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Sample records for acoustic microscopy afam

  1. Mapping of elasticity and damping in an α + β titanium alloy through atomic force acoustic microscopy

    PubMed Central

    Phani, M Kalyan; Kumar, Anish; Jayakumar, T; Samwer, Konrad

    2015-01-01

    Summary The distribution of elastic stiffness and damping of individual phases in an α + β titanium alloy (Ti-6Al-4V) measured by using atomic force acoustic microscopy (AFAM) is reported in the present study. The real and imaginary parts of the contact stiffness k * are obtained from the contact-resonance spectra and by using these two quantities, the maps of local elastic stiffness and the damping factor are derived. The evaluation of the data is based on the mass distribution of the cantilever with damped flexural modes. The cantilever dynamics model considering damping, which was proposed recently, has been used for mapping of indentation modulus and damping of different phases in a metallic structural material. The study indicated that in a Ti-6Al-4V alloy the metastable β phase has the minimum modulus and the maximum damping followed by α′- and α-phases. Volume fractions of the individual phases were determined by using a commercial material property evaluation software and were validated by using X-ray diffraction (XRD) and electron back-scatter diffraction (EBSD) studies on one of the heat-treated samples. The volume fractions of the phases and the modulus measured through AFAM are used to derive average modulus of the bulk sample which is correlated with the bulk elastic properties obtained by ultrasonic velocity measurements. The average modulus of the specimens estimated by AFAM technique is found to be within 5% of that obtained by ultrasonic velocity measurements. The effect of heat treatments on the ultrasonic attenuation in the bulk sample could also be understood based on the damping measurements on individual phases using AFAM. PMID:25977847

  2. Local elastic modulus of RF sputtered HfO{sub 2} thin film by atomic force acoustic microscopy

    SciTech Connect

    Jena, S. Tokas, R. B. Sarkar, P. Thakur, S.; Sahoo, N. K.; Misal, J. S.; Rao, K. D.

    2014-04-24

    Atomic force acoustic microscopy (AFAM) is a useful nondestructive technique for measurement of local elastic modulus of materials at nano-scale spatial resolution by measuring the contact resonance spectra for higher order modes of the AFM cantilever. The elastic modulus of RF sputtered HfO{sub 2} thin film has been measured quantitatively, using reference approach in which measurements are performed on the test and reference samples. Using AFAM, the measured elastic modulus of the HfO{sub 2} thin film is 223±27 GPa, which is in agreement with the literature value of 220±40 GPa for atomic layer deposited HfO{sub 2} thin film using nanoindentation technique.

  3. Scanning Tomographic Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Wade, G.; Meyyappan, A.

    1988-07-01

    The technology for "seeing" with sound has an important and interesting history. Some of nature's creatures have been using sound waves for many millenia to image otherwise unobservable objects. The human species, lacking this natural ability, have overcome this deficiency by developing several different ultrasonic imaging techniques. acoustic microscopy is one such technique, which produces high resolution images of detailed structure of small objects in a non-destructive fashion. Two types of acoustic microscopes have evolved for industrial exploitation. They are the scanning laser acoustic microscope (SLAM) and the scanning acoustic microscope (SAM). In this paper, we review the principles of SLAM and describe how we use elements of SLAM to realize the scanning tomographic acoustic microscope (STAM). We describe the data acquisition process and the image reconstruction procedure. We also describe techniques to obtain projection data from different angles of wave incidence enabling us to reconstruct different planes of a complex specimen tomo-graphically. Our experimental results show that STAM is capable of producing high-quality high-resolution subsurface images.

  4. Scanning tomographic acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Hua

    2002-11-01

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

  5. Acoustic transducer for acoustic microscopy

    DOEpatents

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

    1990-01-01

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

  6. Acoustic transducer for acoustic microscopy

    DOEpatents

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

    1990-03-20

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

  7. Elastic Properties of Clay Minerals Determined by Atomic Force Acoustic Microscopy Technique

    NASA Astrophysics Data System (ADS)

    Kopycinska-Müller, M.; Prasad, M.; Rabe, U.; Arnold, W.

    Seismic wave propagation in geological formations is altered by the presence of clay minerals. Knowledge about the elastic properties of clay is therefore essential for the interpretation and modeling of the seismic response of clay-bearing formations. However, due to the layered structure of clay, it is very difficult to investigate its elastic properties. We measured elastic properties of clay using atomic force acoustic microscopy (AFAM). The forces applied during the experiments were not higher than 50 nN. The adhesion forces were measured from the pull-off forces and included into our calculations by means of the Derjaguin-Mueller-Toporov model for contact mechanics. The obtained values of the elastic modulus for clay varied from 10 to 17 GPa depending on various parameters that describe the dynamics of a vibrating beam

  8. Acoustic microscopy of living cells.

    PubMed Central

    Hildebrand, J A; Rugar, D; Johnston, R N; Quate, C F

    1981-01-01

    This paper reports preliminary results of the observation by acoustic microscopy of living cells in vitro. The scanning acoustic microscope uses high-frequency sound waves to produce images with submicrometer resolution. The contrast observed in acoustic micrographs of living cells depends on the acoustic properties (i.e., density, stiffness, and attenuation) and on the topographic contour of the cell. Variation in distance separating the acoustic lens and the viewed cell also has a profound effect on the image. When the substratum is located at the focal plane, thick regions of the cell show a darkening that can be related to cellular acoustic attenuation (a function of cytoplasmic viscosity). When the top of the cell is placed near the focal plane, concentric bright and dark rings appear in the image. The location of the rings can be related to cell topography, and the ring contrast can be correlated to the stiffness and density of the cell. In addition, the character of the images of single cells varies dramatically when the substratum upon which they are grown is changed to a different material. By careful selection of the substratum, the information content of the acoustic images can be increased. Our analysis of acoustic images of actively motile cells indicates that leading lamella are less dense or stiff than the quiescent trailing processes of the cells. Images PMID:6940179

  9. Acoustic impedance microscopy for biological tissue characterization.

    PubMed

    Kobayashi, Kazuto; Yoshida, Sachiko; Saijo, Yoshifumi; Hozumi, Naohiro

    2014-09-01

    A new method for two-dimensional acoustic impedance imaging for biological tissue characterization with micro-scale resolution was proposed. A biological tissue was placed on a plastic substrate with a thickness of 0.5mm. A focused acoustic pulse with a wide frequency band was irradiated from the "rear side" of the substrate. In order to generate the acoustic wave, an electric pulse with two nanoseconds in width was applied to a PVDF-TrFE type transducer. The component of echo intensity at an appropriate frequency was extracted from the signal received at the same transducer, by performing a time-frequency domain analysis. The spectrum intensity was interpreted into local acoustic impedance of the target tissue. The acoustic impedance of the substrate was carefully assessed prior to the measurement, since it strongly affects the echo intensity. In addition, a calibration was performed using a reference material of which acoustic impedance was known. The reference material was attached on the same substrate at different position in the field of view. An acoustic impedance microscopy with 200×200 pixels, its typical field of view being 2×2 mm, was obtained by scanning the transducer. The development of parallel fiber in cerebella cultures was clearly observed as the contrast in acoustic impedance, without staining the specimen. The technique is believed to be a powerful tool for biological tissue characterization, as no staining nor slicing is required. PMID:24852259

  10. Mechanical characterization of porous nano-thin films by use of atomic force acoustic microscopy.

    PubMed

    Kopycinska-Müller, M; Clausner, A; Yeap, K-B; Köhler, B; Kuzeyeva, N; Mahajan, S; Savage, T; Zschech, E; Wolter, K-J

    2016-03-01

    The indentation modulus of thin films of porous organosilicate glass with a nominal porosity content of 30% and thicknesses of 350nm, 200nm, and 46nm is determined with help of atomic force acoustic microscopy (AFAM). This scanning probe microscopy based technique provides the highest possible depth resolution. The values of the indentation modulus obtained for the 350nm and 200nm thin films were respectively 6.3GPa±0.2GPa and 7.2GPa±0.2GPa and free of the substrate influence. The sample with the thickness of 46nm was tested in four independent measurement sets. Cantilevers with two different tip radii of about 150nm and less than 50nm were applied in different force ranges to obtain a result for the indentation modulus that was free of the substrate influence. A detailed data analysis yielded value of 8.3GPa±0.4GPa for the thinnest film. The values of the indentation modulus obtained for the thin films of porous organosilicate glasses increased with the decreasing film thickness. The stiffening observed for the porous films could be explained by evolution of the pore topology as a function of the film thickness. To ensure that our results were free of the substrate influence, we analyzed the ratio of the sample deformation as well as the tip radius to the film thickness. The results obtained for the substrate parameter were compared for all the measurement series and showed, which ones could be declared as free of the substrate influence. PMID:26799327

  11. Acoustic microscopy of silicon carbide materials

    NASA Technical Reports Server (NTRS)

    Khandelwal, P. K.; Heitman, P. W.; Yuhas, D.; Vorres, C. L.

    1982-01-01

    It is shown that scanning laser acoustic microscopy (SLAM) is able to detect such fracture-controlling flaws in dense silicon carbide materials as surface voids, whose diameter-by-depth size is a minimum of 75 by 17 microns in reaction-bonded SiC and 68 by 25 microns in alpha-SiC. Surface conditions such as pitting, which have been found to limit the discernibility of drilled holes, become important when pit and drilled hole sizes become comparable.

  12. What does See the Impulse Acoustic Microscopy inside Nanocomposites?

    NASA Astrophysics Data System (ADS)

    Levin, V. M.; Petronyuk, Y. S.; Morokov, E. S.; Celzard, A.; Bellucci, S.; Kuzhir, P. P.

    The paper presents results of studying bulk microstructure in carbon nanocomposites by impulse acoustic microscopy technique. Nanocomposite materials are in the focus of interest because of their outstanding properties in minimal nanofiller content. Large surface area and high superficial activity cause strong interaction between nanoparticles that can result in formation of fractal conglomerates. This paper involves results of the first direct observation of nanoparticle conglomerates inside the bulk of epoxy-carbon nanocomposites. Diverse types of carbon nanofiller have been under investigation. The impulse acoustic microscope SIAM-1 (Acoustic Microscopy Lab, IBCP RAS) has been employed for 3D imaging bulk microstructure and measuring elastic properties of the nanocomposite specimens. The range of 50-200 MHz allows observing microstructure inside the entire specimen bulk. Acoustic images are obtained in the ultramicroscopic regime; they are formed by the Rayleigh type scattered radiation. It has been found the high-resolution acoustic vision (impulse acoustic microscopy) is an efficient technique to observe mesostructure formed by fractal cluster inside nanocomposites. The clusterization takes its utmost form in nanocomposites with graphite nanoplatelets as nanofiller. The nanoparticles agglomerate into micron-sized conglomerates distributed randomly over the material. Mesostructure in nanocomposites filled with carbon nanotubes is alternation of regions with diverse density of nanotube packing. Regions with alternative density of CNT packing are clearly seen in acoustical images as neighboring pixels of various brightness.

  13. Acoustic microscopy with mixed-mode transducers

    SciTech Connect

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

    1988-12-31

    The new amplitude-phase acoustic microscope is versatile; it operates in a wide frequency range 1--200 MHz, with selection of longitudinal, shear, and mixed modes. This enables it to be used in many NDE applications for different kinds of materials. Besides the application examples presented in this paper (bulk defect imaging of lossy materials or at deep locations; leads of IC chip in epoxy package; amplitude images of surface crack on Si nitride ball bearing; thin Au film on quartz), this system can also be applied for residual stress and anisotropy mapping with high accuracy and good spatial resolution. 7 refs, 6 figs.

  14. Scanning tomographic acoustic microscopy: principles and recent developments (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Wade, G.; Meyyappan, A.

    1987-09-01

    Acoustic Microscopy is an important branch of non-destructive evaluation which provides high resolution for imaging the detailed structure of a small object. When an acoustic microscope operates in the transmission mode, the micrograph is simply a shadowgraph of all the structures encountered by the acoustic wave passing through the object. Because of diffraction and overlapping, the resultant images are difficult to comprehend in the case of specimens of substantial thickness and structural complexity. We used the principles of diffraction tomography and acoustical holography along with digital calcuations of wavefield propagation to overcome this problem. We have described in previously-published work how a scanning laser acoustic microscope (SLAM) can be modified to obtain data for subsurface tomographic imaging. In this paper, we review the principles of scanning tomographic acoustic microscopy (STAM). The required modification of SLAM to obtain STAM and the reconstruction process are described. We show how we are able to accurately acquire the complex-amplitude information necessary for image reconstruction. We demonstrate the power of this technique by comparing digitally-computed images thus obtained with analogue images of a conventional SLAM. The results show that high-quality, high-resolution subsurface images can be obtained from experimentally acquired data. We also describe techniques to obtain projection data from different angles of wave incidence enabling us to tomographically reconstruct different planes of a complex specimen in microscopic detail. With these modifications in place, STAM should shortly become a powerful tool in non-destructive evaluation.

  15. Quantitative flaw characterization with scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Generazio, E. R.; Roth, D. J.

    1986-01-01

    Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. In accuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. The relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness is investigated. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw.

  16. Scanning acoustic microscopy of SCS-6 silicon carbide fiber

    SciTech Connect

    Sathish, S.; Cantrell, J.H.; Yost, W.T.

    1996-01-01

    Scanning acoustic microscopy of SCS-6 silicon carbide fiber reveals large radial variations in acoustic reflectivity associated with the chemical composition and microstructure of a given fiber region. Rayleigh wave fringe patterns observed in each of five subregions are used to calculate the average Young modulus of that subregion. The Young modulus is found to increase monotonically from 40 GPa in the carbon core to a value of 413 GPa in the stoichiometric SiC region. The effective Young modulus of the fiber as a whole is estimated from the moduli of the individual regions and it is compared with mechanical measurements reported in the literature.

  17. Study of cellular adhesion with scanning acoustic microscopy.

    PubMed

    Tittmann, Bernhard R; Miyasaka, Chiaki; Mastro, Andrea M; Mercer, Robyn R

    2007-08-01

    A mechanical scanning acoustic reflection microscope was applied to living cells (e.g., osteoblasts) to observe their undisguised shapes and to evaluate their adhesive conditions at a substrate interface. A conditioned medium was collected from a bone-metastatic breast cancer cell line, MDA-MB-231, and cultured with an immature osteoblast cell line, MC3T3-E1. To characterize the cellular adhesion, MC3T3-E1 osteoblasts were cultured with or without MDA-MB-231 conditioned medium for 2 days, then assayed with the scanning acoustic reflection microscope. At 600 MHz the scanning acoustic reflection microscope clearly indicated that MC3T3-E1 cells cultured with MDA-MB-231 conditioned medium had both an abnormal shape and poor adhesion at the substrate interface. The results are compared with those obtained with laser scanning confocal microscopy and are supported by a simple multilayer model. PMID:17703653

  18. Fundamental Potential for Acoustic Microscopy Evaluation of Dental Tissues

    NASA Astrophysics Data System (ADS)

    Denisova, L. A.; Maev, R. Gr.; Rusanov, F. S.; Maeva, A. R.; Denisov, A. F.; Gavrilov, D. Yu.; Bakulin, E. Yu.; Severin, F. M.

    Comprehensive analysis of the present-day acoustic microscopy experimental approaches from the standpoint of their potential application in dental research and diagnostics has been performed. Whole extracted human teeth and specially prepared dental tissue samples have been investigated. The results of the study demonstrate that there are several experimental techniques that can be used for precise quantitative evaluation of the tissues local mechanical properties in flat-parallel teeth slices, for the pathomorphological investigation of the tissues strength spatial distribution in flat cuts. In the whole tooth, the acoustic microscopy techniques allow us to precisely measure the enamel and dentine layers thickness, the distance between the external surface and pulp, to reveal hidden caries and restoration disbonding. These opportunities form a real ground for the further design of the special acousto-microscopical methods and new equipment for the clinical diagnostics

  19. Osteoblast Adhesion of Breast Cancer Cells with Scanning Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Miyasaka, C.; Mercer, R. R.; Mastro, A. M.

    Conditioned medium was collected from a bone-metastatic breast cancer cell line, MDA-MB-231, and cultured with an immature osteoblast cell line, MC3T3-E1. Under these conditions the osteoblasts acquired a changed morphology and appeared to adhere in a different way to the substrate and to each other. To characterize cellular adhesion, MC3T3-E1 osteoblasts were cultured with or without MDA-MB-231 conditioned medium for two days. With mechanical scanning acoustic reflection microscopy, we were able to detect a change in the adhesive condition of the interface between the cell and the substrate, but not with optical microscopy

  20. Evaluation of the biomechanics of atherosclerosis by acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Saijo, Yoshifumi; Nitta, Shin-ichi; Schiott Jorgensen, Claus; Falk, Erling

    2001-07-01

    Acoustic microscopy provides not only the morphology, but also the biomechanical properties of the biological soft tissues. The biomechanics of atherosclerosis is important because the pathophysiology of atherosclerosis is closely related with mechanical properties and mechanical stress. Rupture of the fibrous cap of atheromatous plaque is the initial event in acute coronary syndrome such as acute myocardial infarction or unstable angina. In addition to extrinsic physical stresses to the plaque, the intrinsic biomechanical property of the plaque is important for assessing the mechanism of the rupture. Two sets of SAMs operating in 100 to 200 MHz and in 800 MHz to 1.3 GHz were equipped to measure the acoustic properties of atherosclerosis of human or mouse arteries. The values of attenuation and sound speed in the tissue components of atherosclerosis were measured by analyzing the frequency dependent characteristics of the amplitude and phase signals. Both values were highest in calcification and lowest in lipid pool. Although attenuation and sound speed were relatively high in intimal fibrosis, the inhomogeneity of acoustic parameters was found within the fibrous cap. Polarized microscopy for the collagen stained with Picrosirius red showed that the attenuation of ultrasound was significantly higher in type I collagen with orange polarized color compared to type III collagen with green color. SAM has shown the possibility to detect the plaque vulnerability and it might improve our understanding of the sudden rupture from micro-mechanical point of view.

  1. Application of acoustic microscopy to assessment of cardiovascular biomechanics

    NASA Astrophysics Data System (ADS)

    Saijo, Yoshifumi; Sasaki, Hidehiko; Nitta, Shin-ichi; Tanaka, Motonao; Joergensen, Claus S.; Falk, Erling

    2002-11-01

    Acoustic microscopy provides information on physical and mechanical properties of biological tissues, while optical microscopy with various staining techniques provides chemical properties. The biomechanics of tissues is especially important in cardiovascular system because its pathophysiology is closely related with mechanical stresses such as blood pressure or blood flow. A scanning acoustic microscope (SAM) system with tone-burst ultrasound in the frequency range of 100-200 MHz has been developed, and attenuation and sound speed of tissues have been measured. In human coronary arteries, attenuation and sound speed were high in calcification and collagen, while both values were low in smooth muscle and lipid. Another SAM system with 800-MHz-1.3-GHz ultrasound was applied for aortas of Apo-E deficient mouse, which is known to develop atherosclerosis. Attenuation of ultrasound was significantly higher in type 1 collagen compared to type 3 collagen. Recently, a new type FFT-SAM using a single-pulse, broadband frequency range ultrasound (20-150 MHz) has been developed. Cardiac allograft was observed by FFT-SAM and the acoustic properties were able to grade allograft rejection. SAM provides very useful information for assessing cardiovascular biomechanics and for understanding normal and abnormal images of clinical ultrasound.

  2. A Modified Algorithm For Scanning Tomographic Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Meyyappan, A.; Wade, G.

    1988-07-01

    Acoustic microscopy is an invaluable tool in non-destructive evaluation because of its ability to provide high-resolution images of microscopic structure in small objects. When such a microscope operates in the transmission mode, the micrograph produced is simply a shadowgraph of all the struc-tures encountered by the acoustic wave passing through the object. Because of diffraction and over-lapping, the resultant images are difficult to comprehend, especially in the case of objects of sub-stantial thickness with complex structures. To over-come these problems, we have developed a scanning tomographic acoustic microscope (STAM) which is capable of producing unambiguous high-resolution tomograms. We have described in previously-published work how a scanning laser acoustic micro-scope can be employed to realize STAM. We use an algorithm based on "back-and-forth propagation" to reconstruct tomograms of the various layers to be imaged. When these layers are physically close to one another, we see ambiguities in the reconstructions. In this paper we describe a modified algorithm which removes these ambiguities. With the new algorithm, we can resolve layers that are only two wavelengths apart.

  3. Multispectral photoacoustic microscopy based on an optical–acoustic objective

    PubMed Central

    Cao, Rui; Kilroy, Joseph P.; Ning, Bo; Wang, Tianxiong; Hossack, John A.; Hu, Song

    2015-01-01

    We have developed reflection-mode multispectral photoacoustic microscopy (PAM) based on a novel optical–acoustic objective that integrates a customized ultrasonic transducer and a commercial reflective microscope objective into one solid piece. This technical innovation provides zero chromatic aberration and convenient confocal alignment of the optical excitation and acoustic detection. With a wavelength-tunable optical-parametric-oscillator laser, we have demonstrated multispectral PAM over an ultrabroad spectral range of 270–1300 nm. A near-constant lateral resolution of ∼2.8 μm is achieved experimentally. Capitalizing on the consistent performance over the ultraviolet, visible, and near-infrared range, multispectral PAM enables label-free concurrent imaging of cell nucleus (DNA/RNA contrast at 270 nm), blood vessel (hemoglobin contrast at 532 nm), and sebaceous gland (lipid contrast at 1260 nm) at the same spatial scale in a living mouse ear. PMID:26236641

  4. Mechanisms of CFR composites destruction studying with pulse acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Petronyuk, Y. S.; Morokov, E. S.; Levin, V. M.; Ryzhova, T. B.; Chernov, A. V.

    2016-05-01

    Non-destructive inspection of carbon-fiber-reinforced (CFR) composites applied in aerospace industry attracts a wide attention. In the paper, high frequency focused ultrasound (50-100 MHz) has been applied to study the bulk microstructure of the CFR material and mechanisms of its destruction under the mechanical loading. It has been shown impulse acoustic microscopy provides detecting the areas of adhesion loss at millimeter and micron level. Behavior of the CFR laminate structure fabricated by prepreg or infusion technology has been investigated under the tensile and impact loading.

  5. Testing of metal-ceramic joint using scanning acoustic microscopy.

    PubMed

    Könönen, M; Kivilahti, J

    1991-07-01

    The objective of the investigation was to compare the results obtained from examination of titanium-porcelain joints by means of both scanning acoustic microscopy (C-SAM) and scanning electron microscopy (SEM). A dental porcelain (Ducera, Dental GmbH) mechanically compatible with titanium was fired to sand-blasted or electrolytically polished commercially pure titanium (grade 1) specimens. The firing was carried out in an ordinary dental furnace according to manufacturer's instructions. There was a good correlation between the C-SAM and SEM methods regarding the ability to detect air-filled defects in the porcelain/titanium interface. The results show that the C-SAM method, being non-destructive as well as time-and-money-saving, can be useful in the testing of metal-ceramic joints. PMID:1813346

  6. In vivo switchable optical- and acoustic-resolution photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Jeon, Seungwan; Kim, Jaewoo; Kim, Chulhong

    2016-03-01

    Photoacoustic microscopy (PAM) provides high resolution and large penetration depth by utilizing the high optical sensitivity and low scattering of ultrasound. Hybrid PAM systems can be classified into two categories: opticalresolution photoacoustic microscopy (OR-PAM) and acoustic-resolution photoacoustic microscopy (AR-PAM). ORPAM provides a very high lateral resolution with a strong optical focus, but the penetration depth is limited to one optical transport mean free path. AR-PAM provides a relatively greater penetration depth using diffused light in biological tissues. The resolution of AR-PAM is determined by its ultrasonic parameters. In this study, we performed an in vivo testing of a switchable OR-/AR-PAM system. In this system, two modes can be switched by changing its collimator lens and optical fiber. The lateral resolution of OR-PAM was measured using a resolution test target, and the full width at half maximum (FWHM) of the edge spread function was 2.5 μm. To calculate the lateral resolution of ARPAM, a 6-μm-diameter carbon fiber was used, and the FWHM of the line spread function was 80.2 μm. We successfully demonstrated the multiscale imaging capability of the switchable OR-/AR-PAM system by visualizing microvascular networks in mouse ears, brain, legs, skin, and eyes.

  7. Scanning acoustic microscopy study of human cortical and trabecular bone.

    PubMed

    Bumrerraj, S; Katz, J L

    2001-12-01

    Scanning acoustic microscopy (SAM) has been used in the burst mode to study the properties of human cortical and trabecular bone. An Olympus UH3 SAM (Olympus Co., Tokyo, Japan) was used with a 400 MHz burst mode lens (120 degrees aperture, nominal lateral resolution 2.5 microm). The human cortical bone was from the midshaft of a femur from a 60+ male cadaver; the trabecular bone specimens were obtained from the distal femoral condyles of another 60+ human male cadaver. Elastic moduli for both trabecular and cortical bone were obtained by means of a series of calibration curves correlating SAM gray levels of known materials with their elastic moduli; specimens included: polypropylene, PMMA, Teflon, aluminum, Pyrex glass, titanium, and stainless steel. Values obtained by this method are in good agreement with those obtained by nanoindentation techniques. The three critical findings earlier by Katz and Meunier were observed here as well in both the cortical and trabecular bone samples. PMID:11853252

  8. Mechanical property quantification of endothelial cells using scanning acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Shelke, A.; Brand, S.; Kundu, T.; Bereiter-Hahn, J.; Blase, C.

    2012-04-01

    The mechanical properties of cells reflect dynamic changes of cellular organization which occur during physiologic activities like cell movement, cell volume regulation or cell division. Thus the study of cell mechanical properties can yield important information for understanding these physiologic activities. Endothelial cells form the thin inner lining of blood vessels in the cardiovascular system and are thus exposed to shear stress as well as tensile stress caused by the pulsatile blood flow. Endothelial dysfunction might occur due to reduced resistance to mechanical stress and is an initial step in the development of cardiovascular disease like, e.g., atherosclerosis. Therefore we investigated the mechanical properties of primary human endothelial cells (HUVEC) of different age using scanning acoustic microscopy at 1.2 GHz. The HUVECs are classified as young (tD < 90 h) and old (tD > 90 h) cells depending upon the generation time for the population doubling of the culture (tD). Longitudinal sound velocity and geometrical properties of cells (thickness) were determined using the material signature curve V(z) method for variable culture condition along spatial coordinates. The plane wave technique with normal incidence is assumed to solve two-dimensional wave equation. The size of the cells is modeled using multilayered (solid-fluid) system. The propagation of transversal wave and surface acoustic wave are neglected in soft matter analysis. The biomechanical properties of HUVEC cells are quantified in an age dependent manner.

  9. Acoustic and photoacoustic microscopy imaging of single leukocytes

    NASA Astrophysics Data System (ADS)

    Strohm, Eric M.; Moore, Michael J.; Kolios, Michael C.

    2016-03-01

    An acoustic/photoacoustic microscope was used to create micrometer resolution images of stained cells from a blood smear. Pulse echo ultrasound images were made using a 1000 MHz transducer with 1 μm resolution. Photoacoustic images were made using a fiber coupled 532 nm laser, where energy losses through stimulated Raman scattering enabled output wavelengths from 532 nm to 620 nm. The laser was focused onto the sample using a 20x objective, and the laser spot co-aligned with the 1000 MHz transducer opposite the laser. The blood smear was stained with Wright-Giemsa, a common metachromatic dye that differentially stains the cellular components for visual identification. A neutrophil, lymphocyte and a monocyte were imaged using acoustic and photoacoustic microscopy at two different wavelengths, 532 nm and 600 nm. Unique features in each imaging modality enabled identification of the different cell types. This imaging method provides a new way of imaging stained leukocytes, with applications towards identifying and differentiating cell types, and detecting disease at the single cell level.

  10. Actuation of atomic force microscopy microcantilevers using contact acoustic nonlinearities

    SciTech Connect

    Torello, D.; Degertekin, F. Levent

    2013-11-15

    A new method of actuating atomic force microscopy (AFM) cantilevers is proposed in which a high frequency (>5 MHz) wave modulated by a lower frequency (∼300 kHz) wave passes through a contact acoustic nonlinearity at the contact interface between the actuator and the cantilever chip. The nonlinearity converts the high frequency, modulated signal to a low frequency drive signal suitable for actuation of tapping-mode AFM probes. The higher harmonic content of this signal is filtered out mechanically by the cantilever transfer function, providing for clean output. A custom probe holder was designed and constructed using rapid prototyping technologies and off-the-shelf components and was interfaced with an Asylum Research MFP-3D AFM, which was then used to evaluate the performance characteristics with respect to standard hardware and linear actuation techniques. Using a carrier frequency of 14.19 MHz, it was observed that the cantilever output was cleaner with this actuation technique and added no significant noise to the system. This setup, without any optimization, was determined to have an actuation bandwidth on the order of 10 MHz, suitable for high speed imaging applications. Using this method, an image was taken that demonstrates the viability of the technique and is compared favorably to images taken with a standard AFM setup.

  11. Actuation of atomic force microscopy microcantilevers using contact acoustic nonlinearities.

    PubMed

    Torello, D; Degertekin, F Levent

    2013-11-01

    A new method of actuating atomic force microscopy (AFM) cantilevers is proposed in which a high frequency (>5 MHz) wave modulated by a lower frequency (~300 kHz) wave passes through a contact acoustic nonlinearity at the contact interface between the actuator and the cantilever chip. The nonlinearity converts the high frequency, modulated signal to a low frequency drive signal suitable for actuation of tapping-mode AFM probes. The higher harmonic content of this signal is filtered out mechanically by the cantilever transfer function, providing for clean output. A custom probe holder was designed and constructed using rapid prototyping technologies and off-the-shelf components and was interfaced with an Asylum Research MFP-3D AFM, which was then used to evaluate the performance characteristics with respect to standard hardware and linear actuation techniques. Using a carrier frequency of 14.19 MHz, it was observed that the cantilever output was cleaner with this actuation technique and added no significant noise to the system. This setup, without any optimization, was determined to have an actuation bandwidth on the order of 10 MHz, suitable for high speed imaging applications. Using this method, an image was taken that demonstrates the viability of the technique and is compared favorably to images taken with a standard AFM setup. PMID:24289402

  12. Characterization of the geometry of microscale periodic structures using acoustic microscopy.

    PubMed

    Shaw, Anurupa; Liu, Jingfei; Yoon, Suk Wang; Declercq, Nico F

    2016-08-01

    Periodic structures are very common in both scientific investigations and engineering applications. The geometry of the periodic structure is important for its designed functionality. Although the techniques such as optical and electron microscopy are capable of measuring the periodicity of microscale periodically-corrugated structures, they cannot be used to measure the height or depth of the corrugation. The technique of acoustic microscopy has been developed rapidly and it has been applied in the studies of steel integrated structures, ferro-elastic ceramics, human retina, semiconductors, composites, etc. In acoustic microscopy, V(z) curves have been used to investigate the visco-elastic parameters of thin sliced samples of composites, animal tissue, etc., while in this work it is applied in characterizing the geometry of periodically corrugated structures. The measurements of the geometry of periodic structures obtained using acoustic microscopy are compared with those obtained using optical microscopy, and the reliability of this acoustic technique is also examined. PMID:27259118

  13. Characterization of renal angiomyolipoma by scanning acoustic microscopy.

    PubMed

    Sasaki, H; Saijo, Y; Tanaka, M; Nitta, S; Yambe, T; Terasawa, Y

    1997-04-01

    A scanning acoustic microscope system was used to differentiate renal angiomyolipoma from renal cell carcinoma. The ultrasonic frequency used ranged from 100 to 200 MHz, and the attenuation constant and sound speed were measured on a two-dimensional distribution. The sound speed was significantly lower for lipoma cells than for vessels, smooth muscle fibres, clear cell renal cancer or granular cell renal cancer. The attenuation constant was significantly lower for lipoma cells than for vessels or clear cells. Both acoustic parameters for smooth muscle fibres were significantly lower than for vessels. The heterogeneity of the microacoustic field in renal angiomyolipoma is closely related to the high intensity echo observed on clinical echography. Renal angiomyolipoma and renal cell carcinoma can thus be distinguished by acoustic examination. PMID:9196446

  14. Scanning probe acoustic microscopy of extruded starch materials: direct visual evidence of starch crystal.

    PubMed

    Liu, Zhongdong; Liu, Boxiang; Li, Mengxing; Wei, Min; Li, Hua; Liu, Peng; Wan, Tuo

    2013-10-15

    Scanning probe acoustic microscopy (SPAM) has been successfully used to study inorganic and keratin biomaterials. However, few studies have attempted to apply SPAM to structural study of non-keratin organic materials such as starch based materials. This study investigated hardness and surface finish to establish sample preparation method suitable for SPAM imaging and acquired clear acoustic images of extruded starch materials. Acquired acoustic images directly exhibited certain structure of starch materials and provided visual evidence of starch material components and aggregates. In addition, through correlating acoustic images with X-ray diffraction data, crystal-structural information in nano-scale was obtained and acoustic image contrast showed a linear relationship with starch amylose content in extruded starch materials. PMID:23987357

  15. Characterizing intestinal strictures with acoustic resolution photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Lei, Hao; Xu, Guan; Liu, Shengchun; Johnson, Laura A.; Moons, David S.; Higgins, Peter D. R.; Rice, Michael D.; Ni, Jun; Wang, Xueding

    2016-03-01

    Crohn's disease (CD) is an autoimmune disease, which may cause obstructing intestinal strictures due to inflammation, fibrosis (deposition of collagen), or a combination of both. Identifying the different stages of the disease progression is still challenging. In this work, we indicated the feasibility of non-invasively characterizing intestinal strictures using photoacoustic imaging (PAI), utilizing the uniquely optical absorption of hemoglobin and collagen. Surgically removed human intestinal stricture specimens were investigated with a prototype PAI system. 2D PA images with acoustic resolution at wavelength 532, 1210 and 1310 nm were formulated, and furthermore, the PA histochemical components images which show the microscopic distributions of histochemical components were solved. Imaging experiments on surgically removed human intestinal specimens has demonstrated the solved PA images were significantly different associated with the presence of fibrosis, which could be applied to characterize the intestinal strictures for given specimens.

  16. Elastic characterization of swine aorta by scanning acoustic microscopy at 30 MHz

    NASA Astrophysics Data System (ADS)

    Blase, Christopher; Shelke, Amit; Kundu, Tribikram; Bereiter-Hahn, Jürgen

    2011-04-01

    The mechanical properties of blood vessel walls are important determinants of physiology and pathology of the cardiovascular system. Acoustic imaging (B mode) is routinely used in a clinical setting to determine blood flow and wall distensibility. In this study scanning acoustic microscopy in vitro is used to determine spatially resolved tissue elastic properties. Broadband excitation of 30 MHz has been applied through scanning acoustic microscopy (SAM) for topographical imaging of swine thoracic aorta in reflection mode. Three differently treated tissue samples were investigated with SAM: a) treated with elastase to remove elastin, b) autoclaving for 5 hours to remove collagen and c) fresh controlled untreated sample as control. Experimental investigations are conducted for studying the contribution of individual protein components (elastin and collagen) to the material characteristics of the aortic wall. Conventional tensile testing has been conducted on the tissue samples to study the mechanical behavior. The mechanical properties measured by SAM and tensile testing show qualitative agreement.

  17. Acoustic Microscopy for Visualization and Evaluation of Ceramic-ceramic Contact Zone

    NASA Astrophysics Data System (ADS)

    Morokov, E. S.; Levin, V. M.; Petronyuk, Yu. S.; Podzorova, L. I.; Il'Icheva, A. A.; Lebedenko, I. Yu.; Anisimova, S. V.

    Impulse acoustic microscopy technique has been applied for investigation of features of ceramic-ceramic contact zone. At the interface the method allows to identified and localized detachment and extended partial contact area (kissing contact), shown distribution of the thickness of the interlayer and its homogeneity.

  18. Early detection of melanoma with the combined use of acoustic microscopy, infrared reflectance and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Karagiannis, Georgios T.; Grivas, Ioannis; Tsingotjidou, Anastasia; Apostolidis, Georgios K.; Grigoriadou, Ifigeneia; Dori, I.; Poulatsidou, Kyriaki-Nefeli; Doumas, Argyrios; Wesarg, Stefan; Georgoulias, Panagiotis

    2015-03-01

    Malignant melanoma is a form of skin cancer, with increasing incidence worldwide. Early diagnosis is crucial for the prognosis and treatment of the disease. The objective of this study is to develop a novel animal model of melanoma and apply a combination of the non-invasive imaging techniques acoustic microscopy, infrared (IR) and Raman spectroscopies, for the detection of developing tumors. Acoustic microscopy provides information about the 3D structure of the tumor, whereas, both spectroscopic modalities give qualitative insight of biochemical changes during melanoma development. In order to efficiently set up the final devices, propagation of ultrasonic and electromagnetic waves in normal skin and melanoma simulated structures was performed. Synthetic and grape-extracted melanin (simulated tumors), endermally injected, were scanned and compared to normal skin. For both cases acoustic microscopy with central operating frequencies of 110MHz and 175MHz were used, resulting to the tomographic imaging of the simulated tumor, while with the spectroscopic modalities IR and Raman differences among spectra of normal and melanin- injected sites were identified in skin depth. Subsequently, growth of actual tumors in an animal melanoma model, with the use of human malignant melanoma cells was achieved. Acoustic microscopy and IR and Raman spectroscopies were also applied. The development of tumors at different time points was displayed using acoustic microscopy. Moreover, the changes of the IR and Raman spectra were studied between the melanoma tumors and adjacent healthy skin. The most significant changes between healthy skin and the melanoma area were observed in the range of 900-1800cm-1 and 350-2000cm-1, respectively.

  19. OSTEOBLAST ADHESION OF BREAST CANCER CELLS WITH SCANNING ACOUSTIC MICROSCOPY

    SciTech Connect

    Chiaki Miyasaka; Robyn R. Mercer; Andrea M. Mastro; Ken L. Telschow

    2005-03-01

    Breast cancer frequently metastasizes to the bone. Upon colonizing bone tissue, the cancer cells stimulate osteoclasts (cells that break bone down), resulting in large lesions in the bone. The breast cancer cells also affect osteoblasts (cells that build new bone). Conditioned medium was collected from a bone-metastatic breast cancer cell line, MDA-MB-231, and cultured with an immature osteoblast cell line, MC3T3-E1. Under these conditions the osteoblasts acquired a changed morphology and appeared to adherer in a different way to the substrate and to each other. To characterize cell adhesion, MC3T3-E1 osteoblasts were cultured with or without MDA-MB-231 conditioned medium for two days, and then assayed with a mechanical scanning acoustic reflection microscope (SAM). The SAM indicated that in normal medium the MC3T3-E1 osteoblasts were firmly attached to their plastic substrate. However, MC3T3-E1 cells cultured with MDA-MB-231 conditioned medium displayed both an abnormal shape and poor adhesion at the substrate interface. The cells were fixed and stained to visualize cytoskeletal components using optical microscopic techniques. We were not able to observe these differences until the cells were quite confluent after 7 days of culture. However, using the SAM, we were able to detect these changes within 2 days of culture with MDA-MB-231 conditioned medium

  20. Quantitative void characterization in structural ceramics using scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Generazio, E. R.; Baaklini, G. Y.

    1986-01-01

    The ability of scanning laser acoustic microscopy (SLAM) to characterize artificially seeded voids in sintered silicon nitride structural ceramic specimens was investigated. Using trigonometric relationships and Airy's diffraction theory, predictions of internal void depth and size were obtained from acoustic diffraction patterns produced by the voids. Agreement was observed between actual and predicted void depths. However, predicted void diameters were generally much greater than actual diameters. Precise diameter predictions are difficult to obtain due to measurement uncertainty and the limitations of 100 MHz SLAM applied to typical ceramic specimens.

  1. An acoustic microscopy technique reveals hidden morphological defenses in Daphnia.

    PubMed

    Laforsch, Christian; Ngwa, Wilfred; Grill, Wolfgang; Tollrian, Ralph

    2004-11-01

    Inducible defenses are common strategies for coping with the selective force of predation in heterogeneous environments. In recent years the conspicuous and often dramatic morphological plasticity of several waterflea species of the genus Daphnia have been found to be inducible defenses activated by chemical cues released by predators. However, the exact defensive mechanisms remained mysterious. Because even some minute morphological alterations proved to be protective against predatory invertebrates, it has been suggested that the visible morphological changes are only the tip of the iceberg of the entire protective mechanisms. Here we applied a method of ultrasonic microscopy with vector contrast at 1.2 GHz to probe hidden morphological defenses. We found that induction with predator kairomones increases the stability of the carapace in two Daphnia species up to 350%. This morphological plasticity provides a major advantage for the induced morphs during predation because predatory invertebrates need to crush or puncture the carapace of their prey to consume them. Our ultrastructural analyses revealed that the internal architecture of the carapace ensures maximal rigidity with minimal material investment. Our results uncover hidden morphological plasticity and suggest a reconsideration of former classification systems in defended and undefended genotypes in Daphnia and possibly in other prey organisms as well. PMID:15520396

  2. Ultrasonic Quantification of Tumor Interstitial Fluid Pressure Through Scanning Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Pflanzer, Ralph; Shelke, Amit; Bereiter-Hahn, Jürgen; Hofmann, Matthias

    High tumor interstitial fluid pressure (TIFP) is characteristic of solid tumors. Elevated TIFP inhibits the assimilation of macromolecular therapeutics in tumor tissue as well as it induces mechanical strain triggering cell proliferation in solid tumors. Common solid epithelial tumors of A431 carcinoma cells exhibit a TIFP of about 10-15 mmHg measured conventionally through wick-in-needle technique. A new scheme to determine topography and acoustic impedance in solid tumor is proposed through scanning acoustic microscopy. The change in amplitude and time of flight at 30 MHz acoustic signal is used to quantify the growth pattern and to calibrate elevation of TIFP. The wide variability of amplitude and frequency in topographic sections indicate discrete envelopes of individual tumors with localized TIFP. Further investigations in applying this non-invasive method as a means of measuring TIFP in subcutaneous mice xenograft tumors in situ could also enhance understanding of tumor microenvironment and vessel architecture in living tissue.

  3. Bulk microstructure and local elastic properties of carbon nanocomposites studied by impulse acoustic microscopy technique

    NASA Astrophysics Data System (ADS)

    Levin, V.; Petronyuk, Yu.; Morokov, E.; Chernozatonskii, L.; Kuzhir, P.; Fierro, V.; Celzard, A.; Bellucci, S.; Bistarelli, S.; Mastrucci, M.; Tabacchioni, I.

    2016-05-01

    Bulk microstructure and elastic properties of epoxy-nanocarbon nanocomposites for diverse types and different content of carbon nanofiller has been studied by using impulse acoustic microscopy technique. It has been shown occurrence of various types of mesoscopic structure formed by nanoparticles inside the bulk of nanocomposite materials, including nanoparticle conglomerates and nanoparticle aerogel systems. In spite of the bulk microstructure, nanocarbon composites demonstrate elastic uniformity and negligible influence of nanofiller on elastic properties of carbon nanocomposite materials.

  4. Detection and quantification of bacterial biofilms combining high-frequency acoustic microscopy and targeted lipid microparticles

    PubMed Central

    2014-01-01

    Background Immuno-compromised patients such as those undergoing cancer chemotherapy are susceptible to bacterial infections leading to biofilm matrix formation. This surrounding biofilm matrix acts as a diffusion barrier that binds up antibiotics and antibodies, promoting resistance to treatment. Developing non-invasive imaging methods that detect biofilm matrix in the clinic are needed. The use of ultrasound in conjunction with targeted ultrasound contrast agents (UCAs) may provide detection of early stage biofilm matrix formation and facilitate optimal treatment. Results Ligand-targeted UCAs were investigated as a novel method for pre-clinical non-invasive molecular imaging of early and late stage biofilms. These agents were used to target, image and detect Staphylococcus aureus biofilm matrix in vitro. Binding efficacy was assessed on biofilm matrices with respect to their increasing biomass ranging from 3.126 × 103 ± 427 UCAs per mm2 of biofilm surface area within 12 h to 21.985 × 103 ± 855 per mm2 of biofilm matrix surface area at 96 h. High-frequency acoustic microscopy was used to ultrasonically detect targeted UCAs bound to a biofilm matrix and to assess biofilm matrix mechanoelastic physical properties. Acoustic impedance data demonstrated that biofilm matrices exhibit impedance values (1.9 MRayl) close to human tissue (1.35 - 1.85 MRayl for soft tissues). Moreover, the acoustic signature of mature biofilm matrices were evaluated in terms of integrated backscatter (0.0278 - 0.0848 mm-1 × sr-1) and acoustic attenuation (3.9 Np/mm for bound UCAs; 6.58 Np/mm for biofilm alone). Conclusions Early diagnosis of biofilm matrix formation is a challenge in treating cancer patients with infection-associated biofilms. We report for the first time a combined optical and acoustic evaluation of infectious biofilm matrices. We demonstrate that acoustic impedance of biofilms is similar to the impedance of human tissues, making in vivo imaging and detection of biofilm

  5. Evaluation of the implant type tissue-engineered cartilage by scanning acoustic microscopy.

    PubMed

    Tanaka, Yoko; Saijo, Yoshifumi; Fujihara, Yuko; Yamaoka, Hisayo; Nishizawa, Satoru; Nagata, Satoru; Ogasawara, Toru; Asawa, Yukiyo; Takato, Tsuyoshi; Hoshi, Kazuto

    2012-02-01

    The tissue-engineered cartilages after implantation were nonuniform tissues which were mingling with biodegradable polymers, regeneration cartilage and others. It is a hard task to evaluate the biodegradation of polymers or the maturation of regenerated tissues in the transplants by the conventional examination. Otherwise, scanning acoustic microscopy (SAM) system specially developed to measure the tissue acoustic properties at a microscopic level. In this study, we examined acoustic properties of the tissue-engineered cartilage using SAM, and discuss the usefulness of this devise in the field of tissue engineering. We administered chondrocytes/atelocollagen mixture into the scaffolds of various polymers, and transplanted the constructs in the subcutaneous areas of nude mice for 2 months. We harvested them and examined the sound speed and the attenuation in the section of each construct by the SAM. As the results, images mapping the sound speed exhibited homogenous patterns mainly colored in blue, in all the tissue-engineered cartilage constructs. Contrarily, the images of the attenuation by SAM showed the variation of color ranged between blue and red. The low attenuation area colored in red, which meant hard materials, were corresponding to the polymer remnant in the toluidine blue images. The localizations of blue were almost similar with the metachromatic areas in the histology. In conclusion, the SAM is regarded as a useful tool to provide the information on acoustic properties and their localizations in the transplants that consist of heterogeneous tissues with various components. PMID:22138383

  6. Investigation of Local Elastic Properties in Friction Stir Welded TI-6AL-4V Using Scanning Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Martin, Richard W.; Sathish, Shamachary; Jata, Kumar V.

