, and that emitted sound attenuates immediately upon injection of bubbles. (author).

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

    Science.gov (United States)

    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.

  13. Applications of Acoustics and Cavitation to Noninvasive Therapy and Drug Delivery

    Science.gov (United States)

    Coussios, Constantin C.; Roy, Ronald A.

    2008-01-01

    Biomedical acoustics is rapidly evolving from a diagnostic modality into a therapeutic tool, and acoustic cavitation is often the common denominator in a wide range of new therapeutic applications. High-intensity focused ultrasound (HIFU) waves generated outside the body can be used to deposit heat deep within the body. Through a quantitative analysis of heat deposition by ultrasound, it is shown that inertial cavitation can help address some of the major challenges of HIFU therapy by providing a means of enhancing and monitoring treatment noninvasively. In the context of drug delivery, both inertial and stable cavitation play roles in enhancing drug activity and uptake. In particular, shape oscillations arising during stable cavitation provide an effective micropumping mechanism for enhanced mass transport across inaccessible interfaces.

  14. Acoustic Emission Analysis of Damage Progression in Thermal Barrier Coatings Under Thermal Cyclic Conditions

    Science.gov (United States)

    Appleby, Matthew; Zhu, Dongming; Morscher, Gregory

    2015-01-01

    Damage evolution of electron beam-physical vapor deposited (EBVD-PVD) ZrO2-7 wt.% Y2O3 thermal barrier coatings (TBCs) under thermal cyclic conditions was monitored using an acoustic emission (AE) technique. The coatings were heated using a laser heat flux technique that yields a high reproducibility in thermal loading. Along with AE, real-time thermal conductivity measurements were also taken using infrared thermography. Tests were performed on samples with induced stress concentrations, as well as calcium-magnesium-alumino-silicate (CMAS) exposure, for comparison of damage mechanisms and AE response to the baseline (as-produced) coating. Analysis of acoustic waveforms was used to investigate damage development by comparing when events occurred, AE event frequency, energy content and location. The test results have shown that AE accumulation correlates well with thermal conductivity changes and that AE waveform analysis could be a valuable tool for monitoring coating degradation and provide insight on specific damage mechanisms.

  15. Validation of a numerical model of acoustic ceiling combined with TABS

    DEFF Research Database (Denmark)

    Rage, Nils; Kazanci, Ongun Berk; Olesen, Bjarne W.

    2016-01-01

    to understand to which extent a layer of hanging sound absorbers will impede the heating and cooling performance of the system, and how this translates on the thermal comfort for the occupants. In order to address these issues, this study focuses on validation of a new TRNSYS component (Type Ecophon Acoustic...... Elements) developed to simulate partially covered suspended ceilings such as hanging sound absorbers. The tool is validated by numerically modelling a set of similar experiments carried out in full-scale by a previous study. For this, a total of 12 scenarios from two case studies have been modelled......Thermally-Active Building Systems (TABS) have proven to be an energy-efficient and economical cooling and heating solution for commercial buildings. However, acoustic comfort is often jeopardized in such buildings, due to the thermal requirements of the system. More knowledge is required...

  16. Acoustic characteristics of Danish infant directed speech

    DEFF Research Database (Denmark)

    Bohn, Ocke-Schwen

    2013-01-01

    Danish presents several challenges for language learners, such as a very densely packed upper portion of the acoustic vowel space, and a sibilant contrast that is acoustically less distinct than in e.g. English. The present study examined whether Danish caregivers enhance Danish contrasts when......'s receptive vocabulary knowledge....

  17. Acoustic quality and sound insulation between dwellings

    DEFF Research Database (Denmark)

    Rindel, Jens Holger

    1998-01-01

    to another, however, several of the results show a slope around 4 % per dB. The results may be used to evaluate the acoustic quality level of a certain set of sound insulation requirements, or they may be used as a basis for specifying the desired acoustic quality of future buildings...

  18. Acoustic Pattern Recognition on Android Devices

    DEFF Research Database (Denmark)

    Møller, Maiken Bjerg; Gaarsdal, Jesper; Steen, Kim Arild

    2013-01-01

    an Android application developed for acoustic pattern recognition of bird species. The acoustic data is recorded using a built-in microphone, and pattern recognition is performed on the device, requiring no network connection. The algorithm is implemented in C++ as a native Android module and the Open...

