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Sample records for acoustic energy emitted

  1. 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.

  2. Surface acoustic wave-driven planar light-emitting device

    NASA Astrophysics Data System (ADS)

    Cecchini, Marco; De Simoni, Giorgio; Piazza, Vincenzo; Beltram, Fabio; Beere, H. E.; Ritchie, D. A.

    2004-10-01

    Electroluminescence emission controlled by means of surface acoustic waves (SAWs) in planar light-emitting diodes (pLEDs) is demonstrated. Interdigital transducers for SAW generation were integrated onto pLEDs fabricated following the scheme which we have recently developed [Cecchini et al., Appl. Phys. Lett. 82, 636 (2003)]. Current-voltage, light-voltage, and photoluminescence characteristics are presented at cryogenic temperatures. We argue that this scheme represents a valuable building block for advanced optoelectronic architectures.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Acoustic energy in ducts - Further observations

    NASA Technical Reports Server (NTRS)

    Eversman, W.

    1979-01-01

    The transmission of acoustic energy in uniform ducts carrying uniform flow is investigated with the purpose of clarifying two points of interest. The two commonly used definitions of acoustic 'energy' flux are shown to be related by a Legendre transformation of the Lagrangian density exactly as in deriving the Hamiltonian density in mechanics. In the acoustic case the total energy density and the Hamiltonian density are not the same which accounts for two different 'energy' fluxes. When the duct has acoustically absorptive walls neither of the two flux expressions gives correct results. A reevaluation of the basis of derivation of the energy density and energy flux provides forms which yield consistent results for soft walled ducts.

  8. Acoustic wave emitted by a vortex ring passing near the edge of a half-plane

    NASA Astrophysics Data System (ADS)

    Kambe, T.; Minota, T.; Ikushima, Y.

    1985-06-01

    Acoustic emission by vortex-edge interaction is investigated both theoretically and experimentally. The theory of vortex sound enables the representation of the far-field pressure in terms of the vortex motion near the half-plane edge. It is found that the pressure p depends on the product of an angular factor representing directionality and a time factor representing wave profile. The pressure formula leads to a specified scaling law for the sound emitted by a vortex ring. The vortex ring used in the experiment had radius about 4.7 mm and velocity ranging from 29 to 61 m/s. The above scaling law of the pressure and the cardioid directionality of the intensity were reproduced in the experiment with reasonable accuracy.

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

  10. Acoustic Energy Estimates in Inhomogeneous Moving Media

    NASA Technical Reports Server (NTRS)

    Farassat, F.; Farris, Mark

    1999-01-01

    In ducted fan engine noise research, there is a need for defining a simple and easy to use acoustic energy conservation law to help in quantification of noise control techniques. There is a well known conservation law relating acoustic energy and acoustic energy flux in the case of an isentropic irrotational flow. Several different approaches have been taken to generalize this conservation law. For example, Morfey finds an identity by separating out the irrotational part of the perturbed flow. Myers is able to find a series of indentities by observing an algebraic relationship between the basic conservation of energy equation for a background flow and the underlying equations of motion. In an approximate sense, this algebraic relationship is preserved under perturbation. A third approach which seems to have not been pursued in the literature is a result known as Noether's theorem. There is a Lagrangian formulation for the Euler equation of fluid mechanics. Noether's theorem says that any group action that leaves the Lagrangian action invariant leads to a conserved quantity. This presentation will include a survey of current results regarding acoustic energy and preliminary results on the symmetries of the Lagrangian.

  11. Properties of acoustic energy quantities

    NASA Astrophysics Data System (ADS)

    Uosukainen, Seppo

    1989-09-01

    The sound power of a source is shown to depend on other sources and environment through the coherent and incoherent interaction and on the mounting conditions of the source. The conditions for a source to be a constant power source (being a rare exception amoung sound sources) are defined. A new quantity semianalytic intensity is defined. By its help the mean value, time-dependent, active and reactive intensity are defined in general time-dependent fields. In time harmonic fields the active part of the mean value intensity is rotational. The rotationality is proportional to the polarization vector of particle velocity, the polarization being elliptical in general. The changes of sound field are shown to generate rotationality in all intensity components. The negative pI-indicator is shown to be a possible indication of the rotationality of intensity. Fundamental intensity vortices are defined. The size of the lowest order vortices is of the order of 0.5 to 0.7 (Lambda). A modified J.M.C. method is developed for the basis of the vector and dyadic weighting, the former of which weights the sound pressure and particle velocity differently, and the latter also changes the polarization (or direction) of the particle velocity. Theoretical possibilities of general field modifications and acoustic sink optimization based on these new field reshapers are presented. A new field indicator for intensity measurements is defined. It can be used as a measure of the diffuseness and reactivity as a function of time and observation direction.

  12. Zebra mussel control using acoustic energy

    SciTech Connect

    Tiller, G.W.; Gaucher, T.A.; Menezes, J.K.; Dolat, S.W. )

    1992-01-01

    A practical and economical device or method that reduces zebra mussel colonization without detrimental side effects is highly desirable. An ideal method is one that could be installed near, on, or in existing raw water intakes and conduits. It must have a known effect that is limited to a defined area, should have maximum effects on a targeted species, and preferably have a low life cycle cost than the current alternative methods of control and maintenance. Underwater sound could be such a desirable solution, if found to be an effective control measure for zebra mussels. Although sound most often applies specifically to acoustic energy that is audible to humans, 20 Hertz (Hz) to 20 kiloHertz (kHz), in this report we will use the terms sound and acoustic to include acoustic energy between 100 Hz and 100 MegaHertz (MHz). This research on zebra mussel biofouling is designed to effect the early developmental stages in the life cycle of Dreissena polymorpha (Pallas). Vulnerable stages in the development of D. polymorpha that might yield to site-specific acoustic deterrence measures include the free-swimming larval veliger stage, the postveliger pre-attachment demersal stage, and the immediate post-attachment stage. The proposed applications include surface treatment to prevent, reduce or eliminate colonization on underwater structures, and the stream treatment to reduce or eliminate (destroy) mussel larvae entrained in a moving volume of water.

  13. Acoustical problems in high energy pulsed E-beams lasers

    NASA Technical Reports Server (NTRS)

    Horton, T. E.; Wylie, K. F.

    1976-01-01

    During the pulsing of high energy, CO2, electron beam lasers, a significant fraction of input energy ultimately appears as acoustical disturbances. The magnitudes of these disturbances were quantified by computer analysis. Acoustical and shock impedance data are presented on materials (Rayleigh type) which show promise in controlling acoustical disturbance in E-beam systems.

  14. Implosion of an underwater spark-generated bubble and acoustic energy evaluation using the Rayleigh model.

    PubMed

    Buogo, Silvano; Cannelli, Giovanni B

    2002-06-01

    The growth, collapse, and rebound of a vapor bubble generated by an underwater spark is studied by means of high-speed cinematography, simultaneously acquiring the emitted acoustic signature. Video recordings show that the growth and collapse phases are nearly symmetrical during the first two or three cycles, the bubble shape being approximately spherical. After 2-3 cycles the bubble behavior changes from a collapsing/rebounding regime with sound-emitting implosions to a pulsating regime with no implosions. The motion of the bubble wall during the first collapses was found to be consistent with the Rayleigh model of a cavity in an incompressible liquid, with the inclusion of a vapor pressure term at constant temperature within each bubble cycle. An estimate of the pressure inside the bubble is obtained measuring the collapse time and maximum radius, and the amount of energy converted into acoustical energy upon each implosion is deduced. The resulting value of acoustic efficiency was found to be in agreement with measurements based on the emitted acoustic pulse. PMID:12083190

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  17. Energy Efficient Engine acoustic supporting technology report

    NASA Technical Reports Server (NTRS)

    Lavin, S. P.; Ho, P. Y.

    1985-01-01

    The acoustic development of the Energy Efficient Engine combined testing and analysis using scale model rigs and an integrated Core/Low Spool demonstration engine. The scale model tests show that a cut-on blade/vane ratio fan with a large spacing (S/C = 2.3) is as quiet as a cut-off blade/vane ratio with a tighter spacing (S/C = 1.27). Scale model mixer tests show that separate flow nozzles are the noisiest, conic nozzles the quietest, with forced mixers in between. Based on projections of ICLS data the Energy Efficient Engine (E3) has FAR 36 margins of 3.7 EPNdB at approach, 4.5 EPNdB at full power takeoff, and 7.2 EPNdB at sideline conditions.

  18. Acoustic confort at home: Noise emitted by house installations. Recommendations in order to avoid such noise

    NASA Astrophysics Data System (ADS)

    Jimenez, Santiago

    2002-11-01

    The present survey consists of the analysis and the study of the solutions used at present in the installations of water supply and elevators. It has been carried out from the acoustic point of view. In order to achieve a thorough study a pilot plant was built in the Laboratory of Acoustics of the School of Industrial Engineering of Terrassa. This pilot plant reproduced different kinds of installations of the water supply in houses. And it has allowed us to systematize the measures and also to determine the optimum solutions from the acoustic perspective. In accordance with the objectives and the process of the survey, the solutions regularly employed in the facilities of water supply and elevators in houses have been analyzed, and levels of noise associated to these facilities have been also presented. A summary of the results obtained in the plant has been included, according to diverse variables. Both the conclusions of the analysis of the data obtained in the laboratory and those of the installations of the houses have been also compared, which has allowed us to describe a series of suggestions with the purpose of reducing the acoustic emission of this type of installations, and increase the acoustic comfort at home. (To be presented in Spanish.)

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

    NASA Astrophysics Data System (ADS)

    Harne, Ryan L.; Lynd, Danielle T.

    2016-08-01

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

  20. Acoustic energy-driven fluid pump and method

    SciTech Connect

    Janus, Michael C.; Richards, George A.; Robey, Edward H.

    1997-12-01

    Bulk fluid motion is promoted in a gaseous fluid contained within a conduit system provided with a diffuser without the need for a mean pressure differential across the conduit system. The contacting of the gaseous fluid with unsteady energy at a selected frequency and pressure amplitude induces fluid flow through the conical diffuser. The unsteady energy can be provided by pulse combustors, thermoacoustic engines, or acoustic energy generators such as acoustic speakers.

  1. Simple Experimental Verification of the Relation between the Band-Gap Energy and the Energy of Photons Emitted by LEDs

    ERIC Educational Resources Information Center

    Precker, Jurgen W.

    2007-01-01

    The wavelength of the light emitted by a light-emitting diode (LED) is intimately related to the band-gap energy of the semiconductor from which the LED is made. We experimentally estimate the band-gap energies of several types of LEDs, and compare them with the energies of the emitted light, which ranges from infrared to white. In spite of…

  2. Acoustic energy transmission in cast iron pipelines

    NASA Astrophysics Data System (ADS)

    Kiziroglou, Michail E.; Boyle, David E.; Wright, Steven W.; Yeatman, Eric M.

    2015-12-01

    In this paper we propose acoustic power transfer as a method for the remote powering of pipeline sensor nodes. A theoretical framework of acoustic power propagation in the ceramic transducers and the metal structures is drawn, based on the Mason equivalent circuit. The effect of mounting on the electrical response of piezoelectric transducers is studied experimentally. Using two identical transducer structures, power transmission of 0.33 mW through a 1 m long, 118 mm diameter cast iron pipe, with 8 mm wall thickness is demonstrated, at 1 V received voltage amplitude. A near-linear relationship between input and output voltage is observed. These results show that it is possible to deliver significant power to sensor nodes through acoustic waves in solid structures. The proposed method may enable the implementation of acoustic - powered wireless sensor nodes for structural and operation monitoring of pipeline infrastructure.

  3. Characterization of energy trapping in a bulk acoustic wave resonator

    NASA Astrophysics Data System (ADS)

    Kokkonen, Kimmo; Meltaus, Johanna; Pensala, Tuomas; Kaivola, Matti

    2010-12-01

    Acoustic wave fields both within the active electrode area of a solidly mounted 1.8 GHz bulk acoustic wave resonator, and around it in the surrounding region, are measured using a heterodyne laser interferometer. Plate-wave dispersion diagrams for both regions are extracted from the measurement data. The experimental dispersion data reveal the cutoff frequencies of the acoustic vibration modes in the region surrounding the resonator, and, therefore, the energy trapping range of the resonator can readily be determined. The measured dispersion properties of the surrounding region, together with the abruptly diminishing amplitude of the dispersion curves in the resonator, signal the onset of acoustic leakage from the resonator. This information is important for verifying and further developing the simulation tools used for the design of the resonators. Experimental wave field images, dispersion diagrams for both regions, and the threshold for energy leakage are discussed.