    2008-02-01

    Local changes in the microstructure and ultrasonic wave velocity variation across a friction weld in Ti-6A1-4V are investigated using scanning acoustic microscopy. Surface and bulk acoustic wave velocity and amplitude measurements performed across the weld are presented. The changes in the characteristics of the surface waves are related to the near surface microstructure in different parts of the weld. The bulk velocity and amplitude changes thru the thickness show bright and dark bands particularly in the nugget region. Possible reasons for formation of such bands are discussed. Application of acoustic microscopy to detect localized process induced defects in friction stir welds is discussed.

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

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Qian, Menglu

    1992-01-01

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

  8. Scanning Acoustic Microscopy for Characterization of Coatings and Near-Surface Features of Ceramics

    SciTech Connect

    Qu, Jun; Blau, Peter Julian

    2006-01-01

    Scanning Acoustic Microscopy (SAcM) has been widely used for non-destructive evaluation (NDE) in various fields such as material characterization, electronics, and biomedicine. SAcM uses high-frequency acoustic waves (60 MHz to 2.0 GHz) providing much higher resolution (up to 0.5 {micro}m) compared to conventional ultrasonic NDE, which is typically about 500 {micro}m. SAcM offers the ability to non-destructively image subsurface features and visualize the variations in elastic properties. These attributes make SAcM a valuable tool for characterizing near-surface material properties and detecting fine-scale flaws. This paper presents some recent applications of SAcM in detecting subsurface damage, assessing coatings, and visualizing residual stress for ceramic and semiconductor materials.

  9. Properties of cells through life and death – an acoustic microscopy investigation

    PubMed Central

    Pasternak, Maurice M; Strohm, Eric M; Berndl, Elizabeth SL; Kolios, Michael C

    2015-01-01

    Current methods to evaluate the status of a cell are largely focused on fluorescent identification of molecular biomarkers. The invasive nature of these methods – requiring either fixation, chemical dyes, genetic alteration, or a combination of these – prevents subsequent analysis of samples. In light of this limitation, studies have considered the use of physical markers to differentiate cell stages. Acoustic microscopy is an ultrahigh frequency (>100 MHz) ultrasound technology that can be used to calculate the mechanical and physical properties of biological cells in real-time, thereby evaluating cell stage in live cells without invasive biomarker evaluation. Using acoustic microscopy, MCF-7 human breast adenocarcinoma cells within the G1, G2, and metaphase phases of the proliferative cell cycle, in addition to early and late programmed cell death, were examined. Physical properties calculated include the cell height, sound speed, acoustic impedance, cell density, adiabatic bulk modulus, and the ultrasonic attenuation. A total of 290 cells were measured, 58 from each cell phase, assessed using fluorescent and phase contrast microscopy. Cells actively progressing from G1 to metaphase were marked by a 28% decrease in attenuation, in contrast to the induction of apoptosis from G1, which was marked by a significant 81% increase in attenuation. Furthermore late apoptotic cells separated into 2 distinct groups based on ultrasound attenuation, suggesting that presently-unidentified sub-stages may exist within late apoptosis. A methodology has been implemented for the identification of cell stages without the use of chemical dyes, fixation, or genetic manipulation. PMID:26178635

  10. Reliability of scanning laser acoustic microscopy for detecting internal voids in structural ceramics

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Baaklini, G. Y.

    1986-01-01

    The reliability of 100 MHz scanning laser acoustic microscopy (SLAM) for detecting internal voids in sintered specimens of silicon nitride and silicon carbide was evaluated. The specimens contained artificially implanted voids and were positioned at depths ranging up to 2 mm below the specimen surface. Detection probability of 0.90 at a 0.95 confidence level was determined as a function of material, void diameter, and void depth. The statistical results presented for void detectability indicate some of the strengths and limitations of SLAM as a nondestructive evaluation technique for structural ceramics.

  11. Cutting down the forest of peaks in acoustic dynamic atomic force microscopy in liquid.

    PubMed

    Carrasco, C; Ares, P; de Pablo, P J; Gómez-Herrero, J

    2008-12-01

    Acoustic dynamic force microscopy in liquids is a fundamental technique for the investigation of biological samples under physiological conditions. However, it shows an important drawback that consists of producing a myriad of resonance peaks, known as the forest of peaks, which hides the natural resonance frequency of the cantilever and prevents an optimum operation of the microscope. In this work, we propose a simple remedy for this problem, which consists on adding a small clay damper to the dither piezoelectric. The resulting frequency spectrum exhibits a single resonance peak that is comparable with the one obtained using magnetic excitation. PMID:19123597

  12. Microstructure-Sensitive Investigation of Fracture Using Acoustic Emission Coupled With Electron Microscopy

    NASA Technical Reports Server (NTRS)

    Wisner, Brian; Cabal, Mike; Vanniamparambiland, Prashanth A.; Leser, William; Hochhalter, Jacob; Kontsos, Antonios

    2015-01-01

    A novel technique using Scanning Electron Microscopy (SEM) in conjunction with Acoustic Emission (AE) monitoring is proposed to investigate microstructure-sensitive fatigue and fracture of metals. The coupling between quasi in situ microscopy with actual in situ nondestructive evaluation falls into the ICME framework and the idea of quantitative data-driven characterization of material behavior. To validate the use of AE monitoring inside the SEM chamber, Aluminum 2024-B sharp notch specimen were tested both inside and outside the microscope using a small scale mechanical testing device. Subsequently, the same type of specimen was tested inside the SEM chamber. Load data were correlated with both AE information and observations of microcracks around grain boundaries as well as secondary cracks, voids, and slip bands. The preliminary results are in excellent agreement with similar findings at the mesoscale. Extensions of the application of this novel technique are discussed.

  13. Whispering-gallery acoustic sensing: characterization of mesoscopic films and scanning probe microscopy applications.

    PubMed

    La Rosa, Andres H; Li, Nan; Fernandez, Rodolfo; Wang, Xiaohua; Nordstrom, Richard; Padigi, S K

    2011-09-01

    Full understanding of the physics underlying the striking changes in viscoelasticity, relaxation time, and phase transitions that mesoscopic fluid-like films undergo at solid-liquid interfaces, or under confinement between two sliding solid boundaries, constitutes one of the major challenges in condensed matter physics. Their role in the imaging process of solid substrates by scanning probe microscopy (SPM) is also currently controversial. Aiming at improving the reliability and versatility of instrumentation dedicated to characterize mesoscopic films, a noninvasive whispering-gallery acoustic sensing (WGAS) technique is introduced; its application as feedback control in SPM is also demonstrated. To illustrate its working principle and potential merits, WGAS has been integrated into a SPM that uses a sharp tip attached to an electrically driven 32-kHz piezoelectric tuning fork (TF), the latter also tighten to the operating microscope's frame. Such TF-based SPMs typically monitor the TF's state of motion by electrical means, hence subjected to the effects caused by the inherent capacitance of the device (i.e., electrical resonance differing from the probe's mechanical resonance). Instead, the novelty of WGAS resides in exploiting the already existent microscope's frame as an acoustic cavity (its few centimeter-sized perimeter closely matching the operating acoustic wavelength) where standing-waves (generated by the nanometer-sized oscillations of the TF's tines) are sensitively detected by an acoustic transducer (the latter judiciously placed around the microscope's frame perimeter for attaining maximum detection). This way, WGAS is able to remote monitoring, via acoustic means, the nanometer-sized amplitude motion of the TF's tines. (This remote-detection method resembles the ability to hear faint, but still clear, levels of sound at the galleries of a cathedral, despite the extraordinary distance location of the sound source.) In applications aiming at

  14. Whispering-gallery acoustic sensing: Characterization of mesoscopic films and scanning probe microscopy applications

    NASA Astrophysics Data System (ADS)

    La Rosa, Andres H.; Li, Nan; Fernandez, Rodolfo; Wang, Xiaohua; Nordstrom, Richard; Padigi, S. K.

    2011-09-01

    Full understanding of the physics underlying the striking changes in viscoelasticity, relaxation time, and phase transitions that mesoscopic fluid-like films undergo at solid-liquid interfaces, or under confinement between two sliding solid boundaries, constitutes one of the major challenges in condensed matter physics. Their role in the imaging process of solid substrates by scanning probe microscopy (SPM) is also currently controversial. Aiming at improving the reliability and versatility of instrumentation dedicated to characterize mesoscopic films, a noninvasive whispering-gallery acoustic sensing (WGAS) technique is introduced; its application as feedback control in SPM is also demonstrated. To illustrate its working principle and potential merits, WGAS has been integrated into a SPM that uses a sharp tip attached to an electrically driven 32-kHz piezoelectric tuning fork (TF), the latter also tighten to the operating microscope's frame. Such TF-based SPMs typically monitor the TF's state of motion by electrical means, hence subjected to the effects caused by the inherent capacitance of the device (i.e., electrical resonance differing from the probe's mechanical resonance). Instead, the novelty of WGAS resides in exploiting the already existent microscope's frame as an acoustic cavity (its few centimeter-sized perimeter closely matching the operating acoustic wavelength) where standing-waves (generated by the nanometer-sized oscillations of the TF's tines) are sensitively detected by an acoustic transducer (the latter judiciously placed around the microscope's frame perimeter for attaining maximum detection). This way, WGAS is able to remote monitoring, via acoustic means, the nanometer-sized amplitude motion of the TF's tines. (This remote-detection method resembles the ability to hear faint, but still clear, levels of sound at the galleries of a cathedral, despite the extraordinary distance location of the sound source.) In applications aiming at

  15. Imaging and quantitative data acquisition of biological cell walls with Atomic Force Microscopy and Scanning Acoustic Microscopy

    SciTech Connect

    Tittmann, B. R.; Xi, X.

    2014-09-01

    This chapter demonstrates the feasibility of Atomic Force Microscopy (AFM) and High Frequency Scanning Acoustic Microscopy (HF-SAM) as tools to characterize biological tissues. Both the AFM and the SAM have shown to provide imaging (with different resolution) and quantitative elasticity measuring abilities. Plant cell walls with minimal disturbance and under conditions of their native state have been examined with these two kinds of microscopy. After descriptions of both the SAM and AFM, their special features and the typical sample preparation is discussed. The sample preparation is focused here on epidermal peels of onion scales and celery epidermis cells which were sectioned for the AFM to visualize the inner surface (closest to the plasma membrane) of the outer epidermal wall. The nm-wide cellulose microfibrils orientation and multilayer structure were clearly observed. The microfibril orientation and alignment tend to be more organized in older scales compared with younger scales. The onion epidermis cell wall was also used as a test analog to study cell wall elasticity by the AFM nanoindentation and the SAM V(z) feature. The novelty in this work was to demonstrate the capability of these two techniques to analyze isolated, single layered plant cell walls in their natural state. AFM nanoindentation was also used to probe the effects of Ethylenediaminetetraacetic acid (EDTA), and calcium ion treatment to modify pectin networks in cell walls. The results suggest a significant modulus increase in the calcium ion treatment and a slight decrease in EDTA treatment. To complement the AFM measurements, the HF-SAM was used to obtain the V(z) signatures of the onion epidermis. These measurements were focused on documenting the effect of pectinase enzyme treatment. The results indicate a significant change in the V(z) signature curves with time into the enzyme treatment. Thus AFM and HF-SAM open the door to a systematic nondestructive structure and mechanical property

  16. A pilot study of scanning acoustic microscopy as a tool for measuring arterial stiffness in aortic biopsies

    PubMed Central

    Akhtar, Riaz; Cruickshank, J. Kennedy; Zhao, Xuegen; Derby, Brian; Weber, Thomas

    2016-01-01

    This study explores the use of scanning acoustic microscopy (SAM) as a potential tool for characterisation of arterial stiffness using aortic biopsies. SAM data is presented for human tissue collected during aortic bypass graft surgery for multi-vessel coronary artery disease. Acoustic wave speed as determined by SAM was compared to clinical data for the patients namely, pulse wave velocity (PWV), blood pressure, cholesterol and glucose levels. There was no obvious trend relating acoustic wave speed to PWV values, and an inverse relationship was found between systolic and diastolic blood pressure and acoustic wave speed. However, in patients with a higher cholesterol or glucose level, the acoustic wave speed increased. A more detailed investigation is needed to relate SAM data to clinical measurements. PMID:26985242

  17. CHARACTERIZING LOCALIZED STRAIN OF IN0.83Al0.17As/In0.83Ga0.17As DETECTOR USING LOW FREQUENCY ATOMIC FORCE ACOUSTIC MICROSCOPE

    NASA Astrophysics Data System (ADS)

    Su, Weitao; Dou, Honglei; Huo, Dexuan; Yu, Guolin; Dai, Ning

    2016-01-01

    Localized strain accumulation and related defects strongly affect the performance of optoelectronic detectors. However, characterizing distribution of the localized strain and defects still challenges usability and spatial resolution of many measurements. In current study, the defects and surface strain accumulation of In0.83Al0.17As/In0.83Ga0.17As multilayer detectors are investigated using low-frequency atomic force acoustic microscope (AFAM) and Raman spectroscopy. With AFAM, the strain accumulation and defects can be easily identified and measured with spatial resolution as good as that of atomic force microscope (AFM).

  18. Reliability of void detection in structural ceramics by use of scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Klima, S. J.; Kiser, J. D.; Baaklini, G. Y.

    1986-01-01

    The reliability of scanning laser acoustic microscopy (SLAM) for detecting surface voids in structural ceramic test specimens was statistically evaluated. Specimens of sintered silicon nitride and sintered silicon carbide, seeded with surface voids, were examined by SLAM at an ultrasonic frequency of 100 MHz in the as fired condition and after surface polishing. It was observed that polishing substantially increased void detectability. Voids as small as 100 micrometers in diameter were detected in polished specimens with 0.90 probability at a 0.95 confidence level. In addition, inspection times were reduced up to a factor of 10 after polishing. The applicability of the SLAM technique for detection of naturally occurring flaws of similar dimensions to the seeded voids is discussed. A FORTRAN program listing is given for calculating and plotting flaw detection statistics.

  19. Reliability of void detection in structural ceramics using scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Klima, S. J.; Kiser, J. D.; Baaklini, G. Y.

    1985-01-01

    The reliability of scanning laser acoustic microscopy (SLAM) for detecting surface voids in structural ceramic test specimens was statistically evaluated. Specimens of sintered silicon nitride and sintered silicon carbide, seeded with surface voids, were examined by SLAM at an ultrasonic frequency of 100 MHz in the as fired condition and after surface polishing. It was observed that polishing substantially increased void detectability. Voids as small as 100 micrometers in diameter were detected in polished specimens with 0.90 probability at a 0.95 confidence level. In addition, inspection times were reduced up to a factor of 10 after polishing. The applicability of the SLAM technique for detection of naturally occurring flaws of similar dimensions to the seeded voids is discussed. A FORTRAN program listing is given for calculating and plotting flaw detection statistics.

  20. Reliability of void detection in structural ceramics by use of scanning laser acoustic microscopy

    SciTech Connect

    Roth, D.J.; Klima, S.J.; Kiser, J.D.; Baaklini, G.Y.

    1986-05-01

    The reliability of scanning laser acoustic microscopy (SLAM) for detecting surface voids in structural ceramic test specimens was statistically evaluated. Specimens of sintered silicon nitride and sintered silicon carbide, seeded with surface voids, were examined by SLAM at an ultrasonic frequency of 100 MHz in the as fired condition and after surface polishing. It was observed that polishing substantially increased void detectability. Voids as small as 100 micrometers in diameter were detected in polished specimens with 0.90 probability at a 0.95 confidence level. In addition, inspection times were reduced up to a factor of 10 after polishing. The applicability of the SLAM technique for detection of naturally occurring flaws of similar dimensions to the seeded voids is discussed. A FORTRAN program listing is given for calculating and plotting flaw detection statistics. 20 references.

  1. Noncontact microrheology at acoustic frequencies using frequency-modulated atomic force microscopy.

    PubMed

    Gavara, Núria; Chadwick, Richard S

    2010-08-01

    We report an atomic force microscopy (AFM) method for assessing elastic and viscous properties of soft samples at acoustic frequencies under non-contact conditions. The method can be used to measure material properties via frequency modulation and is based on hydrodynamics theory of thin gaps we developed here. A cantilever with an attached microsphere is forced to oscillate tens of nanometers above a sample. The elastic modulus and viscosity of the sample are estimated by measuring the frequency-dependence of the phase lag between the oscillating microsphere and the driving piezo at various heights above the sample. This method features an effective area of pyramidal tips used in contact AFM but with only piconewton applied forces. Using this method, we analyzed polyacrylamide gels of different stiffness and assessed graded mechanical properties of guinea pig tectorial membrane. The technique enables the study of microrheology of biological tissues that produce or detect sound. PMID:20562866

  2. Scanning electron acoustic microscopy of indentation-induced cracks and residual stresses in ceramics

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Qian, Menglu; Ravichandran, M. V.; Knowles, K. M.

    1990-01-01

    The ability of scanning electron acoustic microscopy (SEAM) to characterize ceramic materials is assessed. SEAM images of Vickers indentations in SiC whisker-reinforced alumina clearly reveal not only the radial cracks, the length of which can be used to estimate the fracture toughness of the material, but also reveal strong contrast, interpreted as arising from the combined effects of lateral cracks and the residual stress field left in the SiC whisker-reinforced alumina by the indenter. The strong contrast is removed after the material is heat treated at 1000 C to relieve the residual stresses around the indentations. A comparison of these observations with SEAM and reflected polarized light observations of Vickers indentations in soda-lime glass both before and after heat treatment confirms the interpretation of the strong contrast.

  3. Scanning acoustic microscopy for characterization of neoplastic and inflammatory lesions of lymph nodes.

    PubMed

    Miura, Katsutoshi; Nasu, Hatsuko; Yamamoto, Seiji

    2013-01-01

    A scanning acoustic microscope (SAM) imaging system calculates and color codes speed of sound (SOS). We evaluated the SAM results for lymph node imaging and compared these results with those of light microscopy (LM). SAM showed normal structures and localized/diffuse lesions of the lymph node. Our results revealed that as a rule, soft areas such as cystic necrosis presented less SOS while harder areas such as coagulative necrosis, granulomas, and fibrosis exhibited greater SOS. SOS increased according to stromal desmoplastic reactions and cellular concentration. In neoplastic lesions, statistically significant differences in SOS were observed among scirrhous carcinomas, lymphomas, and medullary carcinomas. SAM provided the following benefits over LM: (1) images reflected the tissue elasticity of each lesion, (2) digitized SOS data could be statistically comparable, (3) images were acquired in a few minutes without special staining, (4) SAM images and echographic images were comparable for clinical ultrasound imaging study. PMID:23409246

  4. Amplitude modulation atomic force microscopy, is acoustic driving in liquid quantitatively reliable?

    PubMed

    Liu, Fei; Zhao, Cunlu; Mugele, Frieder; van den Ende, Dirk

    2015-09-25

    Measuring quantitative tip-sample interaction forces in dynamic atomic force microscopy in fluids is challenging because of the strong damping of the ambient viscous medium and the fluid-mediated driving forces. This holds in particular for the commonly used acoustic excitation of the cantilever oscillation. Here we present measurements of tip-sample interactions due to conservative DLVO and hydration forces and viscous dissipation forces in aqueous electrolytes using tips with radii varying from typical 20 nm for the DLVO and hydration forces, to 1 μm for the viscous dissipation. The measurements are analyzed using a simple harmonic oscillator model, continuous beam theory with fluid-mediated excitation and thermal noise spectroscopy (TNS). In all cases consistent conservative forces, deviating less than 40% from each other, are obtained for all three approaches. The DLVO forces are even within 5% of the theoretical expectations for all approaches. Accurate measurements of dissipative forces within 15% of the predictions of macroscopic fluid dynamics require the use of TNS or continuous beam theory including fluid-mediated driving. Taking this into account, acoustic driving in liquid is quantitatively reliable. PMID:26335613

  5. Amplitude modulation atomic force microscopy, is acoustic driving in liquid quantitatively reliable?

    NASA Astrophysics Data System (ADS)

    Liu, Fei; Zhao, Cunlu; Mugele, Frieder; van den Ende, Dirk

    2015-09-01

    Measuring quantitative tip-sample interaction forces in dynamic atomic force microscopy in fluids is challenging because of the strong damping of the ambient viscous medium and the fluid-mediated driving forces. This holds in particular for the commonly used acoustic excitation of the cantilever oscillation. Here we present measurements of tip-sample interactions due to conservative DLVO and hydration forces and viscous dissipation forces in aqueous electrolytes using tips with radii varying from typical 20 nm for the DLVO and hydration forces, to 1 μm for the viscous dissipation. The measurements are analyzed using a simple harmonic oscillator model, continuous beam theory with fluid-mediated excitation and thermal noise spectroscopy (TNS). In all cases consistent conservative forces, deviating less than 40% from each other, are obtained for all three approaches. The DLVO forces are even within 5% of the theoretical expectations for all approaches. Accurate measurements of dissipative forces within 15% of the predictions of macroscopic fluid dynamics require the use of TNS or continuous beam theory including fluid-mediated driving. Taking this into account, acoustic driving in liquid is quantitatively reliable.

  6. In vivo deconvolution acoustic-resolution photoacoustic microscopy in three dimensions

    PubMed Central

    Cai, De; Li, Zhongfei; Chen, Sung-Liang

    2016-01-01

    Acoustic-resolution photoacoustic microscopy (ARPAM) provides a spatial resolution on the order of tens of micrometers, and is becoming an essential tool for imaging fine structures, such as the subcutaneous microvasculature. High lateral resolution of ARPAM is achieved using high numerical aperture (NA) of acoustic transducer; however, the depth of focus and working distance will be deteriorated correspondingly, thus sacrificing the imaging range and accessible depth. The axial resolution of ARPAM is limited by the transducer’s bandwidth. In this work, we develop deconvolution ARPAM (D-ARPAM) in three dimensions that can improve the lateral resolution by 1.8 and 3.7 times and the axial resolution by 1.7 and 2.7 times, depending on the adopted criteria, using a 20-MHz focused transducer without physically increasing its NA and bandwidth. The resolution enhancement in three dimensions by D-ARPAM is also demonstrated by in vivo imaging of the microvasculature of a chick embryo. The proposed D-ARPAM has potential for biomedical imaging that simultaneously requires high spatial resolution, extended imaging range, and long accessible depth. PMID:26977346

  7. In vivo microscopy of targeted vessel occlusion employing acoustic droplet vaporization

    PubMed Central

    Samuel, Stanley; Duprey, Ambroise; Fabiilli, Mario L.; Bull, Joseph L.; Fowlkes, J. Brian

    2012-01-01

    Objective Embolotherapy is a potential means to treat a variety of cancers. Our approach – gas embolotherapy – introduces the droplets upstream from the tumor and then acoustically activates them to form bubbles for occlusion – a process known as acoustic droplet vaporization (ADV). We wanted to provide the first optical documentation of ADV, lodged bubbles, or vessel occlusion in vivo. Methods We used the rat cremaster muscle for in vivo microscopy. Perfluorocarbon droplets were administered into the aortic arch. Ultrasound exposures in the cremaster induced vaporization. The cremaster was examined pre- and post-exposure for ADV-related effects. Two sets of experiments compared the effect of exposure in the capillaries versus the first order arteriole. Results Bubbles that lodge following capillary exposure are significantly larger (76μm mean length, 36μm mean diameter) than those following feeder vessel exposure (25μm mean length, 11μm mean diameter). Despite the differing sizes in bubbles, the ratio of bubble length to the hydraulic diameter of all lodged bubbles was 2.11 (±0.65; N=112), which agrees with theoretical predictions and experimental observations. Conclusions Our results provide the first optical evidence of targeted vessel occlusion through ADV. These findings could lay the groundwork for the advancement of gas embolotherapy. PMID:22404846

  8. Atomic force acoustic microscopy: Influence of the lateral contact stiffness on the elastic measurements.

    PubMed

    Flores-Ruiz, F J; Espinoza-Beltrán, F J; Diliegros-Godines, C J; Siqueiros, J M; Herrera-Gómez, A

    2016-09-01

    Atomic force acoustic microscopy is a dynamic technique where the resonances of a cantilever, that has its tip in contact with the sample, are used to quantify local elastic properties of surfaces. Since the contact resonance frequencies (CRFs) monotonically increase with the tip-sample contact stiffness, they are used to evaluate the local elastic properties of the surfaces through a suitable contact mechanical model. The CRFs depends on both, normal and lateral contact stiffness, kN and kS respectively, where the last one is taken either as constant (kS<1), or as zero, leading to uncertainty in the estimation of the elastic properties of composite materials. In this work, resonance spectra for free and contact vibration were used in a finite element analysis of cantilevers to show the influence of kS in the resonance curves due to changes in the kS/kN ratio. These curves have regions for the different vibrational modes that are both, strongly and weakly dependent on kS, and they can be used in a selective manner to obtain a precise mapping of elastic properties. PMID:27428309

  9. Integrated optical- and acoustic-resolution photoacoustic microscopy based on an optical fiber bundle

    PubMed Central

    Maslov, Konstantin; Wang, Lihong V.

    2014-01-01

    Photoacoustic microscopy (PAM), whose spatial resolution and maximum imaging depth are both scalable, has made great progress in recent years. However, each PAM system currently achieves only one resolution with an associated maximum imaging depth. Here, we present an integrated optical-resolution (OR) and acoustic-resolution (AR) PAM system implemented by delivering light via an optical fiber bundle. A single fiber core is used to deliver light for OR illumination in order to achieve a small spot size and hence high lateral resolution, whereas all the fiber cores are used to deliver more energy for AR illumination. Most other components are shared by the OR and AR imaging. The lateral resolution can be seamlessly switched between 2.2 μm and 40 μm as the maximum imaging depth is switched between 1.3 mm and 3.0 mm. The system enables automatically co-registered higher-resolution OR and deeper AR photoacoustic imaging. PMID:23282835

  10. Determination of high burn-up nuclear fuel elastic properties with acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Laux, D.; Baron, D.; Despaux, G.; Kellerbauer, A. I.; Kinoshita, M.

    2012-01-01

    We report the measurement of elastic constants of non-irradiated UO 2, SIMFUEL (simulated spent fuel: UO 2 with several additives which aim to simulate the effect of burnup) and irradiated fuel by focused acoustic microscopy. To qualify the technique a parametric study was conducted by performing measurements on depleted uranium oxide (with various volume fraction of porosity, Oxygen-to-metal ratios, grain sizes) and SIMFUEL and by comparing them with previous works presented in the literature. Our approach was in line with existing literature for each parameter studied. It was shown that the main parameters influencing the elastic moduli are the amount of fission products in solution (related to burnup) and the pore density and shape, the influence of which has been evaluated. The other parameters (irradiation defects, oxygen-to-metal ratio and grain sizes) mainly increase the attenuation of the ultrasonic wave but do not change the wave velocity, which is used in the proposed method to evaluate Young's modulus. Measurements on irradiated fuel (HBRP and N118) were then performed. A global decrease of 25% of the elastic modulus between 0 and 100 GWd/tM was observed. This observation is compared to results obtained with measurements conducted at ITU by Knoop indentation techniques.

  11. High-power acoustic insult to living cultured cells as studied by high-frequency scanning acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Miyasaka, Chiaki; Tittmann, Bernhard R.

    2002-06-01

    A plurality of articles discussing combined effects of acoustic high-pressure (mechanical factor) and heat (thermal factor) caused by acoustic vibration on biological tissues and cells has been published. Herein, we contribute the preliminary results describing the behavior of living human skin cells when separately applying shock waves and thermal insult to them. First, we gradually increased temperature of a culturing medium from 37.5 to 52 degree(s)C using the heat plate with temperature controller, and carried out in-situ observation of the cells grown on a substrate via the medium using a scanning acoustic microscope. Second, we provided the pressure using high power ultrasonic pulses generated by a laser induced ultrasonic shock wave system to the cells, wherein the pressure caused by the pulses was measured by a hydrophone, and wherein temperature was monitored by thermocouples. The cells were observed just after giving the impact. The difference between phenomena indicating cellular insult and injury (e.g., shrinkage or lift-off) were clearly visualized by the scanning acoustic microscope with frequency at 1.0 GHz.

  12. Analytical Model of the Nonlinear Dynamics of Cantilever Tip-Sample Surface Interactions for Various Acoustic-Atomic Force Microscopies

    NASA Technical Reports Server (NTRS)

    Cantrell, John H., Jr.; Cantrell, Sean A.

    2008-01-01

    A comprehensive analytical model of the interaction of the cantilever tip of the atomic force microscope (AFM) with the sample surface is developed that accounts for the nonlinearity of the tip-surface interaction force. The interaction is modeled as a nonlinear spring coupled at opposite ends to linear springs representing cantilever and sample surface oscillators. The model leads to a pair of coupled nonlinear differential equations that are solved analytically using a standard iteration procedure. Solutions are obtained for the phase and amplitude signals generated by various acoustic-atomic force microscope (A-AFM) techniques including force modulation microscopy, atomic force acoustic microscopy, ultrasonic force microscopy, heterodyne force microscopy, resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM), and the commonly used intermittent contact mode (TappingMode) generally available on AFMs. The solutions are used to obtain a quantitative measure of image contrast resulting from variations in the Young modulus of the sample for the amplitude and phase images generated by the A-AFM techniques. Application of the model to RDF-AFUM and intermittent soft contact phase images of LaRC-cp2 polyimide polymer is discussed. The model predicts variations in the Young modulus of the material of 24 percent from the RDF-AFUM image and 18 percent from the intermittent soft contact image. Both predictions are in good agreement with the literature value of 21 percent obtained from independent, macroscopic measurements of sheet polymer material.

  13. Angular measurement of acoustic reflection coefficients by the inversion of V(z, t) data with high frequency time-resolved acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Bai, Xiaolong; Yang, Keji; Ju, Bing-Feng

    2012-01-01

    For inspection of mechanical properties and integrity of critical components such as integrated circuits or composite materials by acoustic methodology, it is imperative to evaluate their acoustic reflection coefficients, which are in close correlation with the elastic properties, thickness, density, and attenuation and interface adhesion of these layered structures. An experimental method based on angular spectrum to evaluate the acoustic coefficient as a function of the incident angle, θ, and frequency, ω, is presented with high frequency time-resolved acoustic microscopy. In order to achieve a high spatial resolution for evaluation of thin plates with thicknesses about one or two wavelengths, a point focusing transducer with a nominal center frequency of 25 MHz is adopted. By measuring the V(z, t) data in pulse mode, the reflection coefficient, R(θ, ω), can be reconstructed from its two-dimensional spectrum. It brings simplicity to experimental setup and measurement procedure since only single translation of the transducer in the vertical direction is competent for incident angle and frequency acquisition. It overcomes the disadvantages of the conventional methods requiring the spectroscopy for frequency scanning and/or ultrasonic goniometer for angular scanning. Two substrates of aluminum and Plexiglas and four stainless plates with various thicknesses of 100 μm, 150 μm, 200 μm, and 250 μm were applied. The acoustic reflection coefficients are consistent with the corresponding theoretical calculations. It opened the way of non-destructive methodology to evaluate the elastic and geometrical properties of very thin multi-layers structures simultaneously.

  14. Application of Acoustic Techniques for Characterization of Biological Samples

    NASA Astrophysics Data System (ADS)

    Tittmann, Bernhard R.; Ebert, Anne

    The atomic force microscope (AFM) is emerging as a powerful tool in cell biology. Originally developed for high-resolution imaging purposes, the AFM also has unique capabilities as a nano-indenter to probe the dynamic viscoelastic material properties of living cells in culture. In particular, AFM elastography combines imaging and indentation modalities to map the spatial distribution of cell mechanical properties, which in turn reflect the structure and function of the underlying cytoskeleton. Such measurements have contributed to our understanding of cell mechanics and cell biology and appear to be sensitive to the presence of disease in individual cells. Examples of applications and considerations on the effective capability of ultrasonic AFM techniques on biological samples (both mammalian and plant) are reported in this chapter. Included in the discussion is scanning near-field ultrasound holography an acoustic technique which has been used to image structure and in particular nanoparticles inside cells. For illustration an example that is discussed in some detail is a technique for rapid in vitro single-cell elastography. The technique is based on atomic force acoustic microscopy (AFAM) but (1) requires only a few minutes of scan time, (2) can be used on live cells briefly removed from most of the nutrient fluid, (3) does negligible harm or damage to the cell, (4) provides semi-quantitative information on the distribution of modulus across the cell, and (5) yields data with 1-10 nm resolution. The technique is shown to enable rapid assessment of physical/biochemical signals on the cell modulus and contributes to current understanding of cell mechanics.

  15. Characterization of mechanical properties of hybrid contrast agents by combining atomic force microscopy with acoustic/optic assessments.

    PubMed

    Guo, Gepu; Tu, Juan; Guo, Xiasheng; Huang, Pintong; Wu, Junru; Zhang, Dong

    2016-02-01

    Multi-parameter fitting algorithms, which are currently used for the characterization of coated-bubbles, inevitably introduce uncertainty into the results. Therefore, a better technique that can accurately determine the microbubbles׳ mechanical properties is urgently needed. A comprehensive technology combining atomic force microscopy, optical, and acoustic measurements with simulations of coated-bubble dynamics was developed. Using this technique, the mechanical parameters (size distribution, shell thickness, elasticity, and viscosity) of hybrid (ultrasound/magnetic-resonance-imaging) contrast microbubbles and their structure-property relationship were determined. The measurements indicate that when more superparamagnetic iron oxide nanoparticles are embedded in the microbubbles׳ shells, their mean diameter and effective viscosity increase, and their elastic modulus decreases. This reduces the microbubbles׳ resonance frequency and thus enhances acoustic scattering and attenuation effects. PMID:26726783

  16. Acoustics

    NASA Astrophysics Data System (ADS)

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

  17. Mechanical properties of single cells by high-frequency time-resolved acoustic microscopy.

    PubMed

    Weiss, Eike C; Anastasiadis, Pavlos; Pilarczyk, Götz; Lemor, Robert M; Zinin, Pavel V

    2007-11-01

    In this paper, we describe a new, high-frequency, time-resolved scanning acoustic microscope developed for studying dynamical processes in biological cells. The new acoustic microscope operates in a time-resolved mode. The center frequency is 0.86 GHz, and the pulse duration is 5 ns. With such a short pulse, layers thicker than 3 microm can be resolved. For a cell thicker than 3 microm, the front echo and the echo from the substrate can be distinguished in the signal. Positions of the first and second pulses are used to determine the local impedance of the cell modeled as a thin liquid layer that has spatial variations in its elastic properties. The low signal-to-noise ratio in the acoustical images is increased for image generation by averaging the detected radio frequency signal over 10 measurements at each scanning point. In conducting quantitative measurements of the acoustic parameters of cells, the signal can be averaged over 2000 measurements. This approach enables us to measure acoustical properties of a single HeLa cell in vivo and to derive elastic parameters of subcellular structures. The value of the sound velocity inside the cell (1534.5 +/- 33.6 m/s) appears to be only slightly higher than that of the cell medium (1501 m/s). PMID:18051160

  18. Characterization of acoustic lenses with the Foucault test by confocal laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Ahmed Mohamed, E. T.; Abdelrahman, A.; Pluta, M.; Grill, W.

    2010-03-01

    In this work, the Foucault knife-edge test, which has traditionally been known as the classic test for optical imaging devices, is used to characterize an acoustic lens for operation at 1.2 GHz. A confocal laser scanning microscope (CLSM) was used as the illumination and detection device utilizing its pinhole instead of the classical knife edge that is normally employed in the Foucault test. Information about the geometrical characteristics, such as the half opening angle of the acoustic lens, were determined as well as the quality of the calotte of the lens used for focusing. The smallest focal spot size that could be achieved with the examined lens employed as a spherical reflector was found to be about 1 μm. By comparison to the idealized resolution a degradation of about a factor of 2 can be deduced. This limits the actual quality of the acoustic focus.

  19. Visualization of subsurface nanoparticles in a polymer matrix using resonance tracking atomic force acoustic microscopy and contact resonance spectroscopy.

    PubMed

    Kimura, Kuniko; Kobayashi, Kei; Yao, Atsushi; Yamada, Hirofumi

    2016-10-14

    A visualization technique of subsurface features with a nanometer-scale spatial resolution is strongly demanded. Some research groups have demonstrated the visualization of subsurface features using various techniques based on atomic force microscopy. However, the imaging mechanisms have not yet been fully understood. In this study, we demonstrated the visualization of subsurface Au nanoparticles buried in a polymer matrix 900 nm from the surface using two techniques; i.e., resonance tracking atomic force acoustic microscopy and contact resonance spectroscopy. It was clarified that the subsurface features were visualized by the two techniques as the area with a higher contact resonance frequency and a higher Q-factor than those in the surrounding area, which suggests that the visualization is realized by the variation of the contact stiffness and damping of the polymer matrix due to the existence of the buried nanoparticles. PMID:27607548

  20. Scanning Acoustic Microscopy Investigation of Frequency-Dependent Reflectance of Acid-Etched Human Dentin Using Homotopic Measurements

    PubMed Central

    Marangos, Orestes; Misra, Anil; Spencer, Paulette; Katz, J. Lawrence

    2013-01-01

    Composite restorations in modern restorative dentistry rely on the bond formed in the adhesive-infiltrated acid-etched dentin. The physical characteristics of etched dentin are, therefore, of paramount interest. However, characterization of the acid-etched zone in its natural state is fraught with problems stemming from a variety of sources including its narrow size, the presence of water, heterogeneity, and spatial scale dependency. We have developed a novel homotopic (same location) measurement methodology utilizing scanning acoustic microscopy (SAM). Homotopic measurements with SAM overcome the problems encountered by other characterization/ imaging methods. These measurements provide us with acoustic reflectance at the same location of both the pre- and post-etched dentin in its natural state. We have applied this methodology for in vitro measurements on dentin samples. Fourier spectra from acid-etched dentin showed amplitude reduction and shifts of the central frequency that were location dependent. Through calibration, the acoustic reflectance of acid-etched dentin was found to have complex and non-monotonic frequency dependence. These data suggest that acid-etching of dentin results in a near-surface graded layer of varying thickness and property gradations. The measurement methodology described in this paper can be applied to systematically characterize mechanical properties of heterogeneous soft layers and interfaces in biological materials. PMID:21429849

  1. Evaluation of near-surface stress distributions in dissimilar welded joint by scanning acoustic microscopy.

    PubMed

    Kwak, Dong Ryul; Yoshida, Sanichiro; Sasaki, Tomohiro; Todd, Judith A; Park, Ik Keun

    2016-04-01

    This paper presents the results from a set of experiments designed to ultrasonically measure the near surface stresses distributed within a dissimilar metal welded plate. A scanning acoustic microscope (SAM), with a tone-burst ultrasonic wave frequency of 200 MHz, was used for the measurement of near surface stresses in the dissimilar welded plate between 304 stainless steel and low carbon steel. For quantitative data acquisition such as leaky surface acoustic wave (leaky SAW) velocity measurement, a point focus acoustic lens of frequency 200 MHz was used and the leaky SAW velocities within the specimen were precisely measured. The distributions of the surface acoustic wave velocities change according to the near-surface stresses within the joint. A three dimensional (3D) finite element simulation was carried out to predict numerically the stress distributions and compare with the experimental results. The experiment and FE simulation results for the dissimilar welded plate showed good agreement. This research demonstrates that a combination of FE simulation and ultrasonic stress measurements using SAW velocity distributions appear promising for determining welding residual stresses in dissimilar material joints. PMID:26773788

  2. Numerical and experimental analysis of high frequency acoustic microscopy and infrared reflectance system for early detection of melanoma

    NASA Astrophysics Data System (ADS)

    Karagiannis, Georgios; Apostolidis, Georgios; Georgoulias, Panagiotis

    2016-03-01

    Melanoma is a very malicious type of cancer as it metastasizes early and hence its late diagnosis leads to death. Consequently, early diagnosis of melanoma and its removal is considered the most effective way of treatment. We present a design of a high frequency acoustic microscopy and infrared reflectance system for the early detection of melanoma. Specifically, the identification of morphological changes related to carcinogenesis is required. In this work, we simulate of the propagation of the ultrasonic waves of the order of 100 MHz as well as of electromagnetic waves of the order of 100 THz in melanoma structures targeting to the estimation and optimization of the basic characteristics of the systems. The simulation results of the acoustic microscopy subsystem aim to provide information such as the geometry of the transducer, the center frequency of operation, the focal length where the power transmittance is optimum and the spot size in focal length. As far as the infrared is concerned the optimal frequency range and the spot illumination size of the external probe is provided. This information is next used to assemble a properly designed system which is applied to melanoma phantoms as well as real skin lesions. Finally, the measurement data are visualized to reveal the information of the experimented structures, proving noteworthy accuracy.

  3. Acoustics

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

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

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

    SciTech Connect

    Achenbach, J.D.; Li, W.

    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.

  5. Scanning Acoustic Microscopy-A Novel Noninvasive Method to Determine Tumor Interstitial Fluid Pressure in a Xenograft Tumor Model.

    PubMed

    Hofmann, Matthias; Pflanzer, Ralph; Habib, Anowarul; Shelke, Amit; Bereiter-Hahn, Jürgen; Bernd, August; Kaufmann, Roland; Sader, Robert; Kippenberger, Stefan

    2016-06-01

    Elevated tumor interstitial fluid pressure (TIFP) is a prominent feature of solid tumors and hampers the transmigration of therapeutic macromolecules, for example, large monoclonal antibodies, from tumor-supplying vessels into the tumor interstitium. TIFP values of up to 40 mm Hg have been measured in experimental solid tumors using two conventional invasive techniques: the wick-in-needle and the micropuncture technique. We propose a novel noninvasive method of determining TIFP via ultrasonic investigation with scanning acoustic microscopy at 30-MHz frequency. In our experimental setup, we observed for the impedance fluctuations in the outer tumor hull of A431-vulva carcinoma-derived tumor xenograft mice. The gain dependence of signal strength was quantified, and the relaxation of tissue was calibrated with simultaneous hydrostatic pressure measurements. Signal patterns from the acoustical images were translated into TIFP curves, and a putative saturation effect was found for tumor pressures larger than 3 mm Hg. This is the first noninvasive approach to determine TIFP values in tumors. This technique can provide a potentially promising noninvasive assessment of TIFP and, therefore, can be used to determine the TIFP before treatment approach as well to measure therapeutic efficacy highlighted by lowered TFP values. PMID:27267834

  6. Imaging Acoustic Phonon Dynamics on the Nanometer-Femtosecond Spatiotemporal Length-Scale with Ultrafast Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Plemmons, Dayne; Flannigan, David

    Coherent collective lattice oscillations known as phonons dictate a broad range of physical observables in condensed matter and act as primary energy carriers across a wide range of material systems. Despite this omnipresence, analysis of phonon dynamics on their ultrashort native spatiotemporal length scale - that is, the combined nanometer (nm), spatial and femtosecond (fs), temporal length-scales - has largely remained experimentally inaccessible. Here, we employ ultrafast electron microscopy (UEM) to directly image discrete acoustic phonons in real-space with combined nm-fs resolution. By directly probing electron scattering in the image plane (as opposed to the diffraction plane), we retain phase information critical for following the evolution, propagation, scattering, and decay of phonons in relation to morphological features of the specimen (i.e. interfaces, grain boundaries, voids, ripples, etc.). We extract a variety of morphologically-specific quantitative information from the UEM videos including phonon frequencies, phase velocities, and decays times. We expect these direct manifestations of local elastic properties in the vicinity of material defects and interfaces will aide in the understanding and application of phonon-mediated phenomena in nanostructures. Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA.

  7. Measuring elastic properties of cells by evaluation of scanning acoustic microscopy V(Z) values using simplex algorithm

    PubMed Central

    Kundu, T.; Bereiter-Hahn, J.; Hillmann, K.

    1991-01-01

    In this paper a new technique is proposed to determine the acoustic properties as well as the thickness (and volume) of biological cells. Variations of thickness, density, acoustic wave velocity, stiffness, and attenuation coefficient of a living or dead cell are obtained by scanning the cell by an acoustic microscope. The distance between the cell and the microscope lens is varied and several voltage curves are thus obtained. These curves are then inverted by simplex optimization technique to obtain the cell parameters. The spatial resolution of the method is limited to the resolution of the scanning acoustic microscope. It allows to take advantage of the full range of frequencies and amplification of the microscope. Characteristic distributions of stiffness are exemplified with an endothelial cell in culture. The main part of the thin, lamellar cytoplasm has high stiffness, which drops close to the lamella/cell body transition region and only slightly increases again through the central part of the cell. Acoustic attenuation seems to be related to two factors, cytoplasm accumulation (in the lamellar parts) and scattering in the central part rich in organelles. ImagesFIGURE 10 PMID:19431793

  8. Electroless deposition of metallic silver from a choline chloride-based ionic liquid: a study using acoustic impedance spectroscopy, SEM and atomic force microscopy.