  19. Environmental Fluctuations and Acoustic Data Communications

    Science.gov (United States)

    2015-09-30

    GOALS Couple together analytical and numerical modeling of oceanographic and surface wave processes, acoustic propagation modeling, statistical...acoustic digital data communication systems in shallow water. OBJECTIVES Develop analytical /numerical models, validated with experimental data...simplified geometry simulated. An asymmetric source- receiver geometry results in a striation pattern that is dominated by upward or downward

  20. Nonadhesive acoustic membranes based on polyimide

    Directory of Open Access Journals (Sweden)

    Vorob'ev A.V.

    2014-02-01

    Full Text Available The paper presents a comparison of technical characteristics of acoustic membranes with an adhesive layer and nonadhesive membranes. The authors present the manufacturing technology for acoustic membranes based on aluminum-polyimide film dielectrics and analyze the advantages of such membranes in comparison to other sound emitters.

  1. Acoustic quality and sound insulation between dwellings

    DEFF Research Database (Denmark)

    Rindel, Jens Holger

    1999-01-01

    to another, however, several of the results show a slope around 4 % per dB. The results may be used to evaluate the acoustic quality level of a certain set of sound insulation requirements, or they may be used as a basis for specifying the desired acoustic quality of future buildings....

  2. Room acoustic properties of concert halls

    DEFF Research Database (Denmark)

    Gade, Anders Christian

    1996-01-01

    A large database of values of various room acoustic parameters has provided the basis for statistical analyses of how and how much the acoustic properties of concert halls are influenced by their size, shape, and absorption area (as deduced from measured reverberation time). The data have been...

  3. Acoustics in rock and pop music halls

    DEFF Research Database (Denmark)

    Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian

    2007-01-01

    The existing body of literature regarding the acoustic design of concert halls has focused almost exclusively on classical music, although there are many more performances of rhythmic music, including rock and pop. Objective measurements were made of the acoustics of twenty rock music venues...

  4. NPS Ocean Acoustics Laboratory Marine Mammal Research

    OpenAIRE

    Chiu, Ching-Sang; Collins, Curtis; Joseph, John; Margolina, Tetyana; Stimpert, Alison; Miller, Chris

    2014-01-01

    The Marine Mammal Group within the Ocean Acoustics Laboratory at NPS is involved with a range of research studying marine mammal acoustics , both sound production and effects of anthropogenic sound on marine mammals. A sampling of our research is described below.

  5. The South Pole Acoustic Test Setup (SPATS)

    Science.gov (United States)

    Laihem, Karim; IceCube Collaboration

    2012-11-01

    New detection techniques for (GZK) neutrinos are required for instrumenting a large detector volume needed to observe the low neutrino fluxes at the EeV energy range. Studies on a larger IceCube Neutrino Observatory at the South Pole have been intensively investigated in the last decade. A larger effective volume at a reasonable cost is possible if an acoustic array is a part of a large hybrid detector which includes radio and the existing optical array. The feasibility and the physics capabilities of an acoustic array at the South Pole depend on the knowledge of the acoustic properties of the ice such as the sound speed, the attenuation length, the background noise level and the transient rate. To investigate the ice properties, the first three acoustic strings of the South Pole Acoustic Test Setup (SPATS) have been deployed in the austral summer 2006/2007, then completed with an additional string in 2007/2008. With its four strings SPATS was able to evaluate in situ the acoustic properties of the South Pole ice in the 10-100 kHz frequency range. In this paper the performance of SPATS is described, results on the acoustic ice properties are presented and a new drilling method to deploy acoustic strings in ice is introduced.

  6. The South Pole Acoustic Test Setup (SPATS)

    Energy Technology Data Exchange (ETDEWEB)

    Laihem, Karim, E-mail: karim.laihem@physik.rwth-aachen.de [III Physikalisches Institut B, Physikzentrum, RWTH Aachen University, Otto-Blumenthal Strasse, 52074 Aachen (Germany)

    2012-11-11

    New detection techniques for (GZK) neutrinos are required for instrumenting a large detector volume needed to observe the low neutrino fluxes at the EeV energy range. Studies on a larger IceCube Neutrino Observatory at the South Pole have been intensively investigated in the last decade. A larger effective volume at a reasonable cost is possible if an acoustic array is a part of a large hybrid detector which includes radio and the existing optical array. The feasibility and the physics capabilities of an acoustic array at the South Pole depend on the knowledge of the acoustic properties of the ice such as the sound speed, the attenuation length, the background noise level and the transient rate. To investigate the ice properties, the first three acoustic strings of the South Pole Acoustic Test Setup (SPATS) have been deployed in the austral summer 2006/2007, then completed with an additional string in 2007/2008. With its four strings SPATS was able to evaluate in situ the acoustic properties of the South Pole ice in the 10-100 kHz frequency range. In this paper the performance of SPATS is described, results on the acoustic ice properties are presented and a new drilling method to deploy acoustic strings in ice is introduced.