  4. Detection of Large Acoustic Energy Flux in the Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Bello González, N.; Franz, M.; Martínez Pillet, V.; Bonet, J. A.; Solanki, S. K.; del Toro Iniesta, J. C.; Schmidt, W.; Gandorfer, A.; Domingo, V.; Barthol, P.; Berkefeld, T.; Knölker, M.

    2010-11-01

    We study the energy flux carried by acoustic waves excited by convective motions at sub-photospheric levels. The analysis of high-resolution spectropolarimetric data taken with IMaX/SUNRISE provides a total energy flux of ~6400-7700 W m-2 at a height of ~250 km in the 5.2-10 mHz range, i.e., at least twice the largest energy flux found in previous works. Our estimate lies within a factor of two of the energy flux needed to balance radiative losses from the chromosphere according to the estimates of Anderson & Athay and revives interest in acoustic waves for transporting energy to the chromosphere. The acoustic flux is mainly found in the intergranular lanes but also in small rapidly evolving granules and at the bright borders, forming dark dots and lanes of splitting granules.

  5. Converting acoustic energy into useful other energy forms

    DOEpatents

    Putterman, Seth J.; Barber, Bradley Paul; Hiller, Robert Anthony; Lofstedt, Ritva Maire Johanna

    1997-01-01

    Sonoluminescence is an off-equilibrium phenomenon in which the energy of a resonant sound wave in a liquid is highly concentrated so as to generate flashes of light. The conversion of sound to light represents an energy amplification of eleven orders of magnitude. The flashes which occur once per cycle of the audible or ultrasonic sound fields can be comprised of over one million photons and last for less 100 picoseconds. The emission displays a clocklike synchronicity; the jitter in time between consecutive flashes is less than fifty picoseconds. The emission is blue to the eye and has a broadband spectrum increasing from 700 nanometers to 200 nanometers. The peak power is about 100 milliWatts. The initial stage of the energy focusing is effected by the nonlinear oscillations of a gas bubble trapped in the liquid. For sufficiently high drive pressures an imploding shock wave is launched into the gas by the collapsing bubble. The reflection of the shock from its focal point results in high temperatures and pressures. The sonoluminescence light emission can be sustained by sensing a characteristic of the emission and feeding back changes into the driving mechanism. The liquid is in a sealed container and the seeding of the gas bubble is effected by locally heating the liquid after sealing the container. Different energy forms than light can be obtained from the converted acoustic energy. When the gas contains deuterium and tritium there is the feasibility of the other energy form being fusion, namely including the generation of neutrons.

  6. Sound insulation and energy harvesting based on acoustic metamaterial plate

    NASA Astrophysics Data System (ADS)

    Assouar, Badreddine; Oudich, Mourad; Zhou, Xiaoming

    2015-03-01

    The emergence of artificially designed sub-wavelength acoustic materials, denoted acoustic metamaterials (AMM), has significantly broadened the range of materials responses found in nature. These engineered materials can indeed manipulate sound/vibration in surprising ways, which include vibration/sound insulation, focusing, cloaking, acoustic energy harvesting …. In this work, we report both on the analysis of the airborne sound transmission loss (STL) through a thin metamaterial plate and on the possibility of acoustic energy harvesting. We first provide a theoretical study of the airborne STL and confronted them to the structure-borne dispersion of a metamaterial plate. Second, we propose to investigate the acoustic energy harvesting capability of the plate-type AMM. We have developed semi-analytical and numerical methods to investigate the STL performances of a plate-type AMM with an airborne sound excitation having different incident angles. The AMM is made of silicone rubber stubs squarely arranged in a thin aluminum plate, and the STL is calculated at low-frequency range [100Hz to 3kHz] for an incoming incident sound pressure wave. The obtained analytical and numerical STL present a very good agreement confirming the reliability of developed approaches. A comparison between computed STL and the band structure of the considered AMM shows an excellent agreement and gives a physical understanding of the observed behavior. On another hand, the acoustic energy confinement in AMM with created defects with suitable geometry was investigated. The first results give a general view for assessing the acoustic energy harvesting performances making use of AMM.

  7. Hybrid acoustic energy harvesting using combined electromagnetic and piezoelectric conversion.

    PubMed

    Khan, Farid Ullah; Izhar

    2016-02-01

    This paper reports a novel hybrid acoustic energy harvester. The harvester utilizes both the electromagnetic and piezoelectric conversion mechanisms simultaneously to convert the ambient acoustical noise into electrical power for self-powered wireless sensor nodes. The proposed harvester is comprised of a Helmholtz resonator, two magnets mounted on a piezoelectric plate, and a wound coil located under the magnets. The harvester is characterized both under harmonic and real random acoustical excitations. In-lab, under harmonic acoustical excitation at a sound pressure level of 130 dB and frequency of 2.1 kHz, an optimum power of 2.86 μW (at 114 Ω optimum load) is obtained from electromagnetic conversion and 50 μW (at 1000 Ω optimum load) is generated by the piezoelectric harvester's part. Moreover, in real acoustical environment of a domestic electric generator the peak voltages of 40 and 123 mV are produced by the electromagnetic and piezoelectric portions of the acoustic energy harvester. PMID:26931884

  8. Hybrid acoustic energy harvesting using combined electromagnetic and piezoelectric conversion

    NASA Astrophysics Data System (ADS)

    Khan, Farid Ullah; Izhar

    2016-02-01

    This paper reports a novel hybrid acoustic energy harvester. The harvester utilizes both the electromagnetic and piezoelectric conversion mechanisms simultaneously to convert the ambient acoustical noise into electrical power for self-powered wireless sensor nodes. The proposed harvester is comprised of a Helmholtz resonator, two magnets mounted on a piezoelectric plate, and a wound coil located under the magnets. The harvester is characterized both under harmonic and real random acoustical excitations. In-lab, under harmonic acoustical excitation at a sound pressure level of 130 dB and frequency of 2.1 kHz, an optimum power of 2.86 μW (at 114 Ω optimum load) is obtained from electromagnetic conversion and 50 μW (at 1000 Ω optimum load) is generated by the piezoelectric harvester's part. Moreover, in real acoustical environment of a domestic electric generator the peak voltages of 40 and 123 mV are produced by the electromagnetic and piezoelectric portions of the acoustic energy harvester.

  9. On the relationship between acoustic energy density flux near the jet and far field acoustic intensity

    NASA Technical Reports Server (NTRS)

    Maestrello, L.

    1973-01-01

    The relationship between the distribution of the outflow of acoustic energy over the jet boundary and the far-field directivity and intensity distribution is established by measurement and analysis. The numerical and experimental procedures involved have been checked out by using a known source. The results indicate that the acoustic power output per unit length of the jet, in the region from which the sound emanates, peaks at approximately 9 diameters downstream. The acoustic emission for a jet Strouhal number of about 0.3 exceeds the emission for all other Strouhal numbers nearly everywhere along the measurement plane. However, the far-field peak intensity distribution obtained from the contribution of each station was found to depend on the spatial extent of the region where sound emanates from the jet, which, in turn, depends more on the far-field angle than on the Strouhal number. The implications of these results for sound suppression techniques are discussed.

  10. Resting-Associated Vocalization Emitted by Captive Asian House Shrews (Suncus murinus): Acoustic Structure and Variability in an Unusual Mammalian Vocalization

    PubMed Central

    Schneiderová, Irena; Zouhar, Jan

    2014-01-01

    Shrews have rich vocal repertoires that include vocalizations within the human audible frequency range and ultrasonic vocalizations. Here, we recorded and analyzed in detail the acoustic structure of a vocalization with unclear functional significance that was spontaneously produced by 15 adult, captive Asian house shrews (Suncus murinus) while they were lying motionless and resting in their nests. This vocalization was usually emitted repeatedly in a long series with regular intervals. It showed some structural variability; however, the shrews most frequently emitted a tonal, low-frequency vocalization with minimal frequency modulation and a low, non-vocal click that was clearly noticeable at its beginning. There was no effect of sex, but the acoustic structure of the analyzed vocalizations differed significantly between individual shrews. The encoded individuality was low, but it cannot be excluded that this individuality would allow discrimination of family members, i.e., a male and female with their young, collectively resting in a common nest. The question remains whether the Asian house shrews indeed perceive the presence of their mates, parents or young resting in a common nest via the resting-associated vocalization and whether they use it to discriminate among their family members. Additional studies are needed to explain the possible functional significance of resting-associated vocalizations emitted by captive Asian house shrews. Our study highlights that the acoustic communication of shrews is a relatively understudied topic, particularly considering that they are highly vocal mammals. PMID:25390304

  11. Baryon Acoustic Oscillation Intensity Mapping of Dark Energy

    NASA Astrophysics Data System (ADS)

    Chang, Tzu-Ching; Pen, Ue-Li; Peterson, Jeffrey B.; McDonald, Patrick

    2008-03-01

    The expansion of the Universe appears to be accelerating, and the mysterious antigravity agent of this acceleration has been called “dark energy.” To measure the dynamics of dark energy, baryon acoustic oscillations (BAO) can be used. Previous discussions of the BAO dark energy test have focused on direct measurements of redshifts of as many as 109 individual galaxies, by observing the 21 cm line or by detecting optical emission. Here we show how the study of acoustic oscillation in the 21 cm brightness can be accomplished by economical three-dimensional intensity mapping. If our estimates gain acceptance they may be the starting point for a new class of dark energy experiments dedicated to large angular scale mapping of the radio sky, shedding light on dark energy.

  12. Baryon acoustic oscillation intensity mapping of dark energy.

    PubMed

    Chang, Tzu-Ching; Pen, Ue-Li; Peterson, Jeffrey B; McDonald, Patrick

    2008-03-01

    The expansion of the Universe appears to be accelerating, and the mysterious antigravity agent of this acceleration has been called "dark energy." To measure the dynamics of dark energy, baryon acoustic oscillations (BAO) can be used. Previous discussions of the BAO dark energy test have focused on direct measurements of redshifts of as many as 10(9) individual galaxies, by observing the 21 cm line or by detecting optical emission. Here we show how the study of acoustic oscillation in the 21 cm brightness can be accomplished by economical three-dimensional intensity mapping. If our estimates gain acceptance they may be the starting point for a new class of dark energy experiments dedicated to large angular scale mapping of the radio sky, shedding light on dark energy. PMID:18352692

  13. Enhanced performances for top-emitting white organic light-emitting diodes by utilizing green phosphor as energy transfer medium

    NASA Astrophysics Data System (ADS)

    Deng, Lingling; Bao, Yiyang; Zhang, Yanan; Peng, Ling; Zhu, Wenjing; Zhao, Yue; Xu, Yewen; Chen, Shufen

    2016-06-01

    In top-emitting white organic light-emitting diodes (TWOLEDs), the device performances attribute to the several important factors, such as exciton profile, energy transfer, and microcavity effect. In this paper, a TWOLED containing a heterojunction blue emission layer (EML) and a red EML is reported. A host material with high triplet energy level is employed for the adjacent blue and red EML, while the inefficient red emission reduces the emission efficiency of the TWOLED. In order to enhance the red emission efficiency, mixed-host and co-doping technologies are used in the red EML. By mixing the hole transporting and electron transporting host materials, the exciton recombination zone extends to the red EML to increase the red emission intensity and reduce the efficiency roll-off. And by co-doping a green phosphor into the red EML as the energy transfer medium, the energy transfer rate is enhanced, and then the current efficiency increases. Besides, both the mixed-host and co-doping change the carrier transport and the exciton recombination zone, which further affects the microcavity resonance in the devices. Due to the enhancement on the red emission intensity and the shift of resonant wavelength, the chromaticity of the TWOLED is improved.