    PubMed

    Abbott, Andrew P; Nandhra, Satvinder; Postlethwaite, Stella; Smith, Emma L; Ryder, Karl S

    2007-07-28

    In this paper, we describe the first example of a sustained galvanic coating deposited on a surface from a non-aqueous liquid. We present the surface characterization of electroless silver deposits on copper substrates from a solution of Ag(+) ions in an ionic liquid based on a choline chloride (ChCl) eutectic. Through a study of these deposits and the mechanism of formation using acoustic impedance spectroscopy (QCM), probe microscopy (AFM) and electron microscopy (SEM/EDX), we demonstrate that sustained growth of the silver deposit is facilitated by the porous nature of the silver. This is in contrast to the dip-coating reaction of silver ions in aqueous media, where the reaction stops when surface coverage is reached. Electroless silver deposits of up to several microns have been obtained by dip coating in ionic liquids without the use of catalysts of strong inorganic acids. PMID:17622408

  9. Void-free Au-Sn eutectic bonding of GaAs dice and its characterization using scanning acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Matljasevic, Goran; Lee, Chin C.

    1989-03-01

    A new technique to produce perfect bonding between GaAs dice and alumina substrates is reported. Utilizing this technique, void-free bondings have been achieved consistently. The quality of the bonded devices is confirmed by a Scanning Acoustic Microscope (SAM) having a spatial resolution of 25 µm. Thermal cycling between -25° C and 125° C, and thermal shock between -196° C and 135° C, have been used to assess the reliability of the specimens. The SAM was used to study the variation of the bonds in the tests. After the tests, the bonds show no sign of degradation and the GaAs dice did not crack. Shear test has also been performed. All the well bonded specimens passed the shear test. The shear strength correlated very well with the SAM images of the specimens taken before the test.

  10. Analysis of residual stress in the resin of metal-resin adhesion structures by scanning acoustic microscopy.

    PubMed

    Ohno, Hiroki; Endo, Kazuhiko; Nagano-Takebe, Futami; Ida, Yusuke; Kakino, Ken; Narita, Toshio

    2013-01-01

    The residual stress caused by polymerization shrinkage and thermal contraction of a heat-curing resin containing 4-META on a metal-resin structure was measured by a scanning acoustic microscope. The tensile residual stress in the resin occurred within 70 µm of the adhesion interface with a flat plate specimen. The maximum tensile stress was about 58 MPa at the interface. On a metal plate specimen with retention holes, ring-like cracks in the resin occurred around the retention holes with the adhesive specimen and many linear cracks occurred in the resin vertical to the longitudinal direction of the metal frame with the non-adhesive specimens. There was tensile residual stress on the resin surface at the center of the retention holes of the adhesion specimen, indicating that the stress in the specimen with surface treatment for adhesion was higher than in that without surface treatment. PMID:24240901

  11. Photoacoustic Microscopy

    PubMed Central

    Yao, Junjie; Wang, Lihong V.

    2012-01-01

    Photoacoustic microscopy (PAM) is a hybrid in vivo imaging technique that acoustically detects optical contrast via the photoacoustic effect. Unlike pure optical microscopic techniques, PAM takes advantage of the weak acoustic scattering in tissue and thus breaks through the optical diffusion limit (~1 mm in soft tissue). With its excellent scalability, PAM can provide high-resolution images at desired maximum imaging depths up to a few millimeters. Compared with backscattering-based confocal microscopy and optical coherence tomography, PAM provides absorption contrast instead of scattering contrast. Furthermore, PAM can image more molecules, endogenous or exogenous, at their absorbing wavelengths than fluorescence-based methods, such as wide-field, confocal, and multi-photon microscopy. Most importantly, PAM can simultaneously image anatomical, functional, molecular, flow dynamic and metabolic contrasts in vivo. Focusing on state-of-the-art developments in PAM, this Review discusses the key features of PAM implementations and their applications in biomedical studies. PMID:24416085

  12. Acoustic neuroma

    MedlinePlus

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

  13. Acoustic Neuroma

    MedlinePlus

    An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...

  14. Acoustic Seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

    The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

  15. Acoustic seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

    The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

  16. Topological Acoustics

    NASA Astrophysics Data System (ADS)

    Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

    2015-03-01

    The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers.

  17. Topological acoustics.

    PubMed

    Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

    2015-03-20

    The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers. PMID:25839273

  18. Acoustic neuroma

    MedlinePlus

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

  19. Pure optical photoacoustic microscopy

    PubMed Central

    Xie, Zhixing; Chen, Sung-Liang; Ling, Tao; Guo, L. Jay; Carson, Paul L.; Wang, Xueding

    2011-01-01

    The concept of pure optical photoacoustic microscopy(POPAM) was proposed based on optical rastering of a focused excitation beam and optically sensing the photoacoustic signal using a microring resonator fabricated by a nanoimprinting technique. After the refinements of the microring’s working wavelength and in the resonator structure and mold fabrication, an ultrahigh Q factor of 3.0×105 was achieved which provided high sensitivity with a noise equivalent detectable pressure(NEDP) value of 29Pa. This NEDP is much lower than the hundreds of Pascals achieved with existing optical resonant structures such as etalons, fiber gratings and dielectric multilayer interference filters available for acoustic measurement. The featured high sensitivity allowed the microring resonator to detect the weak photoacoustic signals from micro- or submicroscale objects. The inherent superbroad bandwidth of the optical microring resonator combined with an optically focused scanning beam provided POPAM with high resolution in the axial as well as both lateral directions while the axial resolution of conventional photoacoustic microscopy (PAM) suffers from the limited bandwidth of PZT detectors. Furthermore, the broadband microring resonator showed similar sensitivity to that of our most sensitive PZT detector. The current POPAM system provides a lateral resolution of 5 μm and an axial resolution of 8 μm, comparable to that achieved by optical microscopy while presenting the unique contrast of optical absorption and functional information complementing other optical modalities. The 3D structure of microvasculature, including capillary networks, and even individual red blood cells have been discerned successfully in the proof-of-concept experiments on mouse bladders ex vivo and mouse ears in vivo. The potential of approximately GHz bandwidth of the microring resonator also might allow much higher resolution than shown here in microscopy of optical absorption and acoustic propagation

  20. Musical Acoustics

    NASA Astrophysics Data System (ADS)

    Gough, Colin

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

  1. Fluorescence Microscopy

    PubMed Central

    Sanderson, Michael J.; Smith, Ian; Parker, Ian; Bootman, Martin D.

    2016-01-01

    Fluorescence microscopy is a major tool with which to monitor cell physiology. Although the concepts of fluorescence and its optical separation using filters remain similar, microscope design varies with the aim of increasing image contrast and spatial resolution. The basics of wide-field microscopy are outlined to emphasize the selection, advantages, and correct use of laser scanning confocal microscopy, two-photon microscopy, scanning disk confocal microscopy, total internal reflection, and super-resolution microscopy. In addition, the principles of how these microscopes form images are reviewed to appreciate their capabilities, limitations, and constraints for operation. PMID:25275114

  2. Electron Microscopy.

    ERIC Educational Resources Information Center

    Beer, Michael

    1980-01-01

    Reviews technical aspects of structure determination in biological electron microscopy (EM). Discusses low dose EM, low temperature microscopy, electron energy loss spectra, determination of mass or molecular weight, and EM of labeled systems. Cites 34 references. (CS)

  3. Room Acoustics

    NASA Astrophysics Data System (ADS)

    Kuttruff, Heinrich; Mommertz, Eckard

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

  4. Acoustic Neuroma

    MedlinePlus

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

  5. Underwater Acoustics

    NASA Astrophysics Data System (ADS)

    Kuperman, William A.; Roux, Philippe

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

  6. Analytical Microscopy

    SciTech Connect

    Not Available

    2006-06-01

    In the Analytical Microscopy group, within the National Center for Photovoltaic's Measurements and Characterization Division, we combine two complementary areas of analytical microscopy--electron microscopy and proximal-probe techniques--and use a variety of state-of-the-art imaging and analytical tools. We also design and build custom instrumentation and develop novel techniques that provide unique capabilities for studying materials and devices. In our work, we collaborate with you to solve materials- and device-related R&D problems. This sheet summarizes the uses and features of four major tools: transmission electron microscopy, scanning electron microscopy, the dual-beam focused-ion-beam workstation, and scanning probe microscopy.

  7. SEISMIC AND ROCK PHYSICS DIAGNOSTICS OF MULTISCALE RESERVOIR TEXTURES

    SciTech Connect

    Gary Mavko

    2002-05-01

    As part of our study on ''Relationships between seismic properties and rock microstructure'', we have studied (1) How to quantify elastic properties of clay minerals using Atomic Force Acoustic Microscopy. We show how bulk modulus of clay can be measured using atomic force acoustic microscopy (AFAM) (2) We have successfully measured elastic properties of unconsolidated sediments in an effort to quantify attributes for detection of overpressures from seismic (3) We have initiated efforts for velocity upscaling to quantify long-wavelength and short-wavelength velocity behavior and the scale-dependent dispersion caused by sediment variability in different depositional environments.

  8. Acoustic biosensors

    PubMed Central

    Fogel, Ronen; Seshia, Ashwin A.

    2016-01-01

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. PMID:27365040

  9. Acoustic biosensors.

    PubMed

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

    2016-06-30

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. PMID:27365040

  10. Correlative Microscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microscopy and Imaging offers many opportunities to collaborate and cooperate with scientists in many different fields nationally and internationally. Images have proven to be very important components in basic research, product development and understanding structure/function relationships in addit...

  11. Correlative microscopy.

    PubMed

    Loussert Fonta, Céline; Humbel, Bruno M

    2015-09-01

    In recent years correlative microscopy, combining the power and advantages of different imaging system, e.g., light, electrons, X-ray, NMR, etc., has become an important tool for biomedical research. Among all the possible combinations of techniques, light and electron microscopy, have made an especially big step forward and are being implemented in more and more research labs. Electron microscopy profits from the high spatial resolution, the direct recognition of the cellular ultrastructure and identification of the organelles. It, however, has two severe limitations: the restricted field of view and the fact that no live imaging can be done. On the other hand light microscopy has the advantage of live imaging, following a fluorescently tagged molecule in real time and at lower magnifications the large field of view facilitates the identification and location of sparse individual cells in a large context, e.g., tissue. The combination of these two imaging techniques appears to be a valuable approach to dissect biological events at a submicrometer level. Light microscopy can be used to follow a labelled protein of interest, or a visible organelle such as mitochondria, in time, then the sample is fixed and the exactly same region is investigated by electron microscopy. The time resolution is dependent on the speed of penetration and fixation when chemical fixatives are used and on the reaction time of the operator for cryo-fixation. Light microscopy can also be used to identify cells of interest, e.g., a special cell type in tissue or cells that have been modified by either transfections or RNAi, in a large population of non-modified cells. A further application is to find fluorescence labels in cells on a large section to reduce searching time in the electron microscope. Multiple fluorescence labelling of a series of sections can be correlated with the ultrastructure of the individual sections to get 3D information of the distribution of the marked proteins: array

  12. Medical Acoustics

    NASA Astrophysics Data System (ADS)

    Beach, Kirk; Dunmire, Barbrina

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

  13. Acoustic chaos

    SciTech Connect

    Lauterborn, W.; Parlitz, U.; Holzfuss, J.; Billo, A.; Akhatov, I.

    1996-06-01

    Acoustic cavitation, a complex, spatio-temporal dynamical system, is investigated with respect to its chaotic properties. The sound output, the {open_quote}{open_quote}noise{close_quote}{close_quote}, is subjected to time series analysis. The spatial dynamics of the bubble filaments is captured by high speed holographic cinematography and subsequent digital picture processing from the holograms. Theoretical models are put forward for describing the pattern formation. {copyright} {ital 1996 American Institute of Physics.}

  14. Expansion Microscopy

    PubMed Central

    Chen, Fei; Tillberg, Paul W.; Boyden, Edward S.

    2014-01-01

    In optical microscopy, fine structural details are resolved by using refraction to magnify images of a specimen. Here we report the discovery that, by synthesizing a swellable polymer network within a specimen, it can be physically expanded, resulting in physical magnification. By covalently anchoring specific labels located within the specimen directly to the polymer network, labels spaced closer than the optical diffraction limit can be isotropically separated and optically resolved, a process we call expansion microscopy (ExM). Thus, this process can be used to perform scalable super-resolution microscopy with diffraction-limited microscopes. We demonstrate ExM with effective ~70 nm lateral resolution in both cultured cells and brain tissue, performing three-color super-resolution imaging of ~107 μm3 of the mouse hippocampus with a conventional confocal microscope. PMID:25592419

  15. Intravital microscopy

    PubMed Central

    Masedunskas, Andrius; Milberg, Oleg; Porat-Shliom, Natalie; Sramkova, Monika; Wigand, Tim; Amornphimoltham, Panomwat; Weigert, Roberto

    2012-01-01

    Intravital microscopy is an extremely powerful tool that enables imaging several biological processes in live animals. Recently, the ability to image subcellular structures in several organs combined with the development of sophisticated genetic tools has made possible extending this approach to investigate several aspects of cell biology. Here we provide a general overview of intravital microscopy with the goal of highlighting its potential and challenges. Specifically, this review is geared toward researchers that are new to intravital microscopy and focuses on practical aspects of carrying out imaging in live animals. Here we share the know-how that comes from first-hand experience, including topics such as choosing the right imaging platform and modality, surgery and stabilization techniques, anesthesia and temperature control. Moreover, we highlight some of the approaches that facilitate subcellular imaging in live animals by providing numerous examples of imaging selected organelles and the actin cytoskeleton in multiple organs. PMID:22992750

  16. Sensitivity of photoacoustic microscopy

    PubMed Central

    Yao, Junjie; Wang, Lihong V.

    2014-01-01

    Building on its high spatial resolution, deep penetration depth and excellent image contrast, 3D photoacoustic microscopy (PAM) has grown tremendously since its first publication in 2005. Integrating optical excitation and acoustic detection, PAM has broken through both the optical diffusion and optical diffraction limits. PAM has 100% relative sensitivity to optical absorption (i.e., a given percentage change in the optical absorption coefficient yields the same percentage change in the photoacoustic amplitude), and its ultimate detection sensitivity is limited only by thermal noise. Focusing on the engineering aspects of PAM, this Review discusses the detection sensitivity of PAM, compares the detection efficiency of different PAM designs, and summarizes the imaging performance of various endogenous and exogenous contrast agents. It then describes representative PAM applications with high detection sensitivity, and outlines paths to further improvement. PMID:25302158

  17. Acoustic Tooth Cleaner

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.

    1984-01-01

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

  18. Positron microscopy

    SciTech Connect

    Hulett, L.D. Jr.; Xu, J.

    1995-02-01

    The negative work function property that some materials have for positrons make possible the development of positron reemission microscopy (PRM). Because of the low energies with which the positrons are emitted, some unique applications, such as the imaging of defects, can be made. The history of the concept of PRM, and its present state of development will be reviewed. The potential of positron microprobe techniques will be discussed also.

  19. Acoustic transducer

    DOEpatents

    Drumheller, D.S.

    1997-12-30

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

  20. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S.

    1997-01-01

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

  1. Endoscopic Microscopy

    PubMed Central

    Sokolov, Konstantin; Sung, Kung-Bin; Collier, Tom; Clark, Anne; Arifler, Dizem; Lacy, Alicia; Descour, Michael; Richards-Kortum, Rebecca

    2002-01-01

    In vivo endoscopic optical microscopy provides a tool to assess tissue architecture and morphology with contrast and resolution similar to that provided by standard histopathology – without need for physical tissue removal. In this article, we focus on optical imaging technologies that have the potential to dramatically improve the detection, prevention, and therapy of epithelial cancers. Epithelial pre-cancers and cancers are associated with a variety of morphologic, architectural, and molecular changes, which currently can be assessed only through invasive, painful biopsy. Optical imaging is ideally suited to detecting cancer-related alterations because it can detect biochemical and morphologic alterations with sub-cellular resolution throughout the entire epithelial thickness. Optical techniques can be implemented non-invasively, in real time, and at low cost to survey the tissue surface at risk. Our manuscript focuses primarily on modalities that currently are the most developed: reflectance confocal microscopy (RCM) and optical coherence tomography (OCT). However, recent advances in fluorescence-based endoscopic microscopy also are reviewed briefly. We discuss the basic principles of these emerging technologies and their current and potential applications in early cancer detection. We also present research activities focused on development of exogenous contrast agents that can enhance the morphological features important for cancer detection and that have the potential to allow vital molecular imaging of cancer-related biomarkers. In conclusion, we discuss future improvements to the technology needed to develop robust clinical devices. PMID:14646041

  2. Acoustic cryocooler

    DOEpatents

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

    1990-01-01

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

  3. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S.

    2000-01-01

    An active acoustic transducer tool for use down-hole applications. The tool includes a single cylindrical mandrel including a shoulder defining the boundary of a narrowed portion over which is placed a sandwich-style piezoelectric tranducer assembly. The piezoelectric transducer assembly is prestressed by being placed in a thermal interference fit between the shoulder of the mandrel and the base of an anvil which is likewise positioned over the narrower portion of the mandrel. In the preferred embodiment, assembly of the tool is accomplished using a hydraulic jack to stretch the mandrel prior to emplacement of the cylindrical sandwich-style piezoelectric transducer assembly and anvil. After those elements are positioned and secured, the stretched mandrel is allowed to return substantially to its original (pre-stretch) dimensions with the result that the piezoelectric transducer elements are compressed between the anvil and the shoulder of the mandrel.

  4. Acoustic hemostasis

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

  5. Off-Axis Photoacoustic Microscopy

    PubMed Central

    Shelton, Ryan L.

    2016-01-01

    Photoacoustic microscopy (PAM) is a high-contrast, high-resolution imaging modality, used primarily for imaging hemoglobin and melanin. Important applications include mapping of the microvasculature and melanoma tumor margins. We demonstrate a novel PAM design that markedly simplifies the implementation by separating the optical illumination from the acoustic detection path. This modification enables the use of high-quality commercial optics and transducers, and may be readily adapted to commercial light microscopes. The designed PAM system is only sensitive to signals generated in the overlap of the illumination and detection solid angles, providing the additional benefit of quasi-dark-field detection. An off-axis PAM system with a lateral resolution of 26 μm and a modest axial resolution of 410 μm has been assembled and characterized using tissue samples. The axial resolution is readily scaled down to tens of micrometers within the same design, by utilizing commercially available high-frequency acoustic transducers. PMID:20176531

  6. Off-axis photoacoustic microscopy.

    PubMed

    Shelton, Ryan L; Applegate, Brian E

    2010-08-01

    Photoacoustic microscopy (PAM) is a high-contrast, high-resolution imaging modality, used primarily for imaging hemoglobin and melanin. Important applications include mapping of the microvasculature and melanoma tumor margins. We demonstrate a novel PAM design that markedly simplifies the implementation by separating the optical illumination from the acoustic detection path. This modification enables the use of high-quality commercial optics and transducers, and may be readily adapted to commercial light microscopes. The designed PAM system is only sensitive to signals generated in the overlap of the illumination and detection solid angles, providing the additional benefit of quasi-dark-field detection. An off-axis PAM system with a lateral resolution of 26 microm and a modest axial resolution of 410 microm has been assembled and characterized using tissue samples. The axial resolution is readily scaled down to tens of micrometers within the same design, by utilizing commercially available high-frequency acoustic transducers. PMID:20176531

  7. Acoustic telemetry.

    SciTech Connect

    Drumheller, Douglas Schaeffer; Kuszmaul, Scott S.

    2003-08-01

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

  8. The Sounds of Nanoscience: Acoustic STM Analogues

    ERIC Educational Resources Information Center

    Euler, Manfred

    2013-01-01

    A hands-on model of scanning tunnelling microscopy (STM) is presented. It uses near-field imaging with sound and computer assisted visualization to create acoustic mappings of resonator arrangements. Due to the (partial) analogy of matter and sound waves the images closely resemble STM scans of atoms. Moreover, the method can be extended to build…

  9. Domain characterization of Pb(Zn1/3Nb2/3)O3-(6%-7%)PbTiO3 single crystals using scanning electron acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Wong, Meng Fei; Heng, Xiangxin; Zeng, Kaiyang

    2008-10-01

    Domain structures of [001]T and [011]T-cut Pb(Zn1/3Nb2/3)O3-(6%-7%)PbTiO3 (PZN-PT) single crystals are studied using scanning electron acoustic microscope (SEAM) technique. The observation of the orientation of domain walls agree reasonably well with the trigonometric projection of rhombohedral and orthorhombic dipoles on the (001) and (011) surfaces, respectively. After mechanical loading with microindentation, domain switching is also observed to form a hyperbolic butterfly shape and extend preferentially along four diagonal directions, i.e., ⟨110⟩ on (001) surface and ⟨111¯⟩ on (011) surface. The critical shear stress to cause domain switching for PZN-PT crystal is estimated to be approximately 49 MPa for both {110} and {111¯} planes based on theoretical analysis. Generally, the SEAM technique has been successfully demonstrated to be a valid technique for observation of domain structures in single crystal PZN-PTs.

  10. Acoustic hemostasis

    NASA Astrophysics Data System (ADS)

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

    2000-07-01

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

  11. Acoustic source for generating an acoustic beam

    DOEpatents

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

    2016-05-31

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

  12. Acoustic Holography

    NASA Astrophysics Data System (ADS)

    Kim, Yang-Hann

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

  13. Acoustic Holography

    NASA Astrophysics Data System (ADS)

    Kim, Yang-Hann

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

  14. What Is an Acoustic Neuroma

    MedlinePlus

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

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

    NASA Astrophysics Data System (ADS)

    Shen, Jian Qi

    2016-08-01

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

  16. Symptoms of Acoustic Neuroma

    MedlinePlus

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

  17. Acoustic emission frequency discrimination

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  18. Tutorial on architectural acoustics

    NASA Astrophysics Data System (ADS)

    Shaw, Neil; Talaske, Rick; Bistafa, Sylvio

    2002-11-01

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

  19. AST Launch Vehicle Acoustics

    NASA Technical Reports Server (NTRS)

    Houston, Janice; Counter, D.; Giacomoni, D.

    2015-01-01

    The liftoff phase induces acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are then used in the prediction of internal vibration responses of the vehicle and components which result in the qualification levels. Thus, predicting these liftoff acoustic (LOA) environments is critical to the design requirements of any launch vehicle. If there is a significant amount of uncertainty in the predictions or if acoustic mitigation options must be implemented, a subscale acoustic test is a feasible pre-launch test option to verify the LOA environments. The NASA Space Launch System (SLS) program initiated the Scale Model Acoustic Test (SMAT) to verify the predicted SLS LOA environments and to determine the acoustic reduction with an above deck water sound suppression system. The SMAT was conducted at Marshall Space Flight Center and the test article included a 5% scale SLS vehicle model, tower and Mobile Launcher. Acoustic and pressure data were measured by approximately 250 instruments. The SMAT liftoff acoustic results are presented, findings are discussed and a comparison is shown to the Ares I Scale Model Acoustic Test (ASMAT) results.

  20. Acoustic Translation of an Acoustically Levitated Sample

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    Acoustic-levitation apparatus uses only one acoustic mode to move sample from one region of chamber to another. Sample heated and cooled quickly by translation between hot and cold regions of levitation chamber. Levitated sample is raised into furnace region by raising plunger. Frequency of sound produced by transducers adjusted by feedback system to maintain (102) resonant mode, which levitates sample midway between transducers and plunger regardless of plunger position.

  1. Nonlinear Acoustics in Fluids

    NASA Astrophysics Data System (ADS)

    Lauterborn, Werner; Kurz, Thomas; Akhatov, Iskander

    At high sound intensities or long propagation distances at in fluids sufficiently low damping acoustic phenomena become nonlinear. This chapter focuses on nonlinear acoustic wave properties in gases and liquids. The origin of nonlinearity, equations of state, simple nonlinear waves, nonlinear acoustic wave equations, shock-wave formation, and interaction of waves are presented and discussed. Tables are given for the nonlinearity parameter B/A for water and a range of organic liquids, liquid metals and gases. Acoustic cavitation with its nonlinear bubble oscillations, pattern formation and sonoluminescence (light from sound) are modern examples of nonlinear acoustics. The language of nonlinear dynamics needed for understanding chaotic dynamics and acoustic chaotic systems is introduced.

  2. Localized acoustic surface modes

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  3. Low frequency acoustic microscope

    DOEpatents

    Khuri-Yakub, Butrus T.

    1986-11-04

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

  4. Acoustic dispersive prism.

    PubMed

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

    2016-01-01

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

  5. Acoustic dispersive prism

    PubMed Central

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

    2016-01-01

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

  6. Acoustic dispersive prism

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  7. Note: Direct piezoelectric effect microscopy

    NASA Astrophysics Data System (ADS)

    Mori, T. J. A.; Stamenov, P.; Dorneles, L. S.

    2015-07-01

    An alternative method for investigating piezoelectric surfaces is suggested, exploiting the direct piezoeffect. The technique relies on acoustic (ultrasonic) excitation of the imaged surface and mapping of the resulting oscillatory electric potential. The main advantages arise from the spatial resolution of the conductive scanning probe microscopy in combination with the relatively large magnitude of the forward piezo signal Upf, which can be of the order of tens of mV even for non-ferroelectric piezoelectric materials. The potency of this experimental strategy is illustrated with measurements on well-crystallized quartz surfaces, where Upf ˜ 50 mV, for a piezoelectric coefficient of d33 = - 2.27 × 10-12 m/V, and applied stress of about T3 ˜ 5.7 kPa.

  8. The Identification of Nanoscale Structures According to a Parameters of Acoustic Structuroscopy Method

    NASA Astrophysics Data System (ADS)

    Ababkov, N. V.; Smirnov, A. N.; Bykova, N. V.

    2016-04-01

    The fracture surface of a destroyed steam turbine rotor is studied by acoustic structuroscopy method. The structural-phase state of the metal of the destroyed rotor of a steam turbine is studied using the methods of electron microscopy. It was established that in the areas of control, where the values of the acoustic characteristics have significant differences from the rest of the metal, detected nanocrystalline structure. The possibility of determining the structure of the nanoscale metal by acoustic structuroscopy is shown.

  9. Internal strain analysis of ceramics using scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Kent, Renee M.

    1993-01-01

    Quantitative studies of material behavior characteristics are essential for predicting the functionality of a material under its operating conditions. A nonintrusive methodology for measuring the in situ strain of small dimeter (to 11 microns) ceramic fibers under uniaxial tensile loading and the local internal strains of ceramics and ceramic composites under flexural loading is introduced. The strain measurements and experimentally observed mechanical behavior are analyzed in terms of the microstructural development and fracture behavior of each test specimen evaluated. Measurement and analysis of Nicalon silicon carbide (SiC) fiber (15 microns diameter) indicate that the mean elastic modulus of the individual fiber is 185.3 GPa. Deviations observed in the experimentally determined elastic modulus values between specimens were attributed to microstructural variations which occur during processing. Corresponding variations in the fracture surface morphology were also observed. The observed local mechanical behavior of a lithium alumino-silicate (LAS) glass ceramic, a LAS/SiC monofilament composite, and a calcium alumino-silicate (CAS)/SiC fully reinforced composite exhibits nonlinearities and apparent hysteresis due to the subcritical mechanical loading. Local hysteresis in the LAS matrices coincided with the occurrence of multiple fracture initiation sites, localized microcracking, and secondary cracking. The observed microcracking phenomenon was attributed to stress relaxation of residual stresses developed during processing, and local interaction of the crack front with the microstructure. The relaxation strain and stress predicted on apparent mechanical hysteresis effects were defined and correlated with the magnitude of the measured fracture stress for each specimen studied. This quantitative correlation indicated a repeatable measure of the stress at which matrix microcracking occurred for stress relief of each material system. Stress relaxation occurred prior to the onset of steady state cracking conditions. The relaxation stress occurred at 18.5 percent of the fracture stress in LAS and 11.0 percent of the yield stress in CAS/SiC. The relaxation stress ratio was dependent upon the dominant fracture mode of the LAS/SiC specimens. Relaxation stress ratios greater than 0.30 were observed for specimens which fractured due to shear at the fiber matrix interface; specimens which fracture due to tensile cracking had relaxation stress ratios less than 0.30. The stress relaxation ratio appeared to be a specific characteristic of the glass ceramic material. The measured stress relaxation for LAS indicated a measure of the inherent residual stresses in the material due to processing and suggested localized toughening mechanisms for brittle material structures.

  10. Development of a Multichannel Pulser for Acoustic Scanning Microscopy

    NASA Astrophysics Data System (ADS)

    Juhrig, A.; Wolf, M.; Kümmritz, S.; Lenz, M.; Kühnicke, E.

    Modern ultrasound imaging techniques use arrays to manipulate an ultrasound beam and to gather additional information out of the reflected sound field by analysing the received signal of each channel. For further wide-ranging applicability it is required to achieve a higher resolution by increasing the frequency of excitation signals and improvement of the signal to noise ratio. Actually neither electronic hardware nor high-frequency arrays are available that meet these requirements, so that a further development of the control-electronics is indispensable. Therefor the ultrasound pulser presented in [1] was improved with respect to the generation of various excitation signals. A unit consisting out of 16 channels has been developed containing the technology to control these channels as well as to record and to process the received signals. It provides different types of excitation-functions with an excitation-frequency stepwise increasable up to 40 MHz. Additionally the modularised layout allows an extension to control much more elements. All presented improvements are realised in a new ultrasound pulser that offers emission of arbitrary signals on each single channel. Of course the raw data of measurements are accessible and different optional data processing functions are selectable.

  11. Internal strain analysis of ceramics using scanning laser acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Kent, Renee M.

    1993-03-01

    Quantitative studies of material behavior characteristics are essential for predicting the functionality of a material under its operating conditions. A nonintrusive methodology for measuring the in situ strain of small dimeter (to 11 microns) ceramic fibers under uniaxial tensile loading and the local internal strains of ceramics and ceramic composites under flexural loading is introduced. The strain measurements and experimentally observed mechanical behavior are analyzed in terms of the microstructural development and fracture behavior of each test specimen evaluated. Measurement and analysis of Nicalon silicon carbide (SiC) fiber (15 microns diameter) indicate that the mean elastic modulus of the individual fiber is 185.3 GPa. Deviations observed in the experimentally determined elastic modulus values between specimens were attributed to microstructural variations which occur during processing. Corresponding variations in the fracture surface morphology were also observed. The observed local mechanical behavior of a lithium alumino-silicate (LAS) glass ceramic, a LAS/SiC monofilament composite, and a calcium alumino-silicate (CAS)/SiC fully reinforced composite exhibits nonlinearities and apparent hysteresis due to the subcritical mechanical loading. Local hysteresis in the LAS matrices coincided with the occurrence of multiple fracture initiation sites, localized microcracking, and secondary cracking. The observed microcracking phenomenon was attributed to stress relaxation of residual stresses developed during processing, and local interaction of the crack front with the microstructure. The relaxation strain and stress predicted on apparent mechanical hysteresis effects were defined and correlated with the magnitude of the measured fracture stress for each specimen studied. This quantitative correlation indicated a repeatable measure of the stress at which matrix microcracking occurred for stress relief of each material system. Stress relaxation occurred prior to the onset of steady state cracking conditions. The relaxation stress occurred at 18.5 percent of the fracture stress in LAS and 11.0 percent of the yield stress in CAS/SiC. The relaxation stress ratio was dependent upon the dominant fracture mode of the LAS/SiC specimens. Relaxation stress ratios greater than 0.30 were observed for specimens which fractured due to shear at the fiber matrix interface; specimens which fracture due to tensile cracking had relaxation stress ratios less than 0.30. The stress relaxation ratio appeared to be a specific characteristic of the glass ceramic material. The measured stress relaxation for LAS indicated a measure of the inherent residual stresses in the material due to processing and suggested localized toughening mechanisms for brittle material structures.

  12. Transient absorption microscopy studies of single metal and semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Johns, Paul; Sajini-Devadas, Mary; Hartland, Gregory V.

    2015-08-01

    Transient absorption microscopy is an experimental technique that allows nanomaterials to be studied with ultrafast time resolution and diffraction limited spatial resolution. This paper describes recent results from using transient absorption microscopy to investigate energy relaxation processes in single metal and semiconductor nanowires. The processes that have been examined include charge carrier trapping in semiconductor nanostructures, the motion of surface plasmon polaritons in metal nanowires, and the damping of the acoustic breathing modes of metal nanowires by high viscosity solvents.

  13. Acoustics Critical Readiness Review

    NASA Technical Reports Server (NTRS)

    Ballard, Kenny

    2010-01-01

    This presentation reviews the status of the acoustic equipment from the medical operations perspective. Included is information about the acoustic dosimeters, sound level meter, and headphones that are planned for use while on orbit. Finally there is information about on-orbit hearing assessments.

  14. The challenge of acoustics

    NASA Astrophysics Data System (ADS)

    Lord, P.

    1981-01-01

    The various applications of acoustics, including sonar, ultrasonic examination of unborn foetuses and architectural applications, are briefly reviewed. Problems in traffic and industrial noise, auditorium design and explosive noise are considered in more detail. The educational aspects of acoustical science and technology are briefly considered.

  15. Highly directional acoustic receivers.

    PubMed

    Cray, Benjamin A; Evora, Victor M; Nuttall, Albert H

    2003-03-01

    The theoretical directivity of a single combined acoustic receiver, a device that can measure many quantities of an acoustic field at a collocated point, is presented here. The formulation is developed using a Taylor series expansion of acoustic pressure about the origin of a Cartesian coordinate system. For example, the quantities measured by a second-order combined receiver, denoted a dyadic sensor, are acoustic pressure, the three orthogonal components of acoustic particle velocity, and the nine spatial gradients of the velocity vector. The power series expansion, which can be of any order, is cast into an expression that defines the directivity of a single receiving element. It is shown that a single highly directional dyadic sensor can have a directivity index of up to 9.5 dB. However, there is a price to pay with highly directive sensors; these sensors can be significantly more sensitive to nonacoustic noise sources. PMID:12656387

  16. Ocean acoustic hurricane classification.

    PubMed

    Wilson, Joshua D; Makris, Nicholas C

    2006-01-01

    Theoretical and empirical evidence are combined to show that underwater acoustic sensing techniques may be valuable for measuring the wind speed and determining the destructive power of a hurricane. This is done by first developing a model for the acoustic intensity and mutual intensity in an ocean waveguide due to a hurricane and then determining the relationship between local wind speed and underwater acoustic intensity. From this it is shown that it should be feasible to accurately measure the local wind speed and classify the destructive power of a hurricane if its eye wall passes directly over a single underwater acoustic sensor. The potential advantages and disadvantages of the proposed acoustic method are weighed against those of currently employed techniques. PMID:16454274

  17. Acoustic Remote Sensing

    NASA Astrophysics Data System (ADS)

    Dowling, David R.; Sabra, Karim G.

    2015-01-01

    Acoustic waves carry information about their source and collect information about their environment as they propagate. This article reviews how these information-carrying and -collecting features of acoustic waves that travel through fluids can be exploited for remote sensing. In nearly all cases, modern acoustic remote sensing involves array-recorded sounds and array signal processing to recover multidimensional results. The application realm for acoustic remote sensing spans an impressive range of signal frequencies (10-2 to 107 Hz) and distances (10-2 to 107 m) and involves biomedical ultrasound imaging, nondestructive evaluation, oil and gas exploration, military systems, and Nuclear Test Ban Treaty monitoring. In the past two decades, approaches have been developed to robustly localize remote sources; remove noise and multipath distortion from recorded signals; and determine the acoustic characteristics of the environment through which the sound waves have traveled, even when the recorded sounds originate from uncooperative sources or are merely ambient noise.

  18. Acoustic integrated extinction

    PubMed Central

    Norris, Andrew N.

    2015-01-01

    The integrated extinction (IE) is defined as the integral of the scattering cross section as a function of wavelength. Sohl et al. (2007 J. Acoust. Soc. Am. 122, 3206–3210. (doi:10.1121/1.2801546)) derived an IE expression for acoustic scattering that is causal, i.e. the scattered wavefront in the forward direction arrives later than the incident plane wave in the background medium. The IE formula was based on electromagnetic results, for which scattering is causal by default. Here, we derive a formula for the acoustic IE that is valid for causal and non-causal scattering. The general result is expressed as an integral of the time-dependent forward scattering function. The IE reduces to a finite integral for scatterers with zero long-wavelength monopole and dipole amplitudes. Implications for acoustic cloaking are discussed and a new metric is proposed for broadband acoustic transparency. PMID:27547100

  19. Virtual acoustics displays

    NASA Technical Reports Server (NTRS)

    Wenzel, Elizabeth M.; Fisher, Scott S.; Stone, Philip K.; Foster, Scott H.

    1991-01-01

    The real time acoustic display capabilities are described which were developed for the Virtual Environment Workstation (VIEW) Project at NASA-Ames. The acoustic display is capable of generating localized acoustic cues in real time over headphones. An auditory symbology, a related collection of representational auditory 'objects' or 'icons', can be designed using ACE (Auditory Cue Editor), which links both discrete and continuously varying acoustic parameters with information or events in the display. During a given display scenario, the symbology can be dynamically coordinated in real time with 3-D visual objects, speech, and gestural displays. The types of displays feasible with the system range from simple warnings and alarms to the acoustic representation of multidimensional data or events.

  20. Cochlear bionic acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    Ma, Fuyin; Wu, Jiu Hui; Huang, Meng; Fu, Gang; Bai, Changan

    2014-11-01

    A design of bionic acoustic metamaterial and acoustic functional devices was proposed by employing the mammalian cochlear as a prototype. First, combined with the experimental data in previous literatures, it is pointed out that the cochlear hair cells and stereocilia cluster are a kind of natural biological acoustic metamaterials with the negative stiffness characteristics. Then, to design the acoustic functional devices conveniently in engineering application, a simplified parametric helical structure was proposed to replace actual irregular cochlea for bionic design, and based on the computational results of such a bionic parametric helical structure, it is suggested that the overall cochlear is a local resonant system with the negative dynamic effective mass characteristics. There are many potential applications in the bandboard energy recovery device, cochlear implant, and acoustic black hole.

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

    SciTech Connect

    Akal, T.; berkson, J.M.

    1986-01-01

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

  2. Acoustic cooling engine

    DOEpatents

    Hofler, Thomas J.; Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1988-01-01

    An acoustic cooling engine with improved thermal performance and reduced internal losses comprises a compressible fluid contained in a resonant pressure vessel. The fluid has a substantial thermal expansion coefficient and is capable of supporting an acoustic standing wave. A thermodynamic element has first and second ends and is located in the resonant pressure vessel in thermal communication with the fluid. The thermal response of the thermodynamic element to the acoustic standing wave pumps heat from the second end to the first end. The thermodynamic element permits substantial flow of the fluid through the thermodynamic element. An acoustic driver cyclically drives the fluid with an acoustic standing wave. The driver is at a location of maximum acoustic impedance in the resonant pressure vessel and proximate the first end of the thermodynamic element. A hot heat exchanger is adjacent to and in thermal communication with the first end of the thermodynamic element. The hot heat exchanger conducts heat from the first end to portions of the resonant pressure vessel proximate the hot heat exchanger. The hot heat exchanger permits substantial flow of the fluid through the hot heat exchanger. The resonant pressure vessel can include a housing less than one quarter wavelength in length coupled to a reservoir. The housing can include a reduced diameter portion communicating with the reservoir. The frequency of the acoustic driver can be continuously controlled so as to maintain resonance.

  3. Acoustic mapping velocimetry

    NASA Astrophysics Data System (ADS)

    Muste, M.; Baranya, S.; Tsubaki, R.; Kim, D.; Ho, H.; Tsai, H.; Law, D.

    2016-05-01

    Knowledge of sediment dynamics in rivers is of great importance for various practical purposes. Despite its high relevance in riverine environment processes, the monitoring of sediment rates remains a major and challenging task for both suspended and bed load estimation. While the measurement of suspended load is currently an active area of testing with nonintrusive technologies (optical and acoustic), bed load measurement does not mark a similar progress. This paper describes an innovative combination of measurement techniques and analysis protocols that establishes the proof-of-concept for a promising technique, labeled herein Acoustic Mapping Velocimetry (AMV). The technique estimates bed load rates in rivers developing bed forms using a nonintrusive measurements approach. The raw information for AMV is collected with acoustic multibeam technology that in turn provides maps of the bathymetry over longitudinal swaths. As long as the acoustic maps can be acquired relatively quickly and the repetition rate for the mapping is commensurate with the movement of the bed forms, successive acoustic maps capture the progression of the bed form movement. Two-dimensional velocity maps associated with the bed form migration are obtained by implementing algorithms typically used in particle image velocimetry to acoustic maps converted in gray-level images. Furthermore, use of the obtained acoustic and velocity maps in conjunction with analytical formulations (e.g., Exner equation) enables estimation of multidirectional bed load rates over the whole imaged area. This paper presents a validation study of the AMV technique using a set of laboratory experiments.

  4. Some Problems of modern acoustics

    NASA Technical Reports Server (NTRS)

    Stan, A.

    1974-01-01

    The multidisciplinary and interdisciplinary character of acoustics is considered and its scientific, technological, economical and social implications, as well as the role of acoustics in creating new machines and equipment and improving the quality of products are outlined. Research beyond audible frequencies, as well as to extremely high acoustic intensities, which requires the development of a nonlinear acoustics is elaborated.

  5. Acoustic well cleaner

    DOEpatents

    Maki, Jr., Voldi E.; Sharma, Mukul M.

    1997-01-21

    A method and apparatus are disclosed for cleaning the wellbore and the near wellbore region. A sonde is provided which is adapted to be lowered into a borehole and which includes a plurality of acoustic transducers arranged around the sonde. Electrical power provided by a cable is converted to acoustic energy. The high intensity acoustic energy directed to the borehole wall and into the near wellbore region, redissolves or resuspends the material which is reducing the permeability of the formation and/or restricting flow in the wellbore.

  6. Acoustic rotation control

    NASA Technical Reports Server (NTRS)

    Elleman, D. D.; Croonquist, A. P.; Wang, T. G. (Inventor)

    1983-01-01

    A system is described for acoustically controlled rotation of a levitated object, which avoids deformation of a levitated liquid object. Acoustic waves of the same wavelength are directed along perpendicular directions across the object, and with the relative phases of the acoustic waves repeatedly switched so that one wave alternately leads and lags the other by 90 deg. The amount of torque for rotating the object, and the direction of rotation, are controlled by controlling the proportion of time one wave leads the other and selecting which wave leads the other most of the time.

  7. PRSEUS Acoustic Panel Fabrication

    NASA Technical Reports Server (NTRS)

    Nicolette, Velicki; Yovanof, Nicolette P.; Baraja, Jaime; Mathur, Gopal; Thrash, Patrick; Pickell, Robert

    2011-01-01

    This report describes the development of a novel structural concept, Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS), that addresses the demanding fuselage loading requirements for the Hybrid Wing or Blended Wing Body (BWB) airplane configuration with regards to acoustic response. A PRSEUS panel was designed and fabricated and provided to NASA-LaRC for acoustic response testing in the Structural Acoustics Loads and Transmission (SALT) facility). Preliminary assessments of the sound transmission characteristics of a PRSEUS panel subjected to a representative Hybrid Wing Body (HWB) operating environment were completed for the NASA Environmentally Responsible Aviation (ERA) Program.

  8. Acoustical heat pumping engine

    DOEpatents

    Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1983-08-16

    The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium.

  9. Acoustical heat pumping engine

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1983-08-16

    The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium. 2 figs.

  10. Acoustic Neuroma Association

    MedlinePlus

    ... Platinum Sponsors More from this sponsor... Platinum Sponsor Gold Sponsor University of Colorado Acoustic Neuroma Program Rocky Mountain Gamma Knife Center Gold Sponsor NYU Langone Medical Center Departments of Neurosurgery ...

  11. Compact acoustic refrigerator

    DOEpatents

    Bennett, Gloria A.

    1992-01-01

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

  12. Acoustic imaging system

    DOEpatents

    Smith, Richard W.

    1979-01-01

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

  13. Acoustics lecturing in Mexico

    NASA Astrophysics Data System (ADS)

    Beristain, Sergio

    2002-11-01

    Some thirty years ago acoustics lecturing started in Mexico at the National Polytechnic Institute in Mexico City, as part of the Bachelor of Science degree in Communications and Electronics Engineering curricula, including the widest program on this field in the whole country. This program has been producing acoustics specialists ever since. Nowadays many universities and superior education institutions around the country are teaching students at the B.Sc. level and postgraduate level many topics related to acoustics, such as Architectural Acoustics, Seismology, Mechanical Vibrations, Noise Control, Audio, Audiology, Music, etc. Also many institutions have started research programs in related fields, with participation of medical doctors, psychologists, musicians, engineers, etc. Details will be given on particular topics and development.

  14. Compact acoustic refrigerator

    SciTech Connect

    Bennett, G.A.

    1991-12-31

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

  15. Compact acoustic refrigerator

    DOEpatents

    Bennett, G.A.

    1992-11-24

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

  16. Numerical Techniques in Acoustics

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J. (Compiler)

    1985-01-01

    This is the compilation of abstracts of the Numerical Techniques in Acoustics Forum held at the ASME's Winter Annual Meeting. This forum was for informal presentation and information exchange of ongoing acoustic work in finite elements, finite difference, boundary elements and other numerical approaches. As part of this forum, it was intended to allow the participants time to raise questions on unresolved problems and to generate discussions on possible approaches and methods of solution.

  17. Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface.