  7. Eliminating transducer distortion in acoustic measurements

    DEFF Research Database (Denmark)

    Agerkvist, Finn T.; Torras Rosell, Antoni; McWalter, Richard Ian

    2014-01-01

    This paper investigates the in uence of nonlinear components that contaminate the linear response of acoustic transducer, and presents a method for eliminating the in uence of nonlinearities in acoustic measurements. The method is evaluated on simulated as well as experimental data, and is shown...

  8. Design basis of industrial acoustic separators

    NARCIS (Netherlands)

    Cappon, H.J.; Keesman, K.J.

    2013-01-01

    This study presents the process of obtaining a basic design for an industrial scale acoustic separator based on flow characteristics inside the separation chamber, on acoustic analysis within the chamber and calculated particle trajectories combining these two analyses. Adequate criteria for subsequ

  9. An Optimisation Approach for Room Acoustics Design

    DEFF Research Database (Denmark)

    Holm-Jørgensen, Kristian; Kirkegaard, Poul Henning; Andersen, Lars

    2005-01-01

    This paper discuss on a conceptual level the value of optimisation techniques in architectural acoustics room design from a practical point of view. It is chosen to optimise one objective room acoustics design criterium estimated from the sound field inside the room. The sound field is modeled...

  10. Spectral statistics of the acoustic stadium

    Science.gov (United States)

    Méndez-Sánchez, R. A.; Báez, G.; Leyvraz, F.; Seligman, T. H.

    2014-01-01

    We calculate the normal-mode frequencies and wave amplitudes of the two-dimensional acoustical stadium. We also obtain the statistical properties of the acoustical spectrum and show that they agree with the results given by random matrix theory. Some normal-mode wave amplitudes showing scarring are presented.

  11. Subwoofer and nanotube butterfly acoustic flame extinction

    Science.gov (United States)

    Aliev, Ali E.; Mayo, Nathanael K.; Baughman, Ray H.; Mills, Brent T.; Habtour, Ed

    2017-07-01

    Nonchemical flame control using acoustic waves from a subwoofer and a lightweight carbon nanotube thermoacoustic projector was demonstrated. The intent was to manipulate flame intensity, direction and propagation. The mechanisms of flame suppression using low frequency acoustic waves were discussed. Laminar flame control and extinction were achieved using a thermoacoustic ‘butterfly’ projector based on freestanding carbon nanotube sheets.

  12. Acoustic Pattern Recognition on Android Devices

    DEFF Research Database (Denmark)

    Møller, Maiken Bjerg; Gaarsdal, Jesper; Steen, Kim Arild

    2013-01-01

    an Android application developed for acoustic pattern recognition of bird species. The acoustic data is recorded using a built-in microphone, and pattern recognition is performed on the device, requiring no network connection. The algorithm is implemented in C++ as a native Android module and the Open...

  13. On Collisionless Damping of Ion Acoustic Waves

    DEFF Research Database (Denmark)

    Jensen, Vagn Orla; Petersen, P.I.

    1973-01-01

    Exact theoretical treatments show that the damping of ion acoustic waves in collisionless plasmas does not vanish when the derivative of the undisturbed distribution function at the phase velocity equals zero.......Exact theoretical treatments show that the damping of ion acoustic waves in collisionless plasmas does not vanish when the derivative of the undisturbed distribution function at the phase velocity equals zero....

  14. NONINVASIVE MEASUREMENT OF LOCAL THERMAL DIFFUSIVITY USING BACKSCATTERED ULTRASOUND AND FOCUSED ULTRASOUND HEATING

    OpenAIRE

    2008-01-01

    Previously, noninvasive methods of estimating local tissue thermal and acoustic properties using backscattered ultrasound have been proposed in the literature. In this article, a noninvasive method of estimating local thermal diffusivity in situ during focused ultrasound heating using beamformed acoustic backscatter data and applying novel signal processing techniques is developed. A high intensity focused ultrasound (HIFU) transducer operating at subablative intensities is employed to create...