  14. A comparative analysis of acoustic energy models for churches.

    PubMed

    Berardi, Umberto; Cirillo, Ettore; Martellotta, Francesco

    2009-10-01

    Different models to improve prediction of energy-based acoustic parameters in churches have been proposed by different researchers [E. Cirillo and F. Martellotta, J. Acoust. Soc. Am. 118, 232-248 (2005); T. Zamarreño et al., J. Acoust. Soc. Am. 121, 234-250 (2006)]. They all suggested variations to the "revised" theory proposed by Barron and Lee [J. Acoust. Soc. Am. 84, 618-628 (1988)], starting from experimental observations. The present paper compares these models and attempts to generalize their use taking advantage of the measurements carried out in 24 Italian churches differing in style, typology, and location. The whole sample of churches was divided into two groups. The first was used to fine-tune existing models, with particular reference to the "mu model," which was originally tested only on Mudejar-Gothic churches. Correlations between model parameters and major typological and architectural factors were found, leading to a classification that greatly simplifies parameter choice. Finally, the reliability of each model was verified on the rest of the sample, showing that acoustic parameters can be predicted with reasonable accuracy provided that one of the specifically modified theories is used. The results show that the model requiring more input parameters performs slightly better than the other which, conversely, is simpler to apply. PMID:19813798

  15. 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).

  16. Array of piezoelectric wires in acoustic energy harvesting

    NASA Astrophysics Data System (ADS)

    Golestanyan, Edvin

    An acoustic energy harvesting mechanism to harvest a travelling sound wave at a low audible frequency (180 ˜ 200Hz) is further developed and studied both experimentally and numerically. The acoustic energy harvester in this study consists of a quarter-wavelength straight tube resonator and multiple piezoelectric oscillators in wire and plate shapes placed inside the tube. When the tube resonator is excited by an incident sound at its acoustic resonant frequency, the amplified acoustic pressure inside the tube drives the vibration motions of piezoelectric oscillators, resulting in generating electricity. It has been found that a single piezoelectric plate generates more power than a wire, but with placing in multiple-rows piezoelectric wires more power is produced. Parallel and series connections of multiple piezoelectric oscillators have also been studied and expressions for calculating optimum loading resistance have been presented. It has been found that the series connection generates more power than parallel connection. As the number of piezoelectric oscillators increases, the magnitude of the single loading resistance decreases. The decrease of loading resistance is more intense in multiple wires than in multiple plates and in parallel connection than in series connection.

  17. Simulation chain for acoustic ultra-high energy neutrino detectors

    NASA Astrophysics Data System (ADS)

    Neff, M.; Anton, G.; Enzenhöfer, A.; Graf, K.; Hößl, J.; Katz, U.; Lahmann, R.

    2013-10-01

    Acoustic neutrino detection is a promising approach for large-scale ultra-high energy neutrino detectors in water. In this paper, a Monte Carlo simulation chain for acoustic neutrino detection devices in water is presented. It is designed within the SeaTray/IceTray software framework. Its modular architecture is highly flexible and makes it easy to adapt to different environmental conditions, detector geometries, and hardware. The simulation chain covers the generation of the acoustic pulse produced by a neutrino interaction and the propagation to the sensors within the detector. In this phase of the development, ambient and transient noise models for the Mediterranean Sea and simulations of the data acquisition hardware, similar to the one used in ANTARES/AMADEUS, are implemented. A pre-selection scheme for neutrino-like signals based on matched filtering is employed, as it can be used for on-line filtering. To simulate the whole processing chain for experimental data, signal classification and acoustic source reconstruction algorithms are integrated. In this contribution, an overview of the design and capabilities of the simulation chain will be given, and some applications and preliminary studies will be presented.

  18. A hydrophone prototype for ultra high energy neutrino acoustic detection

    NASA Astrophysics Data System (ADS)

    Cotrufo, A.; Plotnikov, A.; Yershova, O.; Anghinolfi, M.; Piombo, D.

    2009-06-01

    The design of an air-backed fiber-optic hydrophone is presented. With respect to the previous models this prototype is optimized to provide a bandwidth sufficiently large to detect acoustic signals produced by high energy hadronic showers in water. In addiction to the geometrical configuration and to the choice of the materials, the preliminary results of the measured performances in air are presented.

  19. 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.

  20. Device and method for generating a beam of acoustic energy from a borehole, and applications thereof

    SciTech Connect

    Vu, Cung Khac; Sinha, Dipen N; Pantea, Cristian; Nihei, Kurt T; Schmitt, Denis P; Skelt, Christopher

    2013-10-01

    In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed. The method includes generating a first acoustic wave at a first frequency; generating a second acoustic wave at a second frequency different than the first frequency, wherein the first acoustic wave and second acoustic wave are generated by at least one transducer carried by a tool located within the borehole; transmitting the first and the second acoustic waves into an acoustically non-linear medium, wherein the composition of the non-linear medium produces a collimated beam by a non-linear mixing of the first and second acoustic waves, wherein the collimated beam has a frequency based upon a difference between the first frequency and the second frequency; and transmitting the collimated beam through a diverging acoustic lens to compensate for a refractive effect caused by the curvature of the borehole.

  1. Nonlinear optimization of acoustic energy harvesting using piezoelectric devices.

    PubMed

    Lallart, Mickaeël; Guyomar, Daniel; Richard, Claude; Petit, Lionel

    2010-11-01

    In the first part of the paper, a single degree-of-freedom model of a vibrating membrane with piezoelectric inserts is introduced and is initially applied to the case when a plane wave is incident with frequency close to one of the resonance frequencies. The model is a prototype of a device which converts ambient acoustical energy to electrical energy with the use of piezoelectric devices. The paper then proposes an enhancement of the energy harvesting process using a nonlinear processing of the output voltage of piezoelectric actuators, and suggests that this improves the energy conversion and reduces the sensitivity to frequency drifts. A theoretical discussion is given for the electrical power that can be expected making use of various models. This and supporting experimental results suggest that a nonlinear optimization approach allows a gain of up to 10 in harvested energy and a doubling of the bandwidth. A model is introduced in the latter part of the paper for predicting the behavior of the energy-harvesting device with changes in acoustic frequency, this model taking into account the damping effect and the frequency changes introduced by the nonlinear processes in the device. PMID:21110569

  2. Treated cabin acoustic prediction using statistical energy analysis

    NASA Technical Reports Server (NTRS)

    Yoerkie, Charles A.; Ingraham, Steven T.; Moore, James A.

    1987-01-01

    The application of statistical energy analysis (SEA) to the modeling and design of helicopter cabin interior noise control treatment is demonstrated. The information presented here is obtained from work sponsored at NASA Langley for the development of analytic modeling techniques and the basic understanding of cabin noise. Utility and executive interior models are developed directly from existing S-76 aircraft designs. The relative importance of panel transmission loss (TL), acoustic leakage, and absorption to the control of cabin noise is shown using the SEA modeling parameters. It is shown that the major cabin noise improvement below 1000 Hz comes from increased panel TL, while above 1000 Hz it comes from reduced acoustic leakage and increased absorption in the cabin and overhead cavities.

  3. Enhanced output power by eigenfrequency shift in acoustic energy harvester

    NASA Astrophysics Data System (ADS)

    Li, Bin; You, Jeong Ho

    2014-04-01

    In our previous studies, multiple piezoelectric cantilever plates were placed inside a quarter-wavelength straight tube resonator to harvest low frequency acoustic energy. To investigate the modification of eigenmodes in the tube resonator due to the presence of piezoelectric plates, the eigenfrequency shift properties by introducing single and multiple rectangular blockages in open-closed ducts are studied by using 1D segmented Helmholtz equations, Webster horn equation, and finite element simulations. The first-mode eigenfrequency of the duct is reduced when the blockage is placed near the open inlet. The decrease of eigenfrequency leads to the enhancement of absorbed acoustic power in the duct. Furthermore, the first half of the tube resonator possesses high pressure gradient resulting in larger driving forces for the vibration motion of piezoelectric plates. Therefore, in our harvesters, it is better to place the piezoelectric plates in the first half of the tube resonator to obtain high output voltage and power.

  4. Acoustic metamaterials capable of both sound insulation and energy harvesting

    NASA Astrophysics Data System (ADS)

    Li, Junfei; Zhou, Xiaoming; Huang, Guoliang; Hu, Gengkai

    2016-04-01

    Membrane-type acoustic metamaterials are well known for low-frequency sound insulation. In this work, by introducing a flexible piezoelectric patch, we propose sound-insulation metamaterials with the ability of energy harvesting from sound waves. The dual functionality of the metamaterial device has been verified by experimental results, which show an over 20 dB sound transmission loss and a maximum energy conversion efficiency up to 15.3% simultaneously. This novel property makes the metamaterial device more suitable for noise control applications.

  5. Diffusive Propagation of Energy in a Non-acoustic Chain

    NASA Astrophysics Data System (ADS)

    Komorowski, Tomasz; Olla, Stefano

    2016-08-01

    We consider a non-acoustic chain of harmonic oscillators with the dynamics perturbed by a random local exchange of momentum, such that energy and momentum are conserved. The macroscopic limits of the energy density, momentum and the curvature (or bending) of the chain satisfy a system of evolution equations. We prove that, in a diffusive space-time scaling, the curvature and momentum evolve following a linear system that corresponds to a damped Euc(uler)-Buc(ernoulli) beam equation. The macroscopic energy density evolves following a non linear diffusive equation. In particular, the energy transfer is diffusive in this dynamics. This provides a first rigorous example of a normal diffusion of energy in a one dimensional dynamics that conserves the momentum.

  6. Considerations on the acoustic energy radiated by toothed gears. [model for calculating noise intensity

    NASA Technical Reports Server (NTRS)

    Popinceanu, N. G.; Kremmer, I.

    1974-01-01

    A mechano-acoustic model is reported for calculating acoustic energy radiated by a working gear. According to this model, a gear is an acoustic coublet formed of the two wheels. The wheel teeth generate cylindrical acoustic waves while the front surfaces of the teeth behave like vibrating pistons. Theoretical results are checked experimentally and good agreement is obtained with open gears. The experiments show that the air noise effect is negligible as compared with the structural noise transmitted to the gear box.

  7. Evaluation of photo-acoustic infrared multigas analyzer in measuring concentrations of greenhouse gases emitted from feedlot soil/manure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Photo-acoustic infrared multigas analyzers (PIMAs) are being increasingly utilized to measure concentrations and fluxes of greenhouse gases (i.e., N2O, CO2, and CH4) at the soil surface because of their low cost, portability, and ease of operation. This research evaluated a PIMA in combination with ...

  8. Device and method for generating a beam of acoustic energy from a borehole, and applications thereof

    DOEpatents

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian; Nihei, Kurt T.; Schmitt, Denis P.; Skelt, Chirstopher

    2013-10-15

    In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed. The method includes generating a first acoustic wave at a first frequency; generating a second acoustic wave at a second frequency different than the first frequency, wherein the first acoustic wave and second acoustic wave are generated by at least one transducer carried by a tool located within the borehole; transmitting the first and the second acoustic waves into an acoustically non-linear medium, wherein the composition of the non-linear medium produces a collimated beam by a non-linear mixing of the first and second acoustic waves, wherein the collimated beam has a frequency based upon a difference between the first frequency range and the second frequency, and wherein the non-linear medium has a velocity of sound between 100 m/s and 800 m/s.

  9. Search for acoustic signals from high energy cascades

    NASA Technical Reports Server (NTRS)

    Bell, R.; Bowen, T.

    1985-01-01

    High energy cosmic ray secondaries can be detected by means of the cascades they produce when they pass through matter. When the charged particles of these cascades ionize the matter they are traveling through, the heat produced and resulting thermal expansion causes a thermoacoustic wave. These sound waves travel at about one hundred-thousandth the speed of light, and should allow an array of acoustic transducers to resolve structure in the cascade to about 1 cm without high speed electronics or segmentation of the detector.

  10. Helmholtz Resonator for Lead Zirconate Titanate Acoustic Energy Harvester

    NASA Astrophysics Data System (ADS)

    Matsuda, Tomohiro; Tomii, Kazuki; Hagiwara, Saori; Miyake, Shuntaro; Hasegawa, Yuichi; Sato, Takamitsu; Kaneko, Yuta; Nishioka, Yasushiro

    2013-12-01

    Acoustic energy harvesters that function in environments where sound pressure is extremely high (~150 dB), such as in engine rooms of aircrafts, are expected to be capable of powering wireless health monitoring systems. This paper presents the power generation performances of a lead-zirconate-titanate (PZT) acoustic energy harvester with a vibrating PZT diaphragm. The diaphragm had a diameter of 2 mm, consisting of Al(0.1 μm)/PZT(1 μm)/Pt(0.1 μm)/Ti(0.1 μm)/SiO2(1.5 μm). The harvester generated a power of 1.7×10-13 W under a sound pressure level of 110 dB at the first resonance frequency of 6.28 kHz. It was found that the generated power was increased to 6.8×10-13 W using a sound-collecting Helmholtz resonator cone with the height of 60 mm. The cone provided a Helmholtz resonance at 5.8 kHz, and the generated power increased from 3.4×10-14 W to 1.4×10-13 W at this frequency. The cone was also effective in increasing the bandwidth of the energy harvester.

