WorldWideScience

Sample records for acoustic properties

  1. 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.

  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. The Acoustical Properties of Indonesian Hardwood Species

    Directory of Open Access Journals (Sweden)

    Tarcisius Rio Mardikanto

    2012-08-01

    Full Text Available The acoustical properties of four Indonesian tropical hardwood species were evaluated in this study. The objectives of this study were to determine acoustical parameters e.g. logarithmic decrement, sound absorption, sound velocity as well as density and wood stiffness; and to evaluate the potential of those species for acoustical purposes. Sonokeling (Dalbergia latifolia, Mahoni (Swietenia mahagony, Acacia (Acacia mangium and Manii wood (Maesopsis eminii were selected in this research. Three different cutting plane patterns of sawn timber (quarter-sawn, flat-sawn, and plain-sawn were converted into small specimens. The methods for determining acoustical properties were longitudinal vibration testing and time of flight of ultrasonic wave method. The result showed no significant difference (α=0.05 of acoustical properties in logarithmic decrement, sound absorption, and ultrasonic velocity means on quarter-sawn, flat-sawn, and plain-sawn for all wood species tested. We found that Mahoni and Sonokeling had good acoustical properties of logarithmic decrement, ultrasonic wave velocity, and ratio of wood stiffness to wood density; and is preferred for crafting musical instruments. Acacia and Manii woods are recommended for developing acoustic panels in building construction because those species possess higher sound absorption values.

  4. Acoustic properties of aluminium foams

    Directory of Open Access Journals (Sweden)

    García, L. E.

    2008-09-01

    Full Text Available The article discusses normal incidence sound absorption by aluminium foam manufactured with powder metallurgy technology. Aluminium foams with different surface morphologies were obtained by varying the type of precursor and adding filler materials during the foaming process. The sound absorption coefficients found for these aluminium foams were compared to the coefficient for commercial foams marketed under the name ALPORAS. The effect of foam thickness on the absorption coefficient was studied for each sample prepared. The combination of good acoustic and mechanical properties makes aluminium foams particularly attractive products. The study included an analysis of the effect of 2-, 5- and 10-cm air gaps on the sound absorption coefficient. The results showed that such gaps, which are routinely used in construction to reduce the reverberation period in indoor premises, raised the low frequency absorption coefficient significantly. This increase was found to depend on aluminium foam density and thickness and the depth of the air gap. In this same line, we have investigated the absorption coefficient of the aluminium foams combined with a mineral fiber panel.Se presenta un estudio del coeficiente de absorción acústica a incidencia normal de espumas de aluminio fabricadas mediante la técnica pulvimetalúrgica. Se fabricaron espumas de aluminio de distinta morfología superficial variando el tipo de precursor y usando materiales de relleno durante el proceso de espumación. Se muestra un estudio comparativo del coeficiente de absorción acústica de las espumas de aluminio fabricadas y las espumas comerciales conocidas como ALPORAS. Para cada muestra fabricada se estudió la influencia del espesor sobre el valor del coeficiente de absorción.El atractivo de las espumas de aluminio radica en que en ellas se combinan interesantes propiedades acústicas y mecánicas. Se analizó el efecto de una cámara de aire de 2, 5 y 10 cm de anchura sobre el

  5. The structural acoustic properties of stiffened shells

    DEFF Research Database (Denmark)

    Luan, Yu

    2008-01-01

    . This is important when a number of stiffened plates are combined in a complicated structure composed of many plates. However, whereas the equivalent plate theory is well established there is no similar established theory for stiffened shells. This paper investigates the mechanical and structural acoustic properties...... of curved shells with stiffening ribs. Finite element simulations and experimental data will be compared and discussed....

  6. 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.

  7. Noninvasive fluid property measurements using acoustic methods.

    Science.gov (United States)

    Forbush, Michael; Chow, Humphrey; Chiao, James; Rose, Andrew

    2007-03-01

    The properties of a fluid are normally determined using invasive methods. These methods may lead to possibly contaminating or consuming the sample. When only very small amounts of a valuable sample exist, noninvasive measurement methods are preferred. The properties of fluids can then be used to deduce additional properties based on known relationships. In one case, the surface tension of a fluid may be used to determine the concentration of a fluid. The authors describe a measurement technique involving excitation of the surface of the fluid and the measurement of its response. An acoustic wave is used to both excite and monitor the surface of the liquid. This technique is used to determine the concentration of DMSO and water in solution, and the result determines the amount of fluid needed to deliver an accurate amount of solute in solution.

  8. Properties of Materials Using Acoustic Waves.

    Science.gov (United States)

    1984-10-01

    CLASSiFICATIOO OF THIS PAGIR elM. DMe Eatae" to nonlinear acoustics which should permit us to cast problems with geometric and other complexities into a...on the kinetics of chemical reactions . 5. New theoretical approaches in nonlinear acoustics (R.M. McGowan and Professor B.-T. Chu) We are working to...of water and methanol was compared with the theoretical predictions given by Marston’s theory and the simplified model (Hsu 1983). This set of data

  9. Models for acoustical properties of green roof materials

    OpenAIRE

    2011-01-01

    To predict the acoustical effects of green roof structures it is necessary to be able to model the acoustical properties of their materials including gravel. For time domain calculations it is convenient to use the phenomenological model due to Zwikker and Kosten. However this phenomenological model is related to a low frequency/high flow resistivity approximation of more ‘exact’ identical pore models. The results of fitting predictions to short range level difference data and to impedance da...

  10. Broadband acoustic properties of a murine skull.

    Science.gov (United States)

    Estrada, Héctor; Rebling, Johannes; Turner, Jake; Razansky, Daniel

    2016-03-07

    It has been well recognized that the presence of a skull imposes harsh restrictions on the use of ultrasound and optoacoustic techniques in the study, treatment and modulation of the brain function. We propose a rigorous modeling and experimental methodology for estimating the insertion loss and the elastic constants of the skull over a wide range of frequencies and incidence angles. A point-source-like excitation of ultrawideband acoustic radiation was induced via the absorption of nanosecond duration laser pulses by a 20 μm diameter microsphere. The acoustic waves transmitted through the skull are recorded by a broadband, spherically focused ultrasound transducer. A coregistered pulse-echo ultrasound scan is subsequently performed to provide accurate skull geometry to be fed into an acoustic transmission model represented in an angular spectrum domain. The modeling predictions were validated by measurements taken from a glass cover-slip and ex vivo adult mouse skulls. The flexible semi-analytical formulation of the model allows for seamless extension to other transducer geometries and diverse experimental scenarios involving broadband acoustic transmission through locally flat solid structures. It is anticipated that accurate quantification and modeling of the skull transmission effects would ultimately allow for skull aberration correction in a broad variety of applications employing transcranial detection or transmission of high frequency ultrasound.

  11. Acoustic Oscillation Properties of Active Region 12193

    Science.gov (United States)

    Monsue, Teresa; Pesnell, William D.; Hill, Frank

    2017-08-01

    Solar flares are dynamic objects occurring randomly and yet unannounced in nature. In order to find an efficient detection method, we require a greater breadth of knowledge of the system. One path to such a method is to observe the solar atmosphere in a region around a flare in different wavelengths of light and acoustic frequency bands. This provides information from different altitudes in the solar atmosphere and allows us to study the temporal evolution of each altitude through the flaring event. A more complete understanding of the time evolution may lead to yet undiscovered precursors of the flare. In this project, we study Active Region 12192 using acoustic observations near an X3 flare occurring on October 24, 2014 at 21:41UT. Our wavelet analysis utilizes time series data to create Fourier power spectra of individual pixels spatially resolved around the flare region, to study the frequency bands. In order to study the power distribution in regions around the flare and to search for any correlation we apply several methods. One method we partition sub-regions in our main flaring region and take a survey of the oscillations for each frequency band within power maps. Another method we average the FFT to take measurements within the p-modes (2-4 mHz) and chromospheric (4-6 mHz) frequencies. The application of these methods should be able to get us closer to tracking waveforms within power maps.

  12. Evaluation of the acoustic and non-acoustic properties of sound absorbing materials using a three-microphone impedance tube

    CERN Document Server

    Doutres, Olivier; Atalla, Noureddine; Panneton, Raymond; 10.1016/j.apacoust.2010.01.007

    2010-01-01

    This paper presents a straightforward application of an indirect method based on a three-microphone impedance tube setup to determine the non-acoustic properties of a sound absorbing porous material. First, a three-microphone impedance tube technique is used to measure some acoustic properties of the material (i.e., sound absorption coefficient, sound transmission loss, effective density and effective bulk modulus) regarded here as an equivalent fluid. Second, an indirect characterization allows one to extract its non-acoustic properties (i.e., static airflow resistivity, tortuosity, viscous and thermal characteristic lengths) from the measured effective properties and the material open porosity. The procedure is applied to four different sound absorbing materials and results of the characterization are compared with existing direct and inverse methods. Predictions of the acoustic behavior using an equivalent fluid model and the found non-acoustic properties are in good agreement with impedance tube measureme...

  13. Nucleation, growth and acoustic properties of thin film diamond

    CERN Document Server

    Whitfield, M D

    1999-01-01

    emission spectroscopy has been used to study the influence of substrate bias on the microwave plasma during diamond nucleation. Surface acoustic wave (SAW) devices have recently emerged as promising near term applications for currently available CVD diamond however little is known about the propagation of acoustic waves in this material; a detailed study of the influence of film characteristics on acoustic propagation in free standing CVD diamond films has been undertaken using the techniques of laser ultrasonic analysis. The unusual combination of extreme properties possessed by diamond could benefit a wide range of applications. Thus far practical utilisation of this material has remained difficult and consequently limited; natural and synthetic crystals are unsuitable forms for many uses; particularly electronic applications which ideally require large area, single crystal substrates. Emerging CVD methods for the growth of thin film diamond offer a practical alternative; although nucleation on non-diamond ...

  14. Acoustic Properties of Innovative Material from Date Palm Fibre

    Directory of Open Access Journals (Sweden)

    Lamyaa Abd AL-Rahman

    2012-01-01

    Full Text Available Problem statement: An organic material is one of the major requirements to improve living environment and the invention of materials need to consider for the best solution. This study presents an experimental investigation on pure porous from Date Palm Fibre (DPF. The effectiveness of sound absorbers depends on structural architecture of this material. This study was conducted to examine the potential of using date palm fibre as sound absorber. The effects of porous layer thicknesses, densities and compression on Acoustic Absorption Coefficient (AAC of sound absorber using date palm fibre were studied. Approach: Rigid frame Johnson-Allard Model for various sample thicknesses was used in this study. The measurements were conducted in impedance tube on normal incidence acoustic absorption. The date palm fibre was mixed with latex which used for physical treatment on this material. Acoustic absorption behaviour of a porous material with different thicknesses was studied as well as samples with same thickness but different densities. In addition, samples with same properties but different period of compression time were inspected. The tests were in accordance to ISO 10534-2 and ASTM E1050-98 international standards for Acoustic Absorption Coefficient (AAC. Results: The experimental data indicates that two peak values of AAC is 0.93 at 1356Hz for sample with 50 mm thickness, also the AAC at high frequency for same thickness is 0.99 at 4200-4353 Hz that means able to improve acoustic absorption coefficient at low and high frequencies with significant increasing. Meanwhile, another experimental results were acquired for AAC of date palm fibre, with samples thicknesses of 35 mm at different densities .The results show that denser sample (11 Kg m-3 has higher AAC value of 0.83 at 1934- 2250 Hz as compared to less dense sample (9.92 Kg m-3 with AAC value 0.84 at 2443-2587 Hz . Conclusion: Acoustic absorption coefficient AAC of date palm fibre was

  15. The influence of clay minerals on acoustic properties of sandstones

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Olav

    1997-12-31

    This thesis aims to provide better understanding of the relationship between the acoustic properties and the petrophysical/mineralogical properties in sand-prone rock. It emphasizes the influence of clay minerals. The author develops a method to deposit clay minerals/mineral aggregates in pore space of a rigid rock framework. Kaolinite aggregates were flushed into porous permeable Bentheimer sandstone to evaluate the effect of pore filling minerals on porosity, permeability and acoustic properties. The compressional velocity was hardly affected by the clay content and it was found that the effect of minor quantities of pore filling minerals may be acoustically modelled as an ideal suspension, where the pore fluid bulk modulus is modified by the bulk modulus of the clay minerals. The influence of clays on acoustic velocities in petroleum reservoir rocks was investigated through ultrasonic measurements of compressional- and shear-waves on core material from reservoir and non-reservoir units on the Norwegian Continental Shelf. The measured velocities decrease as the porosity increases, but are not strongly dependent on the clay content. The measured velocities are less dependent on the petrophysical and lithological properties than indicated by previous authors and published mathematical models, and stiffness reduction factors are introduced in two of the models to better match the data. Velocities are estimated along the wellbores based on non-sonic well logs and reflect well the actual sonic log well measurements. In some wells the compressional velocity cannot be modelled correctly by the models suggested. Very high compressional wave anisotropy was measured in the dry samples at atmospheric conditions. As the samples were saturated, the anisotropy was reduced to a maximum of about 30% and decreases further upon pressurization. Reservoir rocks retrieved from 2500 m are more stress dependent than those retrieved from less than 200 m depth. 168 refs., 117 figs., 24

  16. Acoustical properties of nonwoven fiber network structures

    Science.gov (United States)

    Tascan, Mevlut

    Sound insulation is one of the most important issues for the automotive and building industries. Because they are porous fibrous structures, textile materials can be used as sound insulating and sound absorbing materials. Very high-density materials such as steel can insulate sound very effectively but these rigid materials reflect most of the sound back to the environment, causing sound pollution. Additionally, because high-density, rigid materials are also heavy and high cost, they cannot be used for sound insulation for the automotive and building industries. Nonwoven materials are more suitable for these industries, and they can also absorb sound in order to decrease sound pollution in the environment. Therefore, nonwoven materials are one of the most important materials for sound insulation and absorption applications materials. Insulation and absorption properties of nonwoven fabrics depend on fiber geometry and fiber arrangement within the fabric structure. Because of their complex structure, it is very difficult to define the microstructure of nonwovens. The structure of nonwovens only has fibers and voids that are filled by air. Because of the complexity of fiber-void geometry, there is still not a very accurate theory or model that defines the structural arrangement. A considerable amount of modeling has been reported in literature [1--19], but most models are not accurate due to the assumptions made. Voids that are covered by fibers are called pores in nonwoven structures and their geometry is very important, especially for the absorption properties of nonwovens. In order to define the sound absorption properties of nonwoven fabrics, individual pore structure and the number of pores per unit thickness of the fabric should be determined. In this research, instead of trying to define pores, the properties of the fibers are investigated and the number of fibers per volume of fabric is taken as a parameter in the theory. Then the effect of the nonwoven

  17. Correlation of mechanical properties with the acoustic properties in case of an experimental white cast iron

    Science.gov (United States)

    Gȋrneţ, A.; Stanciu, S.; Chicet, D.; Axinte, M.; Goanţă, V.

    2016-08-01

    The general and traditional opinion regarding the materials used to build bells, musical instruments or sound transmitters is that those materials must be only from the bronze alloyed with tin category. In order to approach this idea from a scientific point of view, the materials with acoustic properties must be analyzed starting from the physical theory and experimental determination that sound travels only through bodies with elastic properties. It has been developed an experimental white cast iron, medium alloyed with Cr and Ni, in order to obtain a material with special acoustic properties. There were determined on specific samples: the vibration damping capacity, the unit energy, the tensile strength and elasticity modulus. These properties were correlated with the properties of other known acoustic materials.

  18. The acoustic properties of Salpa thompsoni

    KAUST Repository

    Wiebe, Peter H.

    2009-12-01

    Aggregations of the salp Salpa thompsoni were encountered during the Antarctic krill and ecosystem-studies cruise on the RV "G.O. Sars" from 19 February to 27 March 2008. The salp\\'s in situ target strength (TS), size, number of individuals in aggregate chains, and chain angle of orientation were determined. Shipboard measurements were made of Salpa thompsoni\\'s material properties. Individual aggregates were mostly 45.5-60.6 mm in mean length; relatively rare solitaries were ∼100 mm. Chains ranged from 3 to at least 121 individuals, and in surface waters (<20 m), they showed no preferred angle of orientation. Sound-speed contrast (h) ranged from 1.0060 to 1.0201 and density contrast (g) estimates between 1.0000 and 1.0039. The in situ TS distributions peaked between-75 and - 76 dB at 38 kHz, with a secondary peak at approximately - 65 dB. TS ranged between-85 and - 65 dB at 120 and 200 kHz and peaked around-74 dB. The measured in situ TS of salps reasonably matched the theoretical scattering-model predictions based on multi-individual chains. The backscattering from aggregate salps gives rise to TS values that can be similar to krill and other zooplankton with higher density and sound-speed contrasts. © 2009 International Council for the Exploration of the Sea.

  19. Acoustics of fish shelters: frequency response and gain properties.

    Science.gov (United States)

    Lugli, Marco

    2012-11-01

    Many teleosts emit sounds from cavities beneath stones and other types of submerged objects, yet the acoustical properties of fish shelters are virtually unexplored. This study examines the gain properties of shelters commonly used by Mediterranean gobies as hiding places and/or nest sites in the field (flat stones, shells belonging to five bivalve species), or within aquarium tanks (tunnel-shaped plastic covers, concrete blocks, concrete cylinder pipe, halves of terracotta flower pots). All shelters were acoustically stimulated using a small underwater buzzer, placed inside or around the shelter to mimic a fish calling from the nest site, and different types of driving stimuli (white noise, pure tones, and artificial pulse trains). Results showed the presence of significant amplitude gain (3-18 dB) at frequencies in the range 100-150 Hz in all types of natural shelters but one (Mytilus), terracotta flower pots, and concrete blocks. Gain was higher for stones and artificial shelters than for shells. Gain peak amplitude increased with the weight of stones and shells. Conclusions were verified by performing analogous acoustical tests on flat stones in the stream. Results draw attention to the use of suitable shelters for proper recording of sounds produced by fishes kept within laboratory aquaria.

  20. Moving to the Speed of Sound: Context Modulation of the Effect of Acoustic Properties of Speech

    Science.gov (United States)

    Shintel, Hadas; Nusbaum, Howard C.

    2008-01-01

    Suprasegmental acoustic patterns in speech can convey meaningful information and affect listeners' interpretation in various ways, including through systematic analog mapping of message-relevant information onto prosody. We examined whether the effect of analog acoustic variation is governed by the acoustic properties themselves. For example, fast…

  1. The Voice of Emotion: Acoustic Properties of Six Emotional Expressions.

    Science.gov (United States)

    Baldwin, Carol May

    Studies in the perceptual identification of emotional states suggested that listeners seemed to depend on a limited set of vocal cues to distinguish among emotions. Linguistics and speech science literatures have indicated that this small set of cues included intensity, fundamental frequency, and temporal properties such as speech rate and duration. Little research has been done, however, to validate these cues in the production of emotional speech, or to determine if specific dimensions of each cue are associated with the production of a particular emotion for a variety of speakers. This study addressed deficiencies in understanding of the acoustical properties of duration and intensity as components of emotional speech by means of speech science instrumentation. Acoustic data were conveyed in a brief sentence spoken by twelve English speaking adult male and female subjects, half with dramatic training, and half without such training. Simulated expressions included: happiness, surprise, sadness, fear, anger, and disgust. The study demonstrated that the acoustic property of mean intensity served as an important cue for a vocal taxonomy. Overall duration was rejected as an element for a general taxonomy due to interactions involving gender and role. Findings suggested a gender-related taxonomy, however, based on differences in the ways in which men and women use the duration cue in their emotional expressions. Results also indicated that speaker training may influence greater use of the duration cue in expressions of emotion, particularly for male actors. Discussion of these results provided linkages to (1) practical management of emotional interactions in clinical and interpersonal environments, (2) implications for differences in the ways in which males and females may be socialized to express emotions, and (3) guidelines for future perceptual studies of emotional sensitivity.

  2. Acoustical, morphological and optical properties of oral rehydration salts (ORS)

    Energy Technology Data Exchange (ETDEWEB)

    George, Preetha Mary, E-mail: preethageoti@gmail.com, E-mail: jayakumars030@gmail.com; Divya, P. [Department of Physics, Dr M.G.R Educational and Research Institute University Chennai- (India); Jayakumar, S., E-mail: preethageoti@gmail.com, E-mail: jayakumars030@gmail.com; Subhashree, N. S. [Department of Physics, RKM Vivekananda College, Chennai-600004 (India); Ahmed, M. Anees [Department of Physics, New College, Chennai (India)

    2015-06-24

    Ultrasonic velocity, density and viscosity were measured in different concentrations of oral rehydration salts (ORS) at room temperature 303 k. From the experimental data other related thermodynamic parameters, viz adiabatic compressibility, intermolecular free length, acoustic impedence, relaxation time are calculated. The experimental data were discussed in the light of molecular interaction existing in the liquid mixtures. The results have been discussed in terms of solute-solvent interaction between the components. Structural characterization is important for development of new material. The morphology, structure and grain size of the samples are investigated by SEM. The optical properties of the sample have been studied using UV Visible spectroscopy.

  3. The mechanical and acoustic properties of two-dimensional pentamode metamaterials with different structural parameters

    Science.gov (United States)

    Cai, Xuan; Wang, Lei; Zhao, Zhigao; Zhao, Aiguo; Zhang, Xiangdong; Wu, Tao; Chen, Hong

    2016-09-01

    The effective mechanical and acoustic properties of two-dimensional pentamode metamaterials (PMs) with different structural parameters are investigated in this paper. It is found that with varying structural parameters, the effective bulk modulus and density remain constant as the same as those of water, while the figure of merit, i.e., the ratio of the bulk modulus to the shear modulus (B/G) gradually increases due to the decrease of the shear modulus. However, full wave simulations reveal that with the increase of B/G, the acoustic scattering becomes more and more intense, which indicates that the acoustic properties of pentamode metamaterials gradually deviate from those of water. These anomalous acoustic behaviors are proposed to arise from the existence of the bending modes in pentamode microstructures. Our results show that for pentamode metamaterials, the mechanical properties cannot be simply translated to their acoustic properties, and the structural parameters affect the mechanical and acoustic properties in much different ways.

  4. Acoustic and elastic properties of Sn(2)P(2)S(6) crystals.

    Science.gov (United States)

    Mys, O; Martynyuk-Lototska, I; Grabar, A; Vlokh, R

    2009-07-01

    We present the results concerned with acoustic and elastic properties of Sn(2)P(2)S(6) crystals. The complete matrices of elastic stiffness and compliance coefficients are determined in both the crystallographic coordinate system and the system associated with eigenvectors of the elastic stiffness tensor. The acoustic slowness surfaces are constructed and the propagation and polarization directions of the slowest acoustic waves promising for acousto-optic interactions are determined on this basis. The acoustic obliquity angle and the deviation of polarization of the acoustic waves from purely transverse or longitudinal states are quantitatively analysed.

  5. On the Acoustic Properties of Vaporized Submicron Perfluorocarbon Droplets

    NARCIS (Netherlands)

    Reznik, Nikita; Lajoinie, Guillaume; Shpak, Oleksandr; Gelderblom, Erik C.; Williams, Ross; Jong, de Nico; Versluis, Michel; Burns, Peter N.

    2014-01-01

    The acoustic characteristics of microbubbles created from vaporized submicron perfluorocarbon droplets with fluorosurfactant coating are examined. Utilizing ultra-high-speed optical imaging, the acoustic response of individual microbubbles to low-intensity diagnostic ultrasound was observed on clini

  6. Monitoring polymer properties using shear horizontal surface acoustic waves.

    Science.gov (United States)

    Gallimore, Dana Y; Millard, Paul J; Pereira da Cunha, Mauricio

    2009-10-01

    Real-time, nondestructive methods for monitoring polymer film properties are increasingly important in the development and fabrication of modern polymer-containing products. Online testing of industrial polymer films during preparation and conditioning is required to minimize material and energy consumption, improve the product quality, increase the production rate, and reduce the number of product rejects. It is well-known that shear horizontal surface acoustic wave (SH-SAW) propagation is sensitive to mass changes as well as to the mechanical properties of attached materials. In this work, the SH-SAW was used to monitor polymer property changes primarily dictated by variations in the viscoelasticity. The viscoelastic properties of a negative photoresist film were monitored throughout the ultraviolet (UV) light-induced polymer cross-linking process using SH-SAW delay line devices. Changes in the polymer film mass and viscoelasticity caused by UV exposure produced variations in the phase velocity and attenuation of the SH-SAW propagating in the structure. Based on measured polymer-coated delay line scattering transmission responses (S(21)) and the measured polymer layer thickness and density, the viscoelastic constants c(44) and eta(44) were extracted. The polymer thickness was found to decrease 0.6% during UV curing, while variations in the polymer density were determined to be insignificant. Changes of 6% in c(44) and 22% in eta(44) during the cross-linking process were observed, showing the sensitivity of the SH-SAW phase velocity and attenuation to changes in the polymer film viscoelasticity. These results indicate the potential for SH-SAW devices as online monitoring sensors for polymer film processing.

  7. Anomalous sound propagation due to the horizontal variation of seabed acoustic properties

    Institute of Scientific and Technical Information of China (English)

    LI Zhenglin; ZHANG Renhe; PENG Zhaohui; LI Xilu

    2004-01-01

    The sound propagation in shallow water is greatly influenced by the acoustic properties of seabed. An anomalous transmission loss was observed in an experiment, and a range dependent bottom model with horizontal variation of seabed acoustic property is proposed and could be well used to explain the anomalous phenomena. It is shown that the horizontal variation of bottom properties has a great effect on underwater sound propagation, and it should be given much attention in sound propagation and geoacoustic inversion problems.

  8. The experimental study of in situ acoustic properties in marine sediments

    Science.gov (United States)

    Fu, Shungsheng

    1998-10-01

    Since 1991, mainly supported by the US Navy, we have conducted a long term study of acoustic properties in marine sediments, including instrumentation development and a series of comprehensive experimental studies in natural environments. Our research work emphasizes in situ acoustic properties at sonic frequency, which the US Navy supports for better sonar interpretation. This dissertation is a summary of the work our group has done in recent years. The acoustic lance is a new instrument developed to measure in situ acoustic properties of the uppermost several meters of the seafloor. By using the acoustic lance, we are able to study the acoustic properties of marine sediments in a variety of natural environments. This dissertation combines five papers which have been either published, submitted or will be submitted to journals. In this dissertation, I describe the configuration and working principle of the lance, a technique of signal processing based on geophysical inverse theory for the lance signals, and three experimental studies conducted in three natural environments-sediment ponds on Mid-Atlantic Ridge (deep sea pelagic ooze), Kiel Bay gassy deposit (gassy silty clay), and Oahu Island off shore sand deposit (shallow water carbonate sands). The three experimental studies not only add new in situ data to the catalog of acoustic properties of marine sediments, but also provide new insight into acoustic behavior of marine sediments in natural environments. One of the important advantages of the lance is to obtain in situ acoustic data that address depth dependence of acoustic properties in the uppermost seabed. For the sediment ponds of Mid-Atlantic Ridge, we reported the velocity profiles in the uppermost 5 m of the seafloor which suggest that there is an acoustic channel lying just below the seafloor. Sound energy remains within the channel in propagation. The lance data provide in situ velocities and acoustic signal characteristics in gas- bearing sediments

  9. A mixed method for measuring low-frequency acoustic properties of macromolecular materials

    Institute of Scientific and Technical Information of China (English)

    LIU; Hongwei; YAO; Lei; ZHAO; Hong; ZHANG; Jichuan; XUE; Zhaohong

    2006-01-01

    A mixed method for measuring low-frequency acoustic properties of macromolecular materials is presented.The dynamic mechanical parameters of materials are first measured by using Dynamic Mechanical Thermal Apparatus(DMTA) at low frequencies,usually less than 100 Hz; then based on the Principles of Time-Temperature Super position (TTS),these parameters are extended to the frequency range that acousticians are concerned about,usually from hundreds to thousands of hertz; finally the extended dynamic mechanical parameters are transformed into acoustic parameters with the help of acoustic measurement and inverse analysis.To test the feasibility and accuracy,we measure a kind of rubber sample in DMTA and acquire the basic acoustic parameters of the sample by using this method.While applying the basic parameters to calculating characteristics of the sample in acoustic pipe,a reasonable agreement of sound absorption coefficients is obtained between the calculations and measurements in the acoustic pipe.

  10. Acoustic and Durational Properties of Indian English Vowels

    Science.gov (United States)

    Maxwell, Olga; Fletcher, Janet

    2009-01-01

    This paper presents findings of an acoustic phonetic analysis of vowels produced by speakers of English as a second language from northern India. The monophthongal vowel productions of a group of male speakers of Hindi and male speakers of Punjabi were recorded, and acoustic phonetic analyses of vowel formant frequencies and vowel duration were…

  11. Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies

    Science.gov (United States)

    Hettich, Mike; Jacob, Karl; Ristow, Oliver; Schubert, Martin; Bruchhausen, Axel; Gusev, Vitalyi; Dekorsy, Thomas

    2016-01-01

    We investigate the viscoelastic properties of confined molecular nano-layers by time resolved optical pump-probe measurements. Access to the elastic properties is provided by the damping time of acoustic eigenmodes of thin metal films deposited on the molecular nano-layers which show a strong dependence on the molecular layer thickness and on the acoustic eigen-mode frequencies. An analytical model including the viscoelastic properties of the molecular layer allows us to obtain the longitudinal sound velocity as well as the acoustic absorption coefficient of the layer. Our experiments and theoretical analysis indicate for the first time that the molecular nano-layers are much more viscous than elastic in the investigated frequency range from 50 to 120 GHz and thus show pronounced acoustic absorption. The longitudinal acoustic wavenumber has nearly equal real and imaginary parts, both increasing proportional to the square root of the frequency. Thus, both acoustic velocity and acoustic absorption are proportional to the square root of frequency and the propagation of compressional/dilatational acoustic waves in the investigated nano-layers is of the diffusional type, similar to the propagation of shear waves in viscous liquids and thermal waves in solids. PMID:27633351

  12. Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies

    Science.gov (United States)

    Hettich, Mike; Jacob, Karl; Ristow, Oliver; Schubert, Martin; Bruchhausen, Axel; Gusev, Vitalyi; Dekorsy, Thomas

    2016-09-01

    We investigate the viscoelastic properties of confined molecular nano-layers by time resolved optical pump-probe measurements. Access to the elastic properties is provided by the damping time of acoustic eigenmodes of thin metal films deposited on the molecular nano-layers which show a strong dependence on the molecular layer thickness and on the acoustic eigen-mode frequencies. An analytical model including the viscoelastic properties of the molecular layer allows us to obtain the longitudinal sound velocity as well as the acoustic absorption coefficient of the layer. Our experiments and theoretical analysis indicate for the first time that the molecular nano-layers are much more viscous than elastic in the investigated frequency range from 50 to 120 GHz and thus show pronounced acoustic absorption. The longitudinal acoustic wavenumber has nearly equal real and imaginary parts, both increasing proportional to the square root of the frequency. Thus, both acoustic velocity and acoustic absorption are proportional to the square root of frequency and the propagation of compressional/dilatational acoustic waves in the investigated nano-layers is of the diffusional type, similar to the propagation of shear waves in viscous liquids and thermal waves in solids.

  13. Parametrization of acoustic boundary absorption and dispersion properties in time-domain source/receiver reflection measurement

    NARCIS (Netherlands)

    De Hoop, A.T.; Lam, C.H.; Kooij, B.J.

    2005-01-01

    Closed-form analytic time-domain expressions are obtained for the acoustic pressure associated with the reflection of a monopole point-source excited impulsive acoustic wave by a planar boundary with absorptive and dispersive properties. The acoustic properties of the boundary are modeled as a local

  14. Parametrization of acoustic boundary absorption and dispersion properties in time-domain source/receiver reflection measurement

    NARCIS (Netherlands)

    De Hoop, A.T.; Lam, C.H.; Kooij, B.J.

    2005-01-01

    Closed-form analytic time-domain expressions are obtained for the acoustic pressure associated with the reflection of a monopole point-source excited impulsive acoustic wave by a planar boundary with absorptive and dispersive properties. The acoustic properties of the boundary are modeled as a local

  15. 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.

  16. Acoustic properties of Indian Ocean manganese nodules in relation to physical constitution and chemical composition

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.; Ramana, Y.V.

    , 1984; MA et al., 1986). This paper attempts to study the acoustical properties of nodules from different sediment environments in the Indian Ocean, because the physical constitution of nodules provides information on it's crystallochemical structure..., respectively. The above measurements were carried out following pulse transmit time method (SUBBARAJU and RAMANA, 1986) and verified by the compen- sated ultrasonic timer technique (RAMAt~A and SHARMA, 1984). Physical and acoustic properties were determined...

  17. Effects of construction changes in the teeth of a gear transmission on acoustic properties.

    Science.gov (United States)

    Wieczorek, Andrzej

    2012-01-01

    This paper presents results of experimental research on the acoustic properties of gear wheels with high-profile teeth with differentiated tooth height. Those results showed that gear transmissions with high-profile teeth have the best acoustic properties, with the value of the transverse contact ratio εα ≈ 2.0. They also showed that a reduction in tooth height, and thereby in contact ratio, increased the sound pressure level.

  18. Linkage between acoustic parameters and seabed sediment properties in the south-western Baltic Sea

    Science.gov (United States)

    Endler, Michael; Endler, Rudolf; Bobertz, Bernd; Leipe, Thomas; Arz, Helge W.

    2015-04-01

    Acoustic profiling methods are widely used to provide a rapid view into geological structures. For the interpretation of acoustic profiling results (single- and multi-beam), reliable geo-acoustic models are needed. Suitable geo-acoustic models covering a wide range of sediment types do not exist to date for the Baltic Sea. Based on surface sediment datasets, geo-acoustic models have been set up for the prediction of acoustical parameters derived from sedimentological data for south-western Baltic Sea surface sediments. Empirical relationships were created to predict key in situ parameters (p-wave velocity, wet bulk density) from sedimentological core data, notably grain density and water content. The Gassmann-Hamilton equations were used to set up a more generic physically based model. For the first time semi-empirical equations for the calculation of the elastic frame modulus and the solid sediment particle modulus were established by an iterative Gassmann-Hamilton fitting procedure. The resulting models have a remarkably good performance with, for example, a calculated sound velocity accuracy of about 17-32 m s-1 depending on model input data. The acoustic impedance of seafloor sediments can be estimated from single-beam echosounding if the contribution of seafloor reflectivity is extracted from the total acoustic signal. The data reveal a strong linkage between acoustic impedance and selected sediment properties (e.g. grain size, water content). This underlines the potential for effective mapping of seafloor sediment properties (e.g. habitat mapping). Furthermore, these geo-acoustic models can be used by marine geologists for a precise linkage between sediment facies identified in longer cores and corresponding acoustic facies recorded by high-resolution seismic profiling in future work.

  19. On the acoustic properties of vaporized submicron perfluorocarbon droplets.

    Science.gov (United States)

    Reznik, Nikita; Lajoinie, Guillaume; Shpak, Oleksandr; Gelderblom, Erik C; Williams, Ross; de Jong, Nico; Versluis, Michel; Burns, Peter N

    2014-06-01

    The acoustic characteristics of microbubbles created from vaporized submicron perfluorocarbon droplets with fluorosurfactant coating are examined. Utilizing ultra-high-speed optical imaging, the acoustic response of individual microbubbles to low-intensity diagnostic ultrasound was observed on clinically relevant time scales of hundreds of milliseconds after vaporization. It was found that the vaporized droplets oscillate non-linearly and exhibit a resonant bubble size shift and increased damping relative to uncoated gas bubbles due to the presence of coating material. Unlike the commercially available lipid-coated ultrasound contrast agents, which may exhibit compression-only behavior, vaporized droplets may exhibit expansion-dominated oscillations. It was further observed that the non-linearity of the acoustic response of the bubbles was comparable to that of SonoVue microbubbles. These results suggest that vaporized submicron perfluorocarbon droplets possess the acoustic characteristics necessary for their potential use as ultrasound contrast agents in clinical practice.

  20. Acoustic properties of a porous glass (vycor) at hypersonic frequencies.

    Science.gov (United States)

    Levelut, C; Pelous, J

    2007-10-17

    Brillouin scattering experiments have been performed from 5 to 1600 K in vycor, a porous silica glass. The acoustic velocity and attenuation at hypersonic frequencies are compared to those of bulk silica and others porous silica samples. The experimental evidence for the influence of porosity on the scattering by acoustic waves is compared to calculations. The correlation between internal friction and thermal conductivity at low temperature is discussed.

  1. Beam Forming Property of Coded Acoustic Signal for Long-Range Acoustic Navigation of a Cruising Autonomous Underwater Vehicle

    Science.gov (United States)

    Yoshitaka Watanabe,; Hiroshi Ochi,; Takuya Shimura,; Takehito Hattori,

    2010-07-01

    The property of beam forming by a receiver array placed on the side surface of an autonomous underwater vehicle (AUV) is considered in this paper. The aim of this study is to develop a long-range acoustic navigation system for a cruising AUV on the basis of the estimation of the horizontal direction of arrival (DOA) of an acoustic signal from reference source. The acoustic signal is coded using a maximum length sequence code. The influence of multipath waves to the estimation of horizontal DOA was particularly studied. When there are several multipath waves from various vertical DOAs, even if the horizontal DOAs of all the waves are the same, the multipath waves are influential to the estimation of the horizontal DOA. Then, the coded signal is useful to avoid the influence of the multipath waves. An exploratory experiment on the propagation of the acoustic signal for distance of about 16.6 km was performed in Suruga Bay. By simulating the condition similar to the experiment, it was indicated that the accuracy of the estimation of the horizontal DOA is within zero point several degrees in the experiment.

  2. Acoustical properties of dry and saturated porous media

    Science.gov (United States)

    Adler, P. M.; Malinouskaya, I.; Mourzenko, V. V.; Thovert, J. F.

    2009-04-01

    Our objective is to determine the macroscopic acoustical properties of porous media (either dry or saturated by an interstitial fluid) and to relate them to the mechanical and hydromechanical characteristics of the medium and its components. Wave propagation in a dry elastic material is governed by the elastodynamic equation. For a dry medium, the stress is zero on the pore surface. The medium is supposed to be spatially periodic and composed of identical cells. When the wave length lambda is very large when compared to the scale l of the heterogeneities, the medium behaves in a first approximation as an equivalent homogeneous material. All the fields can expanded as series of the small parameter eta= l/2 pi lambda, in terms of two space variables associated to the scales lambda et l, respectively. This expansion is introduced into the elastodynamic equation with appropriate boundary conditions. A series of non homogeneous partial differential equations are found for the successive orders in eta. The predominant order corresponds to the equivalent homogeneous material. The first order equation provides the polarization correction, the second one the celerity dispersion and the third one the attenuation. These equations are discretized by a finite volume formulation in a tetrahedral mesh which is either structured or not. The resulting linear system is solved by a conjugate gradient method. Each elementary volume may have specific properties. Wave propagation in a saturated medium is more complex since it is influenced by the solid and liquid phases. When a periodic oscillation is imposed, the solid displacements are governed by the elastodynamic and the Stokes equations coupled by boundary conditions at the interface. The solutions to these equations yield the macroscopic characteristics of the medium. The first equation yields two independent problems in the solid, one identical to dry media and one corresponding to a medium submitted to an interstitial

  3. Reproducibility experiments on measuring acoustical properties of rigid-frame porous media (round-robin tests).

    Science.gov (United States)

    Horoshenkov, Kirill V; Khan, Amir; Bécot, François-Xavier; Jaouen, Luc; Sgard, Franck; Renault, Amélie; Amirouche, Nesrine; Pompoli, Francesco; Prodi, Nicola; Bonfiglio, Paolo; Pispola, Giulio; Asdrubali, Francesco; Hübelt, Jörn; Atalla, Noureddine; Amédin, Celse K; Lauriks, Walter; Boeckx, Laurens

    2007-07-01

    This paper reports the results of reproducibility experiments on the interlaboratory characterization of the acoustical properties of three types of consolidated porous media: granulated porous rubber, reticulated foam, and fiberglass. The measurements are conducted in several independent laboratories in Europe and North America. The studied acoustical characteristics are the surface complex acoustic impedance at normal incidence and plane wave absorption coefficient which are determined using the standard impedance tube method. The paper provides detailed procedures related to sample preparation and installation and it discusses the dispersion in the acoustical material property observed between individual material samples and laboratories. The importance of the boundary conditions, homogeneity of the porous material structure, and stability of the adopted signal processing method are highlighted.

  4. ACOUSTIC PROPERTIES IN ARIZONA CYPRESS LOGS: A TOOL TO SELECT WOOD FOR SOUNDING BOARD

    Directory of Open Access Journals (Sweden)

    Ajang Tajdini

    2011-02-01

    Full Text Available In this study, variation in acoustic properties of Arizona cypress wood was monitored from pith to bark as affected by tapering of the growth ring width. Specific modulus of elasticity, acoustic coefficient, damping, and acoustic conversion efficiency were calculated. It was shown that the outer parts of the stem, close to the bark containing narrower growth rings, exhibited lower damping due to internal friction and higher sound radiation. Our finding theoretically justified the luthier craftsmen’s traditional preference toward timbers with narrow growth rings to make sounding boards in musical instruments.