  15. Three-dimensional nonlinear acoustical holography

    Science.gov (United States)

    Niu, Yaying

    Nearfield Acoustical Holography (NAH) is an acoustic field visualization technique that can be used to reconstruct three-dimensional (3-D) acoustic fields by projecting two-dimensional (2-D) data measured on a hologram surface. However, linear NAH algorithms developed and improved by many researchers can result in significant reconstruction errors when they are applied to reconstruct 3-D acoustic fields that are radiated from a high-level noise source and include significant nonlinear components. Here, planar, nonlinear acoustical holography procedures are developed that can be used to reconstruct 3-D, nonlinear acoustic fields radiated from a high-level noise source based on 2-D acoustic pressure data measured on a hologram surface. The first nonlinear acoustic holography procedure is derived for reconstructing steady-state acoustic pressure fields by applying perturbation and renormalization methods to nonlinear, dissipative, pressure-based Westervelt Wave Equation (WWE). The nonlinear acoustic pressure fields radiated from a high-level pulsating sphere and an infinite-size, vibrating panel are used to validate this procedure. Although the WWE-based algorithm is successfully validated by those two numerical simulations, it still has several limitations: (1) Only the fundamental frequency and its second harmonic nonlinear components can be reconstructed; (2) the application of this algorithm is limited to mono-frequency source cases; (3) the effects of bent wave rays caused by transverse particle velocities are not included; (4) only acoustic pressure fields can be reconstructed. In order to address the limitations of the steady-state, WWE-based procedure, a transient, planar, nonlinear acoustic holography algorithm is developed that can be used to reconstruct 3-D nonlinear acoustic pressure and particle velocity fields. This procedure is based on Kuznetsov Wave Equation (KWE) that is directly solved by using temporal and spatial Fourier Transforms. When compared

  16. International Conference on Acoustics and Vibration

    CERN Document Server

    Chaari, Fakher; Walha, Lasaad; Abdennadher, Moez; Abbes, Mohamed; Haddar, Mohamed

    2017-01-01

    The book provides readers with a snapshot of recent research and industrial trends in field of industrial acoustics and vibration. Each chapter, accepted after a rigorous peer-review process, reports on a selected, original piece of work presented and discussed at International Conference on Acoustics and Vibration (ICAV2016), which was organized by the Tunisian Association of Industrial Acoustics and Vibration (ATAVI) and held March 21-23, in Hammamet, Tunisia. The contributions, mainly written by north African authors, covers advances in both theory and practice in a variety of subfields, such as: smart materials and structures; fluid-structure interaction; structural acoustics as well as computational vibro-acoustics and numerical methods. Further topics include: engines control, noise identification, robust design, flow-induced vibration and many others.This book provides a valuable resource for both academics and professionals dealing with diverse issues in applied mechanics. By combining advanced theori...

  17. Worship space acoustics 3 decades of design

    CERN Document Server

    Ryherd, Erica; Ronsse, Lauren

    2016-01-01

    This book takes the reader on a wide-ranging tour through churches, synagogues, mosques, and other worship spaces designed during the past 30 years. The book begins with a series of essays on topics ranging from the soundscape of worship spaces to ecclesiastical design at the turn of the 21st Century. Perspective pieces from an architect, audio designer, music director, and worship space owner are also included. The core of the book presents the acoustical and architectural design of a wide variety of individual worship space venues. Acoustical consulting firms, architects, and worship space designers from across the world contributed their recent innovative works in the area of worship space acoustics. The contributions include detailed renderings and architectural drawings, as well as informative acoustic data graphs and evocative descriptions of the spaces. Filled with beautiful photography and fascinating modern design, this book is a must-read for anyone interested in religious architecture, acoustical d...

  18. Auditorium Acoustics From Past to Present

    Directory of Open Access Journals (Sweden)

    Kabiru Maishanu

    2017-01-01

    Full Text Available The main aim of this paper is to identify how acoustics where generally achieve in auditoriums base on the method, technics and the materials been used. This paper will discuss the transition over time. It will cover how the design began from the past (Roman, Greek baroque, renaissance periods to the present (twentieth century. The paper will further discuss some case studies which are from different periods. The selection of the case study was based on their excellent acoustics qualities of the spaces. It will provide better understanding on how acoustics solution where been achieve in auditoriums/theaters from the past to the present. Finally, the paper will point out some major benefits of using acoustics in auditoriums and also discuss on what causes poor quality sound in the present auditoriums and then suggest the use flat panels technology and line-stone material as it has great impact in in achieving good and qualitative acoustics in the past.