    PubMed

    Xie, Yangbo; Wang, Wenqi; Chen, Huanyang; Konneker, Adam; Popa, Bogdan-Ioan; Cummer, Steven A

    2014-01-01

    Metasurfaces are a family of novel wavefront-shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality to their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as acoustic imaging, beam steering, ultrasound lens design and acoustic surface wave-based applications. PMID:25418084

  18. Acoustic communication by ants

    NASA Astrophysics Data System (ADS)

    Hickling, Robert

    2002-05-01

    Many ant species communicate acoustically by stridulating, i.e., running a scraper over a washboard-like set of ridges. Ants appear to be insensitive to airborne sound. Consequently, myrmecologists have concluded that the stridulatory signals are transmitted through the substrate. This has tended to diminish the importance of acoustic communication, and it is currently believed that ant communication is based almost exclusively on pheromones, with acoustic communication assigned an almost nonexistent role. However, it can be shown that acoustic communication between ants is effective only if the medium is air and not the substrate. How, then, is it possible for ants to appear deaf to airborne sound and yet communicate through the air? An explanation is provided in a paper [R. Hickling and R. L. Brown, ``Analysis of acoustic communication by ants,'' J. Acoust. Soc. Am. 108, 1920-1929 (2000)]. Ants are small relative to the wavelengths they generate. Hence, they create a near field, which is characterized by a major increase in sound velocity (particle velocity of sound) in the vicinity of the source. Hair sensilla on the ants' antennae respond to sound velocity. Thus, ants are able to detect near-field sound from other ants and to exclude extraneous airborne sound.

  19. Acoustic detection of pneumothorax

    NASA Astrophysics Data System (ADS)

    Mansy, Hansen A.; Royston, Thomas J.; Balk, Robert A.; Sandler, Richard H.

    2003-04-01

    This study aims at investigating the feasibility of using low-frequency (<2000 Hz) acoustic methods for medical diagnosis. Several candidate methods of pneumothorax detection were tested in dogs. In the first approach, broadband acoustic signals were introduced into the trachea during end-expiration and transmitted waves were measured at the chest surface. Pneumothorax was found to consistently decrease pulmonary acoustic transmission in the 200-1200-Hz frequency band, while less change was observed at lower frequencies (p<0.0001). The ratio of acoustic energy between low (<220 Hz) and mid (550-770 Hz) frequency bands was significantly different in the control (healthy) and pneumothorax states (p<0.0001). The second approach measured breath sounds in the absence of an external acoustic input. Pneumothorax was found to be associated with a preferential reduction of sound amplitude in the 200- to 700-Hz range, and a decrease of sound amplitude variation (in the 300 to 600-Hz band) during the respiration cycle (p<0.01 for each). Finally, chest percussion was implemented. Pneumothorax changed the frequency and decay rate of percussive sounds. These results imply that certain medical conditions may be reliably detected using appropriate acoustic measurements and analysis. [Work supported by NIH/NHLBI #R44HL61108.

  20. Ocean acoustic reverberation tomography.

    PubMed

    Dunn, Robert A

    2015-12-01

    Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean bottom seismographs is a common technique for exploring earth structure beneath the oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. For surveys with a small receiver spacing (e.g., <10 km), the acoustic wave field densely samples properties of the water column over the width of the receiver array. A method, referred to as ocean acoustic reverberation tomography, is developed that uses the travel times of direct and reflected waves to image ocean acoustic structure. Reverberation tomography offers an alternative approach for determining the structure of the oceans and advancing the understanding of ocean heat content and mixing processes. The technique has the potential for revealing small-scale ocean thermal structure over the entire vertical height of the water column and along long survey profiles or across three-dimensional volumes of the ocean. For realistic experimental geometries and data noise levels, the method can produce images of ocean sound speed on a smaller scale than traditional acoustic tomography. PMID:26723303

  1. Functional photoacoustic microscopy of pH

    NASA Astrophysics Data System (ADS)

    Chatni, M. Rameez; Yao, Junjie; Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin I.; Wang, Lihong V.

    2012-02-01

    pH is a tightly regulated indicator of metabolic activity. In mammalian systems, imbalance of pH regulation may result from or result in serious illness. Even though the regulation system of pH is very robust, tissue pH can be altered in many diseases such as cancer, osteoporosis and diabetes mellitus. Traditional high-resolution optical imaging techniques, such as confocal microscopy, routinely image pH in cells and tissues using pH sensitive fluorescent dyes, which change their fluorescence properties with the surrounding pH. Since strong optical scattering in biological tissue blurs images at greater depths, high-resolution pH imaging is limited to penetration depths of 1mm. Here, we report photoacoustic microscopy (PAM) of commercially available pH-sensitive fluorescent dye in tissue phantoms. Using both opticalresolution photoacoustic microscopy (OR-PAM), and acoustic resolution photoacoustic microscopy (AR-PAM), we explored the possibility of recovering the pH values in tissue phantoms. In this paper, we demonstrate that PAM was capable of recovering pH values up to a depth of 2 mm, greater than possible with other forms of optical microscopy.

  2. Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  3. A macroscopic non-destructive testing system based on the cantilever-sample contact resonance.

    PubMed

    Fu, Ji; Lin, Lizhi; Zhou, Xilong; Li, Yingwei; Li, Faxin

    2012-12-01

    Detecting the inside or buried defects in materials and structures is always a challenge in the field of nondestructive testing (NDT). In this paper, enlightened by the operation principle of the contact resonance force microscopy or atomic force acoustic microscopy (AFAM), we proposed a macroscopic NDT system based on contact resonance of the cantilever-sample surface to detect the local stiffness variations in materials or structures. We fabricated a piezoelectric unimorph with the dimension typically of 150 mm × 8 mm × 2 mm to act as a macroscopic cantilever, whose flexural mode vibration was driven by a wideband power amplifier together with a signal generator. The vibration signal of the macroscopic cantilever is detected by a high sensitive strain gauge bonded on the cantilever surface which is much more stable than the laser diode sensor in AFAM, thus making it very suitable for outdoor operations. Scanning is realized by a three-dimensional motorized stage with the Z axis for pressing force setting. The whole system is controlled by a LabVIEW-based homemade software. Like the AFAM, this NDT system can also work in two modes, i.e., the single-frequency mode and the resonance-tracking mode. In the latter mode, the contact stiffness at each pixel of the sample can be obtained by using the measured contact resonance frequency and a beam dynamics model. Testing results of this NDT system on a grid structure with an opaque panel show that in both modes the prefabricated defect beneath the panel can be detected and the grid structures can be clearly "seen," which indicates the validity of this NDT system. The sensitivity of this NDT system was also examined. PMID:23277996

  4. Measuring acoustic habitats

    PubMed Central

    Merchant, Nathan D; Fristrup, Kurt M; Johnson, Mark P; Tyack, Peter L; Witt, Matthew J; Blondel, Philippe; Parks, Susan E

    2015-01-01

    1. Many organisms depend on sound for communication, predator/prey detection and navigation. The acoustic environment can therefore play an important role in ecosystem dynamics and evolution. A growing number of studies are documenting acoustic habitats and their influences on animal development, behaviour, physiology and spatial ecology, which has led to increasing demand for passive acoustic monitoring (PAM) expertise in the life sciences. However, as yet, there has been no synthesis of data processing methods for acoustic habitat monitoring, which presents an unnecessary obstacle to would-be PAM analysts. 2. Here, we review the signal processing techniques needed to produce calibrated measurements of terrestrial and aquatic acoustic habitats. We include a supplemental tutorial and template computer codes in matlab and r, which give detailed guidance on how to produce calibrated spectrograms and statistical analyses of sound levels. Key metrics and terminology for the characterisation of biotic, abiotic and anthropogenic sound are covered, and their application to relevant monitoring scenarios is illustrated through example data sets. To inform study design and hardware selection, we also include an up-to-date overview of terrestrial and aquatic PAM instruments. 3. Monitoring of acoustic habitats at large spatiotemporal scales is becoming possible through recent advances in PAM technology. This will enhance our understanding of the role of sound in the spatial ecology of acoustically sensitive species and inform spatial planning to mitigate the rising influence of anthropogenic noise in these ecosystems. As we demonstrate in this work, progress in these areas will depend upon the application of consistent and appropriate PAM methodologies. PMID:25954500

  5. Acoustic emission monitoring system

    DOEpatents

    Romrell, Delwin M.

    1977-07-05

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

  6. ACOUSTICS IN ARCHITECTURAL DESIGN, AN ANNOTATED BIBLIOGRAPHY ON ARCHITECTURAL ACOUSTICS.

    ERIC Educational Resources Information Center

    DOELLE, LESLIE L.

    THE PURPOSE OF THIS ANNOTATED BIBLIOGRAPHY ON ARCHITECTURAL ACOUSTICS WAS--(1) TO COMPILE A CLASSIFIED BIBLIOGRAPHY, INCLUDING MOST OF THOSE PUBLICATIONS ON ARCHITECTURAL ACOUSTICS, PUBLISHED IN ENGLISH, FRENCH, AND GERMAN WHICH CAN SUPPLY A USEFUL AND UP-TO-DATE SOURCE OF INFORMATION FOR THOSE ENCOUNTERING ANY ARCHITECTURAL-ACOUSTIC DESIGN…

  7. Acoustic energy shaping

    NASA Technical Reports Server (NTRS)

    Wang, T. G.; Elleman, D. D. (Inventor)

    1977-01-01

    A suspended mass is shaped by melting all or a selected portion of the mass and applying acoustic energy in varying amounts to different portions of the mass. In one technique for forming an optical waveguide slug, a mass of oval section is suspended and only a portion along the middle of the cross-section is heated to a largely fluid consistency. Acoustic energy is applied to opposite edges of the oval mass to press the unheated opposite edge portions together so as to form bulges at the middle of the mass. In another technique for forming a ribbon of silicon for constructing solar cells, a cylindrical thread of silicon is drawn from a molten mass of silicon, and acoustic energy is applied to opposite sides of the molten thread to flatten it into a ribbon.

  8. Passive broadband acoustic thermometry

    NASA Astrophysics Data System (ADS)

    Anosov, A. A.; Belyaev, R. V.; Klin'shov, V. V.; Mansfel'd, A. D.; Subochev, P. V.

    2016-04-01

    The 1D internal (core) temperature profiles for the model object (plasticine) and the human hand are reconstructed using the passive acoustothermometric broadband probing data. Thermal acoustic radiation is detected by a broadband (0.8-3.5 MHz) acoustic radiometer. The temperature distribution is reconstructed using a priori information corresponding to the experimental conditions. The temperature distribution for the heated model object is assumed to be monotonic. For the hand, we assume that the temperature distribution satisfies the heat-conduction equation taking into account the blood flow. The average error of reconstruction determined for plasticine from the results of independent temperature measurements is 0.6 K for a measuring time of 25 s. The reconstructed value of the core temperature of the hand (36°C) generally corresponds to physiological data. The obtained results make it possible to use passive broadband acoustic probing for measuring the core temperatures in medical procedures associated with heating of human organism tissues.

  9. Surface Acoustic Wave Microfluidics

    NASA Astrophysics Data System (ADS)

    Yeo, Leslie Y.; Friend, James R.

    2014-01-01

    Fluid manipulations at the microscale and beyond are powerfully enabled through the use of 10-1,000-MHz acoustic waves. A superior alternative in many cases to other microfluidic actuation techniques, such high-frequency acoustics is almost universally produced by surface acoustic wave devices that employ electromechanical transduction in wafer-scale or thin-film piezoelectric media to generate the kinetic energy needed to transport and manipulate fluids placed in adjacent microfluidic structures. These waves are responsible for a diverse range of complex fluid transport phenomena - from interfacial fluid vibration and drop and confined fluid transport to jetting and atomization - underlying a flourishing research literature spanning fundamental fluid physics to chip-scale engineering applications. We highlight some of this literature to provide the reader with a historical basis, routes for more detailed study, and an impression of the field's future directions.

  10. Latticed pentamode acoustic cloak

    PubMed Central

    Chen, Yi; Liu, Xiaoning; Hu, Gengkai

    2015-01-01

    We report in this work a practical design of pentamode acoustic cloak with microstructure. The proposed cloak is assembled by pentamode lattice made of a single-phase solid material. The function of rerouting acoustic wave round an obstacle has been demonstrated numerically. It is also revealed that shear related resonance due to weak shear resistance in practical pentamode lattices punctures broadband feature predicted based on ideal pentamode cloak. As a consequence, the latticed pentamode cloak can only conceal the obstacle in segmented frequency ranges. We have also shown that the shear resonance can be largely reduced by introducing material damping, and an improved broadband performance can be achieved. These works pave the way for experimental demonstration of pentamode acoustic cloak. PMID:26503821

  11. Seamount acoustic scattering

    NASA Astrophysics Data System (ADS)

    Boehlert, George W.

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

  12. A New Wave of Acoustics.

    ERIC Educational Resources Information Center

    Beyer, Robert

    1981-01-01

    Surveys 50 years of acoustical studies by discussing selected topics including the ear, nonlinear representations, underwater sound, acoustical diagnostics, absorption, electrolytes, phonons, magnetic interaction, and superfluidity and the five sounds. (JN)

  13. Surface acoustic wave/silicon monolithic sensor/processor

    NASA Technical Reports Server (NTRS)

    Kowel, S. T.; Kornreich, P. G.; Nouhi, A.; Kilmer, R.; Fathimulla, M. A.; Mehter, E.

    1983-01-01

    A new technique for sputter deposition of piezoelectric zinc oxide (ZnO) is described. An argon-ion milling system was converted to sputter zinc oxide films in an oxygen atmosphere using a pure zinc oxide target. Piezoelectric films were grown on silicon dioxide and silicon dioxide overlayed with gold. The sputtered films were evaluated using surface acoustic wave measurements, X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, and resistivity measurements. The effect of the sputtering conditions on the film quality and the result of post-deposition annealing are discussed. The application of these films to the generation of surface acoustic waves is also discussed.

  14. Densitometry By Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Trinh, Eugene H.

    1989-01-01

    "Static" and "dynamic" methods developed for measuring mass density of acoustically levitated solid particle or liquid drop. "Static" method, unknown density of sample found by comparison with another sample of known density. "Dynamic" method practiced with or without gravitational field. Advantages over conventional density-measuring techniques: sample does not have to make contact with container or other solid surface, size and shape of samples do not affect measurement significantly, sound field does not have to be know in detail, and sample can be smaller than microliter. Detailed knowledge of acoustic field not necessary.

  15. Acoustic tooth cleaner

    NASA Technical Reports Server (NTRS)

    Heyman, J. S. (Inventor)

    1982-01-01

    An acoustic oral hygiene unit is described that uses acoustic energy to oscillate mild abrasive particles in a water suspension which is then directed in a low pressure stream onto the teeth. The oscillating abrasives scrub the teeth clean removing food particles, plaque, calculous, and other foreign material from tooth surfaces, interproximal areas, and tooth-gingiva interface more effectively than any previous technique. The relatively low power output and the basic design makes the invention safe and convenient for everyday use in the home without special training. This invention replaces all former means of home dental prophylaxis, and requires no augmentation to fulfill all requirements for daily oral hygienic care.

  16. Acoustic emission intrusion detector

    DOEpatents

    Carver, Donald W.; Whittaker, Jerry W.

    1980-01-01

    An intrusion detector is provided for detecting a forcible entry into a secured structure while minimizing false alarms. The detector uses a piezoelectric crystal transducer to sense acoustic emissions. The transducer output is amplified by a selectable gain amplifier to control the sensitivity. The rectified output of the amplifier is applied to a Schmitt trigger circuit having a preselected threshold level to provide amplitude discrimination. Timing circuitry is provided which is activated by successive pulses from the Schmitt trigger which lie within a selected time frame for frequency discrimination. Detected signals having proper amplitude and frequency trigger an alarm within the first complete cycle time of a detected acoustical disturbance signal.

  17. Strong acoustic wave action

    NASA Astrophysics Data System (ADS)

    Gokhberg, M. B.

    1983-07-01

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

  18. Acoustic bubble removal method

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Elleman, D. D.; Wang, T. G. (Inventor)

    1983-01-01

    A method is described for removing bubbles from a liquid bath such as a bath of molten glass to be used for optical elements. Larger bubbles are first removed by applying acoustic energy resonant to a bath dimension to drive the larger bubbles toward a pressure well where the bubbles can coalesce and then be more easily removed. Thereafter, submillimeter bubbles are removed by applying acoustic energy of frequencies resonant to the small bubbles to oscillate them and thereby stir liquid immediately about the bubbles to facilitate their breakup and absorption into the liquid.

  19. Acoustic and electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Jones, Douglas Samuel

    Theoretical models of EM and acoustic wave propagation are presented in an introductory text intended for intermediate-level science and engineering students. Chapters are devoted to the mathematical representation of acoustic and EM fields, the special theory of relativity, radiation, resonators, waveguide theory, refraction, surface waves, scattering by smooth objects, diffraction by edges, and transient waves. The mathematical tools required for the analysis (Bessel, Legendre, Mathieu, parabolic-cylinder, and spheroidal functions; tensor calculus; and the asymptotic evaluation of integrals) are covered in appendices.

  20. Structural Acoustics and Vibrations

    NASA Astrophysics Data System (ADS)

    Chaigne, Antoine

    This chapter is devoted to vibrations of structures and to their coupling with the acoustic field. Depending on the context, the radiated sound can be judged as desirable, as is mostly the case for musical instruments, or undesirable, like noise generated by machinery. In architectural acoustics, one main goal is to limit the transmission of sound through walls. In the automobile industry, the engineers have to control the noise generated inside and outside the passenger compartment. This can be achieved by means of passive or active damping. In general, there is a strong need for quieter products and better sound quality generated by the structures in our daily environment.

  1. Electromechanical acoustic liner

    NASA Technical Reports Server (NTRS)

    Sheplak, Mark (Inventor); Cattafesta, III, Louis N. (Inventor); Nishida, Toshikazu (Inventor); Horowitz, Stephen Brian (Inventor)

    2007-01-01

    A multi-resonator-based system responsive to acoustic waves includes at least two resonators, each including a bottom plate, side walls secured to the bottom plate, and a top plate disposed on top of the side walls. The top plate includes an orifice so that a portion of an incident acoustical wave compresses gas in the resonators. The bottom plate or the side walls include at least one compliant portion. A reciprocal electromechanical transducer coupled to the compliant portion of each of the resonators forms a first and second transducer/compliant composite. An electrical network is disposed between the reciprocal electromechanical transducer of the first and second resonator.

  2. Acoustic diagnosis for nondestructive evaluation of ceramic coatings on steel substrates

    SciTech Connect

    Aizawa, Tatsuhiko; Kihara, Junji; Ito, Manabu

    1995-11-01

    New methodology is proposed and developed to make quantitative nondestructive evaluation of TiN coated SKH steel substrates. Since the measured acoustic structure is in precise correspondence with the multi-layered elastic media, change of elastic properties by degradation and damage can be easily distinguished by the acoustic spectro microscopy. In particular, rather complex acoustic structure can be measured by the present method for ceramic coated steel substrate system, but it is completely described by the two-layer model in two dimensional elasticity. Typical example is the cut-off phenomenon where the dispersion curve for the leaky surface wave velocity is forced to be terminated by alternative activation of shear wave instead of it. The quantitative nondestructive diagnosis was developed on the basis of this predictable acoustic structure. Furthermore, the effect of coating conditions on the acoustic structure is also discussed to make residual stress distribution analysis in coating by the acoustic spectro microscopy with reference to the X-ray stress analysis. Some comments are made on further advancement of the present acoustic spectro microscopy adaptive to precise characterization of ceramic coatings and practical sensing system working in practice.

  3. Acoustic loading in straight pipes

    NASA Technical Reports Server (NTRS)

    El-Raheb, M.

    1980-01-01

    Based on linear one-dimensional acoustics, a geometrically perfect elastic waveguide would respond to an oscillatory internal pressure only in the presence of path deflectors (elbows and branches). In practice, a significant elasto-acoustic interaction results even in straight conduits as a result of manufacturing tolerances. A theoretical model of the linear acoustic loading in straight pipes is developed that considers the acoustic wave distortion due to perimeter, axial, and wall thickness nonuniformities.

  4. Spacecraft Internal Acoustic Environment Modeling

    NASA Technical Reports Server (NTRS)

    Allen, Christopher; Chu, S. Reynold

    2008-01-01

    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 to ensure compliance with acoustic requirements and thus provide a safe and habitable acoustic environment for the crews, and to validate developed models via building physical mockups and conducting acoustic measurements.

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

    NASA Technical Reports Server (NTRS)

    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

  6. Microscopy using source and detector arrays

    NASA Astrophysics Data System (ADS)

    Sheppard, Colin J. R.; Castello, Marco; Vicidomini, Giuseppe; Duocastella, Martí; Diaspro, Alberto

    2016-03-01

    There are basically two types of microscope, which we call conventional and scanning. The former type is a full-field imaging system. In the latter type, the object is illuminated with a probe beam, and a signal detected. We can generalize the probe to a patterned illumination. Similarly we can generalize the detection to a patterned detection. Combining these we get a range of different modalities: confocal microscopy, structured illumination (with full-field imaging), spinning disk (with multiple illumination points), and so on. The combination allows the spatial frequency bandwidth of the system to be doubled. In general we can record a four dimensional (4D) image of a 2D object (or a 6D image from a 3D object, using an acoustic tuneable lens). The optimum way to directly reconstruct the resulting image is by image scanning microscopy (ISM). But the 4D image is highly redundant, so deconvolution-based approaches are also relevant. ISM can be performed in fluorescence, bright field or interference microscopy. Several different implementations have been described, with associated advantages and disadvantages. In two-photon microscopy, the illumination and detection point spread functions are very different. This is also the case when using pupil filters or when there is a large Stokes shift.

  7. Variable-Position Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Stoneburner, J. D.; Jacobi, N.; Wang, T. G.

    1983-01-01

    Method of acoustic levitation supports objects at positions other than acoustic nodes. Acoustic force is varied so it balances gravitational (or other) force, thereby maintaining object at any position within equilibrium range. Levitation method applicable to containerless processing. Such objects as table-tennis balls, hollow plastic spheres, and balsa-wood spheres levitated in laboratory by new method.

  8. Acoustical Environment of School Buildings.

    ERIC Educational Resources Information Center

    Fitzroy, Dariel; Reid, John L.

    A field study was made of the acoustical environment of schools designed for increased flexibility to meet the spatial requirements of new teaching methods. The object of the study was to define all the criteria for the acoustical design of this type of classroom including the determination of--(1) minimum acoustical separation required for…

  9. ACOUSTICAL ENVIRONMENT OF SCHOOL BUILDINGS.

    ERIC Educational Resources Information Center

    FITZROY, DARIEL; REID, JOHN L.

    A FIELD STUDY WAS MADE OF THE ACOUSTICAL ENVIRONMENT OF SCHOOLS DESIGNED FOR INCREASED FLEXIBILITY TO MEET THE SPATIAL REQUIREMENTS OF NEW TEACHING METHODS. THE OBJECT OF THE STUDY WAS TO DEFINE ALL THE CRITERIA FOR THE ACOUSTICAL DESIGN OF THIS TYPE OF CLASSROOM INCLUDING THE DETERMINATION OF--(1) MINIMUM ACOUSTICAL SEPARATION REQUIRED FOR…

  10. Post Treatment of Acoustic Neuroma

    MedlinePlus

    Home What is an AN What is an Acoustic Neuroma? Identifying an AN Symptoms Acoustic Neuroma Keywords Educational Video Pre-Treatment Treatment Options Summary Treatment Options Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions ...

  11. Comparison between optical-resolution photoacoustic microscopy and confocal laser scanning microscopy for turbid sample imaging

    NASA Astrophysics Data System (ADS)

    U-Thainual, Paweena; Kim, Do-Hyun

    2015-12-01

    Optical-resolution photoacoustic microscopy (ORPAM) in theory provides lateral resolution equivalent to the optical diffraction limit. Scattering media, such as biological turbid media, attenuates the optical signal and also alters the diffraction-limited spot size of the focused beam. The ORPAM signal is generated only from a small voxel in scattering media with dimensions equivalent to the laser spot size after passing through scattering layers and is detected by an acoustic transducer, which is not affected by optical scattering. Thus, both ORPAM and confocal laser scanning microscopy (CLSM) reject scattered light. A multimodal optical microscopy platform that includes ORPAM and CLSM was constructed, and the lateral resolution of both modes was measured using patterned thin metal film with and without a scattering barrier. The effect of scattering media on the lateral resolution was studied using different scattering coefficients and was compared to computational results based on Monte Carlo simulations. It was found that degradation of lateral resolution due to optical scattering was not significant for either ORPAM or CLSM. The depth discrimination capability of ORPAM and CLSM was measured using microfiber embedded in a light scattering phantom material. ORPAM images demonstrated higher contrast compared to CLSM images partly due to reduced acoustic signal scattering.

  12. Comparison between optical-resolution photoacoustic microscopy and confocal laser scanning microscopy for turbid sample imaging.

    PubMed

    U-Thainual, Paweena; Kim, Do-Hyun

    2015-12-01

    Optical-resolution photoacoustic microscopy (ORPAM) in theory provides lateral resolution equivalent to the optical diffraction limit. Scattering media, such as biological turbid media, attenuates the optical signal and also alters the diffraction-limited spot size of the focused beam. The ORPAM signal is generated only from a small voxel in scattering media with dimensions equivalent to the laser spot size after passing through scattering layers and is detected by an acoustic transducer, which is not affected by optical scattering. Thus, both ORPAM and confocal laser scanning microscopy (CLSM) reject scattered light. A multimodal optical microscopy platform that includes ORPAM and CLSM was constructed, and the lateral resolution of both modes was measured using patterned thin metal film with and without a scattering barrier. The effect of scattering media on the lateral resolution was studied using different scattering coefficients and was compared to computational results based on Monte Carlo simulations. It was found that degradation of lateral resolution due to optical scattering was not significant for either ORPAM or CLSM. The depth discrimination capability of ORPAM and CLSM was measured using microfiber embedded in a light scattering phantom material. ORPAM images demonstrated higher contrast compared to CLSM images partly due to reduced acoustic signal scattering. PMID:26256640

  13. Fundamentals of Acoustics. Psychoacoustics and Hearing. Acoustical Measurements

    NASA Technical Reports Server (NTRS)

    Begault, Durand R.; Ahumada, Al (Technical Monitor)

    1997-01-01

    These are 3 chapters that will appear in a book titled "Building Acoustical Design", edited by Charles Salter. They are designed to introduce the reader to fundamental concepts of acoustics, particularly as they relate to the built environment. "Fundamentals of Acoustics" reviews basic concepts of sound waveform frequency, pressure, and phase. "Psychoacoustics and Hearing" discusses the human interpretation sound pressure as loudness, particularly as a function of frequency. "Acoustic Measurements" gives a simple overview of the time and frequency weightings for sound pressure measurements that are used in acoustical work.

  14. Acoustic subwavelength imaging of subsurface objects with acoustic resonant metalens

    SciTech Connect

    Cheng, Ying; Liu, XiaoJun; Zhou, Chen; Wei, Qi; Wu, DaJian

    2013-11-25

    Early research into acoustic metamaterials has shown the possibility of achieving subwavelength near-field acoustic imaging. However, a major restriction of acoustic metamaterials is that the imaging objects must be placed in close vicinity of the devices. Here, we present an approach for acoustic imaging of subsurface objects far below the diffraction limit. An acoustic metalens made of holey-structured metamaterials is used to magnify evanescent waves, which can rebuild an image at the central plane. Without changing the physical structure of the metalens, our proposed approach can image objects located at certain distances from the input surface, which provides subsurface signatures of the objects with subwavelength spatial resolution.

  15. Microfiber interferometric acoustic transducers.

    PubMed

    Wang, Xiuxin; Jin, Long; Li, Jie; Ran, Yang; Guan, Bai-Ou

    2014-04-01

    Acoustic and ultrasonic transducers are key components in biomedical information technology, which has been applied in medical diagnosis, photoacoustic endoscopy and photoacoustic imaging. In this paper, an acoustic transducer based on Fabry-Perot interferometer (FPI) fabricated in a microscaled optical fiber is demonstrated. The transducer is fabricated by forming two wavelength-matched Bragg gratings into the microfiber by means of side illumination with a 193nm excimer laser. When placing the transducer in water, the applied acoustic signal periodically changes the refractive index (RI) of the surrounding liquid and modulates the transmission of the FPI based on the evanescent-field interaction between the liquid and the transmitting light. As a result, the acoustic signal can be constructed with a tunable laser whose output wavelength is located at the slope of the inteferometric fringes. The transducer presents a sensitivity of 10 times higher than the counterparts fabricated in conventional singlemode fibers and has great potential to achieve higher resolution for photoacoustic imaging due to its reduced diameter. PMID:24718189

  16. Intelligent Engine Systems: Acoustics

    NASA Technical Reports Server (NTRS)

    Wojno, John; Martens, Steve; Simpson, Benjamin

    2008-01-01

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

  17. Acoustics in Schools.

    ERIC Educational Resources Information Center

    Singer, Miriam J.

    This paper explores the issues associated with poor acoustics within schools. Additionally, it suggests remedies for existing buildings and those under renovation, as well as concerns for new construction. The paper discusses the effects of unwanted noise on students in terms of physiological, motivational, and cognitive influences. Issues are…

  18. Teaching acoustics online

    NASA Astrophysics Data System (ADS)

    Morrison, Andrew; Rossing, Thomas D.

    2003-10-01

    We teach an introductory course in musical acoustics using a Blackboard. Students in this course can access audio and video materials as well as printed materials on our course website. All homework is submitted online, as are tests and examinations. The students also have the opportunity to use synchronous and asynchronous chat rooms to discuss the course with each other or with the instructors.

  19. Micro acoustic spectrum analyzer

    DOEpatents

    Schubert, W. Kent; Butler, Michael A.; Adkins, Douglas R.; Anderson, Larry F.

    2004-11-23

    A micro acoustic spectrum analyzer for determining the frequency components of a fluctuating sound signal comprises a microphone to pick up the fluctuating sound signal and produce an alternating current electrical signal; at least one microfabricated resonator, each resonator having a different resonant frequency, that vibrate in response to the alternating current electrical signal; and at least one detector to detect the vibration of the microfabricated resonators. The micro acoustic spectrum analyzer can further comprise a mixer to mix a reference signal with the alternating current electrical signal from the microphone to shift the frequency spectrum to a frequency range that is a better matched to the resonant frequencies of the microfabricated resonators. The micro acoustic spectrum analyzer can be designed specifically for portability, size, cost, accuracy, speed, power requirements, and use in a harsh environment. The micro acoustic spectrum analyzer is particularly suited for applications where size, accessibility, and power requirements are limited, such as the monitoring of industrial equipment and processes, detection of security intrusions, or evaluation of military threats.

  20. COMBUSTION ACOUSTICS DIAGNOSTICS

    EPA Science Inventory

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

  1. Advances in Urine Microscopy.

    PubMed

    Becker, Gavin J; Garigali, Giuseppe; Fogazzi, Giovanni B

    2016-06-01

    Urine microscopy is an important tool for the diagnosis and management of several conditions affecting the kidneys and urinary tract. In this review, we describe the automated instruments, based either on flow cytometry or digitized microscopy, that are currently in use in large clinical laboratories. These tools allow the examination of large numbers of samples in short periods. We also discuss manual urinary microscopy commonly performed by nephrologists, which we encourage. After discussing the advantages of phase contrast microscopy over bright field microscopy, we describe the advancements of urine microscopy in various clinical conditions. These include persistent isolated microscopic hematuria (which can be classified as glomerular or nonglomerular on the basis of urinary erythrocyte morphology), drug- and toxin-related cystalluria (which can be a clue for the diagnosis of acute kidney injury associated with intrarenal crystal precipitation), and some inherited conditions (eg, adenine phosphoribosyltransferase deficiency, which is associated with 2,8-dihydroxyadenine crystalluria, and Fabry disease, which is characterized by unique urinary lamellated fatty particles). Finally, we describe the utility of identifying "decoy cells" and atypical malignant cells, which can be easily done with phase contrast microscopy in unfixed samples. PMID:26806004

  2. Superresolution microscopy for microbiology

    PubMed Central

    Coltharp, Carla; Xiao, Jie

    2014-01-01

    Summary This review provides a practical introduction to superresolution microscopy from the perspective of microbiological research. Because of the small sizes of bacterial cells, superresolution methods are particularly powerful and suitable for revealing details of cellular structures that are not resolvable under conventional fluorescence light microscopy. Here we describe the methodological concepts behind three major categories of super-resolution light microscopy: photoactivated localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM), structured illumination microscopy (SIM) and stimulated emission-depletion (STED) microscopy. We then present recent applications of each of these techniques to microbial systems, which have revealed novel conformations of cellular structures and described new properties of in vivo protein function and interactions. Finally, we discuss the unique issues related to implementing each of these superresolution techniques with bacterial specimens and suggest avenues for future development. The goal of this review is to provide the necessary technical background for interested microbiologists to choose the appropriate super-resolution method for their biological systems, and to introduce the practical considerations required for designing and analysing superresolution imaging experiments. PMID:22947061

  3. Acoustics- Version 1.0

    SciTech Connect

    2012-09-13

    This package contains modules that model acoustic sensors and acoustic sources (hearable) in Umbra. It is typically used to represent hearing in characters within Umbra. Typically, the acoustic sensors detect acoustic sources at a given point; however, it also contains the capability to detect bullet cracks by detecting the sound along the bullet path that is closest to the sensor. A memory module, acoustic memory, represents remembered sounds within a given character. Over time, the sounds are removed, as a character forgets what it has heard.

  4. Acoustics- Version 1.0

    2012-09-13

    This package contains modules that model acoustic sensors and acoustic sources (hearable) in Umbra. It is typically used to represent hearing in characters within Umbra. Typically, the acoustic sensors detect acoustic sources at a given point; however, it also contains the capability to detect bullet cracks by detecting the sound along the bullet path that is closest to the sensor. A memory module, acoustic memory, represents remembered sounds within a given character. Over time, themore » sounds are removed, as a character forgets what it has heard.« less

  5. On photo-expansion and microlens formation in (GeS{sub 2}){sub 0.74}(Sb{sub 2}S{sub 3}){sub 0.26} chalcogenide glass

    SciTech Connect

    Knotek, P.; Tichy, L.

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Photo-expansion induced by sub-band-gap photons in GeSbS glass. ► One-step microlens formation. ► The topography of the microlenses detected by AFM and DHM. ► The good mechanical characteristics of the microlenses were obtained. ► Local light-induced overheating of the glass. -- Abstract: Photo-expansion of the bulk of (GeS{sub 2}){sub 0.74}(Sb{sub 2}S{sub 3}){sub 0.26} glass induced by sub-gap photons is studied employing specifically atomic force microscopy (AFM) namely an atomic force acoustic microscopy (AFAM) and a force spectroscopy and digital holographic microscopy. The results are discussed with respect to the possible role of light induced overheating in the process of photo-expansion.

  6. An Estimate of Biofilm Properties using an Acoustic Microscope

    SciTech Connect

    Good, Morris S.; Wend, Christopher F.; Bond, Leonard J.; Mclean, Jeffrey S.; Panetta, Paul D.; Ahmed, Salahuddin; Crawford, Susan L.; Daly, Don S.

    2006-09-01

    Noninvasive measurements over a biofilm, a three-dimensional community of microorganisms immobilized at a substratum, were made using an acoustic microscope operating at frequencies up to 70 MHz. Spatial variation of surface heterogeneity, thickness, interior structure, and biomass of a living biofilm was estimated over a 2.5-mm by 2.5-mm region. Ultrasound based estimates of thickness were corroborated using optical microscopy and the nominal biofilm thickness was 100 microns. Experimental data showed that the acoustic microscope combined with signal processing was capable of imaging and making quantitative estimates of the spatial distribution of biomass within the biofilm. The revealed surface topology and interior structure of the biofilm provide data for use in advanced biofilm mass transport models. The experimental acoustic and optical systems, methods to estimate of biofilm properties and potential applications for the resulting data are discussed.

  7. Clinical specular microscopy

    SciTech Connect

    Hirst, L.W.; Laing, R.A.

    1987-01-01

    This book provides the general ophthalmologist with a guide to the clinical applications of specular microscopy. Important material is included on laser injury, cataract surgery, corneal transplants, glaucoma, uveitis, and trauma.

  8. Ultrafast scanning probe microscopy

    SciTech Connect

    Botkin, D.; Weiss, S.; Ogletree, D.F.; Salmeron, M.; Chemla, D.S.

    1994-01-01

    The authors have developed a general technique which combines the temporal resolution of ultrafast laser spectroscopy with the spatial resolution of scanned probe microscopy (SPM). Using this technique with scanning tunneling microscopy (STM), they have obtained simultaneous 2 ps time resolution and 50 {angstrom} spatial resolution. This improves the time resolution currently attainable with STM by nine orders of magnitude. The potential of this powerful technique for studying ultrafast dynamical phenomena on surfaces with atomic resolution is discussed.

  9. Acoustic Suppression Systems and Related Methods

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  10. Transient response of tapping scanning force microscopy in liquids

    SciTech Connect

    Chen, G.Y.; Warmack, R.J. |; Oden, P.I.; Thundat, T.

    1996-03-01

    Tapping-mode scanning force microscopy in liquids is usually accomplished by acoustic excitation of the cantilever because of the strong viscous damping. Contact of the tip with the sample surface results in a damping of the cantilever amplitude with an anharmonic response. This interaction is modeled as a viscous-damped, one-dimensional harmonic oscillator periodically perturbed by an exponential surface potential. Experimental results verify the validity of the model. {copyright} {ital 1996 American Vacuum Society}

  11. Education in acoustics in Argentina

    NASA Astrophysics Data System (ADS)

    Miyara, Federico

    2002-11-01

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

  12. Acoustic energy harvesting based on a planar acoustic metamaterial

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  13. Acoustics Discipline Overview

    NASA Technical Reports Server (NTRS)

    Envia, Edmane; Thomas, Russell

    2007-01-01

    As part of the Fundamental Aeronautics Program Annual Review, a summary of the progress made in 2007 in acoustics research under the Subsonic Fixed Wing project is given. The presentation describes highlights from in-house and external activities including partnerships and NRA-funded research with industry and academia. Brief progress reports from all acoustics Phase 1 NRAs are also included as are outlines of the planned activities for 2008 and all Phase 2 NRAs. N+1 and N+2 technology paths outlined for Subsonic Fixed Wing noise targets. NRA Round 1 progressing with focus on prediction method advancement. NRA Round 2 initiating work focused on N+2 technology, prediction methods, and validation. Excellent partnerships in progress supporting N+1 technology targets and providing key data sets.

  14. Radiosurgery of acoustic neurinomas

    SciTech Connect

    Flickinger, J.C.; Lunsford, L.D.; Coffey, R.J.; Linskey, M.E.; Bissonette, D.J.; Maitz, A.H.; Kondziolka, D. )

    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.

  15. Acoustic methodology review

    NASA Technical Reports Server (NTRS)

    Schlegel, R. G.

    1982-01-01

    It is important for industry and NASA to assess the status of acoustic design technology for predicting and controlling helicopter external noise in order for a meaningful research program to be formulated which will address this problem. The prediction methodologies available to the designer and the acoustic engineer are three-fold. First is what has been described as a first principle analysis. This analysis approach attempts to remove any empiricism from the analysis process and deals with a theoretical mechanism approach to predicting the noise. The second approach attempts to combine first principle methodology (when available) with empirical data to formulate source predictors which can be combined to predict vehicle levels. The third is an empirical analysis, which attempts to generalize measured trends into a vehicle noise prediction method. This paper will briefly address each.

  16. Acoustic tractor beam.

    PubMed

    Démoré, Christine E M; Dahl, Patrick M; Yang, Zhengyi; Glynne-Jones, Peter; Melzer, Andreas; Cochran, Sandy; MacDonald, Michael P; Spalding, Gabriel C

    2014-05-01

    Negative radiation forces act opposite to the direction of propagation, or net momentum, of a beam but have previously been challenging to definitively demonstrate. We report an experimental acoustic tractor beam generated by an ultrasonic array operating on macroscopic targets (>1 cm) to demonstrate the negative radiation forces and to map out regimes over which they dominate, which we compare to simulations. The result and the geometrically simple configuration show that the effect is due to nonconservative forces, produced by redirection of a momentum flux from the angled sides of a target and not by conservative forces from a potential energy gradient. Use of a simple acoustic setup provides an easily understood illustration of the negative radiation pressure concept for tractor beams and demonstrates continuous attraction towards the source, against a net momentum flux in the system. PMID:24836252

  17. Acoustic Tractor Beam

    NASA Astrophysics Data System (ADS)

    Démoré, Christine E. M.; Dahl, Patrick M.; Yang, Zhengyi; Glynne-Jones, Peter; Melzer, Andreas; Cochran, Sandy; MacDonald, Michael P.; Spalding, Gabriel C.

    2014-05-01

    Negative radiation forces act opposite to the direction of propagation, or net momentum, of a beam but have previously been challenging to definitively demonstrate. We report an experimental acoustic tractor beam generated by an ultrasonic array operating on macroscopic targets (>1 cm) to demonstrate the negative radiation forces and to map out regimes over which they dominate, which we compare to simulations. The result and the geometrically simple configuration show that the effect is due to nonconservative forces, produced by redirection of a momentum flux from the angled sides of a target and not by conservative forces from a potential energy gradient. Use of a simple acoustic setup provides an easily understood illustration of the negative radiation pressure concept for tractor beams and demonstrates continuous attraction towards the source, against a net momentum flux in the system.

  18. Alaskan river environmental acoustics

    NASA Astrophysics Data System (ADS)

    Dahl, Peter H.; Pfisterer, Carl; Geiger, Harold J.

    2005-04-01

    Sonars are used by the Alaska Department of Fish and Game (ADF&G) to obtain daily and hourly estimates of at least four species of migratory salmon during their seasonal migration which lasts from June to beginning of September. Suspended sediments associated with a river's sediment load is an important issue for ADF&G's sonar operations. Acoustically, the suspended sediments are a source of both volume reverberation and excess attenuation beyond that expected in fresh water. Each can impact daily protocols for fish enumeration via sonar. In this talk, results from an environmental acoustic study conducted in the Kenai River (June 1999) using 420 kHz and 200 kHz side looking sonars, and in the Yukon River (July 2001) using a 120 kHz side looking sonar, are discussed. Estimates of the volume scattering coefficient and attenuation are related to total suspended sediments. The relative impact of bubble scattering and sediment scattering is also discussed.

  19. Structural Acoustics and Vibrations

    NASA Astrophysics Data System (ADS)

    Chaigne, Antoine

    This structural chapter is devoted to vibrations of structures and to their coupling with the acoustic field. Depending on the context, the radiated sound can be judged as desirable, as is mostly the case for musical instruments, or undesirable, like noise generated by machinery. In architectural acoustics, one main goal is to limit the transmission of sound through walls. In the automobile industry, the engineers have to control the noise generated inside and outside the passenger compartment. This can be achieved by means of passive or active damping. In general, there is a strong need for quieter products and better sound quality generated by the structures in our daily environment.

  20. A Martian acoustic anemometer.

    PubMed

    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. PMID:27586767

  1. Books on acoustics

    NASA Astrophysics Data System (ADS)

    Shaw, Neil A.

    2001-05-01

    The legacy of a man is not limited to just his projects. His writings in many cases are a more lasting, and a definitely more accessible, monument. For 60 years, Leo L. Beranek has produced books on acoustics, acoustic measurements, sound control, music and architecture, noise and vibration control, concert halls, and opera houses in addition to teaching and consulting. His books are standard references and still cited in other books and in technical and professional articles. Many of his books were among, if not, the first comprehensive modern treatment of the subject and many are still foremost. A review of Dr. Beranek's many books as well as some anecdotes about the circumstances and consequences of same will be presented.

  2. Theory on acoustic sources

    NASA Technical Reports Server (NTRS)

    Wright, S. E.

    1978-01-01

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

  3. Acoustic velocity meter systems

    USGS Publications Warehouse

    Laenen, Antonius

    1985-01-01

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

  4. Structures and Acoustics Division

    NASA Technical Reports Server (NTRS)

    Acquaviva, Cynthia S.

    1999-01-01

    The Structures and Acoustics Division of NASA Glenn Research Center is an international leader in rotating structures, mechanical components, fatigue and fracture, and structural aeroacoustics. Included are disciplines related to life prediction and reliability, nondestructive evaluation, and mechanical drive systems. Reported are a synopsis of the work and accomplishments reported by the Division during the 1996 calendar year. A bibliography containing 42 citations is provided.

  5. Structures and Acoustics Division

    NASA Technical Reports Server (NTRS)

    Acquaviva, Cynthia S.

    2001-01-01

    The Structures and Acoustics Division of the NASA Glenn Research Center is an international leader in rotating structures, mechanical components, fatigue and fracture, and structural aeroacoustics. Included in this report are disciplines related to life prediction and reliability, nondestructive evaluation, and mechanical drive systems. Reported is a synopsis of the work and accomplishments completed by the Division during the 1997, 1998, and 1999 calendar years. A bibliography containing 93 citations is provided.

  6. Fast wideband acoustical holography.

    PubMed

    Hald, Jørgen

    2016-04-01

    Patch near-field acoustical holography methods like statistically optimized near-field acoustical holography and equivalent source method are limited to relatively low frequencies, where the average array-element spacing is less than half of the acoustic wavelength, while beamforming provides useful resolution only at medium-to-high frequencies. With adequate array design, both methods can be used with the same array. But for holography to provide good low-frequency resolution, a small measurement distance is needed, whereas beamforming requires a larger distance to limit sidelobe issues. The wideband holography method of the present paper was developed to overcome that practical conflict. Only a single measurement is needed at a relatively short distance and a single result is obtained covering the full frequency range. The method uses the principles of compressed sensing: A sparse sound field representation is assumed with a chosen set of basis functions, a measurement is taken with an irregular array, and the inverse problem is solved with a method that enforces sparsity in the coefficient vector. Instead of using regularization based on the 1-norm of the coefficient vector, an iterative solution procedure is used that promotes sparsity. The iterative method is shown to provide very similar results in most cases and to be computationally much more efficient. PMID:27106299

  7. Acoustic paramagnetic logging tool

    DOEpatents

    Vail, III, William B.