  11. Energy spectrum of argon ions emitted from Filippov type Sahand plasma focus

    SciTech Connect

    Mohammadnejad, M.; Pestehe, S. J.; Mohammadi, M. A.

    2013-07-15

    The energy and flux of the argon ions produced in Sahand plasma focus have been measured by employing a well-designed Faraday cup. The secondary electron emission effects on the ion signals are simulated and the dimensions of Faraday cup are optimized to minimize these effects. The measured ion energy spectrum is corrected for the ion energy loss and charge exchange in the background gas. The effects of the capacitor bank voltage and working gas pressure on the ion energy spectrum are also investigated. It has been shown that the emitted ion number per energy increases as the capacitor bank voltage increases. Decreasing the working gas pressure leads to the increase in the number of emitted ion per energy.

  12. A radio view of high-energy emitting AGNs

    NASA Astrophysics Data System (ADS)

    Schulz, Robert Frank

    2016-07-01

    Active galactic nuclei (AGNs) are among the most energetic objects in the Universe. These galaxies that are dominated in part or even throughout the electromagnetic spectrum by emission from their central, compact region. AGNs are extensively studied by multi-wavelength observations. In the standard picture, the main driver of an AGN is a supermassive black hole (SMBH) in its centre that is surrounded by an accretion disk. Perpendicular to the disk, in the vicinity of highly magnetized SMBH relativistic outflows of plasma, so-called jets, can form on either side that can reach far beyond the host galaxy. Only about 10% of all AGNs are dominated by emission from these jets due to relativistic beaming effects and these so-called blazars dominate the extragalactic gamma-ray sky. It is commonly accepted that the low-energy emission (radio to UV/X-ray) is due to synchrotron emission from the jet. The high-energy emission is considered to stem from inverse-Compton scattering of photons on the jet particles, but different sources for these photons are discussed (internal or external to the AGN) and other models for the high-energy emission have also been proposed. The nature of the high-energy emission is strongly linked to the location of the emission region in the jet which requires a detailed understanding of the formation and evolution of jets. Radio observations especially using very long baseline interferometry (VLBI) provide the best way to gain direct information on the intrinsic properties of jets down to sub-pc scales, close to their formation region. In this thesis, I focus on the properties of three different AGNs, IC 310, PKS2004-447, and 3C 111 that belong to the small non-blazar population of gamma-ray-loud AGNs. I study them in detail with a variety of radio astronomical instruments with respect to their high-energy emission and in the context of the large monitoring programmes MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) and

  13. A wideband acoustic energy harvester using a three degree-of-freedom architecture

    NASA Astrophysics Data System (ADS)

    Peng, Xiao; Wen, Yumei; Li, Ping; Yang, Aichao; Bai, Xiaoling

    2013-10-01

    In this study, an acoustic energy harvester consisting of a perforated brass plate sandwiched between two cavities is designed and fabricated for scavenging energy from wide-spectrum acoustic sources. The multi-mode resonances of the device are adjusted closely spaced over a wide range of frequencies by properly tuned acoustic coupling of the vibrating plate and the two cavities. The experimental results show that the proximity of the multiple peaks enables the harvester operating in the frequency range of 1100-1400 Hz, which provides useful leads for the realization of acoustic energy generators of practical interest.

  14. Energy-based dosimetry of low-energy, photon-emitting brachytherapy sources

    NASA Astrophysics Data System (ADS)

    Malin, Martha J.

    Model-based dose calculation algorithms (MBDCAs) for low-energy, photon-emitting brachytherapy sources have advanced to the point where the algorithms may be used in clinical practice. Before these algorithms can be used, a methodology must be established to verify the accuracy of the source models used by the algorithms. Additionally, the source strength metric for these algorithms must be established. This work explored the feasibility of verifying the source models used by MBDCAs by measuring the differential photon fluence emitted from the encapsulation of the source. The measured fluence could be compared to that modeled by the algorithm to validate the source model. This work examined how the differential photon fluence varied with position and angle of emission from the source, and the resolution that these measurements would require for dose computations to be accurate to within 1.5%. Both the spatial and angular resolution requirements were determined. The techniques used to determine the resolution required for measurements of the differential photon fluence were applied to determine why dose-rate constants determined using a spectroscopic technique disagreed with those computed using Monte Carlo techniques. The discrepancy between the two techniques had been previously published, but the cause of the discrepancy was not known. This work determined the impact that some of the assumptions used by the spectroscopic technique had on the accuracy of the calculation. The assumption of isotropic emission was found to cause the largest discrepancy in the spectroscopic dose-rate constant. Finally, this work improved the instrumentation used to measure the rate at which energy leaves the encapsulation of a brachytherapy source. This quantity is called emitted power (EP), and is presented as a possible source strength metric for MBDCAs. A calorimeter that measured EP was designed and built. The theoretical framework that the calorimeter relied upon to measure EP

  15. 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.

  16. Generalization and extension of the law of acoustic energy conservation in a nonuniform flow

    NASA Technical Reports Server (NTRS)

    Myers, M. K.

    1986-01-01

    An exact conservation equation is derived which generalizes the familiar acoustic energy equations. The new relation is valid for arbitrary disturbances to a viscous, compressible flow. It is suggested by a development of the acoustic energy equation by means of a regular perturbation expansion of the general energy equation of fluid mechanics. A perturbation energy density and flux are defined and identified as the exact physical quantities whose leading order perturbation representations are the usual acoustic energy density and flux. The conservation equation governing the perturbation energy quantities is shown to yield previously known results for several special cases.

  17. Broadband energy harvesting using acoustic black hole structural tailoring

    NASA Astrophysics Data System (ADS)

    Zhao, Liuxian; Conlon, Stephen C.; Semperlotti, Fabio

    2014-06-01

    This paper explores the concept of an acoustic black hole (ABH) as a main design framework for performing dynamic structural tailoring of mechanical systems for vibration energy harvesting applications. The ABH is an integral feature embedded in the host structure that allows for a smooth reduction of the phase velocity, theoretically approaching zero, while minimizing the reflected energy. This mechanism results in structural areas with high energy density that can be effectively exploited to develop enhanced vibration-based energy harvesting. Fully coupled electro-mechanical models of an ABH tapered structure with surface mounted piezo-transducers are developed to numerically simulate the response of the system to both steady state and transient excitations. The design performances are numerically evaluated using structural intensity data as well as the instantaneous voltage/power and energy output produced by the piezo-transducer network. Results show that the dynamically tailored structural design enables a drastic increase in the harvested energy as compared to traditional structures, both under steady state and transient excitation conditions.

  18. Enhanced vibration based energy harvesting using embedded acoustic black holes

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Semperlotti, F.; Conlon, S. C.

    2014-03-01

    In this paper, we investigate the use of dynamic structural tailoring via the concept of an Acoustic Black Hole (ABH) to enhance the performance of piezoelectric based energy harvesting from operational mechanical vibrations. The ABH is a variable thickness structural feature that can be embedded in the host structure allowing a smooth reduction of the phase velocity while minimizing the amplitude of reflected waves. The ABH thickness variation is typically designed according to power-law profiles. As a propagating wave enters the ABH, it is progressively slowed down while its wavelength is compressed. This effect results in structural areas with high energy density that can be exploited effectively for energy harvesting. The potential of ABH for energy harvesting is shown via a numerical study based on fully coupled finite element electromechanical models of an ABH tapered plate with surface mounted piezo-transducers. The performances of the novel design are evaluated by direct comparison with a non-tapered structure in terms of energy ratios and attenuation indices. Results show that the tailored structural design allows a drastic increase in the harvested energy both for steady state and transient excitation. Performance dependencies of key design parameters are also investigated.

  19. High-energy terahertz wave parametric oscillator with a surface-emitted ring-cavity configuration.

    PubMed

    Yang, Zhen; Wang, Yuye; Xu, Degang; Xu, Wentao; Duan, Pan; Yan, Chao; Tang, Longhuang; Yao, Jianquan

    2016-05-15

    A surface-emitted ring-cavity terahertz (THz) wave parametric oscillator has been demonstrated for high-energy THz output and fast frequency tuning in a wide frequency range. Through the special optical design with a galvano-optical scanner and four-mirror ring-cavity structure, the maximum THz wave output energy of 12.9 μJ/pulse is achieved at 1.359 THz under the pump energy of 172.8 mJ. The fast THz frequency tuning in the range of 0.7-2.8 THz can be accessed with the step response of 600 μs. Moreover, the maximum THz wave output energy from this configuration is 3.29 times as large as that obtained from the conventional surface-emitted THz wave parametric oscillator with the same experimental conditions. PMID:27176978

  20. Acoustic energy relations in Mudejar-Gothic churches.

    PubMed

    Zamarreño, Teófilo; Girón, Sara; Galindo, Miguel

    2007-01-01

    Extensive objective energy-based parameters have been measured in 12 Mudejar-Gothic churches in the south of Spain. Measurements took place in unoccupied churches according to the ISO-3382 standard. Monoaural objective measures in the 125-4000 Hz frequency range and in their spatial distributions were obtained. Acoustic parameters: clarity C80, definition D50, sound strength G and center time Ts have been deduced using impulse response analysis through a maximum length sequence measurement system in each church. These parameters spectrally averaged according to the most extended criteria in auditoria in order to consider acoustic quality were studied as a function of source-receiver distance. The experimental results were compared with predictions given by classical and other existing theoretical models proposed for concert halls and churches. An analytical semi-empirical model based on the measured values of the C80 parameter is proposed in this work for these spaces. The good agreement between predicted values and experimental data for definition, sound strength, and center time in the churches analyzed shows that the model can be used for design predictions and other purposes with reasonable accuracy. PMID:17297779

  1. High Energy Terahertz Parametric Oscillator Based on Surface-Emitted Configuration

    NASA Astrophysics Data System (ADS)

    Xu, De-Gang; Zhang, Hao; Jiang, Hao; Wang, Yu-Ye; Liu, Chang-Ming; Yu, Hong; Li, Zhong-Yang; Shi, Wei; Yao, Jian-Quan

    2013-02-01

    We experimentally demonstrate a high power nanosecond pulsed terahertz (THz)-wave parametric oscillator (TPO) by using a wide pump beam. A surface emitted cavity configuration is employed to reduce the THz absorption in MgO:LiNbO3 crystal. The THz wave can be tuned from 1 THz to 3 THz. A maximum THz output energy of 438 nJ/pulse is achieved at 1.56 Hz using a 4.5-mm-diameter pump beam with a pulse energy of 226 mJ pump energy with the repetition of 10 Hz, corresponding to the energy conversion efficiency of 1.94 × 10-6.

  2. Energy Correlation among Three Photoelectrons Emitted in Core-Valence-Valence Triple Photoionization of Ne

    SciTech Connect

    Hikosaka, Y.; Soejima, K.; Lablanquie, P.; Penent, F.; Palaudoux, J.; Andric, L.; Shigemasa, E.; Suzuki, I. H.; Nakano, M.; Ito, K.

    2011-09-09

    The direct observation of triple photoionization involving one inner shell and two valence electrons is reported. The energy distribution of the three photoelectrons emitted from Ne is obtained using a very efficient multielectron coincidence method using the magnetic bottle electron spectroscopic technique. A predominance of the direct path to triple photoionization for the formation of Ne{sup 3+} in the 1s2s{sup 2}2p{sup 4} configuration is observed. It is demonstrated that the energy distribution evolves with photon energy and indicates a significant difference with triple photoionization involving only valence electrons.

  3. Energy Correlation among Three Photoelectrons Emitted in Core-Valence-Valence Triple Photoionization of Ne

    NASA Astrophysics Data System (ADS)

    Hikosaka, Y.; Lablanquie, P.; Penent, F.; Palaudoux, J.; Andric, L.; Soejima, K.; Shigemasa, E.; Suzuki, I. H.; Nakano, M.; Ito, K.