  19. Pulsed-Source Interferometry in Acoustic Imaging

    Science.gov (United States)

    Shcheglov, Kirill; Gutierrez, Roman; Tang, Tony K.

    2003-01-01

    A combination of pulsed-source interferometry and acoustic diffraction has been proposed for use in imaging subsurface microscopic defects and other features in such diverse objects as integrated-circuit chips, specimens of materials, and mechanical parts. A specimen to be inspected by this technique would be mounted with its bottom side in contact with an acoustic transducer driven by a continuous-wave acoustic signal at a suitable frequency, which could be as low as a megahertz or as high as a few hundred gigahertz. The top side of the specimen would be coupled to an object that would have a flat (when not vibrating) top surface and that would serve as the acoustical analog of an optical medium (in effect, an acoustical "optic").

  20. Acoustic rainbow trapping by coiling up space

    KAUST Repository

    Ni, Xu

    2014-11-13

    We numerically realize the acoustic rainbow trapping effect by tapping an air waveguide with space-coiling metamaterials. Due to the high refractive-index of the space-coiling metamaterials, our device is more compact compared to the reported trapped-rainbow devices. A numerical model utilizing effective parameters is also calculated, whose results are consistent well with the direct numerical simulation of space-coiling structure. Moreover, such device with the capability of dropping different frequency components of a broadband incident temporal acoustic signal into different channels can function as an acoustic wavelength division de-multiplexer. These results may have potential applications in acoustic device design such as an acoustic filter and an artificial cochlea.

  1. Acoustical components of the Orpheum Theatre renovation

    Science.gov (United States)

    Conant, David A.

    2002-05-01

    The before and after acoustically-important listening conditions and measurements are described for a $14.2 million restoration and renovation of this 1,400-seat grand 1929 Movie Palace-at one time the tallest building in Phoenix. Great care was taken to restore all the acoustically good parts of the original design and to subtly modify the acoustically-troublesome parts (including severely focusing dome and sidewalls) so they looked the same but performed properly. A beautiful playhouse was achieved in 1997 with fine, fixed acoustics and conventional audio reinforcement, a surrounding Italian village, plenty of gilt, moving clouds and sunsets overhead. Today, the venue successfully hosts shows from performance art to ballet to jazz. It was not intended (acoustically) to serve classical music but does so on occasion.

  2. Microfabricated bulk wave acoustic bandgap device

    Science.gov (United States)

    Olsson, Roy H.; El-Kady, Ihab F.; McCormick, Frederick; Fleming, James G.; Fleming, Carol

    2010-06-08

    A microfabricated bulk wave acoustic bandgap device comprises a periodic two-dimensional array of scatterers embedded within the matrix material membrane, wherein the scatterer material has a density and/or elastic constant that is different than the matrix material and wherein the periodicity of the array causes destructive interference of the acoustic wave within an acoustic bandgap. The membrane can be suspended above a substrate by an air or vacuum gap to provide acoustic isolation from the substrate. The device can be fabricated using microelectromechanical systems (MEMS) technologies. Such microfabricated bulk wave phononic bandgap devices are useful for acoustic isolation in the ultrasonic, VHF, or UHF regime (i.e., frequencies of order 1 MHz to 10 GHz and higher, and lattice constants of order 100 .mu.m or less).

  3. Unexpectedly Large Surface Gravities for Acoustic Horizons?

    CERN Document Server

    Liberati, S; Visser, M; Liberati, Stefano; Sonego, Sebastiano; Visser, Matt

    2000-01-01

    Acoustic black holes are fluid dynamic analogs of general relativistic black holes, wherein the behaviour of sound waves in a moving fluid acts as an analog for scalar fields propagating in a gravitational background. Acoustic horizons possess many of the properties more normally associated with the event horizons of general relativity, up to and including Hawking radiation. They have received much attention because it would seem to be much easier to experimentally create an acoustic horizon than to create an event horizon. We wish to point out some potential difficulties (and opportunities) in actually setting up an experiment that possesses an acoustic horizon. We show that in zero-viscosity, stationary fluid flow with generic boundary conditions, the creation of an acoustic horizon is accompanied by a formally infinite ``surface gravity'', and a formally infinite Hawking flux. Only by applying a suitable non-constant external body force, and for very specific boundary conditions on the flow, can these quan...