    1988-01-01

    New methods and apparatus are disclosed which allow measurement of the presence of oil and water in geological formations using a new physical effect called the Acoustic Paramagnetic Logging Effect (APLE). The presence of petroleum in formation causes a slight increase in the earth's magnetic field in the vicinity of the reservoir. This is the phenomena of paramagnetism. Application of an acoustic source to a geological formation at the Larmor frequency of the nucleons present causes the paramagnetism of the formation to disappear. This results in a decrease in the earth3 s magnetic field in the vicinity of the oil bearing formation. Repetitively frequency sweeping the acoustic source through the Larmor frequency of the nucleons present (approx. 2 kHz) causes an amplitude modulation of the earth's magnetic field which is a consequence of the APLE. The amplitude modulation of the earth's magnetic field is measured with an induction coil gradiometer and provides a direct measure of the amount of oil and water in the excitation zone of the formation . The phase of the signal is used to infer the longitudinal relaxation times of the fluids present, which results in the ability in general to separate oil and water and to measure the viscosity of the oil present. Such measurements may be preformed in open boreholes and in cased well bores.

  8. Acoustically enhanced heat transport.

    PubMed

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

    2016-01-01

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

  9. Acoustically enhanced heat transport

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  10. Spatiotemporally resolved granular acoustics

    NASA Astrophysics Data System (ADS)

    Owens, Eli; Daniels, Karen

    2011-03-01

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

  11. Off-axis photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Shelton, Ryan; Applegate, Brian E.

    2010-02-01

    Photoacoustic microscopy (PAM) is a high-contrast, high-resolution imaging modality used primarily for imaging hemoglobin and melanin. Important applications include mapping of the microvasculature and melanoma tumor margins. We have developed a novel photoacoustic microscope design, which substantially simplifies construction by enabling the use of unmodified commercial optics and ultrasonic transducers. Moreover, the simple design may be readily incorporated into a standard light microscope, thus providing a familiar imaging platform for clinical researchers. A proof-of-concept Off-Axis PAM system with a lateral resolution of 26 μm and a modest axial resolution of 410 μm has been assembled and characterized using tissue samples. We have derived the appropriate equations to describe the relevant design parameters and verified the equations via measurements made on our prototype Off-Axis PAM system. A consequence of the simple design is a reduction in axial resolution compared to coaxial designs. The reduction is inversely proportional to the cosine of the angle between excitation and detection and equal to 15% and 41% for angles of 30º and 45º, respectively. While resolution is negatively affected by off-axis detection, the ability to measure weak signals at depth is enhanced. Off-axis detection has an inherent dark-field quality; chromophores excited outside the numerical aperture of the ultrasonic detector will not be detected. The physical geometry of Off-Axis PAM enables the placement of the ultrasonic transducer at the minimum distance from the sample with no obstructions between the sample and transducer. This may prove to be an additional advantage of Off-Axis PAM over designs that incorporate long working distance ultrasonic transducers and/or require the propagation of the acoustic wave through the laser excitation optics to achieve co-axial detection.

  12. Interferometric synthetic aperture microscopy

    NASA Astrophysics Data System (ADS)

    Ralston, Tyler S.; Marks, Daniel L.; Scott Carney, P.; Boppart, Stephen A.

    2007-02-01

    State-of-the-art methods in high-resolution three-dimensional optical microscopy require that the focus be scanned through the entire region of interest. However, an analysis of the physics of the light-sample interaction reveals that the Fourier-space coverage is independent of depth. Here we show that, by solving the inverse scattering problem for interference microscopy, computed reconstruction yields volumes with a resolution in all planes that is equivalent to the resolution achieved only at the focal plane for conventional high-resolution microscopy. In short, the entire illuminated volume has spatially invariant resolution, thus eliminating the compromise between resolution and depth of field. We describe and demonstrate a novel computational image-formation technique called interferometric synthetic aperture microscopy (ISAM). ISAM has the potential to broadly impact real-time three-dimensional microscopy and analysis in the fields of cell and tumour biology, as well as in clinical diagnosis where in vivo imaging is preferable to biopsy.

  13. Nonlinear vibrational microscopy

    DOEpatents

    Holtom, Gary R.; Xie, Xiaoliang Sunney; Zumbusch, Andreas

    2000-01-01

    The present invention is a method and apparatus for microscopic vibrational imaging using coherent Anti-Stokes Raman Scattering or Sum Frequency Generation. Microscopic imaging with a vibrational spectroscopic contrast is achieved by generating signals in a nonlinear optical process and spatially resolved detection of the signals. The spatial resolution is attained by minimizing the spot size of the optical interrogation beams on the sample. Minimizing the spot size relies upon a. directing at least two substantially co-axial laser beams (interrogation beams) through a microscope objective providing a focal spot on the sample; b. collecting a signal beam together with a residual beam from the at least two co-axial laser beams after passing through the sample; c. removing the residual beam; and d. detecting the signal beam thereby creating said pixel. The method has significantly higher spatial resolution then IR microscopy and higher sensitivity than spontaneous Raman microscopy with much lower average excitation powers. CARS and SFG microscopy does not rely on the presence of fluorophores, but retains the resolution and three-dimensional sectioning capability of confocal and two-photon fluorescence microscopy. Complementary to these techniques, CARS and SFG microscopy provides a contrast mechanism based on vibrational spectroscopy. This vibrational contrast mechanism, combined with an unprecedented high sensitivity at a tolerable laser power level, provides a new approach for microscopic investigations of chemical and biological samples.

  14. Acoustic properties of triggered lightning

    NASA Astrophysics Data System (ADS)

    Dayeh, M. A.; Evans, N.; Ramaekers, J.; Trevino, J.; Rassoul, H.; Lucia, R. J.; Dwyer, J. R.; Uman, M. A.; Jordan, D. M.

    2014-12-01

    Acoustic signatures from rocket-triggered lightning are measured by a 15m long, one-dimensional microphone array consisting of 16 receivers situated 90 meters from the lightning channel. Measurements were taken at the International Center for Lightning Research and Testing (ICLRT) in Camp Blanding, FL during the summer of 2014. The linear array was oriented in an end-fire position so that the peak acoustic reception pattern can be steered vertically along the channel with a frequency-dependent spatial resolution, enabling us to sample the acoustic signatures from different portions along the lightning channel. We report on the characteristics of acoustic signatures associated with several return strokes in 6 measured flashes (total of 29 return strokes). In addition, we study the relationship between the amplitude, peak frequency, and inferred energy input of each stroke acoustic signature and the associated measured lightning parameters. Furthermore, challenges of obtaining acoustic measurements in thunderstorm harsh conditions and their countermeasures will also be discussed.

  15. Wireless Acoustic Measurement System

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  16. Wireless Acoustic Measurement System

    NASA Technical Reports Server (NTRS)

    Anderson, Paul D.; Dorland, Wade D.

    2005-01-01

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

  17. Imaging interferometric microscopy.

    PubMed

    Schwarz, Christian J; Kuznetsova, Yuliya; Brueck, S R J

    2003-08-15

    We introduce and demonstrate a new microscopy concept: imaging interferometric microscopy (IIM), which is related to holography, synthetic-aperture imaging, and off-axis-dark-field illumination techniques. IIM is a wavelength-division multiplex approach to image formation that combines multiple images covering different spatial-frequency regions to form a composite image with a resolution much greater than that permitted by the same optical system using conventional techniques. This new type of microscopy involves both off-axis coherent illumination and reinjection of appropriate zero-order reference beams. Images demonstrate high resolution, comparable with that of a high-numerical-aperture (NA) objective, while they retain the long working distance, the large depth of field, and the large field of view of a low-NA objective. A Fourier-optics model of IIM is in good agreement with the experiment. PMID:12943079

  18. Multiphoton microscopy in neuroscience

    NASA Astrophysics Data System (ADS)

    Denk, Winfried

    2002-06-01

    The study of the nervous system requires to an exceptional extent observation of and experimentation on intact tissue. There, in particular, high-resolution optical microscopy benefits from the inherent advantages of multi-photon fluorescence excitation. Several cases will be presented from a number of different tissues and organisms, where multi-photon excited laser scanning fluorescence microscopy has been an essential experimental tool. Those examples include the discovery of biochemical coincidence detection in synaptic spines and the clarification of the underlying mechanism; the observation of sensory evoked dendritic signaling in intact animals and the observation of light induced calcium signals in the intact retina. Recently a fiber coupled two-photon microscopy has been developed that allows the imaging in moving animal.

  19. Controllable tomography phase microscopy

    NASA Astrophysics Data System (ADS)

    Xiu, Peng; Zhou, Xin; Kuang, Cuifang; Xu, Yingke; Liu, Xu

    2015-03-01

    Tomography phase microscopy (TPM) is a new microscopic method that can quantitatively yield the volumetric 3D distribution of a sample's refractive index (RI), which is significant for cell biology research. In this paper, a controllable TPM system is introduced. In this system a circulatory phase-shifting method and piezoelectric ceramic are used which enable the TPM system to record the 3D RI distribution at a more controllable speed, from 1 to 40 fps, than in the other TPM systems reported. The resolution of the RI distribution obtained by this controllable TPM is much better than that in images recorded by phase contrast microscopy and interference tomography microscopy. The realization of controllable TPM not only allows for the application of TPM to the measurement of kinds of RI sample, but also contributes to academic and technological support for the practical use of TPM.

  20. Acoustic nonlinearity in dispersive solids

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Yost, William T.

    1991-01-01

    An investigation to consider the effects of dispersion on the generation of the static acoustic wave component is presented. It is considered that an acoustic toneburst may be modeled as a modulated continuous waveform and that the generated initial static displacement pulse may be viewed as a modulation-confined disturbance. A theoretical model for the generation of the acoustic modulation solitons evolved is developed and experimental evidence in samples of vitreous silica demonstrating the essential validity of the model is provided.

  1. Spacecraft Internal Acoustic Environment Modeling

    NASA Technical Reports Server (NTRS)

    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.

  2. Truck acoustic data analyzer system

    DOEpatents

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

    2006-07-04

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

  3. Transition section for acoustic waveguides

    DOEpatents

    Karplus, H.H.B.

    1975-10-28

    A means of facilitating the transmission of acoustic waves with minimal reflection between two regions having different specific acoustic impedances is described comprising a region exhibiting a constant product of cross-sectional area and specific acoustic impedance at each cross-sectional plane along the axis of the transition region. A variety of structures that exhibit this feature is disclosed, the preferred embodiment comprising a nested structure of doubly reentrant cones. This structure is useful for monitoring the operation of nuclear reactors in which random acoustic signals are generated in the course of operation.

  4. Guided acoustic wave inspection system

    DOEpatents

    Chinn, Diane J.

    2004-10-05

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

  5. Monitoring photodynamic therapy with photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Shao, Peng; Chapman, David W.; Moore, Ronald B.; Zemp, Roger J.

    2015-10-01

    We present our work on examining the feasibility of monitoring photodynamic therapy (PDT)-induced vasculature change with acoustic-resolution photoacoustic microscopy (PAM). Verteporfin, an FDA-approved photosensitizer for clinical PDT, was utilized. With a 60-μm-resolution PAM system, we demonstrated the capability of PAM to monitor PDT-induced vasculature variations in a chick chorioallantoic membrane model with topical application and in a rat ear with intravenous injection of the photosensitizer. We also showed oxygen saturation change in target blood vessels due to PDT. Success of the present approach may potentially lead to the application of PAM imaging in evaluating PDT efficacy, guiding treatment, and predicting responders from nonresponders.

  6. Powered-Lift Aerodynamics and Acoustics. [conferences

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Powered lift technology is reviewed. Topics covered include: (1) high lift aerodynamics; (2) high speed and cruise aerodynamics; (3) acoustics; (4) propulsion aerodynamics and acoustics; (5) aerodynamic and acoustic loads; and (6) full-scale and flight research.

  7. Ares I Scale Model Acoustic Test Lift-Off Acoustics

    NASA Technical Reports Server (NTRS)

    Counter, Douglas D.; Houston, Janie D.

    2011-01-01

    The lift-off acoustic (LOA) environment is an important design factor for any launch vehicle. For the Ares I vehicle, the LOA environments were derived by scaling flight data from other launch vehicles. The Ares I LOA predicted environments are compared to the Ares I Scale Model Acoustic Test (ASMAT) preliminary results.

  8. Video Telescope Operating Microscopy.

    PubMed

    Divers, Stephen J

    2015-09-01

    Exotic pet veterinarians frequently have to operate on small animals, and magnification is commonly used. Existing endoscopy equipment can be used with a mechanical arm and telescope to enable video telescope operating microscopy. The additional equipment items and their specifics are described, and several case examples are provided. PMID:26117519

  9. Photoacoustic computed microscopy

    NASA Astrophysics Data System (ADS)

    Yao, Lei; Xi, Lei; Jiang, Huabei

    2014-05-01

    Photoacoustic microscopy (PAM) is emerging as a powerful technique for imaging microvasculature at depths beyond the ~1 mm depth limit associated with confocal microscopy, two-photon microscopy and optical coherence tomography. PAM, however, is currently qualitative in nature and cannot quantitatively measure important functional parameters including oxyhemoglobin (HbO2), deoxyhemoglobin (HbR), oxygen saturation (sO2), blood flow (BF) and rate of oxygen metabolism (MRO2). Here we describe a new photoacoustic microscopic method, termed photoacoustic computed microscopy (PACM) that combines current PAM technique with a model-based inverse reconstruction algorithm. We evaluate the PACM approach using tissue-mimicking phantoms and demonstrate its in vivo imaging ability of quantifying HbO2, HbR, sO2, cerebral BF and cerebral MRO2 at the small vessel level in a rodent model. This new technique provides a unique tool for neuroscience research and for visualizing microvasculature dynamics involved in tumor angiogenesis and in inflammatory joint diseases.

  10. Interferometric synthetic aperture microscopy

    NASA Astrophysics Data System (ADS)

    Ralston, Tyler S.

    State-of-the-art interferometric microscopies have problems representing objects that lie outside of the focus because the defocus and diffraction effects are not accounted for in the processing. These problems occur because of the lack of comprehensive models to include the scattering effects in the processing. In this dissertation, a new modality in three-dimensional (3D) optical microscopy, Interferometric Synthetic Aperture Microscopy (ISAM), is introduced to account for the scattering effects. Comprehensive models for interferometric microscopy, such as optical coherence tomography (OCT) are developed, for which forward, adjoint, normal, and inverse operators are formulated. Using an accurate model for the probe beam, the resulting algorithms demonstrate accurate linear estimation of the susceptibility of an object from the interferometric data. Using the regularized least squares solution, an ISAM reconstruction of underlying object structure having spatially invariant resolution is obtained from simulated and experimental interferometric data, even in regions outside of the focal plane of the lens. Two-dimensional (2D) and 3D interferometric data is used to resolve objects outside of the confocal region with minimal loss of resolution, unlike in OCT. Therefore, high-resolution details are recovered from outside of the confocal region. Models and solutions are presented for the planar-scanned, the rotationally scanned, and the full-field illuminated geometry. The models and algorithms presented account for the effects of a finite beam width, the source spectrum, the illumination and collection fields, as well as defocus, diffraction and dispersion effects.

  11. Acoustic Mechanical Feedthroughs

    NASA Technical Reports Server (NTRS)

    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

  12. Dynamic acoustic tractor beams

    NASA Astrophysics Data System (ADS)

    Mitri, F. G.

    2015-03-01

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

  13. The acoustics of snoring.

    PubMed

    Pevernagie, Dirk; Aarts, Ronald M; De Meyer, Micheline

    2010-04-01

    Snoring is a prevalent disorder affecting 20-40% of the general population. The mechanism of snoring is vibration of anatomical structures in the pharyngeal airway. Flutter of the soft palate accounts for the harsh aspect of the snoring sound. Natural or drug-induced sleep is required for its appearance. Snoring is subject to many influences such as body position, sleep stage, route of breathing and the presence or absence of sleep-disordered breathing. Its presentation may be variable within or between nights. While snoring is generally perceived as a social nuisance, rating of its noisiness is subjective and, therefore, inconsistent. Objective assessment of snoring is important to evaluate the effect of treatment interventions. Moreover, snoring carries information relating to the site and degree of obstruction of the upper airway. If evidence for monolevel snoring at the site of the soft palate is provided, the patient may benefit from palatal surgery. These considerations have inspired researchers to scrutinize the acoustic characteristics of snoring events. Similarly to speech, snoring is produced in the vocal tract. Because of this analogy, existing techniques for speech analysis have been applied to evaluate snoring sounds. It appears that the pitch of the snoring sound is in the low-frequency range (<500 Hz) and corresponds to a fundamental frequency with associated harmonics. The pitch of snoring is determined by vibration of the soft palate, while nonpalatal snoring is more 'noise-like', and has scattered energy content in the higher spectral sub-bands (>500 Hz). To evaluate acoustic properties of snoring, sleep nasendoscopy is often performed. Recent evidence suggests that the acoustic quality of snoring is markedly different in drug-induced sleep as compared with natural sleep. Most often, palatal surgery alters sound characteristics of snoring, but is no cure for this disorder. It is uncertain whether the perceived improvement after palatal surgery, as

  14. Quantum positron acoustic waves

    SciTech Connect

    Metref, Hassina; Tribeche, Mouloud

    2014-12-15

    Nonlinear quantum positron-acoustic (QPA) waves are investigated for the first time, within the theoretical framework of the quantum hydrodynamic model. In the small but finite amplitude limit, both deformed Korteweg-de Vries and generalized Korteweg-de Vries equations governing, respectively, the dynamics of QPA solitary waves and double-layers are derived. Moreover, a full finite amplitude analysis is undertaken, and a numerical integration of the obtained highly nonlinear equations is carried out. The results complement our previously published results on this problem.

  15. Wind turbine acoustics

    NASA Technical Reports Server (NTRS)

    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.

  16. Dynamic acoustic tractor beams

    SciTech Connect

    Mitri, F. G.

    2015-03-07

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

  17. North Pacific Acoustic Laboratory.

    PubMed

    Worcester, Peter F; Spindel, Robert C

    2005-03-01

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

  18. Scanning Probe Microscopy and Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wiesendanger, Roland

    1994-09-01

    Preface; List of acronyms; Introduction; Part I. Experimental Methods and Theoretical Background of Scanning Probe Microscopy and Spectroscopy: 1. Scanning tunnelling microscopy; 2. Scanning force microscopy; 3. Related scanning probe techniques; Part II. Applications of Scanning Probe Microscopy and Spectroscopy: 4. Condensed matter physics; 5. Chemistry; 6. Organic materials; 7. Metrology and standards; 8. Nanotechnology; References; Index.

  19. Quantitative measurement of nanomechanical properties in composite materials

    NASA Astrophysics Data System (ADS)

    Zhao, Wei

    In this work, quantitative Atomic force acoustic microscopy (AFAM) was used to measure nanomechanical properties and to determine microstructural morphology in fiber reinforced composites and hard calcified tissue. In carbon fiber reinforced composites, the fiber-matrix interphase is of interest as it affects the primary load-transfer process and thereby bulk mechanical properties of reinforced composites. The study of properties in the interphase region is important for an understanding of the bulk mechanical properties, which have been shown affected by moisture-based environmental degradation. Single point AFAM testing has been used to quantitatively determine elastic properties at the fiber-matrix interphase by taking advantage of the high spatial scanning resolution capable of measuring interphase dimensions. Carbon-fiber epoxy composite samples were degraded in laboratory conditions by exposure to a accelerated hydrothermal degradation environment in deionized water and salt water. Composite degradation has been characterized by the change in the epoxy matrix contact stiffness and the interphase properties. A decrease in matrix stiffness was found to coincide with the environmental exposure and moisture absorption of the samples. Interphase stiffness measurements indicate a constant interphase thickness as a function of environmental exposure. Chemical analysis of the epoxy using FTIR and Raman spectroscopy indicate hydrolysis of the C-O-C and Epoxide bonds which contribute to the decrease in epoxy mechanical properties. Accelerated degradation by salt water and deionized water both resulted in degradation of the epoxy, though the presence of sodium chloride showed less degradation. From SEM, debonding of the fiber-matrix interface was observed to be more severe when exposed to a salt water environment. In performing quantitative AFAM measurements, the effects of tip shape on the contact mechanics at the epoxy interface were found to influence the reported

  20. Digital Controller For Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Tarver, D. Kent

    1989-01-01

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

  1. Acoustical Environment for Academic Buildings.

    ERIC Educational Resources Information Center

    Lortie, L.J.

    Discussion of the parameters governing noise control and room acoustics are followed by a demonstration on how to achieve a good acoustical environment. Topics emphasized include--(1) design and control objectives, (2) noise sources and propagation, (3) reverberation parameters, (4) noise control factors and parameters, and (5) sound systems. Also…

  2. Acoustic Emissions Reveal Combustion Conditions

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    Turbulent-flame acoustic emissions change with air/fuel ratio variations. Acoustic emissions sensed and processed to detect inefficient operation; control system responds by adjusting fuel/air mixture for greater efficiency. Useful for diagnosis of combustion processes and fuel/air control.

  3. Electronic dummy for acoustical testing

    NASA Technical Reports Server (NTRS)

    Bauer, B. B.; Di Mattia, A. L.; Rosencheck, A. J.; Stern, M.; Torick, E. L.

    1967-01-01

    Electronic Dummy /ED/ used for acoustical testing represents the average male torso from the Xiphoid process upward and includes an acoustic replica of the human head. This head simulates natural flesh, and has an artificial voice and artificial ears that measure sound pressures at the eardrum or the entrance to the ear canal.

  4. Sound Advice on Classroom Acoustics.

    ERIC Educational Resources Information Center

    Sturgeon, Julie

    2003-01-01

    Discusses the importance of acoustic standards in classroom design, presenting an interview with the Acoustical Society of America's (ASA's) standards manager which focuses on reasons for the new ASA standards, the standards document (which was written for K-12 classroom but applies to college classrooms), the need to avoid echo and be able to…

  5. Acoustic Similarity and Dichotic Listening.

    ERIC Educational Resources Information Center

    Benson, Peter

    1978-01-01

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

  6. Characterization of Acoustic Droplet Vaporization Using MRI

    NASA Astrophysics Data System (ADS)

    Li, David; Allen, Steven; Hernandez-Garcia, Luis; Bull, Joseph

    2013-11-01

    Acoustic droplet vaporization (ADV) is the selective vaporization of liquid droplets to form larger gas bubbles. The ADV process is currently being researched for biomedical applications such as gas embolotherapy, drug delivery, and phase-change contrast agents. In this study an albumin encapsulated dodecafluoropentane (DDFP, CAS: 678-26-2) microdroplet suspension was vaporized using a single element focused (f/2, D = 19 mm) 3.5 MHz transducer (Panametrics A321S, Olympus, Waltham, MA). The resulting DDFP bubble clouds were imaged using both bright field microscopy and MRI (Varian 7T, Agilent Technologies Inc., Santa Clara, CA). Field distortions due to DDFP bubble generation were characterized against the bright field images as a function of acoustic power and bubble cloud size. Experimentally a direct correlation between bubble cloud dimensions generated and field distortions seen in the MRI was observed. Additionally, MR velocimetry was used to measure the flow field resulting from ADV. The field distortions due to the bubbles were further characterized by modeling Maxwell's equations using COMSOL (COMSOL Inc., Burlington, MA). The ability to characterize ADV with alternative imaging modalities may prove useful in further development of ADV based biomedical therapies.

  7. Acoustical sensing of cardiomyocyte cluster beating.

    PubMed

    Tymchenko, Nina; Kunze, Angelika; Dahlenborg, Kerstin; Svedhem, Sofia; Steel, Daniella

    2013-06-14

    Spontaneously beating human pluripotent stem cell-derived cardiomyocytes clusters (CMCs) represent an excellent in vitro tool for studies of human cardiomyocyte function and for pharmacological cardiac safety assessment. Such testing typically requires highly trained operators, precision plating, or large cell quantities, and there is a demand for real-time, label-free monitoring of small cell quantities, especially rare cells and tissue-like structures. Array formats based on sensing of electrical or optical properties of cells are being developed and in use by the pharmaceutical industry. A potential alternative to these techniques is represented by the quartz crystal microbalance with dissipation monitoring (QCM-D) technique, which is an acoustic surface sensitive technique that measures changes in mass and viscoelastic properties close to the sensor surface (from nm to μm). There is an increasing number of studies where QCM-D has successfully been applied to monitor properties of cells and cellular processes. In the present study, we show that spontaneous beating of CMCs on QCM-D sensors can be clearly detected, both in the frequency and the dissipation signals. Beating rates in the range of 66-168 bpm for CMCs were detected and confirmed by simultaneous light microscopy. The QCM-D beating profile was found to provide individual fingerprints of the hPS-CMCs. The presented results point towards acoustical assays for evaluation cardiotoxicity. PMID:23643814

  8. Opto-acoustic thrombolysis

    DOEpatents

    Celliers, Peter; Da Silva, Luiz; Glinsky, Michael; London, Richard; Maitland, Duncan; Matthews, Dennis; Fitch, Pat

    2000-01-01

    This invention is a catheter-based device for generating an ultrasound excitation in biological tissue. Pulsed laser light is guided through an optical fiber to provide the energy for producing the acoustic vibrations. The optical energy is deposited in a water-based absorbing fluid, e.g. saline, thrombolytic agent, blood or thrombus, and generates an acoustic impulse in the fluid through thermoelastic and/or thermodynamic mechanisms. By pulsing the laser at a repetition rate (which may vary from 10 Hz to 100 kHz) an ultrasonic radiation field can be established locally in the medium. This method of producing ultrasonic vibrations can be used in vivo for the treatment of stroke-related conditions in humans, particularly for dissolving thrombus or treating vasospasm. The catheter can also incorporate thrombolytic drug treatments as an adjunct therapy and it can be operated in conjunction with ultrasonic detection equipment for imaging and feedback control and with optical sensors for characterization of thrombus type and consistency.

  9. Musical acoustics demonstrations

    NASA Astrophysics Data System (ADS)

    Hoekje, P. L.

    2003-10-01

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

  10. Acoustic source localization.

    PubMed

    Kundu, Tribikram

    2014-01-01

    In this article different techniques for localizing acoustic sources are described and the advantages/disadvantages of these techniques are discussed. Some source localization techniques are restricted to isotropic structures while other methods can be applied to anisotropic structures as well. Some techniques require precise knowledge of the direction dependent velocity profiles in the anisotropic body while other techniques do not require that knowledge. Some methods require accurate values of the time of arrival of the acoustic waves at the receivers while other techniques can function without that information. Published papers introducing various techniques emphasize the advantages of the introduced techniques while ignoring and often not mentioning the limitations and weaknesses of the new techniques. What is lacking in the literature is a comprehensive review and comparison of the available techniques; this article attempts to do that. After reviewing various techniques the paper concludes which source localization technique should be most effective for what type of structure and what the current research needs are. PMID:23870388

  11. MEMS Based Acoustic Array

    NASA Technical Reports Server (NTRS)

    Sheplak, Mark (Inventor); Nishida, Toshikaza (Inventor); Humphreys, William M. (Inventor); Arnold, David P. (Inventor)

    2006-01-01

    Embodiments of the present invention described and shown in the specification aid drawings include a combination responsive to an acoustic wave that can be utilized as a dynamic pressure sensor. In one embodiment of the present invention, the combination has a substrate having a first surface and an opposite second surface, a microphone positioned on the first surface of the substrate and having an input and a first output and a second output, wherein the input receives a biased voltage, and the microphone generates an output signal responsive to the acoustic wave between the first output and the second output. The combination further has an amplifier positioned on the first surface of the substrate and having a first input and a second input and an output, wherein the first input of the amplifier is electrically coupled to the first output of the microphone and the second input of the amplifier is electrically coupled to the second output of the microphone for receiving the output sinual from the microphone. The amplifier is spaced from the microphone with a separation smaller than 0.5 mm.

  12. Acoustic particle acceleration sensors

    SciTech Connect

    Franklin, J.B.; Barry, P.J.

    1996-04-01

    A crossed dipole array provides a directional receiving capability in a relatively small sensor package and is therefore very attractive for many applications in acoustics. Particle velocity measurements on two axes perpendicular to each other are required to provide the dipole signals. These can be obtained directly using particle velocity sensors or via simple transfer functions using acceleration and displacement sensors. Also, the derivative of the acoustic pressure with respect to space provides a signal proportional to the particle acceleration and gives rise to the pressure gradient sensor. Each of these sensors has strengths and drawbacks depending on the frequency regime of interest, the noise background, and whether a point or a line configuration of dipole sensors is desired. In this paper, the performance of acceleration sensors is addressed using a sensor concept developed at DREA. These sensors exploit bending stresses in a cantilever beam of piezoelectric material to obtain wide bandwidth and high sensitivity. Models which predict the acceleration sensitivity, pressure sensitivity, and natural frequency for this type of sensor are described. Experimental results obtained using several different versions of these sensors are presented and compared with theory. The predicted performance of acceleration sensors are compared with that of pressure gradient arrays and particle velocity sensors. {copyright} {ital 1996 American Institute of Physics.}

  13. Opto-acoustic thrombolysis

    SciTech Connect

    Celliers, P.; Silva, L. Da; Glinsky, M.; London, R.; Maitland, D.; Matthews, D.; Fitch, P.

    2000-02-08

    This invention is a catheter-based device for generating an ultrasound excitation in biological tissue. Pulsed laser light is guided through an optical fiber to provide the energy for producing the acoustic vibrations. The optical energy is deposited in a water-based absorbing fluid, e.g. saline, thrombolytic agent, blood or thrombus, and generates an acoustic impulse in the fluid through thermoelastic and/or thermodynamic mechanisms. By pulsing the laser at a repetition rate (which may vary from 10 Hz to 100 kHz) an ultrasonic radiation field can be established locally in the medium. This method of producing ultrasonic vibrations can be used in vivo for the treatment of stroke-related conditions in humans, particularly for dissolving thrombus or treating vasospasm. The catheter can also incorporate thrombolytic drug treatments as an adjunct therapy and it can be operated in conjunction with ultrasonic detection equipment for imaging and feedback control and with optical sensors for characterization of thrombus type and consistency.

  14. Acoustic emission linear pulse holography

    DOEpatents

    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.

  15. Acoustic Absorption in Porous Materials

    NASA Technical Reports Server (NTRS)

    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.

  16. Dynamic Transmission Electron Microscopy

    SciTech Connect

    Evans, James E.; Jungjohann, K. L.; Browning, Nigel D.

    2012-10-12

    Dynamic transmission electron microscopy (DTEM) combines the benefits of high spatial resolution electron microscopy with the high temporal resolution of ultrafast lasers. The incorporation of these two components into a single instrument provides a perfect platform for in situ observations of material processes. However, previous DTEM applications have focused on observing structural changes occurring in samples exposed to high vacuum. Therefore, in order to expand the pump-probe experimental regime to more natural environmental conditions, in situ gas and liquid chambers must be coupled with Dynamic TEM. This chapter describes the current and future applications of in situ liquid DTEM to permit time-resolved atomic scale observations in an aqueous environment, Although this chapter focuses mostly on in situ liquid imaging, the same research potential exists for in situ gas experiments and the successful integration of these techniques promises new insights for understanding nanoparticle, catalyst and biological protein dynamics with unprecedented spatiotemporal resolution.

  17. Quad stereo-microscopy

    NASA Astrophysics Data System (ADS)

    Hay, Rebecca F.; Gibson, Graham M.; Lee, Michael P.; Padgett, Miles J.; Phillips, David B.

    2014-09-01

    Stereo-microscopy is a technique that enables a sample to be imaged from two directions simultaneously, allowing the tracking of microscopic objects in three dimensions. This is achieved by illuminating the sample from different directions, each illumination direction producing an individual image. These images are superimposed in the image plane but can be easily separated using a diffractive optical element in the Fourier plane of the imaging arm. Therefore this enables 3-dimensional coordinates to be reconstructed using simple 2-dimensional image tracking and parallax. This is a powerful technique when combined with holographic optical tweezers (HOT), where multiple objects can be trapped and tracked simultaneously in three dimensions. In this work, we extend this concept to four different illumination directions: quad stereo-microscopy. This allows us to measure the accuracy of tracking in three dimensions, and to optimise the system.

  18. Multimodal Nonlinear Optical Microscopy

    PubMed Central

    Yue, Shuhua; Slipchenko, Mikhail N.; Cheng, Ji-Xin

    2013-01-01

    Because each nonlinear optical (NLO) imaging modality is sensitive to specific molecules or structures, multimodal NLO imaging capitalizes the potential of NLO microscopy for studies of complex biological tissues. The coupling of multiphoton fluorescence, second harmonic generation, and coherent anti-Stokes Raman scattering (CARS) has allowed investigation of a broad range of biological questions concerning lipid metabolism, cancer development, cardiovascular disease, and skin biology. Moreover, recent research shows the great potential of using CARS microscope as a platform to develop more advanced NLO modalities such as electronic-resonance-enhanced four-wave mixing, stimulated Raman scattering, and pump-probe microscopy. This article reviews the various approaches developed for realization of multimodal NLO imaging as well as developments of new NLO modalities on a CARS microscope. Applications to various aspects of biological and biomedical research are discussed. PMID:24353747

  19. Scanning Electrochemical Microscopy

    NASA Astrophysics Data System (ADS)

    Amemiya, Shigeru; Bard, Allen J.; Fan, Fu-Ren F.; Mirkin, Michael V.; Unwin, Patrick R.

    2008-07-01

    This review describes work done in scanning electrochemical microscopy (SECM) since 2000 with an emphasis on new applications and important trends, such as nanometer-sized tips. SECM has been adapted to investigate charge transport across liquid/liquid interfaces and to probe charge transport in thin films and membranes. It has been used in biological systems like single cells to study ion transport in channels, as well as cellular and enzyme activity. It is also a powerful and useful tool for the evaluation of the electrocatalytic activities of different materials for useful reactions, such as oxygen reduction and hydrogen oxidation. SECM has also been used as an electrochemical tool for studies of the local properties and reactivity of a wide variety of materials, including metals, insulators, and semiconductors. Finally, SECM has been combined with several other nonelectrochemical techniques, such as atomic force microscopy, to enhance and complement the information available from SECM alone.

  20. Ion photon emission microscopy

    NASA Astrophysics Data System (ADS)

    Rossi, P.; Doyle, B. L.; Banks, J. C.; Battistella, A.; Gennaro, G.; McDaniel, F. D.; Mellon, M.; Vittone, E.; Vizkelethy, G.; Wing, N. D.

    2003-09-01

    A new ion-induced emission microscopy has been invented and demonstrated, which is called ion photon emission microscopy (IPEM). It employs a low current, broad ion beam impinging on a sample, previously coated or simply covered with a few microns of a fast, highly efficient phosphor layer. The light produced at the single ion impact point is collected with an optical microscope and projected at high magnification onto a single photon position sensitive detector (PSD). This allows maps of the ion strike effects to be produced, effectively removing the need for a microbeam. Irradiation in air and even the use of alpha particle sources with no accelerator are possible. Potential applications include ion beam induced charge collection studies of semiconducting and insulating materials, single event upset studies on microchips and even biological cells in radiobiological effectiveness experiments. We describe the IPEM setup, including a 60× OM-40 microscope with a 1.5 mm hole for the beam transmission and a Quantar PSD with 60 μm pixel. Bicron plastic scintillator blades of 10 μm were chosen as a phosphor for their nanosecond time resolution, homogeneity, utility and commercial availability. The results given in this paper are for a prototype IPEM system. They indicate a resolution of ˜12 μm, the presence of a spatial halo and a He-ion efficiency of ˜20%. This marks the first time that nuclear microscopy has been performed with a radioactive source.

  1. Dual-CARS microscopy

    NASA Astrophysics Data System (ADS)

    Enejder, Annika; Brackmann, Christian; Burkacky, Ondrej; Åkeson, Madeleine

    2007-02-01

    We present a new Coherent Anti-Stokes Raman Scattering (CARS) microscopy technique for label-free imaging of biomolecules in living cells; dual-CARS microscopy. The use of three synchronized laser pulses in a dual-pump/dualdetection configuration enables imaging of two species with different molecular vibrations simultaneously, as well as acquisition of images free of non-resonant background. We show the power of the method by imaging deuterated nonadecane slowly diffusing into a suspension of living yeast cells in medium, clearly distinguishing the medium and the lipid droplets in the cells by probing the CH II vibration from the D-nonadecane by probing the CD vibration. In addition, images of lipid stores in living C. elegans nematodes free of non-resonant background are shown. This results in a significant enhancement of the image contrast, allowing the visualization of emerging, low-density lipid stores in a dauer larva, difficult to distinguish in conventional CARS microscopy. The separation of the non-resonant background is shown to be beneficial also when monitoring molecules with weak vibrational modes. The improved sensitivity obtained is illustrated by probing the C=C vibration in polyunsaturated lipids extracted from fish. This enables the monitoring of the degree of unsaturation of lipids, a high value of which is reported in foods known to have positive effects on human health.

  2. The acoustic vector sensor: a versatile battlefield acoustics sensor

    NASA Astrophysics Data System (ADS)

    de Bree, Hans-Elias; Wind, Jelmer W.

    2011-06-01

    The invention of the Microflown sensor has made it possible to measure acoustic particle velocity directly. An acoustic vector sensor (AVS) measures the particle velocity in three directions (the source direction) and the pressure. The sensor is a uniquely versatile battlefield sensor because its size is a few millimeters and it is sensitive to sound from 10Hz to 10kHz. This article shows field tests results of acoustic vector sensors, measuring rifles, heavy artillery, fixed wing aircraft and helicopters. Experimental data shows that the sensor is suitable as a ground sensor, mounted on a vehicle and on a UAV.

  3. Multimaterial Acoustic Fibers

    NASA Astrophysics Data System (ADS)

    Chocat, Noemie

    The emergence of multimaterial fibers that combine a multiplicity of solid materials with disparate electrical, optical, and mechanical properties into a single fiber presents new opportunities for extending fiber applications well beyond optical transmission. Fiber reflectors, thermal detectors, photodetectors, chemical sensors, surface-emitting fiber lasers, fiber diodes, and other functional fiber devices have been demonstrated with this approach. Yet, throughout this development and indeed the development of fibers in general, a key premise has remained unchanged : that fibers are essentially static devices incapable of controllably changing their properties at high frequencies. Unique opportunities would arise if a rapid, electrically-driven mechanism for changing fiber properties existed. A wide spectrum of hitherto passive fiber devices could at once become active with applications spanning electronics, mechanics, acoustics, and optics, with the benefits of large surface-area, structural robustness, and mechanical flexibility. This thesis addresses the challenges and opportunities associated with the realization of electromechanical transduction in fibers through the integration of internal piezoelectric and electrostrictive domains. The fundamental challenges related to the fabrication of piezoelectric devices in fiber form are analyzed from a materials perspective, and candidate materials and geometries are selected that are compatible with the thermal drawing process. The first realization of a thermally drawn piezoelectric fiber device is reported and its piezoelectric response is established over a wide range of frequencies. The acoustic properties of piezoelectric fiber devices are characterized and related to their mechanical and geometric properties. Collective effects in multi-fiber constructs are discussed and demonstrated by the realization of a linear phased array of piezoelectric fibers capable of acoustic beam steering. High strain actuation

  4. PORTABLE ACOUSTIC MONITORING PACKAGE (PAMP)

    SciTech Connect

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

    2004-07-20

    The Portable Acoustic Monitoring Package (PAMP) has been designed to record and monitor the acoustic signal in natural gas transmission lines. In particular the three acoustic signals associated with a line leak. The system is portable ({approx}30 lbs) and is designed for line pressures up to 1000 psi. It has become apparent that cataloging of the various background acoustic signals in natural gas transmission line is very important if a system to identify leak signals is to be developed. The low-pressure (0-200 psig) laboratory test phase has been completed and a number of field trials have been conducted. Before the cataloging phase could begin, a few problems identified in field trials identified had to be corrected such as: (1) Decreased microphone sensitivity at line pressures above 250 psig. (2) The inability to deal with large data sets collected when cataloging the variety of signals in a transmission line. (3) The lack of an available online acoustic calibration system. These problems have been solved and the WVU PAMP is now fully functional over the entire pressure range found in the Natural Gas transmission lines in this region. Field portability and reliability have been greatly improved. Data collection and storage have also improved to the point were the full acoustic spectrum of acoustic signals can be accurately cataloged, recorded and described.

  5. Turbofan Acoustic Propagation and Radiation

    NASA Technical Reports Server (NTRS)

    Eversman, Walter

    2000-01-01

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

  6. Controlling sound with acoustic metamaterials

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  7. Electromagnetic acoustic transducer

    DOEpatents

    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.

  8. Acoustic effects of sprays

    NASA Technical Reports Server (NTRS)

    Pindera, Maciej Z.; Przekwas, Andrzej J.

    1994-01-01

    Since the early 1960's, it has been known that realistic combustion models for liquid fuel rocket engines should contain at least a rudimentary treatment of atomization and spray physics. This is of particular importance in transient operations. It has long been recognized that spray characteristics and droplet vaporization physics play a fundamental role in determining the stability behavior of liquid fuel rocket motors. This paper gives an overview of work in progress on design of a numerical algorithm for practical studies of combustion instabilities in liquid rocket motors. For flexibility, the algorithm is composed of semi-independent solution modules, accounting for different physical processes. Current findings are report and future work is indicated. The main emphasis of this research is the development of an efficient treatment to interactions between acoustic fields and liquid fuel/oxidizer sprays.

  9. Progress in acoustic holography

    NASA Astrophysics Data System (ADS)

    Hildebrand, B. P.

    1985-01-01

    The theory underlying the methods used in acoustic holography (the real-time liquid surface levitation and the scanning holography methods) and in electromagnetic holography, which uses electromagnetic impulses (radar) or electromagnetic waves (eddy current) is developed. These holographic techniques are illustrated with experimental results, including the use of the liquid surface levitation method for inspecting fiberglass laminate tubes, and examples of the time-of-flight holographic images, the coherent ultrasonic images, multifrequency ultrasonic images, and the synthetic aperture holography images obtained by the use of the scanning holography methodology. Other examples illustrate applications of radar holography and eddy current holography. These examples are used to refute some traditional negative comments on nonoptical holography.

  10. Wind turbine acoustic standards

    NASA Technical Reports Server (NTRS)

    Stephens, D. G.; Shepherd, K. P.; Grosveld, F.

    1981-01-01

    A program is being conducted to develop noise standards for wind turbines which minimize annoyance and which can be used to design specifications. The approach consists of presenting wind turbine noise stimuli to test subjects in a laboratory listening chamber. The responses of the subjects are recorded for a range of stimuli which encompass the designs, operating conditions, and ambient noise levels of current and future installations. Results to date have established the threshold of detectability for a range of impulsive stimuli of the type associated with blade/tower wake interactions. The status of the ongoing psychoacoustic tests, the subjective data, and the approach to the development of acoustic criteria/standards are described.

  11. Acoustic fault injection tool (AFIT)

    NASA Astrophysics Data System (ADS)

    Schoess, Jeffrey N.

    1999-05-01

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

  12. Detachable acoustic electric feedthrough

    NASA Astrophysics Data System (ADS)

    Moss, Scott; Skippen, Jeremy; Konak, Michael; Powlesland, Ian; Galea, Steve

    2010-04-01

    This paper outlines the development and characterisation of a detachable acoustic electric feedthrough (DAEF) to transfer power and data across a metal (or composite) plate. The DAEF approach is being explored as a potential means of wirelessly powering in-situ structural health monitoring systems embedded within aircraft and other high value engineering assets. The DAEF technique operates via two axially aligned piezoelectric-magnet structures mounted on opposite sides of a plate. Magnetic force is used to align the two piezoelectric-magnet structures, to create an acoustic path across a plate. The piezoelectric-magnet structures consisted of Pz26 piezoelectric disk elements bonded to NdFeB magnets, with a standard ultrasonic couplant (High-Z) used between the magnet and plate to facilitate the passage of ultrasound. Measured impedance curves are matched to modeled curves using the Comsol multi-physics software coupled with a particle-swarm approach, allowing optimised Pz26 material parameters to be found (i.e. stiffness, coupling and permittivity matrices). The optimised Pz26 parameters are then used in an axi-symmetric Comsol model to make predictions about the DAEF power transfer, which is then experimentally confirmed. With an apparent input power of 1 VA and 4.2 MHz drive frequency, the measured power transfer efficiency across a 1.6 mm Al plate is ~34%. The effect of various system parameters on power transfer is explored, including bondline thickness and plate thickness. DAEF data communication is modelled using LTspice with three-port one-dimensional piezoelectric models, indicating that data rates of 115 kBit/s are feasible.

  13. DETECTING BARYON ACOUSTIC OSCILLATIONS

    SciTech Connect

    Labatie, A.; Starck, J. L.

    2012-02-20

    Baryon acoustic oscillations (BAOs) are a feature imprinted in the galaxy distribution by acoustic waves traveling in the plasma of the early universe. Their detection at the expected scale in large-scale structures strongly supports current cosmological models with a nearly linear evolution from redshift z Almost-Equal-To 1000 and the existence of dark energy. In addition, BAOs provide a standard ruler for studying cosmic expansion. In this paper, we focus on methods for BAO detection using the correlation function measurement {xi}-hat. For each method, we want to understand the tested hypothesis (the hypothesis H{sub 0} to be rejected) and the underlying assumptions. We first present wavelet methods which are mildly model-dependent and mostly sensitive to the BAO feature. Then we turn to fully model-dependent methods. We present the method used most often based on the {chi}{sup 2} statistic, but we find that it has limitations. In general the assumptions of the {chi}{sup 2} method are not verified, and it only gives a rough estimate of the significance. The estimate can become very wrong when considering more realistic hypotheses, where the covariance matrix of {xi}-hat depends on cosmological parameters. Instead, we propose to use the {Delta}l method based on two modifications: we modify the procedure for computing the significance and make it rigorous, and we modify the statistic to obtain better results in the case of varying covariance matrix. We verify with simulations that correct significances are different from the ones obtained using the classical {chi}{sup 2} procedure. We also test a simple example of varying covariance matrix. In this case we find that our modified statistic outperforms the classical {chi}{sup 2} statistic when both significances are correctly computed. Finally, we find that taking into account variations of the covariance matrix can change both BAO detection levels and cosmological parameter constraints.