    2011-09-01

    The direct observation of triple photoionization involving one inner shell and two valence electrons is reported. The energy distribution of the three photoelectrons emitted from Ne is obtained using a very efficient multielectron coincidence method using the magnetic bottle electron spectroscopic technique. A predominance of the direct path to triple photoionization for the formation of Ne3+ in the 1s2s22p4 configuration is observed. It is demonstrated that the energy distribution evolves with photon energy and indicates a significant difference with triple photoionization involving only valence electrons.

  4. Energy correlation among three photoelectrons emitted in core-valence-valence triple photoionization of Ne.

    PubMed

    Hikosaka, Y; Lablanquie, P; Penent, F; Palaudoux, J; Andric, L; Soejima, K; Shigemasa, E; Suzuki, I H; Nakano, M; Ito, K

    2011-09-01

    The direct observation of triple photoionization involving one inner shell and two valence electrons is reported. The energy distribution of the three photoelectrons emitted from Ne is obtained using a very efficient multielectron coincidence method using the magnetic bottle electron spectroscopic technique. A predominance of the direct path to triple photoionization for the formation of Ne3+ in the 1s 2s2 2p4 configuration is observed. It is demonstrated that the energy distribution evolves with photon energy and indicates a significant difference with triple photoionization involving only valence electrons. PMID:22026663

  5. A new absolute method for the standardization of radionuclides emitting low-energy radiation.

    PubMed

    Leblanc, E; de, Marcillac P; Coron, N; Leblanc, J; Loidl, M; Metge, J F; Bouchard, J

    2002-01-01

    Microcalorimeters (or bolometers) operated at temperatures below 100 mK allow individual counting of photons and electrons with a very low energy detection threshold. The physics is based on the pulse temperature increase of the target (or absorber) of the detector due to the complete absorption of both electrons and photons. Since this target can be constructed with a perfect 4-pi geometry, a bolometer offers potentially a new method for absolute activity measurements of radionuclides emitting low-energy radiation. In this paper we present our first results of a feasibility study of activity standardization of a 55Fe solution with a prototype 4-pi bolometer. PMID:11839023

  6. Electrical and optical measurements of the bandgap energy of a light-emitting diode

    NASA Astrophysics Data System (ADS)

    Petit, Matthieu; Michez, Lisa; Raimundo, Jean-Manuel; Dumas, Philippe

    2016-03-01

    Semiconductor materials are at the core of electronics. Most electronic devices are made of semiconductors. The operation of these components is well described by quantum physics which is often a difficult concept for students to understand. One of the intrinsic parameters of semiconductors is their bandgap energy {{E}\\text{g}} . In the case of light-emitting diodes (LEDs) {{E}\\text{g}} fixes the colour of the light emitted by the diodes. In this article we propose an experiment to compare {{E}\\text{g}} of a green LED obtained by both electrical and optical measurements. The two slightly different results can be explained by the theoretical knowledge of students on solid physics and the internal structure of electronic devices.

  7. White organic light-emitting diodes based on incomplete energy transfer from perylene to rubrene

    NASA Astrophysics Data System (ADS)

    Ding, Bangdong; Zhu, Wenqing; Jiang, Xueyin; Zhang, Zhilin

    2008-11-01

    This paper presents organic light-emitting diodes which generate white emission based on both perylene and rubrene doped in 9,10-di(2-naphthyl)anthracene (ADN). In this doping system, the blue dopant perylene not only emitted but also assisted the energy transfer from ADN to rubrene, which contributes to a lower doping concentration of rubrene. The optimal configuration of the device is ITO/TPD(50 nm)/ADN:0.5 wt% perylene:0.006 wt% rubrene(40 nm)/Bphen(25 nm)/LiF(1 nm)/Al. The maximum luminance of 11 665 cd/m 2 at 14 V according to a luminance efficiency of 2.9 cd/A was obtained. A CIE color coordinate of (0.30, 0.37) at 4 mA/cm 2 was also achieved.

  8. Wavelength-stable rare earth-free green light-emitting diodes for energy efficiency.

    PubMed

    Wetzel, Christian; Detchprohm, Theeradetch

    2011-07-01

    Solid state lighting seeks to replace both, incandescent and fluorescent lighting by energy efficient light-emitting diodes (LEDs). Just like compact fluorescent tubes, current white LEDs employ costly rare earth-based phosphors, a drawback we propose to overcome with direct emitting LEDs of all colors. We show the benefits of homoepitaxial LEDs on bulk GaN substrate for wavelength-stable green spectrum LEDs. By use of non-polar growth orientation we avoid big color shifts with drive current and demonstrate polarized light emitters that prove ideal for pairing with liquid crystal display modulators in back light units of television monitors. We further offer a comparison of the prospects of non-polar a- and m-plane growth over conventional c-plane growth. PMID:21747568

  9. 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.

  10. 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.

  11. A Correlated Study of the Response of a Satellite to Acoustic Radiation Using Statistical Energy Analysis and Acoustic Test Data

    SciTech Connect

    CAP,JEROME S.; TRACEY,BRIAN

    1999-11-15

    Aerospace payloads, such as satellites, are subjected to vibroacoustic excitation during launch. Sandia's MTI satellite has recently been certified to this environment using a combination of base input random vibration and reverberant acoustic noise. The initial choices for the acoustic and random vibration test specifications were obtained from the launch vehicle Interface Control Document (ICD). In order to tailor the random vibration levels for the laboratory certification testing, it was necessary to determine whether vibration energy was flowing across the launch vehicle interface from the satellite to the launch vehicle or the other direction. For frequencies below 120 Hz this issue was addressed using response limiting techniques based on results from the Coupled Loads Analysis (CLA). However, since the CLA Finite Element Analysis FEA model was only correlated for frequencies below 120 Hz, Statistical Energy Analysis (SEA) was considered to be a better choice for predicting the direction of the energy flow for frequencies above 120 Hz. The existing SEA model of the launch vehicle had been developed using the VibroAcoustic Payload Environment Prediction System (VAPEPS) computer code [1]. Therefore, the satellite would have to be modeled using VAPEPS as well. As is the case for any computational model, the confidence in its predictive capability increases if one can correlate a sample prediction against experimental data. Fortunately, Sandia had the ideal data set for correlating an SEA model of the MTI satellite--the measured response of a realistic assembly to a reverberant acoustic test that was performed during MTI's qualification test series. The first part of this paper will briefly describe the VAPEPS modeling effort and present the results of the correlation study for the VAPEPS model. The second part of this paper will present the results from a study that used a commercial SEA software package [2] to study the effects of in-plane modes and to

  12. 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.

  13. Energy analysis during acoustic bubble oscillations: relationship between bubble energy and sonochemical parameters.

    PubMed

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

    2014-01-01

    In this work, energy analysis of an oscillating isolated spherical bubble in water irradiated by an ultrasonic wave has been theoretically studied for various conditions of acoustic amplitude, ultrasound frequency, static pressure and liquid temperature in order to explain the effects of these key parameters on both sonochemistry and sonoluminescence. The Keller-Miksis equation for the temporal variation of the bubble radius in compressible and viscous medium has been employed as a dynamics model. The numerical calculations showed that the rate of energy accumulation, dE/dt, increased linearly with increasing acoustic amplitude in the range of 1.5-3.0 atm and decreased sharply with increasing frequency in the range 200-1000 kHz. There exists an optimal static pressure at which the power w is highest. This optimum shifts toward a higher value as the acoustic amplitude increases. The energy of the bubble slightly increases with the increase in liquid temperature from 10 to 60 °C. The results of this study should be a helpful means to explain a variety of experimental observations conducted in the field of sonochemistry and sonoluminescence concerning the effects of operational parameters. PMID:23683796

  14. Acoustic Energy: An Innovative Technology for Stimulating Oil Wells

    SciTech Connect

    Edgar, Dorland E.; Peters, Robert W.; Johnson, Donald O.; Paulsen, P. David; Roberts, Wayne

    2006-04-30

    The objective of this investigation was to demonstrate the effectiveness of sonication in reducing the viscosity of heavy crude oils. Sonication is the use of acoustic or sound energy to produce physical and/or chemical changes in materials, usually fluids. The goal of the first project phase was to demonstrate a proof of concept for the project objective. Batch tests of three commercially available, single-weight oils (30-, 90-, and 120-wt) were performed in the laboratory. Several observations and conclusions were made from this series of experiments. These include the following: (1) In general, the lower the acoustic frequency, the greater the efficiency in reducing the viscosity of the oils; (2) Sonication treatment of the three oils resulted in reductions in viscosity that ranged from a low of 31% to a high of 75%; and (3) The results of the first phase of the project successfully demonstrated that sonication could reduce the viscosity of oils of differing viscosity. The goal of the second project phase was to demonstrate the ability of sonication to reduce the viscosity of three crude oils ranging from a light crude to a heavy crude. The experiments also were designed to examine the benefits of two proprietary chemical additives used in conjunction with sonication. Acoustic frequencies ranging from 800 Hz to 1.6 kHz were used in these tests, and a reactor chamber was designed for flow-through operation with a capacity of one gallon (3.8 liters). The three crude oils selected for use in the testing program were: (1) a heavy crude from California with a viscosity of approximately 65,000 cP (API gravity about 12{sup o}), (2) a crude from Alabama with a significant water content and a viscosity of approximately 6,000 cP (API gravity about 22 {sup o}), and (3) a light crude from the Middle East with a viscosity of approximately 700 cP (API gravity about 32{sup o}). The principal conclusions derived from the second project phase include the following: (1) The

  15. Effect of static pressure on acoustic energy radiated by cavitation bubbles in viscous liquids under ultrasound.

    PubMed

    Yasui, Kyuichi; Towata, Atsuya; Tuziuti, Toru; Kozuka, Teruyuki; Kato, Kazumi

    2011-11-01

    The effect of static pressure on acoustic emissions including shock-wave emissions from cavitation bubbles in viscous liquids under ultrasound has been studied by numerical simulations in order to investigate the effect of static pressure on dispersion of nano-particles in liquids by ultrasound. The results of the numerical simulations for bubbles of 5 μm in equilibrium radius at 20 kHz have indicated that the optimal static pressure which maximizes the energy of acoustic waves radiated by a bubble per acoustic cycle increases as the acoustic pressure amplitude increases or the viscosity of the solution decreases. It qualitatively agrees with the experimental results by Sauter et al. [Ultrason. Sonochem. 15, 517 (2008)]. In liquids with relatively high viscosity (∼200 mPa s), a bubble collapses more violently than in pure water when the acoustic pressure amplitude is relatively large (∼20 bar). In a mixture of bubbles of different equilibrium radius (3 and 5 μm), the acoustic energy radiated by a 5 μm bubble is much larger than that by a 3 μm bubble due to the interaction with bubbles of different equilibrium radius. The acoustic energy radiated by a 5 μm bubble is substantially increased by the interaction with 3 μm bubbles. PMID:22087995

  16. Device and method for generating a beam of acoustic energy from a borehole, and applications thereof

    DOEpatents

    Vu, Cung Khac; Sinha, Dipen N; Pantea, Cristian; Nihei, Kurt T; Schmitt, Denis P; Skelt, Christopher

    2013-10-01

    In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed. The method includes generating a first broad-band acoustic pulse at a first broad-band frequency range having a first central frequency and a first bandwidth spread; generating a second broad-band acoustic pulse at a second broad-band frequency range different than the first frequency range having a second central frequency and a second bandwidth spread, wherein the first acoustic pulse and second acoustic pulse are generated by at least one transducer arranged on a tool located within the borehole; and transmitting the first and the second broad-band acoustic pulses into an acoustically non-linear medium, wherein the composition of the non-linear medium produces a collimated pulse by a non-linear mixing of the first and second acoustic pulses, wherein the collimated pulse has a frequency equal to the difference in frequencies between the first central frequency and the second central frequency and a bandwidth spread equal to the sum of the first bandwidth spread and the second bandwidth spread.

  17. Energy level alignment at the interfaces in a multilayer organic light-emitting diode structure

    NASA Astrophysics Data System (ADS)

    Olthof, S.; Meerheim, R.; Schober, M.; Leo, K.

    2009-06-01

    We use photoelectron spectroscopy to study the electronic structure and energy level alignment throughout an organic light-emitting diode. The structure under investigation is a state-of-the-art long-living red phosphorescent device composed of doped charge-injection layers, charge-blocking layers, and an emission layer. By consecutively building up the whole device, the key parameters of every interface are measured. Our results show that the doped layers have a significant influence on the device energetics, especially in controlling the built-in potential, and that there are mostly only small dipoles present at the interfaces of the intrinsic organic layers.