  5. Density-dependent acoustic properties of PBX 9502

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Geoffrey W [Los Alamos National Laboratory; Thompson, Darla G [Los Alamos National Laboratory; Deluca, Racci [Los Alamos National Laboratory; Hartline, Ernest L [Los Alamos National Laboratory; Hagelberg, Stephanie I [Los Alamos National Laboratory

    2009-07-31

    We have measured the longitudinal and shear acoustic velocities of PBX 9502 as a function of density for die-pressed samples over the range 1.795 g/cc to 1.888 g/cc. The density dependence of the velocities is linear. Thermal cycling of PBX 9502 is known to induce irreversible volume growth. We have measured this volume growth dependence on density for a subset of the pressed parts and find that the most growth occurs for the samples with lowest initial density. The acoustic velocity changes due to the volume growth are significant and reflect damage in the samples.

  6. The Effects of Sediment Properties on Low Frequency Acoustic Propagation

    Science.gov (United States)

    2013-09-30

    Experimental observations and seismo-acoustic inversions,” J. Acoust. Soc. Am. 110 (4), 1908-1916, 2001. 4. D. Rauch, “ Seismic interface waves in coastal...Predicting underwater radiated noise levels due to the first offshore wind turbine installation in the U.S.,” POMA 19, 040067 (2013). 21. Edward...offshore wind turbine noise using finite element and parabolic equation models”. This paper was co- authored by Gopu R. Potty, James H. Miller, Kevin B. Smith, and Georges Dossot.

  7. The Influence of the Shallow Water Internal Tide on the Properties of Acoustic Signals

    Science.gov (United States)

    2016-06-07

    LONG-TERM GOAL Quantitatively relate the temporal and spatial properties of shallow water acoustic signals to the physical processes that cause the... quantitative measure of the tidally controlled water column variability on acoustic systems the response of a Bartlett matched field processor (vertical array...moved from shallow water (~ 35 m) to deeper water (~ 60 m). Shipboard ADCP data indicated the flow conditions to be caused by an ebb barotropic tide

  8. Piezoelectric, Mechanical and Acoustic Properties of KNaNbOF5 from First-Principles Calculations

    Directory of Open Access Journals (Sweden)

    Han Han

    2015-12-01

    Full Text Available Recently, a noncentrosymmetric crystal, KNaNbOF5, has attracted attention due to its potential to present piezoelectric properties. Although α- and β-KNaNbOF5 are similar in their stoichiometries, their structural frameworks, and their synthetic routes, the two phases exhibit very different properties. This paper presents, from first-principles calculations, comparative studies of the structural, electronic, piezoelectric, and elastic properties of the α and the β phase of the material. Based on the Christoffel equation, the slowness surface of the acoustic waves is obtained to describe its acoustic prosperities. These results may benefit further applications of KNaNbOF5.

  9. Effects of the acoustic properties of infant-directed speech on infant word recognition.

    Science.gov (United States)

    Song, Jae Yung; Demuth, Katherine; Morgan, James

    2010-07-01

    A number of studies have examined the acoustic differences between infant-directed speech (IDS) and adult-directed speech, suggesting that the exaggerated acoustic properties of IDS might facilitate infants' language development. However, there has been little empirical investigation of the acoustic properties that infants use for word learning. The goal of this study was thus to examine how 19-month-olds' word recognition is affected by three acoustic properties of IDS: slow speaking rate, vowel hyper-articulation, and wide pitch range. Using the intermodal preferential looking procedure, infants were exposed to half of the test stimuli (e.g., Where's the book?) in typical IDS style. The other half of the stimuli were digitally altered to remove one of the three properties under investigation. After the target word (e.g., book) was spoken, infants' gaze toward target and distractor referents was measured frame by frame to examine the time course of word recognition. The results showed that slow speaking rate and vowel hyper-articulation significantly improved infants' ability to recognize words, whereas wide pitch range did not. These findings suggest that 19-month-olds' word recognition may be affected only by the linguistically relevant acoustic properties in IDS.

  10. Acoustical properties of individual liposome-loaded microbubbles.

    Science.gov (United States)

    Luan, Ying; Faez, Telli; Gelderblom, Erik; Skachkov, Ilya; Geers, Bart; Lentacker, Ine; van der Steen, Ton; Versluis, Michel; de Jong, Nico

    2012-12-01

    A comparison between phospholipid-coated microbubbles with and without liposomes attached to the microbubble surface was performed using the ultra-high-speed imaging camera (Brandaris 128). We investigated 73 liposome-loaded microbubbles (loaded microbubbles) and 41 microbubbles without liposome loading (unloaded microbubbles) with a diameter ranging from 3-10 μm at frequencies ranging from 0.6-3.8 MHz and acoustic pressures ranging from 5-100 kPa. The experimental data showed nearly the same shell elasticity for the loaded and unloaded bubbles, but the shell viscosity was higher for loaded bubbles compared with unloaded bubbles. For loaded bubbles, a higher pressure threshold for the bubble vibrations was noticed. In addition, an "expansion-only" behavior was observed for up to 69% of the investigated loaded bubbles, which mostly occurred at low acoustic pressures (≤30 kPa). Finally, fluorescence imaging showed heterogeneity of liposome distributions of the loaded bubbles.

  11. Acoustic Properties of Return Strokes and M-components From Rocket-Triggered Lightning

    Science.gov (United States)

    Dayeh, M. A.; Fuselier, S. A.; Dwyer, J. R.; Uman, M. A.; Jordan, D.; Carvalho, F. L.; Rassoul, H.

    2015-12-01

    Using a linear, one-dimensional array of 15 microphones situated 95 meters from the lightning channel; we measure the acoustic signatures from 11 triggered-lightning events comprising 41 return strokes and 28 M-components. Measurements were taken at the International Center for Lightning Research and Testing (ICLRT) in Camp Blanding, FL during the summer of 2014. Recently, we reported that beamforming signal processing enables acoustic imaging of the lightning channel at high frequencies (Dayeh et al. 2015). Following up on the work, we report on the characteristics of the acoustic measurements in terms of sound pressure amplitude, peak currents, power spectral density (PSD) properties, and the inferred energy input. In addition, we find that M-component do not create acoustic signatures in most occasions; we discuss these cases in context of the associated current amplitude, rise time, and background continuing current.

  12. Acoustic Tonal and Vector Properties of Red Hind Grouper Vocalizations

    Science.gov (United States)

    Matthews, Cameron Anthony

    Vertebrates are the most prodigious vocalizing animals in existence, and the most diverse methods of acoustic communication among vertebrates can be found in the ocean. Relatively many teleost fish are gifted with the ability to communicate acoustically, and the family of serranidae often performs this as a function of the swim bladder. Epinephelus Guttatus (E. guttatus), or more commonly the red hind grouper, is equipped with a drum shaped swim bladder acting as a monopole under typical ocean conditions. This configuration allows for what is understood to be omnidirectional projection of tones approximately centered between 40 and 440 Hz and spanning anywhere from 40 to 200 Hz of bandwidth and modulation effects based on observed data provided by researchers. Prior studies on many other fish show correlation in acoustic communication profile with length, size and sexual identity. In the red hind, sexual dimorphism leads to an inherent female identity in all juvenile fish which converts to male according to environmental factors, recommending at least consistent organs across both sexes be assumed even if not in use. Much research has been performed on male fish vocalization in terms of spectral content. Communication in fish is a complex multi-modal process, with acoustic communication being important for many of the species, particularly those in the littoral regions of the worlds' oceans. If identifying characteristics of the red hind vocalization can be isolated based on detection, classification, tracking and localizing methodologies, then these identifying characteristics may indeed lead to passive feature identification that allows for estimation of individual fish mass. Hypotheses based on vector, cyclostationary and classical tonal mechanics are presented for consideration. A battery of test data collection events, applying pre-recorded fish vocalizations to a geolocated undersea sound source were conducted. The results are supplied with the intent of

  13. -Irradiation effect on the acoustical properties of zinc lead borate glasses

    Science.gov (United States)

    Sharma, G.; Singh, K.; Manupriya; Klare, H. S.; Rajendran, V.; Gayathri Devi, A. V.; Narang, S. B.

    2005-11-01

    The effect of -irradiation on the acoustical properties of xZnO.2xPbO.(1-3x)B2O3 glasses has been studied. Ultrasonic velocity and attenuation measurements have been made before and after -irradiation at room temperature in the frequency range 2.25-10 MHz. From the measured density and ultrasonic velocity data, the elastic moduli, Poisson's ratio and other parameters have been obtained. Changes in the acoustical properties are explained in terms of radiation-induced structural defects and the influence of PbO/ZnO in the glass network structure.

  14. Measurements and empirical model of the acoustic properties of reticulated vitreous carbon

    Science.gov (United States)

    Muehleisen, Ralph T.; Beamer, C. Walter; Tinianov, Brandon D.

    2005-02-01

    Reticulated vitreous carbon (RVC) is a highly porous, rigid, open cell carbon foam structure with a high melting point, good chemical inertness, and low bulk thermal conductivity. For the proper design of acoustic devices such as acoustic absorbers and thermoacoustic stacks and regenerators utilizing RVC, the acoustic properties of RVC must be known. From knowledge of the complex characteristic impedance and wave number most other acoustic properties can be computed. In this investigation, the four-microphone transfer matrix measurement method is used to measure the complex characteristic impedance and wave number for 60 to 300 pore-per-inch RVC foams with flow resistivities from 1759 to 10 782 Pa s m-2 in the frequency range of 330 Hz-2 kHz. The data are found to be poorly predicted by the fibrous material empirical model developed by Delany and Bazley, the open cell plastic foam empirical model developed by Qunli, or the Johnson-Allard microstructural model. A new empirical power law model is developed and is shown to provide good predictions of the acoustic properties over the frequency range of measurement. Uncertainty estimates for the constants of the model are also computed. .

  15. Acoustic and elastic properties of Sn{sub 2}P{sub 2}S{sub 6} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mys, O; Martynyuk-Lototska, I; Vlokh, R [Institute of Physical Optics of the Ministry of Education and Science of Ukraine, 23 Dragomanov Street, 79005 Lviv (Ukraine); Grabar, A [Istitute for Solid State Physics and Chemistry, Uzhgorod National University, 54 Voloshyn Street, 88000 Uzhgorod (Ukraine)], E-mail: vlokh@ifo.lviv.ua

    2009-07-01

    We present the results concerned with acoustic and elastic properties of Sn{sub 2}P{sub 2}S{sub 6} crystals. The complete matrices of elastic stiffness and compliance coefficients are determined in both the crystallographic coordinate system and the system associated with eigenvectors of the elastic stiffness tensor. The acoustic slowness surfaces are constructed and the propagation and polarization directions of the slowest acoustic waves promising for acousto-optic interactions are determined on this basis. The acoustic obliquity angle and the deviation of polarization of the acoustic waves from purely transverse or longitudinal states are quantitatively analysed.

  16. Acoustic properties in glycerol glass-former: Molecular dynamics simulation

    Science.gov (United States)

    Busselez, Remi; Pezeril, Thomas; Institut des Materiaux et Molecules du Mans Team

    2013-03-01

    Study of high-frequency collective dynamics around TeraHertz region in glass former has been a subject of intense investigations and debates over the past decade. In particular, the presence of the Boson peak characteristic of glassy material and its relation to other glass anomalies. Recently, experiments and simulations have underlined possible relation between Boson peak and transverse acoustic modes in glassy materials. In particular, simulations of simple Lennard Jones glass former have shown a relation between Ioffe-Regel criterion in transverse modes and Boson peak. We present here molecular dynamics simulation on high frequency dynamics of glycerol. In order to study mesoscopic order (0.5-5nm-1), we made use of large simulation box containing 80000 atoms. Analysis of collective longitudinal and transverse acoustic modes shows striking similarities in comparison with simulation of Lennard-Jones particles. In particular, it seems that a connection may exist between Ioffe-Regel criterion for transverse modes and Bose Peak frequency. However,in our case we show that this connection may be related with structural correlation arising from molecular clusters.

  17. Acoustic properties of sintered FeCrAlY foams with open cells (Ⅱ): Sound attenuation

    Institute of Scientific and Technical Information of China (English)

    LU TianJian; M.KEPETS; A.P.DOWLING

    2008-01-01

    Open-celled metal foams fabricated through metal sintering offers novel mechani-cal, thermal and acoustic properties. Previously, polymer foams were used as a means of absorbing acoustic energy. However, the structural applications of these foams are inherently limited. The metal sintering approach provides a cost-effective means for the mass-production of open-cell foams from a range of materials, in-cluding high-temperature steel alloys. The low Reynolds number fluid properties of sintered steel alloy (FeCrAIY) foams were investigated in a previous study. The static flow resistance of the foams was modeled based on s cylinder and s sphere arranged in a periodic lattice at general incidence to the flow, with the resulting predictions correlating well to measurements. The application of the flow resis-tance in an acoustic model is the primary focus of the present study. The predic-tions for the static flow resistance of the sintered foams are first used in a theo-retical model to determine the characteristic impedances, as well as the propaga-tion constants of the foams. Subsequently, the predicted acoustic performance of the foams is compared to experimental results. Finally, the design space for a simple acoustic absorber incorporating sintered foams is examined, with the ef-fects of absorber size, foam selection, and foam spacing explored.

  18. Acoustic properties of sintered FeCrAlY foams with open cells (Ⅱ): Sound attenuation

    Institute of Scientific and Technical Information of China (English)

    M.; KEPETS; A.; P.; DOWLING2

    2008-01-01

    Open-celled metal foams fabricated through metal sintering offers novel mechani- cal, thermal and acoustic properties. Previously, polymer foams were used as a means of absorbing acoustic energy. However, the structural applications of these foams are inherently limited. The metal sintering approach provides a cost-effective means for the mass-production of open-cell foams from a range of materials, in- cluding high-temperature steel alloys. The low Reynolds number fluid properties of sintered steel alloy (FeCrAlY) foams were investigated in a previous study. The static flow resistance of the foams was modeled based on a cylinder and a sphere arranged in a periodic lattice at general incidence to the flow, with the resulting predictions correlating well to measurements. The application of the flow resis- tance in an acoustic model is the primary focus of the present study. The predic- tions for the static flow resistance of the sintered foams are first used in a theo- retical model to determine the characteristic impedances, as well as the propaga- tion constants of the foams. Subsequently, the predicted acoustic performance of the foams is compared to experimental results. Finally, the design space for a simple acoustic absorber incorporating sintered foams is examined, with the ef- fects of absorber size, foam selection, and foam spacing explored.

  19. Characterizing the acoustic properties of the Jet Lab at the National Center for Physical Acoustics

    Science.gov (United States)

    Lieblong, Joshua Anderson

    Aerodynamic noise has been a problem since the first use of the jet engine for military aircraft in World War II. For further uses of the jet engine to be possible, problems due to jet noise must be researched and addressed. Anechoic chambers were proposed as a testing facility for research in aerodynamic noise because of their supposed free-field characteristics. The international standard ISO 3745-1977 was introduced to determine whether the facilities could be considered anechoic, semi-anechoic, or neither. An experiment was designed to determine at what frequencies the National Center for Physical Acoustics' Jet Lab Facility is non-anechoic, semi-anechoic, or anechoic. To comply with the guidelines of ISO 3745- 1977, three sources were designed and tested at frequencies from 25 Hz to 16000 Hz. The voltages were acquired at each frequency to calculate the sound pressure level and determine if the calculated values are within the allowed tolerance of the inverse square law.

  20. The Acoustic Properties of Vowels: A Tool for Improving Articulation and Comprehension of English

    Science.gov (United States)

    McCombs, Candalene J.

    2006-01-01

    Correct pronunciation is often a later step in the process of teaching English as a second language. However, a focus on the correct articulation of vowels can significantly improve listening and comprehension skills as well as articulatory skills. Vowels and consonants differ in their acoustic properties. Unlike consonants, vowel sounds are…

  1. An improved instrumental characterization of mechanical and acoustic properties of crispy cellular solid food

    NARCIS (Netherlands)

    Vliet, T. van; Castro-Prada, E.M.; Luyten, H.; Lichtendonk, W.; Hamer, R.J.

    2007-01-01

    A detailed study was performed to simultaneously measure the mechanical and acoustic properties of crispy cellular solid foods. Different critical aspects are discussed in order to assess optimal test conditions. These are primarily data sampling rate, microphone positioning, frequency spectrum of i

  2. High-pressure acoustic properties of glycerol studied by Brillouin spectroscopy

    Science.gov (United States)

    Jeong, Min-Seok; Ko, Jae-Hyeon; Ko, Young Ho; Kim, Kwang Joo

    2015-12-01

    Acoustic properties of glycerol was investigated in a wide pressure range from ambient pressure to 30.9 GPa by using a multi-pass Fabry-Perot interferometer and a diamond anvil cell. Pressure dependences of the sound velocity and the Brillouin linewidth showed substantial changes at low pressures below ~4 GPa. This was attributed to the coupling between the main structural relaxation process and the longitudinal acoustic waves. The pressure dependence of the refractive index and the density of glycerol could be obtained by using two scattering geometries and the Lorentz-Lorenz relation.

  3. High-pressure acoustic properties of glycerol studied by Brillouin spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Min-Seok [Department of Physics, Hallym University, Chuncheon, Gangwondo 200-702 (Korea, Republic of); Ko, Jae-Hyeon, E-mail: hwangko@hallym.ac.kr [Department of Physics, Hallym University, Chuncheon, Gangwondo 200-702 (Korea, Republic of); Ko, Young Ho; Kim, Kwang Joo [Agency for Defense Development, 4-2-2, P.O. Box 35, Yuseong, Daejeon 305-600 (Korea, Republic of)

    2015-12-01

    Acoustic properties of glycerol was investigated in a wide pressure range from ambient pressure to 30.9 GPa by using a multi-pass Fabry–Perot interferometer and a diamond anvil cell. Pressure dependences of the sound velocity and the Brillouin linewidth showed substantial changes at low pressures below ~4 GPa. This was attributed to the coupling between the main structural relaxation process and the longitudinal acoustic waves. The pressure dependence of the refractive index and the density of glycerol could be obtained by using two scattering geometries and the Lorentz–Lorenz relation.

  4. Curvature properties of the slowness surface of the system of crystal acoustics for cubic crystals

    OpenAIRE

    LIESS, Otto

    2008-01-01

    In this paper we study geometric properties of the slowness surface of the system of crystal acoustics for cubic crystals. In particular we shall study curvature properties of the surface and the behaviour of the surface near singular points. The main result is that in the generic nearly isotropic case there are no planes which are tangent to the surface along entire curves. This is in contrast with what happens for the slowness surface of the system of crystal optics for...

  5. Acoustic property reconstruction of a pygmy sperm whale (Kogia breviceps) forehead based on computed tomography imaging.

    Science.gov (United States)

    Song, Zhongchang; Xu, Xiao; Dong, Jianchen; Xing, Luru; Zhang, Meng; Liu, Xuecheng; Zhang, Yu; Li, Songhai; Berggren, Per

    2015-11-01

    Computed tomography (CT) imaging and sound experimental measurements were used to reconstruct the acoustic properties (density, velocity, and impedance) of the forehead tissues of a deceased pygmy sperm whale (Kogia breviceps). The forehead was segmented along the body axis and sectioned into cross section slices, which were further cut into sample pieces for measurements. Hounsfield units (HUs) of the corresponding measured pieces were obtained from CT scans, and regression analyses were conducted to investigate the linear relationships between the tissues' HUs and velocity, and HUs and density. The distributions of the acoustic properties of the head at axial, coronal, and sagittal cross sections were reconstructed, revealing that the nasal passage system was asymmetric and the cornucopia-shaped spermaceti organ was in the right nasal passage, surrounded by tissues and airsacs. A distinct dense theca was discovered in the posterior-dorsal area of the melon, which was characterized by low velocity in the inner core and high velocity in the outer region. Statistical analyses revealed significant differences in density, velocity, and acoustic impedance between all four structures, melon, spermaceti organ, muscle, and connective tissue (p acoustic properties of the forehead tissues provide important information for understanding the species' bioacoustic characteristics.

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

    Energy Technology Data Exchange (ETDEWEB)

    Thurman E. Scott, Jr.; Younane Abousleiman

    2004-04-01

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

  7. 3D Acoustic Modelling of Dissipative Silencers with Nonhomogeneous Properties and Mean Flow

    Directory of Open Access Journals (Sweden)

    E. M. Sánchez-Orgaz

    2014-07-01

    Full Text Available A finite element approach is proposed for the acoustic analysis of automotive silencers including a perforated duct with uniform axial mean flow and an outer chamber with heterogeneous absorbent material. This material can be characterized by means of its equivalent acoustic properties, considered coordinate-dependent via the introduction of a heterogeneous bulk density, and the corresponding material airflow resistivity variations. An approach has been implemented to solve the pressure wave equation for a nonmoving heterogeneous medium, associated with the problem of sound propagation in the outer chamber. On the other hand, the governing equation in the central duct has been solved in terms of the acoustic velocity potential considering the presence of a moving medium. The coupling between both regions and the corresponding acoustic fields has been carried out by means of a perforated duct and its acoustic impedance, adapted here to include absorbent material heterogeneities and mean flow effects simultaneously. It has been found that bulk density heterogeneities have a considerable influence on the silencer transmission loss.

  8. 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.

  9. ?Underwater acoustic channel properties ?in the Gulf of Naples and their effects ?on digital data transmission

    Directory of Open Access Journals (Sweden)

    G. Iannaccone

    2007-06-01

    Full Text Available ?In this paper we studied the physical properties of the Gulf of Naples (Southern Italy for its use as a commu- nication channel for the acoustic transmission of digital data acquired by seismic instruments on the seafloor to a moored buoy. The acoustic link will be assured by high frequency acoustic modems operating with a central frequency of 100 kHz and a band pass of 10 kHz. The main operational requirements of data transmission con- cern the near horizontal acoustic link, the maximum depth of the sea being about 300 m and the planned hori- zontal distance between seismic instruments and buoy 2 km. This study constructs the signal-to-noise ratio maps to understand the limits beyond which the clarity of the transmission is no longer considered reliable. Using ray- theory, we compute the amplitudes of a transmitted signal at a grid of 21×12 receivers to calculate the transmis- sion loss at each receiver. The signal-to-noise ratio is finally computed for each receiver knowing also the trans- mitter source level and the acoustic noise level in the Gulf of Naples. The results show that the multipath effects predominate over the effects produced by the sound velocity gradient in the sea in the summer period. In the case of omnidirectional transmitters with a Source Level (SL of 165 dB and a baud rate of 2.4 kbit/s, the results al- so show that distances of 1400-1600 m can be reached throughout the year for transmitter-receiver connections below 50 m depth in the underwater acoustic channel.

  10. {gamma}-irradiation effect on the acoustical properties of zinc lead borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, G.; Singh, K.; Manupriya; Klare, H.S. [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Rajendran, V.; Gayathri Devi, A.V. [Department of Physics, Mepco Schlenk Engineering College, Mepco Engineering College (P.O.) 626005, Virudhunagar, Tamil Nadu (India); Narang, S.B. [Department of Electronics and Technology, Guru Nanak Dev University, Amritsar 143005 (India)

    2005-11-01

    The effect of {gamma}-irradiation on the acoustical properties of xZnO.2xPbO.(1-3x)B{sub 2}O{sub 3} glasses has been studied. Ultrasonic velocity and attenuation measurements have been made before and after {gamma}-irradiation at room temperature in the frequency range 2.25-10 MHz. From the measured density and ultrasonic velocity data, the elastic moduli, Poisson's ratio and other parameters have been obtained. Changes in the acoustical properties are explained in terms of radiation-induced structural defects and the influence of PbO/ZnO in the glass network structure. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Sensitivity of simulated transcranial ultrasound fields to acoustic medium property maps

    Science.gov (United States)

    Robertson, James; Martin, Eleanor; Cox, Ben; Treeby, Bradley E.

    2017-04-01

    High intensity transcranial focused ultrasound is an FDA approved treatment for essential tremor, while low-intensity applications such as neurostimulation and opening the blood brain barrier are under active research. Simulations of transcranial ultrasound propagation are used both for focusing through the skull, and predicting intracranial fields. Maps of the skull acoustic properties are necessary for accurate simulations, and can be derived from medical images using a variety of methods. The skull maps range from segmented, homogeneous models, to fully heterogeneous models derived from medical image intensity. In the present work, the impact of uncertainties in the skull properties is examined using a model of transcranial propagation from a single element focused transducer. The impact of changes in bone layer geometry and the sound speed, density, and acoustic absorption values is quantified through a numerical sensitivity analysis. Sound speed is shown to be the most influential acoustic property, and must be defined with less than 4% error to obtain acceptable accuracy in simulated focus pressure, position, and volume. Changes in the skull thickness of as little as 0.1 mm can cause an error in peak intracranial pressure of greater than 5%, while smoothing with a 1 \\text{m}{{\\text{m}}3} kernel to imitate the effect of obtaining skull maps from low resolution images causes an increase of over 50% in peak pressure. The numerical results are confirmed experimentally through comparison with sonications made through 3D printed and resin cast skull bone phantoms.

  12. Sensitivity of simulated transcranial ultrasound fields to acoustic medium property maps.

    Science.gov (United States)

    Robertson, James; Martin, Eleanor; Cox, Ben; Treeby, Bradley E

    2017-04-07

    High intensity transcranial focused ultrasound is an FDA approved treatment for essential tremor, while low-intensity applications such as neurostimulation and opening the blood brain barrier are under active research. Simulations of transcranial ultrasound propagation are used both for focusing through the skull, and predicting intracranial fields. Maps of the skull acoustic properties are necessary for accurate simulations, and can be derived from medical images using a variety of methods. The skull maps range from segmented, homogeneous models, to fully heterogeneous models derived from medical image intensity. In the present work, the impact of uncertainties in the skull properties is examined using a model of transcranial propagation from a single element focused transducer. The impact of changes in bone layer geometry and the sound speed, density, and acoustic absorption values is quantified through a numerical sensitivity analysis. Sound speed is shown to be the most influential acoustic property, and must be defined with less than 4% error to obtain acceptable accuracy in simulated focus pressure, position, and volume. Changes in the skull thickness of as little as 0.1 mm can cause an error in peak intracranial pressure of greater than 5%, while smoothing with a 1 [Formula: see text] kernel to imitate the effect of obtaining skull maps from low resolution images causes an increase of over 50% in peak pressure. The numerical results are confirmed experimentally through comparison with sonications made through 3D printed and resin cast skull bone phantoms.

  13. Acoustic properties of glacial ice for neutrino detection and the Enceladus Explorer

    CERN Document Server

    Helbing, K; Naumann, U; Eliseev, D; Heinen, D; Scholz, F; Wiebusch, C; Zierke, S

    2016-01-01

    Ultra high energy neutrinos may be observed in ice by the emission of acoustic signals. The SPATS detector has investigated the possibility of observing GZK-neutrinos in the clear ice near the South Pole at the IceCube detector site. To explore other potential detection sites glacial ice in the Alps and in Antarctica has been surveyed for its acoustical properties. The purpose of the Enceladus Explorer (EnEx), on the other hand, is the search for extraterrestrial life on the Saturn moon Enceladus. Here acoustics is used to maneuver a subsurface probe inside the ice by trilateration of signals. A system of acoustic transducers has been developed to study both applications. In the south polar region of the moon Enceladus there are secluded crevasses. These are filled with liquid water, probably heated by tidal forces due to the short distance to Saturn. We intend to take a sample of water from these crevasses by using a combination of a melt down and steering probe called IceMole (IM). Maneuvering IM requires a...

  14. Traveling wave tube measurements for low-frequency properties of underwater acoustic materials

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A traveling wave tube measurement technique for measuring acoustic properties of underwater acoustic materials was developed. Water temperature and pressure environments of the ocean can be simulated in a water-filled tube, and the acoustic parameters of samples of underwater acoustic materials are measured in the range of low-frequency. A tested sample is located at central position of the tube. A pair of projectors is separately located at both ends of the tube. Using an active anechoic technique, the sound wave transmitting the tested sample is hardly reflected by the surface of secondary transducer. So the traveling sound field is built up in the tube. By separately calculating the transfer functions of every pair of double hydrophones in the sound fields from the both sides of the sample, its reflection coefficients and transmission coefficients are obtained. In the measurement system, the inside diameter of the tube is Φ208 mm, the working frequency range is from 100 to 4000 Hz, the maximum pressure is 5 MPa. The reflection coefficients and transmission coefficients of a water layer and a stainless steel layer samples are measured actually and calculated theoretically. The results show that the measured values are in good agreement with the values calculated, and the measurement uncertainty is not greater than 1.5 dB.

  15. Inversion of High Frequency Acoustic Data for Sediment Properties Needed for the Detection and Classification of UXOs

    Science.gov (United States)

    2015-05-26

    inversion testing. Due to time limitations and to facilitate the deployments of both sonars, the 7125s were deployed using a pole mount on the...FINAL REPORT Inversion of High Frequency Acoustic Data for Sediment Properties Needed for the Detection and Classification of UXOs SERDP...2015 Inversion of High Frequency Acoustic Data for Sediment Properties Needed for the Detection and Classification of UXO’s W912HQ-12-C-0049 MR

  16. Correlations between the in situ acoustic properties and geotechnical parameters of sediments in the Yellow Sea, China

    Science.gov (United States)

    Liu, Baohua; Han, Tongcheng; Kan, Guangming; Li, Guanbao

    2013-11-01

    Knowledge about the marine sediment acoustic properties is a key to understanding wave propagation in sediments and is very important for military oceanography and ocean engineering. We developed a hydraulic-drived self-contained in situ sediment acoustic measurement system, and measured for the first time the in situ acoustic properties of sediments on 78 stations in the Yellow Sea, China, by employing this system. The relationships between the in situ measured acoustic properties and the onboard or laboratory determined geotechnical parameters were analyzed. Porosity was found to be the dominant factor in reducing velocity in a quadratic fashion; velocity showed an increment with bulk density and a decrement with mean grain size and clay content both with a nonlinear dependence; acoustic attenuation showed a bell-shaped correlation with porosity and mean grain size but reduced with clay content of the sediments. The attenuation results indicate that intergrain friction rather than viscous interactions between pore fluid and solid grains is the dominant loss mechanism in our marine sediments. The relationships established would be used to predict the geotechnical parameters from in situ measured acoustic properties and vice versa, as well as being an indicator of the seafloor processes, potential gas bubbles hazard and gas hydrates resources or other suitable targets of acoustic surveys.

  17. 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.

  18. Curvature properties of the slowness surface of the system of crystal acoustics for cubic crystals II

    OpenAIRE

    LIESS, Otto; Sonobe, Tetsuya

    2012-01-01

    In this paper we study geometric properties of the slowness surface of the system of crystal acoustics for cubic crystals in the special case when the stiffness constants satisfy the condition $a = -2b$. The paper is a natural continuation of the paper [9] in which related properties were studied for general constants $a$ and $b$, but assuming that we were in the nearly isotropic case, in which case $a - b$ has to be small. We also take this opportunity to correct a state...

  19. Acoustical properties of some modern partitioning glass walls systems – case study

    Directory of Open Access Journals (Sweden)

    Ioana-Mihaela ALEXE

    2014-04-01

    Full Text Available The case study presents the results of laboratory measurements carried out for the determination of airborne sound insulation properties for various modern partition glass walls systems. The analyzed partition glass walls were made with structures of aluminum profiles and with sheets of glazed materials. Laboratory measurements for determining the airborne sound insulation of walls were performed in the airborne sound insulation stand of Building Acoustics Laboratory of NRDI URBAN INCERC, INCERC Bucharest Branch, in accordance with EN ISO 10140- 2 "Acoustics. Laboratory measurement of sound insulation of building elements. Part 2: Measurement of airborne sound insulation". Measurement results are presented as airborne sound insulation indexes, Rw, and in graph form in the range of frequency 100 ... 3150 Hz. Rating of sound insulation of the walls was made in accordance with EN ISO 717-1 "Acoustics. Rating of sound insulation in buildings and of building elements. Part 1: Airborne sound insulation". After analyzing the results of the measurements, conclusions were drawn regarding the influence of partition glass walls structure on sound insulation properties, both on airborne sound insulation index, Rw, and on graphical results in the frequency range.

  20. Biologically relevant photoacoustic imaging phantoms with tunable optical and acoustic properties

    Science.gov (United States)

    Vogt, William C.; Jia, Congxian; Wear, Keith A.; Garra, Brian S.; Joshua Pfefer, T.

    2016-10-01

    Established medical imaging technologies such as magnetic resonance imaging and computed tomography rely on well-validated tissue-simulating phantoms for standardized testing of device image quality. The availability of high-quality phantoms for optical-acoustic diagnostics such as photoacoustic tomography (PAT) will facilitate standardization and clinical translation of these emerging approaches. Materials used in prior PAT phantoms do not provide a suitable combination of long-term stability and realistic acoustic and optical properties. Therefore, we have investigated the use of custom polyvinyl chloride plastisol (PVCP) formulations for imaging phantoms and identified a dual-plasticizer approach that provides biologically relevant ranges of relevant properties. Speed of sound and acoustic attenuation were determined over a frequency range of 4 to 9 MHz and optical absorption and scattering over a wavelength range of 400 to 1100 nm. We present characterization of several PVCP formulations, including one designed to mimic breast tissue. This material is used to construct a phantom comprised of an array of cylindrical, hemoglobin-filled inclusions for evaluation of penetration depth. Measurements with a custom near-infrared PAT imager provide quantitative and qualitative comparisons of phantom and tissue images. Results indicate that our PVCP material is uniquely suitable for PAT system image quality evaluation and may provide a practical tool for device validation and intercomparison.

  1. On the Relation between Electrical and Acoustical Properties of ION Conductivite Glasses

    Directory of Open Access Journals (Sweden)

    Igor Jamnicky

    2003-01-01

    Full Text Available The technological interest in fast ionic conductivity in glassy materials is increased in last years for various solid state electrochemical devices such as solid-state batteries, electrochronic displays, and sensors. The ion conductive glasses have several advantages comparing with crystalline materials because of their easy preparation, their stability, the large available compositionranges and reasonable cost. It is known that the investigation of conductivity spectra of ionic glasses can reflect the basic features ofthe relaxation and transport mechanisms of the mobile ions and the high ion conductivity at room temperature is the most important criterion which should be meet the fast ion conductive glasses. However, the relaxation and transport mechanisms can be investigated also by acoustic methods, that can have some advantages comparing to electrical ones as the high sensitivity, absence of contact phenomena and so on.In the contribution we present some electrical and acoustical properties of glasses prepared in the system CuI-CuBr-Cu20-(P20j+Mo03. The main purpose of the contribution is to contribute to the investigation of ion transport mechanisms in these fast ion conductive glasses and to determine the relation between electrical and acoustical properties considering the various glass compositions.

  2. Enhancing the absorption properties of acoustic porous plates by periodically embedding Helmholtz resonators.

    Science.gov (United States)

    Groby, J-P; Lagarrigue, C; Brouard, B; Dazel, O; Tournat, V; Nennig, B

    2015-01-01

    This paper studies the acoustical properties of hard-backed porous layers with periodically embedded air filled Helmholtz resonators. It is demonstrated that some enhancements in the acoustic absorption coefficient can be achieved in the viscous and inertial regimes at wavelengths much larger than the layer thickness. This enhancement is attributed to the excitation of two specific modes: Helmholtz resonance in the viscous regime and a trapped mode in the inertial regime. The enhancement in the absorption that is attributed to the Helmholtz resonance can be further improved when a small amount of porous material is removed from the resonator necks. In this way the frequency range in which these porous materials exhibit high values of the absorption coefficient can be extended by using Helmholtz resonators with a range of carefully tuned neck lengths.

  3. Measurements of Acoustic Properties of Porous and Granular Materials and Application to Vibration Control

    Science.gov (United States)

    Park, Junhong; Palumbo, Daniel L.

    2004-01-01

    For application of porous and granular materials to vibro-acoustic controls, a finite dynamic strength of the solid component (frame) is an important design factor. The primary goal of this study was to investigate structural vibration damping through this frame wave propagation for various poroelastic materials. A measurement method to investigate the vibration characteristics of the frame was proposed. The measured properties were found to follow closely the characteristics of the viscoelastic materials - the dynamic modulus increased with frequency and the degree of the frequency dependence was determined by its loss factor. The dynamic stiffness of hollow cylindrical beams containing porous and granular materials as damping treatment was measured also. The data were used to extract the damping materials characteristics using the Rayleigh-Ritz method. The results suggested that the acoustic structure interaction between the frame and the structure enhances the dissipation of the vibration energy significantly.

  4. [The analysis of increased physical load effect on microcirculation and acoustic properties of human limb skin].

    Science.gov (United States)

    Grebeniuk, L A

    2014-01-01

    Complex study of limb skin integument has been performed in 20 male "sportsmen of high qualification (track-and-field athletes and wrestlers of Graeco-Roman style) at the age of 17-25 years, as well as in inactive subjects of the same age. The results obtained by us evidence the variability of limb integumentary tissue acoustic properties in sportsmen as manifestation of adaptive response to regular increasedphysical loads experience by them every day. Some differences in microcirculation of skin integument has been established, first of all, those associated with reserve level--higher increase of capillary blood flow in leg skin during functional ischemic test and 66.2% exceeding capillary blood flow reserve index for leg in track-and-field athletes in comparison with that value in non-sportsmen. The speed of propagation of surface acoustic wave in leg skin during testing in different angular directions reliably exceeded the acoustic parameters of femoral integumentary tissue both in the track-and-field athletes and wrestlers examined, and in the subjects of non-sportsmen control group. The speed of propagation of surface acoustic wave in integumentary tissue of limb distal segments have been established to exceed those of proximal segments. When functional test was made in sportsmen for plasticity reserve reveal, modification of the shape of sound velocity envelope curve took place for the change in spatial position of the limb, evidencing the dynamicity of its elastic properties during performing movements of vital function and the presence of certain plastic reserve.

  5. 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.

  6. Electronic, elastic, acoustic and optical properties of cubic TiO{sub 2}: A DFT approach

    Energy Technology Data Exchange (ETDEWEB)

    Mahmood, Tariq, E-mail: tariq_mahmood78@hotmail.com [Research Center of Materials Science, School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Centre for High Energy Physics, University of the Punjab, Lahore 54590 (Pakistan); Cao, Chuanbao, E-mail: cbcao@bit.edu.cn [Research Center of Materials Science, School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Tahir, Muhammad; Idrees, Faryal [Research Center of Materials Science, School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Ahmed, Maqsood [Centre for High Energy Physics, University of the Punjab, Lahore 54590 (Pakistan); Tanveer, M.; Aslam, Imran; Usman, Zahid; Ali, Zulfiqar; Hussain, Sajad [Research Center of Materials Science, School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

    2013-07-01

    The electronic, elastic, acoustic and optical properties of cubic phases TiO{sub 2} fluorite and pyrite are investigated using the first principles calculations. We have employed five different exchange–correlation functions within the local density and generalized gradient approximations using the ultrasoft plane wave pseudopotential method. The calculated band structures of cubic-TiO{sub 2} elucidate that the TiO{sub 2} fluorite and pyrite are direct and indirect semiconductors in contrast to the previous findings. From our studied properties such as bulk and shear moduli, elastic constants C{sub 44} and Debye temperature for TiO{sub 2} fluorite and pyrite, we infer that both the cubic phases are not superhard materials and the pyrite phase is harder than fluorite. The longitudinal and transversal acoustic wave speeds for both phases in the directions [100], [110] and [111] are determined using the pre-calculated elastic constants. In addition, we also calculate the optical properties such as dielectric function, absorption spectrum, refractive index and energy loss function using the pre-optimized structure. On the observation of optical properties TiO{sub 2} fluorite phase turn out to be more photocatalytic than pyrite.

  7. 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 ...

  8. Acoustic tests of elastic and microplastic properties of V-Ti-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chernov, V.M. [Fiziko-Ehnergeticheskij Institut, Obninsk (Russian Federation); Rezvoushkin, A.V. [Fiziko-Ehnergeticheskij Institut, Obninsk (Russian Federation); Kardashev, B.K. [Ioffe Physico-Technical Inst., St. Petersburg (Russian Federation)

    1996-10-01

    The non-linear acoustic properties of V-10Ti-5Cr alloy before and after proton irradiation (dose 2.2 x 10{sup 14} p/cm{sup 2}) were investigated using a composite oscillator technique at longitudinal vibration frequencies of about 100 kHz. Acoustic parameters (decrement and resonance frequency) of the samples demonstrated noticeable amplitude dependencies of hysteretic type both in undeformed and deformed states. An unusual influence of plastical pre-straining on irradiated sample was found which resulted in small decreases in damping and increases in resonance frequency, and hence, of the elastic modulus. Damping in an irradiated sample was higher and its resonant frequency was lower as compared with a non-irradiated sample. This acoustic effect correlated with the results of microhardness and yield strength measurements. The experimental results are discussed in the framework of a model which predicts the creation by proton irradiation of defects which aid the motion of dislocations in V-alloys. (orig.).