  4. 30th International Acoustical Imaging Symposium

    CERN Document Server

    Jones, Joie; Lee, Hua

    2011-01-01

    The International Symposium on Acoustical Imaging is a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. This interdisciplinary Symposium has been taking place every two years since 1968. In the course of the years the proceedings volumes in the Acoustical Imaging Series have become a reference for cutting-edge research in the field. In 2009 the 30th International Symposium on Acoustical Imaging was held in Monterey, CA, USA, March 1-4. Offering both a broad perspective on the state-of-the-art as well as  in-depth research contributions by the specialists in the field, this Volume 30 in the Series contains an excellent collection of forty three papers presented in five major categories: Biomedical Imaging Acoustic Microscopy Non-Destructive Evaluation Systems Analysis Signal Analysis and Image Processing Audience Researchers in medical imaging and biomedical instrumentation experts.

  5. Acoustic propagation in a rigid torus

    Science.gov (United States)

    El-Raheb, M.; Wagner, P.

    1982-01-01

    The acoustic propagation in a rigid torus is analyzed using a Green's function method. Three types of surface elements are developed; a flat quadrilateral element used in modeling polygonal cavities, a curved conical element appropriate for surfaces with one curvature, and a toroidal element developed for such doubly curved surfaces as the torus. Curved elements are necessary since the acoustic pressure is sensitive to slope discontinuities between consecutive surface elements especially near cavity resonances. The acoustic characteristics of the torus are compared to those of a bend of square cross section for a frequency range that includes the transverse acoustic resonance. Two equivalences between the different sections are tested; the first conserves curvature and cross-sectional dimension while the second matches transverse resonance and duct volume. The second equivalence accurately matches the acoustic characteristics of the torus up to the cutoff frequency corresponding to a mode with two circumferential waves.

  6. Eigenvalue solution to the electron-collisional effect on ion-acoustic and entropy waves

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The linearized electron Fokker-Planck and cold-ion fluid equations are solved as an eigenvalue problem in the quasineutral limit for ionization state,Z=1,8,and 64 for ion-acoustic and entropy waves.The perturbed electron distribution function is written as a moment expansion of eigenvectors,and is used to compute collisionality-dependence macroscopic quantities in the plasma such as the generalized specific heat ratio,and the electron thermal conductivity.

  7. Heating systems for heating subsurface formations

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Scott Vinh (Houston, TX); Vinegar, Harold J. (Bellaire, TX)

    2011-04-26

    Methods and systems for heating a subsurface formation are described herein. A heating system for a subsurface formation includes a sealed conduit positioned in an opening in the formation and a heat source. The sealed conduit includes a heat transfer fluid. The heat source provides heat to a portion of the sealed conduit to change phase of the heat transfer fluid from a liquid to a vapor. The vapor in the sealed conduit rises in the sealed conduit, condenses to transfer heat to the formation and returns to the conduit portion as a liquid.

  8. Hydride heat pump with heat regenerator

    Science.gov (United States)

    Jones, Jack A. (Inventor)

    1991-01-01

    A regenerative hydride heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system. A series of at least four canisters containing a lower temperature performing hydride and a series of at least four canisters containing a higher temperature performing hydride is provided. Each canister contains a heat conductive passageway through which a heat transfer fluid is circulated so that sensible heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

  9. Millimeter waves: acoustic and electromagnetic.

    Science.gov (United States)

    Ziskin, Marvin C

    2013-01-01

    This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It summarizes my research activities in acoustic and electromagnetic millimeter waves over the past 47 years. My earliest research involved acoustic millimeter waves, with a special interest in diagnostic ultrasound imaging and its safety. For the last 21 years my research expanded to include electromagnetic millimeter waves, with a special interest in the mechanisms underlying millimeter wave therapy. Millimeter wave therapy has been widely used in the former Soviet Union with great reported success for many diseases, but is virtually unknown to Western physicians. I and the very capable members of my laboratory were able to demonstrate that the local exposure of skin to low intensity millimeter waves caused the release of endogenous opioids, and the transport of these agents by blood flow to all parts of the body resulted in pain relief and other beneficial effects. Copyright © 2012 Wiley Periodicals, Inc.