  18. Red organic light-emitting diodes based on wide band gap emitting material as the host utilizing two-step energy transfer

    NASA Astrophysics Data System (ADS)

    Haq, Khizar-ul; Shan-peng, Liu; Khan, M. A.; Jiang, X. Y.; Zhang, Z. L.; Zhu, W. Q.

    2008-03-01

    We demonstrated efficient red organic light-emitting diodes based on a host emitting system of 9,10-di(2-naphthyl)anthracene (ADN) co-doped with 4-(dicyano-methylene)-2-t-butyle-6- (1,1,7,7-tetramethyl-julolidyl-9-enyl)-4H-pyran (DCJTB) as a red dopant and 2,3,6,7- tetrahydro-1,1,7,7-tetramethyl-1H,5H,1 1H-10(2-benzothiazolyl)-quinolizine-[9,9a,1gh] coumarin (C545T) as an assistant dopant. The typical device structure was glass substrate/ITO/4,4',4''-tris(N-3-methylphenyl-N-phenylamino) triphenylamine(m-MTDATA)/N,N'-bis-(naphthalene-1-yl)-N,N'-diphenylbenzidine(NPB)/[ADN: DCJTB: C545T/Alq3/LiF/Al]. It was found that C545T dopant did not emit by itself but did assist the energy transfer from the host (ADN) to the red emitting dopant. The red OLEDs realized by this approach not only enhanced the emission color, but also significantly improved the EL efficiency. The EL efficiency reached 3.5 cd A-1 at a current density of 20 mA cm-2, which is enhanced by three times compared with devices where the emissive layer is composed of the DCJTB doped ADN. The saturated red emission was obtained with CIE coordinates (x = 0.618, y = 0.373) at 621 nm, and the device driving voltage is decreased as much as 38%. We attribute these improvements to the assistant dopant (C545T), which leads to the more efficient energy transfer from ADN to DCJTB. These results indicate that the co-doped system is a promising method for obtaining high-efficiency red OLEDs.

  19. Effects of atmosphere, temperature and emittance on reflected and emitted energy

    NASA Technical Reports Server (NTRS)

    Kumar, R.

    1977-01-01

    The effects of temperature and emittance on the relative magnitude of reflected energy and emitter energy from a target including atmospheric effects was studied. From the calculations of energy reflected and emitted from a target including atmospheric effects using LOWTRAN 3 programs for midlatitude summer model, the following conclusions were obtained: (1) At 3.5 micrometers q is considerably less than 1 except at high temperatures and for high emittance; (2) at 4 micrometers q is of the order of magnitude equal to 1 for most targets; and (3) at 4.6 micrometers, q is considerably greater than 1 at high temperatures and high emittance. In addition, incident atmospheric emission reflected from the target was found to be negligible except for targets having low temperature and low emittance.

  20. An analysis of the acoustic energy in a flow duct with a vortex sheet

    NASA Astrophysics Data System (ADS)

    Boij, Susann

    2009-03-01

    Modelling the acoustic scattering and absorption at an area expansion in a flow duct requires the incorporation of the flow-acoustic interaction. One way to quantify the interaction is to study the energy in the incident and the scattered field respectively. If the interaction is strong, energy may be transferred between the acoustic and the main flow field. In particular, shear layers, that may be the result of the flow separation, are unstable to low frequency perturbations such as acoustic waves. The vortex sheet model is an analytical linear acoustic model, developed to study scattering of acoustic waves in duct with sharp edges including the interaction with primarily the separated flows that arise at sharp edges and corners. In the model the flow field at an area expansion in a duct is described as a jet issuing into the larger part of the duct. In this paper, the flow-acoustic interaction is described in terms of energy flow. The linear convective wave equation is solved for a two-dimensional, rectangular flow duct geometry. The resulting modes are classified as "hydrodynamic" and "acoustic" when separating the acoustic energy from the part of the energy arising from the steady flow field. In the downstream duct, the set of modes for this complex flow field are not orthogonal. For small Strouhal numbers, the plane wave and the two hydrodynamic waves are all plane, although propagating with different wave speeds. As the Strouhal numbers increases, the hydrodynamic modes changes to get a shape where the amplitude is concentrated near the vortex sheet. In an intermediate Strouhal number region, the mode shape of the first higher order mode is very similar to the damped hydrodynamic mode. A physical interpretation of this is that we have a strong coupling between the flow field and the acoustic field when the modes are non-orthogonal. Energy concepts for this duct configuration and mean flow profile are introduced. The energy is formulated such that the vortex

  1. On the energy spectra of secondary ions emitted from silicon and graphite single crystals

    NASA Astrophysics Data System (ADS)

    Khvostov, V. V.; Khrustachev, I. K.; Minnebaev, K. F.; Zykova, E. Yu.; Ivanenko, I. P.; Yurasova, V. E.

    2014-03-01

    Secondary ion emission from silicon and graphite single crystals bombarded by argon ions with energies E 0 varied from 1 to 10 keV at various angles of incidence α has been studied. The evolution of the energy spectra of C+ and Si+ secondary ions has been traced in which the positions of maxima ( E max) shift toward higher secondary-ion energies E 1 with increasing polar emission angle θ (measured from the normal to the sample surface). The opposite trend has been observed for ions emitted from single crystals heated to several hundred degrees Centigrade; the E max values initially remain unchanged and then shift toward lower energies E 1 with increasing angle θ. It is established that the magnitude and position of a peak in the energy spectrum of secondary C+ ions is virtually independent of E 0, angle α, and the surface relief of the sample (in the E 0 and α intervals studied). Unusual oscillating energy distributions are discussed, which have been observed for secondary ions emitted from silicon (111) and layered graphite (0001) faces. Numerical simulations of secondary ion sputtering and charge exchange have been performed. A comparison of the measured and calculated data for graphite crystals has shown that C+ ions are formed as a result of charge exchange between secondary ions and bombarding Ar+ ions, which takes place both outside and inside the target. This substantially differs from the ion sputtering process in metals and must be taken into account when analyzing secondary ion emission mechanisms and in practical applications of secondary-ion mass spectrometry.

  2. On the relationship between acoustic energy density flux near the jet axis and far field acoustic intensity

    NASA Technical Reports Server (NTRS)

    Maestrello, L.

    1973-01-01

    By measurement and analysis, the relationship between the distribution of the outflow of acoustic energy over the jet boundary and the far-field intensity is considered. The physical quantity used is the gradient of the pressure evaluated on a geometrical plane at the smallest possible radial distance from the jet axis, but outside the vortical region, in the area where the homogeneous wave equation is reasonably well satisfied. The numerical and experimental procedures involved have been checked out by using a known source. Results indicate that the acoustic power output per unit length of the jet, in the region from which the sound emanates, peaks at approximately 9 diameters downstream. The acoustic emission for a jet Strouhal number of about 0.3 exceeds the emission for all other Strouhal numbers nearly everywhere along the measurement plane. However, the far-field peak intensity distribution obtained from the contribution of each station was found to depend on the spatial extent of the region where sound emanates from the jet, which, in turn, depends more on the far-field angle than on the Strouhal number.

  3. Measurement of Underwater Operational Noise Emitted by Wave and Tidal Stream Energy Devices.

    PubMed

    Lepper, Paul A; Robinson, Stephen P

    2016-01-01

    The increasing international growth in the development of marine and freshwater wave and tidal energy harvesting systems has been followed by a growing requirement to understand any associated underwater impact. Radiated noise generated during operation is dependent on the device's physical properties, the sound-propagation environment, and the device's operational state. Physical properties may include size, distribution in the water column, and mechanics/hydrodynamics. The sound-propagation environment may be influenced by water depth, bathymetry, sediment type, and water column acoustic properties, and operational state may be influenced by tidal cycle and wave height among others This paper discusses some of the challenges for measurement of noise characteristics from these devices as well as a case study of the measurement of radiated noise from a full-scale wave energy converter. PMID:26611011

  4. Energy spectra of single neutrons and charged particles emitted following the absorption of stopped negative pions in 4He

    NASA Astrophysics Data System (ADS)

    Cernigoi, C.; Gabrielli, I.; Grion, N.; Pauli, G.; Saitta, B.; Ricci, R. A.; Boccaccio, P.; Viesti, G.

    1981-02-01

    Energy spectra have been measured of single neutrons, protons and deuterons emitted following the capture at rest of negative pions in 4He. The neutron energy spectrum has been measured with an energy resolution of 4% at 90 MeV. The absolute number of stopped pions has been measured.

  5. Transmission of wave energy in curved ducts. [acoustic propagation within rigid walls

    NASA Technical Reports Server (NTRS)

    Rostafinski, W.

    1974-01-01

    Investigation of the ability of circular bends to transmit acoustic energy flux. A formulation of wave-energy flow is developed for motion in curved ducts. A parametric study over a range of frequencies shows the ability of circular bends to transmit energy in the case of perfectly rigid walls.

  6. Backward emitted high-energy neutrons in hard reactions of p and π+ on carbon

    NASA Astrophysics Data System (ADS)

    Malki, A.; Piasetzky, E.; Alster, J.; Asryan, G.; Averichev, Y.; Barton, D.; Baturin, V.; Bukhtoyarova, N.; Carroll, A.; Heppelmann, S.; Kawabata, T.; Leksanov, A.; Makdisi, Y.; Minina, E.; Navon, I.; Nicholson, H.; Ogawa, A.; Panebratsev, Yu.; Schetkovsky, A.; Shimanskiy, S.; Tang, A.; Watson, J. W.; Yoshida, H.; Zhalov, D.

    2000-12-01

    Beams of protons and pions of 5.9 GeV/c were incident on a C target. Neutrons emitted into the back hemisphere, in the laboratory system, were detected in (triple) coincidence with two emerging pt>0.6 GeV/c particles. We present the momentum spectra of the backward going neutrons. We also integrated the spectra and determined the fraction of the hard scattering events which are in coincidence with at least one neutron emitted into the back hemisphere, with momenta above 0.32 GeV/c. Contrary to the earlier measurements which found that only a small fraction (of the order of 10%) of the total inelastic cross section for light nuclei was associated with backward going nucleons, we find that about half of the events are of this nature. We speculate that the reason for the large difference is due to the strong dependence of the hard-scattering reaction upon the total center of mass energy(s) and short range nucleon correlations in nuclei.

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

    PubMed

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

    2011-09-01

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

  8. Data on energy end-use patterns and energy efficiencies in major CO sub 2 emitting countries

    SciTech Connect

    Cheng, Hsing C.

    1990-08-01

    This is a report of the basic data regarding energy end-uses and efficiencies in major CO{sub 2} emitting countries. The task is part of the multi-lab carbon dioxide energy system research program. Fossil energy production and use are the largest anthropogenic source of CO{sub 2} emissions. To gain an insight into the relationship between CO{sub 2} emission and energy use, the global energy consumption patterns and the changing energy efficiencies must be better analyzed and understood. This work attempts to collect and organize the data on energy use and energy efficiency for the ten major CO{sub 2} emitting countries: USA, USSR, the People's Republic of China, Japan, the Federal Republic of Germany, the United Kingdom, France, Canada, Italy, and Australia. A wide variety of information sources have been examined. The data base is presented in tabular format. It is documented by three main parts, the first shows the total final energy consumption by fuel type and end-use sector for each nation. The second shows the detailed energy use by fuel type and function for each end-use sector: residential, commercial, transportation and industrial. The third part shows the country-specific energy balances for electricity generation and use. The data base is a living document and will be updated as additional information becomes available. The data base is to be used to accomplish the ultimate objective of improving the reliability of future CO{sub 2}-emissions estimates. 7 refs., 12 tabs.