  9. The Acoustic Properties of Suspended Sediment in Large Rivers: Consequences on ADCP Methods Applicability

    Directory of Open Access Journals (Sweden)

    Massimo Guerrero

    2016-01-01

    Full Text Available The use of echo-levels from Acoustic Doppler Current Profiler (ADCP recordings has become more and more common for estimating suspended bed-material and wash loads in rivers over the last decade. Empirical, semi-empirical and physical-based acoustic methods have been applied in different case studies, which provided relationships between scattering particles features derived from samples (i.e., concentration and grain size and corresponding backscattering strength and sound attenuation. These methods entail different assumptions regarding sediment heterogeneity in the ensonified volume (e.g., particle size distribution (PSD and spatial concentration gradient. Our work was to compare acoustic backscatter and attenuation properties of suspended sediments, sampled in the rivers Parana and Danube that represented rather different hydro-sedimentological conditions during the surveys. The Parana represents a large sandy river, characterized through a huge watershed and the typical bimodal PSD of sediment in suspension, while the Danube represents in the investigated reach an exposed sand-gravel bed and clay-silt particles transported in the water column in suspension. Sand and clay-silt concentrations clearly dominate the analyzed backscattering strength in the rivers Parana and Danube, respectively, with an effect of PSD level of sorting in the latter case. This comparison clarifies the extent of assumptions made, eventually advising on the actual possibility of applying certain ADCP methods, depending on the expected concentration gradients and PSD of suspended sediment to be investigated.

  10. Acoustic property reconstruction of a neonate Yangtze finless porpoise's (Neophocaena asiaeorientalis) head based on CT imaging.

    Science.gov (United States)

    Wei, Chong; Wang, Zhitao; Song, Zhongchang; Wang, Kexiong; Wang, Ding; Au, Whitlow W L; Zhang, Yu

    2015-01-01

    The reconstruction of the acoustic properties of a neonate finless porpoise's head was performed using X-ray computed tomography (CT). The head of the deceased neonate porpoise was also segmented across the body axis and cut into slices. The averaged sound velocity and density were measured, and the Hounsfield units (HU) of the corresponding slices were obtained from computed tomography scanning. A regression analysis was employed to show the linear relationships between the Hounsfield unit and both sound velocity and density of samples. Furthermore, the CT imaging data were used to compare the HU value, sound velocity, density and acoustic characteristic impedance of the main tissues in the porpoise's head. The results showed that the linear relationships between HU and both sound velocity and density were qualitatively consistent with previous studies on Indo-pacific humpback dolphins and Cuvier's beaked whales. However, there was no significant increase of the sound velocity and acoustic impedance from the inner core to the outer layer in this neonate finless porpoise's melon.

  11. Combined surface acoustic wave and surface plasmon resonance measurement of collagen and fibrinogen layer physical properties

    Directory of Open Access Journals (Sweden)

    J.-M. Friedt

    2016-12-01

    Full Text Available We use an instrument combining optical (surface plasmon resonance and acoustic (Love mode surface acoustic wave device real-time measurements on a same surface for the identification of water content in collagen and fibrinogen protein layers. After calibration of the surface acoustic wave device sensitivity by copper electrodeposition and surfactant adsorption, the bound mass and its physical properties – density and optical index – are extracted from the complementary measurement techniques and lead to thickness and water ratio values compatible with the observed signal shifts. Such results are especially usefully for protein layers with a high water content as shown here for collagen on an hydrophobic surface. We obtain the following results: collagen layers include 70±20% water and are 16±3 to 19±3 nm thick for bulk concentrations ranging from 30 to 300 μg/ml. Fibrinogen layers include 50±10% water for layer thicknesses in the 6±1.5 to 13±2 nm range when the bulk concentration is in the 46 to 460 μg/ml range.

  12. Characterizing riverbed sediment using high-frequency acoustics 1: spectral properties of scattering

    Science.gov (United States)

    Buscombe, Daniel D.; Grams, Paul E.; Kaplinski, Matt A.

    2014-01-01

    Bed-sediment classification using high-frequency hydro-acoustic instruments is challenging when sediments are spatially heterogeneous, which is often the case in rivers. The use of acoustic backscatter to classify sediments is an attractive alternative to analysis of topography because it is potentially sensitive to grain-scale roughness. Here, a new method is presented which uses high-frequency acoustic backscatter from multibeam sonar to classify heterogeneous riverbed sediments by type (sand, gravel,rock) continuously in space and at small spatial resolution. In this, the first of a pair of papers that examine the scattering signatures from a heterogeneous riverbed, methods are presented to construct spatially explicit maps of spectral properties from geo-referenced point clouds of geometrically and radiometrically corrected echoes. Backscatter power spectra are computed to produce scale and amplitude metrics that collectively characterize the length scales of stochastic measures of riverbed scattering, termed ‘stochastic geometries’. Backscatter aggregated over small spatial scales have spectra that obey a power-law. This apparently self-affine behavior could instead arise from morphological- and grain-scale roughnesses over multiple overlapping scales, or riverbed scattering being transitional between Rayleigh and geometric regimes. Relationships exist between stochastic geometries of backscatter and areas of rough and smooth sediments. However, no one parameter can uniquely characterize a particular substrate, nor definitively separate the relative contributions of roughness and acoustic impedance (hardness). Combinations of spectral quantities do, however, have the potential to delineate riverbed sediment patchiness, in a data-driven approach comparing backscatter with bed-sediment observations (which is the subject of part two of this manuscript).

  13. 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)

  14. Acoustic properties of silica aerogels from 400 mK to 400 K

    Science.gov (United States)

    Daughton, David R.; MacDonald, James; Mulders, Norbert

    2003-05-01

    Using acoustic resonant spectroscopy, we have studied the low-frequency elastic properties of silica aerogels with densities between 0.045 and 0.267 g/cm3 over a temperature range of 400 mK to 400 K. We observe a large change in the elastic moduli between 20 and 100 K, accompanied by a damping peak, and attribute this to a thermally activated relaxation process. Above 100 K, the elastic moduli increase linearly with temperature, a phenomenon normally associated with elastomers such as rubber, and indicative of a significant entropic contribution to the stiffness of the aerogels.

  15. Surface properties of solids and surface acoustic waves: Application to chemical sensors and layer characterization

    Science.gov (United States)

    Krylov, V. V.

    1995-09-01

    A general phenomenological approach is given for the description of mechanical surface properties of solids and their influence on surface acoustic wave propogation. Surface properties under consideration may be changes of the stress distribution in subsurface atomic layers, the presence of adsorbed gas molecules, surface degradation as a result of impacts from an aggressive environment, damage due to mechanical manufacturing or polishing, deposition of thin films or liquid layers, surface corrugations, etc. If the characteristic thickness of the affected layers is much less than the wavelengths of the propagating surface waves, then the effects of all these irregularities can be described by means of non-classical boundary conditions incorporating the integral surface parameters such as surface tension, surface moduli of elasticity and surface mass density. The effect of surface properties on the propagation of Rayleigh surface waves is analysed in comparison with the results of traditional approaches, in particular with Auld's energy perturbation method. One of the important implications of the above-mentioned boudnary conditions is that they are adequate for the description of the effect of rarely distributed adsorbed atoms or molecules. This allows, in particular, to obtain a rigorous theoretical description of chemical sensors using surface acoustic waves and to derive analytical expressions for their sensitivity.

  16. Diagnostics of elastic properties of a planar interface between two rough media using surface acoustic waves

    Science.gov (United States)

    Kokshaiskii, A. I.; Korobov, A. I.; Shirgina, N. V.

    2017-03-01

    The results of experimental studies on the nonlinear elastic properties of a planar interface between two media are presented—an optically polished glass substrate and flat samples with different degrees of roughness. The nonlinear elastic properties of the interfaces between two media were investigated by the spectral method using surface acoustic waves (SAWs). The effect of external pressure applied to the interface on the efficiency of the generation of the second SAW harmonic was studied. Using the measured amplitudes of the first and second harmonics of the SAW that passes along the interface, the second-order nonlinear acoustic parameter was calculated as a function of the external pressure applied to the sample at a fixed amplitude of a probing wave. It was revealed that the nonlinear parameter of the SAW is a nonmonotonic function of the pressure at the boundary. The results were analyzed on the basis of an elastic contact nonlinearity, and it is concluded that these results can be used in nondestructive testing for roughness and waviness of surfaces of flat solids.

  17. Acoustic properties of Kel F-800 copolymer up to 85 GPa.

    Science.gov (United States)

    Benjamin, Ari S; Ahart, Muhtar; Gramsch, Stephen A; Stevens, Lewis L; Orler, E Bruce; Dattelbaum, Dana M; Hemley, Russell J

    2012-07-07

    Acoustic properties of the fluorinated copolymer Kel F-800 were determined with Brillouin spectroscopy up to pressures of 85 GPa at 300 K. This research addresses outstanding issues in high-pressure polymer behavior, as to date the acoustic properties and equation of state of any polymer have not been determined above 20 GPa. We observed both longitudinal and transverse modes in all pressure domains, allowing us to calculate the C(11) and C(12) moduli, bulk, shear, and Young's moduli, and the density of Kel F-800 as a function of pressure. We found the behavior of the polymer with respect to all parameters to change drastically with pressure. As a result, we find that the data are best understood when split into two pressure regimes. At low pressures (less than ∼5 GPa), analysis of the room temperature isotherm with a semi-empirical equation of state yielded a zero-pressure bulk modulus K(o) and its derivative K(0) (') of 12.8 ± 0.8 GPa and 9.6 ± 0.7, respectively. The same analysis for the higher pressure data yielded values for K(o) and K(0) (') of 34.9 ± 1.7 GPa and 5.1 ± 0.1, respectively. We discuss this significant difference in behavior with reference to the concept of effective free volume collapse.

  18. Characterizing riverbed sediment using high-frequency acoustics: 1. Spectral properties of scattering

    Science.gov (United States)

    Buscombe, D.; Grams, P. E.; Kaplinski, M. A.

    2014-12-01

    Bed sediment classification using high-frequency hydroacoustic instruments is challenging when sediments are spatially heterogeneous, which is often the case in rivers. The use of acoustic backscatter to classify sediments is an attractive alternative to analysis of topography because it is potentially sensitive to grain scale roughness. Here a new method is presented which uses high-frequency acoustic backscatter from multibeam sonar to classify heterogeneous riverbed sediments by type (sand, gravel, and rock) continuously in space and at small spatial resolution. In this, the first of a pair of papers that examine the scattering signatures from a heterogeneous riverbed, methods are presented to construct spatially explicit maps of spectral properties from georeferenced point clouds of geometrically and radiometrically corrected echoes. Backscatter power spectra are computed to produce scale and amplitude metrics that collectively characterize the length scales of stochastic measures of riverbed scattering, termed "stochastic geometries." Backscatter aggregated over small spatial scales have spectra that obey a power law. This apparently self-affine behavior could instead arise from morphological scale and grain scale roughnesses over multiple overlapping scales or riverbed scattering being transitional between Rayleigh and geometric regimes. Relationships exist between stochastic geometries of backscatter and areas of rough and smooth sediments. However, no one parameter can uniquely characterize a particular substrate nor definitively separate the relative contributions of roughness and acoustic impedance (hardness). Combinations of spectral quantities do, however, have the potential to delineate riverbed sediment patchiness, in a data-driven approach comparing backscatter with bed sediment observations (which is the subject of part two of this manuscript).

  19. Effects of nasalance on the acoustical properties of the tenor passaggio and the head voice

    Science.gov (United States)

    Perna, Nicholas Kevin

    This study aims to measure the effect that nasality has on the acoustical properties of the tenor passaggio and head voice. Not to be confused with forward resonance, nasality here will be defined as nasalance, the reading of a Nasometer, or the percentage of nasal and oral airflow during phonation. A previous study by Peer Birch et al. has shown that professional tenors used higher percentages of nasalance through their passaggio. They hypothesized that tenors used nasalance to make slight timbral adjustments as they ascended through passaggio. Other well respected authors including Richard Miller and William McIver have claimed that teaching registration issues is the most important component of training young tenors. It seemed logical to measure the acoustic effects of nasalance on the tenor passaggio and head voice. Eight professional operatic tenors participated as subjects performing numerous vocal exercises that demonstrated various registration events. These examples were recorded and analyzed using a Nasometer and Voce Vista Pro Software. Tenors did generally show an increase of nasalance during an ascending B-flat major scale on the vowels [i] and [u]. Perhaps the most revealing result was that six of seven tenors showed at least a 5-10% increase in nasalance on the note after their primary register transition on the vowel of [a]. It is suggested that this phenomenon receive further empirical scrutiny, because, if true, pedagogues could use nasalance as a tool for helping a young tenor ascend through his passaggio.

  20. Brillouin-scattering determination of the acoustic properties and their pressure dependence for three polymeric elastomers

    Science.gov (United States)

    Stevens, Lewis L.; Orler, E. Bruce; Dattelbaum, Dana M.; Ahart, Muhtar; Hemley, Russell J.

    2007-09-01

    The acoustic properties of three polymer elastomers, a cross-linked poly(dimethylsiloxane) (Sylgard® 184), a cross-linked terpolymer poly(ethylene-vinyl acetate-vinyl alcohol), and a segmented thermoplastic poly(ester urethane) copolymer (Estane® 5703), have been measured from ambient pressure to approximately 12GPa by using Brillouin scattering in high-pressure diamond anvil cells. The Brillouin-scattering technique is a powerful tool for aiding in the determination of equations of state for a variety of materials, but to date has not been applied to polymers at pressures exceeding a few kilobars. For the three elastomers, both transverse and longitudinal acoustic modes were observed, though the transverse modes were observed only at elevated pressures (>0.7GPa) in all cases. From the Brillouin frequency shifts, longitudinal and transverse sound speeds were calculated, as were the C11 and C12 elastic constants, bulk, shear, and Young's moduli, and Poisson's ratios, and their respective pressure dependencies. P-V isotherms were then constructed, and fit to several empirical/semiempirical equations of state to extract the isothermal bulk modulus and its pressure derivative for each material. Finally, the lack of shear waves observed for any polymer at ambient pressure, and the pressure dependency of their appearance is discussed with regard to instrumental and material considerations.

  1. Study on acoustical properties of sintered bronze porous material for transient exhaust noise of pneumatic system

    Science.gov (United States)

    Li, Jingxiang; Zhao, Shengdun; Ishihara, Kunihiko

    2013-05-01

    A novel approach is presented to study the acoustical properties of sintered bronze material, especially used to suppress the transient noise generated by the pneumatic exhaust of pneumatic friction clutch and brake (PFC/B) systems. The transient exhaust noise is impulsive and harmful due to the large sound pressure level (SPL) that has high-frequency. In this paper, the exhaust noise is related to the transient impulsive exhaust, which is described by a one-dimensional aerodynamic model combining with a pressure drop expression of the Ergun equation. A relation of flow parameters and sound source is set up. Additionally, the piston acoustic source approximation of sintered bronze silencer with cylindrical geometry is presented to predict SPL spectrum at a far-field observation point. A semi-phenomenological model is introduced to analyze the sound propagation and reduction in the sintered bronze materials assumed as an equivalent fluid with rigid frame. Experiment results under different initial cylinder pressures are shown to corroborate the validity of the proposed aerodynamic model. In addition, the calculated sound pressures according to the equivalent sound source are compared with the measured noise signals both in time-domain and frequency-domain. Influences of porosity of the sintered bronze material are also discussed.

  2. The effect of microstructural variation on the mechanical and acoustic properties of silicon carbide

    Science.gov (United States)

    Slusark, Douglas Michael

    Silicon carbide ceramic materials have many beneficial properties which have led to their adoption in various industrial uses, including its application as an armor material. This is due to the high hardness and stiffness of these materials, as well as a low relative density. The homogeneity of the final properties depends upon the processing history of the material. Factors which affect this include the need for high temperatures and sintering additives to achieve densification, as well as the presence of additive agglomerates and pressing artifacts within the green compact. This dissertation seeks to determine the effect which microstructural variability has on the acoustic and mechanical properties of sintered silicon carbide materials. Sample sets examined included commercially produced, pressurelessly sintered tiles, as well as additional, targeted tiles which were specifically produced for evaluation in this study. Production of these targeted samples was carried out such that particular aspects of the microstructure were emphasized. These included tiles which were fired with an excess of boron sintering aid as well as tiles which had been pressed to a reduced green body density and then fired. The sample evaluation procedure which was developed incorporated non destructive evaluation methods, mechanical testing, and both fractographic and image analysis of fractured and polished sections. Non destructive evaluation of the tiles was carried out by Archimedes density and ultrasound scanning at 20 MHz to determine the acoustic attenuation coefficient. Selected samples were chosen for machining into ASTM B-type bend bars on which 4-pt flexure testing was performed. Strength limiting features were designated for each sample set. The correlation between acoustic attenuation coefficient and quasi-static strength was examined both qualitatively and quantitatively. This was done by comparing the primary fracture location of flexure bars to features within the

  3. Acoustic Properties Predict Perception of Unfamiliar Dutch Vowels by Adult Australian English and Peruvian Spanish Listeners

    Science.gov (United States)

    Alispahic, Samra; Mulak, Karen E.; Escudero, Paola

    2017-01-01

    Research suggests that the size of the second language (L2) vowel inventory relative to the native (L1) inventory may affect the discrimination and acquisition of L2 vowels. Models of non-native and L2 vowel perception stipulate that naïve listeners' non-native and L2 perceptual patterns may be predicted by the relationship in vowel inventory size between the L1 and the L2. Specifically, having a smaller L1 vowel inventory than the L2 impedes L2 vowel perception, while having a larger one often facilitates it. However, the Second Language Linguistic Perception (L2LP) model specifies that it is the L1–L2 acoustic relationships that predict non-native and L2 vowel perception, regardless of L1 vowel inventory. To test the effects of vowel inventory size vs. acoustic properties on non-native vowel perception, we compared XAB discrimination and categorization of five Dutch vowel contrasts between monolinguals whose L1 contains more (Australian English) or fewer (Peruvian Spanish) vowels than Dutch. No effect of language background was found, suggesting that L1 inventory size alone did not account for performance. Instead, participants in both language groups were more accurate in discriminating contrasts that were predicted to be perceptually easy based on L1–L2 acoustic relationships, and were less accurate for contrasts likewise predicted to be difficult. Further, cross-language discriminant analyses predicted listeners' categorization patterns which in turn predicted listeners' discrimination difficulty. Our results show that listeners with larger vowel inventories appear to activate multiple native categories as reflected in lower accuracy scores for some Dutch vowels, while listeners with a smaller vowel inventory seem to have higher accuracy scores for those same vowels. In line with the L2LP model, these findings demonstrate that L1–L2 acoustic relationships better predict non-native and L2 perceptual performance and that inventory size alone is not a good

  4. Development of a New Apparatus for Investigating Acoustic Effects on Hydraulic Properties of Low-Permeability Geo-Materials

    Science.gov (United States)

    Nakajima, H.; Sawada, A.; Sugita, H.; Takeda, M.; Komai, T.; Zhang, M.

    2006-12-01

    feasibility of the EASD method and to obtain the fundamental but important knowledge for the design of this method, it is first necessary to understand the effects of acoustic wave application on pore water flow behavior. A new apparatus is developed to investigate the effects of acoustic wave on hydraulic properties of soil sample. This test apparatus enables to confine a cylindrical specimen under hydrostatic pressure conditions and to apply acoustic wave simultaneously. Preliminary results associated with the effects of acoustic wave frequency on changes of permeability of kaolin clay samples are illustrated in this report. A program investigating the effects of electricity and pore water chemistry on efficiency of decontamination using the same samples is also ongoing and briefly presented. The two strategies for enhancing the efficiency of remediation for low permeable soils will be combined in the near future

  5. Effects of Perforation on Rigid PU Foam Plates: Acoustic and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Jia-Horng Lin

    2016-12-01

    Full Text Available Factories today are equipped with diverse mechanical equipment in response to rapid technological and industrial developments. Industrial areas located near residential neighborhoods cause massive environmental problems. In particular, noise pollution results in physical and psychological discomfort, and is a seen as invisible and inevitable problem. Thus, noise reduction is a critical and urgent matter. In this study, rigid polyurethane (PU foam plates undergo perforation using a tapping machine. The mechanical and acoustic properties of these perforated plates as related to perforation rate and perforation depth are evaluated in terms of compression strength, drop-weight impact strength, and sound absorption coefficient. Experimental results indicate that applying the perforation process endows the rigid PU foaming plates with greater load absorption and better sound absorption at medium and high frequencies.

  6. An experimental study of the effects of water repellant treatment on the acoustic properties of Kevlar

    Science.gov (United States)

    Smith, C. D.; Parrott, T. L.

    1978-01-01

    The treatment consisted of immersing samples of Kevlar in a solution of distilled water and Zepel. The samples were then drained, dried in a circulating over, and cured. Flow resistance tests showed approximately one percent decrease in flow resistance of the samples. Also there was a density increase of about three percent. It was found that the treatment caused a change in the texture of the samples. There were significant changes in the acoustic properties of the treated Kevlar over the frequency range 0.5 to 3.5 kHz. In general it was found that the propagation constant and characteristic impedance increased with increasing frequency. The real and imaginary components of the propagation constant for the treated Kevlar exhibited a decrease of 8 to 12 percent relative to that for the untreated Kevlar at the higher frequencies. The magnitude of the reactance component of the characteristic impedance decreased by about 40 percent at the higher frequencies.

  7. Conservation properties of the trapezoidal rule in linear time domain analysis of acoustics and structures

    CERN Document Server

    Nandy, Arup Kumar

    2014-01-01

    The trapezoidal rule, which is a special case of the Newmark family of algorithms, is one of the most widely used methods for transient hyperbolic problems. In this work, we show that this rule conserves linear and angular momenta and energy in the case of undamped linear elastodynamics problems, and an `energy-like measure' in the case of undamped acoustic problems. These conservation properties, thus, provide a rational basis for using this algorithm. In linear elastodynamics problems, variants of the trapezoidal rule that incorporate `high-frequency' dissipation are often used, since the higher frequencies, which are not approximated properly by the standard displacement-based approach, often result in unphysical behavior. Instead of modifying the trapezoidal algorithm, we propose using a hybrid finite element framework for constructing the stiffness matrix. Hybrid finite elements, which are based on a two-field variational formulation involving displacement and stresses, are known to approximate the eigen...

  8. Method for noninvasive determination of acoustic properties of fluids inside pipes

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-08-02

    A method for determining the composition of fluids flowing through pipes from noninvasive measurements of acoustic properties of the fluid is described. The method includes exciting a first transducer located on the external surface of the pipe through which the fluid under investigation is flowing, to generate an ultrasound chirp signal, as opposed to conventional pulses. The chirp signal is received by a second transducer disposed on the external surface of the pipe opposing the location of the first transducer, from which the transit time through the fluid is determined and the sound speed of the ultrasound in the fluid is calculated. The composition of a fluid is calculated from the sound speed therein. The fluid density may also be derived from measurements of sound attenuation. Several signal processing approaches are described for extracting the transit time information from the data with the effects of the pipe wall having been subtracted.

  9. Acoustic properties of bovine cancellous bone from 0.5 to 1.5 MHz

    Science.gov (United States)

    Lee, Kang Il; Roh, Heui-Seol; Yoon, S. W.

    2002-05-01

    Most previous studies using ultrasound for the diagnosis of osteoporosis have employed ultrasound in the frequency range from 0.2 to 1 MHz. Acoustic properties of 14 defatted bovine cancellous bone specimens were investigated in vitro. Speed of sound (SOS) and broadband ultrasonic attenuation (BUA) were measured using two matched pairs of transducers with the center frequencies of 1 and 2.25 MHz, respectively, in order to cover a broad frequency range from 0.5 to 1.5 MHz. In this frequency range, SOS and BUA show significant linear positive correlations with apparent bone density. These results suggest that the frequency range from 0.5 to 1.5 MHz may also be useful in the diagnosis of osteoporosis. [Work supported by BK21 Program, KRF (KRF-2000-015-DP0718), and KOSEF (KOSEF-2000-0238-100) in Korea.] a)For (Biomedical Ultrasound/Bioresponse to Vibration) Best Student Paper Award.

  10. Influence of Acoustic and Electromagnetic Actions on the Properties of Aqueous Nanoparticle Dispersions Used as Tempering Liquids for Dental Cement

    Science.gov (United States)

    Azharonok, V. V.; Belous, N. Kh.; Rodtsevich, S. P.; Goncharik, S. V.; Chubrik, N. N.; Koshevar, V. D.; Lopat‧ko, K. G.; Aftandilyants, E. G.; Veklich, A. N.; Boretskii, V. F.; Orlovich, A. I.

    2016-05-01

    The authors have studied the physicochemical properties of aqueous dispersions containing carbon, silver, and iron nanoparticles which were produced by elastic-spark synthesis under the conditions of subaqueous spark discharge, and also the influence of preliminary acoustic and high-frequency electromagnetic action on them and the change in the functional indices of the glass-ionomer cement tempered by these dispersions.

  11. Acoustic properties of porous concrete made from arlite and vermiculite lightweight aggregates

    Directory of Open Access Journals (Sweden)

    Carbajo, J.

    2015-12-01

    Full Text Available The use of sustainable materials is becoming a common practice for noise abatement in building and civil engineering industries. In this context, many applications have been found for porous concrete made from lightweight aggregates. This work investigates the acoustic properties of porous concrete made from arlite and vermiculite lightweight aggregates. These natural resources can still be regarded as sustainable since they can be recycled and do not generate environmentally hazardous waste. The experimental basis used consists of different type specimens whose acoustic performance is assessed in an impedance tube. Additionally, a simple theoretical model for granular porous media, based on parameters measurable with basic experimental procedures, is adopted to predict the acoustic properties of the prepared mixes. The theoretical predictions compare well with the absorption measurements. Preliminary results show the good absorption capability of these materials, making them a promising alternative to traditional porous concrete solutions.El uso de materiales sostenibles se está convirtiendo en una práctica común para la reducción de ruido en las industrias de la edificación e ingeniería civil. Este trabajo investiga las propiedades acústicas de hormigón poroso fabricado a partir de áridos ligeros de arlita y vermiculita. Estos recursos naturales todavía pueden considerarse sostenibles ya que pueden ser reciclados y no generan residuos peligrosos para el medio ambiente. La base experimental utilizada se compone de especímenes de diferente tipo cuyas prestaciones acústicas se evalúan en un tubo de impedancia. Adicionalmente, se ha adoptado un modelo teórico simple para medios porosos granulares, basado en parámetros medibles con procedimientos experimentales básicos, con objeto de predecir las propiedades acústicas de las mezclas preparadas. Las predicciones teóricas muestran una buena concordancia con las medidas de absorci

  12. Propagation Properties of Quasi-longitudinal Leaky Surface Acoustic Wave on Y-Rotated Cut Quartz Substrates

    Institute of Scientific and Technical Information of China (English)

    TONG Xiao-Jun; WANG Wei-Biao; ZHOU Ran; ZHANG De; QIN Hou-Rong

    2000-01-01

    Propagation properties of the quasi-longitudinal leaky surface acoustic wave (QLLSAW) along different directions on Y-rotated cut quartz substrates, such as on the 34°, 36°, 42° Y-rotated cut, are investigated. The advantages of the QLLSAW along some directions include low propagation attenuation (less than 10-4dB/λ), small power flow deviation and high phase velocity which can be up to 7000 m/s. A novel propagation direction of the quasi longitudinal leaky surface acoustic wave with the theoretical temperature coefficient of delay of 0.508 ppm/°C is proposed.

  13. Nonlinear acoustic properties of ex vivo bovine liver and the effects of temperature and denaturation.

    Science.gov (United States)

    Jackson, E J; Coussios, C-C; Cleveland, R O

    2014-06-21

    Thermal ablation by high intensity focused ultrasound (HIFU) has a great potential for the non-invasive treatment of solid tumours. Due to the high pressure amplitudes involved, nonlinear acoustic effects must be understood and the relevant medium property is the parameter of nonlinearity B/A. Here, B/A was measured in ex vivo bovine liver, over a heating/cooling cycle replicating temperatures reached during HIFU ablation, adapting a finite amplitude insertion technique, which also allowed for measurement of sound-speed and attenuation. The method measures the nonlinear progression of a plane wave through liver and B/A was chosen so that numerical simulations matched the measured waveforms. To create plane-wave conditions, sinusoidal bursts were transmitted by a 100 mm diameter 1.125 MHz unfocused transducer and measured using a 15 mm diameter 2.25 MHz broadband transducer in the near field. Attenuation and sound-speed were calculated using a reflected pulse from the smaller transducer using the larger transducer as the reflecting interface. Results showed that attenuation initially decreased with heating then increased after denaturation, the sound-speed initially increased with temperature and then decreased, and B/A showed an increase with temperature but no significant post-heating change. The B/A data disagree with other reports that show a significant change and we suggest that any nonlinear enhancement in the received ultrasound signal post-treatment is likely due to acoustic cavitation rather than changes in tissue nonlinearity.

  14. Passive element enriched photoacoustic computed tomography (PER PACT) for simultaneous imaging of acoustic propagation properties and light absorption.

    Science.gov (United States)

    Jose, Jithin; Willemink, Rene G H; Resink, Steffen; Piras, Daniele; van Hespen, J C G; Slump, Cornelis H; Steenbergen, Wiendelt; van Leeuwen, Ton G; Manohar, Srirang

    2011-01-31

    We present a 'hybrid' imaging approach which can image both light absorption properties and acoustic transmission properties of an object in a two-dimensional slice using a computed tomography (CT) photoacoustic imager. The ultrasound transmission measurement method uses a strong optical absorber of small cross-section placed in the path of the light illuminating the sample. This absorber, which we call a passive element acts as a source of ultrasound. The interaction of ultrasound with the sample can be measured in transmission, using the same ultrasound detector used for photoacoustics. Such measurements are made at various angles around the sample in a CT approach. Images of the ultrasound propagation parameters, attenuation and speed of sound, can be reconstructed by inversion of a measurement model. We validate the method on specially designed phantoms and biological specimens. The obtained images are quantitative in terms of the shape, size, location, and acoustic properties of the examined heterogeneities.

  15. Combined experimental-numerical characterisation of the vibro-acoustic properties of lightweight panels

    OpenAIRE

    De jonckheere, Stijn; Vivolo, Marianna; Pluymers, Bert; Vandepitte, Dirk; Desmet, Wim

    2012-01-01

    The presented paper focuses on a combined approach, using a new type of measurement setup, which has been specifically developed for examining the vibro-acoustic behaviour of lightweight panels and the Wave Based Method (WBM) for the numerical simulation of vibro-acoustic problems. The setup consists of a concrete cavity of 0.83 m³ which can host test specimens of variable size and thickness. It allows for both structural and acoustical excitation and measurement acquisition. Among others,...

  16. Microbial-Induced Heterogeneity in the Acoustic Properties of Porous Media

    Science.gov (United States)

    Acoustic wave data were acquired over a two-dimensional region of a microbial-stimulated sand column and an unstimulated sand column to assess the spatiotemporal changes in a porous medium caused by microbial growth and biofilm formation. The acoustic signals from the unstimulate...

  17. The effect of magnetic nanoparticles on the acoustic properties of tissue-mimicking agar-gel phantoms

    Science.gov (United States)

    Józefczak, A.; Kaczmarek, K.; Kubovčíková, M.; Rozynek, Z.; Hornowski, T.

    2017-06-01

    In ultrasonic hyperthermia, ultrasound-induced heating is achieved by the absorption of wave energy and its conversion into heat. The effectiveness of ultrasounds can be improved by using sonosensitisers that greatly attenuate ultrasonic waves and then dissipate the acquired energy in the form of heat. One possible candidate for such a sonosensitiser are superparamagnetic iron oxide nanoparticles. Here, we used magnetic nanoparticles embedded in a tissue-mimicking agar-gel matrix. Such tissue-mimicking phantoms possess acoustic properties similar to those of real tissues, and are used as a tool for performance testing and optimisation of medical ultrasound systems. In this work, we studied the effect of magnetic nanoparticles on the acoustic properties of agar-gel phantoms, including the attenuation of ultrasonic waves.

  18. Numerical analysis of the vibroacoustic properties of plates with embedded grids of acoustic black holes.

    Science.gov (United States)

    Conlon, Stephen C; Fahnline, John B; Semperlotti, Fabio

    2015-01-01

    The concept of an Acoustic Black Hole (ABH) has been developed and exploited as an approach for passively attenuating structural vibration. The basic principle of the ABH relies on proper tailoring of the structure geometrical properties in order to produce a gradual reduction of the flexural wave speed, theoretically approaching zero. For practical systems the idealized "zero" wave speed condition cannot be achieved so the structural areas of low wave speed are treated with surface damping layers to allow the ABH to approach the idealized dissipation level. In this work, an investigation was conducted to assess the effects that distributions of ABHs embedded in plate-like structures have on both vibration and structure radiated sound, focusing on characterizing and improving low frequency performance. Finite Element and Boundary Element models were used to assess the vibration response and radiated sound power performance of several plate configurations, comparing baseline uniform plates with embedded periodic ABH designs. The computed modal loss factors showed the importance of the ABH unit cell low order modes in the overall vibration reduction effectiveness of the embedded ABH plates at low frequencies where the free plate bending wavelengths are longer than the scale of the ABH.

  19. Improvement of Date Palm Fibre Acoustic Properties Using Perforated Plate, Woven Cotton Cloth and Polyester

    Directory of Open Access Journals (Sweden)

    Lamyaa Abd AL Rahman

    2013-12-01

    Full Text Available The aim of this study was to explore the effect of date palm fibre as backing on sound absorption using three types of perforation plates and porous layers. The predicted results were verified by measurements conducted in an impedance tube on normal incidence sound absorption of 30 and 50 mm-thick date palm fibre and backing that may have positive effect are elaborated in this study. It describes how the porous materials of date palm fibre absorber panel can change the absorption behavior. The results obtained show that perforation plate, porous layers have a significant effect on absorption, whereas thickness panel have considerable effect too. This further indicate that three types have been used and also supported can be powerfully exploited to improve the absorption of date palm fibre and at the same time a reasonable thickness chosen, would be very efficient for absorption sound. An example is presented to show the approaches of enhancing the absorption, by utilizing the advantage of modification in the absorption sound. It exhibits that properly chosen perforation ratio along with suitable sample thickness can increase the absorption as well as the selected porous layers. It was evident that these can be powerfully exploited to improve the absorption of date palm fibre. Three types of perforation plate, porous layers were used to improve acoustic properties of date palm fibre. This means the innovative fibre becomes more active and efficient, plus it is renewable, waste material and very light compared to industrial substances.

  20. The effect of particle shape and size distribution on the acoustical properties of mixtures of hemp particles.

    Science.gov (United States)

    Glé, Philippe; Gourdon, Emmanuel; Arnaud, Laurent; Horoshenkov, Kirill-V; Khan, Amir

    2013-12-01

    Hemp concrete is an attractive alternative to traditional materials used in building construction. It has a very low environmental impact, and it is characterized by high thermal insulation. Hemp aggregate particles are parallelepiped in shape and can be organized in a plurality of ways to create a considerable proportion of open pores with a complex connectivity pattern, the acoustical properties of which have never been examined systematically. Therefore this paper is focused on the fundamental understanding of the relations between the particle shape and size distribution, pore size distribution, and the acoustical properties of the resultant porous material mixture. The sound absorption and the transmission loss of various hemp aggregates is characterized using laboratory experiments and three theoretical models. These models are used to relate the particle size distribution to the pore size distribution. It is shown that the shape of particles and particle size control the pore size distribution and tortuosity in shiv. These properties in turn relate directly to the observed acoustical behavior.

  1. Acoustic Imaging of Microstructure and Evaluation of the Adhesive's Physical, Mechanical and Chemical Properties Changes at Different Cure States

    Science.gov (United States)

    Severina, I. A.; Fabre, A. J.; Maeva, E. Yu.

    Epoxy thermoset adhesives transform during cure from liquid state into the highly cross-linked solid. Cure state of the material depends on condition of the reaction (temperature, pressure, time etc.) and resin/hardener ratio. It is known that the cure degree of the adhesive correlates with adhesion strength, which is critical for structural adhesives used in automotive, aerospace and marine industries. In this work, characterization of cure process of the adhesive with acoustic methods is presented. Evolution of the acoustic and elastic properties (attenuation, sound velocity, density, elastic moduli) during cure reaction was monitored in relation to the substantial physical and chemical changes of the material. These macro parameters of the adhesive were compared with the material's microstructure obtained by high-resolution acoustic microscopy technique in frequencies range of 50-400 MHz. Development of the microstructure of the adhesive as it cures at different conditions has been investigated. Appearance and development of the granular structure on the adhesive interface during cure reaction has been demonstrated. Acoustic images were analyzed by mathematical method to quantitatively characterize distribution of the adhesive's components. Statistical analysis of such images provides an accurate quantitative measure of the degree of cure of such samples. Research results presented in this paper can be useful as a basis for non-destructive evaluation of the adhesive materials

  2. Tissue-Mimicking Materials Using Segmented Polyurethane Gel and Their Acoustic Properties

    Science.gov (United States)

    Yoshida, Tomoji; Tanaka, Kouhei; Kondo, Toshio; Yasukawa, Kazuhiro; Miyamoto, Nobuaki; Taniguchi, Masahiko; Shikinami, Yasuo

    2012-07-01

    Accurate testing of an instrument by phantoms requires a tissue-mimicking material that has the acoustic velocity and density defined in the International Electrotechnical Commission (IEC) standard, and furthermore the tissue-mimicking material must be stable over time. To achieve the tissue-mimicking materials with the desired acoustic velocity and density defined in the IEC standard, new materials have been developed. The form of tissue-mimicking materials reported comprised polystyrene and poly(methyl methacrylate) (PMMA) particles dispersed in segmented polyurethane gel. They were stable over a period of 40 days and the changes in weight and acoustic velocity did not exceed 0.5%.

  3. Peculiar transmission property of acoustic waves in a one-dimensional layered phononic crystal

    Science.gov (United States)

    Zhao, Degang; Wang, Wengang; Liu, Zhengyou; Shi, Jing; Wen, Weijia

    2007-03-01

    In this article, we report both theoretical calculation and experimental observation of acoustic waves abnormally through a one-dimensional layered transmitted phononic crystal at frequencies within the band gap into a material of large acoustic impedance mismatch, with an efficiency as high as unity. The transmission peaks can be interpreted as a result of the interference of acoustic waves reflected from all periodically aligned interfaces. The condition for the appearance of peaks is analyzed in detail and the optimized layer number is given for different configurations.

  4. 聚酰亚胺泡沫吸声性能与理论分析%Acoustic Absorption Properties and Theoretics of Polyimide Foams

    Institute of Scientific and Technical Information of China (English)

    潘丕昌; 詹茂盛; 沈燕侠; 王凯

    2009-01-01

    采用前驱体微球法制备闭孔聚酰亚胺泡沫,并对其吸声性能进行了研究.结果表明,闭孔聚酰亚胺泡沫具有共振吸声特点;对闭孔聚酰亚胺泡沫的吸声系数进行了理论推导,研究了泡沫厚度对泡沫吸声性能的影响,分析了聚酰亚胺泡沫的吸声理论;采用闭孔泡沫与开孔泡沫组合后,泡沫整体吸声性能显著提高.%The closed cell polyimide foams were fabricated by foaming the precursor balloons, and the foams' acoustic absorption properties were tested. The results show that the acoustic absorption properties of closed cell polyimide foams have the typical resonance acoustic absorption characteristic. The acoustic absorption properties of polyimide foams were researched, and the influence of thickness and density on its acoustic absorption properties were also studied, the acoustic absorption theoretics of polyimide foams was analyzed. The combination of closed cell and open cell polyimide foams can notable enhance the acoustic absorption coefficient.

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

    Energy Technology Data Exchange (ETDEWEB)

    Thurman E. Scott, Jr., Ph.D.; Younane Abousleiman, Ph.D.; Musharraf Zaman, Ph.D., P.E.

    2001-07-01

    Mechanically weak formations, such as chalks, high porosity sandstones, and marine sediments, pose significant problems for oil and gas operators. Problems such as compaction, subsidence, and loss of permeability can affect reservoir production operations. For example, the unexpected subsidence of the Ekofisk chalk in the North Sea required over one billion dollars to re-engineer production facilities to account for losses created during that compaction (Sulak 1991). Another problem in weak formations is that of shallow water flows (SWF). Deep water drilling operations sometimes encounter cases where the marine sediments, at shallow depths just below the seafloor, begin to uncontrollably flow up and around the drill pipe. SWF problems created a loss of $150 million for the Ursa development project in the U.S. Gulf Coast SWF (Furlow 1998a,b; 1999a,b). The goal of this project is to provide a database on both the rock mechanical properties and the geophysical properties of weak rocks and sediments. These could be used by oil and gas companies to detect, evaluate, and alleviate potential production and drilling problems. The results will be useful in, for example, pre-drill detection of events such as SWF's by allowing a correlation of seismic data (such as hazard surveys) to rock mechanical properties. The data sets could also be useful for 4-D monitoring of the compaction and subsidence of an existing reservoir and imaging the zones of damage. During the second quarter of the project the research team has: (1) completed acoustic sensor construction, (2) conducted reconnaissance tests to map the deformational behaviors of the various rocks, (3) developed a sample assembly for the measurement of dynamic elastic and poroelastic parameters during triaxial testing, and (4) conducted a detailed review of the scientific literature and compiled a bibliography of that review. During the first quarter of the project the research team acquired several rock types for

  6. Comparative acoustic performance and mechanical properties of silk membranes for the repair of chronic tympanic membrane perforations.