  14. System for Multiplexing Acoustic Emission (AE) Instrumentation

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  15. Acoustic sensors using microstructures tunable with energy other than acoustic energy

    DOEpatents

    Datskos, Panagiotis G.

    2005-06-07

    A sensor for detecting acoustic energy includes a microstructure tuned to a predetermined acoustic frequency and a device for detecting movement of the microstructure. A display device is operatively linked to the movement detecting device. When acoustic energy strikes the acoustic sensor, acoustic energy having a predetermined frequency moves the microstructure, where the movement is detected by the movement detecting device.

  16. Acoustic sensors using microstructures tunable with energy other than acoustic energy

    DOEpatents

    Datskos, Panagiotis G.

    2003-11-25

    A sensor for detecting acoustic energy includes a microstructure tuned to a predetermined acoustic frequency and a device for detecting movement of the microstructure. A display device is operatively linked to the movement detecting device. When acoustic energy strikes the acoustic sensor, acoustic energy having a predetermined frequency moves the microstructure, where the movement is detected by the movement detecting device.

  17. Acoustic/Magnetic Stress Sensor

    NASA Technical Reports Server (NTRS)

    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. Acoustic trauma caused by lightning.

    PubMed

    Mora-Magaña, I; Collado-Corona, M A; Toral-Martiñòn, R; Cano, A

    1996-03-01

    Lesions produced by exposure to noise are frequent in everyday life. Injuries may be found in all systems of the human body, from the digestive to the endocrine, from the cardiovascular to the nervous system. Many organs may be damaged, the ear being one of them. It is known that noise produced by factories, airports, musical instruments and even toys can cause auditory loss. Noises in nature can also cause acoustic trauma. This report is the case history of acoustic trauma caused by lightning. The patient was studied with CAT scan, electroencephalogram, and brain mapping, impedance audiometry with tympanogram and acoustic reflex, audiometry and evoked otoacoustics emissions: distortion products and transients. PMID:8882110

  19. Recent Langley helicopter acoustics contributions

    NASA Technical Reports Server (NTRS)

    Morgan, Homer G.; Pao, S. P.; Powell, C. A.

    1988-01-01

    The helicopter acoustics program at NASA Langley has included technology for elements of noise control ranging from sources of noise to receivers of noise. The scope of Langley contributions for about the last decade is discussed. Specifically, the resolution of two certification noise quantification issues by subjective acoustics research, the development status of the helicopter system noise prediction program ROTONET are reviewed and the highlights from research on blade rotational, broadband, and blade vortex interaction noise sources are presented. Finally, research contributions on helicopter cabin (or interior) noise control are presented. A bibliography of publications from the Langley helicopter acoustics program for the past 10 years is included.

  20. In-Flow Acoustic Sensor

    NASA Technical Reports Server (NTRS)

    Allen, Christopher S. (Inventor)

    1995-01-01

    An acoustic sensor for measuring acoustic waves contained in fluid flow flowing over the sensor is introduced. The acoustic sensor reduces any unwanted self-noise associated with the flowing fluid by providing a nose cone having proper aerodynamic properties and by positioning the diaphragm of a microphone of the sensor at a location where any unwanted noise is at a relatively low level. The nose cone has a rounded, blunt or even sharp tip neither of which creates any major disturbances in the flowing fluid which it intercepts.

  1. Acoustic Microscope Inspection of Cylindrical Butt Laser Welds

    NASA Astrophysics Data System (ADS)

    Maev, R. Gr.; Severin, F.

    Presented work was made in order to develop the ultrasound technique for quality control of critical butt laser welds in automotive production. The set of powertrain assemblies was tested by high resolution acoustic microscopy method. The pulse-echo Tessonics AM 1102 scanning acoustic microscope was modified to accommodate cylindrical configuration of the parts. The spherically focused transducers with frequencies 15, 25 and 50 MHz were used; ultrasonic beam was focused on the joint area. Three-dimensional acoustic images were obtained and analyzed. The clear distinction between weld seam and remaining gap was demonstrated on the B- and C-scans representation. Seam depth varying from 0 up to 3.2 mm was measured along the weld. Different types of defects (porosity, cracks, lack of fusion) were detected and classified. The optimized analytical procedures for signal processing and advanced seam visualization were determined. The results were used as a basis for development of specialized instrumentation for inspection of this kind of parts in industrial environment. The technical requirements were established and the general design of new cylindrical acoustical scanner was made.

  2. Fourier plane imaging microscopy

    SciTech Connect

    Dominguez, Daniel Peralta, Luis Grave de; Alharbi, Nouf; Alhusain, Mdhaoui; Bernussi, Ayrton A.

    2014-09-14

    We show how the image of an unresolved photonic crystal can be reconstructed using a single Fourier plane (FP) image obtained with a second camera that was added to a traditional compound microscope. We discuss how Fourier plane imaging microscopy is an application of a remarkable property of the obtained FP images: they contain more information about the photonic crystals than the images recorded by the camera commonly placed at the real plane of the microscope. We argue that the experimental results support the hypothesis that surface waves, contributing to enhanced resolution abilities, were optically excited in the studied photonic crystals.

  3. Fast fluorescence holographic microscopy

    PubMed Central

    Qin, Wan; Yang, Xiaoqi; Li, Yingying; Peng, Xiang; Qu, Xinghua; Yao, Hai; Gao, Bruce Z.

    2015-01-01

    FINCHSCOPE is a new technology of fluorescence holographic microscopy. It has been successfully applied to recording high-resolution three-dimensional fluorescence images of biological specimens without the need for scanning. In this study, we revealed and analyzed an intrinsic phenomenon, called ghost lens effect, on spatial light modulator which is the core element enabling the incoherent correlation in the FINCHSCOPE. The ghost lens effect can degrade the imaging quality by introducing multiple spherical waves with different focal lengths into the correlation and thus increasing the noise in the recorded holograms. PMID:25767693

  4. High resolution MR microscopy

    NASA Astrophysics Data System (ADS)

    Ciobanu, Luisa

    Magnetic resonance imaging (MRI) microscopy [1] has the potential to bring the full capabilities of NMR to arbitrarily specified localized positions within small samples. The most interesting target of study is the living biological cell, with typical dimensions ˜100 mum, but with substructures that are much smaller, such as the cell nucleus (typically ˜10 mu m) and mitochondria (1--10 mum). One anticipates that the development of MR microscopy with resolution at the level of these substructures or better and with a wide, three dimensional field-of-view could open a new avenue of investigation into the biology of the living cell. Although the first MR image of a single biological cell was reported in 1987 [2], the cell imaged had quite large (˜1 mm diameter) spatial dimensions and the resolution obtained (on the order of 10 mu m) was not adequate for meaningful imaging of more typically sized cells. The quest for higher resolution has continued. In 1989 Zhou et al. [3] obtained fully three dimensional images with spatial resolution of (6.37 mum)3, or 260 femtoliters. While better "in-plane" resolutions (i.e., the resolution in 2 of the 3 spatial dimensions) have since been obtained, [4, 5] this volume resolution was not exceeded until quite recently by Lee et al., [6] who report 2D images having volume resolution of 75 mum 3 and in-plane resolution of 1 mum. In parallel with these advances in raw resolution several investigators [7, 8, 9] have focused on localized spectroscopy and/or chemical shift imaging. The key obstacles to overcome in MR microscopy are (1) the loss of signal to noise that occurs when observing small volumes and (2) molecular diffusion during the measurement or encoding. To date the problem of sensitivity has typically been addressed by employing small micro-coil receivers. [10] The problem of molecular diffusion can only be defeated with strong magnetic field gradients that can encode spatial information quickly. We report MR microscopy

  5. Scale Model Thruster Acoustic Measurement Results

    NASA Technical Reports Server (NTRS)

    Kenny, R. Jeremy; Vargas, Magda B.

    2013-01-01

    Subscale rocket acoustic data is used to predict acoustic environments for full scale rockets. Over the last several years acoustic data has been collected during horizontal tests of solid rocket motors. Space Launch System (SLS) Scale Model Acoustic Test (SMAT) was designed to evaluate the acoustics of the SLS vehicle including the liquid engines and solid rocket boosters. SMAT is comprised of liquid thrusters scalable to the Space Shuttle Main engines (SSME) and Rocket Assisted Take Off (RATO) motors scalable to the 5-segment Reusable Solid Rocket Motor (RSTMV). Horizontal testing of the liquid thrusters provided an opportunity to collect acoustic data from liquid thrusters to characterize the acoustic environments. Acoustic data was collected during the horizontal firings of a single thruster and a 4-thruster (Quad) configuration. Presentation scope. Discuss the results of the single and 4-thruster acoustic measurements. Compare the measured acoustic levels of the liquid thrusters to the Solid Rocket Test Motor V - Nozzle 2 (SRTMV-N2).

  6. Light Microscopy Module Imaging Tested and Demonstrated

    NASA Technical Reports Server (NTRS)

    Gati, Frank

    2004-01-01

    The Fluids Integrated Rack (FIR), a facility-class payload, and the Light Microscopy Module (LMM), a subrack payload, are integrated research facilities that will fly in the U.S. Laboratory module, Destiny, aboard the International Space Station. Both facilities are being engineered, designed, and developed at the NASA Glenn Research Center by Northrop Grumman Information Technology. The FIR is a modular, multiuser scientific research facility that is one of two racks that make up the Fluids and Combustion Facility (the other being the Combustion Integrated Rack). The FIR has a large volume dedicated for experimental hardware; easily reconfigurable diagnostics, power, and data systems that allow for unique experiment configurations; and customizable software. The FIR will also provide imagers, light sources, power management and control, command and data handling for facility and experiment hardware, and data processing and storage. The first payload in the FIR will be the LMM. The LMM integrated with the FIR is a remotely controllable, automated, on-orbit microscope subrack facility, with key diagnostic capabilities for meeting science requirements--including video microscopy to observe microscopic phenonema and dynamic interactions, interferometry to make thin-film measurements with nanometer resolution, laser tweezers to manipulate micrometer-sized particles, confocal microscopy to provide enhanced three-dimensional visualization of structures, and spectrophotometry to measure the photonic properties of materials. Vibration disturbances were identified early in the LMM development phase as a high risk for contaminating the science microgravity environment. An integrated FIR-LMM test was conducted in Glenn's Acoustics Test Laboratory to assess mechanical sources of vibration and their impact to microscopic imaging. The primary purpose of the test was to characterize the LMM response at the sample location, the x-y stage within the microscope, to vibration

  7. Effects of subsampling of passive acoustic recordings on acoustic metrics.

    PubMed

    Thomisch, Karolin; Boebel, Olaf; Zitterbart, Daniel P; Samaran, Flore; Van Parijs, Sofie; Van Opzeeland, Ilse

    2015-07-01

    Passive acoustic monitoring is an important tool in marine mammal studies. However, logistics and finances frequently constrain the number and servicing schedules of acoustic recorders, requiring a trade-off between deployment periods and sampling continuity, i.e., the implementation of a subsampling scheme. Optimizing such schemes to each project's specific research questions is desirable. This study investigates the impact of subsampling on the accuracy of two common metrics, acoustic presence and call rate, for different vocalization patterns (regimes) of baleen whales: (1) variable vocal activity, (2) vocalizations organized in song bouts, and (3) vocal activity with diel patterns. To this end, above metrics are compared for continuous and subsampled data subject to different sampling strategies, covering duty cycles between 50% and 2%. The results show that a reduction of the duty cycle impacts negatively on the accuracy of both acoustic presence and call rate estimates. For a given duty cycle, frequent short listening periods improve accuracy of daily acoustic presence estimates over few long listening periods. Overall, subsampling effects are most pronounced for low and/or temporally clustered vocal activity. These findings illustrate the importance of informed decisions when applying subsampling strategies to passive acoustic recordings or analyses for a given target species. PMID:26233026

  8. The effective acoustic environment of helicopter crewmen

    NASA Technical Reports Server (NTRS)

    Camp, R. T., Jr.; Mozo, B. T.

    1978-01-01

    Methods of measuring the composite acoustic environment of helicopters in order to quantify the effective acoustic environment of the crewmen and to assess the real acoustic hazards of the personnel are examined. It is indicated that the attenuation characteristics of the helmets and hearing protectors and the variables of the physiology of the human ear be accounted for in determining the effective acoustic environment of Army helicopter crewmen as well as the acoustic hazards of voice communications systems noise.

  9. Hybrid optical and acoustic force based sorting

    NASA Astrophysics Data System (ADS)

    O'Mahoney, Paul; Brodie, Graham W.; Wang, Han; Demore, Christine E. M.; Cochran, Sandy; Spalding, Gabriel C.; MacDonald, Michael P.

    2014-09-01

    We report the combined use of optical sorting and acoustic levitation to give particle sorting. Differing sizes of microparticles are sorted optically both with and without the aid of acoustic levitation, and the results compared to show that the use of acoustic trapping can increase sorting efficiency. The use of a transparent ultrasonic transducer is also shown to streamline the integration of optics and acoustics. We also demonstrate the balance of optical radiation pressure and acoustic levitation to achieve vertical sorting.

  10. Inducible fluorescent speckle microscopy

    PubMed Central

    Aguiar, Paulo; Belsley, Michael; Maiato, Helder

    2016-01-01

    The understanding of cytoskeleton dynamics has benefited from the capacity to generate fluorescent fiducial marks on cytoskeleton components. Here we show that light-induced imprinting of three-dimensional (3D) fluorescent speckles significantly improves speckle signal and contrast relative to classic (random) fluorescent speckle microscopy. We predict theoretically that speckle imprinting using photobleaching is optimal when the laser energy and fluorophore responsivity are related by the golden ratio. This relation, which we confirm experimentally, translates into a 40% remaining signal after speckle imprinting and provides a rule of thumb in selecting the laser power required to optimally prepare the sample for imaging. This inducible speckle imaging (ISI) technique allows 3D speckle microscopy to be performed in readily available libraries of cell lines or primary tissues expressing fluorescent proteins and does not preclude conventional imaging before speckle imaging. As a proof of concept, we use ISI to measure metaphase spindle microtubule poleward flux in primary cells and explore a scaling relation connecting microtubule flux to metaphase duration. PMID:26783303

  11. Inducible fluorescent speckle microscopy.

    PubMed

    Pereira, António J; Aguiar, Paulo; Belsley, Michael; Maiato, Helder

    2016-01-18

    The understanding of cytoskeleton dynamics has benefited from the capacity to generate fluorescent fiducial marks on cytoskeleton components. Here we show that light-induced imprinting of three-dimensional (3D) fluorescent speckles significantly improves speckle signal and contrast relative to classic (random) fluorescent speckle microscopy. We predict theoretically that speckle imprinting using photobleaching is optimal when the laser energy and fluorophore responsivity are related by the golden ratio. This relation, which we confirm experimentally, translates into a 40% remaining signal after speckle imprinting and provides a rule of thumb in selecting the laser power required to optimally prepare the sample for imaging. This inducible speckle imaging (ISI) technique allows 3D speckle microscopy to be performed in readily available libraries of cell lines or primary tissues expressing fluorescent proteins and does not preclude conventional imaging before speckle imaging. As a proof of concept, we use ISI to measure metaphase spindle microtubule poleward flux in primary cells and explore a scaling relation connecting microtubule flux to metaphase duration. PMID:26783303

  12. Magnetic force microscopy

    PubMed Central

    Passeri, Daniele; Dong, Chunhua; Reggente, Melania; Angeloni, Livia; Barteri, Mario; Scaramuzzo, Francesca A; De Angelis, Francesca; Marinelli, Fiorenzo; Antonelli, Flavia; Rinaldi, Federica; Marianecci, Carlotta; Carafa, Maria; Sorbo, Angela; Sordi, Daniela; Arends, Isabel WCE; Rossi, Marco

    2014-01-01

    Magnetic force microscopy (MFM) is an atomic force microscopy (AFM) based technique in which an AFM tip with a magnetic coating is used to probe local magnetic fields with the typical AFM spatial resolution, thus allowing one to acquire images reflecting the local magnetic properties of the samples at the nanoscale. Being a well established tool for the characterization of magnetic recording media, superconductors and magnetic nanomaterials, MFM is finding constantly increasing application in the study of magnetic properties of materials and systems of biological and biomedical interest. After reviewing these latter applications, three case studies are presented in which MFM is used to characterize: (i) magnetoferritin synthesized using apoferritin as molecular reactor; (ii) magnetic nanoparticles loaded niosomes to be used as nanocarriers for drug delivery; (iii) leukemic cells labeled using folic acid-coated core-shell superparamagnetic nanoparticles in order to exploit the presence of folate receptors on the cell membrane surface. In these examples, MFM data are quantitatively analyzed evidencing the limits of the simple analytical models currently used. Provided that suitable models are used to simulate the MFM response, MFM can be used to evaluate the magnetic momentum of the core of magnetoferritin, the iron entrapment efficiency in single vesicles, or the uptake of magnetic nanoparticles into cells. PMID:25050758

  13. Cameras for digital microscopy.

    PubMed

    Spring, Kenneth R

    2013-01-01

    This chapter reviews the fundamental characteristics of charge-coupled devices (CCDs) and related detectors, outlines the relevant parameters for their use in microscopy, and considers promising recent developments in the technology of detectors. Electronic imaging with a CCD involves three stages--interaction of a photon with the photosensitive surface, storage of the liberated charge, and readout or measurement of the stored charge. The most demanding applications in fluorescence microscopy may require as much as four orders of greater magnitude sensitivity. The image in the present-day light microscope is usually acquired with a CCD camera. The CCD is composed of a large matrix of photosensitive elements (often referred to as "pixels" shorthand for picture elements, which simultaneously capture an image over the entire detector surface. The light-intensity information for each pixel is stored as electronic charge and is converted to an analog voltage by a readout amplifier. This analog voltage is subsequently converted to a numerical value by a digitizer situated on the CCD chip, or very close to it. Several (three to six) amplifiers are required for each pixel, and to date, uniform images with a homogeneous background have been a problem because of the inherent difficulties of balancing the gain in all of the amplifiers. Complementary metal oxide semiconductor sensors also exhibit relatively high noise associated with the requisite high-speed switching. Both of these deficiencies are being addressed, and sensor performance is nearing that required for scientific imaging. PMID:23931507

  14. Correlative Stochastic Optical Reconstruction Microscopy and Electron Microscopy

    PubMed Central

    Kim, Doory; Deerinck, Thomas J.; Sigal, Yaron M.; Babcock, Hazen P.; Ellisman, Mark H.; Zhuang, Xiaowei

    2015-01-01

    Correlative fluorescence light microscopy and electron microscopy allows the imaging of spatial distributions of specific biomolecules in the context of cellular ultrastructure. Recent development of super-resolution fluorescence microscopy allows the location of molecules to be determined with nanometer-scale spatial resolution. However, correlative super-resolution fluorescence microscopy and electron microscopy (EM) still remains challenging because the optimal specimen preparation and imaging conditions for super-resolution fluorescence microscopy and EM are often not compatible. Here, we have developed several experiment protocols for correlative stochastic optical reconstruction microscopy (STORM) and EM methods, both for un-embedded samples by applying EM-specific sample preparations after STORM imaging and for embedded and sectioned samples by optimizing the fluorescence under EM fixation, staining and embedding conditions. We demonstrated these methods using a variety of cellular targets. PMID:25874453

  15. Acoustic agglomeration methods and apparatus

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B. (Inventor)

    1984-01-01

    Methods are described for using acoustic energy to agglomerate fine particles on the order of one micron diameter that are suspended in gas, to provide agglomerates large enough for efficient removal by other techniques. The gas with suspended particles, is passed through the length of a chamber while acoustic energy at a resonant chamber mode is applied to set up one or more acoustic standing wave patterns that vibrate the suspended particles to bring them together so they agglomerate. Several widely different frequencies can be applied to efficiently vibrate particles of widely differing sizes. The standing wave pattern can be applied along directions transversed to the flow of the gas. The particles can be made to move in circles by applying acoustic energy in perpendicular directions with the energy in both directions being of the same wavelength but 90 deg out of phase.

  16. Acoustic Characterization of Mesoscale Objects

    SciTech Connect

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

    2007-03-13

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

  17. PC and PVC Acoustics Demonstrations.

    ERIC Educational Resources Information Center

    Luzader, Stephen

    1990-01-01

    Described are four musical instruments constructed from polyvinyl chloride (PVC) pipe. The use of computerized synthesizers to play scales and chords is discussed. Suggestions for other illustrations of acoustics are included. (CW)

  18. Volumetric Imaging Using Acoustical Holography

    NASA Astrophysics Data System (ADS)

    Garlick, T. F.; Garlick, G. F.

    Transmission acoustical holography holds tremendous promise for medical imaging applications. As with optical holography, an image is obtained using the interference of two coherent acoustic sources, the transmitted object wave with a reference wave. Although resultant images are true holograms, depth can be difficult to quantify and an entire volume in one image can often result in "too much" information. Since Physicians/Radiologists are often interested in viewing a single plane at a time, techniques have been developed to generate acoustic holograms of "slices" within a volume. These primarily include focused transmission holography with spatial and frequency filtering techniques. These techniques along with an overview and current status of acoustical holography in medical imaging applications will be presented

  19. Study Acoustic Emissions from Composites

    NASA Technical Reports Server (NTRS)

    Walker, James; Workman,Gary

    1998-01-01

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

  20. Single mode acoustic fiber waveguide

    NASA Technical Reports Server (NTRS)

    Jackson, B. S.; May, R. G.; Claus, R. O.

    1984-01-01

    The single mode operation of a clad rod acoustic waveguide is described. Unlike conventional clad optical and acoustic waveguiding structures which use modes confined to a central core surrounded by a cladding, this guide supports neither core nor cladding modes but a single interface wave field on the core-cladding boundary. The propagation of this bound field and the potential improved freedom from spurious responses is discussed.

  1. Simplified Rotation In Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Gaspar, M. S.; Trinh, E. H.

    1989-01-01

    New technique based on old discovery used to control orientation of object levitated acoustically in axisymmetric chamber. Method does not require expensive equipment like additional acoustic drivers of precisely adjustable amplitude, phase, and frequency. Reflecting object acts as second source of sound. If reflecting object large enough, close enough to levitated object, or focuses reflected sound sufficiently, Rayleigh torque exerted on levitated object by reflected sound controls orientation of object.

  2. Stable And Oscillating Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin B.; Garrett, Steven L.

    1988-01-01

    Sample stability or instability determined by levitating frequency. Degree of oscillation of acoustically levitated object along axis of levitation chamber controlled by varying frequency of acoustic driver for axis above or below frequency of corresponding chamber resonance. Stabilization/oscillation technique applied in normal Earth gravity, or in absence of gravity to bring object quickly to rest at nominal levitation position or make object oscillate in desired range about that position.

  3. Acoustically-driven microfluidic systems

    SciTech Connect

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

    2000-06-23

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

  4. Acoustic techniques in nuclear safeguards

    SciTech Connect

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

    1995-07-01

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

  5. ACOUSTIC RECTIFICATION IN DISPERSIVE MEDIA

    SciTech Connect

    Cantrell, John H.

    2009-03-03

    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.

  6. Acoustics Research of Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Gao, Ximing; Houston, Janice D.

    2014-01-01

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

  7. Acoustic Rectification in Dispersive Media

    NASA Technical Reports Server (NTRS)

    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.

  8. Switchable and tunable film bulk acoustic resonator fabricated using barium strontium titanate active layer and Ta2O5/SiO2 acoustic reflector

    NASA Astrophysics Data System (ADS)

    Sbrockey, N. M.; Kalkur, T. S.; Mansour, A.; Khassaf, H.; Yu, H.; Aindow, M.; Alpay, S. P.; Tompa, G. S.

    2016-08-01

    A solidly mounted acoustic resonator was fabricated using a Ba0.60Sr0.40TiO3 (BST) film deposited by metal organic chemical vapor deposition. The device was acoustically isolated from the substrate using a Bragg reflector consisting of three pairs of Ta2O5/SiO2 layers deposited by chemical solution deposition. Transmission electron microscopy verified that the Bragg reflector was not affected by the high temperatures and oxidizing conditions necessary to process high quality BST films. Electrical characterization of the resonator demonstrated a quality factor (Q) of 320 and an electromechanical coupling coefficient (Kt2) of 7.0% at 11 V.

  9. Opto-acoustic cell permeation

    SciTech Connect

    Visuri, S R; Heredia, N

    2000-03-09

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

  10. Arctic acoustics ultrasonic modeling studies

    NASA Astrophysics Data System (ADS)

    Chamuel, Jacques R.

    1990-03-01

    A unique collection of laboratory ultrasonic modeling results are presented revealing and characterizing hidden pulsed seismoacoustic wave phenomena from 3-D range dependent liquid/solid boundaries. The research succeeded in isolating and identifying low frequency (10 to 500 Hz) transmission loss mechanisms and provided physical insight into Arctic acoustic problems generally beyond the state-of-the-art of theoretical and numerical analysis. The ultrasonic modeling studies dealt with controversial issues and existing discrepancies on seismo-acoustic waves at water/ice interface, sea ice thickness determination, low frequency transmission loss, and bottom leaky Rayleigh waves. The areas investigated include leaky Rayleigh waves at water/ice interface, leaky flexural waves in floating ice plates, effects of dry/wet cracks in sea ice on plate waves and near grazing acoustic waves, edge waves in floating plates, low frequency backscatter from ice keel width resonances, conversion of underwater acoustic waves into plate waves by keels, nondispersive flexural wave along apex of small angle solid wedge, Scholte and leaky Rayleigh waves along apex of immersed 90 ice wedge, backscatter from trailing edge of floes, floating plate resonances associated with near-grazing underwater acoustic waves, acoustic coupling between adjacent floes, and multiple bottom leaky Rayleigh wave components in water layer over solid bottom.

  11. Acoustics Research of Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Gao, Ximing; Houston, Janice

    2014-01-01

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

  12. Applications of subsurface microscopy.

    PubMed

    Tetard, Laurene; Passian, Ali; Farahi, Rubye H; Voy, Brynn H; Thundat, Thomas

    2012-01-01

    Exploring the interior of a cell is of tremendous importance in order to assess the effects of nanomaterials on biological systems. Outside of a controlled laboratory environment, nanomaterials will most likely not be conveniently labeled or tagged so that their translocation within a biological system cannot be easily identified and quantified. Ideally, the characterization of nanomaterials within a cell requires a nondestructive, label-free, and subsurface approach. Subsurface nanoscale imaging represents a real challenge for instrumentation. Indeed the tools available for high resolution characterization, including optical, electron or scanning probe microscopies, mainly provide topography images or require taggants that fluoresce. Although the intercellular environment holds a great deal of information, subsurface visualization remains a poorly explored area. Recently, it was discovered that by mechanically perturbing a sample, it was possible to observe its response in time with nanoscale resolution by probing the surface with a micro-resonator such as a microcantilever probe. Microcantilevers are used as the force-sensing probes in atomic force microscopy (AFM), where the nanometer-scale probe tip on the microcantilever interacts with the sample in a highly controlled manner to produce high-resolution raster-scanned information of the sample surface. Taking advantage of the existing capabilities of AFM, we present a novel technique, mode synthesizing atomic force microscopy (MSAFM), which has the ability to probe subsurface structures such as non-labeled nanoparticles embedded in a cell. In MSAFM mechanical actuators (PZTs) excite the probe and the sample at different frequencies as depicted in the first figure of this chapter. The nonlinear nature of the tip-sample interaction, at the point of contact of the probe and the surface of the sample, in the contact mode AFM configuration permits the mixing of the elastic waves. The new dynamic system comprises new

  13. Characterization of Polymer Blends: Optical Microscopy (*Polarized, Interference and Phase Contrast Microscopy*) and Confocal Microscopy

    SciTech Connect

    Ramanathan, Nathan Muruganathan; Darling, Seth B.

    2015-01-01

    Chapter 15 surveys the characterization of macro, micro and meso morphologies of polymer blends by optical microscopy. Confocal Microscopy offers the ability to view the three dimensional morphology of polymer blends, popular in characterization of biological systems. Confocal microscopy uses point illumination and a spatial pinhole to eliminate out-of focus light in samples that are thicker than the focal plane.

  14. Hyperspectral light sheet microscopy.

    PubMed

    Jahr, Wiebke; Schmid, Benjamin; Schmied, Christopher; Fahrbach, Florian O; Huisken, Jan

    2015-01-01

    To study the development and interactions of cells and tissues, multiple fluorescent markers need to be imaged efficiently in a single living organism. Instead of acquiring individual colours sequentially with filters, we created a platform based on line-scanning light sheet microscopy to record the entire spectrum for each pixel in a three-dimensional volume. We evaluated data sets with varying spectral sampling and determined the optimal channel width to be around 5 nm. With the help of these data sets, we show that our setup outperforms filter-based approaches with regard to image quality and discrimination of fluorophores. By spectral unmixing we resolved overlapping fluorophores with up to nanometre resolution and removed autofluorescence in zebrafish and fruit fly embryos. PMID:26329685

  15. Hyperspectral light sheet microscopy

    NASA Astrophysics Data System (ADS)

    Jahr, Wiebke; Schmid, Benjamin; Schmied, Christopher; Fahrbach, Florian O.; Huisken, Jan

    2015-09-01

    To study the development and interactions of cells and tissues, multiple fluorescent markers need to be imaged efficiently in a single living organism. Instead of acquiring individual colours sequentially with filters, we created a platform based on line-scanning light sheet microscopy to record the entire spectrum for each pixel in a three-dimensional volume. We evaluated data sets with varying spectral sampling and determined the optimal channel width to be around 5 nm. With the help of these data sets, we show that our setup outperforms filter-based approaches with regard to image quality and discrimination of fluorophores. By spectral unmixing we resolved overlapping fluorophores with up to nanometre resolution and removed autofluorescence in zebrafish and fruit fly embryos.

  16. Snapshot Hyperspectral Volumetric Microscopy.

    PubMed

    Wu, Jiamin; Xiong, Bo; Lin, Xing; He, Jijun; Suo, Jinli; Dai, Qionghai

    2016-01-01

    The comprehensive analysis of biological specimens brings about the demand for capturing the spatial, temporal and spectral dimensions of visual information together. However, such high-dimensional video acquisition faces major challenges in developing large data throughput and effective multiplexing techniques. Here, we report the snapshot hyperspectral volumetric microscopy that computationally reconstructs hyperspectral profiles for high-resolution volumes of ~1000 μm × 1000 μm × 500 μm at video rate by a novel four-dimensional (4D) deconvolution algorithm. We validated the proposed approach with both numerical simulations for quantitative evaluation and various real experimental results on the prototype system. Different applications such as biological component analysis in bright field and spectral unmixing of multiple fluorescence are demonstrated. The experiments on moving fluorescent beads and GFP labelled drosophila larvae indicate the great potential of our method for observing multiple fluorescent markers in dynamic specimens. PMID:27103155

  17. Snapshot Hyperspectral Volumetric Microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Jiamin; Xiong, Bo; Lin, Xing; He, Jijun; Suo, Jinli; Dai, Qionghai

    2016-04-01

    The comprehensive analysis of biological specimens brings about the demand for capturing the spatial, temporal and spectral dimensions of visual information together. However, such high-dimensional video acquisition faces major challenges in developing large data throughput and effective multiplexing techniques. Here, we report the snapshot hyperspectral volumetric microscopy that computationally reconstructs hyperspectral profiles for high-resolution volumes of ~1000 μm × 1000 μm × 500 μm at video rate by a novel four-dimensional (4D) deconvolution algorithm. We validated the proposed approach with both numerical simulations for quantitative evaluation and various real experimental results on the prototype system. Different applications such as biological component analysis in bright field and spectral unmixing of multiple fluorescence are demonstrated. The experiments on moving fluorescent beads and GFP labelled drosophila larvae indicate the great potential of our method for observing multiple fluorescent markers in dynamic specimens.

  18. Snapshot Hyperspectral Volumetric Microscopy

    PubMed Central

    Wu, Jiamin; Xiong, Bo; Lin, Xing; He, Jijun; Suo, Jinli; Dai, Qionghai

    2016-01-01

    The comprehensive analysis of biological specimens brings about the demand for capturing the spatial, temporal and spectral dimensions of visual information together. However, such high-dimensional video acquisition faces major challenges in developing large data throughput and effective multiplexing techniques. Here, we report the snapshot hyperspectral volumetric microscopy that computationally reconstructs hyperspectral profiles for high-resolution volumes of ~1000 μm × 1000 μm × 500 μm at video rate by a novel four-dimensional (4D) deconvolution algorithm. We validated the proposed approach with both numerical simulations for quantitative evaluation and various real experimental results on the prototype system. Different applications such as biological component analysis in bright field and spectral unmixing of multiple fluorescence are demonstrated. The experiments on moving fluorescent beads and GFP labelled drosophila larvae indicate the great potential of our method for observing multiple fluorescent markers in dynamic specimens. PMID:27103155

  19. Hyperspectral light sheet microscopy

    PubMed Central

    Jahr, Wiebke; Schmid, Benjamin; Schmied, Christopher; Fahrbach, Florian O.; Huisken, Jan

    2015-01-01

    To study the development and interactions of cells and tissues, multiple fluorescent markers need to be imaged efficiently in a single living organism. Instead of acquiring individual colours sequentially with filters, we created a platform based on line-scanning light sheet microscopy to record the entire spectrum for each pixel in a three-dimensional volume. We evaluated data sets with varying spectral sampling and determined the optimal channel width to be around 5 nm. With the help of these data sets, we show that our setup outperforms filter-based approaches with regard to image quality and discrimination of fluorophores. By spectral unmixing we resolved overlapping fluorophores with up to nanometre resolution and removed autofluorescence in zebrafish and fruit fly embryos. PMID:26329685

  20. Surface acoustic wave microfluidics

    PubMed Central

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

    2014-01-01

    The recent introduction of surface acoustic wave (SAW) technology onto lab-on-a-chip platforms has opened a new frontier in microfluidics. The advantages provided by such SAW microfluidics are numerous: simple fabrication, high biocompatibility, fast fluid actuation, versatility, compact and inexpensive devices and accessories, contact-free particle manipulation, and compatibility with other microfluidic components. We believe that these advantages enable SAW microfluidics to play a significant role in a variety of applications in biology, chemistry, engineering, and medicine. In this review article, we discuss the theory underpinning SAWs and their interactions with particles and the contacting fluids in which they are suspended. We then review the SAW-enabled microfluidic devices demonstrated to date, starting with devices that accomplish fluid mixing and transport through the use of travelling SAW; we follow that by reviewing the more recent innovations achieved with standing SAW that enable such actions as particle/cell focusing, sorting, and patterning. Finally, we look forward and appraise where the discipline of SAW microfluidics could go next. PMID:23900527

  1. Aquatic Acoustic Metrics Interface

    2012-12-18

    Fishes and marine mammals may suffer a range of potential effects from exposure to intense underwater sound generated by anthropogenic activities such as pile driving, shipping, sonars, and underwater blasting. Several underwater sound recording (USR) devices have been built to acquire samples of the underwater sound generated by anthropogenic activities. Software becomes indispensable for processing and analyzing the audio files recorded by these USRs. The new Aquatic Acoustic Metrics Interface Utility Software (AAMI) is specificallymore » designed for analysis of underwater sound recordings to provide data in metrics that facilitate evaluation of the potential impacts of the sound on aquatic animals. In addition to the basic functions, such as loading and editing audio files recorded by USRs and batch processing of sound files, the software utilizes recording system calibration data to compute important parameters in physical units. The software also facilitates comparison of the noise sound sample metrics with biological measures such as audiograms of the sensitivity of aquatic animals to the sound, integrating various components into a single analytical frame.« less

  2. Software for Acoustic Rendering

    NASA Technical Reports Server (NTRS)

    Miller, Joel D.

    2003-01-01

    SLAB is a software system that can be run on a personal computer to simulate an acoustic environment in real time. SLAB was developed to enable computational experimentation in which one can exert low-level control over a variety of signal-processing parameters, related to spatialization, for conducting psychoacoustic studies. Among the parameters that can be manipulated are the number and position of reflections, the fidelity (that is, the number of taps in finite-impulse-response filters), the system latency, and the update rate of the filters. Another goal in the development of SLAB was to provide an inexpensive means of dynamic synthesis of virtual audio over headphones, without need for special-purpose signal-processing hardware. SLAB has a modular, object-oriented design that affords the flexibility and extensibility needed to accommodate a variety of computational experiments and signal-flow structures. SLAB s spatial renderer has a fixed signal-flow architecture corresponding to a set of parallel signal paths from each source to a listener. This fixed architecture can be regarded as a compromise that optimizes efficiency at the expense of complete flexibility. Such a compromise is necessary, given the design goal of enabling computational psychoacoustic experimentation on inexpensive personal computers.

  3. Acoustics of the Intonarumori

    NASA Astrophysics Data System (ADS)

    Serafin, Stefania

    2005-04-01

    The Intonarumori were a family of musical instruments invented by the Italian futurist composer and painter Luigi Russolo. Each Intonarumori was made of a wooden parallelepiped sound box, inside which a wheel of different sizes and materials was setting into vibration a catgut or metal string. The pitch of the string was varied by using a lever, while the speed of the wheel was controlled by the performer using a crank. At one end of the string there was a drumhead that transmitted vibrations to the speaker. Unfortunately, all the original Intonarumori were destroyed after a fire during World War II. Since then, researchers have tried to understand the sound production mechanism of such instruments, especially by consulting the patents compiled by Russolo or by reading his book ``The art of noise.'' In this paper we describe the acoustics of the Intonarumori. Based on such description, we propose physical models that simulate such instruments. The intonarumori's string is modeled using a one dimensional waveguide, which is excited either by an impact or a friction model. The body of the instrument is modeled using a 3-D rectangular mesh, while the horn is considered as an omnidirectional radiator.

  4. Covert underwater acoustic communications.

    PubMed

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

    2010-11-01

    Low probability of detection (LPD) communications are conducted at a low received signal-to-noise ratio (SNR) to deter eavesdroppers to sense the presence of the transmitted signal. Successful detection at intended receiver heavily relies on the processing gain achieved by employing the direct-sequence spread-spectrum (DSSS) technique. For scenarios that lack a sufficiently low SNR to maintain LPD, another metric, referred to as low probability of interception (LPI), is of interest to protect the privacy of the transmitted information. If covert communications take place in underwater acoustic (UWA) environments, then additional challenges are present. The time-varying nature of the UWA channel prevents the employment of a long spreading waveform. Furthermore, UWA environments are frequency-selective channels with long memory, which imposes challenges to the design of the spreading waveform. In this paper, a covert UWA communication system that adopts the DSSS technique and a coherent RAKE receiver is investigated. Emphasis is placed on the design of a spreading waveform that not only accounts for the transceiver structure and frequency-selective nature of the UWA channel, but also possesses a superior LPI. The proposed techniques are evaluated using both simulated and SPACE'08 in-water experimental data. PMID:21110585

  5. Aquatic Acoustic Metrics Interface

    SciTech Connect

    2012-12-18

    Fishes and marine mammals may suffer a range of potential effects from exposure to intense underwater sound generated by anthropogenic activities such as pile driving, shipping, sonars, and underwater blasting. Several underwater sound recording (USR) devices have been built to acquire samples of the underwater sound generated by anthropogenic activities. Software becomes indispensable for processing and analyzing the audio files recorded by these USRs. The new Aquatic Acoustic Metrics Interface Utility Software (AAMI) is specifically designed for analysis of underwater sound recordings to provide data in metrics that facilitate evaluation of the potential impacts of the sound on aquatic animals. In addition to the basic functions, such as loading and editing audio files recorded by USRs and batch processing of sound files, the software utilizes recording system calibration data to compute important parameters in physical units. The software also facilitates comparison of the noise sound sample metrics with biological measures such as audiograms of the sensitivity of aquatic animals to the sound, integrating various components into a single analytical frame.

  6. Acoustic ground impedance meter

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.

    1981-01-01

    A compact, portable instrument was developed to measure the acoustic impedance of the ground, or other surfaces, by direct pressure-volume velocity measurement. A Helmholz resonator, constructed of heavy-walled stainless steel but open at the bottom, is positioned over the surface having the unknown impedance. The sound source, a cam-driven piston of known stroke and thus known volume velocity, is located in the neck of the resonator. The cam speed is a variable up to a maximum 3600 rpm. The sound pressure at the test surface is measured by means of a microphone flush-mounted in the wall of the chamber. An optical monitor of the piston displacement permits measurement of the phase angle between the volume velocity and the sound pressure, from which the real and imaginary parts of the impedance can be evaluated. Measurements using a 5-lobed cam can be made up to 300 Hz. Detailed design criteria and results on a soil sample are presented.

  7. Optimized multisectioned acoustic liners

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.

    1979-01-01

    A critical examination is presented of the use of optimized axially segmented acoustic liners to increase the attenuation of a liner. New calculations show that segmenting is most efficient at high frequencies with relatively long duct lengths where the attenuation is low for both uniform and segmented liners. Statistical considerations indicate little advantage in using optimized liners with more than two segments while the bandwidth of an optimized two-segment liner is shown to be nearly equal to that of a uniform liner. Multielement liner calculations show a large degradation in performance due to changes in assumed input modal structure. Finally, in order to substantiate previous and future analytical results, in-house (finite difference) and contractor (mode matching) programs are used to generate theoretical attenuations for a number of liner configurations for liners in a rectangular duct with no mean flow. Overall, the use of optimized multisectioned liners (sometimes called phased liners) fails to offer sufficient advantage over a uniform liner to warrant their use except in low frequency single mode application.

  8. Acoustically Enhanced Electroplating Being Developed

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C.

    2002-01-01

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

  9. Contour mode resonators with acoustic reflectors

    DOEpatents

    Olsson, Roy H.; Fleming, James G.; Tuck, Melanie R.

    2008-06-10

    A microelectromechanical (MEM) resonator is disclosed which has a linear or ring-shaped acoustic resonator suspended above a substrate by an acoustic reflector. The acoustic resonator can be formed with a piezoelectric material (e.g. aluminum nitride, zinc oxide or PZT), or using an electrostatically-actuated material. The acoustic reflector (also termed an acoustic mirror) uses alternating sections of a relatively low acoustic impedance Z.sub.L material and a relatively high acoustic impedance Z.sub.H material to isolate the acoustic resonator from the substrate. The MEM resonator, which can be formed on a silicon substrate with conventional CMOS circuitry, has applications for forming oscillators, rf filters, and acoustic sensors.

  10. Acoustical Characterization of the Columbia River Estuary

    NASA Astrophysics Data System (ADS)

    Reeder, D. B.

    2014-12-01

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

  11. Histopathology of the inner ear in unoperated acoustic neuroma.

    PubMed

    Mahmud, Mohd Ridzo; Khan, Aayesha M; Nadol, Joseph B

    2003-11-01

    Although hearing loss is the most common presenting symptom in patients with acoustic neuroma, the pathophysiology of hearing loss associated with acoustic neuroma is unknown. Although primary dysfunction of the auditory nerve is intuitively logical, available histopathologic and clinical data suggest that although neural degeneration is common, it alone does not adequately account for hearing loss in many cases. The purpose of this study was to evaluate 11 cases of unoperated unilateral acoustic neuromas. Temporal bones were identified by means of a search mechanism provided by the National Temporal Bone, Hearing, and Balance Pathology Resource Registry and were prepared for light microscopy by standard techniques. Quantification of spiral ganglion cells, hair cells, stria vascularis, and spiral ligament was accomplished for each specimen. In addition, the maximum diameter and volume of each tumor were calculated from histopathologic sections. Increasing tumor size did predict a reduced spiral ganglion count. However, although there was a tendency for decreasing spiral ganglion cell count and for increasing tumor size to predict a higher pure tone average and lower speech discrimination score, these correlations did not reach statistical significance. In tumor ears in which the speech discrimination score was 50% or less, there was always significant degeneration of other structures of the inner ear in addition to neurons, including hair cells, the stria vascularis, and the spiral ligament. Endolymphatic hydrops and eosinophilic precipitate in the perilymphatic spaces were found in 2 of 3 such cases. It is concluded that acoustic neuromas appear to cause hearing loss, not only by causing degeneration of the auditory nerve, but also by inducing degenerative changes in the inner ear. It is hypothesized that the proteinaceous material seen histologically may represent the products of up-regulated genes in acoustic neuroma, some of which may interfere with normal

  12. ACOUSTIC LINERS FOR TURBOFAN ENGINES

    NASA Technical Reports Server (NTRS)

    Minner, G. L.

    1994-01-01

    This program was developed to design acoustic liners for turbofan engines. This program combines results from theoretical models of wave alternation in acoustically treated passages with experimental data from full-scale fan noise suppressors. By including experimentally obtained information, the program accounts for real effects such as wall boundary layers, duct terminations, and sound modal structure. The program has its greatest use in generating a number of design specifications to be used for evaluation of trade-offs. The program combines theoretical and empirical data in designing annular acoustic liners. First an estimate of the noise output of the fan is made based on basic fan aerodynamic design variables. Then, using a target noise spectrum after alternation and the estimated fan noise spectrum, a design spectrum is calculated as their difference. Next, the design spectrum is combined with knowledge of acoustic liner performance and the liner design variables to specify the acoustic design. Details of the liner design are calculated by combining the required acoustic impedance with a mathematical model relating acoustic impedance to the physical structure of the liner. Input to the noise prediction part of the program consists of basic fan operating parameters, distance that the target spectrum is to be measured and the target spectrum. The liner design portion of the program requires the required alternation spectrum, desired values of length to height and several option selection parameters. Output from the noise prediction portion is a noise spectrum consisting of discrete tones and broadband noise. This may be used as input to the liner design portion of the program. The liner design portion of the program produces backing depths, open area ratios, and face plate thicknesses. This program is written in FORTRAN V and has been implemented in batch mode on a UNIVAC 1100 series computer with a central memory requirement of 12K (decimal) of 36 bit words.