  9. Energy-efficiency of optical network units with vertical-cavity surface-emitting lasers.

    PubMed

    Wong, Elaine; Mueller, Michael; Dias, Maluge P I; Chan, Chien Aun; Amann, Markus C

    2012-07-01

    The energy savings of 10 Gbps vertical-cavity surface-emitting lasers (VCSELs) for use in energy-efficient optical network units (ONUs) is critically examined in this work. We experimentally characterize and analytically show that the fast settling time and low power consumption during active and power-saving modes allow the VCSEL-ONU to achieve significant energy savings over the distributed feedback laser (DFB) based ONU. The power consumption per customer using VCSEL-ONUs and DFB-ONUs, is compared through an illustrative example of 10G-EPON for Video-on-Demand delivery. Using energy consumption models and numerical analyses in sleep and doze mode operations, we present an impact study of network and protocol parameters, e.g. polling cycle time, network load, and upstream access scheme used, on the achievable energy savings of VCSEL-ONUs over DFB-ONUs. Guidance on the specific power-saving mode to maximum energy savings throughout the day, is also presented. PMID:22772191

  10. Backward emitted high-energy neutrons in hard reactions of p and π+ on carbon

    NASA Astrophysics Data System (ADS)

    Malki, A.; Alster, J.; Asryan, G.; Averichev, Y.; Barton, D.; Baturin, V.; Bukhtoyarova, N.; Carroll, A.; Heppelmann, S.; Kawabata, T.; Leksanov, A.; Makdisi, Y.; Minina, E.; Navon, I.; Nicholson, H.; Ogawa, A.; Panebratsev, Yu.; Piasetzky, E.; Schetkovsky, A.; Shimanskiy, S.; Tang, A.; Watson, J. W.; Yoshida, H.; Zhalov, D.

    2002-01-01

    Beams of protons and pions of 5.9 GeV/c were incident on a C target. Neutrons emitted into the backward hemisphere, in the laboratory system, were detected in (triple) coincidence with two emerging particles of tranverse momenta pt>0.6 GeV/c. We determined that for (46.5+/-3.7)% of the proton-induced events and for (40.8+/-4.5)% of the pion-induced events with the two high-pt particles, there is also at least one backward emitted neutron with momentum greater than 0.32 GeV/c. This observation is in sharp contrast to a well- established universal pattern from a large variety of earlier inclusive measurements with hadrons, electrons, photons, neutrinos, and antineutrinos where the probability for backward nucleon emission was in the 5 to 10 % range. We present also a measurement of the momentum spectra for the backward going neutrons. The spectra have the same universal shape observed in the inclusive reactions. We speculate that the enhanced backward neutron emission in this semi-inclusive region could be an indication for a strong dependence of the cross section on the squared total center-of-mass energy (s) and for the importance of short-range nucleon-nucleon correlations.

  11. [Physiological-occupational assessment of acoustic load with equal energy but different time and informational characteristics].

    PubMed

    Suvorov, G A; Shkarinov, L N; Kravchenko, O K; Kur'erov, N N

    1999-01-01

    The article deals with results of experimental study comparing effects of 4 types of acoustic load--noise (constant and impulse) and music (electronic symphonic one and rap)--on hearing sensitivity, processes in nervous system and subjective evaluation. All types of acoustic load were equal in energy (on evaluation according to equivalent level during the experiment). The study included 2 levels of load--90 and 95 dB. The differences revealed demonstrate importance of impulse parameters of noise and musical load for reactions of acoustic analyzer and central nervous system. The experiments show that evaluation of harm caused by temporary and impulse noises should be based not only on assessment of specific (hearing) function, but also on parameters of central nervous system state. The authors found that music of certain acoustic and informational parameters may harm hearing function. PMID:10420710

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

    NASA Astrophysics Data System (ADS)

    Summers, Jason E.

    2003-11-01

    A frequency-dependent model for reverberant energy in coupled rooms is developed and compared with measurements for a 1:10 scale model and for Bass Hall, Ft. Worth, TX. At high frequencies, prior statistical-acoustics models are improved by geometrical-acoustics corrections for decay within sub-rooms and for energy transfer between sub-rooms. Comparisons of computational geometrical acoustics predictions based on beam-axis tracing with scale model measurements indicate errors resulting from tail-correction assuming constant quadratic growth of reflection density. Using ray tracing in the late part corrects this error. For mid-frequencies, the models are modified to account for wave effects at coupling apertures by including power transmission coefficients. Similarly, statical-acoustics models are improved through more accurate estimates of power transmission measurements. Scale model measurements are in accord with the predicted behavior. The edge-diffraction model is adapted to study transmission through apertures. Multiple-order scattering is theoretically and experimentally shown inaccurate due to neglect of slope diffraction. At low frequencies, perturbation models qualitatively explain scale model measurements. Measurements confirm relation of coupling strength to unperturbed pressure distribution on coupling surfaces. Measurements in Bass Hall exhibit effects of the coupled stage house. High frequency predictions of statistical acoustics and geometrical acoustics models and predictions of coupling apertures all agree with measurements.

  13. Seismic-acoustic energy partitioning during a paroxysmal eruptive phase of Tungurahua volcano, Ecuador

    NASA Astrophysics Data System (ADS)

    Palacios, Pablo B.; Díez, Mikel; Kendall, J.-Michael; Mader, Heidy M.

    2016-04-01

    Studies of discrete volcanic explosions, that usually last less than two or three minutes, have suggested that the partitioning of seismic-acoustic energy is likely related to a range of physical mechanisms that depend on magma properties and other physical constraints such as the location of the fragmentation surface. In this paper we explore the energy partition of a paroxysmal eruptive phase of Tungurahua volcano that lasted for over four hours, on 2006 July 14 - 15, using seismic-acoustic information recorded by stations on its flanks (near field). We find evidence of a linear scaling between seismic and acoustic energies, with time dependent intensities, during the sustained explosive phase of the eruption. Furthermore, we argue that this scaling can be explained by two different processes: (1) the fragmentation region ultimately acts as the common source of energy producing both direct seismic waves, that travel through the volcanic edifice, and direct acoustic waves coming from a disturbed atmosphere above the summit; (2) the coupling of acoustic waves with the ground to cause seismic waves. Both processes are concurrent, however we have found that the first one is dominant for seismic records below 4 Hz. Here we use the linear scaling of intensities to construct seismic and acoustic indices, which, we argue, could be used to track an ongoing eruption. Thus, especially in strong paroxysms that can produce pyroclastic flows, the index correlation and their levels can be used as quantitative monitoring parameters to assess the volcanic hazard in real time. Additionally, we suggest from the linear scaling that the source type for both cases, seismic and acoustic, is dipolar and dominant in the near field.

  14. Seismic-acoustic energy partitioning during a paroxysmal eruptive phase of Tungurahua volcano, Ecuador

    NASA Astrophysics Data System (ADS)

    Palacios, Pablo B.; Díez, Mikel; Kendall, J.-Michael; Mader, Heidy M.

    2016-06-01

    Studies of discrete volcanic explosions, that usually last less than 2 or 3 min, have suggested that the partitioning of seismic-acoustic energy is likely related to a range of physical mechanisms that depend on magma properties and other physical constraints such as the location of the fragmentation surface. In this paper, we explore the energy partition of a paroxysmal eruptive phase of Tungurahua volcano that lasted for over 4 hr, on 2006 July 14-15, using seismic-acoustic information recorded by stations on its flanks (near field). We find evidence of a linear scaling between seismic and acoustic energies, with time-dependent intensities, during the sustained explosive phase of the eruption. Furthermore, we argue that this scaling can be explained by two different processes: (1) the fragmentation region ultimately acts as the common source of energy producing both direct seismic waves, that travel through the volcanic edifice, and direct acoustic waves coming from a disturbed atmosphere above the summit; (2) the coupling of acoustic waves with the ground to cause seismic waves. Both processes are concurrent, however we have found that the first one is dominant for seismic records below 4 Hz. Here we use the linear scaling of intensities to construct seismic and acoustic indices, which, we argue, could be used to track an ongoing eruption. Thus, especially in strong paroxysms that can produce pyroclastic flows, the index correlation and their levels can be used as quantitative monitoring parameters to assess the volcanic hazard in real time. Additionally, we suggest from the linear scaling that the source type for both cases, seismic and acoustic, is dipolar and dominant in the near field.

  15. Discovery of a Fanaroff-Riley type 0 radio galaxy emitting at γ-ray energies

    NASA Astrophysics Data System (ADS)

    Grandi, Paola; Capetti, Alessandro; Baldi, Ranieri D.

    2016-03-01

    We present supporting evidence for the first association of a Fermi source, 3FGLJ1330.0-3818, Acero et al. (2015) with the Fanaroff-Riley type 0 (FR 0) radio galaxy Tol1326-379. FR 0s represent the majority of the local population of radio-loud active galactic nuclei but their nature is still unclear. They share the same nuclear and host properties as FR Is, but they show a large deficit of extended radio emission. Here we show that FR 0s can emit photons at very high energies. Tol1326-379 has a GeV luminosity of L>1 GeV ˜ 2 × 1042 erg s-1, typical of FR Is, but with a steeper γ-ray spectrum (Γ = 2.78 ± 0.14). This could be related to the intrinsic jet properties but also to a different viewing angle.

  16. Organic light-emitting devices integrated with solar cells: High contrast and energy recycling

    NASA Astrophysics Data System (ADS)

    Yang, Chih-Jen; Cho, Ting-Yi; Lin, Chun-Liang; Wu, Chung-Chih

    2007-04-01

    In this letter, the authors report that by integrating organic light-emitting devices (OLEDs) with solar cells, luminous ambient-light reflection as low as 1.4% (even superior to that achieved with polarizers) can be achieved without compromising the electroluminescence efficiency for high-contrast display applications. Furthermore, in such a configuration, the photon energies of the incident ambient light and the portion of OLED emission not getting outside of the device can be recycled into useful electrical power via the photovoltaic action, instead of being totally wasted as in other reported contrast-enhancement techniques. These features, the authors believe, shall make this technique attractive for high-contrast display applications and portable/mobile electronics that are highly power aware.

  17. Acoustic-emission linear-pulse holography

    SciTech Connect

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

    1982-06-01

    This paper describes Acoustic Emission Linear Pulse Holography which combines the advantages of linear imaging and acoustic emission into a single NDE inspection system. This unique system produces a chronological linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. Conventional linear holographic imaging uses an ultrasonic transducer to transmit energy into the volume being imaged. When the crack or defect reflects that energy, the crack acts as a new source of acoustic waves. To formulate an image of that source, a receiving transducer is scanned over the volume of interest and the phase of the received signals is measured at successive points on the scan. The innovation proposed here is the utilization of the crack generated acoustic emission as the acoustic source and generation of a line image of the crack as it grows. A thirty-two point sampling array is used to construct phase-only linear holograms of simulated acoustic emission sources on large metal plates. The phases are calculated using the pulse time-of-flight (TOF) times from the reference transducer to the array of receivers. Computer reconstruction of the image is accomplished using a one-dimensional FFT algorithm (i.e., backward wave). Experimental results are shown which graphically illustrate the unique acoustic emission images of a single point and a linear crack in a 100 mm x 1220 mm x 1220 mm aluminum plate.

  18. Theoretical Estimation of the Acoustic Energy Generation and Absorption Caused by Jet Oscillation

    NASA Astrophysics Data System (ADS)

    Takahashi, Kin'ya; Iwagami, Sho; Kobayashi, Taizo; Takami, Toshiya

    2016-04-01

    We investigate the energy transfer between the fluid field and acoustic field caused by a jet driven by an acoustic particle velocity field across it, which is the key to understanding the aerodynamic sound generation of flue instruments, such as the recorder, flute, and organ pipe. Howe's energy corollary allows us to estimate the energy transfer between these two fields. For simplicity, we consider the situation such that a free jet is driven by a uniform acoustic particle velocity field across it. We improve the semi-empirical model of the oscillating jet, i.e., exponentially growing jet model, which has been studied in the field of musical acoustics, and introduce a polynomially growing jet model so as to apply Howe's formula to it. It is found that the relative phase between the acoustic oscillation and jet oscillation, which changes with the distance from the flue exit, determines the quantity of the energy transfer between the two fields. The acoustic energy is mainly generated in the downstream area, but it is consumed in the upstream area near the flue exit in driving the jet. This theoretical examination well explains the numerical calculation of Howe's formula for the two-dimensional flue instrument model in our previous work [Fluid Dyn. Res. 46, 061411 (2014)] as well as the experimental result of Yoshikawa et al. [J. Sound Vib. 331, 2558 (2012)].