    Science.gov (United States)

    Allardyce, Benjamin J; Rajkhowa, Rangam; Dilley, Rodney J; Xie, Zhigang; Campbell, Luke; Keating, Adrian; Atlas, Marcus D; von Unge, Magnus; Wang, Xungai

    2016-12-01

    The acoustic and mechanical properties of silk membranes of different thicknesses were tested to determine their suitability as a repair material for tympanic membrane perforations. Membranes of different thickness (10-100μm) were tested to determine their frequency response and their resistance to pressure loads in a simulated ear canal model. Their mechanical rigidity to pressure loads was confirmed by tensile testing. These membranes were tested alongside animal cartilage, currently the strongest available myringoplasty graft as well as paper, which is commonly used for simpler procedures. Silk membranes showed resonant frequencies within the human hearing range and a higher vibrational amplitude than cartilage, suggesting that silk may offer good acoustic energy transfer characteristics. Silk membranes were also highly resistant to simulated pressure changes in the middle ear, suggesting they can resist retraction, a common cause of graft failure resulting from chronic negative pressures in the middle ear. Part of this strength can be explained by the substantially higher modulus of silk films compared with cartilage. This allows for the production of films that are much thinner than cartilage, with superior acoustic properties, but that still provide the same level of mechanical support as thicker cartilage. Together, these in vitro results suggest that silk membranes may provide good hearing outcomes while offering similar levels of mechanical support to the reconstructed middle ear.

  7. A statistical characterization method for damping material properties and its application to structural-acoustic system design

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Byung C. [University of Maryland, College Park (United States); Lee, Doo Ho [Dongeui University, Busan (Korea, Republic of); Youn, Byeng D. [Seoul National University, Seoul (Korea, Republic of); Lee, Soo Bum [University of Notre Dame, Notre Dame (United States)

    2011-08-15

    The performance of surface damping treatments may vary once the surface is exposed to a wide range of temperatures, because the performance of viscoelastic damping material is highly dependent on operational temperature. In addition, experimental data for dynamic responses of viscoelastic material are inherently random, which makes it difficult to design a robust damping layout. In this paper a statistical modeling procedure with a statistical calibration method is suggested for the variability characterization of viscoelastic damping material in constrained-layer damping structures. First, the viscoelastic material property is decomposed into two sources: (I) a random complex modulus due to operational temperature variability, and (II) experimental/model errors in the complex modulus. Next, the variability in the damping material property is obtained using the statistical calibration method by solving an unconstrained optimization problem with a likelihood function metric. Two case studies are considered to show the influence of the material variability on the acoustic performances in the structural-acoustic systems. It is shown that the variability of the damping material is propagated to that of the acoustic performances in the systems. Finally, robust and reliable damping layout designs of the two case studies are obtained through the reliability-based design optimization (RBDO) amidst severe variability in operational temperature and the damping material.

  8. Piezoelectric Ca3NbGa3Si2O14 crystal: crystal growth, piezoelectric and acoustic properties

    Science.gov (United States)

    Roshchupkin, Dmitry; Ortega, Luc; Plotitcyna, Olga; Erko, Alexei; Zizak, Ivo; Vadilonga, Simone; Irzhak, Dmitry; Emelin, Evgenii; Buzanov, Oleg; Leitenberger, Wolfram

    2016-08-01

    Ca3NbGa3Si2O14 (CNGS), a five-component crystal of lanthanum-gallium silicate group, was grown by the Czochralski method. The parameters of the elementary unit cell of the crystal were measured by powder diffraction. The independent piezoelectric strain coefficients d{}_{11} and d_{14} were determined by the triple-axis X-ray diffraction in the Bragg and Laue geometries. Excitation and propagation of surface acoustic waves (SAW) were studied by high-resolution X-ray diffraction at BESSY II synchrotron radiation source. The velocity of SAW propagation and power flow angles in the Y-, X- and yxl/{+}36°-cuts of the CNGS crystal were determined from the analysis of the diffraction spectra. The CNGS crystal was found practically isotropic by its acoustic properties.

  9. Analytic studies of dispersive properties of shear Alfvén and acoustic wave spectra in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Chavdarovski, Ilija [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Zonca, Fulvio [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Associazione Euratom-ENEA sulla Fusione, C.R. Frascati, C.P. 65-00044 Frascati (Italy)

    2014-05-15

    The properties of the low frequency shear Alfvén and acoustic wave spectra in toroidal geometry are examined analytically and numerically considering wave particle interactions with magnetically trapped and circulating particles, using the theoretical model described in [I. Chavdarovski and F. Zonca, Plasma Phys. Controlled Fusion 51, 115001 (2009)] and following the framework of the generalized fishbone-like dispersion relation. Effects of trapped particles as well as diamagnetic effects on the frequencies and damping rates of the beta-induced Alfvén eigenmodes, kinetic ballooning modes and beta-induced Alfvén-acoustic eigenmodes are discussed and shown to be crucial to give a proper assessment of mode structure and stability conditions. Present results also demonstrate the mutual coupling of these various branches and suggest that frequency as well as mode polarization are crucial for their identification on the basis of experimental evidence.

  10. Thermal Properties of Materials Characterized by Scanning Electron-Acoustic Microscopy

    Institute of Scientific and Technical Information of China (English)

    GAO Chun-Ming; ZHANG Shu-Yi; ZHANG Zhong-Ning; SHUI Xiu-Ji; JIANG Tao

    2005-01-01

    @@ A modified technique of scanning electron-acoustic microscopy is employed to determine thermal diffusivity of materials. Using the dependence of the electron-acoustic signal on modulation frequency of the electron beam,the thermal diffusivity of materials is characterized based on a simplified thermoelastic theory. The thermal diffusivities of several metals characterized by the modified scanning electron-acoustic microscopy are in good agreement with the referential values of the corresponding materials, which proves that the scanning electronacoustic microscopy can be used to characterize the thermal diffusivity of materials effectively. In addition, for micro-inhomogeneous materials, such as biological tissues, the macro-effective (average) thermal diffusivities are characterized by the technique.

  11. Energy Properties of Ion Acoustic Waves in Stable and Unstable Plasmas

    DEFF Research Database (Denmark)

    Jensen, Vagn Orla; Lynov, Jens-Peter

    1979-01-01

    acoustic waves that are growing or damped in space the time average of the sum of the potential and the kinetic energy density is independent of position. Energy absorption spectra in particle velocity space are calculated; they are relatively broad and complicated functions. This shows that plasma ions......Energy exchange between potential energy and ion kinetic energy in an ion acoustic wave is considered. In order to investigate the linear Landau damping or growth, the energy is calculated by use of first‐order quantities only so that nonlinear effects are not involved. It is found that for ion...

  12. 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

  13. Acoustic properties of sintered FeCrAlY foams with open cells (Ⅰ): Static flow resistance

    Institute of Scientific and Technical Information of China (English)

    LU TianJian; M.KEPETS; A.P.DOWLING

    2008-01-01

    Open celled metal foams fabricated through the route of metal sintering are a new class of material that offers novel mechanical and acoustic properties. The metal sintering approach offers a cost-effective means for the mass-production of open-cell foams from a range of materials, including high-temperature steel alloys. The mechanical properties of open-celled steel alloy (FeCrAIY) foams have been characterized in previous studies, with focus placed on the influence of processing defects on stiffness and strength. In this work, the low-Reynolds number fluid properties of FeCrAIY foams were investigated both theoretically and experimen-tally. Specifically, the static flow resistance of the sintered foams important for heat transfer, filtration and sound absorption was modeled based on a cylinder and a sphere arranged in a periodic lattice at general incidence to the flow. Experimental measurements were subsequently carried out to validate theoretical predictions, with good agreement achieved.

  14. A study of the mechanical properties of highly porous ceramics using acoustic emission

    NARCIS (Netherlands)

    Aué, J.; Hosson, J.Th.M. De

    1998-01-01

    In this paper the results of indirect tensile tests on highly porous ceramics are presented. A relation between the mechanical strength of the highly porous ceramic materials and Acoustic Emission (AE) has been established. We have shown that the amplitude distribution of the AE events depends on th

  15. Acoustic radiation force impulse (ARFI) imaging: Characterizing the mechanical properties of tissues using their transient response to localized force

    Science.gov (United States)

    Nightingale, Kathryn R.; Palmeri, Mark L.; Congdon, Amy N.; Frinkely, Kristin D.; Trahey, Gregg E.

    2004-05-01

    Acoustic radiation force impulse (ARFI) imaging utilizes brief, high energy, focused acoustic pulses to generate radiation force in tissue, and conventional diagnostic ultrasound methods to detect the resulting tissue displacements in order to image the relative mechanical properties of tissue. The magnitude and spatial extent of the applied force is dependent upon the transmit beam parameters and the tissue attenuation. Forcing volumes are on the order of 5 mm3, pulse durations are less than 1 ms, and tissue displacements are typically several microns. Images of tissue displacement reflect local tissue stiffness, with softer tissues (e.g., fat) displacing farther than stiffer tissues (e.g., muscle). Parametric images of maximum displacement, time to peak displacement, and recovery time provide information about tissue material properties and structure. In both in vivo and ex vivo data, structures shown in matched B-mode images are in good agreement with those shown in ARFI images, with comparable resolution. Potential clinical applications under investigation include soft tissue lesion characterization, assessment of focal atherosclerosis, and imaging of thermal lesion formation during tissue ablation procedures. Results from ongoing studies will be presented. [Work supported by NIH Grant R01 EB002132-03, and the Whitaker Foundation. System support from Siemens Medical Solutions USA, Inc.

  16. Determination of near-surface material properties by line-focus acoustic microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Achenbach, J.D.; Li, W. [Northwestern Univ., Evanston, IL (United States)

    1996-12-31

    A line-focus acoustic microscope is used in conjunction with a multiple wave-mode method to determine elastic constants from a single V(z) measurement. V(z) curves which include contributions from different wave modes, measured using the line-focus acoustic microscope at 225 MHz, have been compared with theoretical results predicted by a V(z) measurement model. The determination of elastic constants has been achieved numerically by seeking a set of elastic constants that leads to the best fit, in the least square sense, of the theoretical results to the experimental ones. The method has been applied to isotropic materials in bulk, and plate and thin-film configurations. Elastic constants for each of these cases have been determined. The consistency, convergence, sensitivity and accuracy of the procedure have been investigated.

  17. Method based on broadband compressed pulse superposition to measure properties of underwater acoustic materials

    Institute of Scientific and Technical Information of China (English)

    LI Shui; MIAO Rongxing

    2001-01-01

    A method is proposed for the measurements of the performances of underwater acoustic finite sized large area material samples in a free field by using broadband pulse compression technique. As the result of which, the low-frequency cutoff of the standard tests is obviously reduced, and the broadband measurements are also realized. The experimental system provides measurements of complex reflection and transmission coefficients at continuous frequency points. From the data one can obtain the following acoustic parameters: echo reduction and insertion loss, absorption and attenuation coefficients, etc. The measurements are performed for two actual panels with the size 1 m×1 m in the frequency range from 2-20 kHz.

  18. Acoustic properties in the low and middle atmospheres of Mars and Venus.

    Science.gov (United States)

    Petculescu, Andi

    2016-08-01

    Generic predictions for acoustic dispersion and absorption in the atmospheres of Mars and Venus are presented. For Mars, Pathfinder and Mars Express ambient data and averaged thermophysical parameters are used as inputs to a preliminary model based on the continuum approximation for Mars' thin atmosphere-the need for Boltzmann-based treatment is discussed in the context of Knudsen numbers. Strong absorption constrains acoustic sensing within the Martian planetary boundary layer. For the dense atmosphere of Venus, the van der Waals equation of state is used. The thermophysical and transport parameters were interpolated at the ambient conditions. Acoustic sensing is discussed at 50 km above Venus' surface, a level where aerostats (e.g., European Space Agency's EVE) and manned airships (e.g., NASA's HAVOC) may be deployed in the future. The salient atmospheric characteristics are described in terms of temperature, pressure, and convective stability profiles, followed by wavenumber predictions, and discussions of low- and high-frequency sensing applications. At low frequencies, emphasis is placed on infrasound. A simple generation mechanism by Martian dust devils is presented, yielding fundamental frequencies between 0.1 and 10 Hz. High-frequency sensing is exemplified by ultrasonic anemometry. Of the two environments, Venus is notably more dispersive in the ultrasonic range.

  19. Acoustic properties of vowel production in prelingually deafened Mandarin-speaking children with cochlear implants.

    Science.gov (United States)

    Yang, Jing; Brown, Emily; Fox, Robert A; Xu, Li

    2015-11-01

    The present study examined the acoustic features of vowel production in Mandarin-speaking children with cochlear implants (CIs). The subjects included 14 native Mandarin-speaking, prelingually deafened children with CIs (2.9-8.3 yr old) and 60 age-matched, normal-hearing (NH) children (3.1-9.0 years old). Each subject produced a list of monosyllables containing seven Mandarin vowels: [i, a, u, y, ɤ, ʅ, ɿ]. Midpoint F1 and F2 of each vowel token were extracted and normalized to eliminate the effects of different vocal tract sizes. Results showed that the CI children produced significantly longer vowels and less compact vowel categories than the NH children did. The CI children's acoustic vowel space was reduced due to a retracted production of the vowel [i]. The vowel space area showed a strong negative correlation with age at implantation (r = -0.80). The analysis of acoustic distance showed that the CI children produced corner vowels [a, u] similarly to the NH children, but other vowels (e.g., [ʅ, ɿ]) differently from the NH children, which suggests that CI children generally follow a similar developmental path of vowel acquisition as NH children. These findings highlight the importance of early implantation and have implications in clinical aural habilitation in young children with CIs.

  20. Estimation of liquid properties by inverse problem analysis based on shear horizontal surface acoustic wave sensor responses

    Science.gov (United States)

    Ueda, Kento; Kondoh, Jun

    2017-07-01

    A shear horizontal surface acoustic wave (SH-SAW) sensor can detect liquid properties, such as viscosity, density, permittivity, and conductivity. The advantage of using the SH-SAW sensors is the simultaneous detection of the mechanical and electrical properties of liquids. In this paper, we proposed a method of estimating the density and viscosity of liquids based on the inverse problem analysis. Glycerol or ethanol aqueous solutions were measured. The estimated and literature values were compared. For glycerol aqueous solutions, when the concentration is low, those values agree well. However, when the concentration is high, those values did not agree because the bulk modulus of glycerin solutions cannot be assumed as constant. On the other hand, as the bulk modulus of ethanol aqueous solutions can be assumed to be the same as that of water, the deviations between those values were small. Therefore, the proposed method is effective when the bulk modulus is assumed as constant.

  1. Automated estimation of seabed properties from acoustic recordings by an autonomous moving system

    Science.gov (United States)

    Dosso, Stan; Dettmer, Jan; Holland, Charles; Mandolesi, Eric

    2016-04-01

    This work develops an automated Bayesian method to infer fluid seabed properties as a function of depth along tracks that are surveyed by an autonomous underwater vehicle (AUV). The AUV tows an acoustic source and a 32-element array. The source bandwidth is from 950 to 3000 Hz and frequency-modulated signals are emitted at regular intervals ('pings') as the AUV moves along the track. The recordings of each ping are processed to account for source directionality and reflection coefficients as a function of frequency and grazing angle are extracted by taking the ratio of time-windowed direct and bottom-interacted paths. Each ping provides one data set. This process results in large data volumes with an information content that is much higher than for traditional seismic profiling. However, extracting interpretable results about the lateral and vertical spatial variability of the seabed requires sophisticated and efficient inversion methods. The seabed is approximated as a horizontally stratified, lossy fluid for each ping. Each layer is homogeneous and parametrized by a thickness, velocity, density and attenuation. Since both source and array are towed close to the seabed, a plane-wave approximation is not sufficient to model these data and spherical reflection coefficients must be computed to predict data. Therefore, for each specular angle at each frequency, the Sommerfeld integral is solved efficiently by massively parallel implementation of Levin integration on a graphics processing unit (GPU). The inverse problem is strongly non-linear and requires application of Bayesian sampling to quantify parameter uncertainties. To account for the unknown number of layers in the seabed at each ping, the seabed is parametrized by a trans-dimensional (trans-D) model which treats the number of layers as unknown. To constrain model complexity and improve efficiency, we apply a Poisson prior with even-numbered order statistics to the number of layers. The trans-D model is

  2. Direct laboratory observation of fluid distribution and its influence on acoustic properties of patchy saturated rocks

    Science.gov (United States)

    Lebedev, M.; Clennell, B.; Pervukhina, M.; Shulakova, V.; Mueller, T.; Gurevich, B.

    2009-04-01

    Porous rocks in hydrocarbon reservoirs are often saturated with a mixture of two or more fluids. Interpretation of exploration seismograms requires understanding of the relationship between distribution of the fluids patches and acoustic properties of rocks. The sizes of patches as well as their distribution affect significantly the seismic response. If the size of the fluid patch is smaller than the diffusion wavelength then pressure equilibration is achieved and the bulk modulus of the rock saturated with a mixture is defined by the Gassmann equations (Gassmann, 1951) with the saturation-weighted average of the fluid bulk modulus given by Wood's law (Wood, 1955, Mavko et al., 1998). If the fluid patch size is much larger than the diffusion wavelength then there is no pressure communication between different patches. In this case, fluid-flow effects can be neglected and the overall rock may be considered equivalent to an elastic composite material consisting of homogeneous parts whose properties are given by Gassmann theory with Hill's equation for the bulk modulus (Hill, 1963, Mavko et al., 1998). At intermediate values of fluid saturation the velocity-saturation relationship is significantly affected by the fluid patch distribution. In order to get an improved understanding of factors influencing the patch distribution and the resulting seismic wave response we performed simultaneous measurements of P-wave velocities and rock sample CT imaging. The CT imaging allows us to map the fluid distribution inside rock sample during saturation (water imbibition). We compare the experimental results with theoretical predictions. In this paper we will present results of simultaneous measurements of longitudinal wave velocities and imaging mapping of fluid distribution inside rock sample during sample saturation. We will report results of two kinds of experiments: "dynamic" and "quasi static" saturation. In both experiments Casino Cores Otway Basin sandstone, Australia core

  3. The uncertainties calculation of acoustic method for measurement of dissipative properties of heterogeneous non-metallic materials

    Directory of Open Access Journals (Sweden)

    Мaryna O. Golofeyeva

    2015-12-01

    Full Text Available The effective use of heterogeneous non-metallic materials and structures needs measurement of reliable values of dissipation characteristics, as well as common factors of their change during the loading process. Aim: The aim of this study is to prepare the budget for measurement uncertainty of dissipative properties of composite materials. Materials and Methods: The method used to study the vibrational energy dissipation characteristics based on coupling of vibrations damping decrement and acoustic velocity in a non-metallic heterogeneous material is reviewed. The proposed method allows finding the dependence of damping on vibrations amplitude and frequency of strain-stress state of material. Results: Research of the accuracy of measurement method during the definition of decrement attenuation of fluctuations in synthegran was performed. The international approach for evaluation of measurements quality is used. It includes the common practice international rules for uncertainty expression and their summation. These rules are used as internationally acknowledged confidence measure to the measurement results, which includes testing. The uncertainties budgeting of acoustic method for measurement of dissipative properties of materials were compiled. Conclusions: It was defined that there are two groups of reasons resulting in errors during measurement of materials dissipative properties. The first group of errors contains of parameters changing of calibrated bump in tolerance limits, displacement of sensor in repeated placement to measurement point, layer thickness variation of contact agent because of irregular hold-down of resolvers to control surface, inaccuracy in reading and etc. The second group of errors is linked with density and Poisson’s ratio measurement errors, distance between sensors, time difference between signals of vibroacoustic sensors.

  4. Soft mode and acoustic mode ferroelectric properties of deuterated triglycine sulphate crystal

    Indian Academy of Sciences (India)

    Ashish Nautiyal; Trilok Chandra Upadhyay

    2014-02-01

    A mathematical study about deuterated triglycine sulphate (CD2CD2COOD)3D2SO4 crystal by a theoretical model which is extended with two sublattice pseudospin lattice coupled mode model by adding third, fourth and fifth order phonon anharmonic interaction terms as well as external electric field term in the crystal Hamiltonian. Double-time temperature dependent Green's function is used to derive soft mode frequency, dielectric permittivity, microwave absorption, quality factor, acoustic attenuation, electric conductivity, smooth function, relaxation time, ratio of figure of merits and respective applications in modern technologies. All theoretical results have a good agreement with experimental data.

  5. Prediction of acoustic foam properties by numerical simulation of polyurethane foaming process

    Directory of Open Access Journals (Sweden)

    Abdessalam Hichem

    2016-01-01

    Full Text Available This work aims to model and to simulate the polyurethane foaming process. Models taking into account the two main chemical reactions of the formation of polyurethane, the exothermic effect of these reactions as well as the thermo-rheo-kinetic coupling characterizing this process are proposed and implemented in the software NOGRID-points based on a meshless method (Finite Pointset Method. A prediction of some acoustic foam characteristics is also proposed based on the results of the numerical simulation of the foaming process and semi-phenomenological models.

  6. Experimental investigation on pore size effect on the linear viscoelastic properties of acoustic foams.

    Science.gov (United States)

    Deverge, Mickaël; Benyahia, Lazhar; Sahraoui, Sohbi

    2009-09-01

    This paper presents linear viscoelastic measurement on a large frequency range (10(-2)-10(8) Hz) for cross-linked polymer open-cell foams of same density and different pore sizes. This large extension of frequency range is obtained by the validation of a frequency-temperature superposition principle, commonly used with polymers. At higher frequencies, the shear moduli are independent of the pore size. In acoustical insulation range (1 Hz-16 kHz), the shear moduli decreases with the foams' pore size.

  7. Experimental investigation on pore size effect on the linear viscolelastic properties of acoustic foams

    OpenAIRE

    2009-01-01

    International audience; This paper presents linear viscoelastic measurement on a large frequency range (10(-2)- 10(8) Hz) for cross-linked polymer open-cell foams of same density and different pore sizes. This large extension of frequency range is obtained by the validation of a frequency-temperature superposition principle, commonly used with polymers. At higher frequencies, the shear moduli are independent of the pore size. In acoustical insulation range (1 Hz-16 kHz), the shear moduli decr...

  8. Acoustic properties of vowel production in prelingually deafened Mandarin-speaking children with cochlear implants

    OpenAIRE

    YANG, Jing; Brown, Emily; Fox, Robert A.; Xu, Li

    2015-01-01

    The present study examined the acoustic features of vowel production in Mandarin-speaking children with cochlear implants (CIs). The subjects included 14 native Mandarin-speaking, prelingually deafened children with CIs (2.9–8.3 yr old) and 60 age-matched, normal-hearing (NH) children (3.1–9.0 years old). Each subject produced a list of monosyllables containing seven Mandarin vowels: [i, a, u, y, ɤ, ʅ, ɿ]. Midpoint F1 and F2 of each vowel token were extracted and normalized to eliminate the e...

  9. The effect of vowel inventory and acoustic properties in Salento Italian learners of Southern British English vowels.

    Science.gov (United States)

    Escudero, Paola; Sisinni, Bianca; Grimaldi, Mirko

    2014-03-01

    Salento Italian (SI) listeners' categorization and discrimination of standard Southern British English (SSBE) vowels were examined in order to establish their initial state in the acquisition of the SSBE vowel system. The results of the vowel categorization task revealed that SI listeners showed single-category assimilation for many SSBE vowels and multiple-category assimilation for others. Additionally, SI vowel discrimination accuracy varied across contrasts, in line with the categorization results. This differential level of difficulty is discussed on the basis of current L2 perception models. The SI categorization results were then compared to the previously reported data on Peruvian Spanish (PS) listeners. Both SI and PS have a five-vowel inventory and therefore both listener groups were expected to have similar problems when distinguishing SSBE vowel contrasts, but were predicted to have different mappings of SSBE vowels to native categories due to the differences in the acoustic properties of vowels across the two languages. As predicted by the hypothesis that acoustic differences in production lead to a different nonnative perception, the comparison showed that there was large variability in how SSBE vowels are initially mapped to the specific five-vowel inventory. Predictions for differential L2 development across languages are also provided.

  10. The Acoustic Properties of Water Submerged Lodgepole Pine (Pinus contorta and Spruce (Picea spp. Wood and Their Suitability for Use as Musical Instruments

    Directory of Open Access Journals (Sweden)

    Calvin Hilde

    2014-08-01

    Full Text Available Wood is a common material used for the manufacture of many products, and submerged wood, in particular, has been used in niche markets and musical instruments. In order to examine if submerged wood in British Columbia, Canada, would be appropriate for use as musical instruments, a study was performed in 2007 on submerged wood from Ootsa Lake, British Columbia, Canada. The results of that study showed the wood was not suitable for musical instruments. In this paper, the wood samples were allowed to age untouched in a laboratory setting and were then retested under the hypothesis that physical acoustic characteristics would improve. It was shown, however, that acoustic properties became less adequate after being left to dry over time. This article describes the density, speed of sound, acoustic constant and characteristic impedance properties for submerged wood and a comparison is made for different applications for musical instruments.

  11. Experiments on the Flow Field and Acoustic Properties of a Mach number 0·75 Turbulent Air Jet at a Low Reynolds Number

    NARCIS (Netherlands)

    Slot, H.J.; Moore, P.; Delfos, R.; Boersma, B.J.

    2009-01-01

    In this paper we present the experimental results of a detailed investigation of the flow and acoustic properties of a turbulent jet with Mach number 0·75 and Reynolds number 3·5 103. We describe the methods and experimental procedures followed during the measurements, and subsequently present the f

  12. Study on the interfacial adhesion property of low-k thin film by the surface acoustic waves with cohesive zone model

    Science.gov (United States)

    Xiao, Xia; Qi, Haiyang; Tao, Ye; Kikkawa, Takamaro

    2016-12-01

    The cohesive zone model being increasingly used in discrete fracture processes simulation is adopted to study the interfacial adhesion property of low dielectric constant film deposited on the silicon substrate in this work. The two parameters, maximum normal traction and normal interface characteristic length in cohesive zone model, are taken into account to calculate the theoretical surface acoustic wave dispersion curves. Broadband surface acoustic wave signals with effective frequency up to 200 MHz are generated by short pulse ultraviolet laser source and detected by a piezoelectric transducer. The interfacial adhesion properties of dense and porous films determined accurately by matching the experimental dispersion curves with the calculated theoretical dispersion curves are 10.7 PPa/m and 2.8 PPa/m, respectively. The results show that the adhesion quality of dense low dielectric constant film is better than that of the porous. The study exhibits that the adhesion properties determined by improved laser-generated surface acoustic wave technique have the same trends with the test results of the nanoscratch technique, which indicates that the surface acoustic wave technique with cohesive zone model is a promising and nondestructive method for determining interfacial adhesion properties between low dielectric constant film and substrate.

  13. Measurement of Elastic Properties of Tissue by Shear Wave Propagation Generated by Acoustic Radiation Force

    Science.gov (United States)

    Tabaru, Marie; Azuma, Takashi; Hashiba, Kunio

    2010-07-01

    Acoustic radiation force (ARF) imaging has been developed as a novel elastography technology to diagnose hepatic disease and breast cancer. The accuracy of shear wave speed estimation, which is one of the applications of ARF elastography, is studied. The Young's moduli of pig liver and foie gras samples estimated from the shear wave speed were compared with those measured the static Young's modulus measurement. The difference in the two methods was 8%. Distance attenuation characteristics of the shear wave were also studied using finite element method (FEM) analysis. We found that the differences in the axial and lateral beam widths in pressure and ARF are 16 and 9% at F-number=0.9. We studied the relationship between two branch points in distance attenuation characteristics and the shape of ARF. We found that the maximum measurable length to estimate shear wave speed for one ARF excitation was 8 mm.

  14. Acoustic properties of sintered FeCrAlY foams with open cells (Ⅰ): Static flow resistance

    Institute of Scientific and Technical Information of China (English)

    M.; KEPETS; A.; P.; DOWLING

    2008-01-01

    Open celled metal foams fabricated through the route of metal sintering are a new class of material that offers novel mechanical and acoustic properties. The metal sintering approach offers a cost-effective means for the mass-production of open-cell foams from a range of materials, including high-temperature steel alloys. The mechanical properties of open-celled steel alloy (FeCrAlY) foams have been characterized in previous studies, with focus placed on the influence of processing defects on stiffness and strength. In this work, the low-Reynolds number fluid properties of FeCrAlY foams were investigated both theoretically and experimen- tally. Specifically, the static flow resistance of the sintered foams important for heat transfer, filtration and sound absorption was modeled based on a cylinder and a sphere arranged in a periodic lattice at general incidence to the flow. Experimental measurements were subsequently carried out to validate theoretical predictions, with good agreement achieved.

  15. 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...

  16. 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.

  17. Determination of Shear Properties in the Upper Seafloor Using Seismo-acoustic Interface Waves

    Energy Technology Data Exchange (ETDEWEB)

    Frivik, Svein Arne

    1998-12-31

    This thesis develops methods for recording and analysis of seismo-acoustic interface waves for determination of shear wave velocity as a function of depth and includes this in standard refraction seismic surveying. It investigates different techniques for estimation of dispersion characteristics of the interface waves and demonstrates that multi sensor spectral estimation techniques improve the dispersion estimates. The dispersion estimate of the fundamental interface wave mode is used as input to an object function for a model based linearized inversion. The inversion scheme provides an estimate of the shear wave velocity as a function of depth. Three field surveys were performed. Data were acquired with a standard bottom deployed refraction seismic hydrophone array containing 24 or 48 receivers, with a receiver spacing of 2.5 m. Explosive charges were used as sources. The recording time was increased from 0.5 to 8 s, compared to standard refraction seismic surveys. Shear wave velocity and shear modulus estimates were obtained from all the sites. At one of the sites, geotechnically obtained shear wave parameters were available, and a comparison between the two techniques were performed. the result of the comparison is promising and shows the potential of the technique. Although the result of applying the processing scheme to all three data sets is promising, it appears that survey parameters, like source-array spacing, receiver spacing and type of source might have been optimized for better performance. Based on this limitation, a new processing scheme and a new array configuration is proposed for surveys which integrates the recording and processing of both compressional waves and shear waves. 89 refs., 65 refs., 19 tabs.

  18. The correlation between acoustic and magnetic properties in the long working metal boiler drum with the parameters of the electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Ababkov, Nikolai, E-mail: n.ababkov@rambler.ru; Smirnov, Alexander, E-mail: galvas.kem@gmail.com [T.F. Gorbachev Kuzbass State Technical University, Vesennjaja str 28, Kemerovo, 650000 Russian Federation (Russian Federation)

    2016-01-15

    The present paper presents comparative analysis of measurement results of acoustic and magnetic properties in long working metal of boiler drums and the results obtained by methods of electronic microscopy. The structure of the metal sample from the fracture zone to the base metal (metal working sample long) and the center of the base metal before welding (weld metal sample) was investigated by electron microscopy. Studies performed by spectral acoustic, magnetic noise and electron microscopic methods were conducted on the same plots and the same samples of long working and weld metal of high-pressure boiler drums. The analysis of research results showed high sensitivity of spectral-acoustic and magnetic-noise methods to definition changes of microstructure parameters. Practical application of spectral-acoustic and magnetic noise NDT method is possible for the detection of irregularities and changes in structural and phase state of the long working and weld metal of boiler drums, made of a special molybdenum steel (such as 20M). The above technique can be used to evaluate the structure and physical-mechanical properties of the long working metal of boiler drums in the energy sector.

  19. Investigation of acoustic properties of a rigid foam with application to noise reduction in light aircraft

    Science.gov (United States)

    Holmer, C. I.

    1972-01-01

    A analytic model of sound transmission into an aircraft cabin was developed as well as test procedures which appropriately rank order properties which affect sound transmission. The proposed model agrees well with available data, and reveals that the pertinent properties of an aircraft cabin for sound transmission include: stiffness of cabin walls at low frequencies (as this reflects on impedance of the walls) and cabin wall transmission loss and interior absorption at mid and high frequencies. Below 315 Hz the foam contributes substantially to wall stiffness and sound transmission loss of typical light aircraft cabin construction, and could potentially reduce cabin noise levels by 3-5 db in this frequency range at a cost of about 0:2 lb/sq. ft. of treated cabin area. The foam was found not to have significant sound absorbing properties.

  20. Acoustic method of investigating the material properties and humidity sensing behavior of polymer coated piezoelectric substrates

    Science.gov (United States)

    Caliendo, Cinzia

    2006-09-01

    The relative humidity (RH) sensing behavior of a polymeric film was investigated by means of polymer coated surface acoustic wave (SAW) delay lines implemented on single crystal piezoelectric substrates, such as quartz and LiNbO3, and on thin piezoelectric polycrystalline films, such as ZnO and AlN, on Si and GaAs. The same SAW delay line configuration was implemented on each substrate and the obtained devices' operating frequency was in the range of 105-156MHz, depending on the type of the substrate, on its crystallographic orientation, and on the SAW propagation direction. The surface of each SAW device was covered by the same type RH sensitive film of the same thickness and the RH sensitivity of each polymer coated substrate, i.e., the SAW relative phase velocity shift per RH unit changes, was investigated in the 0%—80% RH range. The perturbational approach was used to relate the SAW sensor velocity response to the RH induced changes in the physical parameters of the sensitive polymer film: the incremental change in the mass density and shear modulus of the polymer film per unit RH change were estimated. The shift of the bare SAW delay lines operating frequency induced by the presence of the polymer film, at RH =0% and at T =-10°C, allowed the experimental estimation of the mass sensitivity values of each substrate. These values were in good accordance with those reported in the literature and with those theoretically evaluated by exact numerical calculation. The shift of the bare SAW delay lines propagation loss induced by the polymer coating of the device surface, at RH =0% and at ambient temperature, allowed the experimental estimation of the elastic sensitivity of each substrate. These values were found in good accordance with those available from the literature. The temperature coefficient of delay and the electromechanical coupling coefficient of the bare substrates were also estimated. The membrane sensitivity to ethanol, methanol and isopropylic

  1. System and method for generating micro-seismic events and characterizing properties of a medium with non-linear acoustic interactions

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-29

    A method and system includes generating a first coded acoustic signal including pulses each having a modulated signal at a central frequency; and a second coded acoustic signal each pulse of which includes a modulated signal a central frequency of which is a fraction d of the central frequency of the modulated signal for the corresponding pulse in the first plurality of pulses. A receiver detects a third signal generated by a non-linear mixing process in the mixing zone and the signal is processed to extract the third signal to obtain an emulated micro-seismic event signal occurring at the mixing zone; and to characterize properties of the medium or creating a 3D image of the properties of the medium, or both, based on the emulated micro-seismic event signal.

  2. Formation and properties of proton-exchanged and annealed $LiNbO_{3}$ waveguides for surface acoustic wave

    CERN Document Server

    Chien Chuan Cheng; Ying Chung Chen

    2001-01-01

    The proton-exchanged (PE) and annealed PE (APE) z-cut LiNbO/sub 3/ waveguides were fabricated using H/sub 4/P/sub 2/O/sub 7/. The positive strain, c-axis lattice constant change ( Delta c/c), was calculated to be about +0.43%, which was almost independent of the exchanged conditions. The penetration depth of H measured by secondary ion mass spectrometry (SIMS) exhibited a step-like profile, which was assumed to be equal to the waveguide depth (d). The surface acoustic wave (SAW) properties of PE and APE z-cut LiNbO/sub 3/ samples were investigated. The phase velocity (V/sub p/) and electromechanical coupling coefficient (K/sup 2/) of PE samples were significantly decreased by the increase of kd, where k was the wavenumber (2 pi / lambda ). The insertion loss (IL) of PE samples was increased by the increase of kd and became nearly constant at kd >0.064. The temperature coefficient of frequency (TCF) of PE samples allowed an apparent increase with kd, reaching a maximum at kd=0.292, then slightly decreased at h...

  3. Correlations between acoustic properties and bone density in bovine cancellous bone from 0.5 to 2 MHz

    Science.gov (United States)

    Lee, Kang Il; Roh, Heui-Seol; Yoon, Suk Wang

    2003-05-01

    Correlations between acoustic properties and bone density were investigated in the 12 defatted bovine cancellous bone specimens in vitro. Speed of sound (SOS) and broadband ultrasonic attenuation (BUA) were measured in three different frequency bandwidths from 0.5 to 2 MHz using three matched pairs of transducers with the center frequencies of 1, 2.25, and 3.5 MHz. The relative orientation between ultrasonic beam and bone specimen was the mediolateral (ML) direction of the bovine tibia. SOS shows significant linear positive correlation with apparent density for all three pairs of transducers. However, BUA shows relatively weak correlation with apparent density. SOS and BUA are only weakly correlated with each other. The linear combination of SOS and BUA in a multiple regression model leads to a significant improvement in predicting apparent density. The correlations among SOS, BUA, and bone density can be effectively and clearly represented in the three-dimensional space by the multiple regression model. These results suggest that the frequency range up to 1.5 MHz and the multiple regression model in the three-dimensional space can be useful in the osteoporosis diagnosis.

  4. Effect of Granule Sizes on Acoustic Properties of Protein-Based Silica Aerogel Composites via Novel Inferential Transmission Loss Method

    Directory of Open Access Journals (Sweden)

    Mahesh Sachithanadam

    2016-03-01

    Full Text Available The acoustic properties of the silica aerogel (SA granules of various sizes from 0.50 to 3.35 mm, distributed into six groups of nominal sizes and measured via a two-microphone impedance tube, are presented. The absorption coefficients of the SA granules were evaluated at ultra- to super-low frequency range from 50–1600 Hz. It was observed that nominal SA granules with sizes of 1.2 mm (AG2 and 1.7 mm (AG3 displayed the best absorption coefficients. When tested with granules filled at 5 cm depth, AG2 and AG3 absorption coefficients peaked at 980 Hz with values of 0.86 and 0.81, respectively. A novel approach to measure transmission loss (TL by using “inferential” principle is presented. This novel method, named “Inferential Transmission Loss Method” (InTLM, revealed that the average TL, TLavg for both AG2 and AG3 SA granules was 14.83 dB and 15.35 dB, respectively. Gelatin silica aerogels doped with sodium dodecyl sulfate (GSA–SDS composites comprising of 1.2 mm (GSA–AG2 and 1.7 mm (GSA–AG3 granules of various configurations were fabricated and evaluated for absorption coefficients and TL with known traditional acoustic panels. The results showed that GSA–AG3 had a better absorption coefficient over other configurations for the same corresponding thickness reaching the peak of 0.6 from 1300 to 1450 Hz with TLavg between 10.7 and 20.3 decibels. The four-layered GSA–AG2 and GSA–AG3 composites showed exceptionally high absorption from 500 to 800 Hz suitable for narrow band applications. Lastly, the “InTLM” was matched with the sound meter measurements, with high accuracy between 0.3 and 3.2 dB for low-frequency testing (50–1600 Hz.

  5. 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....

  6. Wave field characterization for non-destructive assessment of elastic properties using laser-acoustic sources in fluids and eye related tissues

    Science.gov (United States)

    Windisch, T.; Schubert, F.; Köhler, B.; Spörl, E.

    2010-03-01

    The age-related changes in the visco-elastic properties of the human lens are discussed with respect to presbyopia for a long time. All known measurement techniques are based on extracted lenses or are damaging the tissue. Hence, in vivo studies of lens hardness are not possible at the moment. To close this gap in lens diagnostics this project deals with an approach for a non-contact laser-acoustic characterization technique. Laser-generated wave fronts are reflected by the tissue interfaces and are also affected by the visco-elastic properties of the lens tissue. After propagating through the eye, these waves are recorded as corneal vibrations by laser vibrometry. A systematic analysis of amplitude and phase of these signals and the wave generation process shall give information about the interface locations and the tissues viscoelastic properties. Our recent studies on extracted porcine eyes proved that laser-acoustic sources can be systematically used for non-contacting generation and recording of ultrasound inside the human eye. Furthermore, a specific numerical model provides important contributions to the understanding of the complex wave propagation process. Measurements of the acoustic sources support this approach. Future investigations are scheduled to answer the question, whether this novel technique can be directly used during a laser surgery for monitoring purposes and if a purely diagnostic approach, e.g. by excitation in the aqueous humor, is also possible. In both cases, this technique offers a promising approach for non-contact ultrasound based eye diagnostics.

  7. Inulin and erythritol as sucrose replacers in short-dough cookies: sensory, fracture, and acoustic properties.

    Science.gov (United States)

    Laguna, Laura; Primo-Martín, Cristina; Salvador, Ana; Sanz, Teresa

    2013-05-01

    The effect of sucrose replacement by erythritol and inulin was studied in short-dough cookies using instrumental and sensory analysis. Two levels of replacement were used (25% and 50% of total sucrose content). Descriptive sensory analysis showed that the sucrose replacement affects visual and texture cookies characteristics, being the differences perceived by mouth greater than by hand. In general, sucrose substitutes produced a less crispy cookie and lower consumer acceptability, with the exception of 25% sucrose replacement by inulin. Matrix aeration attributes such as open and crumbly obtained by trained panel were important properties, and correlated positively with consumer acceptance and negatively with maximum force at break (hardness). Inulin cookies sensory properties were more similar to the control than the erythritol cookies. Also, consumer overall acceptance decreased significantly with sucrose replacement by erythritol. The analysis of texture and sound revealed that inulin cookies were softer whereas erythritol cookies were harder in comparison with control cookies; despite this difference, inulin cookies had similar sound characteristics to erythritol cookies.