  10. An introduction to acoustic emission

    Science.gov (United States)

    Scruby, C. B.

    1987-08-01

    The technique of acoustic emission (AE) uses one or more sensors to 'listen' to a wide range of events that may take place inside a solid material. Depending on the source of this high frequency sound, there are broadly three application areas: structural testing and surveillance, process monitoring and control, and materials characterization. In the first case the source is probably a defect which radiates elastic waves as it grows. Provided these waves are detectable, AE can be used in conjunction with other NDT techniques to assess structural integrity. Advances in deterministic and statistical analysis methods now enable data to be interpreted in greater detail and with more confidence than before. In the second area the acoustic signature of processes is monitored, ranging from for instance the machining of metallic components to the mixing of foodstuffs, and changes correlated with variations in the process, with the potential for feedback and process control. In the third area, AE is used as an additional diagnostic technique for the study of, for instance, fracture, because it gives unique dynamic information on defect growth.

  11. Acoustic image-processing software

    Science.gov (United States)

    Several algorithims that display, enhance and analyze side-scan sonar images of the seafloor, have been developed by the University of Washington, Seattle, as part of an Office of Naval Research funded program in acoustic image analysis. One of these programs, PORTAL, is a small (less than 100K) image display and enhancement program that can run on MS-DOS computers with VGA boards. This program is now available in the public domain for general use in acoustic image processing.PORTAL is designed to display side-scan sonar data that is stored in most standard formats, including SeaMARC I, II, 150 and GLORIA data. (See image.) In addition to the “standard” formats, PORTAL has a module “front end” that allows the user to modify the program to accept other image formats. In addition to side-scan sonar data, the program can also display digital optical images from scanners and “framegrabbers,” gridded bathymetry data from Sea Beam and other sources, and potential field (magnetics/gravity) data. While limited in image analysis capability, the program allows image enhancement by histogram manipulation, and basic filtering operations, including multistage filtering. PORTAL can print reasonably high-quality images on Postscript laser printers and lower-quality images on non-Postscript printers with HP Laserjet emulation. Images suitable only for index sheets are also possible on dot matrix printers.

  12. Impact of Acoustic Standing Waves on Structural Responses: Reverberant Acoustic Testing (RAT) vs. Direct Field Acoustic Testing (DFAT)

    Science.gov (United States)

    Kolaini, Ali R.; Doty, Benjamin; Chang, Zensheu

    2012-01-01

    Loudspeakers have been used for acoustic qualification of spacecraft, reflectors, solar panels, and other acoustically responsive structures for more than a decade. Limited measurements from some of the recent speaker tests used to qualify flight hardware have indicated significant spatial variation of the acoustic field within the test volume. Also structural responses have been reported to differ when similar tests were performed using reverberant chambers. To address the impact of non-uniform acoustic field on structural responses, a series of acoustic tests were performed using a flat panel and a 3-ft cylinder exposed to the field controlled by speakers and repeated in a reverberant chamber. The speaker testing was performed using multi-input-single-output (MISO) and multi-input-multi-output (MIMO) control schemes with and without the test articles. In this paper the spatial variation of the acoustic field due to acoustic standing waves and their impacts on the structural responses in RAT and DFAT (both using MISO and MIMO controls for DFAT) are discussed in some detail.

  13. Heat transfer

    CERN Document Server

    Jorge, Kubie; Thomas, Grassie

    2012-01-01

    A core task of engineers is to analyse energy related problems. The analytical treatment is usually based on principles of thermodynamics, fluid mechanics and heat transfer, but is increasingly being handled computationally.This unique resource presents a practical textbook, written for both undergraduates and professionals, with a series of over 60 computer workbooks on an accompanying CD.The book emphasizes how complex problems can be deconstructed into a series of simple steps. All thermophysical property computations are illustrated using diagrams within text and on the compani

  14. Heat pipes

    CERN Document Server

    Dunn, Peter D

    1982-01-01

    A comprehensive, up-to-date coverage of the theory, design and manufacture of heat pipes and their applications. This latest edition has been thoroughly revised, up-dated and expanded to give an in-depth coverage of the new developments in the field. Significant new material has been added to all the chapters and the applications section has been totally rewritten to ensure that topical and important applications are appropriately emphasised. The bibliography has been considerably enlarged to incorporate much valuable new information. Thus readers of the previous edition, which has established

  15. Low temperature nuclear heat

    Energy Technology Data Exchange (ETDEWEB)

    Kotakorpi, J.; Tarjanne, R. (comps.)