  13. PORTABLE ACOUSTIC MONITORING PACKAGE (PAMP)

    SciTech Connect

    John l. Loth; Gary J. Morris; George M. Palmer; Richard Guiler; Deepak Mehra

    2003-07-01

    The 1st generation acoustic monitoring package was designed to detect and analyze weak acoustic signals inside natural gas transmission lines. Besides a microphone it housed a three-inch diameter aerodynamic acoustic signal amplifier to maximize sensitivity to leak induced {Delta}p type signals. The theory and test results of this aerodynamic signal amplifier was described in the master's degree thesis of our Research Assistant Deepak Mehra who is about to graduate. To house such a large three-inch diameter sensor required the use of a steel 300-psi rated 4 inch weld neck flange, which itself weighed already 29 pounds. The completed 1st generation Acoustic Monitoring Package weighed almost 100 pounds. This was too cumbersome to mount in the field, on an access port at a pipeline shut-off valve. Therefore a 2nd generation and truly Portable Acoustic Monitor was built. It incorporated a fully self-contained {Delta}p type signal sensor, rated for line pressures up to 1000 psi with a base weight of only 6 pounds. This is the Rosemont Inc. Model 3051CD-Range 0, software driven sensor, which is believed to have industries best total performance. Its most sensitive unit was purchased with a {Delta}p range from 0 to 3 inch water. This resulted in the herein described 2nd generation: Portable Acoustic Monitoring Package (PAMP) for pipelines up to 1000 psi. Its 32-pound total weight includes an 18-volt battery. Together with a 3 pound laptop with its 4-channel data acquisition card, completes the equipment needed for field acoustic monitoring of natural gas transmission pipelines.

  14. Acoustic communication in plant-animal interactions.

    PubMed

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

    2016-08-01

    Acoustic communication is widespread and well-studied in animals but has been neglected in other organisms such as plants. However, there is growing evidence for acoustic communication in plant-animal interactions. While knowledge about active acoustic signalling in plants (i.e. active sound production) is still in its infancy, research on passive acoustic signalling (i.e. reflection of animal sounds) revealed that bat-dependent plants have adapted to the bats' echolocation systems by providing acoustic reflectors to attract their animal partners. Understanding the proximate mechanisms and ultimate causes of acoustic communication will shed light on an underestimated dimension of information transfer between plants and animals. PMID:27423052

  15. Reflective echo tomographic imaging using acoustic beams

    DOEpatents

    Kisner, Roger; Santos-Villalobos, Hector J

    2014-11-25

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

  16. Acoustical sensing of cardiomyocyte cluster beating

    SciTech Connect

    Tymchenko, Nina; Kunze, Angelika; Dahlenborg, Kerstin; Svedhem, Sofia; Steel, Daniella

    2013-06-14

    Highlights: •An example of the application of QCM-D to live cell studies. •Detection of human pluripotent stem cell-derived cardiomyocyte cluster beating. •Clusters were studied in a thin liquid film and in a large liquid volume. •The QCM-D beating profile provides an individual fingerprint of the hPS-CMCs. -- Abstract: Spontaneously beating human pluripotent stem cell-derived cardiomyocytes clusters (CMCs) represent an excellent in vitro tool for studies of human cardiomyocyte function and for pharmacological cardiac safety assessment. Such testing typically requires highly trained operators, precision plating, or large cell quantities, and there is a demand for real-time, label-free monitoring of small cell quantities, especially rare cells and tissue-like structures. Array formats based on sensing of electrical or optical properties of cells are being developed and in use by the pharmaceutical industry. A potential alternative to these techniques is represented by the quartz crystal microbalance with dissipation monitoring (QCM-D) technique, which is an acoustic surface sensitive technique that measures changes in mass and viscoelastic properties close to the sensor surface (from nm to μm). There is an increasing number of studies where QCM-D has successfully been applied to monitor properties of cells and cellular processes. In the present study, we show that spontaneous beating of CMCs on QCM-D sensors can be clearly detected, both in the frequency and the dissipation signals. Beating rates in the range of 66–168 bpm for CMCs were detected and confirmed by simultaneous light microscopy. The QCM-D beating profile was found to provide individual fingerprints of the hPS-CMCs. The presented results point towards acoustical assays for evaluation cardiotoxicity.

  17. Mars Acoustic Anemometer

    NASA Astrophysics Data System (ADS)

    Banfield, D. J.

    2012-12-01

    We have developed a very high performance anemometer (wind gauge) for use at Mars. This instrument has great scientific as well as strategic reasons to be included on all future missions to the surface of Mars. We will discuss why we set out to develop this instrument, as well as why the previous wind sensors for Mars are insufficient to meet the scientific and strategic needs at Mars. We will also discuss how the instrument works, and how it differs from terrestrial counterparts. Additionally, we will discuss the current status of the instrument. Measuring winds at Mars is important to better understand the atmospheric circulation at Mars, as well as exchange between the surface and atmosphere. The main conduit of transport of water, and hence its current stability at any particular location on Mars is controlled by these atmospheric motions and the exchange between surface and atmosphere. Mars' large-scale winds are moderately well understood from orbital observations, but the interaction with the surface can only be addressed adequately in situ. Previous anemometers have been 2-D (with the exception of REMS on MSL) and slow response (typically <1Hz), and relatively low sensitivity/accuracy (>1 m/s). Our instrument is capable of fully 3-D measurements, with fast response (>20 Hz) and great sensitivity/accuracy (~3 cm/s). This significant step forward in performance is important for the surface-atmosphere exchanges of heat, momentum and volatiles. In particular, our instrument could directly measure the heat and momentum fluxes between surface and atmosphere using eddy-flux techniques proven terrestrially. When combined with a fast response volatile analysis instrument (e.g., a TLS) we can also measure eddy fluxes of volatile transport. Such a study would be nearly impossible to carry out with preceding anemometers sent to Mars with insufficient response time and sensitivity to adequately sample the turbulent eddies. Additionally, our instrument, using acoustics

  18. Virtual acoustic displays

    NASA Technical Reports Server (NTRS)

    Wenzel, Elizabeth M.

    1991-01-01

    A 3D auditory display can potentially enhance information transfer by combining directional and iconic information in a quite naturalistic representation of dynamic objects in the interface. Another aspect of auditory spatial clues is that, in conjunction with other modalities, it can act as a potentiator of information in the display. For example, visual and auditory cues together can reinforce the information content of the display and provide a greater sense of presence or realism in a manner not readily achievable by either modality alone. This phenomenon will be particularly useful in telepresence applications, such as advanced teleconferencing environments, shared electronic workspaces, and monitoring telerobotic activities in remote or hazardous situations. Thus, the combination of direct spatial cues with good principles of iconic design could provide an extremely powerful and information-rich display which is also quite easy to use. An alternative approach, recently developed at ARC, generates externalized, 3D sound cues over headphones in realtime using digital signal processing. Here, the synthesis technique involves the digital generation of stimuli using Head-Related Transfer Functions (HRTF's) measured in the two ear-canals of individual subjects. Other similar approaches include an analog system developed by Loomis, et. al., (1990) and digital systems which make use of transforms derived from normative mannikins and simulations of room acoustics. Such an interface also requires the careful psychophysical evaluation of listener's ability to accurately localize the virtual or synthetic sound sources. From an applied standpoint, measurement of each potential listener's HRTF's may not be possible in practice. For experienced listeners, localization performance was only slightly degraded compared to a subject's inherent ability. Alternatively, even inexperienced listeners may be able to adapt to a particular set of HRTF's as long as they provide adequate

  19. Sonification of acoustic emission data

    NASA Astrophysics Data System (ADS)

    Raith, Manuel; Große, Christian

    2014-05-01

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

  20. Acoustic constituents of prosodic typology

    NASA Astrophysics Data System (ADS)

    Komatsu, Masahiko

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

  1. In vivo sub-femtoliter resolution photoacoustic microscopy with higher frame rates

    NASA Astrophysics Data System (ADS)

    Lee, Szu-Yu; Lai, Yu-Hung; Huang, Kai-Chih; Cheng, Yu-Hsiang; Tseng, Tzu-Fang; Sun, Chi-Kuang

    2015-10-01

    Microscopy based on non-fluorescent absorption dye staining is widely used in various fields of biomedicine for 400 years. Unlike its fluorescent counterpart, non-fluorescent absorption microscopy lacks proper methodologies to realize its in vivo applications with a sub-femtoliter 3D resolution. Regardless of the most advanced high-resolution photoacoustic microscopy, sub-femtoliter spatial resolution is still unattainable, and the imaging speed is relatively slow. In this paper, based on the two-photon photoacoustic mechanism, we demonstrated a in vivo label free laser-scanning photoacoustic imaging modality featuring high frame rates and sub-femtoliter 3D resolution simultaneously, which stands as a perfect solution to 3D high resolution non-fluorescent absorption microscopy. Furthermore, we first demonstrated in vivo label-free two-photon acoustic microscopy on the observation of non-fluorescent melanin distribution within mouse skin.

  2. In vivo sub-femtoliter resolution photoacoustic microscopy with higher frame rates

    PubMed Central

    Lee, Szu-Yu; Lai, Yu-Hung; Huang, Kai-Chih; Cheng, Yu-Hsiang; Tseng, Tzu-Fang; Sun, Chi-Kuang

    2015-01-01

    Microscopy based on non-fluorescent absorption dye staining is widely used in various fields of biomedicine for 400 years. Unlike its fluorescent counterpart, non-fluorescent absorption microscopy lacks proper methodologies to realize its in vivo applications with a sub-femtoliter 3D resolution. Regardless of the most advanced high-resolution photoacoustic microscopy, sub-femtoliter spatial resolution is still unattainable, and the imaging speed is relatively slow. In this paper, based on the two-photon photoacoustic mechanism, we demonstrated a in vivo label free laser-scanning photoacoustic imaging modality featuring high frame rates and sub-femtoliter 3D resolution simultaneously, which stands as a perfect solution to 3D high resolution non-fluorescent absorption microscopy. Furthermore, we first demonstrated in vivo label-free two-photon acoustic microscopy on the observation of non-fluorescent melanin distribution within mouse skin. PMID:26487363

  3. Ultrafast scanning probe microscopy

    DOEpatents

    Weiss, Shimon; Chemla, Daniel S.; Ogletree, D. Frank; Botkin, David

    1995-01-01

    An ultrafast scanning probe microscopy method for achieving subpicosecond-temporal resolution and submicron-spatial resolution of an observation sample. In one embodiment of the present claimed invention, a single short optical pulse is generated and is split into first and second pulses. One of the pulses is delayed using variable time delay means. The first pulse is then directed at an observation sample located proximate to the probe of a scanning probe microscope. The scanning probe microscope produces probe-sample signals indicative of the response of the probe to characteristics of the sample. The second pulse is used to modulate the probe of the scanning probe microscope. The time delay between the first and second pulses is then varied. The probe-sample response signal is recorded at each of the various time delays created between the first and second pulses. The probe-sample response signal is then plotted as a function of time delay to produce a cross-correlation of the probe sample response. In so doing, the present invention provides simultaneous subpicosecond-temporal resolution and submicron-spatial resolution of the sample.

  4. NMR imaging microscopy

    SciTech Connect

    Not Available

    1986-10-01

    In the past several years, proton nuclear magnetic resonance (NMR) imaging has become an established technique in diagnostic medicine and biomedical research. Although much of the work in this field has been directed toward development of whole-body imagers, James Aguayo, Stephen Blackband, and Joseph Schoeninger of the Johns Hopkins University School of Medicine working with Markus Hintermann and Mark Mattingly of Bruker Medical Instruments, recently developed a small-bore NMR microscope with sufficient resolution to image a single African clawed toad cell (Nature 1986, 322, 190-91). This improved resolution should lead to increased use of NMR imaging for chemical, as well as biological or physiological, applications. The future of NMR microscopy, like that of many other newly emerging techniques, is ripe with possibilities. Because of its high cost, however, it is likely to remain primarily a research tool for some time. ''It's like having a camera,'' says Smith. ''You've got a way to look at things at very fine levels, and people are going to find lots of uses for it. But it is a very expensive technique - it costs $100,000 to add imaging capability once you have a high-resolution NMR, which itself is at least a $300,000 instrument. If it can answer even a few questions that can't be answered any other way, though, it may be well worth the cost.''

  5. Ultrafast scanning tunneling microscopy

    SciTech Connect

    Botkin, D.A. |

    1995-09-01

    I have developed an ultrafast scanning tunneling microscope (USTM) based on uniting stroboscopic methods of ultrafast optics and scanned probe microscopy to obtain nanometer spatial resolution and sub-picosecond temporal resolution. USTM increases the achievable time resolution of a STM by more than 6 orders of magnitude; this should enable exploration of mesoscopic and nanometer size systems on time scales corresponding to the period or decay of fundamental excitations. USTM consists of a photoconductive switch with subpicosecond response time in series with the tip of a STM. An optical pulse from a modelocked laser activates the switch to create a gate for the tunneling current, while a second laser pulse on the sample initiates a dynamic process which affects the tunneling current. By sending a large sequence of identical pulse pairs and measuring the average tunnel current as a function of the relative time delay between the pulses in each pair, one can map the time evolution of the surface process. USTM was used to measure the broadband response of the STM`s atomic size tunnel barrier in frequencies from tens to hundreds of GHz. The USTM signal amplitude decays linearly with the tunnel junction conductance, so the spatial resolution of the time-resolved signal is comparable to that of a conventional STM. Geometrical capacitance of the junction does not appear to play an important role in the measurement, but a capacitive effect intimately related to tunneling contributes to the measured signals and may limit the ultimate resolution of the USTM.

  6. Ultrafast scanning probe microscopy

    DOEpatents

    Weiss, S.; Chemla, D.S.; Ogletree, D.F.; Botkin, D.

    1995-05-16

    An ultrafast scanning probe microscopy method is described for achieving subpicosecond-temporal resolution and submicron-spatial resolution of an observation sample. In one embodiment of the present claimed invention, a single short optical pulse is generated and is split into first and second pulses. One of the pulses is delayed using variable time delay means. The first pulse is then directed at an observation sample located proximate to the probe of a scanning probe microscope. The scanning probe microscope produces probe-sample signals indicative of the response of the probe to characteristics of the sample. The second pulse is used to modulate the probe of the scanning probe microscope. The time delay between the first and second pulses is then varied. The probe-sample response signal is recorded at each of the various time delays created between the first and second pulses. The probe-sample response signal is then plotted as a function of time delay to produce a cross-correlation of the probe sample response. In so doing, the present invention provides simultaneous subpicosecond-temporal resolution and submicron-spatial resolution of the sample. 6 Figs.

  7. My 65 years in acoustics

    NASA Astrophysics Data System (ADS)

    Beranek, Leo L.

    2001-05-01

    My entry into acoustics began as research assistant to Professor F. V. Hunt at Harvard University. I received my doctorate in 1940 and directed the Electro-Acoustic Laboratory at Harvard from October 1940 until September 1945. In 1947, I became a tenured associate professor at MIT, and, with Richard H. Bolt, formed the consulting firm Bolt and Beranek, that later included Robert B. Newman, becoming BBN. My most significant contributions before 1970 were design of wedge-lined anechoic chambers, systemization of noise reduction in ventilation systems, design of the world's largest muffler for the testing of supersonic jet engines at NASA's Lewis Laboratory in Cleveland, speech interference level, NC noise criterion curves, heading New York Port Authority's noise study that resulted in mufflers on jet aircraft, and steep aircraft climb procedures, and publishing books titled, Acoustical Measurements, Acoustics, Noise Reduction, Noise and Vibration Control, and Music, Acoustics and Architecture. As President of BBN, I supervised the formation of the group that built and operated the ARPANET (1969), which, when split in two (using TCP/IP protocol) became the INTERNET (1984). Since then, I have written two books on Concert Halls and Opera Houses and have consulted on four concert halls and an opera house.

  8. Acoustic positioning and orientation prediction

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin B. (Inventor); Aveni, Glenn (Inventor); Putterman, Seth (Inventor); Rudnick, Joseph (Inventor)

    1990-01-01

    A method is described for use with an acoustic positioner, which enables a determination of the equilibrium position and orientation which an object assumes in a zero gravity environment, as well as restoring forces and torques of an object in an acoustic standing wave field. An acoustic standing wave field is established in the chamber, and the object is held at several different positions near the expected equilibrium position. While the object is held at each position, the center resonant frequency of the chamber is determined, by noting which frequency results in the greatest pressure of the acoustic field. The object position which results in the lowest center resonant frequency is the equilibrium position. The orientation of a nonspherical object is similarly determined, by holding the object in a plurality of different orientations at its equilibrium position, and noting the center resonant frequency for each orientation. The orientation which results in the lowest center resonant frequency is the equilibrium orientation. Where the acoustic frequency is constant, but the chamber length is variable, the equilibrium position or orientation is that which results in the greatest chamber length at the center resonant frequency.

  9. Deghosting in multipassive acoustic sensors

    NASA Astrophysics Data System (ADS)

    Yang, Rong; Ng, Gee Wah

    2004-04-01

    In this paper, we describe a deghosting algorithm in multiple passive acoustic sensor environment. In a passive acoustic sensor system, a target is detected by its bearing to the sensor, and the target location is obtained from triangulation of bearings on different sensors. However, in multi-passive sensor and multi-target scenario, triangulation is difficult. This is because multi-target triangulation results in a number of ghost targets being generated. In order to remove the triangulating ghosts, the deghosting technique is essential to distinguish the true targets from the ghost targets. We suggest a deghosting algorithm by applying Bayes" theorem and the likelihood function on the acoustic signals. A probability related to acoustic signal on each triangulating point is recursively computed and updated at every time stamp or frame. The triangulating point will be classified as a true target, once its probability exceeds a predefined threshold. Furthermore, acoustic signal has propagation delay. The situation yields the triangulating location biased to the bearing of the nearest sensor. In our algorithm, the propagation delay problem is solved by matching the histories of bearing tracks, and yields the unbiased location that has similar emitting times for the sensors contributing to the triangulation point. The emitting times can be derived from detecting times and propagation delays. Performance result is presented on simulation data.

  10. Acoustic correlates of vocal quality.

    PubMed

    Eskenazi, L; Childers, D G; Hicks, D M

    1990-06-01

    We have investigated the relationship between various voice qualities and several acoustic measures made from the vowel /i/ phonated by subjects with normal voices and patients with vocal disorders. Among the patients (pathological voices), five qualities were investigated: overall severity, hoarseness, breathiness, roughness, and vocal fry. Six acoustic measures were examined. With one exception, all measures were extracted from the residue signal obtained by inverse filtering the speech signal using the linear predictive coding (LPC) technique. A formal listening test was implemented to rate each pathological voice for each vocal quality. A formal listening test also rated overall excellence of the normal voices. A scale of 1-7 was used. Multiple linear regression analysis between the results of the listening test and the various acoustic measures was used with the prediction sums of squares (PRESS) as the selection criteria. Useful prediction equations of order two or less were obtained relating certain acoustic measures and the ratings of pathological voices for each of the five qualities. The two most useful parameters for predicting vocal quality were the Pitch Amplitude (PA) and the Harmonics-to-Noise Ratio (HNR). No acoustic measure could rank the normal voices. PMID:2359270

  11. [The effects of acoustic overstimulation].

    PubMed

    Häusler, R

    2004-01-01

    Basic aspects of acoustic trauma are presented. Exposure to loud noise leads to an acoustic traumatization with a temporary threshold shift initially and, with increasing exposure, intensity and duration, a permanent hearing loss. Impulse sound such as hammer blows on metal, gun shots and other detonations reaching peak levels of 160 to 180 dB is particularly hazardous to the inner ear. Playing loud musical instruments such as trumpets or percussion may also lead to hearing damage. Less dangerous than often believed is listening to electronically amplified music with walkmen, at discos or rock concerts. The reason is that, while the sound level is quite high, the particularly dangerous sound peaks are absent, as loudspeakers usually have an output limit of 110-120 dB. Traffic noise (cars, trains, air planes) is usually not threatening to the ear, but it may represent a considerable subjective annoyance and a stress factor leading to psychosomatic disturbances (neurovegetative symptoms, sleeping disorders). An effective treatment for the acoustic trauma is still missing. The systematic and consequent prophylaxis either with individual ear protectors (plugs or ear muffs) or by reducing the noise level at the source by means of isolation, encapsulation, or by using motors that are less noisy remains very important. Increasing awareness of acoustic pollution and preventive means have led to a reduction in the incidence of the acoustic trauma in the last decades. PMID:14997996

  12. Combined acoustic and optical trapping

    PubMed Central

    Thalhammer, G.; Steiger, R.; Meinschad, M.; Hill, M.; Bernet, S.; Ritsch-Marte, M.

    2011-01-01

    Combining several methods for contact free micro-manipulation of small particles such as cells or micro-organisms provides the advantages of each method in a single setup. Optical tweezers, which employ focused laser beams, offer very precise and selective handling of single particles. On the other hand, acoustic trapping with wavelengths of about 1 mm allows the simultaneous trapping of many, comparatively large particles. With conventional approaches it is difficult to fully employ the strengths of each method due to the different experimental requirements. Here we present the combined optical and acoustic trapping of motile micro-organisms in a microfluidic environment, utilizing optical macro-tweezers, which offer a large field of view and working distance of several millimeters and therefore match the typical range of acoustic trapping. We characterize the acoustic trapping forces with the help of optically trapped particles and present several applications of the combined optical and acoustic trapping, such as manipulation of large (75 μm) particles and active particle sorting. PMID:22025990

  13. Acoustic radiation from lined, unflanged ducts: Acoustic source distribution program

    NASA Technical Reports Server (NTRS)

    Beckemeyer, R. J.; Sawdy, D. T.

    1971-01-01

    An acoustic radiation analysis was developed to predict the far-field characteristics of fan noise radiated from an acoustically lined unflanged duct. This analysis is comprised of three modular digital computer programs which together provide a capability of accounting for the impedance mismatch at the duct exit plane. Admissible duct configurations include circular or annular, with or without an extended centerbody. This variation in duct configurations provides a capability of modeling inlet and fan duct noise radiation. The computer programs are described in detail.

  14. Photoacoustic microscopy based on polydimethylsiloxane thin film Fabry-Perot optical interferometer

    NASA Astrophysics Data System (ADS)

    Park, Soongho; Eom, Jonghyun; Shin, Jun Geun; Rim, Sunghwan; Lee, Byeong Ha

    2016-03-01

    We present a photoacoustic microscopy (PAM) system based on a Fabry-Perot Interferometer (FPI) consisting of a transparent Polydimethylsiloxane (PDMS) thin film. Most of the PAM systems have limitations with the system alignment because the ultrasound transducers for detection are not transparent. Therefore, the excitation laser source should avoid the opaque transducer to illuminate the sample, which makes the system difficult to build-up. Especially, the system volume is highly limited to be compact. In our experiment, to solve these difficulties, a FPI based on the PDMS film has been implemented and applied to measure the acoustic wave signal. The system uses a FPI as an acoustic wave detector instead of a conventional ultrasound transducer. A tunable laser was used to choose the quadrature-point at which the signal has the highly sensitve and linear response to the acoustic wave. Also a 20Hz pulsed Nd:YAG laser was used to generate acoustic waves from a sample. When the acoustic waves arrive at the PDMS film, one of the surfaces of the film is modulated at the detecting point, which gives the tuned FPI interference signal. From the signal arriving time, the depth location of the sample is calculated. As a primary experiment using the PDMS thin film as an ultrasound transducer, a couple of narrow black friction tapes located in a water container were used as the samples. This proposed imaging method can be used in various applications for the detection and measurement of acoustic waves.

  15. Two Papers on Classroom Acoustics. Good Classroom Acoustics Is a Good Investment. The Impact of Classroom Acoustics.

    ERIC Educational Resources Information Center

    Lubman, David; Sutherland, Louis C.

    This document consists of two papers. The first, titled "Good Classroom Acoustics Is a Good Investment," identifies and estimates some of the costs for good acoustics in new school construction. It also identifies and estimates some previously unrecognized economic benefits of good acoustics, as well as some of the hidden costs of marginal or poor…

  16. Acoustic metamaterials for sound mitigation

    NASA Astrophysics Data System (ADS)

    Assouar, Badreddine; Oudich, Mourad; Zhou, Xiaoming

    2016-05-01

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

  17. Classroom acoustics: Three pilot studies

    NASA Astrophysics Data System (ADS)

    Smaldino, Joseph J.

    2005-04-01

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

  18. Acoustics of a broadcast center

    NASA Astrophysics Data System (ADS)

    Beristain, Sergio

    2003-04-01

    A broadcast system in Mexico City had to change facilities in order to concentrate in a single site all related broadcast stations and production studios in order to facilitate its normal operation. This led to a design which included the acoustic noise isolation and the interior acoustics of every studio and control room, together with the audio interconection, the electricity layout, the air conditioning system, the office building, etc. This paper presents the acoustics profile of the center, including final results of the construction as they were measured on completion of the installation. The complex has seven AM and FM broadcast stations, plus seven production studios for news, commercials and radio-novels plus an audio master control room, and everything was completed within four months.

  19. Acoustic Localization with Infrasonic Signals

    NASA Astrophysics Data System (ADS)

    Threatt, Arnesha; Elbing, Brian

    2015-11-01

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

  20. Acoustic metasurface with hybrid resonances.

    PubMed

    Ma, Guancong; Yang, Min; Xiao, Songwen; Yang, Zhiyu; Sheng, Ping

    2014-09-01

    An impedance-matched surface has the property that an incident wave generates no reflection. Here we demonstrate that by using a simple construction, an acoustically reflecting surface can acquire hybrid resonances and becomes impedance-matched to airborne sound at tunable frequencies, such that no reflection is generated. Each resonant cell of the metasurface is deep-subwavelength in all its spatial dimensions, with its thickness less than the peak absorption wavelength by two orders of magnitude. As there can be no transmission, the impedance-matched acoustic wave is hence either completely absorbed at one or multiple frequencies, or converted into other form(s) of energy, such as an electrical current. A high acoustic-electrical energy conversion efficiency of 23% is achieved. PMID:24880731

  1. Coherent acoustic phonons in nanostructures

    NASA Astrophysics Data System (ADS)

    Dekorsy, T.; Taubert, R.; Hudert, F.; Bartels, A.; Habenicht, A.; Merkt, F.; Leiderer, P.; Köhler, K.; Schmitz, J.; Wagner, J.

    2008-02-01

    Phonons are considered as a most important origin of scattering and dissipation for electronic coherence in nanostructures. The generation of coherent acoustic phonons with femtosecond laser pulses opens the possibility to control phonon dynamics in amplitude and phase. We demonstrate a new experimental technique based on two synchronized femtosecond lasers with GHz repetition rate to study the dynamics of coherently generated acoustic phonons in semiconductor heterostructures with high sensitivity. High-speed synchronous optical sampling (ASOPS) enables to scan a time-delay of 1 ns with 100 fs time resolution with a frequency in the kHz range without a moving part in the set-up. We investigate the dynamics of coherent zone-folded acoustic phonons in semiconductor superlattices (GaAs/AlAs and GaSb/InAs) and of coherent vibration of metallic nanostructures of non-spherical shape using ASOPS.

  2. Adaptive scanning probe microscopies

    SciTech Connect

    Swartzentruber, B.S.; Bouchard, A.M.; Osbourn, G.C.

    1997-02-01

    This work is comprised of two major sections. In the first section the authors develop multivariate image classification techniques to distinguish and identify surface electronic species directly from multiple-bias scanning tunneling microscope (STM) images. Multiple measurements at each site are used to distinguish and categorize inequivalent electronic or atomic species on the surface via a computerized classification algorithm. Then, comparison with theory or other suitably chosen experimental data enables the identification of each class. They demonstrate the technique by analyzing dual-polarity constant-current topographs of the Ge(111) surface. Just two measurements, negative- and positive-bias topography height, permit pixels to be separated into seven different classes. Labeling four of the classes as adatoms, first-layer atoms, and two inequivalent rest-atom sites, they find excellent agreement with the c(2 x 8) structure. The remaining classes are associated with structural defects and contaminants. This work represents a first step toward developing a general electronic/chemical classification and identification tool for multivariate scanning probe microscopy imagery. In the second section they report measurements of the diffusion of Si dimers on the Si(001) surface at temperatures between room temperature and 128 C using a novel atom-tracking technique that can resolve every diffusion event. The atom tracker employs lateral-positioning feedback to lock the STM probe tip into position above selected atoms with sub-Angstrom precision. Once locked the STM tracks the position of the atoms as they migrate over the crystal surface. By tracking individual atoms directly, the ability of the instrument to measure dynamic events is increased by a factor of {approximately} 1,000 over conventional STM imaging techniques.

  3. Epi-Fluorescence Microscopy

    PubMed Central

    Webb, Donna J.; Brown, Claire M.

    2012-01-01

    Epi-fluorescence microscopy is available in most life sciences research laboratories, and when optimized can be a central laboratory tool. In this chapter, the epi-fluorescence light path is introduced and the various components are discussed in detail. Recommendations are made for incident lamp light sources, excitation and emission filters, dichroic mirrors, objective lenses, and charge-coupled device (CCD) cameras in order to obtain the most sensitive epi-fluorescence microscope. The even illumination of metal-halide lamps combined with new “hard” coated filters and mirrors, a high resolution monochrome CCD camera, and a high NA objective lens are all recommended for high resolution and high sensitivity fluorescence imaging. Recommendations are also made for multicolor imaging with the use of monochrome cameras, motorized filter turrets, individual filter cubes, and corresponding dyes that are the best choice for sensitive, high resolution multicolor imaging. Images should be collected using Nyquist sampling and should be corrected for background intensity contributions and nonuniform illumination across the field of view. Photostable fluorescent probes and proteins that absorb a lot of light (i.e., high extinction co-efficients) and generate a lot of fluorescence signal (i.e., high quantum yields) are optimal. A neuronal immune-fluorescence labeling protocol is also presented. Finally, in order to maximize the utility of sensitive wide-field microscopes and generate the highest resolution images with high signal-to-noise, advice for combining wide-field epi-fluorescence imaging with restorative image deconvolution is presented. PMID:23026996

  4. Acoustic data transmission through a drill string

    DOEpatents

    Drumheller, D.S.

    1988-04-21

    Acoustical signals are transmitted through a drill string by canceling upward moving acoustical noise and by preconditioning the data in recognition of the comb filter impedance characteristics of the drill string. 5 figs.

  5. Vestibular Schwannoma (Acoustic Neuroma) and Neurofibromatosis

    MedlinePlus

    ... Home » Health Info » Hearing, Ear Infections, and Deafness Vestibular Schwannoma (Acoustic Neuroma) and Neurofibromatosis On this page: ... more information about vestibular schwannomas? What is a vestibular schwannoma (acoustic neuroma)? Inner ear with vestibular schwannoma ( ...

  6. On the Synchronization of Acoustic Gravity Waves

    NASA Astrophysics Data System (ADS)

    Lonngren, Karl E.; Bai, Er-Wei

    Using the model proposed by Stenflo, we demonstrate that acoustic gravity waves found in one region of space can be synchronized with acoustic gravity waves found in another region of space using techniques from modern control theory.

  7. Acoustic network event classification using swarm optimization

    NASA Astrophysics Data System (ADS)

    Burman, Jerry

    2013-05-01

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

  8. Acoustics of a Nonhomogeneous Moving Medium.

    NASA Technical Reports Server (NTRS)

    Blokhintsev, D I

    1956-01-01

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

  9. Acoustic Trauma - Hearing Loss in Teenagers

    MedlinePlus

    ... Issues Listen Español Text Size Email Print Share Acoustic Trauma - Hearing Loss in Teenagers Page Content Article ... temporary or permanent hearing loss. This is called acoustic trauma. How loud is 85 decibels? Surprisingly, not ...

  10. Acoustic behaviors of unsaturated soils

    NASA Astrophysics Data System (ADS)

    Lu, Z.

    2011-12-01

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

  11. Acoustically-Induced Electrical Signals

    NASA Astrophysics Data System (ADS)

    Brown, S. R.

    2014-12-01

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

  12. Acoustic emission linear pulse holography

    DOEpatents

    Collins, H. Dale; Busse, Lawrence J.; Lemon, Douglas K.

    1985-01-01

    Defects in a structure are imaged as they propagate, using their emitted acoustic energy as a monitored source. Short bursts of acoustic energy propagate through the structure to a discrete element receiver array. A reference timing transducer located between the array and the inspection zone initiates a series of time-of-flight measurements. A resulting series of time-of-flight measurements are then treated as aperture data and are transferred to a computer for reconstruction of a synthetic linear holographic image. The images can be displayed and stored as a record of defect growth.

  13. Gas sensing with acoustic devices

    SciTech Connect

    Martin, S.J.; Frye, G.C.; Spates, J.J.; Butler, M.A.

    1996-12-31

    A survey is made of acoustic devices that are suitable as gas and vapor sensors. This survey focuses on attributes such as operating frequency, mass sensitivity, quality factor (Q), and their ability to be fabricated on a semiconductor substrate to allow integration with electronic circuitry. The treatment of the device surface with chemically-sensitive films to detect species of interest is discussed. Strategies for improving discrimination are described, including sensor arrays and species concentration and separation schemes. The advantages and disadvantages of integrating sensors with microelectronics are considered, along with the effect on sensitivity of scaling acoustic gas sensors to smaller size.

  14. Acoustic emission linear pulse holography

    SciTech Connect

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

    1985-07-30

    Defects in a structure are imaged as they propagate, using their emitted acoustic energy as a monitored source. Short bursts of acoustic energy propagate through the structure to a discrete element receiver array. A reference timing transducer located between the array and the inspection zone initiates a series of time-of-flight measurements. A resulting series of time-of-flight measurements are then treated as aperture data and are transferred to a computer for reconstruction of a synthetic linear holographic image. The images can be displayed and stored as a record of defect growth.

  15. Particle analysis in an acoustic cytometer

    DOEpatents

    Kaduchak, Gregory; Ward, Michael D

    2012-09-18

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

  16. Polariton Condensation in Dynamic Acoustic Lattices

    NASA Astrophysics Data System (ADS)

    Cerda-Méndez, E. A.; Krizhanovskii, D. N.; Wouters, M.; Bradley, R.; Biermann, K.; Guda, K.; Hey, R.; Santos, P. V.; Sarkar, D.; Skolnick, M. S.

    2010-09-01

    We demonstrate that the tunable potential introduced by a surface acoustic wave on a homogeneous polariton condensate leads to fragmentation of the condensate into an array of wires which move with the acoustic velocity. Reduction of the spatial coherence of the condensate emission along the surface acoustic wave direction is attributed to the suppression of coupling between the spatially modulated condensates. Interparticle interactions observed at high polariton densities screen the acoustic potential, partially reversing its effect on spatial coherence.

  17. Computational ocean acoustics: Advances in 3D ocean acoustic modeling

    NASA Astrophysics Data System (ADS)

    Schmidt, Henrik; Jensen, Finn B.

    2012-11-01

    The numerical model of ocean acoustic propagation developed in the 1980's are still in widespread use today, and the field of computational ocean acoustics is often considered a mature field. However, the explosive increase in computational power available to the community has created opportunities for modeling phenomena that earlier were beyond reach. Most notably, three-dimensional propagation and scattering problems have been prohibitive computationally, but are now addressed routinely using brute force numerical approaches such as the Finite Element Method, in particular for target scattering problems, where they are being combined with the traditional wave theory propagation models in hybrid modeling frameworks. Also, recent years has seen the development of hybrid approaches coupling oceanographic circulation models with acoustic propagation models, enabling the forecasting of sonar performance uncertainty in dynamic ocean environments. These and other advances made over the last couple of decades support the notion that the field of computational ocean acoustics is far from being mature. [Work supported by the Office of Naval Research, Code 321OA].

  18. On the Inverse Problems of Nonlinear Acoustics and Acoustic Turbulence

    NASA Astrophysics Data System (ADS)

    Gurbatov, S. N.; Rudenko, O. V.

    2015-12-01

    We consider the problem of retrieval of the radiated acoustic signal parameters from the measured wave field in some cross section of the nonlinear medium. The possibilities of solving regular and statistical inverse problems are discussed on the basis of the solution of the Burgers equation for zero and infinitesimal viscosities.

  19. Calculating room acoustic parameters from pseudo-impulsive acoustic sources

    NASA Astrophysics Data System (ADS)

    San Martin, Maria L.; Vela, Antonio; San Martin, Ricardo; Arana, Miguel A.

    2002-11-01

    The impulse response function provides complete information to predict the acoustic response of a room to an acoustic input of arbitrary characteristics. At this job study, small explosions of firecrackers are proposed to be used as pseudo-impulsive acoustics sources to determine some acoustic parameters of a room such as reverberation time, definition, and clarity, comparing these results to those obtained with other techniques. A previous characterization of these sources allows us to state that they can be used for this purpose because they are, in practice, omnidirectional, their temporary pattern is highly repetitive and their spectral power is, as well, repetitive and with enough power in octave bands from 125 Hz to 8 kHz. If the linear time-invariant system impulse response h(t) is known, output signal s(t) regarding any arbitrary signal s(t) can be obtained. For our pseudo-impulsive sources, the output signal s(t) has been taken as impulse response h(t). Using the integrated impulse response method suggested by Schroeder, it has been stated that both the mean values and standard deviations for some parameters are practically identical to results obtained with other usual techniques. (To be presented in Spanish.)

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  1. Electronic Blending in Virtual Microscopy

    ERIC Educational Resources Information Center

    Maybury, Terrence S.; Farah, Camile S.

    2010-01-01

    Virtual microscopy (VM) is a relatively new technology that transforms the computer into a microscope. In essence, VM allows for the scanning and transfer of glass slides from light microscopy technology to the digital environment of the computer. This transition is also a function of the change from print knowledge to electronic knowledge, or as…

  2. Classroom Acoustics: Understanding Barriers to Learning.

    ERIC Educational Resources Information Center

    Crandell, Carl C., Ed.; Smaldino, Joseph J., Ed.

    2001-01-01

    This booklet explores classroom acoustics and their importance on the learning potential of children with hearing loss and related disabilities. The booklet also reviews research on classroom acoustics and the need for the development of classroom acoustics standards. Chapters examine: 1) a speech-perception model demonstrating the linkage between…

  3. Acoustically swept rotor. [helicopter noise reduction

    NASA Technical Reports Server (NTRS)

    Schmitz, F. H.; Boxwell, D. A.; Vause, R. (Inventor)

    1979-01-01

    Impulsive noise reduction is provided in a rotor blade by acoustically sweeping the chord line from root to tip so that the acoustic radiation resulting from the summation of potential singularities used to model the flow about the blade tend to cancel for all times at an observation point in the acoustic far field.

  4. The Acoustical Apparatus of Rudolph Koenig.

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    1992-01-01

    Discusses the history of Rudolph Koenig's contribution to the development of acoustical apparatus. Contributions include the clock fork to determine absolute acoustic frequencies, a forerunner of the oscilloscope called the manometric flame, and an acoustic interference apparatus used in the Fourier synthesis of musical sounds. (MDH)

  5. Multi-reflective acoustic wave device

    DOEpatents

    Andle, Jeffrey C.

    2006-02-21

    An acoustic wave device, which utilizes multiple localized reflections of acoustic wave for achieving an infinite impulse response while maintaining high tolerance for dampening effects, is disclosed. The device utilized a plurality of electromechanically significant electrodes disposed on most of the active surface. A plurality of sensors utilizing the disclosed acoustic wave mode device are also described.

  6. Multi-contrast Photoacoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Yao, Junjie

    Photoacoustic microscopy is a hybrid imaging modality with high spatial resolution, moderate imaging depth, excellent imaging contrast and functional imaging capability. Taking full advantage of this powerful weapon, we have investigated different anatomical, functional, flow dynamic and metabolic parameter measurements using photoacoustic microscopy. Specifically, Evans-blue dye was used to enhance photoacoustic microscopy of capillaries; label-free transverse and axial blood flow was measured based on bandwidth broadening and time shift of the photoacoustic signals; metabolic rate of oxygen was quantified in vivo from all the five parameters measured by photoacoustic microcopy; whole cross-sectional imaging of small intestine was achieved on a double-illumination photoacoustic microscopy with extended depth of focus and imaging depth; hemodynamic imaging was performed on a MEMS-mirror enhanced photoacoustic microscopy with a cross-sectional imaging rate of 400 Hz. As a maturing imaging technique, PAM is expected to find new applications in both fundamental life science and clinical practice.

  7. Reverberant Acoustic Testing and Direct Field Acoustic Testing Acoustic Standing Waves and their Impact on Structural Responses

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    The aerospace industry has been using two methods of acoustic testing to qualify flight hardware: (1) Reverberant Acoustic Test (RAT), (2) Direct Field Acoustic Test (DFAT). The acoustic field obtained by RAT is generally understood and assumed to be diffuse, expect below Schroeder cut-of frequencies. DFAT method of testing has some distinct advantages over RAT, however the acoustic field characteristics can be strongly affected by test setup such as the speaker layouts, number and location of control microphones and control schemes. In this paper the following are discussed based on DEMO tests performed at APL and JPL: (1) Acoustic wave interference patterns and acoustic standing waves, (2) The structural responses in RAT and DFAT.

  8. Acoustical Measurement Of Furnace Temperatures

    NASA Technical Reports Server (NTRS)

    Parthasarathy, Shakkottai; Venkateshan, Shakkottai P.

    1989-01-01

    Simple probes withstand severe conditions, yet give spatially-resolved temperature readings. Prototype acoustical system developed to measure temperatures from ambient to 1,800 degree F in such structures as large industrial lime kilns and recovery-boiler furnaces. Pulses of sound reflected from obstructions in sensing tube. Speed of sound and temperature in each segment deduced from travel times of pulses.

  9. Acoustically-tuned optical spectrometer

    NASA Technical Reports Server (NTRS)

    Sklar, E.

    1981-01-01

    Lens arrangement corrects for aberrations and gives resolution of 0.7 seconds of arc. In spectrometer, light from telescope is relayed by doublet lens to acoustically tuned optical filter. Selected wavelengths are relayed by triplet lens to charge coupled device camera. Intervening cylindrical lens, tilted at 12 degree angle, corrects for astigmatism and coma introduced by two element birefringent crystal in filter.

  10. Does acoustic testing strand whales?

    NASA Astrophysics Data System (ADS)

    Frantzis, A.

    1998-03-01

    Mass strandings of live whales have been explained by proposing many `natural' or human-related causes. I found that a recent stranding of Cuvier's beaked whale coincided closely in time and location with military tests of an acoustic system for submarine detection being carried out by the North Atlantic Treaty Organization (NATO).

  11. Joint Acoustic Propagation Experiment (JAPE)

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  12. Acoustics in the Martian Atmosphere

    NASA Astrophysics Data System (ADS)

    Williams, J.-P.

    2000-10-01

    With the advent of the first attempt to deliver an acoustic microphone to the Martian surface aboard the failed Mars Polar Lander, there has been growing interests in the development of acoustic sensors to compliment scientific payloads on future spacecraft. Terrestrial scientist have been very successful in using infrasound (sound at frequencies below human detection, < 20 Hz) to detect and monitor atmospheric phenomena related to weather, tornadoes, mountain waves, microbaroms, ionospheric and auroral disturbances, and meteror/fireballs, as well as anthropogenic sources such as aircraft and nuclear explosions. Sounds on Mars at the audible frequencies (20 Hz to 20 kHz) will be severely attenuated due to viscous relaxation and thermal diffusion (collectively referred to as classical attenuation) which will be much more severe in the colder, less dense Martian atmosphere. Molecular relaxation of carbon dioxide will also contribute to the sound absorption in the lower audible frequencies. Since classical attenuation increases as a function of the frequency squared, at low infrasonic frequencies ( < 10 Hz), classical attenuation becomes less significant and sound absorption in the Martian atmosphere becomes more similar to that of the terrestrial atmosphere for the same frequencies. At these longer wavelengths, geometric spreading will dominate as the source of attenuation as the acoustic energy is spread out over an ever increasing spherical wave front. This implies that infrasound (10 to 0.01 Hz) will be a useful frequency range for future acoustic sensors developed for scientific payloads delivered to the Martian surface.

  13. Acoustic counter-sniper system

    NASA Astrophysics Data System (ADS)

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

    1997-02-01

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

  14. Acoustic optic hybrid (AOH) sensor

    PubMed

    Matthews; Arrieta

    2000-09-01

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

  15. Acoustic Absorption Characteristics of People.

    ERIC Educational Resources Information Center

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

    1968-01-01

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

  16. SES and Acoustics at GSFC

    NASA Technical Reports Server (NTRS)

    Hogue, Patrick

    2008-01-01

    This paper presents air and surface cleanliness characterization of the acoustics test facility and large (SES) thermal vacuum chamber at Goddard Space flight Center in Greenbelt, MD during the New Horizons Pluto probe program. It is shown that slow back-fill of the SES chamber is necessary to prevent excessive particle redistribution.

  17. Acoustical Modifications for the Classroom.

    ERIC Educational Resources Information Center

    Crandell, Carl C.; Smaldino, Joseph J.

    1999-01-01

    This article reviews procedures for evaluating, measuring, and modifying noise and reverberation levels in the classroom environment. Recommendations include: relocating children away from high noise sources, such as fans, air conditioners, heating ducts, and faulty lighting fixtures, using sound-absorbing materials, using acoustical ceiling tile…

  18. Piezoelectric fibers for conformal acoustics.

    PubMed

    Chocat, Noémie; Lestoquoy, Guillaume; Wang, Zheng; Rodgers, Daniel M; Joannopoulos, John D; Fink, Yoel

    2012-10-01

    Ultrasound transducers have many important applications in medical, industrial, and environmental settings. Large-active-area piezoelectric fibers are presented here, which can be woven into extended and flexible ultrasound transducing fabrics. This work opens significant opportunities for large-area, flexible and adjustable acoustic emission and sensing for a variety of emerging applications. PMID:22836955

  19. MTCI acoustic agglomeration particulate control

    SciTech Connect

    Chandran, R.R.; Mansour, M.N.; Scaroni, A.W.; Koopmann, G.H.; Loth, J.L.