  8. Acoustic Properties of the Voice Source and the Vocal Tract: Are They Perceptually Independent?

    Science.gov (United States)

    Erickson, Molly L

    2016-11-01

    This study sought to determine whether the properties of the voice source and vocal tract are perceptually independent. Within-subjects design. This study employed a paired-comparison paradigm where listeners heard synthetic voices and rated them as same or different using a visual analog scale. Stimuli were synthesized using three different source slopes and two different formant patterns (mezzo-soprano and soprano) on the vowel /a/ at four pitches: A3, C4, B4, and F5. Whereas formant pattern was the strongest effect, difference in source slope also affected perceived quality difference. Source slope and formant pattern were not independently perceived. These results suggest that when judging laryngeal adduction using perceptual information, judgments may not be accurate when the stimuli are of differing formant patterns. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  9. Predicting seabed properties from acoustic backscatter on the UK continental shelf (Invited)

    Science.gov (United States)

    McGonigle, C.; Collier, J.

    2010-12-01

    grain size distribution for the Clamshell grab was r2=0.120. Direct comparison of the Hamon and Clamshell grabs appears to suggest that the latter affords a better representation of true seabed properties because the former has a tendency to under sample the coarse fraction. The results of our study reinforce the idea that simple first order backscatter statistics can be used to predict seabed sediment properties. This is the most promising evidence of a relationship between these variables observed in the study area, and is comparable with the existing work. In this instance, the first order statistics from the multibeam backscatter imagery could be used to explain 63% of the variance observed in the Clamshell grab samples. Future work will determine whether more sophisticated methods such as angular-range (e.g. Fonseca and Mayer, 2007) can be used to improve the predictions of known sediment properties in this area. References Collier, J.S. and Brown, C. J. 2005. Correlation of sidescan backscatter with grain size distribution of surficial seabed sediments. Marine Geology, 214, 4, 431-449 Fonseca, L. and Mayer, L. 2007. Remote estimation of surficial seafloor properties through the application Angular Range Analysis to multibeam sonar data. Marine Geophysical Researches, 29, 2, 119-126

  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. 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. Characterization of material properties of soft solid thin layers with acoustic radiation force and wave propagation.

    Science.gov (United States)

    Urban, Matthew W; Nenadic, Ivan Z; Qiang, Bo; Bernal, Miguel; Chen, Shigao; Greenleaf, James F

    2015-10-01

    Evaluation of tissue engineering constructs is performed by a series of different tests. In many cases it is important to match the mechanical properties of these constructs to those of native tissues. However, many mechanical testing methods are destructive in nature which increases cost for evaluation because of the need for additional samples reserved for these assessments. A wave propagation method is proposed for characterizing the shear elasticity of thin layers bounded by a rigid substrate and fluid-loading, similar to the configuration for many tissue engineering applications. An analytic wave propagation model was derived for this configuration and compared against finite element model simulations and numerical solutions from the software package Disperse. The results from the different models found very good agreement. Experiments were performed in tissue-mimicking gelatin phantoms with thicknesses of 1 and 4 mm and found that the wave propagation method could resolve the shear modulus with very good accuracy, no more than 4.10% error. This method could be used in tissue engineering applications to monitor tissue engineering construct maturation with a nondestructive wave propagation method to evaluate the shear modulus of a material.

  13. Correlation between propagation loss and silicon dioxide film properties for surface acoustic wave devices.

    Science.gov (United States)

    Matsuda, Satoru; Miura, Michio; Matsuda, Takashi; Ueda, Masanori; Satoh, Yoshio; Hashimoto, Ken-Ya

    2013-05-01

    The correlation between the propagation loss and SiO2 film properties has been studied for temperature-compensated SAW devices using the SiO2/LiNbO3 structure. The SAW devices were prepared under different deposition temperatures for SiO2 film. Although they possessed excellent temperature coefficient of elasticity characteristics, devices prepared at lower temperature showed lower Q-factors. The SiO2 films were also deposited on a Si substrate under the same deposition conditions used for the SAW device preparation. Optical characterization was performed with Fourier transform infrared spectroscopy (FT-IR), spectrometer measurement, and Raman spectroscopy. IR absorbance spectra were almost same in the FT-IR measurement. However, optical attenuation in the UV region decreased with the deposition temperature in the spectrometer measurement. The optical attenuation is caused by the increase of the extinction coefficient in the SiO2 layer, and its optical wavelength dependence indicated that observed excess attenuation is caused by Rayleigh scattering. The Raman scattering also decreased with the deposition temperature in the Raman spectroscopy. The scattering is caused by the distortion of the SiO2 network. These results indicate that the Rayleigh scattering caused by the distortion of the SiO2 network is the main contributor to the excess SAW propagation loss in this case.

  14. Relationships among chemical composition, lattice constants, and acoustic properties for Ca3Ta(Ga1-xAlx)3Si2O14 single crystals

    Science.gov (United States)

    Ohashi, Yuji; Kitahara, Masanori; Kudo, Tetsuo; Arakawa, Mototaka; Yokota, Yuui; Shoji, Yasuhiro; Yamaji, Akihiro; Kurosawa, Shunsuke; Kamada, Kei; Yoshikawa, Akira

    2017-06-01

    The relationship among lattice constant a, Al content, and acoustic properties were experimentally examined using a plate specimen perpendicular to Y-axis prepared from Ca3Ta(Ga0.75Al0.25)3Si2O14 [CTGAS(0.25)] single crystal grown by Czochralski method. As the acoustic properties, leaky surface acoustic wave (LSAW) velocities with different propagation directions, X- and Z-propagations, and longitudinal wave velocity propagating along Y-axis direction were measured by the line-focus-beam/plane-wave ultrasonic-material-characterization (LFB/PW-UMC) system. The measured results of LSAW velocity distributions revealed inhomogeneity in radial direction of the crystal ingot exhibiting lower velocity area at the center of the ingot. In addition, the distributions of lattice constant a and chemical composition (especially Al content) were measured along the radial direction. Abnormal changes suggesting existence of residual stresses concentrated on the central part of the crystal ingot other than the effect of chemical composition change were detected from the relationships among the measured parameters.

  15. Piezoelectric Ca{sub 3}NbGa{sub 3}Si{sub 2}O{sub 14} crystal: crystal growth, piezoelectric and acoustic properties

    Energy Technology Data Exchange (ETDEWEB)

    Roshchupkin, Dmitry; Emelin, Evgenii [Russian Academy of Sciences, Institute of Microelectronics Technology and High-Purity Materials, Chernogolovka, Moscow District (Russian Federation); National University of Science and Technology MISiS, Moscow (Russian Federation); Ortega, Luc [Univ. Paris-Sud, CNRS, UMR 8502, Laboratoire de Physique des Solides, Orsay Cedex (France); Plotitcyna, Olga; Irzhak, Dmitry [Russian Academy of Sciences, Institute of Microelectronics Technology and High-Purity Materials, Chernogolovka, Moscow District (Russian Federation); Erko, Alexei; Zizak, Ivo; Vadilonga, Simone [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Institute for Nanometre Optics and Technology, Berlin (Germany); Buzanov, Oleg [FOMOS Materials Co., Moscow (Russian Federation); Leitenberger, Wolfram [Universitaet Potsdam Institut fuer Physik, Potsdam (Germany)

    2016-08-15

    Ca{sub 3}NbGa{sub 3}Si{sub 2}O{sub 14} (CNGS), a five-component crystal of lanthanum-gallium silicate group, was grown by the Czochralski method. The parameters of the elementary unit cell of the crystal were measured by powder diffraction. The independent piezoelectric strain coefficients d{sub 11} and d{sub 14} were determined by the triple-axis X-ray diffraction in the Bragg and Laue geometries. Excitation and propagation of surface acoustic waves (SAW) were studied by high-resolution X-ray diffraction at BESSY II synchrotron radiation source. The velocity of SAW propagation and power flow angles in the Y-, X- and yxl/+36 {sup circle} -cuts of the CNGS crystal were determined from the analysis of the diffraction spectra. The CNGS crystal was found practically isotropic by its acoustic properties. (orig.)

  16. Geomechanical and anisotropic acoustic properties of Lower Jurassic Posidonia shales from Whitby (UK)

    Science.gov (United States)

    Zhubayev, Alimzhan; Houben, Maartje; Smeulders, David; Barnhoorn, Auke

    2014-05-01

    The Posidonia Shale Formation (PSF) is one of the possible resource shales for unconventional gas in Northern Europe and currently is of great interest to hydrocarbon exploration and production. Due to low permeability of shales, economically viable production requires hydraulic fracturing of the reservoir. The design of hydrofractures requires an estimate of stress state within the reservoir and geomechanical properties such as Young's modulus and Poisson's ratio. Shales are often highly anisotropic and the models which neglect shale anisotropy may fail to predict the behaviour of hydrofractures. Seismic attenuation anisotropy, on the other hand, can play a key role in quantitative rock characterization. Where the attenuation anisotropy can potentially be linked to anisotropic permeability of shales, its fluid/gas saturation and preferred development of anisotropic fracture orientations. In this research, by utilizing the so-called Thomsen's notations, the elastic anisotropy of our (fractured and unfractured) shales has been investigated using a pulse transmission technique in the ultrasonic frequency range (0.3-1 MHz). Assuming transverse isotropy of the shales, and taking the axis x3 as the axis of rotational symmetry, directional Young's moduli and Poisson's ratios were obtained. The Young's modulus measured parallel to bedding (E1) is found to be larger than the Young's modulus measured orthogonal to bedding (E3). In case of the Poisson's ratios, we found that ν31 is larger than ν12, where νijrelates elastic strain in xj direction to stress applied in xi direction. Finally, attenuation anisotropy in dry and layer-parallel fractured Posidonia shale samples has been studied in the same frequency range. The attenuation of compressional (QP-1) and shear (QS-1) waves increases substantially with a macro (or wavelength) fracture introduction, especially for P and S waves propagating orthogonal to the bedding. In non-fractured and fractured dry shales, QP-1 is

  17. 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...

  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. 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

  20. 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.

  1. The Acoustic Properties of Low Intensity Vocalizations Match Hearing Sensitivity in the Webbed-Toed Gecko, Gekko subpalmatus

    Science.gov (United States)

    Chen, Jingfeng; Jono, Teppei; Cui, Jianguo; Yue, Xizi; Tang, Yezhong

    2016-01-01

    The design of acoustic signals and hearing sensitivity in socially communicating species would normally be expected to closely match in order to minimize signal degradation and attenuation during signal propagation. Nevertheless, other factors such as sensory biases as well as morphological and physiological constraints may affect strict correspondence between signal features and hearing sensitivity. Thus study of the relationships between sender and receiver characteristics in species utilizing acoustic communication can provide information about how acoustic communication systems evolve. The genus Gekko includes species emitting high-amplitude vocalizations for long-range communication (loud callers) as well as species producing only low-amplitude vocalizations when in close contact with conspecifics (quiet callers) which have rarely been investigated. In order to investigate relationships between auditory physiology and the frequency characteristics of acoustic signals in a quiet caller, Gekko subpalmatus we measured the subjects’ vocal signal characteristics as well as auditory brainstem responses (ABRs) to assess auditory sensitivity. The results show that G. subpalmatus males emit low amplitude calls when encountering females, ranging in dominant frequency from 2.47 to 4.17 kHz with an average at 3.35 kHz. The auditory range with highest sensitivity closely matches the dominant frequency of the vocalizations. This correspondence is consistent with the notion that quiet and loud calling species are under similar selection pressures for matching auditory sensitivity with spectral characteristics of vocalizations. PMID:26752301

  2. 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.

  3. 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...

  4. 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...

  5. Woods with physical, mechanical and acoustic properties similar to those of Caesalpinia echinata have high potential as alternative woods for bow makers

    Directory of Open Access Journals (Sweden)

    Eduardo Luiz Longui

    2014-09-01

    Full Text Available For nearly two hundred years, Caesalpinia echinata wood has been the standard for modern bows. However, the threat of extinction and the enforcement of trade bans have required bow makers to seek alternative woods. The hypothesis tested was that woods with physical, mechanical and acoustic properties similar to those of C. echinata would have high potential as alternative woods for bows. Accordingly, were investigated Handroanthus spp., Mezilaurus itauba, Hymenaea spp., Dipteryx spp., Diplotropis spp. and Astronium lecointei. Handroanthus and Diplotropis have the greatest number of similarities with C. echinata, but only Handroanthus spp. showed significant results in actual bow manufacture, suggesting the importance of such key properties as specific gravity, speed of sound propagation and modulus of elasticity. In practice, Handroanthus and Dipteryx produced bows of quality similar to that of C. echinata.

  6. Properties of high sensitivity ZnO surface acoustic wave sensors on SiO 2/(1 0 0) Si substrates

    Science.gov (United States)

    Krishnamoorthy, Soumya; Iliadis, Agis A.

    2008-11-01

    The properties of ZnO/SiO2/Si surface acoustic wave (SAW) Love mode sensors were examined and optimized to achieve high mass sensitivity. SAW devices A and B, were designed and fabricated to operate at resonant frequencies around 0.7 and 1.5 GHz. The ZnO films grown by pulsed laser deposition on SiO2/Si demonstrated c-axis growth and the fabricated devices showed guided shear horizontal surface acoustic wave (or Love mode) propagation. Acoustic phase velocity in the ZnO layer was measured in both devices A and B and theoretical and experimental evaluation of the mass sensitivity showed that the maximum sensitivity is obtained for devices with ZnO guiding layer thicknesses of 340 nm and 160 nm for devices A and B, respectively. The performance of the SAW sensors was validated by measuring the mass of a well-characterized polystyrene-polyacrylic acid diblock copolymer film. For the optimized sensors, maximum mass sensitivity values were as high as 4.309 μm2/pg for device A operating at 0.7477 GHz, and 8.643 μm2/pg for device B operating at 1.5860 GHz. The sensors demonstrated large frequency shifts per applied mass (0.1-4 MHz), excellent linearity, and extended range in the femto-gram region. The large frequency shifts indicated that these sensors have the potential to measure mass two to three orders of magnitude lower in the atto-gram range.

  7. 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...

  8. Influence of thermodynamic properties of a thermo-acoustic emitter on the efficiency of thermal airborne ultrasound generation.

    Science.gov (United States)

    Daschewski, M; Kreutzbruck, M; Prager, J

    2015-12-01

    In this work we experimentally verify the theoretical prediction of the recently published Energy Density Fluctuation Model (EDF-model) of thermo-acoustic sound generation. Particularly, we investigate experimentally the influence of thermal inertia of an electrically conductive film on the efficiency of thermal airborne ultrasound generation predicted by the EDF-model. Unlike widely used theories, the EDF-model predicts that the thermal inertia of the electrically conductive film is a frequency-dependent parameter. Its influence grows non-linearly with the increase of excitation frequency and reduces the efficiency of the ultrasound generation. Thus, this parameter is the major limiting factor for the efficient thermal airborne ultrasound generation in the MHz-range. To verify this theoretical prediction experimentally, five thermo-acoustic emitter samples consisting of Indium-Tin-Oxide (ITO) coatings of different thicknesses (from 65 nm to 1.44 μm) on quartz glass substrates were tested for airborne ultrasound generation in a frequency range from 10 kHz to 800 kHz. For the measurement of thermally generated sound pressures a laser Doppler vibrometer combined with a 12 μm thin polyethylene foil was used as the sound pressure detector. All tested thermo-acoustic emitter samples showed a resonance-free frequency response in the entire tested frequency range. The thermal inertia of the heat producing film acts as a low-pass filter and reduces the generated sound pressure with the increasing excitation frequency and the ITO film thickness. The difference of generated sound pressure levels for samples with 65 nm and 1.44 μm thickness is in the order of about 6 dB at 50 kHz and of about 12 dB at 500 kHz. A comparison of sound pressure levels measured experimentally and those predicted by the EDF-model shows for all tested emitter samples a relative error of less than ±6%. Thus, experimental results confirm the prediction of the EDF-model and show that the model can

  9. 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....

  10. 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...

  11. 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...

  12. 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.

  13. Advanced piezoelectric crystal Ca{sub 3}TaGa{sub 3}Si{sub 2}O{sub 14}: growth, crystal structure perfection, and acoustic properties

    Energy Technology Data Exchange (ETDEWEB)

    Roshchupkin, Dmitry; Plotitcyna, Olga; Irzhak, Dmitry; Fahrtdinov, Rashid [Russian Academy of Sciences, Institute of Microelectronics Technology and High-Purity Materials, Chernogolovka, Moscow District (Russian Federation); Ortega, Luc [Universite Paris-Sud, CNRS, UMR 8502, Laboratoire de Physique des Solides, Orsay Cedex (France); Erko, Alexei; Zizak, Ivo [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Institute for Nanometre Optics and Technology, Berlin (Germany); Buzanov, Oleg [FOMOS Materials Co., Moscow (Russian Federation)

    2014-03-15

    A five-component crystal of the lanthanum-gallium silicate family Ca{sub 3}TaGa{sub 3}Si{sub 2}O{sub 14} (CTGS) was grown by the Czochralski method. The CTGS crystal, like the langasite crystal (La{sub 3}Ga{sub 5}SiO{sub 14}, LGS), possesses unique temperature properties and the fewer number of the Ga atoms in the unit cell makes the density much lower and, consequently, increases the velocity of acoustic wave propagation. The unit-cell parameters were determined by the powder diffraction technique. The defects in the CTGS crystal structure were studied by X-ray topography, which enables the visualization of growth banding characteristics of crystals grown by the Czochralski method. Surface acoustic wave (SAW) propagation in the CTGS crystal was investigated by the high-resolution X-ray diffraction method on the BESSY II synchrotron radiation source. The velocities of propagation and power flow angles of SAWs in the Y- and X-cuts of the CTGS crystal were determined from the X-ray diffraction spectra. (orig.)

  14. In vivo feasibility case study for evaluating abdominal aortic aneurysm tissue properties and rupture potential using acoustic radiation force impulse imaging.

    Science.gov (United States)

    Tierney, Aine P; Callanan, Anthony; McGloughlin, Timothy M

    2011-04-01

    An abdominal aortic aneurysm (AAA) is defined as a permanent and irreversible localized dilatation of the abdominal aorta. A reliable, non-invasive method to assess the wall mechanics of an aneurysm may provide additional information regarding their susceptibility to rupture. Acoustic radiation force impulse (ARFI) imaging is a phenomenon associated with the propagation of acoustic waves in attenuating media. This study was a preliminary evaluation to explore the feasibility of using ARFI imaging to examine an AAA in vivo. A previously diagnosed in vivo aneurysm case study was imaged to demonstrate the viability of excitation of the abdominal aorta using ARFI imaging. Ex vivo experiments were used to assess an artificially induced aneurysm to establish its development and whether ARFI was able to capture the mechanical changes during artificial aneurysm formation. A combination of in vivo and ex vivo results demonstrated a proposed hypothesis of estimation of the tissue's stiffness properties. The study details a method for non-invasive rupture potential prediction of AAAs using patient-specific moduli to generate a physiological stiffness rupture potential index (PSRPI) of the AAA. Clinical feasibility of ARFI imaging as an additional surgical tool to interrogate AAAs was verified and methods to utilize this data as a diagnostic tool was demonstrated with the PSRPI.

  15. Effect of Al–5Ti–1B grain refiner on the microstructure, mechanical properties and acoustic emission characteristics of Al5052 aluminium alloy

    Directory of Open Access Journals (Sweden)

    Amulya Bihari Pattnaik

    2015-04-01

    Full Text Available In the present investigation, the effect of Al–5Ti–1B grain refiner on the microstructure, mechanical properties and acoustic emission characteristics of Al 5052 aluminium alloy have been studied. Microstructural analysis showed the presence of primary α solid solution. No Al–Mg phase was found to be formed due to the presence of magnesium in the solid solution. The results indicated that the addition of Al–5Ti–1B grain refiner into the alloy caused a significant improvement in ultimate tensile strength (UTS and elongation values from 114 MPa and 7.8% to 185 MPa and 18% respectively. The main mechanisms behind this improvement were found to be due to the grain refinement during solidification and segregation of Ti at primary α grain boundaries. Acoustic emission (AE results indicated that intensity of AE signals increased with increase in Al–5Ti–1B master alloy content, which had been attributed to the combined effect of dislocation motion and grain refinement. The field emission scanning electron microscopy (FESEM and energy dispersive X-ray (EDX analysis were used to study the microstructure and fracture surfaces of the samples.

  16. 粘弹性材料声阻抗非局域特性的数值研究%Study of the numerical simulation of a non-local property of acoustic impedance in viscoelastic material

    Institute of Scientific and Technical Information of China (English)

    杨明绥; 王同庆; 范真真

    2011-01-01

    A model of the acoustic impedance matrix was proposed to describe the local and non-local properties of acoustic scattering. The derivation of an acoustic impedance matrix and its algebraic model were completed. On the basis of the viscoelastic finite element method a numerical calculation code was programmed. The code validation and its calculation precision were proven. Finally, an acoustic impedance matrix was computed for a viscoelastic plate backed by a rigid body, and its parameters from an algebraic model were fitted. The local and non-local properties of acoustic impedance and the variation of parameters in the model were analyzed in detail. The results of the experiment show that the non-local properties of viscoelastic material surface acoustic scattering impedance can be described, both qualitatively and quantitatively by the acoustic impedance matrix and non-local acoustic impedance algebraic model. Therefore, an effective numerical calculation method was proposed to research the non-local properties of acoustic impedance.%针对刚性背衬下的粘弹性材料层,提出了一种能够描述表面声散射的局域/非局域特性的声阻抗矩阵模型,进行了声阻抗矩阵及代数模型的推导.以粘弹性有限元为基础完成了数值计算工具的开发,并对自编代码进行了校核,表明数值工具具有较高的计算精度.计算了刚性背衬下粘弹性板的声阻抗矩阵,并拟合得到声阻抗模型参数,分析了声阻抗局域、非局域特性及代数模型中各参数的变化规律.实际计算结果表明:声阻抗矩阵和非局域声阻抗代数模型能够定性和定量描述粘弹性材料表面声散射阻抗的非局域特性,为声阻抗非局域特性的研究提供了一个有效的数值分析方法.

  17. 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.

  18. Magnetostriction and Acoustics Properties of Tb1-xDyx(Fe1-yMny)1.95 Alloys and Their Application to Sonar Transducers

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The magnetostriction and acoustics properties of Tb1-xDyx(Fe1-yMny)1.95 alloys and their application to sonar transducers were studied. The following results were obtained from experiments. When the applied magnetic field intensity is ≥800 kA.m-1, the magnetostrictive coefficients are (1300~1800)×10-6. The electromechanical coupling factors are 0.84~0.93, the sound velocities 2168~2856 m·s-1 and the Young′s modulus (5.06~7.26)×1010 N·m-2. A sonar transducer made of the alloy rod, which has a total length of 300 mm and a total weight of 2 kg, is characterized by 2.4 kHz specified resonant frequency, 1 kHz frequency band, 173 kB current response and 45% electroacoustic efficiency.

  19. Properties of cylindrical and spherical heavy ion-acoustic solitary and shock structures in a multispecies plasma with superthermal electrons

    Science.gov (United States)

    Shah, M. G.; Rahman, M. M.; Hossen, M. R.; Mamun, A. A.

    2016-02-01

    A theoretical investigation on heavy ion-acoustic (HIA) solitary and shock structures has been accomplished in an unmagnetized multispecies plasma consisting of inertialess kappa-distributed superthermal electrons, Boltzmann light ions, and adiabatic positively charged inertial heavy ions. Using the reductive perturbation technique, the nonplanar (cylindrical and spherical) Kortewg-de Vries (KdV) and Burgers equations have been derived. The solitary and shock wave solutions of the KdV and Burgers equations, respectively, have been numerically analyzed. The effects of superthermality of electrons, adiabaticity of heavy ions, and nonplanar geometry, which noticeably modify the basic features (viz. polarity, amplitude, phase speed, etc.) of small but finite amplitude HIA solitary and shock structures, have been carefully investigated. The HIA solitary and shock structures in nonplanar geometry have been found to distinctly differ from those in planar geometry. Novel features of our present attempt may contribute to the physics of nonlinear electrostatic perturbation in astrophysical and laboratory plasmas.

  20. System and method to create three-dimensional images of non-linear acoustic properties in a region remote from a borehole

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Cung; Nihei, Kurt T.; Schmitt, Denis P.; Skelt, Christopher; Johnson, Paul A.; Guyer, Robert; TenCate, James A.; Le Bas, Pierre-Yves

    2013-01-01

    In some aspects of the disclosure, a method for creating three-dimensional images of non-linear properties and the compressional to shear velocity ratio in a region remote from a borehole using a conveyed logging tool is disclosed. In some aspects, the method includes arranging a first source in the borehole and generating a steered beam of elastic energy at a first frequency; arranging a second source in the borehole and generating a steerable beam of elastic energy at a second frequency, such that the steerable beam at the first frequency and the steerable beam at the second frequency intercept at a location away from the borehole; receiving at the borehole by a sensor a third elastic wave, created by a three wave mixing process, with a frequency equal to a difference between the first and second frequencies and a direction of propagation towards the borehole; determining a location of a three wave mixing region based on the arrangement of the first and second sources and on properties of the third wave signal; and creating three-dimensional images of the non-linear properties using data recorded by repeating the generating, receiving and determining at a plurality of azimuths, inclinations and longitudinal locations within the borehole. The method is additionally used to generate three dimensional images of the ratio of compressional to shear acoustic velocity of the same volume surrounding the borehole.

  1. 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.

  2. Acoustic clouds: standing sound waves around a black hole analogue

    CERN Document Server

    Benone, Carolina L; Herdeiro, Carlos; Radu, Eugen

    2014-01-01

    Under certain conditions sound waves in fluids experience an acoustic horizon with analogue properties to those of a black hole event horizon. In particular, a draining bathtub-like model can give rise to a rotating acoustic horizon and hence a rotating black hole (acoustic) analogue. We show that sound waves, when enclosed in a cylindrical cavity, can form stationary waves around such rotating acoustic black holes. These acoustic perturbations display similar properties to the scalar clouds that have been studied around Kerr and Kerr-Newman black holes; thus they are dubbed acoustic clouds. We make the comparison between scalar clouds around Kerr black holes and acoustic clouds around the draining bathtub explicit by studying also the properties of scalar clouds around Kerr black holes enclosed in a cavity. Acoustic clouds suggest the possibility of testing, experimentally, the existence and properties of black hole clouds, using analog models.

  3. 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.

  4. 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.

  5. 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...

  6. 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...

  7. 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...

  8. Theoretical analysis of surface acoustic wave propagating properties of Y-cut nano lithium niobate film on silicon dioxide

    Directory of Open Access Journals (Sweden)

    Jing Chen

    2015-08-01

    Full Text Available The surface acoustic wave (SAW propagating characteristics of Y-cut nano LiNbO3 (LN film on SiO2/LN substrate have been theoretically calculated. The simulated results showed a shear horizontal (SH SAW with enhanced electromechanical coupling factor K2 owing to a dimensional effect of the nanoscale LN film. However, a Rayleigh SAW and two other resonances related to thickness vibrations caused spurious responses for wideband SAW devices. These spurious waves could be fully suppressed by properly controlling structural parameters including the electrode layer height, thickness, and the Euler angle (θ of the LN thin film. Finally, a pure SH SAW was obtained with a wide θ range, from 0° to 5° and 165° to 180°. The largest K2 achieved for the pure SH SAW was about 35.1%. The calculated results demonstrate the promising application of nano LN film to the realization of ultra-wideband SAW devices.

  9. EFFECT OF TOOL WEAR ON MICROSTRUCTURE, MECHANICAL PROPERTIES AND ACOUSTIC EMISSION OF FRICTION STIR WELDED 6061 Al ALLOY

    Institute of Scientific and Technical Information of China (English)

    W.M. Zeng; H.L. Wu; J. Zhang

    2006-01-01

    Tool condition is one of the main concerns in friction stir welding (FSW), because the geometrical condition of the tool pin including size and shape is strongly connected to the microstructure and mechanical performance of the weld. Tool wear occurs during FSW, especially for welding metal matrix composites with large amounts of abrasive particles, and high melting point materials, which significantly expedite tool wear and deteriorate the mechanical performance of welds.Tools with different pin-wear levels are used to weld 6061 Al alloy, while acoustic emission (AE) sensing, metallographic sectioning, and tensile testing are employed to evaluate the weld quality in various tool wear conditions. Structural characterization shows that the tool wear interferes with the weld quality and accounts for the formation of voids in the nugget zone. Tensile test analysis of samples verifies that both the ultimate tensile strength and the yield strength are adversely affected by the formation of voids in the nugget due to the tool wear. The failure location during tensile test clearly depends on the state of the tool wear, which led to the analysis of the relationships between the structure of the nugget and tool wear. AE signatures recorded during welding reveal that the AE hits concentrate on the higher amplitudes with increasing tool wear. The results show that the AE sensing provides a potentially effective method for the on-line monitoring of tool wear.

  10. 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.

  11. A high pulse repetition frequency ultrasound system for the ex vivo measurement of mechanical properties of crystalline lenses with laser-induced microbubbles interrogated by acoustic radiation force.

    Science.gov (United States)

    Yoon, Sangpil; Aglyamov, Salavat; Karpiouk, Andrei; Emelianov, Stanislav

    2012-08-07

    A high pulse repetition frequency ultrasound system for an ex vivo measurement of mechanical properties of an animal crystalline lens was developed and validated. We measured the bulk displacement of laser-induced microbubbles created at different positions within the lens using nanosecond laser pulses. An impulsive acoustic radiation force was applied to the microbubble, and spatio-temporal measurements of the microbubble displacement were assessed using a custom-made high pulse repetition frequency ultrasound system consisting of two 25 MHz focused ultrasound transducers. One of these transducers was used to emit a train of ultrasound pulses and another transducer was used to receive the ultrasound echoes reflected from the microbubble. The developed system was operating at 1 MHz pulse repetition frequency. Based on the measured motion of the microbubble, Young's moduli of surrounding tissue were reconstructed and the values were compared with those measured using the indentation test. Measured values of Young's moduli of four bovine lenses ranged from 2.6 ± 0.1 to 26 ± 1.4 kPa, and there was good agreement between the two methods. Therefore, our studies, utilizing the high pulse repetition frequency ultrasound system, suggest that the developed approach can be used to assess the mechanical properties of ex vivo crystalline lenses. Furthermore, the potential of the presented approach for in vivo measurements is discussed.

  12. EPU/EP 弹性体的力学及水声吸声性能%Mechanical properties and underwater acoustic absorption properties of epoxyurethane/epoxy elastomers

    Institute of Scientific and Technical Information of China (English)

    孙卫红; 刘波; 晏欣

    2014-01-01

    Epoxyurethane (EPU)was prepared using dibutyltin dilaurate (DBTDL)as a catalyst and glycidol as a capping agent.EPU and EPU /EP blend elastomers were prepared using butyl acrylate-diethylenetriamine (BA-DETA)as a curing agent with the casting method,the tensile properties,dynamic mechanical properties and underwater acoustic properties of these blend elastomers were characterized.The results showed that the tensile strength of EPU /EP blend elastomers increases with increase in amount of epoxy resin;the tensile strength of TDI-type epoxyurethanes are higher than that of IPDI-type epoxyurethane;with increase in content of EP,the middle and high temperature transition peaks and Young's modulus of TDI-type epoxyurethane /E-51 blends become larger,and the compatibility of the two components becomes worse;EPU1 /E-51 series blends have a good underwater acoustic absorption ability;the underwater acoustic absorption ability of EPU1 /E-51 (70 /30)elastomers is the best,its average acoustic absorption coefficient is 0.75,and its maximum acoustic absorption coefficient is 0.94.%以二丁基二月桂酸锡(DBTDL)作催化剂、环氧丙醇作封端剂制备了环氧氨酯(EPU);以自制的丙烯酸丁酯-二乙烯三胺(BA -DETA)为固化剂用浇铸法制备了 EPU 及环氧氨酯/环氧树脂(EPU /EP)共混物弹性体,并对该系列共混物弹性体的力学性能、动态力学性能和水声声学性能进行了表征,研究结果表明:随着 EP 用量的增加,EPU /EP 共混物的拉伸强度逐渐增大,TDI 型环氧氨酯的抗拉强度高于 IPDI 型环氧氨酯;随着 EP 含量的增加,TDI 型环氧氨酯/环氧-E51(EPU1/E -51)共混物中、高温转变峰增强,杨氏模量变大,两组分相容性变差;EPU1/E -51系列共混物具有良好的水声吸声性能。EPU1/E -51(70/30)弹性体的水声性能最优,其平均吸声系数为0.75,最大吸声系数为0.94。

  13. Acoustic excitation of diffusion flames with coherent structure in a plane shear layer.; Effects of acoustic excitation on combustion properties; Soshiki kozo wo tomonau sendan kakusan kaen no onkyo reiki.; Onkyo reiki ni yoru nensho tokusei no henka

    Energy Technology Data Exchange (ETDEWEB)

    Ishino, Y.; Kojima, T.; Oiwa, N.; Yamaguchi, S. [Nagoya Institute of Technology, Nagoya (Japan)

    1993-10-25

    This paper reports on experiments for acoustic excitation of plane shear structured flame. Flows of air separated into the higher velocity side and the lower velocity side by a partition on the center of a flow path merge at the measuring point to form a mixed layer with coherent structure. Fuel is supplied to this mixed layer with the flows so adjusted that the generated flame will attach to the partition on the lower velocity side. Acoustic excitation (at a sound pressure level of 100 dB to 120 dB) is performed in a speaker fitted on a wall on the higher velocity side. The paper mentions the results of the experiments as follows: the acoustic excitation produces such changes to diffusion flame in the plane shear layer as shorter flame and blue flame combustion and clarification of flame structures; as seen from spectral characteristics of temperature change in the flames, a flame acoustically excited strongly presents remarkable improvements in periodicity of the structure; as seen from sound pressure distribution in the flow direction at the measuring point, the flame zone of the flame acoustically excited strongly is positioned at the middle of the node and loop of a standing wave. 6 refs., 9 figs., 1 tab.

  14. 泡沫铝层合结构钢球磨煤机隔声罩降噪性能研究%Study on reduction noise properties of foamed aluminum laminated structure acoustical enclosure for ball mill

    Institute of Scientific and Technical Information of China (English)

    于英华; 余国军

    2012-01-01

    In order to explore a new way for reduction noise of ball mill,the view point of using foamed aluminum laminated structure in ball mill acoustical enclosures was put forward based noise properties of ball mill.The laminated structure plate used to ball mills acoustical enclosures was designed,reduction noise properties of it were studied by theoretical analysis and test.The results show that the new ball mill acoustical enclosures can improve the reduction noise and environmental protection capabilities of the ball mill acoustical enclosure.%为探索钢球磨煤机的降噪新途径,针对钢球磨煤机噪声的特点,提出将泡沫铝层合结构应用于钢球磨煤机隔声罩中的观点。设计了泡沫铝钢球磨煤机隔声罩板的层合结构,并运用理论分析和实验分析的方法对其降噪性能进行研究。结果表明,用泡沫铝层合结构制造钢球磨煤机隔声罩,可提高隔声罩的降噪性能,并可提高隔声罩环保性能。

  15. 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.

  16. The Theory of Adaptive Dispersion and Acoustic-phonetic Properties of Cross-language Lexical-tone Systems

    Science.gov (United States)

    Alexander, Jennifer Alexandra

    Lexical-tone languages use fundamental frequency (F0/pitch) to convey word meaning. About 41.8% of the world's languages use lexical tone (Maddieson, 2008), yet those systems are under-studied. I aim to increase our understanding of speech-sound inventory organization by extending to tone-systems a model of vowel-system organization, the Theory of Adaptive Dispersion (TAD) (Liljencrants and Lindblom, 1972). This is a cross-language investigation of whether and how the size of a tonal inventory affects (A) acoustic tone-space size and (B) dispersion of tone categories within the tone-space. I compared five languages with very different tone inventories: Cantonese (3 contour, 3 level tones); Mandarin (3 contour, 1 level tone); Thai (2 contour, 3 level tones); Yoruba (3 level tones only); and Igbo (2 level tones only). Six native speakers (3 female) of each language produced 18 CV syllables in isolation, with each of his/her language's tones, six times. I measured tonal F0 across the vowel at onset, midpoint, and offglide. Tone-space size was the F0 difference in semitones (ST) between each language's highest and lowest tones. Tone dispersion was the F0 distance (ST) between two tones shared by multiple languages. Following the TAD, I predicted that languages with larger tone inventories would have larger tone-spaces. Against expectations, tone-space size was fixed across level-tone languages at midpoint and offglide, and across contour-tone languages (except Thai) at offglide. However, within each language type (level-tone vs. contour-tone), languages with smaller tone inventories had larger tone spaces at onset. Tone-dispersion results were also unexpected. The Cantonese mid-level tone was further dispersed from a tonal baseline than the Yoruba mid-level tone; Cantonese mid-level tone dispersion was therefore greater than theoretically necessary. The Cantonese high-level tone was also further dispersed from baseline than the Mandarin high-level tone -- at midpoint

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Impact of layer and substrate properties on the surface acoustic wave velocity in scandium doped aluminum nitride based SAW devices on sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Gillinger, M., E-mail: manuel.gillinger@tuwien.ac.at; Knobloch, T.; Schneider, M.; Schmid, U. [Institute of Sensor and Actuator Systems, TU Wien, 1040 Vienna (Austria); Shaposhnikov, K.; Kaltenbacher, M. [Institute of Mechanics and Mechatronics, TU Wien, 1040 Vienna (Austria)

    2016-06-06

    This paper investigates the performance of surface acoustic wave (SAW) devices consisting of reactively sputter deposited scandium doped aluminum nitride (Sc{sub x}Al{sub 1-x}N) thin films as piezoelectric layers on sapphire substrates for wireless sensor or for RF-MEMS applications. To investigate the influence of piezoelectric film thickness on the device properties, samples with thickness ranging from 500 nm up to 3000 nm are fabricated. S{sub 21} measurements and simulations demonstrate that the phase velocity is predominantly influenced by the mass density of the electrode material rather than by the thickness of the piezoelectric film. Additionally, the wave propagation direction is varied by rotating the interdigital transducer structures with respect to the crystal orientation of the substrate. The phase velocity is about 2.5% higher for a-direction compared to m-direction of the sapphire substrate, which is in excellent agreement with the difference in the anisotropic Young's modulus of the substrate corresponding to these directions.

  2. DEPSCoR FY 99: Use of Stochastic Modeling of Stratigraphic Relationships in High Resolution Seismic Reflection Data for Prediction of the Distribution of Acoustic and Geotechnical Property Variability in Near Surface Sediments on the East China Sea Continental Margin

    Science.gov (United States)

    2016-06-13

    Distribution of Acoustic and Geotechnical Property Variability in Near Surface Sediments on the East China Sea Continental Margin Louis R. Bartek Department of...East China Sea Continental Margin 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER...collecting data. During survey 221099 in the East China Sea (ECS) and the Yellow Sea (YS) we collected 191 km of 210 cubic inch Generator Injector Air

  3. 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...

  4. 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 ...

  5. Piezoelectric La{sub 3}Ga{sub 5.3}Ta{sub 0.5}Al{sub 0.2}O{sub 14} crystal: growth, crystal structure perfection, piezoelectric, and acoustic properties

    Energy Technology Data Exchange (ETDEWEB)

    Roshchupkin, Dmitry; Plotitcyna, Olga; Irzhak, Dmitry; Emelin, Evgenii; Fahrtdinov, Rashid [Institute of Microelectronics Technology and High-Purity Materials Russian Academy of Sciences, Chernogolovka, Moscow District (Russian Federation); Ortega, Luc [Univ. Paris-Sud, CNRS, UMR 8502, Laboratoire de Physique des Solides, Orsay Cedex (France); Alenkov, Vladimir; Buzanov, Oleg [FOMOS Materials Co., Moscow (Russian Federation)

    2014-09-15

    A five-component crystal of lanthanum-gallium silicate group La{sub 3}Ga{sub 5.3}Ta{sub 0.5}Al{sub 0.2}O{sub 14} (LGTA) was grown by the Czochralski method. The LGTA crystal possesses unique thermal properties and substitution of Al for Ga in the unit cell leads to a substantial increase of electrical resistance at high temperatures. The unit cell parameters of LGTA were determined by powder diffraction. X-ray topography was used to study the crystal structure perfection: the growth banding normal to the growth axis were visualized. The independent piezoelectric constants d{sub 11} and d{sub 14} were measured by X-ray diffraction in the Bragg and Laue geometries. Excitation and propagation of surface acoustic waves were studied by the double-crystal X-ray diffraction at the BESSY II synchrotron radiation source. The analysis of the diffraction spectra of acoustically modulated crystals permitted the determination of the velocity of acoustic wave propagation and the power flow angles in different acoustic cuts of the LGTA crystal. (orig.)

  6. Acoustical, Physical, and Biological Properties of Surface Sediment Cores Collected from Long Island Sound, August 27-28, 1980.