    1977-08-01

    The meeting was concerned with the use of low grade nuclear heat for district heating, desalination, process heat, and agriculture and aquaculture. The sessions covered applications and demand, heat sources, and economics.

  16. Regenerative Hydride Heat Pump

    Science.gov (United States)

    Jones, Jack A.

    1992-01-01

    Hydride heat pump features regenerative heating and single circulation loop. Counterflow heat exchangers accommodate different temperatures of FeTi and LaNi4.7Al0.3 subloops. Heating scheme increases efficiency.

  17. Heat-Related Illnesses

    Medline Plus

    Full Text Available ... Emergencies A-Z Share this! Home » Emergency 101 Heat-Related Illnesses Dr. Glenn Mitchell , Emergency physician at ... about heat cramps and heat stroke and exhaustion. Heat Cramps Symptoms include muscle spasms, usually in the ...

  18. Regenerative Hydride Heat Pump

    Science.gov (United States)

    Jones, Jack A.

    1992-01-01

    Hydride heat pump features regenerative heating and single circulation loop. Counterflow heat exchangers accommodate different temperatures of FeTi and LaNi4.7Al0.3 subloops. Heating scheme increases efficiency.

  19. Thermo-acoustic instabilities in lean premixed swirl-stabilized combustion and their link to acoustically coupled and decoupled flame macrostructures

    KAUST Repository

    Taamallah, Soufien

    2015-01-01

    © 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved. We investigate the onset of thermo-acoustic instabilities and their link to the mean flame configurations - or macrostructures - under acoustically coupled and decoupled conditions. Methane-hydrogen mixtures are used to explore the role of the fuel in changing the flame macrostructure, as determined by chemilumi-nescence, as the equivalence ratio (φ) varies. We observe four different configurations: a columnar flame (I); a bubble-columnar flame (II); a single conical flame (III); and a double conical flame (IV). We also observe different thermo-acoustic modes in the lean regime investigated, φ ∈ [0.5-0.75], that correspond to different flame configurations. By changing the combustor length without affecting the underlying flow, the resonant modes of the combustor are shifted to higher frequencies allowing for the decoupling of heat release fluctuations and the acoustic field over a range of equivalence ratio. We find that the same flame macrostructures observed in the long, acoustically coupled combustor arise in the short, acoustically decoupled combustor and transition at similar equivalence ratios in both combustors. The onset of the first fully unstable mode in the long combustor occurs at similar equivalence ratio as the flame transition from configuration III to IV. In the acoustically decoupled case, this transition occurs gradually starting with the intermittent appearance of a flame in the outer recirculation zone (ORZ). Spectral analysis of this phenomenon, referred to as "ORZ flame flickering" shows the existence of an unsteady event occurring over a narrow frequency band centered around 28 Hz along with a weaker broadband region at lower frequency in the range [1-10] Hz. The tone at 28 Hz is shown to be associated with the azimuthal advection of the flame by the outer recirculation zone flow. Changes in the fuel composition, by adding hydrogen (up to 20%), do not

  20. A membrane-type acoustic metamaterial with adjustable acoustic properties

    Science.gov (United States)

    Langfeldt, F.; Riecken, J.; Gleine, W.; von Estorff, O.

    2016-07-01

    A new realization of a membrane-type acoustic metamaterial (MAM) with adjustable sound transmission properties is presented. The proposed design distinguishes itself from other realizations by a stacked arrangement of two MAMs which is inflated using pressurized air. The static pressurization leads to large nonlinear deformations and, consequently, geometrical stiffening of the MAMs which is exploited to adjust the eigenmodes and sound transmission loss of the structure. A theoretical analysis of the proposed inflatable MAM design using numerical and analytical models is performed in order to identify two important mechanisms, namely the shifting of the eigenfrequencies and modal residuals due to the pressurization, responsible for the transmission loss adjustment. Analytical formulas are provided for predicting the eigenmode shifting and normal incidence sound transmission loss of inflated single and double MAMs using the concept of effective mass. The investigations are concluded with results from a test sample measurement inside an impedance tube, which confirm the theoretical predictions.