    1994-10-01

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

  20. LLNL`s acoustic spectrometer

    SciTech Connect

    Baker, J.

    1997-03-17

    This paper describes the development of a frequency sensitive acoustic transducer that operates in the 10 Hz to 10 kHz regime. This device uses modem silicon microfabrication techniques to form mechanical tines that resonate at specified frequencies. This high-sensitivity device is intended for low-power battery powered applications.

  1. Acoustic Liner for Turbomachinery Applications

    NASA Technical Reports Server (NTRS)

    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.

  2. Determining Equilibrium Position For Acoustical Levitation

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Aveni, G.; Putterman, S.; Rudnick, J.

    1989-01-01

    Equilibrium position and orientation of acoustically-levitated weightless object determined by calibration technique on Earth. From calibration data, possible to calculate equilibrium position and orientation in presence of Earth gravitation. Sample not levitated acoustically during calibration. Technique relies on Boltzmann-Ehrenfest adiabatic-invariance principle. One converts resonant-frequency-shift data into data on normalized acoustical potential energy. Minimum of energy occurs at equilibrium point. From gradients of acoustical potential energy, one calculates acoustical restoring force or torque on objects as function of deviation from equilibrium position or orientation.

  3. Acoustic noise from volcanoes - Theory and experiment

    NASA Technical Reports Server (NTRS)

    Woulff, G.; Mcgetchin, T. R.

    1976-01-01

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

  4. Empirical mode decomposition for analyzing acoustical signals

    NASA Technical Reports Server (NTRS)

    Huang, Norden E. (Inventor)

    2005-01-01

    The present invention discloses a computer implemented signal analysis method through the Hilbert-Huang Transformation (HHT) for analyzing acoustical signals, which are assumed to be nonlinear and nonstationary. The Empirical Decomposition Method (EMD) and the Hilbert Spectral Analysis (HSA) are used to obtain the HHT. Essentially, the acoustical signal will be decomposed into the Intrinsic Mode Function Components (IMFs). Once the invention decomposes the acoustic signal into its constituting components, all operations such as analyzing, identifying, and removing unwanted signals can be performed on these components. Upon transforming the IMFs into Hilbert spectrum, the acoustical signal may be compared with other acoustical signals.

  5. An overview of Arctic Ocean acoustics

    NASA Astrophysics Data System (ADS)

    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.

  6. Parvulescu Revisited: Small Tank Acoustics for Bioacousticians.

    PubMed

    Rogers, Peter H; Hawkins, Anthony D; Popper, Arthur N; Fay, Richard R; Gray, Michael D

    2016-01-01

    Researchers often perform hearing studies on fish in small tanks. The acoustic field in such a tank is considerably different from the acoustic field that occurs in the animal's natural environment. The significance of these differences is magnified by the nature of the fish's auditory system where either acoustic pressure (a scalar), acoustic particle velocity (a vector), or both may serve as the stimulus. It is essential for the underwater acoustician to understand the acoustics of small tanks to be able to carry out valid auditory research in the laboratory and to properly compare and interpret the results of others. PMID:26611052

  7. Robust acoustic wave manipulation of bubbly liquids

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  8. Comments on computational underwater acoustics

    SciTech Connect

    Hedstrom, G.

    1993-04-01

    Two fundamental facts control the choice of computational methods in underwater acoustics. One is that over most of the ocean the sound speed varies much more rapidly with depth than in the horizontal directions. The other is that upon going down from the surface, the sound speed usually decreases to a minimum and then increases from there to the bottom. These properties of the medium imply that the ocean often acts as a waveguide, with energy trapped in a depth-band about the sound-speed minimum. One consequence of these facts is that approximation by normal modes is valid over large regions of the ocean, particularly if correction is made for the slow variation of the modes caused by variation in bottom depth and horizontal variation in sound speed. In portions of the ocean where approximation by normal modes is not valid, we may still often use a paraxial approximation. Paraxial approximations may be used when the wave motion is primarily in a single direction, with slow variation of the signal in directions tangent to the wave front. They are often called ``parabolic`` equations in ocean acoustics, but the term ``paraxial`` is standard in other branches of physics, inducting optics and seismology. Finite-difference approximations are also sometimes used in underwater acoustics, but they are much more computationally intensive than normal modes or paraxial approximations. Finite differences are therefore ordinarily used only where these other methods are not valid, such as in shallow water with rapidly varying depth. One could also use finite elements in these instances, but for acoustics problems finite elements are a special class of finite-difference methods. We discuss finite differences only briefly in this report, because they are not generally used in long-range acoustics.

  9. Comments on computational underwater acoustics

    SciTech Connect

    Hedstrom, G.

    1993-04-01

    Two fundamental facts control the choice of computational methods in underwater acoustics. One is that over most of the ocean the sound speed varies much more rapidly with depth than in the horizontal directions. The other is that upon going down from the surface, the sound speed usually decreases to a minimum and then increases from there to the bottom. These properties of the medium imply that the ocean often acts as a waveguide, with energy trapped in a depth-band about the sound-speed minimum. One consequence of these facts is that approximation by normal modes is valid over large regions of the ocean, particularly if correction is made for the slow variation of the modes caused by variation in bottom depth and horizontal variation in sound speed. In portions of the ocean where approximation by normal modes is not valid, we may still often use a paraxial approximation. Paraxial approximations may be used when the wave motion is primarily in a single direction, with slow variation of the signal in directions tangent to the wave front. They are often called parabolic'' equations in ocean acoustics, but the term paraxial'' is standard in other branches of physics, inducting optics and seismology. Finite-difference approximations are also sometimes used in underwater acoustics, but they are much more computationally intensive than normal modes or paraxial approximations. Finite differences are therefore ordinarily used only where these other methods are not valid, such as in shallow water with rapidly varying depth. One could also use finite elements in these instances, but for acoustics problems finite elements are a special class of finite-difference methods. We discuss finite differences only briefly in this report, because they are not generally used in long-range acoustics.

  10. Acoustic Microfluidics for Bioanalytical Application

    NASA Astrophysics Data System (ADS)

    Lopez, Gabriel

    2013-03-01

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

  11. Soil microstructure and electron microscopy

    NASA Technical Reports Server (NTRS)

    Smart, P.; Fryer, J. R.

    1988-01-01

    As part of the process of comparing Martian soils with terrestial soils, high resolution electron microscopy and associated techniques should be used to examine the finer soil particles, and various techniques of electron and optical microscopy should be used to examine the undisturbed structure of Martian soils. To examine the structure of fine grained portions of the soil, transmission electron microscopy may be required. A striking feature of many Martian soils is their red color. Although the present-day Martian climate appears to be cold, this color is reminiscent of terrestial tropical red clays. Their chemical contents are broadly similar.

  12. Granular acoustic switches and logic elements

    NASA Astrophysics Data System (ADS)

    Li, Feng; Anzel, Paul; Yang, Jinkyu; Kevrekidis, Panayotis G.; Daraio, Chiara

    2014-10-01

    Electrical flow control devices are fundamental components in electrical appliances and computers; similarly, optical switches are essential in a number of communication, computation and quantum information-processing applications. An acoustic counterpart would use an acoustic (mechanical) signal to control the mechanical energy flow through a solid material. Although earlier research has demonstrated acoustic diodes or circulators, no acoustic switches with wide operational frequency ranges and controllability have been realized. Here we propose and demonstrate an acoustic switch based on a driven chain of spherical particles with a nonlinear contact force. We experimentally and numerically verify that this switching mechanism stems from a combination of nonlinearity and bandgap effects. We also realize the OR and AND acoustic logic elements by exploiting the nonlinear dynamical effects of the granular chain. We anticipate these results to enable the creation of novel acoustic devices for the control of mechanical energy flow in high-performance ultrasonic devices.

  13. Electrochemical Processes Enhanced by Acoustic Liquid Manipulation

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C.

    2004-01-01

    Acoustic liquid manipulation is a family of techniques that employ the nonlinear acoustic effects of acoustic radiation pressure and acoustic streaming to manipulate the behavior of liquids. Researchers at the NASA Glenn Research Center are exploring new methods of manipulating liquids for a variety of space applications, and we have found that acoustic techniques may also be used in the normal Earth gravity environment to enhance the performance of existing fluid processes. Working in concert with the NASA Commercial Technology Office, the Great Lakes Industrial Technology Center, and Alchemitron Corporation (Elgin, IL), researchers at Glenn have applied nonlinear acoustic principles to industrial applications. Collaborating with Alchemitron Corporation, we have adapted the devices to create acoustic streaming in a conventional electroplating process.

  14. Method and apparatus for generating acoustic energy

    DOEpatents

    Guerrero, Hector N.

    2002-01-01

    A method and apparatus for generating and emitting amplified coherent acoustic energy. A cylindrical transducer is mounted within a housing, the transducer having an acoustically open end and an acoustically closed end. The interior of the transducer is filled with an active medium which may include scattering nuclei. Excitation of the transducer produces radially directed acoustic energy in the active medium, which is converted by the dimensions of the transducer, the acoustically closed end thereof, and the scattering nuclei, to amplified coherent acoustic energy directed longitudinally within the transducer. The energy is emitted through the acoustically open end of the transducer. The emitted energy can be used for, among other things, effecting a chemical reaction or removing scale from the interior walls of containment vessels.

  15. Method of Adjusting Acoustic Impedances for Impedance-Tunable Acoustic Segments

    NASA Technical Reports Server (NTRS)

    Jones, Kennie H (Inventor); Nark, Douglas M. (Inventor); Jones, Michael G. (Inventor); Parrott, Tony L. (Inventor); Lodding, Kenneth N. (Inventor)

    2012-01-01

    A method is provided for making localized decisions and taking localized actions to achieve a global solution. In an embodiment of the present invention, acoustic impedances for impedance-tunable acoustic segments are adjusted. A first acoustic segment through an N-th acoustic segment are defined. To start the process, the first acoustic segment is designated as a leader and a noise-reducing impedance is determined therefor. This is accomplished using (i) one or more metrics associated with the acoustic wave at the leader, and (ii) the metric(s) associated with the acoustic wave at the N-th acoustic segment. The leader, the N-th acoustic segment, and each of the acoustic segments exclusive of the leader and the N-th acoustic segment, are tuned to the noise-reducing impedance. The current leader is then excluded from subsequent processing steps. The designation of leader is then given one of the remaining acoustic segments, and the process is repeated for each of the acoustic segments through an (N-1)-th one of the acoustic segments.

  16. High-frequency programmable acoustic wave device realized through ferroelectric domain engineering

    SciTech Connect

    Ivry, Yachin E-mail: cd229@eng.cam.ac.uk; Wang, Nan; Durkan, Colm E-mail: cd229@eng.cam.ac.uk

    2014-03-31

    Surface acoustic wave devices are extensively used in contemporary wireless communication devices. We used atomic force microscopy to form periodic macroscopic ferroelectric domains in sol-gel deposited lead zirconate titanate, where each ferroelectric domain is composed of many crystallites, each of which contains many microscopic ferroelastic domains. We examined the electro-acoustic characteristics of the apparatus and found a resonator behavior similar to that of an equivalent surface or bulk acoustic wave device. We show that the operational frequency of the device can be tailored by altering the periodicity of the engineered domains and demonstrate high-frequency filter behavior (>8 GHz), allowing low-cost programmable high-frequency resonators.

  17. Nonlinear Acoustic Evaluation of Creep Damage in Boiler Heat Exchange Tubes

    NASA Astrophysics Data System (ADS)

    Ohtani, Toshihiro; Kawashima, Koichiro; Drew, Michael; Guagliard, Paul

    2007-07-01

    In this study, we evaluated creep damage accumulation in steel welds using the nonlinear acoustic method and microstructural observation. The welds used for the experiment had been employed in boiler exchange tubes of a fossil fuel power plant for 20 years. Samples were cut from the welded region so that they had two planes parallel to the longitudinal direction of the tubes. For the nonlinear acoustic method, we used the immersion technique. Burst waves of 18 MHz were transmitted to the samples, and harmonic waves were detected in the reflection to obtain the images of amplitudes. Increased amplitudes were measured around the heat-affected zone (HAZ), which corresponded to the areas of high creep void density observed by microscopy. The nonlinear acoustic method has been confirmed to have the potential to assess the creep damage.

  18. Creep-Induced Microstructural Changes and Acoustic Characterization in a Cr-Mo-V Steel

    NASA Astrophysics Data System (ADS)

    Ohtani, Toshihiro; Yin, Fuxing; Kamada, Yasuhiro

    2008-05-01

    We studied the evolution of microstructure in a Cr-Mo-V steel (JIS-SNB16) during creep by monitoring ultrasonic attenuation. After obtaining a series of creep samples with various strains under a tensile stress of 25 MPa at 923 K, we removed small samples from the creep samples and measured free vibration resonance frequencies and attenuation coefficients with electromagnetic acoustic resonance (EMAR). EMAR is a combination of the resonant acoustic technique with a non-contact electromagnetic acoustic transducer (EMAT). The attenuation measurement is inherently free from any energy loss, resulting in pure attenuation in a metal sample. Furthermore, we observed the evolution of microstructure with electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The result from the small samples shows the same trend as our previous result from larger sample. We propose a non-destructive method using EMAR to evaluate creep damage in small specimens sampled from structural metals in-service.

  19. Angular spectrum approach for the computation of group and phase velocity surfaces of acoustic waves in anisotropic materials

    PubMed

    Pluta; Schubert; Jahny; Grill

    2000-03-01

    The decomposition of an acoustic wave into its angular spectrum representation creates an effective base for the calculation of wave propagation effects in anisotropic media. In this method, the distribution of acoustic fields is calculated in arbitrary planes from the superposition of the planar components with proper phase shifts. These phase shifts depend on the ratio of the distance between the planes to the normal component of the phase slowness vector. In anisotropic media, the phase shifts depend additionally on the changes of the slowness with respect to the direction of the propagation vector and the polarization. Those relations are obtained from the Christoffel equation. The method employing the fast Fourier transformation algorithm is especially suited for volume imaging in anisotropic media, based on holographic detection in transmission of acoustic waves generated by a point source. This technique is compared with measurements on crystals performed by phase-sensitive scanning acoustic microscopy. PMID:10829665

  20. Fluorescence Microscopy of Single Molecules

    ERIC Educational Resources Information Center

    Zimmermann, Jan; van Dorp, Arthur; Renn, Alois

    2004-01-01

    The investigation of photochemistry and photophysics of individual quantum systems is described with the help of a wide-field fluorescence microscopy approach. The fluorescence single molecules are observed in real time.

  1. STED microscopy resolves nanoparticle assemblies

    NASA Astrophysics Data System (ADS)

    Willig, K. I.; Keller, J.; Bossi, M.; Hell, S. W.

    2006-06-01

    We demonstrate the ability of stimulated emission depletion (STED) microscopy, a far-field fluorescence imaging technique with diffraction-unlimited resolution, to reveal the spatial order of fluorescent nanoparticles. Unlike its confocal counterpart, here STED microscopy resolves the arrangements of densely packed 40 nm beads, supramolecular aggregates in a cell membrane, and colloidal nanoparticles. Both raw and linearly deconvolved data disclose unprecedented details of both biological and non-biological nanopatterns.

  2. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    NASA Astrophysics Data System (ADS)

    Polzikova, N. I.; Alekseev, S. G.; Pyataikin, I. I.; Kotelyanskii, I. M.; Luzanov, V. A.; Orlov, A. P.

    2016-05-01

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

  3. Evaporative self-assembly assisted synthesis of polymeric nanoparticles by surface acoustic wave atomization.

    PubMed

    Friend, James R; Yeo, Leslie Y; Arifin, Dian R; Mechler, Adam

    2008-04-01

    We demonstrate a straightforward and rapid atomization process driven by surface acoustic waves that is capable of continuously producing spherical monodispersed submicron poly-ε-caprolactone particle aggregates between 150 and 200 nm, each of which are composed of nanoparticles of 5-10 nm in diameter. The size and morphologies of these particle assemblies were determined using dynamic light scattering, atomic force microscopy and transmission electron microscopy. Through scaling theory, we show that the larger particle aggregates are formed due to capillary instabilities amplified by the acoustic forcing whereas the smaller particulates that form the aggregates arise due to a nucleate templating process as a result of rapid spatially inhomogeneous solvent evaporation. Minimization of the free energy associated with the evaporative process yields a critical cluster size for a single nucleus in the order of 10 nm, which roughly corresponds with the dimensions of the sub-50 nm particulates. PMID:21817755

  4. Sandia Helicopter Acoustic Detector (SHAD)

    NASA Astrophysics Data System (ADS)

    Arlowe, H. D.

    1982-05-01

    The Sandia Helicopter Acoustic Detector was developed to provide a low cost alternative to radar for countering the helicopter threat at new DOE facilities. The main buildings of these new designs are generally hardened to provide significant delay to a helicopter borne adversary team. Under these circumstances the sensor is only required to detect helicopters that are in their final landing phase and at close range (less than 75 m). This short detection range allows the use of a fairly simple acoustic detection algorithm without making the system overly sensitive to wind noise, motor vehicles, and ventilation/heat exchange blowers. This work was sponsored by the Department of Energy/Office of Safeguards and Security as part of the overall Sandia Fixed Facility Physical Protection Program.

  5. Acoustically driven arrayed waveguide grating.

    PubMed

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

    2015-08-10

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

  6. Study Acoustic Emissions from Composites

    NASA Technical Reports Server (NTRS)

    Walker, James L.; Workman, Gary L.

    1997-01-01

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

  7. Cylindrical acoustic levitator/concentrator

    DOEpatents

    Kaduchak, Gregory; Sinha, Dipen N.

    2002-01-01

    A low-power, inexpensive acoustic apparatus for levitation and/or concentration of aerosols and small liquid/solid samples having particulates up to several millimeters in diameter in air or other fluids is described. It is constructed from a commercially available, hollow cylindrical piezoelectric crystal which has been modified to tune the resonance frequency of the breathing mode resonance of the crystal to that of the interior cavity of the cylinder. When the resonance frequency of the interior cylindrical cavity is matched to the breathing mode resonance of the cylindrical piezoelectric transducer, the acoustic efficiency for establishing a standing wave pattern in the cavity is high. The cylinder does not require accurate alignment of a resonant cavity. Water droplets having diameters greater than 1 mm have been levitated against the force of gravity using; less than 1 W of input electrical power. Concentration of aerosol particles in air is also demonstrated.

  8. Localization in virtual acoustic displays

    NASA Astrophysics Data System (ADS)

    Wenzel, Elizabeth M.

    This paper discusses the development of a particular spatial display medium, the virtual acoustic display. Although the technology can stand alone, it is envisioned ultimately to be a component of a larger multisensory environment and will no doubt find its greatest utility in that context. A general philosophy of the project has been that the development of advanced computer interfaces should be driven first by an understanding of human perceptual requirements, and secondarily by technological capabilities or constraints. In expanding on this view, the paper addresses why virtual acoustic displays are useful, characterizes the abilities of such displays, reviews some recent approaches to their implementation and application, describes the research project at NASA Ames in some detail, and finally outlines some critical research issues for the future.

  9. Acoustic metamaterial design and applications

    NASA Astrophysics Data System (ADS)

    Zhang, Shu

    The explosion of interest in metamaterials is due to the dramatically increased manipulation ability over light as well as sound waves. This material research was stimulated by the opportunity to develop an artificial media with negative refractive index and the application in superlens which allows super-resolution imaging. High-resolution acoustic imaging techniques are the essential tools for nondestructive testing and medical screening. However, the spatial resolution of the conventional acoustic imaging methods is restricted by the incident wavelength of ultrasound. This is due to the quickly fading evanescent fields which carry the subwavelength features of objects. By focusing the propagating wave and recovering the evanescent field, a flat lens with negative-index can potentially overcome the diffraction limit. We present the first experimental demonstration of focusing ultrasound waves through a flat acoustic metamaterial lens composed of a planar network of subwavelength Helmholtz resonators. We observed a tight focus of half-wavelength in width at 60.5 KHz by imaging a point source. This result is in excellent agreement with the numerical simulation by transmission line model in which we derived the effective mass density and compressibility. This metamaterial lens also displays variable focal length at different frequencies. Our experiment shows the promise of designing compact and light-weight ultrasound imaging elements. Moreover, the concept of metamaterial extends far beyond negative refraction, rather giving enormous choice of material parameters for different applications. One of the most interesting examples these years is the invisible cloak. Such a device is proposed to render the hidden object undetectable under the flow of light or sound, by guiding and controlling the wave path through an engineered space surrounding the object. However, the cloak designed by transformation optics usually calls for a highly anisotropic metamaterial, which

  10. Localization in virtual acoustic displays

    NASA Technical Reports Server (NTRS)

    Wenzel, Elizabeth M.

    1992-01-01

    This paper discusses the development of a particular spatial display medium, the virtual acoustic display. Although the technology can stand alone, it is envisioned ultimately to be a component of a larger multisensory environment and will no doubt find its greatest utility in that context. A general philosophy of the project has been that the development of advanced computer interfaces should be driven first by an understanding of human perceptual requirements, and secondarily by technological capabilities or constraints. In expanding on this view, the paper addresses why virtual acoustic displays are useful, characterizes the abilities of such displays, reviews some recent approaches to their implementation and application, describes the research project at NASA Ames in some detail, and finally outlines some critical research issues for the future.

  11. Surface acoustic wave oxygen sensor

    NASA Technical Reports Server (NTRS)

    Collman, James P.; Oglesby, Donald M.; Upchurch, Billy T.; Leighty, Bradley D.; Zhang, Xumu; Herrmann, Paul C.

    1994-01-01

    A surface acoustic wave (SAW) device that responds to oxygen pressure was developed by coating a 158 MHz quartz surface acoustic wave (SAW) device with an oxygen binding agent. Two types of coatings were used. One type was prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer containing the axial ligand. A second type was prepared with an oxygen binding porphyrin solution containing excess axial ligand without a polymer matrix. In the polymer based coatings, the copolymer served to provide the axial ligand to the oxygen binding agent and as a coating matrix on the surface of the SAW device. The oxygen sensing SAW device has been shown to bind oxygen following a Langmuir isotherm and may be used to measure the equilibrium constant of the oxygen binding compound in the coating matrix.

  12. Beamforming in an acoustic shadow

    NASA Technical Reports Server (NTRS)

    Havelock, David; Stinson, Michael; Daigle, Gilles

    1993-01-01

    The sound field deep within an acoustic shadow region is less well understood than that outside the shadow region. Signal levels are substantially lower within the shadow, but beamforming difficulties arise for other reasons such as loss of spatial coherence. Based on analysis of JAPE-91 data, and other data, three types of characteristic signals within acoustic shadow regions are identified. These signal types may correspond to different, intermittent signal propagation conditions. Detection and classification algorithms might take advantage of the signal characteristics. Frequency coherence is also discussed. The extent of coherence across frequencies is shown to be limited, causing difficulties for source classification based on harmonic amplitude relationships. Discussions emphasize short-term characteristics on the order of one second. A video presentation on frequency coherence shows the similarity, in the presence of atmospheric turbulence, between the received signal from a stable set of harmonics generated by a loudspeaker and that received from a helicopter hovering behind a hill.

  13. Acoustic Change Complex: Clinical Implications.

    PubMed

    Kim, Jae-Ryong

    2015-12-01

    The acoustic change complex (ACC) is a cortical auditory evoked potential elicited in response to a change in an ongoing sound. The characteristics and potential clinical implications of the ACC are reviewed in this article. The P1-N1-P2 recorded from the auditory cortex following presentation of an acoustic stimulus is believed to reflect the neural encoding of a sound signal, but this provides no information regarding sound discrimination. However, the neural processing underlying behavioral discrimination capacity can be measured by modifying the traditional methodology for recording the P1-N1-P2. When obtained in response to an acoustic change within an ongoing sound, the resulting waveform is referred to as the ACC. When elicited, the ACC indicates that the brain has detected changes within a sound and the patient has the neural capacity to discriminate the sounds. In fact, results of several studies have shown that the ACC amplitude increases with increasing magnitude of acoustic changes in intensity, spectrum, and gap duration. In addition, the ACC can be reliably recorded with good test-retest reliability not only from listeners with normal hearing but also from individuals with hearing loss, hearing aids, and cochlear implants. The ACC can be obtained even in the absence of attention, and requires relatively few stimulus presentations to record a response with a good signal-to-noise ratio. Most importantly, the ACC shows reasonable agreement with behavioral measures. Therefore, these findings suggest that the ACC might represent a promising tool for the objective clinical evaluation of auditory discrimination and/or speech perception capacity. PMID:26771009

  14. Acoustical coupling of lizard eardrums.

    PubMed

    Christensen-Dalsgaard, Jakob; Manley, Geoffrey A

    2008-12-01

    Lizard ears are clear examples of two-input pressure-difference receivers, with up to 40-dB differences in eardrum vibration amplitude in response to ipsi- and contralateral stimulus directions. The directionality is created by acoustical coupling of the eardrums and interaction of the direct and indirect sound components on the eardrum. The ensuing pressure-difference characteristics generate the highest directionality of any similar-sized terrestrial vertebrate ear. The aim of the present study was to measure the gain of the direct and indirect sound components in three lizard species: Anolis sagrei and Basiliscus vittatus (iguanids) and Hemidactylus frenatus (gekkonid) by laser vibrometry, using either free-field sound or a headphone and coupler for stimulation. The directivity of the ear of these lizards is pronounced in the frequency range from 2 to 5 kHz. The directivity is ovoidal, asymmetrical across the midline, but largely symmetrical across the interaural axis (i.e., front-back). Occlusion of the contralateral ear abolishes the directionality. We stimulated the two eardrums with a coupler close to the eardrum to measure the gain of the sound pathways. Within the frequency range of maximal directionality, the interaural transmission gain (compared to sound arriving directly) is close to or even exceeds unity, indicating a pronounced acoustical transparency of the lizard head and resonances in the interaural cavities. Our results show that the directionality of the lizard ear is caused by the acoustic interaction of the two eardrums. The results can be largely explained by a simple acoustical model based on an electrical analog circuit. PMID:18648878

  15. Longitudinal bulk acoustic mass sensor

    SciTech Connect

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

    2009-07-20

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

  16. Nonlinear positron acoustic solitary waves

    SciTech Connect

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

    2009-07-15

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

  17. Acoustical Coupling of Lizard Eardrums

    PubMed Central

    Manley, Geoffrey A.

    2008-01-01

    Lizard ears are clear examples of two-input pressure-difference receivers, with up to 40-dB differences in eardrum vibration amplitude in response to ipsi- and contralateral stimulus directions. The directionality is created by acoustical coupling of the eardrums and interaction of the direct and indirect sound components on the eardrum. The ensuing pressure-difference characteristics generate the highest directionality of any similar-sized terrestrial vertebrate ear. The aim of the present study was to measure the gain of the direct and indirect sound components in three lizard species: Anolis sagrei and Basiliscus vittatus (iguanids) and Hemidactylus frenatus (gekkonid) by laser vibrometry, using either free-field sound or a headphone and coupler for stimulation. The directivity of the ear of these lizards is pronounced in the frequency range from 2 to 5 kHz. The directivity is ovoidal, asymmetrical across the midline, but largely symmetrical across the interaural axis (i.e., front–back). Occlusion of the contralateral ear abolishes the directionality. We stimulated the two eardrums with a coupler close to the eardrum to measure the gain of the sound pathways. Within the frequency range of maximal directionality, the interaural transmission gain (compared to sound arriving directly) is close to or even exceeds unity, indicating a pronounced acoustical transparency of the lizard head and resonances in the interaural cavities. Our results show that the directionality of the lizard ear is caused by the acoustic interaction of the two eardrums. The results can be largely explained by a simple acoustical model based on an electrical analog circuit. PMID:18648878

  18. Localization algorithm for acoustic emission

    NASA Astrophysics Data System (ADS)

    Salinas, V.; Vargas, Y.; Ruzzante, J.; Gaete, L.

    2010-01-01

    In this paper, an iterative algorithm for localization of acoustic emission (AE) source is presented. The main advantage of the system is that it is independent of the 'ability' in the determination of signal level to triggering the signal by the researcher. The system was tested in cylindrical samples with an AE localized in a known position; the precision in the source determination was of about 2 mm, better than the precision obtained with classic localization algorithms (˜1 cm).

  19. Solid Rocket Motor Acoustic Testing

    SciTech Connect

    Rogers, J.D.

    1999-03-31

    Acoustic data are often required for the determination of launch and powered flight loads for rocket systems and payloads. Such data are usually acquired during test firings of the solid rocket motors. In the current work, these data were obtained for two tests at a remote test facility where we were visitors. This paper describes the data acquisition and the requirements for working at a remote site, interfacing with the test hosts.

  20. Acoustic radiation stress in solids

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Yost, William T.

    1986-01-01

    It is shown that the radiation-induced static strains associated with acoustic waves propagating in solids are obtained directly from the virial theorem for an elastic continuum and that the radiation stresses result from combining the virial theorem with the Boltzmann-Ehrenfest principle of adiabatic invariance. The experimental confirmation of critical theoretical predictions in solids is reported. The implications of the results for the fundamental thermal properties of crystals are addressed.

  1. Acoustic Change Complex: Clinical Implications

    PubMed Central

    2015-01-01

    The acoustic change complex (ACC) is a cortical auditory evoked potential elicited in response to a change in an ongoing sound. The characteristics and potential clinical implications of the ACC are reviewed in this article. The P1-N1-P2 recorded from the auditory cortex following presentation of an acoustic stimulus is believed to reflect the neural encoding of a sound signal, but this provides no information regarding sound discrimination. However, the neural processing underlying behavioral discrimination capacity can be measured by modifying the traditional methodology for recording the P1-N1-P2. When obtained in response to an acoustic change within an ongoing sound, the resulting waveform is referred to as the ACC. When elicited, the ACC indicates that the brain has detected changes within a sound and the patient has the neural capacity to discriminate the sounds. In fact, results of several studies have shown that the ACC amplitude increases with increasing magnitude of acoustic changes in intensity, spectrum, and gap duration. In addition, the ACC can be reliably recorded with good test-retest reliability not only from listeners with normal hearing but also from individuals with hearing loss, hearing aids, and cochlear implants. The ACC can be obtained even in the absence of attention, and requires relatively few stimulus presentations to record a response with a good signal-to-noise ratio. Most importantly, the ACC shows reasonable agreement with behavioral measures. Therefore, these findings suggest that the ACC might represent a promising tool for the objective clinical evaluation of auditory discrimination and/or speech perception capacity. PMID:26771009

  2. Measurement of local internal friction in metallic glasses

    SciTech Connect

    Wagner, H.; Büchsenschütz-Göbeler, M.; Luo, Y.; Samwer, K.; Kumar, A.; Arnold, W.

    2014-04-07

    Atomic force acoustic microscopy (AFAM), an advanced scanning probe microscopy technique, has been used to measure local elastic properties with a spatial resolution given by the tip-sample contact radius. AFAM is based on inducing out-of-plane vibrations in the specimen. The vibrations are sensed by the AFM cantilever from by the photodiode signal when its tip is in contact with the material under test. To measure local damping, the inverse quality factor Q{sup −1} of the resonance curve is usually evaluated. Here, from the contact-resonance spectra obtained, we determine the real and imaginary part of the contact stiffness k* and from these two quantities the local damping factor Q{sub loc}{sup −1} is obtained which is proportional to the imaginary part γ of the contact stiffness. The evaluation of the data is based on the cantilever's mass distribution with damped flexural modes and not on an effective point-mass approximation for the cantilever’s motion. The given equation is simple to use and has been employed to study the local Q{sub loc}{sup −1} of amorphous PdCuSi metallic glass and its crystalline counterpart as a function of position of the AFM tip on the surface. The width of the distribution changes dramatically from the amorphous to the crystalline state as expected from the consequences of the potential-energy landscape picture. The center value of the distribution curve for Q{sub loc}{sup −1} coincides very well with published data, based on global ultrasonic or internal friction measurements. This is compared to Q{sub loc}{sup −1} measured in crystalline SrTiO{sub 3}, which exhibits a narrow distribution, as expected.

  3. 3D acoustic atmospheric tomography

    NASA Astrophysics Data System (ADS)

    Rogers, Kevin; Finn, Anthony

    2014-10-01

    This paper presents a method for tomographically reconstructing spatially varying 3D atmospheric temperature profiles and wind velocity fields based. Measurements of the acoustic signature measured onboard a small Unmanned Aerial Vehicle (UAV) are compared to ground-based observations of the same signals. The frequency-shifted signal variations are then used to estimate the acoustic propagation delay between the UAV and the ground microphones, which are also affected by atmospheric temperature and wind speed vectors along each sound ray path. The wind and temperature profiles are modelled as the weighted sum of Radial Basis Functions (RBFs), which also allow local meteorological measurements made at the UAV and ground receivers to supplement any acoustic observations. Tomography is used to provide a full 3D reconstruction/visualisation of the observed atmosphere. The technique offers observational mobility under direct user control and the capacity to monitor hazardous atmospheric environments, otherwise not justifiable on the basis of cost or risk. This paper summarises the tomographic technique and reports on the results of simulations and initial field trials. The technique has practical applications for atmospheric research, sound propagation studies, boundary layer meteorology, air pollution measurements, analysis of wind shear, and wind farm surveys.

  4. Acoustic purification of extracellular microvesicles.

    PubMed

    Lee, Kyungheon; Shao, Huilin; Weissleder, Ralph; Lee, Hakho

    2015-03-24

    Microvesicles (MVs) are an increasingly important source for biomarker discovery and clinical diagnostics. The small size of MVs and their presence in complex biological environment, however, pose technical challenges in sample preparation, particularly when sample volumes are small. We herein present an acoustic nanofilter system that size-specifically separates MVs in a continuous and contact-free manner. The separation uses ultrasound standing waves to exert differential acoustic force on MVs according to their size and density. By optimizing the design of the ultrasound transducers and underlying electronics, we were able to achieve a high separation yield and resolution. The "filter size-cutoff" can be controlled electronically in situ, which enables versatile MV-size selection. We applied the acoustic nanofilter to isolate nanoscale (<200 nm) vesicles from cell culture media as well as MVs in stored red blood cell products. With the capacity for rapid and contact-free MV isolation, the developed system could become a versatile preparatory tool for MV analyses. PMID:25672598

  5. Acoustic Purification of Extracellular Microvesicles

    PubMed Central

    Lee, Kyungheon; Shao, Huilin; Weissleder, Ralph; Lee, Hakho

    2015-01-01

    Microvesicles (MVs) are an increasingly important source for biomarker discovery and clinical diagnostics. The small size of MVs and their presence in complex biological environment, however, pose practical technical challenges, particularly when sample volumes are small. We herein present an acoustic nano-filter system that size-specifically separates MVs in a continuous and contact-free manner. The separation is based on ultrasound standing waves that exert differential acoustic force on MVs according to their size and density. By optimizing the design of the ultrasound transducers and underlying electronics, we were able to achieve a high separation yield and resolution. The “filter size-cutoff” can be controlled electronically in situ and enables versatile MV-size selection. We applied the acoustic nano-filter to isolate nanoscale (<200 nm) vesicles from cell culture media as well as MVs in stored red blood cell products. With the capacity for rapid and contact-free MV isolation, the developed system could become a versatile preparatory tool for MV analyses. PMID:25672598

  6. An Approach for Characterizing and Comparing Hyperspectral Microscopy Systems

    PubMed Central

    Annamdevula, Naga S.; Sweat, Brenner; Favreau, Peter; Lindsey, Ashley S.; Alvarez, Diego F.; Rich, Thomas C.; Leavesley, Silas J.

    2013-01-01

    Hyperspectral imaging and analysis approaches offer accurate detection and quantification of fluorescently-labeled proteins and cells in highly autofluorescent tissues. However, selecting optimum acquisition settings for hyperspectral imaging is often a daunting task. In this study, we compared two hyperspectral systems—a widefield system with acoustic optical tunable filter (AOTF) and charge coupled device (CCD) camera, and a confocal system with diffraction gratings and photomultiplier tube (PMT) array. We measured the effects of system parameters on hyperspectral image quality and linear unmixing results. Parameters that were assessed for the confocal system included pinhole diameter, laser power, PMT gain and for the widefield system included arc lamp intensity, and camera gain. The signal-to-noise ratio (SNR) and the root-mean-square error (RMS error) were measured to assess system performance. Photobleaching dynamics were studied. Finally, theoretical sensitivity studies were performed to estimate the incremental response (sensitivity) and false-positive detection rates (specificity). Results indicate that hyperspectral imaging assays are highly dependent on system parameters and experimental conditions. For detection of green fluorescent protein (GFP)-expressing cells in fixed lung tissues, a confocal pinhole of five airy disk units, high excitation intensity and low detector gain were optimal. The theoretical sensitivity studies revealed that widefield hyperspectral microscopy was able to detect GFP with fewer false positive occurrences than confocal microscopy, even though confocal microscopy offered improved signal and noise characteristics. These studies provide a framework for optimization that can be applied to a variety of hyperspectral imaging systems. PMID:23877125

  7. An approach for characterizing and comparing hyperspectral microscopy systems.

    PubMed

    Annamdevula, Naga S; Sweat, Brenner; Favreau, Peter; Lindsey, Ashley S; Alvarez, Diego F; Rich, Thomas C; Leavesley, Silas J

    2013-01-01

    Hyperspectral imaging and analysis approaches offer accurate detection and quantification of fluorescently-labeled proteins and cells in highly autofluorescent tissues. However, selecting optimum acquisition settings for hyperspectral imaging is often a daunting task. In this study, we compared two hyperspectral systems-a widefield system with acoustic optical tunable filter (AOTF) and charge coupled device (CCD) camera, and a confocal system with diffraction gratings and photomultiplier tube (PMT) array. We measured the effects of system parameters on hyperspectral image quality and linear unmixing results. Parameters that were assessed for the confocal system included pinhole diameter, laser power, PMT gain and for the widefield system included arc lamp intensity, and camera gain. The signal-to-noise ratio (SNR) and the root-mean-square error (RMS error) were measured to assess system performance. Photobleaching dynamics were studied. Finally, theoretical sensitivity studies were performed to estimate the incremental response (sensitivity) and false-positive detection rates (specificity). Results indicate that hyperspectral imaging assays are highly dependent on system parameters and experimental conditions. For detection of green fluorescent protein (GFP)-expressing cells in fixed lung tissues, a confocal pinhole of five airy disk units, high excitation intensity and low detector gain were optimal. The theoretical sensitivity studies revealed that widefield hyperspectral microscopy was able to detect GFP with fewer false positive occurrences than confocal microscopy, even though confocal microscopy offered improved signal and noise characteristics. These studies provide a framework for optimization that can be applied to a variety of hyperspectral imaging systems. PMID:23877125

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

    NASA Astrophysics Data System (ADS)

    Djojodihardjo, Harijono

    2015-03-01

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

  9. Acoustic effects of single electrostatic discharges

    NASA Astrophysics Data System (ADS)

    Orzech, Łukasz

    2015-10-01

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

  10. Acoustic levitation of a large solid sphere

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  11. Frustrated total internal reflection acoustic field sensor

    DOEpatents

    Kallman, Jeffrey S.

    2000-01-01

    A frustrated total internal reflection acoustic field sensor which allows the acquisition of the acoustic field over an entire plane, all at once. The sensor finds use in acoustic holography and acoustic diffraction tomography. For example, the sensor may be produced by a transparent plate with transparent support members tall enough to support one or more flexible membranes at an appropriate height for frustrated total internal reflection to occur. An acoustic wave causes the membrane to deflect away from its quiescent position and thus changes the amount of light that tunnels through the gap formed by the support members and into the membrane, and so changes the amount of light reflected by the membrane. The sensor(s) is illuminated by a uniform tight field, and the reflection from the sensor yields acoustic wave amplitude and phase information which can be picked up electronically or otherwise.

  12. Acoustic Waves in Medical Imaging and Diagnostics

    PubMed Central

    Sarvazyan, Armen P.; Urban, Matthew W.; Greenleaf, James F.

    2013-01-01

    Up until about two decades ago acoustic imaging and ultrasound imaging were synonymous. The term “ultrasonography,” or its abbreviated version “sonography” meant an imaging modality based on the use of ultrasonic compressional bulk waves. Since the 1990s numerous acoustic imaging modalities started to emerge based on the use of a different mode of acoustic wave: shear waves. It was demonstrated that imaging with these waves can provide very useful and very different information about the biological tissue being examined. We will discuss physical basis for the differences between these two basic modes of acoustic waves used in medical imaging and analyze the advantages associated with shear acoustic imaging. A comprehensive analysis of the range of acoustic wavelengths, velocities, and frequencies that have been used in different imaging applications will be presented. We will discuss the potential for future shear wave imaging applications. PMID:23643056

  13. Reflection properties of gravito-acoustic waves

    NASA Astrophysics Data System (ADS)

    Jovanović, Gordana

    2016-03-01

    We derive the dispersion equation for gravito-acoustic waves in an isothermal gravitationally stratified nonmagnetized atmosphere. In this model, with constant sound speed, it is possible to derive analytically the equations for gravito-acoustic waves. The large value of the viscous Reynolds number in the solar atmosphere imply that the dissipative terms in HD (hydrodynamics) equations are negligible. We consider the plane boundary z = 0 between two isothermal atmosphere regions and using the boundary conditions we derive the equation for the reflection coeffcient of gravito-acoustic waves. For the frequencies much greater than acoustic cutoff frequency, the reflection coefficient of the acoustic waves modified by gravity is the same as in the case of the pure acoustic waves. Reflection coefficient for the gravity waves is very high, R ≈ 1.

  14. Acoustic Inspection Device V1.0

    2002-01-16

    The Acoustic Inspection Device (AID) is an instrument used to interrogate materials with ultrasonic acoustic waves. The AID application software program runs under the Microsoft Windows 98 or Windows 2000 operating system. Is serves as the instrument controller and provides the user interface for the instrument known as the Acoustic Inspection Device (AID). The program requests, acquires, and analyzes acoustic waveforms from the AID hardware (pulser/receiver module, digitizer, and communications link). Graphical user displays ofmore » the AID application program include the real-time display of ultrasonic acoustic waveforms and analytical results including acoustic time-of-flight, velocity, and material identification. This program utilizes a novel algorithm, developed at PNNL, that automatically extracts the time-of-flight and amplitude data from the raw waveform and compares the extracted data to a material database.« less

  15. Chromospheric heating by acoustic shock waves

    NASA Technical Reports Server (NTRS)

    Jordan, Stuart D.

    1993-01-01

    Work by Anderson & Athay (1989) suggests that the mechanical energy required to heat the quiet solar chromosphere might be due to the dissipation of weak acoustic shocks. The calculations reported here demonstrate that a simple picture of chromospheric shock heating by acoustic waves propagating upward through a model solar atmosphere, free of both magnetic fields and local inhomogeneities, cannot reproduce their chromospheric model. The primary reason is the tendency for vertically propagating acoustic waves in the range of allowed periods to dissipate too low in the atmosphere, providing insufficient residual energy for the middle chromosphere. The effect of diverging magnetic fields and the corresponding expanding acoustic wavefronts on the mechanical dissipation length is then discussed as a means of preserving a quasi-acoustic heating hypothesis. It is argued that this effect, in a canopy that overlies the low chromosphere, might preserve the acoustic shock hypothesis consistent with the chromospheric radiation losses computed by Anderson & Athay.

  16. Acoustic Measurements of Small Solid Rocket Motor

    NASA Technical Reports Server (NTRS)

    Vargas, Magda B.; Kenny, R. Jeremy

    2010-01-01

    Rocket acoustic noise can induce loads and vibration on the vehicle as well as the surrounding structures. Models have been developed to predict these acoustic loads based on scaling existing solid rocket motor data. The NASA Marshall Space Flight Center acoustics team has measured several small solid rocket motors (thrust below 150,000 lbf) to anchor prediction models. This data will provide NASA the capability to predict the acoustic environments and consequent vibro-acoustic response of larger rockets (thrust above 1,000,000 lbf) such as those planned for the NASA Constellation program. This paper presents the methods used to measure acoustic data during the static firing of small solid rocket motors and the trends found in the data.

  17. Coupling between plate vibration and acoustic radiation

    NASA Technical Reports Server (NTRS)

    Frendi, Abdelkader; Maestrello, Lucio; Bayliss, Alvin

    1992-01-01

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

  18. Integrated optical, acoustically tunable wavelength filter

    NASA Astrophysics Data System (ADS)

    Frangen, J.; Herrmann, H.; Ricken, R.; Seibert, H.; Sohler, W.

    1989-11-01

    A TM/TE convertor is combined with a TE-pass polarizer on a common LiNbO3 chip to obtain an integrated optical, acoustically tunable wavelength filter. Its tuning range is 1.45-1.57 micron wavelength with a filter half-width of 2.8 nm. Due to the combined acoustical/optical strip guide structure used in the mode convertor, a very low acoustic drive power of only 9 mW is required.

  19. Acoustic resonance frequency locked photoacoustic spectrometer

    DOEpatents

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

    2003-09-09

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

  20. Acoustical scale modeling of roadway traffic noise

    SciTech Connect

    Anderson, G.S.

    1980-03-01

    During the planning and design of any federally assisted highway project, noise levels must be predicted for the highway in its operational mode. The use of an acoustical scale modeling technique to predict roadway traffic noise is described. Literature pertaining to acoustical scale modeling of outdoor noise propagation, particularly roadway noise, is reviewed. Field and laboratory measurements validated the predictions of the acoustical scale modeling technique. (1 photo)