    Science.gov (United States)

    1982-06-01

    for shallow-water coastal sediments. Sampling designs which either define small-scale sediment property varia- bility or make measurements over long...transducer was epoxied at one end into a 15 mm long, 10 mm wide window machined into a 2.4 mm thick Phenolic Sheet pitted with Scotch Cast 8 (Fig. 2). The...log 2 of grain size in mm) with an ATM Sonic Sifter and each fraction was individually weighed to determine the gravel and sand particle size

  7. Monitoring microbe-induced physical property changes using high-frequency acoustic waveform data: Toward the development of a microbial megascope

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Kenneth Hurst

    2002-05-20

    A laboratory investigation was undertaken to determine the effect of microbe generated gas bubbles in controlled, saturated sediment columns utilizing a novel technique involving acoustic wave propagation. Specifically, the effect of denitrifying bacteria on saturated flow conditions was evaluated in light of the stimulated production of N{sub 2} gas and the resulting plugging of the pore throats. The propagation of high frequency acoustic waves through the sediment columns was used to locate those regions in the column where gas accumulation occurred. Over a period of six weeks, regions of gas accumulation resulted in the attenuation of acoustic wave energies with the decreases in amplitude typically greater than one order of magnitude.

  8. Sensor development and calibration for acoustic neutrino detection in ice

    OpenAIRE

    Karg, Timo; Bissok, Martin; Laihem, Karim; Semburg, Benjamin; Tosi, Delia; Collaboration, for the IceCube

    2009-01-01

    A promising approach to measure the expected low flux of cosmic neutrinos at the highest energies (E > 1 EeV) is acoustic detection. There are different in-situ test installations worldwide in water and ice to measure the acoustic properties of the medium with regard to the feasibility of acoustic neutrino detection. The parameters of interest include attenuation length, sound speed profile, background noise level and transient backgrounds. The South Pole Acoustic Test Setup (SPATS) has been ...

  9. Acoustics of two-phase pipe flows

    OpenAIRE

    Dijk, van, Nico M.

    2005-01-01

    Acoustic signals that are recorded in oil pipelines contain information about the flow. In order to extract this information from the pressure recordings, detailed knowledge about the transmission properties of sound waves in the pipes is required.

  10. 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.

  11. 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...

  12. 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...

  13. Iso-acoustic focusing of cells for size-insensitive acousto-mechanical phenotyping

    DEFF Research Database (Denmark)

    Augustsson, Per; Karlsen, Jonas Tobias; Su, Hao-Wei

    2016-01-01

    Mechanical phenotyping of single cells is an emerging tool for cell classification, enabling assessment of effective parameters relating to cells' interior molecular content and structure. Here, we present iso-acoustic focusing, an equilibrium method to analyze the effective acoustic impedance......-acoustic focusing of cell lines and leukocytes, showing that acoustic properties provide phenotypic information independent of size....

  14. Computerized acoustical characterization system of medical phantoms

    Science.gov (United States)

    Nazihah, M. D.; Kadri, S.; Yaacob, M. I. H.; Rosly, J.

    2013-05-01

    The development of a computerized acoustical characterization system of medical phantoms is described in this paper. The system employs the insertion technique and it was developed using LabView 2011 where the ultrasound signal was acquired through the interfacing scheme of an oscilloscope to a personal computer. The system performance was validated by comparing measured acoustical properties with values obtained from the previous studies. Other than faster measurement time, the developed system carried percentage difference at less than 1.00% for all of the acoustical properties measurements at 23.0°C to 25.0°C respectively.

  15. 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.

  16. 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.

  17. 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...

  18. 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.

  19. 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.

  20. 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.

  1. Opto-Acoustic Biosensing with Optomechanofluidic Resonators

    CERN Document Server

    Zhu, Kaiyuan; Carmon, Tal; Fan, Xudong; Bahl, Gaurav

    2014-01-01

    Opto-mechano-fluidic resonators (OMFRs) are a unique optofluidics platform that can measure the acoustic properties of fluids and bioanalytes in a fully-contained microfluidic system. By confining light in ultra-high-Q whispering gallery modes of OMFRs, optical forces such as radiation pressure and electrostriction can be used to actuate and sense structural mechanical vibrations spanning MHz to GHz frequencies. These vibrations are hybrid fluid-shell modes that entrain any bioanalyte present inside. As a result, bioanalytes can now reflect their acoustic properties on the optomechanical vibrational spectrum of the device, in addition to optical property measurements with existing optofluidics techniques. In this work, we investigate acoustic sensing capabilities of OMFRs using computational eigenfrequency analysis. We analyze the OMFR eigenfrequency sensitivity to bulk fluid-phase materials as well as nanoparticles, and propose methods to extract multiple acoustic parameters from multiple vibrational modes. ...

  2. Density-near-zero using the acoustically induced transparency of a Fano acoustic resonator

    KAUST Repository

    Elayouch, A.

    2017-01-05

    We report experimental results of near-zero mass density involving an acoustic metamaterial supporting Fano resonance. For this, we designed and fabricated an acoustic resonator with two closely coupled modes and measured its transmission properties. Our study reveals that the phenomenon of acoustically induced transparency is accompanied by an effect of near-zero density. Indeed, the dynamic effective parameters obtained from experimental data show the presence of a frequency band where the effective mass density is close to zero, with high transmission levels reaching 0.7. Furthermore, we demonstrate that such effective parameters lead to wave guiding in a 90-degrees-bent channel. This kind of acoustic metamaterial can, therefore, give rise to acoustic functions like controlling the wavefront, which may lead to very promising applications in acoustic cloacking or imaging.

  3. A sound future for acoustic metamaterials.

    Science.gov (United States)

    Cummer, Steven

    2017-05-01

    The field of acoustic metamaterials borrowed ideas from electromagnetics and optics to create engineered structures that exhibit desired fluid or fluid-like properties for the propagation of sound. These metamaterials offer the possibility of manipulating and controlling sound waves in ways that are challenging or impossible with conventional materials. Metamaterials with zero, or 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. And active acoustic metamaterials use external control and power to create effective material properties that are fundamentally not possible with passive structures. Challenges remain, including the development of efficient techniques for fabricating large-scale metamaterial structures and, critically, converting exciting laboratory experiments into practically useful devices. In this presentation, I will outline the recent history of the field, describe some of the designs and properties of materials with unusual acoustic parameters, discuss examples of extreme manipulation of sound, and finally, provide a personal perspective on future directions in the field.

  4. Monitoring microbe-induced physical property changes using high-frequency acoustic waveform data: Toward the development of a microbial megascope

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Kenneth Hurst [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    A laboratory investigation was undertaken to determine the effect of microbe generated gas bubbles in controlled, saturated sediment columns utilizing a novel technique involving acoustic wave propagation. Specifically, the effect of denitrifying bacteria on saturated flow conditions was evaluated in light of the stimulated production of N2 gas and the resulting plugging of the pore throats. The propagation of high frequency acoustic waves through the sediment columns was used to locate those regions in the column where gas accumulation occurred. Over a period of six weeks, regions of gas accumulation resulted in the attenuation of acoustic wave energies with the decreases in amplitude typically greater than one order of magnitude.

  5. 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...

  6. A Theory Analysis and Experimental Study on Acoustic Transmission Properties in Drill String%钻柱中声波传播特性理论分析与试验研究

    Institute of Scientific and Technical Information of China (English)

    谢慧; 江正清; 王新峰; 蔡文军

    2012-01-01

    In order to validate the acoustic transmission properties in drill string,and get the right frequency point or band for underground information transmission, using φ127. 0 mm drill pipe as the research object,and analyzed the relationship between frequency and wave number of drill pipes with different lengths based on the frequency equation of ideal drill string. The analysis results show that unevenness of drill pipe length will lead to smaller intersection of drill string pass band; if each cycle of drill string consists of drill pipes with different lengths, the pass band will become narrow, or, in some frequency bands form very wide stop band because of no overlap. Based on transient response equation of ideal drill string, the reflection action of drill pipe connector to acoustic wave has been analyzed, to get transient properties of acoustic wave through a lot of drill pipes. Through indoor experiments on acoustic transmission properties with the full size joint, 1. 5 m-long drill pipe,we studied the transmission properties of different-frequency acoustic waves in different-length drill strings, verified that comb filter and dispersion phenomenon exist in the acoustic transmission in drill string,and got some frequency scope or frequency band that was suitable for acoustic transmission in drill string.%为验证声波在钻柱中的传播特性,获取适合传输井下信息的频率点或频段,以φ127.0 mm钻杆为研究对象,基于理想钻柱的频率方程,分析了不同长度钻杆的频率与波数的关系.分析认为,钻杆长度的不均匀性将导致钻柱通频带的交集缩小,若钻柱每个周期由不同长度的钻杆连接组成,通带将变窄,甚至在某些频带上因没有重叠部分而形成很宽的阻带.基于理想钻柱的瞬态响应方程,分析了钻杆接头对声波的反射作用,得到了声波通过多根钻杆后的瞬态特性.在室内采用每根长1.5m的钻杆短节,进行了全尺寸接头钻杆短节声波

  7. 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...

  8. 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....

  9. 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

  10. Acoustical Properties of Mud Sediments

    Science.gov (United States)

    2015-09-30

    of the late William Carey and Its objective was to develop a model for the interaction of clay mineral platelets based on fundamental physical...structure developed by Pierce and Carey [1]. The first key step in the approach is formulating a hypothesized physics-based model. The electric field of...from inversions using the extended Mallock-Wood equation. Employing measurements by Carey at Dodge Pond, we found that the solid volume fraction

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. Influence of the parameters of a high-frequency acoustic wave on the structure, properties, and plastic flow of metal in the zone of a joint of materials welded by ultrasound-assisted explosive welding

    Science.gov (United States)

    Peev, A. P.; Kuz'min, S. V.; Lysak, V. I.; Kuz'min, E. V.; Dorodnikov, A. N.

    2017-05-01

    The results of an investigation of the influence of the parameters of high-frequency acoustic wave on the structure and properties of the zone of joint of homogeneous metals bonded by explosive welding under the action of ultrasound have been presented. The influence of the frequency and amplitude of ultrasonic vibrations on the structure and properties of the explosively welded joints compared with the samples welded without the application of ultrasound has been established. The action of high-frequency acoustic waves on the metal leads to a reduction in the dynamic yield stress, which changes the properties of the surface layers of the metal and the conditions of the formation of the joint of the colliding plates upon the explosive welding. It has been shown that the changes in the length and amplitude of waves that arise in the weld joint upon the explosive welding with the simultaneous action of ultrasonic vibrations are connected with a decrease in the magnitude of the deforming pulse and time of action of the compressive stresses that exceed the dynamic yield stress beyond the point of contact.

  17. 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.

  18. 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.

  19. A Comparison of the Single-sided (Gen II) and Double-sided (Gen I) Combat Arms Earplugs (CAE): Acoustic Properties, Human Performance, and User Acceptance

    Science.gov (United States)

    2012-12-01

    acquisition of the earplug by the U.S. Army. 15. SUBJECT TERMS Combat Arms Earplug, nonlinear hearing protection, perceptual effects of hearing...compass reading of the position of the laser pointer. In order to prevent visual detection of the loudspeakers, black acoustically- transparent cloth... perceptual assessment both types of CAE similarly affected speech intelligibility and localization accuracy indicating that if perceptual differences

  20. Environmental Acoustics and Intensity Vector Acoustics with Emphasis on Shallow Water Effects and the Sea Surface

    Science.gov (United States)

    2014-09-30

    Vector Acoustics with Emphasis on Shallow Water Effects and the Sea Surface Peter H. Dahl Applied Physics Laboratory University of Washington...To understand and predict key properties of the signal intensity vector field as it propagates away from an active sound source, with emphasis is on...exploit acoustic vector field properties (velocity, acceleration, intensity) much more than today’s. Furthermore, advancement of current Navy

  1. Experimental study of geo-acoustic inversion uncertainty due to ocean sound-speed fluctuations.

    NARCIS (Netherlands)

    Siderius, M.; Nielsen, P.L.; Sellschopp, J.; Snellen, M.; Simons, D.G.

    2001-01-01

    Acoustic data measured in the ocean fluctuate due to the complex time-varying properties of the channel. When measured data are used for model-based, geo-acoustic inversion, how do acoustic fluctuations impact estimates for the seabed properties? In May 1999 SACLANT Undersea Research Center and

  2. Experimental study of geo-acoustic inversion uncertainty due to ocean sound-speed fluctuations.

    NARCIS (Netherlands)

    Siderius, M.; Nielsen, P.L.; Sellschopp, J.; Snellen, M.; Simons, D.G.

    2001-01-01

    Acoustic data measured in the ocean fluctuate due to the complex time-varying properties of the channel. When measured data are used for model-based, geo-acoustic inversion, how do acoustic fluctuations impact estimates for the seabed properties? In May 1999 SACLANT Undersea Research Center and TNO-

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

    Science.gov (United States)

    Hughes, William O.; McNelis, Anne M.

    2014-01-01

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

  4. 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...

  5. 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 ...

  6. 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...

  7. 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).

  8. 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.

  9. 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.

  10. Analysis and experimental validation of the middle-frequency vibro-acoustic coupling property for aircraft structural model based on the wave coupling hybrid FE-SEA method

    Science.gov (United States)

    Yan, Yunju; Li, Pengbo; Lin, Huagang

    2016-06-01

    The finite element (FE) method is suitable for low frequency analysis and the statistical energy analysis (SEA) for high frequency analysis, but the vibro-acoustic coupling analysis at middle frequency, especially with a certain range of uncertainty system, requires some new methods. A hybrid FE-SEA method is proposed in this study and the Monte Carlo method is used to check the hybrid FE-SEA method through the energy response analysis of a beam-plate built-up structure with some uncertainty, and the results show that two kinds of calculation results match well consistently. Taking the advantage of the hybrid FE-SEA method, the structural vibration and the cabin noise field responses under the vibro-acoustic coupling for an aircraft model are numerically analyzed, and, also, the corresponding experiment is carried out to verify the simulated results. Results show that the structural vibration responses at low frequency accord well with the experiment, but the error at high frequency is greater. The error of sound pressure response level in cabin throughout the spectrum is less than 3 dB. The research proves the reliability of the method proposed in this paper. This indicates that the proposed method can overcome the strict limitations of the traditional method for a large complex structure with uncertainty factors, and it can also avoid the disadvantages of solving complex vibro-acoustic system using the finite element method or statistical energy analysis in the middle frequency.

  11. 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.

  12. Active acoustic metamaterials reconfigurable in real-time

    CERN Document Server

    Popa, Bogdan-Ioan; Konneker, Adam; Cummer, Steven A

    2015-01-01

    A major limitation of current acoustic metamaterials is that their acoustic properties are either locked into place once fabricated or only modestly tunable, tying them to the particular application for which they are designed. We present in this paper a design approach that yields active metamaterials whose physical structure is fixed, yet their local acoustic response can be changed almost arbitrarily and in real-time by configuring the digital electronics that control the metamaterial acoustic properties. We demonstrate experimentally this approach by designing a metamaterial slab configured to act as a very thin acoustic lens that manipulates differently three identical, consecutive pulses incident on the lens. Moreover, we show that the slab can be configured to implement simultaneously various roles, such as that of a lens and beam steering device. Finally, we show that the metamaterial slab is suitable for efficient second harmonic acoustic imaging devices capable to overcome the diffraction limit of l...

  13. 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...

  14. 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.

  15. Ultra-broadband sound absorption by acoustic metamaterials

    Science.gov (United States)

    Jiang, Xue; Liang, Bin; Cheng, Jian-Chun

    2015-03-01

    Metamaterials with extraordinary properties unavailable in nature have opened up new design possibilities. Acoustic absorbers are of particular significances for acoustics-based devices and find applications in various scenarios, but subject to the inherent restriction of the natural acoustical parameters and limited operating bandwidth. We report the theoretical design, numerical calculation and experimental study on the realization of a metamaterial-based acoustic absorber with a simple yet efficient structure. The proposed acoustic absorber works in an ultra-broad band without restricted by the material type or requiring extra absorbing material. Such distinct effects stem from the localization and dissipation of different spectrum components at predesigned spatial positions. Theoretical predictions developed based on classical acoustic theory agree well with numerical and experimental results. The realization of ultra-broadband acoustic absorber with unique properties of stiffness and environmental-friendliness has paved the way for designing conceptual acoustic devices, and has potential applications in situations with special requirements on acoustic absorption characteristics. Key Laboratory of Modern Acoustics, MOE, Department of Physics, Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China.

  16. Cyclones and attractive streaming generated by acoustical vortices.

    Science.gov (United States)

    Riaud, Antoine; Baudoin, Michael; Thomas, Jean-Louis; Bou Matar, Olivier

    2014-07-01

    Acoustical and optical vortices have attracted great interest due to their ability to capture and manipulate particles with the use of radiation pressure. Here we show that acoustical vortices can also induce axial vortical flow reminiscent of cyclones, whose topology can be controlled by adjusting the properties of the acoustical beam. In confined geometry, the phase singularity enables generating "attractive streaming" with the flow directed toward the transducer. This opens perspectives for contactless vortical flow control.

  17. Influence of viscoelasticity and interfacial slip on acoustic wave sensors

    OpenAIRE

    McHale, G; Lucklum, R.; Newton, MI; Cowen, JA

    2000-01-01

    Acoustic wave devices with shear horizontal displacements, such as quartz crystal microbalances (QCM) and shear horizontally polarised surface acoustic wave (SH-SAW) devices provide sensitive probes of changes at solid-solid and solid- liquid interfaces. Increasingly the surfaces of acoustic wave devices are being chemically or physically modified to alter surface adhesion or coated with one or more layers to amplify their response to any change of mass or material properties. In this work, w...

  18. Cyclones and attractive streaming generated by acoustical vortices

    CERN Document Server

    Riaud, Antoine; Thomas, Jean-Louis; Matar, Olivier Bou

    2014-01-01

    Acoustical and optical vortices have attracted large interest due to their ability in capturing and manipulating particles with the use of the radiation pressure. Here we show that acoustical vortices can also induce axial vortical flow reminiscent of cyclones whose topology can be controlled by adjusting the properties of the acoustical beam. In confined geometry, the phase singularity enables generating attractive streaming with a flow directed toward the transducer. This opens perspectives for contact-less vortical flow control.

  19. Sustainable Acoustic Metasurfaces for Sound Control

    Directory of Open Access Journals (Sweden)

    Paola Gori

    2016-01-01

    Full Text Available Sound attenuation with conventional acoustic materials is subject to the mass law and requires massive and bulky structures at low frequencies. A possible alternative solution is provided by the use of metamaterials, which are artificial materials properly engineered to obtain properties and characteristics that it is not possible to find in natural materials. Theory and applications of metamaterials, already consolidated in electromagnetism, can be extended to acoustics; in particular, they can be applied to improve the properties of acoustical panels. The design of acoustic metasurfaces that could effectively control transmitted sound in unconventional ways appears a significant subject to be investigated, given its wide-ranging possible applications. In this contribution, we investigate the application of a metasurface-inspired technique to achieve the acoustical insulation of an environment. The designed surface has subwavelength thickness and structuring and could be realized with cheap, lightweight and sustainable materials. We present a few examples of such structures and analyze their acoustical behavior by means of full-wave simulations.

  20. 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.

  1. New acoustics, based on lefthanded media

    Science.gov (United States)

    Gan, Woon S.

    2012-05-01

    Metamaterials are materials with artificial properties defined by their sub-wavelength structure rather than their chemical composition. With the arrival of photonic crystals and phononic crystals, the fabrication of metamaterials which do not exist in nature become a reality. We discovered parity invariance in acoustical field equation. We also show that negative refraction is a special case of coordinates transformation (used in acoustical cloaking) when the determinant of the direction cosines matrix equals -1 and we develop a unifed theory for negative refraction and cloaking. Gauge invariance approach also removes the ambiguity problem of positive sign and negative sign when using the dispersion relation for the negative refractive index. Lefthanded materials produce Poynting vector in opposite direction to wave propagation. This gives rise to new phenomena in refraction, diffraction, and scattering of acoustic waves in the material‥ These three are the basic mechanisms of sound propagation in medium. Hence we call this new acoustics.

  2. Acoustic phase lenses in superfluid He as models of composite spacetimes in general relativity Classical and quantum properties with provision for spatial topology

    CERN Document Server

    Zloshchastiev, K G

    1999-01-01

    In the spirit of the well-known analogy between inviscid fluids and pseudo-Riemannian manifolds we study spherical thin shells in the static superfluid. Thin shells turn to be the interfaces dividing the superfluid into the pairs of domains, for instance, phases ``superfluid A - superfluid B'' or ``impurity - superfluid''. It is shown that such shells form the acoustic lenses. The exact equations of motion of the lens interfaces are obtained. Also we consider the quantum mechanical aspects, thereby energy spectra for bound states of the lenses are calculated taking into account the spatial topology of the black hole and wormhole type.

  3. 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

  4. 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...

  5. 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...

  6. Acoustics of the piezo-electric pressure probe

    Science.gov (United States)

    Dutt, G. S.

    1974-01-01

    Acoustical properties of a piezoelectric device are reported for measuring the pressure in the plasma flow from an MPD arc. A description and analysis of the acoustical behavior in a piezoelectric probe is presented for impedance matching and damping. The experimental results are presented in a set of oscillographic records.

  7. Final evaluation of the acoustics of the APS conference center

    Energy Technology Data Exchange (ETDEWEB)

    Restrepo, J.M.

    1995-11-01

    Along with a description of the changes that I prescribed on the original design, this report is an evaluation of the acoustical properties of the new Advanced Photon Source Auditorium at Argonne National Laboratory. Acoustical deficiencies in the hall are presented with several options for their expedient and economical solution.

  8. Model dependence of the multi-transonic behaviour, stability properties and the corresponding acoustic geometry for accretion onto rotating black holes

    Science.gov (United States)

    Saha, Sonali; Sen, Sharmistha; Nag, Sankhasubhra; Raychowdhury, Suparna; Das, Tapas K.

    2016-02-01

    Stationary, multi-transonic, integral solutions of hydrodynamic axisymmetric accretion onto a rotating black hole have been compared for different geometrical configurations of the associated accretion disc structures described using the polytropic as well as the isothermal equations of state. Such analysis is performed for accretion under the influence of generalised post Newtonian pseudo Kerr black hole potential. The variations of the stationary shock characteristics with black hole spin have been studied in details for all the disc models and are compared for the flow characterised by the two aforementioned equations of state. Using a novel linear perturbation technique it has been demonstrated that the aforementioned stationary solutions are stable, at least upto an astrophysically relevant time scale. It has been demonstrated that the emergence of the horizon related gravity like phenomena (the analogue gravity effects) is a natural consequence of such stability analysis, and the corresponding acoustic geometry embedded within the transonic accretion can be constructed for the propagation of the linear acoustic perturbation of the mass accretion rate. The analytical expression for the associated sonic surface gravity κ has been obtained self consistently. The variations of κ with the black hole spin parameter for all different geometric configurations of matter and for various thermodynamic equations of state have been demonstrated.

  9. Principles and effects of acoustic cavitation - A review

    Directory of Open Access Journals (Sweden)

    Corina GÂMBUŢEANU

    2013-12-01

    Full Text Available In the recent years, food industry has shown a real interest in ultrasound use because of its effect on physical, biochemical and microbial properties of food systems. In order to better understand how the acoustic cavity effects could be best applied in food industry, a review on acoustic cavitation and its effects was done. The present paper describes in detail the basic principles underlying the effects of ultrasounds on food processing applications. It also provides theoretical background on acoustic cavitation and ultrasound production method. Moreover, harnessing mechanic, optic, chemical and biological effects of acoustic cavitation in food industry were briefly highlighted.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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...

  15. 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...

  16. 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.

  17. 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...

  18. 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...

  19. Surface acoustic wave propagation properties in 0.67Pb(Mg1∕3Nb2∕3)O3-0.33PbTiO3 single crystal poled along [111]c

    Science.gov (United States)

    Li, Xiuming; Zhang, Rui; Huang, Naixing; Lü, Tianquan; Cao, Wenwu

    2009-01-01

    Surface acoustic wave (SAW) propagation properties in relaxor-based 0.67Pb(Mg1∕3Nb2∕3)O3-0.33PbTiO3 (PMN-33%PT) ferroelectric single crystals poled along [111]c has been analyzed theoretically. We found that the X-cut PMN-33%PT has lower phase velocity and higher electromechanical coupling coefficient compared to traditional piezoelectric materials. The power flow angle (PFA) can be zero in specific directions, which could drastically improve the performance of SAW devices. Our theoretical results indicate that the direction about 5° canted from [111]c is the optimum direction for the X-cut [111]c poled crystals in SAW device applications. Characteristic curves were also obtained for the phase velocity, electromechanical coupling coefficient, and PFA in Z-cut single-domain PMN-33%PT single crystals. PMID:20069133

  20. Classifying acoustic signals into phoneme categories: average and dyslexic readers make use of complex dynamical patterns and multifractal scaling properties of the speech signal

    Directory of Open Access Journals (Sweden)

    Fred Hasselman

    2015-03-01

    Full Text Available Several competing aetiologies of developmental dyslexia suggest that the problems with acquiring literacy skills are causally entailed by low-level auditory and/or speech perception processes. The purpose of this study is to evaluate the diverging claims about the specific deficient peceptual processes under conditions of strong inference. Theoretically relevant acoustic features were extracted from a set of artificial speech stimuli that lie on a /bAk/-/dAk/ continuum. The features were tested on their ability to enable a simple classifier (Quadratic Discriminant Analysis to reproduce the observed classification performance of average and dyslexic readers in a speech perception experiment. The ‘classical’ features examined were based on component process accounts of developmental dyslexia such as the supposed deficit in Envelope Rise Time detection and the deficit in the detection of rapid changes in the distribution of energy in the frequency spectrum (formant transitions. Studies examining these temporal processing deficit hypotheses do not employ measures that quantify the temporal dynamics of stimuli. It is shown that measures based on quantification of the dynamics of complex, interaction-dominant systems (Recurrence Quantification Analysis and the multifractal spectrum enable QDA to classify the stimuli almost identically as observed in dyslexic and average reading participants. It seems unlikely that participants used any of the features that are traditionally associated with accounts of (impaired speech perception. The nature of the variables quantifying the temporal dynamics of the speech stimuli imply that the classification of speech stimuli cannot be regarded as a linear aggregate of component processes that each parse the acoustic signal independent of one another, as is assumed by the ‘classical’ aetiologies of developmental dyslexia. It is suggested that the results imply that the differences in speech perception

  1. Classifying acoustic signals into phoneme categories: average and dyslexic readers make use of complex dynamical patterns and multifractal scaling properties of the speech signal.

    Science.gov (United States)

    Hasselman, Fred

    2015-01-01

    Several competing aetiologies of developmental dyslexia suggest that the problems with acquiring literacy skills are causally entailed by low-level auditory and/or speech perception processes. The purpose of this study is to evaluate the diverging claims about the specific deficient peceptual processes under conditions of strong inference. Theoretically relevant acoustic features were extracted from a set of artificial speech stimuli that lie on a /bAk/-/dAk/ continuum. The features were tested on their ability to enable a simple classifier (Quadratic Discriminant Analysis) to reproduce the observed classification performance of average and dyslexic readers in a speech perception experiment. The 'classical' features examined were based on component process accounts of developmental dyslexia such as the supposed deficit in Envelope Rise Time detection and the deficit in the detection of rapid changes in the distribution of energy in the frequency spectrum (formant transitions). Studies examining these temporal processing deficit hypotheses do not employ measures that quantify the temporal dynamics of stimuli. It is shown that measures based on quantification of the dynamics of complex, interaction-dominant systems (Recurrence Quantification Analysis and the multifractal spectrum) enable QDA to classify the stimuli almost identically as observed in dyslexic and average reading participants. It seems unlikely that participants used any of the features that are traditionally associated with accounts of (impaired) speech perception. The nature of the variables quantifying the temporal dynamics of the speech stimuli imply that the classification of speech stimuli cannot be regarded as a linear aggregate of component processes that each parse the acoustic signal independent of one another, as is assumed by the 'classical' aetiologies of developmental dyslexia. It is suggested that the results imply that the differences in speech perception performance between average and

  2. Advanced Concepts for Underwater Acoustic Channel Modeling

    Science.gov (United States)

    Etter, P. C.; Haas, C. H.; Ramani, D. V.

    2014-12-01

    This paper examines nearshore underwater-acoustic channel modeling concepts and compares channel-state information requirements against existing modeling capabilities. This process defines a subset of candidate acoustic models suitable for simulating signal propagation in underwater communications. Underwater-acoustic communications find many practical applications in coastal oceanography, and networking is the enabling technology for these applications. Such networks can be formed by establishing two-way acoustic links between autonomous underwater vehicles and moored oceanographic sensors. These networks can be connected to a surface unit for further data transfer to ships, satellites, or shore stations via a radio-frequency link. This configuration establishes an interactive environment in which researchers can extract real-time data from multiple, but distant, underwater instruments. After evaluating the obtained data, control messages can be sent back to individual instruments to adapt the networks to changing situations. Underwater networks can also be used to increase the operating ranges of autonomous underwater vehicles by hopping the control and data messages through networks that cover large areas. A model of the ocean medium between acoustic sources and receivers is called a channel model. In an oceanic channel, characteristics of the acoustic signals change as they travel from transmitters to receivers. These characteristics depend upon the acoustic frequency, the distances between sources and receivers, the paths followed by the signals, and the prevailing ocean environment in the vicinity of the paths. Properties of the received signals can be derived from those of the transmitted signals using these channel models. This study concludes that ray-theory models are best suited to the simulation of acoustic signal propagation in oceanic channels and identifies 33 such models that are eligible candidates.

  3. Coupled vibro-acoustic model updating using frequency response functions

    Science.gov (United States)

    Nehete, D. V.; Modak, S. V.; Gupta, K.

    2016-03-01

    Interior noise in cavities of motorized vehicles is of increasing significance due to the lightweight design of these structures. Accurate coupled vibro-acoustic FE models of such cavities are required so as to allow a reliable design and analysis. It is, however, experienced that the vibro-acoustic predictions using these models do not often correlate acceptably well with the experimental measurements and hence require model updating. Both the structural and the acoustic parameters addressing the stiffness as well as the damping modeling inaccuracies need to be considered simultaneously in the model updating framework in order to obtain an accurate estimate of these parameters. It is also noted that the acoustic absorption properties are generally frequency dependent. This makes use of modal data based methods for updating vibro-acoustic FE models difficult. In view of this, the present paper proposes a method based on vibro-acoustic frequency response functions that allow updating of a coupled FE model by considering simultaneously the parameters associated with both the structural as well as the acoustic model of the cavity. The effectiveness of the proposed method is demonstrated through numerical studies on a 3D rectangular box cavity with a flexible plate. Updating parameters related to the material property, stiffness of joints between the plate and the rectangular cavity and the properties of absorbing surfaces of the acoustic cavity are considered. The robustness of the method under presence of noise is also studied.

  4. Subwavelength diffractive acoustics and wavefront manipulation with a reflective acoustic metasurface

    Science.gov (United States)

    Wang, Wenqi; Xie, Yangbo; Popa, Bogdan-Ioan; Cummer, Steven A.

    2016-11-01

    Acoustic metasurfaces provide useful wavefront shaping capabilities, such as beam steering, acoustic focusing, and asymmetric transmission, in a compact structure. Most acoustic metasurfaces described in the literature are transmissive devices and focus their performance on steering sound beam of the fundamental diffractive order. In addition, the range of incident angles studied is usually below the critical incidence predicted by generalized Snell's law of reflection. In this work, we comprehensively analyze the wave interaction with a generic periodic phase-modulating structure in order to predict the behavior of all diffractive orders, especially for cases beyond critical incidence. Under the guidance of the presented analysis, a broadband reflective metasurface is designed based on an expanded library of labyrinthine acoustic metamaterials. Various local and nonlocal wavefront shaping properties are experimentally demonstrated, and enhanced absorption of higher order diffractive waves is experimentally shown for the first time. The proposed methodology provides an accurate approach for predicting practical diffracted wave behaviors and opens a new perspective for the study of acoustic periodic structures. The designed metasurface extends the functionalities of acoustic metasurfaces and paves the way for the design of thin planar reflective structures for broadband acoustic wave manipulation and extraordinary absorption.

  5. Origami acoustics: using principles of folding structural acoustics for simple and large focusing of sound energy

    Science.gov (United States)

    Harne, Ryan L.; Lynd, Danielle T.

    2016-08-01

    Fixed in spatial distribution, arrays of planar, electromechanical acoustic transducers cannot adapt their wave energy focusing abilities unless each transducer is externally controlled, creating challenges for the implementation and portability of such beamforming systems. Recently, planar, origami-based structural tessellations are found to facilitate great versatility in system function and properties through kinematic folding. In this research we bridge the physics of acoustics and origami-based design to discover that the simple topological reconfigurations of a Miura-ori-based acoustic array yield many orders of magnitude worth of reversible change in wave energy focusing: a potential for acoustic field morphing easily obtained through deployable, tessellated architectures. Our experimental and theoretical studies directly translate the roles of folding the tessellated array to the adaptations in spectral and spatial wave propagation sensitivities for far field energy transmission. It is shown that kinematic folding rules and flat-foldable tessellated arrays collectively provide novel solutions to the long-standing challenges of conventional, electronically-steered acoustic beamformers. While our examples consider sound radiation from the foldable array in air, linear acoustic reciprocity dictates that the findings may inspire new innovations for acoustic receivers, e.g. adaptive sound absorbers and microphone arrays, as well as concepts that include water-borne waves.

  6. Acoustic manipulation of oscillating spherical bodies: Emergence of axial negative acoustic radiation force

    Science.gov (United States)

    Rajabi, Majid; Mojahed, Alireza

    2016-11-01

    In this paper, emergence of negative axial acoustic radiation force on a rigid oscillating spherical body is investigated for acoustic manipulation purposes. The problem of plane acoustic wave scattering from an oscillating spherical body submerged in an ideal acoustic fluid medium is solved. For the case of oscillating direction collinear with the wave propagation wave number vector (desired path), it has been shown that the acoustic radiation force, as a result of nonlinear acoustic wave interaction with bodies can be expressed as a linear function of incident wave field and the oscillation properties of the oscillator (i.e., amplitude and phase of oscillation). The negative (i.e., pulling effects) and positive (i.e., pushing effects) radiation force situations are divided in oscillation complex plane with a specific frequency-dependant straight line. This characteristic line defines the radiation force cancellation state. In order to investigate the stability of the mentioned manipulation strategy, the case of misaligned oscillation of sphere with the wave propagation direction is studied. The proposed methodology may suggest a novel concept of single-beam acoustic handling techniques based on smart carriers.

  7. 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.

  8. Acoustic and Volumetric Properties of Mixture of (N,N-Dimethylacetamide + Ethyl Acrylate with 1-Butanol or iso-Butanol or t-Butanol at 308.15 K

    Directory of Open Access Journals (Sweden)

    M. Kondaiah

    2014-01-01

    Full Text Available Densities, ρ, and ultrasonic speeds, u of mixtures of 1-butanol or iso-butanol or t-butanol with equimolar mixture of (N,N-dimethylacetamide + Ethyl acrylate over the entire composition range have been measured at T=308.15 K. Using the experimental results, deviation in ultrasonic speed, Δu, deviation in isentropic compressibility, Δks, excess molar volume, VmE, excess intermolecular free length, LfE, and excess acoustic impedance, ZE, have been calculated. The variation of these properties with composition of the mixtures has been discussed in terms of molecular interactions in these mixtures. The deviation/excess properties have been fitted to Redlich-Kister type polynomial and the corresponding standard deviations have been calculated. Negative values of VmE, Δks, and LfE and positive values of Δu, and ZE are observed over the entire composition range. The observed negative and positive values of deviation/excess properties are attributed to the strong interactions between the unlike molecules of the mixtures. Further theoretical values of sound velocity in the mixtures have been evaluated using various theories and compared with experimental sound velocities to verify the applicability of such theories to the systems studied. Theoretical ultrasonic velocity data has been used to study molecular interactions in the systems investigated.

  9. 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.

  10. 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.

  11. 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 ...

  12. Aerogel as a Soft Acoustic Metamaterial for Airborne Sound

    Science.gov (United States)

    Guild, Matthew D.; García-Chocano, Victor M.; Sánchez-Dehesa, José; Martin, Theodore P.; Calvo, David C.; Orris, Gregory J.

    2016-03-01

    Soft acoustic metamaterials utilizing mesoporous structures have been proposed recently as a means for tuning the overall effective properties of the metamaterial and providing better coupling to the surrounding air. In this paper, the use of silica aerogel is examined theoretically and experimentally as part of a compact soft acoustic metamaterial structure, which enables a wide range of exotic effective macroscopic properties to be demonstrated, including negative density, density near zero, and nonresonant broadband slow-sound propagation. Experimental data are obtained on the effective density and sound speed using an air-filled acoustic impedance tube for flexural metamaterial elements, which have been investigated previously only indirectly due to the large contrast in acoustic impedance compared to that of air. Experimental results are presented for silica aerogel arranged in parallel with either one or two acoustic ports and are in very good agreement with the theoretical model.

  13. 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...

  14. 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.

  15. 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.

  16. Acoustic logic gates and Boolean operation based on self-collimating acoustic beams

    Science.gov (United States)

    Zhang, Ting; Cheng, Ying; Guo, Jian-zhong; Xu, Jian-yi; Liu, Xiao-jun

    2015-03-01

    The reveal of self-collimation effect in two-dimensional (2D) photonic or acoustic crystals has opened up possibilities for signal manipulation. In this paper, we have proposed acoustic logic gates based on the linear interference of self-collimated beams in 2D sonic crystals (SCs) with line-defects. The line defects on the diagonal of the 2D square SCs are actually functioning as a 3 dB splitter. By adjusting the phase difference between two input signals, the basic Boolean logic functions such as XOR, OR, AND, and NOT are achieved both theoretically and experimentally. Due to the non-diffracting property of self-collimation beams, more complex Boolean logic and algorithms such as NAND, NOR, and XNOR can be realized by cascading the basic logic gates. The achievement of acoustic logic gates and Boolean operation provides a promising approach for acoustic signal computing and manipulations.

  17. Acoustic logic gates and Boolean operation based on self-collimating acoustic beams

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ting; Xu, Jian-yi [Key Laboratory of Modern Acoustics, Department of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Cheng, Ying, E-mail: chengying@nju.edu.cn; Liu, Xiao-jun, E-mail: liuxiaojun@nju.edu.cn [Key Laboratory of Modern Acoustics, Department of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China); Guo, Jian-zhong [School of Physics and Information Technology, Shaanxi Normal University, Xian 710119 (China)

    2015-03-16

    The reveal of self-collimation effect in two-dimensional (2D) photonic or acoustic crystals has opened up possibilities for signal manipulation. In this paper, we have proposed acoustic logic gates based on the linear interference of self-collimated beams in 2D sonic crystals (SCs) with line-defects. The line defects on the diagonal of the 2D square SCs are actually functioning as a 3 dB splitter. By adjusting the phase difference between two input signals, the basic Boolean logic functions such as XOR, OR, AND, and NOT are achieved both theoretically and experimentally. Due to the non-diffracting property of self-collimation beams, more complex Boolean logic and algorithms such as NAND, NOR, and XNOR can be realized by cascading the basic logic gates. The achievement of acoustic logic gates and Boolean operation provides a promising approach for acoustic signal computing and manipulations.

  18. Magnetic resonance imaging of acoustic streaming: absorption coefficient and acoustic field shape estimation.

    Science.gov (United States)

    Madelin, Guillaume; Grucker, Daniel; Franconi, Jean-Michel; Thiaudiere, Eric

    2006-07-01

    In this study, magnetic resonance imaging (MRI) is used to visualize acoustic streaming in liquids. A single-shot spin echo sequence (HASTE) with a saturation band perpendicular to the acoustic beam permits the acquisition of an instantaneous image of the flow due to the application of ultrasound. An average acoustic streaming velocity can be estimated from the MR images, from which the ultrasonic absorption coefficient and the bulk viscosity of different glycerol-water mixtures can be deduced. In the same way, this MRI method could be used to assess the acoustic field and time-average power of ultrasonic transducers in water (or other liquids with known physical properties), after calibration of a geometrical parameter that is dependent on the experimental setup.

  19. Application of Gauge Theory to Acoustic Fields -- Revolutionizing and Rewriting the Whole Field of Acoustics

    Science.gov (United States)

    Gan, W. S.

    2008-12-01

    This paper is to be dedicated to Prof C N Yang's 85th birthday celebration because the idea here was inspired by Prof Yang's public lecture in Singapore in 2006. There are many similarities between electromagnetic waves and acoustic waves. Maxwell's equations for em waves is the oldest gauge theory. We discover symmetries in the pair of wave equations in the acoustic stress field and the velocity field. We also derive a new equation in terms of the stress field for sound propagation in solids. This is different from the Christoffel's equation which is in term of the velocity field. We feel that stress field can better characterize the elastic properties of the sound waves. We also derive the acoustic gauge field condition and gauge invariance and symmetries for the acoustic fields. We also apply symmetries to study negative refraction. Note from Publisher: This article contains the abstract only.

  20. 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...

  1. 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.

  2. 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.

  3. 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.

  4. 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...

  5. 环氧树脂基轻质芯材夹层复合吸声结构的水声性能%Underwater Acoustic Properties of Sound Absorption Structure of Sandwich Composites Based on Light Epoxy Resin Core Material

    Institute of Scientific and Technical Information of China (English)

    李浩; 梅志远; 朱锡

    2011-01-01

    Sound absorption structure of light sandwich composite based on epoxy resin (EPS) was synthesized from glass fiber, vinyl ester resins, epoxy resin, hollow glass microsphere. The underwater acoustical properties of EPS specimen were measured in the sound pulse tube and anechoic tank. The experiment results indicate that underwater acoustic properties of EPS are affected by the technological parameters of core material such as proportion of matrix, content of polyether amine curing agent and proportion of upper and lower layer. The underwater sound absorption coefficient of EPS is not less than 0.5 at 5 kHz ~ 30 kHz with the relative density 0.8 + 0.05 and thickness 25 mm of core material by regulating the technological parameters. EPS has a low density and excellent underwater sound stealth properties. The application range of sound absorption structure of sandwich composite will be enlarged. Then, sound absorption mechanism of EPS was analyzed.%用玻璃纤维、乙烯基树脂、环氧树脂和空心玻璃微珠等为原料合成了环氧树脂基轻质夹层复合吸声结构(EPS),在脉冲声管和消声水池中测试了EPS试件的反射系数和吸声系数,测试结果表明,EPS的水声性能受到芯材基体比例、聚醚胺固化剂含量及分层比例等工艺参数的影响,通过合理控制这些参数,可以使芯材相对密度0.8±0.05、厚度25 mm的EPS在5kHz~30kHz频段内平均吸声系数不低于0.5,具有质轻和良好的水下声隐身能力,扩大了夹层复合吸声结构的使用范围.最后对EPS的吸声机理进行了分析.

  6. Absorption of surface acoustic waves by graphene

    Directory of Open Access Journals (Sweden)

    S. H. Zhang

    2011-06-01

    Full Text Available We present a theoretical study on interactions of electrons in graphene with surface acoustic waves (SAWs. We find that owing to momentum and energy conservation laws, the electronic transition accompanied by the SAW absorption cannot be achieved via inter-band transition channels in graphene. For graphene, strong absorption of SAWs can be observed in a wide frequency range up to terahertz at room temperature. The intensity of SAW absorption by graphene depends strongly on temperature and can be adjusted by changing the carrier density. This study is relevant to the exploration of the acoustic properties of graphene and to the application of graphene as frequency-tunable SAW devices.

  7. Broadband enhanced transmission of acoustic waves through serrated metal gratings

    Science.gov (United States)

    Qi, Dong-Xiang; Fan, Ren-Hao; Deng, Yu-Qiang; Peng, Ru-Wen; Wang, Mu; Jiangnan University Collaboration

    In this talk, we present our studies on broadband properties of acoustic waves through metal gratings. We have demonstrated that serrated metal gratings, which introduce gradient coatings, can give rise to broadband transmission enhancement of acoustic waves. Here, we have experimentally and theoretically studied the acoustic transmission properties of metal gratings with or without serrated boundaries. The average transmission is obviously enhanced for serrated metal gratings within a wide frequency range, while the Fabry-Perot resonance is significantly suppressed. An effective medium hypothesis with varying acoustic impedance is proposed to analyze the mechanism, which was verified through comparison with finite-element simulation. The serrated boundary supplies gradient mass distribution and gradient normal acoustic impedance, which could efficiently reduce the boundary reflection. Further, by increasing the region of the serrated boundary, we present a broadband high-transmission grating for wide range of incident angle. Our results may have potential applications to broadband acoustic imaging, acoustic sensing and new acoustic devices. References: [1] Dong-Xiang Qi, Yu-Qiang Deng, Di-Hu Xu, Ren-Hao Fan, Ru-Wen Peng, Ze-Guo Chen, Ming-Hui Lu, X. R. Huang and Mu Wang, Appl. Phys. Lett. 106, 011906 (2015); [2] Dong-Xiang Qi, Ren-Hao Fan, Ru-Wen Peng, Xian-Rong Huang, Ming-Hui Lu, Xu Ni, Qing Hu, and Mu Wang, Applied Physics Letters 101, 061912 (2012).

  8. On three-dimensional spherical acoustic cloaking

    Energy Technology Data Exchange (ETDEWEB)

    Munteanu, Ligia; Chiroiu, Veturia, E-mail: ligia_munteanu@hotmail.com, E-mail: veturiachiroiu@yahoo.com [Institute of Solid Mechanics, Romanian Academy, 15 Constantin Mille, PO Box 1-863, 010141 Bucharest (Romania)

    2011-08-15

    Transformation acoustics opens a new avenue towards the design of acoustic metamaterials, which are materials engineered at the subwavelength scale in order to mimic the parameters in wave equations. The design of the acoustic cloaking is based on the property of equations being invariant under a coordinate transformation, i.e. a specific spatial compression is equivalent to a variation of the material parameters in the original space. In this paper, the sound invisibility performance is discussed for spherical cloaks. The original domain consists of alternating concentric layers made from piezoelectric ceramics and epoxy resin, following a triadic Cantor sequence. The spatial compression, obtained by applying the concave-down transformation, leads to an equivalent domain with an inhomogeneous and anisotropic distribution of the material parameters.

  9. Constructing acoustic timefronts using random matrix theory

    CERN Document Server

    Hegewisch, Katherine C

    2012-01-01

    In a recent letter [Europhys. Lett. {\\bf 97}, 34002 (2012)], random matrix theory is introduced for long-range acoustic propagation in the ocean. The theory is expressed in terms of unitary propagation matrices that represent the scattering between acoustic modes due to sound speed fluctuations induced by the ocean's internal waves. The scattering exhibits a power-law decay as a function of the differences in mode numbers thereby generating a power-law, banded, random unitary matrix ensemble. This work gives a more complete account of that approach and extends the methods to the construction of an ensemble of acoustic timefronts. The result is a very efficient method for studying the statistical properties of timefronts at various propagation ranges that agrees well with propagation based on the parabolic equation. It helps identify which information about the ocean environment survives in the timefronts and how to connect features of the data to the surviving environmental information. It also makes direct c...

  10. Broad-band acoustic hyperbolic metamaterial

    CERN Document Server

    Shen, Chen; Sui, Ni; Wang, Wenqi; Cummer, Steven A; Jing, Yun

    2015-01-01

    Acoustic metamaterials (AMMs) are engineered materials, made from subwavelength structures, that exhibit useful or unusual constitutive properties. There has been intense research interest in AMMs since its first realization in 2000 by Liu et al. A number of functionalities and applications have been proposed and achieved using AMMs. Hyperbolic metamaterials are one of the most important types of metamaterials due to their extreme anisotropy and numerous possible applications, including negative refraction, backward waves, spatial filtering, and subwavelength imaging. Although the importance of acoustic hyperbolic metamaterials (AHMMs) as a tool for achieving full control of acoustic waves is substantial, the realization of a broad-band and truly hyperbolic AMM has not been reported so far. Here, we demonstrate the design and experimental characterization of a broadband AHMM that operates between 1.0 kHz and 2.5 kHz.

  11. Acoustic Resonance Characteristics of Rock and Concrete Containing Fractures

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, Seiji [Univ. of California, Berkeley, CA (United States)

    1998-08-01

    In recent years, acoustic resonance has drawn great attention as a quantitative tool for characterizing properties of materials and detecting defects in both engineering and geological materials. In quasi-brittle materials such as rock and concrete, inherent fractures have a significant influence on their mechanical and hydraulic properties. Most of these fractures are partially open, providing internal boundaries that are visible to propagating seismic waves. Acoustic resonance occurs as a result of constructive and destructive interferences of propagating waves. Therefore the geometrical and mechanical properties of the fracture are also interrogated by the acoustic resonance characteristics of materials. The objective of this dissertation is to understand the acoustic resonance characteristics of fractured rock and concrete.

  12. Doping effects of CuO additives on the properties of low-temperature-sintered PMnN-PZT-based piezoelectric ceramics and their applications on surface acoustic wave devices.

    Science.gov (United States)

    Tsai, Cheng-Che; Chu, Sheng-Yuan; Lu, Chun-Hsien

    2009-03-01

    To develop the anisotropic ceramic substrate with low sintering temperature for surface acoustic wave (SAW) applications, the low cost and feasible material with moderate piezoelectric properties, good dielectric properties, and higher Curie temperature were explored. The piezoelectric ceramics with compositions of Pb[(Mn(1/3)Nb(2/3))(0.06-) (Zr(0.52)Ti(0.48))0.94] O(3) (PMnN-PZT) + 0.5 wt.% PbO + x wt.% CuO (0.05 = x = 0.3) had been prepared by the conventional mixed-oxides method. CuO dopants were used as the sintering aid to improve the bulk density under low sintering temperature (i.e., 980-1040 degrees C). The phase structures, microstructures, frequency behavior of dielectric properties (up to 50 MHz), piezoelectric properties, ferroelectric properties, and temperature stability with the amount of CuO additive were systematically investigated. Experimental results showed that the sintering temperature could be lowered down to 1020 degrees C and still keep reasonably good piezoelectric activity (i.e., high electromechanical coupling factor (k(p)), (k(t)) and dielectric and ferroelectric properties. The preferable composition, obtained at x = 0.1, presented the values of the electromechanical coupling factor (k(p)) (k(t)), mechanical quality factor (Q(m)), piezoelectric charge constant (d(33)), dielectric constant, dielectric loss, temperature coefficient of resonant frequency (TCF(B)), and Curie point (T(c)) of 0.54, 0.48, 850, 238 pc/N, 1450, 0.0023, 1.1 kV/mm, 26 coul/cm(2), -150 ppm/ degrees C, and 348 degrees C. Using this developed low-temperature-sintered material to make the piezoelectric substrate, the SAW filter was fabricated and its properties were measured. Results showed that this device possessed very high value of k(2)(7.13%) with a good TCF (-40.15 ppm/ degrees C), and a surface wave velocity (V(P)) of 2196 m/s.

  13. 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 ...

  14. 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...

  15. 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 ...

  16. 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.

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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.

  2. 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 ...

  3. 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...

  4. 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 ...

  5. 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.

  6. 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 ...

  7. 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 ...

  8. 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...

  9. 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 ...

  10. Mobile platform for acoustic mine detection applications

    Science.gov (United States)

    Libbey, Brad; Fenneman, Douglas; Burns, Brian

    2005-06-01

    Researchers in academia have successfully demonstrated acoustic landmine detection techniques. These typically employ acoustic or seismic sources to induce vibration in the mine/soil system, and use vibration sensors such as laser vibrometers or geophones to measure the resultant surface motion. These techniques exploit the unique mechanical properties of landmines to discriminate the vibration response of a buried mine from an off-target measurement. The Army requires the ability to rapidly and reliably scan an area for landmines and is developing a mobile platform at NVESD to meet this requirement. The platform represents an initial step toward the implementation of acoustic mine detection technology on a representative field vehicle. The effort relies heavily on the acoustic mine detection cart system developed by researchers at the University of Mississippi and Planning Systems, Inc. The NVESD platform consists of a John Deere E-gator configured with a robotic control system to accurately position the vehicle. In its present design, the E-gator has been outfitted with an array of laser vibrometers and a bank of loudspeakers. Care has been taken to ensure that the vehicle"s mounting hardware and data acquisition algorithms are sufficiently robust to accommodate the implementation of other sensor modalities. A thorough discussion of the mobile platform from its inception to its present configuration will be provided. Specific topics to be addressed include the vehicle"s control and data acquisition systems. Preliminary results from acoustic mine detection experiments will also be presented.

  11. Magnetic resonance acoustic radiation force imaging.

    Science.gov (United States)

    McDannold, Nathan; Maier, Stephan E

    2008-08-01

    Acoustic radiation force impulse imaging is an elastography method developed for ultrasound imaging that maps displacements produced by focused ultrasound pulses systematically applied to different locations. The resulting images are "stiffness weighted" and yield information about local mechanical tissue properties. Here, the feasibility of magnetic resonance acoustic radiation force imaging (MR-ARFI) was tested. Quasistatic MR elastography was used to measure focal displacements using a one-dimensional MRI pulse sequence. A 1.63 or 1.5 MHz transducer supplied ultrasound pulses which were triggered by the magnetic resonance imaging hardware to occur before a displacement-encoding gradient. Displacements in and around the focus were mapped in a tissue-mimicking phantom and in an ex vivo bovine kidney. They were readily observed and increased linearly with acoustic power in the phantom (R2=0.99). At higher acoustic power levels, the displacement substantially increased and was associated with irreversible changes in the phantom. At these levels, transverse displacement components could also be detected. Displacements in the kidney were also observed and increased after thermal ablation. While the measurements need validation, the authors have demonstrated the feasibility of detecting small displacements induced by low-power ultrasound pulses using an efficient magnetic resonance imaging pulse sequence that is compatible with tracking of a dynamically steered ultrasound focal spot, and that the displacement increases with acoustic power. MR-ARFI has potential for elastography or to guide ultrasound therapies that use low-power pulsed ultrasound exposures, such as drug delivery.

  12. 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....

  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. 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

  15. Sound reduction by metamaterial-based acoustic enclosure

    Directory of Open Access Journals (Sweden)

    Shanshan Yao

    2014-12-01

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

  16. 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.

  17. Dual-enhanced photothermal conversion properties of reduced graphene oxide-coated gold superparticles for light-triggered acoustic and thermal theranostics.

    Science.gov (United States)

    Lin, Li-Sen; Yang, Xiangyu; Niu, Gang; Song, Jibin; Yang, Huang-Hao; Chen, Xiaoyuan

    2016-01-28

    A rational design of highly efficient photothermal agents that possess excellent light-to-heat conversion properties is a fascinating topic in nanotheranostics. Herein, we present a facile route to fabricate size-tunable reduced graphene oxide (rGO)-coated gold superparticles (rGO-GSPs) and demonstrate their dual-enhanced photothermal conversion properties for photoacoustic imaging and photothermal therapy. For the first time, graphene oxide (GO) was directly used as an emulsifying agent for the preparation of gold superparticles (GSPs) with near-infrared absorption by the emulsion method. Moreover, GO spontaneously deposited on the surface of GSPs could also act as the precursor of the rGO shell. Importantly, both the plasmonic coupling of the self-assembled gold nanoparticles and the interaction between GSPs and rGO endow rGO-GSPs with enhanced photothermal conversion properties, allowing rGO-GSPs to be used for sensitive photoacoustic detection and efficient photothermal ablation of tumours in vivo. This study provides a facile approach to prepare colloidal superparticles-graphene hybrid nanostructures and will pave the way toward the design and optimization of photothermal nanomaterials with improved properties for theranostic applications.

  18. The Acoustic Performance of Plane Laggings and Similar Multi-Layer Acoustic Structures.

    Science.gov (United States)

    Au, Chak Kuen

    Acoustic laggings are used to inhibit the transmission of the sound radiated from the vibrating surfaces of machines, ducts, pipes, etc. They are formed of layers of porous materials such as fibreglass or mineral wool, layers of impervious materials such as metal cladding sheets and sometimes airspaces. A novel procedure for estimating the diffuse field 1/3 octave band insertion loss which a plane acoustic lagging produces when applied to a plane structure is developed. This novel procedure, which constitutes the major contribution of the work described in the thesis to new knowledge, is based on sets of formulae which describe how obliquely incident plane sound waves interact with the different basic layers, such as the porous layers and the impervious layers which form the lagging. The validity of the procedure is demonstrated by comparing the results it produces with measured results. The procedure is then used to undertake a parametric study to assess the effect of the properties of the various types of layers. Often the cladding sheet of a lagging is fastened to the base structure which is being lagged and an approximate analysis to consider the effect of such fastening is presented. The influence of corrugated cladding sheets is also considered. The principles used to predict the performance of plane acoustic laggings can be adapted to predict other acoustic properties such as the acoustic absorption of plane acoustic structures and this is done in the final part of the thesis. A comparison is made between the predicted and the measured performances of various types of acoustic structures.

  19. Acoustic solitons: A robust tool to investigate the generation and detection of ultrafast acoustic waves

    Science.gov (United States)

    Péronne, Emmanuel; Chuecos, Nicolas; Thevenard, Laura; Perrin, Bernard

    2017-02-01

    Solitons are self-preserving traveling waves of great interest in nonlinear physics but hard to observe experimentally. In this report an experimental setup is designed to observe and characterize acoustic solitons in a GaAs(001) substrate. It is based on careful temperature control of the sample and an interferometric detection scheme. Ultrashort acoustic solitons, such as the one predicted by the Korteweg-de Vries equation, are observed and fully characterized. Their particlelike nature is clearly evidenced and their unique properties are thoroughly checked. The spatial averaging of the soliton wave front is shown to account for the differences between the theoretical and experimental soliton profile. It appears that ultrafast acoustic experiments provide a precise measurement of the soliton velocity. It allows for absolute calibration of the setup as well as the response function analysis of the detection layer. Moreover, the temporal distribution of the solitons is also analyzed with the help of the inverse scattering method. It shows how the initial acoustic pulse profile which gives birth to solitons after nonlinear propagation can be retrieved. Such investigations provide a new tool to probe transient properties of highly excited matter through the study of the emitted acoustic pulse after laser excitation.

  20. 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...

  1. 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.

  2. Acoustic resonances in cylinder bundles oscillating in a compressibile fluid

    Energy Technology Data Exchange (ETDEWEB)

    Lin, W.H.; Raptis, A.C.

    1984-12-01

    This paper deals with an analytical study on acoustic resonances of elastic oscillations of a group of parallel, circular, thin cylinders in an unbounded volume of barotropic, compressible, inviscid fluid. The perturbed motion of the fluid is assumed due entirely to the flexural oscillations of the cylinders. The motion of the fluid disturbances is first formulated in a three-dimensional wave form and then casted into a two-dimensional Helmholtz equation for the harmonic motion in time and in axial space. The acoustic motion in the fluid and the elastic motion in the cylinders are solved simultaneously. Acoustic resonances were approximately determined from the secular (eigenvalue) equation by the method of successive iteration with the use of digital computers for a given set of the fluid properties and the cylinders' geometry and properties. Effects of the flexural wavenumber and the configuration of and the spacing between the cylinders on the acoustic resonances were thoroughly investigated.

  3. The acoustics of aircraft engine-duct systems

    Science.gov (United States)

    Nayfeh, A. H.; Kaiser, J. E.; Telionis, D. P.

    1973-01-01

    Noise generated in aircraft engines is usually suppressed by acoustically treating the engine ducts. The optimization of this treatment requires an understanding of the transmission and attenuation of the acoustic waves. A critical review is presented of the state of the art regarding methods of determining the transmission and attenuation parameters and the effect on these parameters of (1) acoustic properties of liners, (2) the mean velocity, including uniform and shear profiles and nonparallel flow, (3) axial and transverse temperature gradients, (4) slowly and abruptly varying cross sections, and (5) finite-amplitude waves and nonlinear duct liners.

  4. Metamaterial based embedded acoustic filters for structural applications

    Directory of Open Access Journals (Sweden)

    Hongfei Zhu

    2013-09-01

    Full Text Available We investigate the use of acoustic metamaterials to design structural materials with frequency selective characteristics. By exploiting the properties of acoustic metamaterials, we tailor the propagation characteristics of the host structure to effectively filter the constitutive harmonics of an incoming broadband excitation. The design approach exploits the characteristics of acoustic waveguides coupled by cavity modes. By properly designing the cavity we can tune the corresponding resonant mode and, therefore, coupling the waveguide at a prescribed frequency. This structural design can open new directions to develop broadband passive vibrations and noise control systems fully integrated in structural components.

  5. Low Bandwidth Vocoding using EM Sensor and Acoustic Signal Processing

    Energy Technology Data Exchange (ETDEWEB)

    Ng, L C; Holzrichter, J F; Larson, P E

    2001-10-25

    Low-power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference [1]. By combining these data with the corresponding acoustic signal, we've demonstrated an almost 10-fold bandwidth reduction in speech compression, compared to a standard 2.4 kbps LPC10 protocol used in the STU-III (Secure Terminal Unit, third generation) telephone. This paper describes a potential EM sensor/acoustic based vocoder implementation.

  6. Speaker verification using combined acoustic and EM sensor signal processing

    Energy Technology Data Exchange (ETDEWEB)

    Ng, L C; Gable, T J; Holzrichter, J F

    2000-11-10

    Low Power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference. This greatly enhances the quality and quantity of information for many speech related applications. See Holzrichter, Burnett, Ng, and Lea, J. Acoustic. SOC. Am . 103 ( 1) 622 (1998). By combining the Glottal-EM-Sensor (GEMS) with the Acoustic-signals, we've demonstrated an almost 10 fold reduction in error rates from a speaker verification system experiment under a moderate noisy environment (-10dB).

  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 transparency and opacity using Fano Interferences in Metamaterials

    KAUST Repository

    Khelif, A.

    2015-08-04

    We investigate both experimentally and theoretically how to generate the acoustical analogue of the Electromagnetically Induced Transparency. This phenomenon arises from Fano resonances originating from constructive and destructive interferences of a narrow discrete resonance with a broad spectral line or continuum. Measurements were realized on a double-cavity structure by using a Kundt’s Tube. Transmission properties reveal an asymmetric lineshape of the transmission that leads to acoustic transparency.

  11. 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.

  12. 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.

  13. 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.

  14. 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...

  15. 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.

  16. Acoustic and Vibration Control for an Underwater Structure under Mechanical Excitation

    Directory of Open Access Journals (Sweden)

    Shi-Jian Zhu

    2014-01-01

    Full Text Available Acoustic and vibration control for an underwater structure under mechanical excitation has been investigated by using negative feedback control algorithm. The underwater structure is modeled with cylindrical shells, conical shells, and circular bulkheads, of which the motion equations are built with the variational approach, respectively. Acoustic property is analyzed by the Helmholtz integration formulation with boundary element method. Based on negative feedback control algorithm, a control loop with a coupling use of piezoelectric sensor and actuator is built, and accordingly some numerical examples are carried out on active control of structural vibration and acoustic response. Effects of geometrical and material parameters on acoustic and vibration properties are investigated and discussed.

  17. 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

  18. Voice Register in Mon: Acoustics and Electroglottography.

    Science.gov (United States)

    Abramson, Arthur S; Tiede, Mark K; Luangthongkum, Theraphan

    2015-01-01

    Mon is spoken in villages in Thailand and Myanmar. The dialect of Ban Nakhonchum, Thailand, has 2 voice registers, modal and breathy; these phonation types, along with other phonetic properties, distinguish minimal pairs. Four native speakers of this dialect recorded repetitions of 14 randomized words (7 minimal pairs) for acoustic analysis. We used a subset of these pairs in a listening test to verify the perceptual robustness of the register distinction. Acoustic analysis found significant differences in noise component, spectral slope and fundamental frequency. In a subsequent session 4 speakers were also recorded using electroglottography, which showed systematic differences in the contact quotient. The salience of these properties in maintaining the register distinction is discussed in the context of possible tonogenesis for this language. © 2015 S. Karger AG, Basel.

  19. 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...

  20. 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.

  1. 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.

  2. 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.

  3. A new acoustic lens material for large area detectors in photoacoustic breast tomography

    CERN Document Server

    Xia, Wenfeng; van Hespen, Johan C G; Steenbergen, Wiendelt; Manohar, Srirang

    2013-01-01

    Acoustic lenses made of acrylic plastic (PMMA) have been used to enlarge the acceptance angle of sensitive large surface area detectors and improve lateral resolution. However, PMMA lenses introduce image artifacts due to ultrasound internal reflections within the lenses. In this work we investigated this issue proposing a new lens material Stycast 1090SI. We characterized the acoustic properties of the proposed material in comparison with PMMA. Detector performance using negative lenses with the two materials, was tested using finite element simulation and experiment. Further the image quality of a photoacoustic tomography system was studied using k-Wave simulation and experiment. Our acoustic characterization showed that Stycast 1090SI has tissue-like acoustic impedance, high speed of sound and low acoustic attenuation. Both acoustic lenses show significant enlargement of detector acceptance angle and lateral resolution improvement. However, image artifacts induced by acoustic lenses are reduced using the p...

  4. Measurement of stiffness of standing trees and felled logs using acoustics: A review.

    Science.gov (United States)

    Legg, Mathew; Bradley, Stuart

    2016-02-01

    This paper provides a review on the use of acoustics to measure stiffness of standing trees, stems, and logs. An outline is given of the properties of wood and how these are related to stiffness and acoustic velocity throughout the tree. Factors are described that influence the speed of sound in wood, including the different types of acoustic waves which propagate in tree stems and lumber. Acoustic tools and techniques that have been used to measure the stiffness of wood are reviewed. The reasons for a systematic difference between direct and acoustic measurements of stiffness for standing trees, and methods for correction, are discussed. Other techniques, which have been used in addition to acoustics to try to improve stiffness measurements, are also briefly described. Also reviewed are studies which have used acoustic tools to investigate factors that influence the stiffness of trees. These factors include different silvicultural practices, geographic and environmental conditions, and genetics.

  5. Acoustic metamaterial absorbers based on multilayered sonic crystals

    Science.gov (United States)

    Guild, Matthew D.; García-Chocano, Victor M.; Kan, Weiwei; Sánchez-Dehesa, José

    2015-03-01

    Through the use of a layered arrangement, it is shown that lossy sonic crystals can be arranged to create a structure with extreme acoustic properties, namely, an acoustic metamaterial. This artificial structure shows different effective fluids and absorptive properties in different orientations. Theoretical, numerical, and experimental results examining thermoviscous losses in sonic crystals are presented, enabling the fabrication and characterization of an acoustic metamaterial absorber with complex-valued anisotropic inertia. To accurately describe and fabricate such an acoustic metamaterial in a realizable experimental configuration, confining structures are needed which modify the effective properties, due to the thermal and viscous boundary layer effects within the sonic crystal lattice. Theoretical formulations are presented which describe the effects of these confined sonic crystals, both individually and as part of an acoustic metamaterial structure. Experimental demonstrations are also reported using an acoustic impedance tube. The formulations developed can be written with no unknown or empirical coefficients, due to the structured lattice of the sonic crystals and organized layering scheme; and it is shown that higher filling fraction arrangements can be used to provide a large enhancement in the loss factor.

  6. Design, characterization and modeling of biobased acoustic foams

    Science.gov (United States)

    Ghaffari Mosanenzadeh, Shahrzad

    Polymeric open cell foams are widely used as sound absorbers in sectors such as automobile, aerospace, transportation and building industries, yet there is a need to improve sound absorption of these foams through understanding the relation between cell morphology and acoustic properties of porous material. Due to complicated microscopic structure of open cell foams, investigating the relation between foam morphology and acoustic properties is rather intricate and still an open problem in the field. The focus of this research is to design and develop biobased open cell foams for acoustic applications to replace conventional petrochemical based foams as well as investigating the link between cell morphology and macroscopic properties of open cell porous structures. To achieve these objectives, two industrially produced biomaterials, polylactide (PLA) and polyhydroxyalkanoate (PHA) and their composites were examined and highly porous biobased foams were fabricated by particulate leaching and compression molding. Acoustic absorption capability of these foams was enhanced utilizing the effect of co-continuous blends to form a bimodal porous structure. To tailor mechanical and acoustic properties of biobased foams, blends of PLA and PHA were studied to reach the desired mechanical and viscoelastic properties. To enhance acoustic properties of porous medium for having a broad band absorption effect, cell structure must be appropriately graded. Such porous structures with microstructural gradation are called Functionally Graded Materials (FGM). A novel graded foam structure was designed with superior sound absorption to demonstrate the effect of cell arrangement on performance of acoustic fixtures. Acoustic measurements were performed in a two microphone impedance tube and acoustic theory of Johnson-Champoux-Allard was applied to the fabricated foams to determine micro cellular properties such as tortuosity, viscous and thermal lengths from sound absorption impedance tube

  7. Impact of acoustic cavitation on food emulsions.

    Science.gov (United States)

    Krasulya, Olga; Bogush, Vladimir; Trishina, Victoria; Potoroko, Irina; Khmelev, Sergey; Sivashanmugam, Palani; Anandan, Sambandam

    2016-05-01

    The work explores the experimental and theoretical aspects of emulsification capability of ultrasound to deliver stable emulsions of sunflower oil in water and meat sausages. In order to determine optimal parameters for direct ultrasonic emulsification of food emulsions, a model was developed based on the stability of emulsion droplets in acoustic cavitation field. The study is further extended to investigate the ultrasound induced changes to the inherent properties of raw materials under the experimental conditions of sono-emulsification.

  8. 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.

  9. Acoustic and categorical dissimilarity of musical timbre: Evidence from asymmetriesbetween acoustic and chimeric sounds

    Directory of Open Access Journals (Sweden)

    Kai eSiedenburg

    2016-01-01

    Full Text Available This paper investigates the role of acoustic and categorical information in timbre dissimilarity ratings. Using a Gammatone-filterbank-based sound transformation, we created tones that were rated as less familiar than recorded tones from orchestral instruments and that were harder to associate with an unambiguous sound source (Exp. 1. A subset of transformed tones, a set of orchestral recordings, and a mixed set were then rated on pairwise dissimilarity (Exp. 2A. We observed that recorded instrument timbres clustered into subsets that distinguished timbres according to acoustic and categorical properties. For the subset of cross-category comparisons in the mixed set, we observed asymmetries in the distribution of ratings, as well as a stark decay of inter-rater agreement. These effects were replicated in a more robust within-subjects design (Exp. 2B and cannot be explained by acoustic factors alone. We finally introduced a novel model of timbre dissimilarity based on partial least-squares regression that compared the contributions of both acoustic and categorical timbre descriptors. The best model fit (R^2 = .88 was achieved when both types of descriptors were taken into account. These findings are interpreted as evidence for an interplay of acoustic and categorical information in timbre dissimilarity perception.

  10. Acoustic and Categorical Dissimilarity of Musical Timbre: Evidence from Asymmetries Between Acoustic and Chimeric Sounds.

    Science.gov (United States)

    Siedenburg, Kai; Jones-Mollerup, Kiray; McAdams, Stephen

    2015-01-01

    This paper investigates the role of acoustic and categorical information in timbre dissimilarity ratings. Using a Gammatone-filterbank-based sound transformation, we created tones that were rated as less familiar than recorded tones from orchestral instruments and that were harder to associate with an unambiguous sound source (Experiment 1). A subset of transformed tones, a set of orchestral recordings, and a mixed set were then rated on pairwise dissimilarity (Experiment 2A). We observed that recorded instrument timbres clustered into subsets that distinguished timbres according to acoustic and categorical properties. For the subset of cross-category comparisons in the mixed set, we observed asymmetries in the distribution of ratings, as well as a stark decay of inter-rater agreement. These effects were replicated in a more robust within-subjects design (Experiment 2B) and cannot be explained by acoustic factors alone. We finally introduced a novel model of timbre dissimilarity based on partial least-squares regression that compared the contributions of both acoustic and categorical timbre descriptors. The best model fit (R (2) = 0.88) was achieved when both types of descriptors were taken into account. These findings are interpreted as evidence for an interplay of acoustic and categorical information in timbre dissimilarity perception.

  11. Dimensional analysis of acoustically propagated signals

    Science.gov (United States)

    Hansen, Scott D.; Thomson, Dennis W.

    1993-01-01

    Traditionally, long term measurements of atmospherically propagated sound signals have consisted of time series of multiminute averages. Only recently have continuous measurements with temporal resolution corresponding to turbulent time scales been available. With modern digital data acquisition systems we now have the capability to simultaneously record both acoustical and meteorological parameters with sufficient temporal resolution to allow us to examine in detail relationships between fluctuating sound and the meteorological variables, particularly wind and temperature, which locally determine the acoustic refractive index. The atmospheric acoustic propagation medium can be treated as a nonlinear dynamical system, a kind of signal processor whose innards depend on thermodynamic and turbulent processes in the atmosphere. The atmosphere is an inherently nonlinear dynamical system. In fact one simple model of atmospheric convection, the Lorenz system, may well be the most widely studied of all dynamical systems. In this paper we report some results of our having applied methods used to characterize nonlinear dynamical systems to study the characteristics of acoustical signals propagated through the atmosphere. For example, we investigate whether or not it is possible to parameterize signal fluctuations in terms of fractal dimensions. For time series one such parameter is the limit capacity dimension. Nicolis and Nicolis were among the first to use the kind of methods we have to study the properties of low dimension global attractors.

  12. Acoustic tomography in the atmospheric surface layer

    Directory of Open Access Journals (Sweden)

    A. Ziemann

    Full Text Available Acoustic tomography is presented as a technique for remote monitoring of meteorological quantities. This method and a special algorithm of analysis can directly produce area-averaged values of meteorological parameters. As a result consistent data will be obtained for validation of numerical atmospheric micro-scale models. Such a measuring system can complement conventional point measurements over different surfaces. The procedure of acoustic tomography uses the horizontal propagation of sound waves in the atmospheric surface layer. Therefore, to provide a general overview of sound propagation under various atmospheric conditions a two-dimensional ray-tracing model according to a modified version of Snell's law is used. The state of the crossed atmosphere can be estimated from measurements of acoustic travel time between sources and receivers at different points. Derivation of area-averaged values of the sound speed and furthermore of air temperature results from the inversion of travel time values for all acoustic paths. Thereby, the applied straight ray two-dimensional tomographic model using SIRT (simultaneous iterative reconstruction technique is characterised as a method with small computational requirements, satisfactory convergence and stability properties as well as simple handling, especially, during online evaluation.

    Key words. Meteorology and atmospheric dynamics (turbulence; instruments and techniques.

  13. Ab initio study of mechanical and thermo-acoustic properties of tough ceramics: applications to HfO{sub 2} in its cubic and orthorhombic phase

    Energy Technology Data Exchange (ETDEWEB)

    Ponce, C A [Departamento de Fisica, Facultad de Ciencias Exactas, y Naturales y Agrimensura, UNNE, Campus Universitario, Avenida Libertad 5600, CP 3400, Corrientes (Argentina); Casali, R A [Departamento de Fisica, Facultad de Ciencias Exactas, y Naturales y Agrimensura, UNNE, Campus Universitario, Avenida Libertad 5600, CP 3400, Corrientes (Argentina); Caravaca, M A [Departamento de Fisico, Quimica, Facultad de Ingenieria, UNNE, Avenida Las Heras 727, CP 3500, Resistencia (Argentina)

    2008-01-30

    By means of the ab initio all-electron new full-potential linear-muffin-tin orbitals method, calculations were made for elastic constants C{sub 11}, C{sub 12} and C{sub 44} for Si, ZrO{sub 2} and HfO{sub 2} in their cubic phase, and constants C{sub 11}, C{sub 22}, C{sub 33}, C{sub 12}, C{sub 13}, C{sub 23}, C{sub 44}, C{sub 55} and C{sub 66} for HfO{sub 2} in its orthorhombic phase. Using the Voigt and Reuss theory, estimations were made for polycrystals of their bulk, shear and Young moduli, and Poisson coefficients. The speed of elastic wave propagations and Debye temperatures were estimated for polycrystals built from Si and the above mentioned compounds. The semicore 4f{sup 14} electrons should be included in the valence set of Hf atom in this all-electron approach if accurate results for elastic properties under pressures are looked for.

  14. 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...

  15. 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

  16. 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

  17. 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...

  18. 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

  19. 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.

  20. Acoustical topology optimization for Zwicker's loudness model - Application to noise barriers

    DEFF Research Database (Denmark)

    Kook, Junghwan; Koo, Kunmo; Hyun, Jaeyub

    2012-01-01

    Traditionally, the objective of design optimization of an acoustic system is to reduce physical acoustic properties, i.e., sound pressure and power. However, since these parameters are not sufficient to present the relation of physical sound stimulus with human perceptual judgment, physical...... acoustic properties may not represent adequate parameters for optimizing acoustic devices. In this paper, we first present a design method for acoustical topology optimization by considering human's subjective conception of sound. To consider human hearing characteristics. Zwicker's loudness is calculated...... according to DIN45631 (ISO 532B). The main objective of this work is to minimize the main specific loudness of a target critical band rate by optimizing the distribution of the reflecting material in a design domain. The Helmholtz equation is used to model acoustic wave propagation and, it is solved using...

  1. 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.

  2. 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.

  3. Modulational instability of ion-acoustic waves in a warm plasma

    Institute of Scientific and Technical Information of China (English)

    薛具奎; 段文山; 郎和

    2002-01-01

    Using the standard reductive perturbation technique, a nonlinear Schrodinger equation is derived to study themodulational instability of finite-amplitude ion-acoustic waves in a non-magnetized warm plasma. It is found thatthe inclusion of ion temperature in the equation modifies the nature of the ion-acoustic wave stability and the solitonstructures. The effects of ion plasma temperature on the modulational stability and ion-acoustic wave properties areinvestigated in detail.

  4. Acoustic-integrated dynamic MR imaging for a patient with obstructive sleep apnea.

    Science.gov (United States)

    Chen, Yunn-Jy; Shih, Tiffany Ting-Fang; Chang, Yi-Chung; Hsu, Ying-Chieh; Huon, Leh-Kiong; Lo, Men-Tzung; Pham, Van-Truong; Lin, Chen; Wang, Pa-Chun

    2015-12-01

    Obstructive sleep apnea syndrome (OSAS) is caused by multi-level upper airway obstruction. Anatomic changes at the sites of obstruction may modify the physical or acoustic properties of snores. The surgical success of OSA depends upon precise localization of obstructed levels. We present a case of OSAS who received simultaneous dynamic MRI and snore acoustic recordings. The synchronized image and acoustic information successfully characterize the sites of temporal obstruction during sleep-disordered breathing events.

  5. Nonlinear propagation and control of acoustic waves in phononic superlattices

    CERN Document Server

    Jiménez, Noé; Picó, Rubén; García-Raffi, Lluís M; Sánchez-Morcillo, Víctor J

    2015-01-01

    The propagation of intense acoustic waves in a one-dimensional phononic crystal is studied. The medium consists in a structured fluid, formed by a periodic array of fluid layers with alternating linear acoustic properties and quadratic nonlinearity coefficient. The spacing between layers is of the order of the wavelength, therefore Bragg effects such as band-gaps appear. We show that the interplay between strong dispersion and nonlinearity leads to new scenarios of wave propagation. The classical waveform distortion process typical of intense acoustic waves in homogeneous media can be strongly altered when nonlinearly generated harmonics lie inside or close to band gaps. This allows the possibility of engineer a medium in order to get a particular waveform. Examples of this include the design of media with effective (e.g. cubic) nonlinearities, or extremely linear media (where distortion can be cancelled). The presented ideas open a way towards the control of acoustic wave propagation in nonlinear regime.

  6. Property.

    Science.gov (United States)

    Piele, Philip K.

    Chapter 7 of a book on school law, this chapter deals with 1979 cases involving disputes over property. Cases involving taxpayer attempts to prevent the construction of school buildings dominate this year's property chapter, as they did last year's. Yet, paradoxically, there is also a significant increase in cases in which taxpayers tried to…

  7. Flat acoustic lens by acoustic grating with curled slits

    KAUST Repository

    Peng, Pai

    2014-10-01

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

  8. 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.

  9. Acoustic characteristics of clearly spoken English fricatives.

    Science.gov (United States)

    Maniwa, Kazumi; Jongman, Allard; Wade, Travis

    2009-06-01

    Speakers can adopt a speaking style that allows them to be understood more easily in difficult communication situations, but few studies have examined the acoustic properties of clearly produced consonants in detail. This study attempts to characterize the adaptations in the clear production of American English fricatives in a carefully controlled range of communication situations. Ten female and ten male talkers produced fricatives in vowel-fricative-vowel contexts in both a conversational and a clear style that was elicited by means of simulated recognition errors in feedback received from an interactive computer program. Acoustic measurements were taken for spectral, amplitudinal, and temporal properties known to influence fricative recognition. Results illustrate that (1) there were consistent overall style effects, several of which (consonant duration, spectral peak frequency, and spectral moments) were consistent with previous findings and a few (notably consonant-to-vowel intensity ratio) of which were not; (2) specific acoustic modifications in clear productions of fricatives were influenced by the nature of the recognition errors that prompted the productions and were consistent with efforts to emphasize potentially misperceived contrasts both within the English fricative inventory and based on feedback from the simulated listener; and (3) talkers differed widely in the types and magnitude of all modifications.

  10. Probing Cell Deformability via Acoustically Actuated Bubbles.

    Science.gov (United States)

    Xie, Yuliang; Nama, Nitesh; Li, Peng; Mao, Zhangming; Huang, Po-Hsun; Zhao, Chenglong; Costanzo, Francesco; Huang, Tony Jun

    2016-02-17

    An acoustically actuated, bubble-based technique is developed to investigate the deformability of cells suspended in microfluidic devices. A microsized bubble is generated by an optothermal effect near the targeted cells, which are suspended in a microfluidic chamber. Subsequently, acoustic actuation is employed to create localized acoustic streaming. In turn, the streaming flow results in hydrodynamic forces that deform the cells in situ. The deformability of the cells is indicative of their mechanical properties. The method in this study measures mechanical biomarkers from multiple cells in a single experiment, and it can be conveniently integrated with other bioanalysis and drug-screening platforms. Using this technique, the mean deformability of tens of HeLa, HEK, and HUVEC cells is measured to distinguish their mechanical properties. HeLa cells are deformed upon treatment with Cytochalasin. The technique also reveals the deformability of each subpopulation in a mixed, heterogeneous cell sample by the use of both fluorescent markers and mechanical biomarkers. The technique in this study, apart from being relevant to cell biology, will also enable biophysical cellular diagnosis.

  11. 组织声学特性对高强度聚焦超声温度场的影响%Effect of tissue acoustic properties on HIFU temperature field

    Institute of Scientific and Technical Information of China (English)

    张晓静; 张平; 朱元光; 孙武军; 菅喜岐; 李智华

    2010-01-01

    目的 数值仿真组织声学特性对高强度聚焦超声(HIFU)焦域处温度场的影响,为HIFU治疗安全性和可靠性提供理论依据.方法 以实测新鲜离体猪肝组织不同温度下的声速和衰减系数为依据,利用时域有限差分(FDTD)法数值仿真研究HIFU治疗过程中组织内声速、衰减系数的变化和温度场的分布,分析讨论声速和衰减系数变化对60 ℃以上可治疗区域大小、位置的影响.结果 随着照射时间的延长,焦域处肝组织温升增大,声速下降,声衰减系数增大.随着声速的变化,形成的可治疗区域变大,焦点位置向远离换能器方向移动;随着声衰减系数的变化,焦域大小和焦点位置几乎不变.结论 猪肝组织内声速的变化对可治疗焦域的位置和大小影响较大;声衰减系数的变化对焦域的影响较小.%Objective To improve the safety and reliability in high intensity focused ultrasound(HIFU)therapy, the effects of tissue acoustic properties on the high intensity focused ultrasound temperature field were investigated. Methods Based on the measured data of sound velocity and attenuation coefficient at different temperature, the variation of sound velocity and attenuation coefficient, and the temperature distribution in tissue during HIFU therapy was simulated using FDTD method. Moreover, the effects of the two variable acoustic parameters on the therapeutic region above 60 ℃ were evaluated. Results Tissue temperature raise, sound speed decreased and the attenuation coefficient increased in the focal region, along with the passage of the exposure time. Therapeutic region increased slightly and the focal point slightly moved away from the transducer when the sound velocity varied. There were negligible changes in the therapeutic region and the position of focal point when the attenuation coefficient changed alone in the study. Conclusion The variation of sound velocity can affect the size and location of the focal

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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

  1. Wavelet Analysis for Acoustic Phased Array

    Science.gov (United States)

    Kozlov, Inna; Zlotnick, Zvi

    2003-03-01

    Wavelet spectrum analysis is known to be one of the most powerful tools for exploring quasistationary signals. In this paper we use wavelet technique to develop a new Direction Finding (DF) Algorithm for the Acoustic Phased Array (APA) systems. Utilising multi-scale analysis of libraries of wavelets allows us to work with frequency bands instead of individual frequency of an acoustic source. These frequency bands could be regarded as features extracted from quasistationary signals emitted by a noisy object. For detection, tracing and identification of a sound source in a noisy environment we develop smart algorithm. The essential part of this algorithm is a special interacting procedure of the above-mentioned DF-algorithm and the wavelet-based Identification (ID) algorithm developed in [4]. Significant improvement of the basic properties of a receiving APA pattern is achieved.

  2. Acoustic barriers obtained from industrial wastes.

    Science.gov (United States)

    Garcia-Valles, M; Avila, G; Martinez, S; Terradas, R; Nogués, J M

    2008-07-01

    Acoustic pollution is an environmental problem that is becoming increasingly more important in our society. Likewise, the accumulation of generated waste and the need for waste management are also becoming more and more pressing. In this study we describe a new material--called PROUSO--obtained from industrial wastes. PROUSO has a variety of commercial and engineering, as well as building, applications. The main raw materials used for this environmentally friendly material come from slag from the aluminium recycling process, dust from the marble industry, foundry sands, and recycled expanded polystyrene from recycled packaging. Some natural materials, such as plastic clays, are also used. To obtain PROUSO we used a conventional ceramic process, forming new mineral phases and incorporating polluted elements into the structure. Its physical properties make PROUSO an excellent acoustic and thermal insulation material. It absorbs 95% of the sound in the frequency band of the 500 Hz. Its compressive strength makes it ideal for use in ceramic wall building.

  3. Compact acoustic antenna design using labyrinthine metamaterials

    Science.gov (United States)

    Ren, Chunyu

    2015-05-01

    We present an effective design and architecture for a class of acoustic antennas in air. The work begins with a conformal transformation method that yields the preliminary design, which is constructed using an isotropic but inhomogeneous material. However, the desired material parameters have been unavailable until now. Here we show that by scaling up the refractive index and optimizing the geometry in the preliminary design, a series of square antennas can be achieved to exhibit an excellent beam-collimating effect. An important part of our strategy is that the device's thickness and material properties can be tailored easily to greatly facilitate its realization. It is also demonstrated that the proposed antenna can be made very thin and readily implemented using labyrinthine acoustic metamaterials.

  4. Thermally induced acoustic waves in porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Gavrilchenko, Iryna V.; Shulimov, Yuriy G.; Skryshevsky, Valeriy A. [Radiophysics Department, Kyiv National Taras Shevchenko University, Kyiv (Ukraine); Benilov, Arthur I. [Radiophysics Department, Kyiv National Taras Shevchenko University, Kyiv (Ukraine); Laboratoire d' Electronique, Optoelectronique et Microsystemes, Ecole Centrale de Lyon, Ecully (France)

    2009-07-15

    Thermally induced acoustic waves in structures with porous silicon have been studied. Two different schemas of acoustic phenomena recording are compared: in the first one a signal from microphone was measured as function of output frequency, in second one the resistance of porous silicon was measured using Wheatstone bridge. For both methods, the resonance peak is situated in same frequencies depending on difference in thermal properties between porous silicon and c-Si as well as geometry of studied structures. 1.0 kHz shifting of resonance peak in saturated alcohol vapors comparing to ambient air is observed. It can be applied as new transducer for chemical sensors based on porous silicon. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. 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.

  6. 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.

  7. Sputtered SiO2 as low acoustic impedance material for Bragg mirror fabrication in BAW resonators.

    Science.gov (United States)

    Olivares, Jimena; Wegmann, Enrique; Capilla, José; Iborra, Enrique; Clement, Marta; Vergara, Lucía; Aigner, Robert

    2010-01-01

    In this paper we describe the procedure to sputter low acoustic impedance SiO(2) films to be used as a low acoustic impedance layer in Bragg mirrors for BAW resonators. The composition and structure of the material are assessed through infrared absorption spectroscopy. The acoustic properties of the films (mass density and sound velocity) are assessed through X-ray reflectometry and picosecond acoustic spectroscopy. A second measurement of the sound velocity is achieved through the analysis of the longitudinal lambda/2 resonance that appears in these silicon oxide films when used as uppermost layer of an acoustic reflector placed under an AlN-based resonator.

  8. 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.

  9. 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.

  10. A Soft 3D Acoustic Metafluid with Dual-Band Negative Refractive Index.

    Science.gov (United States)

    Raffy, Simon; Mascaro, Benoit; Brunet, Thomas; Mondain-Monval, Olivier; Leng, Jacques

    2016-03-02

    Spherical silica xerogels are efficient acoustic Mie resonators. When these sub-wavelength inclusions are dispersed in a matrix, the final metafluid may display a negative acoustic refractive index upon a set of precise constraints concerning material properties, concentration, size, and dispersity of the inclusions. Because xerogels may sustain both pressure and shear waves, several bands with negative index can be tailored.

  11. Speech intelligibility for normal hearing and hearing-impaired listeners in simulated room acoustic conditions

    DEFF Research Database (Denmark)

    Arweiler, Iris; Dau, Torsten; Poulsen, Torben

    Speech intelligibility depends on many factors such as room acoustics, the acoustical properties and location of the signal and the interferers, and the ability of the (normal and impaired) auditory system to process monaural and binaural sounds. In the present study, the effect of reverberation...... intelligibility and when binaural cues are effective. (Poster). Partly from HEARCOM project....

  12. Imaging of acoustic attenuation and speed of sound maps using photoacoustic measurements

    NARCIS (Netherlands)

    Willemink, G.H.; Manohar, S.; Purwar, Y.; Slump, C.H.; Heijden, van der F.; Leeuwen, van T.G.; McAleavey, S.A.; D'Hooge, J.

    2008-01-01

    Photoacoustic imaging is an upcoming medical imaging modality with the potential of imaging both optical and acoustic properties of objects. We present a measurement system and outline reconstruction methods to image both speed of sound and acoustic attenuation distributions of an object using only

  13. 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

  14. 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

  15. Examination of silicon solar cells by means of the Scanning Laser Acoustic Microscope (SLAM)

    Science.gov (United States)

    Vorres, C.; Yuhas, D. E.

    1981-01-01

    The Scanning Laser Acoustic Microscope produces images of internal structure in materials. The acoustic microscope is an imaging system based upon acoustic rather than electromagnetic waves. Variations in the elastic propertis are primarily responsible for structure visualized in acoustic micrographs. The instrument used in these investigations is the SONOMICROSCOPE 100 which can be operated at ultrasonic frequencies of from 30 MHz to 500 MHz. The examination of the silicon solar cells was made at 100 MHz. Data are presented in the form of photomicrographs.

  16. 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.

  17. 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.

  18. 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.

  19. Acoustic Communications Measurement Systems (ACOMMS)

    Data.gov (United States)

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

  20. 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...

  1. 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...

  2. 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...

  3. Acoustic Properties of a Renovated Building

    Directory of Open Access Journals (Sweden)

    Tomas Januševičius

    2011-02-01

    Full Text Available The article explores the effects of partitions, ceilings and facades on noise insulation in the renovated different buildings. The conducted experiments were aimed at analyzing partitions of 120 mm brick mounted gypsum panels while other walls were 520 mm thick and plastered on both sides. Under natural conditions, sound insulation factors of facades were measured and compared according to comfort classes. The obtained results revealed that thick brick walls of 520 mm insulated the sound of 58 decibels (dB (class B. In contrast, 120 mm brick masonry partition reduced sound only to 48 dB which is class E and agrees with the lowest class of sound insulation. We also calculated the sound insulation factor applying three formulas considering the mass law of sound insulation and comparing it with other previous studies. The paper examines and discusses the findings of the performed calculations and measurements.Article in Lithuanian

  4. Acoustic property measurements in a photoacoustic imager

    NARCIS (Netherlands)

    Willemink, Rene; Manohar, Srirang; Slump, Cornelis H.; van der Heijden, Ferdinand; van Leeuwen, Ton; Depeursinge, C.D.

    2007-01-01

    Photoacoustics is a hybrid imaging technique that combines the contrast available to optical imaging with the resolution that is possessed by ultrasound imaging. The technique is based on generating ultrasound from absorbing structures in tissue using pulsed light. In photoacoustic (PA) computerized

  5. Acoustic properties of ultrasound contrast agents

    NARCIS (Netherlands)

    N. de Jong (Nico)

    1993-01-01

    textabstractSafety of contrast agents is reported in the years after. Both the intracoronary use of sonicated Renografin as well as intravenous use of commercial product as Albunex and Lechovist has been investigated. Thereafter more pathophysiologic studies were performed. Ten Cate described the po

  6. Acoustic property measurements in a photoacoustic imager

    Science.gov (United States)

    Willemink, René G. H.; Manohar, Srirang; Slump, Cornelis H.; van der Heijden, Ferdi; van Leeuwen, Ton

    2007-07-01

    Photoacoustics is a hybrid imaging technique that combines the contrast available to optical imaging with the resolution that is possessed by ultrasound imaging. The technique is based on generating ultrasound from absorbing structures in tissue using pulsed light. In photoacoustic (PA) computerized tomography (CT) imaging, reconstruction of the optical absorption in a subject, is performed for example by filtered backprojection. The backprojection is performed along circular paths in image space instead of along straight lines as in X-ray CT imaging. To achieve this, the speed-of-sound through the subject is usually assumed constant. An unsuitable speed-of-sound can degrade resolution and contrast. We discuss here a method of actually measuring the speed-of- sound distribution using ultrasound transmission through the subject under photoacoustic investigation. This is achieved in a simple approach that does not require any additional ultrasound transmitter. The method uses a passive element (carbon fiber) that is placed in the imager in the path of the illumination which generates ultrasound by the photoacoustic effect and behaves as an ultrasound source. Measuring the time-of-flight of this ultrasound transient by the same detector used for conventional photoacoustics, allows a speed-of-sound image to be reconstructed. This concept is validated on phantoms.

  7. Acoustic property measurements in a photoacoustic imager

    NARCIS (Netherlands)

    Willemink, G.H.; Manohar, S.; Slump, C.H.; Heijden, van der F.; Leeuwen, van T.G.; Depeursinge, C.D.

    2007-01-01

    Photoacoustics is a hybrid imaging technique that combines the contrast available to optical imaging with the resolution that is possessed by ultrasound imaging. The technique is based on generating ultrasound from absorbing structures in tissue using pulsed light. In photoacoustic (PA) computerized

  8. Modeling structural acoustic properties of loudspeaker cabinets

    DEFF Research Database (Denmark)

    Luan, Yu

    that the stiffeners are parallel to the edges of the plate, but simple considerations make it possible to relax this requirement. Whereas the improved smearing technique is well established for stiffened flat panels, there is no similar established technique for doubly curved stiffened shells. In an additional study......In this dissertation, a theoretical/numerical methodology is presented for coarse and fast predictions of cabinet vibrations. The study is focused on vibrations of rib-stiffened panels by improving a smearing technique and employing it into finite element modeling. The computationally efficient...... smearing technique for a cross-stiffened flat thin rectangular plate has been known for many years, but so far the accuracy of predicted natural frequencies has been inadequate. To improve predictions, all stiffeners including the ones neglected in the ordinary smearing technique are taken into account...

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

    Science.gov (United States)

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

    2016-07-01

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

  10. 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...

  11. Acoustic metamaterials with circular sector cavities and programmable densities.

    Science.gov (United States)

    Akl, W; Elsabbagh, A; Baz, A

    2012-10-01

    Considerable interest has been devoted to the development of various classes of acoustic metamaterials that can control the propagation of acoustical wave energy throughout fluid domains. However, all the currently exerted efforts are focused on studying passive metamaterials with fixed material properties. In this paper, the emphasis is placed on the development of a class of composite one-dimensional acoustic metamaterials with effective densities that are programmed to adapt to any prescribed pattern along the metamaterial. The proposed acoustic metamaterial is composed of a periodic arrangement of cell structures, in which each cell consists of a circular sector cavity bounded by actively controlled flexible panels to provide the capability for manipulating the overall effective dynamic density. The theoretical analysis of this class of multilayered composite active acoustic metamaterials (CAAMM) is presented and the theoretical predictions are determined for a cascading array of fluid cavities coupled to flexible piezoelectric active boundaries forming the metamaterial domain with programmable dynamic density. The stiffness of the piezoelectric boundaries is electrically manipulated to control the overall density of the individual cells utilizing the strong coupling with the fluid domain and using direct acoustic pressure feedback. The interaction between the neighboring cells of the composite metamaterial is modeled using a lumped-parameter approach. Numerical examples are presented to demonstrate the performance characteristics of the proposed CAAMM and its potential for generating prescribed spatial and spectral patterns of density variation.

  12. Design of sandwich acoustic window for sonar domes

    Institute of Scientific and Technical Information of China (English)

    YU Mengsa; LI Dongsheng; GONG Li; XU Jian

    2005-01-01

    Aimed at the low noise design of sonar dome in ships, a method has been presented for calculating the sonar self noise of a simplified sonar dome consisting of sandwich acoustic window and parallel acoustic cavity, which is excited by stationary random pressure fluctuation of turbulence boundary layer, using temporal and spatial double Fourier transform and wavenumber-frequency spectrum analysis. After numerically analyzing the influence of geometrical and physical parameters of acoustic window on the sonar self noise, the design method and reasonable parameters for sandwich acoustic window are proposed. The results show that the property of low noise induced by acoustic window of sandwich is dominated by the cut-off effect of longitudinal wave and transverse wave propagating in the visco-elastic layer of sandwich as well as the mismatch effect of impedance. If the thickness, density, Young's modulus and damping factor of plates and visco-elastic layer as well as the sound speed of longitudinal wave and transverse wave in the visco-elastic layer are selected reasonably, the maximum noise reduction of sandwich acoustic window is 6.5 dB greater than that of a single glass fiber reinforced plastic plate.

  13. Sensor development and calibration for acoustic neutrino detection in ice

    CERN Document Server

    Karg, Timo; Laihem, Karim; Semburg, Benjamin; Tosi, Delia

    2009-01-01

    A promising approach to measure the expected low flux of cosmic neutrinos at the highest energies (E > 1 EeV) is acoustic detection. There are different in-situ test installations worldwide in water and ice to measure the acoustic properties of the medium with regard to the feasibility of acoustic neutrino detection. The parameters of interest include attenuation length, sound speed profile, background noise level and transient backgrounds. The South Pole Acoustic Test Setup (SPATS) has been deployed in the upper 500 m of drill holes for the IceCube neutrino observatory at the geographic South Pole. In-situ calibration of sensors under the combined influence of low temperature, high ambient pressure, and ice-sensor acoustic coupling is difficult. We discuss laboratory calibrations in water and ice. Two new laboratory facilities, the Aachen Acoustic Laboratory (AAL) and the Wuppertal Water Tank Test Facility, have been set up. They offer large volumes of bubble free ice (3 m^3) and water (11 m^3) for the devel...

  14. Photoacoustic image reconstruction: material detection and acoustical heterogeneities

    Science.gov (United States)

    Schoeder, S.; Kronbichler, M.; Wall, W. A.

    2017-05-01

    The correct consideration of acoustical heterogeneities in the context of photoacoustic image reconstruction is an open topic. In this publication a physically motivated algorithm is proposed that reconstructs the optical absorption and diffusion coefficients using a gradient-based scheme. The simultaneous reconstruction of both material properties allows for a subsequent material identification and an accordant update of the acoustical material properties. The algorithm is general in terms of illumination scenarios, detection geometries and applications. No prior knowledge on material distributions needs to be provided, only expected materials have to be specified. Numerical experiments are performed to gain insight into the complex inverse problem and to validate the proposed method. Results show that acoustical heterogeneities are correctly detected improving the optical images.

  15. The effect of boundary shape to acoustic parameters

    Science.gov (United States)

    Prawirasasra, M. S.; Sampurna, R.; Suwandi

    2016-11-01

    To design a room in term of acoustic, many variables need to be considered such as volume, acoustic characteristics & surface area of material and also boundary shape. Modifying each variable possibly change the sound field character. To find impact of boundary shape, every needed properties is simulated through acoustic prediction software. The simulation is using three models with different geometry (asymmetry and symmetry) to produce certain objective parameters. By applying just noticeable difference (JND), the effect is considered known. Furthermore, individual perception is needed to gain subjective parameter. The test is using recorded speech that is convoluted with room impulse of each model. The result indicates that 84% of participants could not recognize the speech which is emit from different geometry properties. In contrast, JND value of T30 is exceed 5%. But for D50, every model has JND below 5%.

  16. Quantum ion-acoustic solitary waves in weak relativistic plasma

    Indian Academy of Sciences (India)

    Biswajit Sahu

    2011-06-01

    Small amplitude quantum ion-acoustic solitary waves are studied in an unmagnetized twospecies relativistic quantum plasma system, comprised of electrons and ions. The one-dimensional quantum hydrodynamic model (QHD) is used to obtain a deformed Korteweg–de Vries (dKdV) equation by reductive perturbation method. A linear dispersion relation is also obtained taking into account the relativistic effect. The properties of quantum ion-acoustic solitary waves, obtained from the deformed KdV equation, are studied taking into account the quantum mechanical effects in the weak relativistic limit. It is found that relativistic effects significantly modify the properties of quantum ion-acoustic waves. Also the effect of the quantum parameter on the nature of solitary wave solutions is studied in some detail.

  17. Biodiversity sampling using a global acoustic approach: contrasting sites with microendemics in New Caledonia.

    Directory of Open Access Journals (Sweden)

    Amandine Gasc

    Full Text Available New Caledonia is a Pacific island with a unique biodiversity showing an extreme microendemism. Many species distributions observed on this island are extremely restricted, localized to mountains or rivers making biodiversity evaluation and conservation a difficult task. A rapid biodiversity assessment method based on acoustics was recently proposed. This method could help to document the unique spatial structure observed in New Caledonia. Here, this method was applied in an attempt to reveal differences among three mountain sites (Mandjélia, Koghis and Aoupinié with similar ecological features and species richness level, but with high beta diversity according to different microendemic assemblages. In each site, several local acoustic communities were sampled with audio recorders. An automatic acoustic sampling was run on these three sites for a period of 82 successive days. Acoustic properties of animal communities were analysed without any species identification. A frequency spectral complexity index (NP was used as an estimate of the level of acoustic activity and a frequency spectral dissimilarity index (Df assessed acoustic differences between pairs of recordings. As expected, the index NP did not reveal significant differences in the acoustic activity level between the three sites. However, the acoustic variability estimated by the index Df , could first be explained by changes in the acoustic communities along the 24-hour cycle and second by acoustic dissimilarities between the three sites. The results support the hypothesis that global acoustic analyses can detect acoustic differences between sites with similar species richness and similar ecological context, but with different species assemblages. This study also demonstrates that global acoustic methods applied at broad spatial and temporal scales could help to assess local biodiversity in the challenging context of microendemism. The method could be deployed over large areas, and

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Acoustic bandpass filters employing shaped resonators

    Science.gov (United States)

    Červenka, M.; Bednařík, M.

    2016-11-01

    This work deals with acoustic bandpass filters realized by shaped waveguide-elements inserted between two parts of an acoustic transmission line with generally different characteristic impedance. It is shown that the formation of a wide passband is connected with the eigenfrequency spectrum of the filter element which acts as an acoustic resonator and that the required filter shape substantially depends on whether the filter characteristic impedance is higher or lower than the characteristic impedance of the waveguide. It is further shown that this class of filters can be realized even without the need of different characteristic impedance. A heuristic technique is proposed to design filter shapes with required transmission properties; it is employed for optimization of low-frequency bandpass filters as well as for design of bandpass filters with wide passband surrounded by wide stopbands as it is typical for phononic crystals, however, in this case the arrangement is much simpler as it consists of only one simple-shaped homogeneous element.

  4. Constructing acoustic timefronts using random matrix theory.

    Science.gov (United States)

    Hegewisch, Katherine C; Tomsovic, Steven

    2013-10-01

    In a recent letter [Hegewisch and Tomsovic, Europhys. Lett. 97, 34002 (2012)], random matrix theory is introduced for long-range acoustic propagation in the ocean. The theory is expressed in terms of unitary propagation matrices that represent the scattering between acoustic modes due to sound speed fluctuations induced by the ocean's internal waves. The scattering exhibits a power-law decay as a function of the differences in mode numbers thereby generating a power-law, banded, random unitary matrix ensemble. This work gives a more complete account of that approach and extends the methods to the construction of an ensemble of acoustic timefronts. The result is a very efficient method for studying the statistical properties of timefronts at various propagation ranges that agrees well with propagation based on the parabolic equation. It helps identify which information about the ocean environment can be deduced from the timefronts and how to connect features of the data to that environmental information. It also makes direct connections to methods used in other disordered waveguide contexts where the use of random matrix theory has a multi-decade history.

  5. Acoustics in Halls for Speech and Music

    Science.gov (United States)

    Gade, Anders C.

    This chapter deals specifically with concepts, tools, and architectural variables of importance when designing auditoria for speech and music. The focus will be on cultivating the useful components of the sound in the room rather than on avoiding noise from outside or from installations, which is dealt with in Chap. 11. The chapter starts by presenting the subjective aspects of the room acoustic experience according to consensus at the time of writing. Then follows a description of their objective counterparts, the objective room acoustic parameters, among which the classical reverberation time measure is only one of many, but still of fundamental value. After explanations on how these parameters can be measured and predicted during the design phase, the remainder of the chapter deals with how the acoustic properties can be controlled by the architectural design of auditoria. This is done by presenting the influence of individual design elements as well as brief descriptions of halls designed for specific purposes, such as drama, opera, and symphonic concerts. Finally, some important aspects of loudspeaker installations in auditoria are briefly touched upon.

  6. 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....

  7. 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....

  8. 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.

  9. Acoustic Classification and Optimization for Multi-Modal Rendering of Real-World Scenes.

    Science.gov (United States)

    Schissler, Carl; Loftin, Christian; Manocha, Dinesh

    2017-02-09

    We present a novel algorithm to generate virtual acoustic effects in captured 3D models of real-world scenes for multimodal augmented reality. We leverage recent advances in 3D scene reconstruction in order to automatically compute acoustic material properties. Our technique consists of a two-step procedure that first applies a convolutional neural network (CNN) to estimate the acoustic material properties, including frequency-dependent absorption coefficients, that are used for interactive sound propagation. In the second step, an iterative optimization algorithm is used to adjust the materials determined by the CNN until a virtual acoustic simulation converges to measured acoustic impulse responses. We have applied our algorithm to many reconstructed real-world indoor scenes and evaluated its fidelity for augmented reality applications.

  10. Underwater acoustical properties of a sound absorption structure with light sandwich composite%轻质夹层复合吸声结构的水声性能实验研究

    Institute of Scientific and Technical Information of China (English)

    李浩; 梅志远; 朱锡

    2011-01-01

    夹层复合吸声结构具有很强的可设计性,得到广泛的应用,但以往研究的此夹层结构的吸声芯材存在密度较大的问题.为解决此问题,采用玻璃钢作为表层材料,多种空心玻璃微珠混合填充环氧树脂和聚氨酯改性环氧树脂合成的高分子吸声材料作为芯材,设计一种轻质夹层复合吸声结构.首先研究确定了表层材料的厚度,并制作了脉冲声管测试试件,根据测试结果确定芯材的合成配方,根据此配方制作了消声水池测试试件,在消声水池中测试了其吸声系数和反射系数,最后对该结构的吸声机理进行了分析,结果证明:用空心玻璃微珠填充环氧树脂和聚氨酯改性环氧树脂可以合成低密度高分子吸声材料(相对密度0.8±0.05),用其作为芯材制作的夹层复合吸声结构具有良好的吸声性能,降低夹层结构的整体重量的同时也具有很好的声隐身效果,更有利于工程的应用.%Sound absorption structure with sandwich composite has been extensively used because it is designable.Here, in order to solving the problem that the density of sound absorption core material of previous sandwich composite structures was larger, a kind of sound absorption structure with light sandwich composite was designed.Its surface material was GFRP, and its core material was polymer sound absorption material synthesized with a variety of hollow glass microsphere, epoxy resin and polyurethane- modified epoxy resin.The thickness of the surface GERP material was studied and determined.The underwater acoustical properties of a specimen were measured in form of a sound pulse tube.The synthetic formula of the core material was determined based on the test results of the pulse tube specimen.The sample was prepareD for anechoic tank test.The sound reflection coefficient and sound absorption coefficient of this sample were measured in the anechoic tank.Then, the sound absorption mechanism of the sound

  11. 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.

  12. 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.

  13. 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.

  14. 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...

  15. 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.

  16. [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.

  17. 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...

  18. Vegetation effects on impulsive events in the acoustic signature of fires.

    Science.gov (United States)

    Yedinak, Kara M; Anderson, Michael J; Apostol, Kent G; Smith, Alistair M S

    2017-01-01

    Acoustic impulse events have long been used as diagnostics for discrete phenomena in the natural world, including the detection of meteor impacts and volcanic eruptions. Wildland fires display an array of such acoustic impulse events in the form of crackling noises. Exploratory research into the properties of these impulse events revealed information regarding the specific properties of plant material. Unique acoustic frequency bands in the upper end of the sonic spectrum correlated to changes in vegetation properties. The signature of acoustic impulse events as they relate to plant species and plant water stress, were investigated in controlled laboratory combustion experiments. Correlation in the frequency range of 6.0-15.0 kHz was found for both species and water stress, indicating the possibility that a digital filter may be capable of identifying vegetation properties during wildland fire events.

  19. Evaluation of the impact of the retrofitting solution on the acoustic and thermal performance of floors

    OpenAIRE

    Villanueva Llauradó, Paula; Fernandez Gomez, Jaime Antonio; González Ramos, Francisco José

    2015-01-01

    Building renovation projects deal with many aspects of construction performance, including energetic and acoustic properties, accessibility, and structural reinforcement. Four aspects must be taken into account in building rehabilitation: proportionality, flexibility, no-deterioration and transversality

  20. Environmental acoustics and the evolution of bird song

    NARCIS (Netherlands)

    Brumm, H.; Naguib, M.

    2009-01-01

    Any signal must get from a sender to a receiver if information is to be transmitted. In the case of bird song, the acoustic properties of the habitat may hinder this being achieved. However, birds as senders and receivers have evolved numerous adaptations to overcome the problem of getting the

  1. Modified electron acoustic field and energy applied to observation data

    Energy Technology Data Exchange (ETDEWEB)

    Abdelwahed, H. G., E-mail: hgomaa-eg@yahoo.com, E-mail: hgomaa-eg@mans.edu.eg [College of Science and Humanitarian Studies, Physics Department, Prince Sattam Bin Abdul Aziz University, Alkharj 11942 (Saudi Arabia); Theoretical Physics Research Group, Physics Department, Faculty of Science, Mansoura University, Mansoura 35516 (Egypt); El-Shewy, E. K. [Theoretical Physics Research Group, Physics Department, Faculty of Science, Mansoura University, Mansoura 35516 (Egypt)

    2016-08-15

    Improved electrostatic acoustic field and energy have been debated in vortex trapped hot electrons and fluid of cold electrons with pressure term plasmas. The perturbed higher-order modified-Korteweg-de Vries equation (PhomKdV) has been worked out. The effect of trapping and electron temperatures on the electro-field and energy properties in auroral plasmas has been inspected.

  2. Materials research at Stanford University. [composite materials, crystal structure, acoustics

    Science.gov (United States)

    1975-01-01

    Research activity related to the science of materials is described. The following areas are included: elastic and thermal properties of composite materials, acoustic waves and devices, amorphous materials, crystal structure, synthesis of metal-metal bonds, interactions of solids with solutions, electrochemistry, fatigue damage, superconductivity and molecular physics and phase transition kinetics.

  3. Surface acoustic wave propagation in graphene film

    Energy Technology Data Exchange (ETDEWEB)

    Roshchupkin, Dmitry, E-mail: rochtch@iptm.ru; Plotitcyna, Olga; Matveev, Viktor; Kononenko, Oleg; Emelin, Evgenii; Irzhak, Dmitry [Institute of Microelectronics Technology and High-Purity Materials Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Ortega, Luc [Laboratoire de Physique des Solides, Univ. Paris-Sud, CNRS, UMR 8502, 91405 Orsay Cedex (France); Zizak, Ivo; Erko, Alexei [Institute for Nanometre Optics and Technology, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein Strasse 15, 12489 Berlin (Germany); Tynyshtykbayev, Kurbangali; Insepov, Zinetula [Nazarbayev University Research and Innovation System, 53 Kabanbay Batyr St., Astana 010000 (Kazakhstan)

    2015-09-14

    Surface acoustic wave (SAW) propagation in a graphene film on the surface of piezoelectric crystals was studied at the BESSY II synchrotron radiation source. Talbot effect enabled the visualization of the SAW propagation on the crystal surface with the graphene film in a real time mode, and high-resolution x-ray diffraction permitted the determination of the SAW amplitude in the graphene/piezoelectric crystal system. The influence of the SAW on the electrical properties of the graphene film was examined. It was shown that the changing of the SAW amplitude enables controlling the magnitude and direction of current in graphene film on the surface of piezoelectric crystals.

  4. Surface acoustic wave propagation in graphene film

    Science.gov (United States)

    Roshchupkin, Dmitry; Ortega, Luc; Zizak, Ivo; Plotitcyna, Olga; Matveev, Viktor; Kononenko, Oleg; Emelin, Evgenii; Erko, Alexei; Tynyshtykbayev, Kurbangali; Irzhak, Dmitry; Insepov, Zinetula

    2015-09-01

    Surface acoustic wave (SAW) propagation in a graphene film on the surface of piezoelectric crystals was studied at the BESSY II synchrotron radiation source. Talbot effect enabled the visualization of the SAW propagation on the crystal surface with the graphene film in a real time mode, and high-resolution x-ray diffraction permitted the determination of the SAW amplitude in the graphene/piezoelectric crystal system. The influence of the SAW on the electrical properties of the graphene film was examined. It was shown that the changing of the SAW amplitude enables controlling the magnitude and direction of current in graphene film on the surface of piezoelectric crystals.

  5. Coherent acoustic vibration of metal nanoshells.

    Science.gov (United States)

    Guillon, C; Langot, P; Del Fatti, N; Vallée, F; Kirakosyan, A S; Shahbazyan, T V; Cardinal, T; Treguer, M

    2007-01-01

    Using time-resolved pump-probe spectroscopy, we have performed the first investigation of the vibrational modes of gold nanoshells. The fundamental isotropic mode launched by a femtosecond pump pulse manifests itself in a pronounced time-domain modulation of the differential transmission probed at the frequency of nanoshell surface plasmon resonance. The modulation amplitude is significantly stronger, and the period is longer than that in a gold nanoparticle of the same overall size, in agreement with theoretical calculations. This distinct acoustical signature of nanoshells provides a new and efficient method for identifying these versatile nanostructures and for studying their mechanical and structural properties.

  6. A Green's function method for surface acoustic waves in functionally graded materials.

    Science.gov (United States)

    Matsuda, Osamu; Glorieux, Christ

    2007-06-01

    Acoustic wave propagation in anisotropic media with one-dimensional inhomogeneity is discussed. Using a Green's function approach, the wave equation with inhomogeneous variation of elastic property and mass density is transformed into an integral equation, which is then solved numerically. The method is applied to find the dispersion relation of surface acoustic waves for a medium with continuously or discontinuously varying elastic property and mass density profiles.

  7. Dust-acoustic solitary waves in a dusty plasma with two-temperature nonthermal ions

    Indian Academy of Sciences (India)

    Zhi-Jian Zhou; Hong-Yan Wang; Kai-Biao Zhang

    2012-01-01

    By using reductive perturbation method, the nonlinear propagation of dust-acoustic waves in a dusty plasma (containing a negatively charged dust fluid, Boltzmann distributed electrons and two-temperature nonthermal ions) is investigated. The effects of two-temperature nonthermal ions on the basic properties of small but finite amplitude nonlinear dust-acoustic waves are examined. It is found that two-temperature nonthermal ions affect the basic properties of the dust-acoustic solitary waves. It is also observed that only compressive solitary waves exist in this system.

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

    Science.gov (United States)

    Grosveld, Ferdinand W.

    1996-01-01

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

  9. PVDF-based acoustic sensors prototype for the study of the thermoacoustic model

    Energy Technology Data Exchange (ETDEWEB)

    Drinck, Fabian; Laihem, Karim; Schumann, Manuel; Wiebusch, Christopher [RWTH Aachen University, Physikzentrum, Aachen (Germany)

    2011-07-01

    To measure the ultra-hight energy neutrino flux, studies on a larger IceCube neutrino observatory at the south pole have been intensively investigated in the last years. These studies have introduced a hybrid detection concept including radio and acoustic detection in addition to existing optical detection. The South Pole Acoustic Test Setup (SPATS) was built and deployed to evaluate the acoustic properties of the South Pole ice for the purpose of assessing the feasibility of an acoustic neutrino detection array. The Aachen Acoustic Laboratory (AAL) is supporting these efforts and providing infrastructures for the calibration of PZT-based acoustic sensors used in SPATS, study of a laser-based thermoacoustic model under laboratory conditions and investigating new piezoelectric materials for use in a next generation of acoustic sensors. In this talk we present the R and D status and first results of an acoustic sensor prototype based on PVDF material (Polyvinylidene Fluoride). With a flat frequency response and sensitivity the PVDF response to a thermoacoustic signal has shown the expected bipolar signal free of any superimposed resonances. The analysis of such a clean bipolar signal allow a deeper insight into understanding the thermoacoustic model and leading to a further development of optimized acoustic sensors for deployment at the South Pole.

  10. Solar wind driven dust acoustic instability with Lorentzian kappa distribution

    Energy Technology Data Exchange (ETDEWEB)

    Arshad, Kashif [National Center for Physics (NCP), Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Pakistan Institute of Engineering and Applied Sciences, P.O. Nilore, Islamabad and University of Wah, Wah Cantt 47040 (Pakistan); Ehsan, Zahida, E-mail: Ehsan.zahida@gmail.com [National Center for Physics (NCP), Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Universita degli Studi del Molise, 86090 Pesche - IS (Italy); INFN Sezione di Napoli, 80126 Napoli (Italy); Department of Physics, COMSATS Institute of Information Technology (CIIT), Defence Road, Off Raiwind Road, Lahore 86090 (Pakistan); Khan, S. A. [National Center for Physics (NCP), Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Mahmood, S. [Theoretical Plasma Physics Division, PINSTEC, PO Box Nilore, Islamabad 44000 (Pakistan)

    2014-02-15

    In a three species electron-ion-dust plasma following a generalized non-Maxwellian distribution function (Lorentzian or kappa), it is shown that a kinetic instability of dust-acoustic mode exists. The instability threshold is affected when such (quasineutral) plasma permeates through another static plasma. Such case is of interest when the solar wind is streaming through the cometary plasma in the presence of interstellar dust. In the limits of phase velocity of the waves larger and smaller than the thermal velocity of dust particles, the dispersion properties and growth rate of dust-acoustic mode are investigated analytically with validation via numerical analysis.

  11. Modeling impermeable membranes as acoustic filters for biomedical applications.

    Science.gov (United States)

    Goenaga, Miguel A; Juan, Eduardo J

    2006-01-01

    The main purpose of this research project was to explore a mathematical expression that could be used by medical device designers to appropriately select impermeable membranes to isolate acoustic transducers from water, dust, earwax or other foreign material. The sound transmission properties of various types of impermeable membranes were analytically evaluated and compared to experimental measurements. Computer simulations were also performed to estimate the effects of three key membrane parameters: thickness (h), density (p) and sound speed (c), on the membrane's overall acoustic response. Results indicated that membrane thickness and density affect sound transmission the most. Membrane sound speed had minimal effect on sound transmission.

  12. Seismic wave imaging in visco-acoustic media

    Institute of Scientific and Technical Information of China (English)

    WANG Huazhong; ZHANG Libin; MA Zaitian

    2004-01-01

    Realistic representation of the earth may be achieved by combining the mechanical properties of elastic solids and viscousliquids. That is to say, the amplitude will be attenuated withdifferent frequency and the phase will be changed in the seismicdata acquisition. In the seismic data processing, this effect mustbe compensated. In this paper, we put forward a visco-acoustic wavepropagator which is of better calculating stability and tolerablecalculating cost (little more than an acoustic wave propagator).The quite good compensation effect is demonstrated by thenumerical test results with synthetic seismic data and real data.

  13. Performance of the Aachen Acoustic Laboratory and results from comparative studies in water and ice

    Science.gov (United States)

    Heinen, Dirk; Paul, Larissa; Wiebusch, Christopher

    2013-05-01

    To investigate acoustic ice properties under laboratory conditions and to test the thermoacoustic model, the Aachen Acoustic Laboratory (AAL) was founded as a part of the activities of the acoustic working group (SPATS) within the IceCube collaboration. The goal of SPATS is to evaluate the possibility of acoustic detection of ultra high-energy neutrinos in the Antarctic ice. The AAL provides a test facility setup with a proper infrastructure to study acoustics and thermoacoustics in a large volume of water and ice. The control of the freezing process, the ice quality, the temperature monitoring at different phases of the medium and the laser-based thermoacoustic sound generation are the key features of the setup. The AAL setup provides the possibility for the characterization of a wide range of acoustic transducers, sensor/transmitter calibration, study of the thermoacoustic sound generation, study of the acoustic properties of the ice, water as well as the water/ice interfaces, and research and development of new types of acoustic transducers (PVDF-based) as an alternative to standard PZTs. In this document, the different parts of the AAL setup are described, results on the commissioning from the laser based thermoacoustic sound generation are presented and the performance of an absolute sensor calibration method in water and ice are discussed.

  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. 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.

  18. 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...

  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. Acoustical model of a Shoddy fibre absorber

    Science.gov (United States)

    Manning, John Peter

    Shoddy fibres or "Shoddies" are a mixture of post-consumer and post-industrial fibres diverted from textile waste streams and recycled into their raw fibre form. They have found widespread use as a raw material for manufacturing sound absorbers that include, but are not limited to: automotive, architectural and home appliance applications. The purpose of this project is to develop a simple acoustic model to describe the acoustic behaviour of sound absorbers composed primarily of Shoddy fibres. The model requires knowledge of the material's bulk density only. To date, these materials have not been the focus of much published research and acoustical designers must rely on models that were developed for other materials or are overly complex. For modelling purposes, an equivalent fluid approach is chosen to balance complexity and accuracy. In deriving the proposed model, several popular equivalent fluid models are selected and the required input parameters for each model identified. The models are: the model of Delaney and Bazley, two models by Miki, the model of Johnson in conjunction with the model of Champoux and Allard and the model of Johnson in conjunction with the model of Lafarge. Characterization testing is carried out on sets of Shoddy absorbers produced using three different manufacturing methods. The measured properties are open porosity, tortuosity, airflow resistivity, the viscous and thermal characteristic lengths and the static thermal permeability. Empirical relationships between model parameters and bulk density are then derived and used to populate the selected models. This yields several 'simplified' models with bulk density as the only parameter. The most accurate model is then selected by comparing each model's prediction to the results of normal incidence sound absorption tests. The model of Johnson-Lafarge populated with the empirical relations is the most accurate model over the range of frequencies considered (approx. 300 Hz - 4000 Hz