  19. Resource Evaluation and Energy Production Estimate for a Tidal Energy Conversion Installation using Acoustic Flow Measurements

    NASA Astrophysics Data System (ADS)

    Gagnon, Ian; Baldwin, Ken; Wosnik, Martin

    2015-11-01

    The ``Living Bridge'' project plans to install a tidal turbine at Memorial Bridge in the Piscataqua River at Portsmouth, NH. A spatio-temporal tidal energy resource assessment was performed using long term bottom-deployed Acoustic Doppler Current Profilers ADCP. Two locations were evaluated: at the planned deployment location and mid-channel. The goal was to determine the amount of available kinetic energy that can be converted into usable electrical energy on the bridge. Changes in available kinetic energy with ebb/flood and spring/neap tidal cycles and electrical energy demand were analyzed. A system model is used to calculate the net energy savings using various tidal generator and battery bank configurations. Differences in the tidal characteristics between the two measurement locations are highlighted. Different resource evaluation methodologies were also analyzed, e.g., using a representative ADCP ``bin'' vs. a more refined, turbine-geometry-specific methodology, and using static bin height vs. bin height that move w.r.t. the free surface throughout a tidal cycle (representative of a bottom-fixed or floating turbine deployment, respectively). ADCP operating frequencies and bin sizes affect the standard deviation of measurements, and measurement uncertainties are evaluated. Supported by NSF-IIP grant 1430260.

  20. Evaluation of high-energy brachytherapy source electronic disequilibrium and dose from emitted electrons

    SciTech Connect

    Ballester, Facundo; Granero, Domingo; Perez-Calatayud, Jose; Melhus, Christopher S.; Rivard, Mark J.

    2009-09-15

    Purpose: The region of electronic disequilibrium near photon-emitting brachytherapy sources of high-energy radionuclides ({sup 60}Co, {sup 137}Cs, {sup 192}Ir, and {sup 169}Yb) and contributions to total dose from emitted electrons were studied using the GEANT4 and PENELOPE Monte Carlo codes. Methods: Hypothetical sources with active and capsule materials mimicking those of actual sources but with spherical shape were examined. Dose contributions due to source photons, x rays, and bremsstrahlung; source {beta}{sup -}, Auger electrons, and internal conversion electrons; and water collisional kerma were scored. To determine if conclusions obtained for electronic equilibrium conditions and electron dose contribution to total dose for the representative spherical sources could be applied to actual sources, the {sup 192}Ir mHDR-v2 source model (Nucletron B.V., Veenendaal, The Netherlands) was simulated for comparison to spherical source results and to published data. Results: Electronic equilibrium within 1% is reached for {sup 60}Co, {sup 137}Cs, {sup 192}Ir, and {sup 169}Yb at distances greater than 7, 3.5, 2, and 1 mm from the source center, respectively, in agreement with other published studies. At 1 mm from the source center, the electron contributions to total dose are 1.9% and 9.4% for {sup 60}Co and {sup 192}Ir, respectively. Electron emissions become important (i.e., >0.5%) within 3.3 mm of {sup 60}Co and 1.7 mm of {sup 192}Ir sources, yet are negligible over all distances for {sup 137}Cs and {sup 169}Yb. Electronic equilibrium conditions along the transversal source axis for the mHDR-v2 source are comparable to those of the spherical sources while electron dose to total dose contribution are quite different. Conclusions: Electronic equilibrium conditions obtained for spherical sources could be generalized to actual sources while electron contribution to total dose depends strongly on source dimensions, material composition, and electron spectra.

  1. Contributed Review: Recent developments in acoustic energy harvesting for autonomous wireless sensor nodes applications

    NASA Astrophysics Data System (ADS)

    Khan, Farid Ullah; Khattak, Muhammad Umair

    2016-02-01

    Rapid developments in micro electronics, micro fabrication, ultra-large scale of integration, ultra-low power sensors, and wireless technology have greatly reduced the power consumption requirements of wireless sensor nodes (WSNs) and make it possible to operate these devices with energy harvesters. Likewise, other energy harvesters, acoustic energy harvesters (AEHs), have been developed and are gaining swift interest in last few years. This paper presents a review of AEHs reported in the literature for the applications of WSNs. Based on transduction mechanism, there are two types of AEHs: piezoelectric acoustic energy harvesters (PEAEHs) and electromagnetic acoustic energy harvesters (EMAEHs). The reported AEHs are mostly characterized under the sound pressure level (SPL) that ranges from 45 to 161 dB. The range for resonant frequency of the produced AEHs is from 146 Hz to 24 kHz and these produced 0.68 × 10-6 μW to 30 mW power. The maximum power (30 mW) is produced by a PEAEH, when the harvester is subjected to a SPL of 161 dB and 2.64 kHz frequency. However, for EMAEHs, the maximum power reported is about 1.96 mW (at 125 dB and 143 Hz). Under the comparable SPLs, the power production by the reported EMAEHs is relatively better than that of PEAEHs, moreover, due to lower resonant frequency, the EMAEHs are more feasible for the low frequency band acoustical environment.

  2. Thermal Acoustic Sensor for High Pulse Energy X-ray FEL Beams

    SciTech Connect

    Smith, T.J.; Frisch, J.C.; Kraft, E.M.; Loos, J.; Bentsen, G.S.; /Rochester U.

    2011-12-13

    The pulse energy density of X-ray FELs will saturate or destroy conventional X-ray diagnostics, and the use of large beam attenuation will result in a beam that is dominated by harmonics. We present preliminary results at the LCLS from a pulse energy detector based on the thermal acoustic effect. In this type of detector an X-ray resistant material (boron carbide in this system) intercepts the beam. The pulse heating of the target material produces an acoustic pulse that can be detected with high frequency microphones to produce a signal that is linear in the absorbed energy. The thermal acoustic detector is designed to provide first- and second-order calorimetric measurement of X-ray FEL pulse energy. The first-order calorimetry is a direct temperature measurement of a target designed to absorb all or most of the FEL pulse power with minimal heat leak. The second-order measurement detects the vibration caused by the rapid thermoelastic expansion of the target material each time it absorbs a photon pulse. Both the temperature change and the amplitude of the acoustic signal are directly related to the photon pulse energy.

  3. Contributed Review: Recent developments in acoustic energy harvesting for autonomous wireless sensor nodes applications.

    PubMed

    Khan, Farid Ullah; Khattak, Muhammad Umair

    2016-02-01

    Rapid developments in micro electronics, micro fabrication, ultra-large scale of integration, ultra-low power sensors, and wireless technology have greatly reduced the power consumption requirements of wireless sensor nodes (WSNs) and make it possible to operate these devices with energy harvesters. Likewise, other energy harvesters, acoustic energy harvesters (AEHs), have been developed and are gaining swift interest in last few years. This paper presents a review of AEHs reported in the literature for the applications of WSNs. Based on transduction mechanism, there are two types of AEHs: piezoelectric acoustic energy harvesters (PEAEHs) and electromagnetic acoustic energy harvesters (EMAEHs). The reported AEHs are mostly characterized under the sound pressure level (SPL) that ranges from 45 to 161 dB. The range for resonant frequency of the produced AEHs is from 146 Hz to 24 kHz and these produced 0.68 × 10(-6) μW to 30 mW power. The maximum power (30 mW) is produced by a PEAEH, when the harvester is subjected to a SPL of 161 dB and 2.64 kHz frequency. However, for EMAEHs, the maximum power reported is about 1.96 mW (at 125 dB and 143 Hz). Under the comparable SPLs, the power production by the reported EMAEHs is relatively better than that of PEAEHs, moreover, due to lower resonant frequency, the EMAEHs are more feasible for the low frequency band acoustical environment. PMID:26931827

  4. Nonlinear effects of dark energy clustering beyond the acoustic scales

    SciTech Connect

    Anselmi, Stefano; Sefusatti, Emiliano E-mail: dlopez_n@ictp.it

    2014-07-01

    We extend the resummation method of Anselmi and Pietroni (2012) to compute the total density power spectrum in models of quintessence characterized by a vanishing speed of sound. For standard ΛCDM cosmologies, this resummation scheme allows predictions with an accuracy at the few percent level beyond the range of scales where acoustic oscillations are present, therefore comparable to other, common numerical tools. In addition, our theoretical approach indicates an approximate but valuable and simple relation between the power spectra for standard quintessence models and models where scalar field perturbations appear at all scales. This, in turn, provides an educated guess for the prediction of nonlinear growth in models with generic speed of sound, particularly valuable since no numerical results are yet available.

  5. Enhanced acoustoelectric coupling in acoustic energy harvester using dual Helmholtz resonators.

    PubMed

    Peng, Xiao; Wen, Yumei; Li, Ping; Yang, Aichao; Bai, Xiaoling

    2013-10-01

    In this paper, enhanced acoustoelectric transduction in an acoustic energy harvester using dual Helmholtz resonators has been reported. The harvester uses a pair of cavities mechanically coupled with a compliant perforated plate to enhance the acoustic coupling between the cavity and the plate. The experimental results show that the volume optimization of the second cavity can significantly increase the generated electric voltage up to 400% and raise the output power to 16 times as large as that of a harvester using a single Helmholtz resonator at resonant frequencies primarily related to the plate. PMID:24081260

  6. Highly efficient greenish-blue platinum-based phosphorescent organic light-emitting diodes on a high triplet energy platform

    SciTech Connect

    Chang, Y. L. Gong, S. White, R.; Lu, Z. H.; Wang, X.; Wang, S.; Yang, C.

    2014-04-28

    We have demonstrated high-efficiency greenish-blue phosphorescent organic light-emitting diodes (PHOLEDs) based on a dimesitylboryl-functionalized C^N chelate Pt(II) phosphor, Pt(m-Bptrz)(t-Bu-pytrz-Me). Using a high triplet energy platform and optimized double emissive zone device architecture results in greenish-blue PHOLEDs that exhibit an external quantum efficiency of 24.0% and a power efficiency of 55.8 lm/W. This record high performance is comparable with that of the state-of-the-art Ir-based sky-blue organic light-emitting diodes.

  7. Lyman Alpha Emitting Galaxies at 2 < z < 3: Towards a Calibrated Probe of Dark Energy

    SciTech Connect

    Caryl Gronwall

    2012-12-03

    The goal of this project was to establish the physical properties of Ly{alpha} emitting galaxies from redshifts of 2 to 3 in order to better calibrate the use of LAEs as probes of the large scale structure of the universe for upcoming dark energy experiments, such as the Hobby Eberly Telescope Dark Energy Experiment (HETDEX). We have obtained narrow-band imaging of the Extended Chandra Deep Field South (ECDF-S) in two different narrow-band filters centered at Ly{alpha} at z=2.1 and 3.1. The resulting of samples of LAEs were used to determine the LAE luminosity function, equivalent width distribution and clustering properties (bias) of LAEs at these redshifts. While the results from the ECDF-S appear robust, they are based on a single field. To explore the effects of cosmic variance and galaxy environment on the physical properties of LAEs, we have also obtained narrow-band data at both redshifts (z = 2:1 and 3:1) in three additional fields (SDSS 1030+-05, the Extended Hubble Deep Field South, and CW 1255+01). The narrow-band imaging data has been reduced and LAE catalogs are being generated. We have calculated preliminary luminosity functions, equivalent width distributions, and clustering properties. We have also obtained follow-up spectroscopy in the optical (using VLT/FORS) and in the near-infrared (using Magellan/MMIRS). Since individual LAEs have too little S/N to enable meaningful fits for stellar population parameters, our previous work has analyzed stacked Spectral Energy Distributions (SEDs). SED fitting was performed on several subsets of LAEs selected by their rest-UV luminosity, UV spectral slope, Ly alpha luminosity, Equivalent Width, or rest-optical (IRAC) luminosity.

  8. Nonlinear dust acoustic waves in a mixed nonthermal high energy-tail electron distribution

    SciTech Connect

    Younsi, Smain; Tribeche, Mouloud

    2008-07-15

    Large amplitude as well as weakly nonlinear dust acoustic waves in a mixed nonthermal high-energy-tail electron distribution are investigated. The effects of charge variation and electron deviation from Boltzmann distribution on the large amplitude dust acoustic soliton are then considered. The dust charge variation leads to an additional enlargement of the dust acoustic soliton, which is more pronounced as the electrons evolve far away from Maxwell-Boltzmann distribution. Under certain conditions, the dust charge fluctuation may provide an alternate physical mechanism causing anomalous dissipation, the strength of which becomes important and may prevail over that of dispersion as the suprathermal character of the plasma becomes important. The results complement and provide new insights into our previously published results on this problem [K. Aoutou, M. Tribeche, and T. H. Zerguini, Phys. Plasmas 15, 013702 (2008)].

  9. Design and Implementation of an Acoustic X-ray Detector to Measure the LCLS Beam Energy

    SciTech Connect

    Loos, Jennifer L.; /San Jose State U. /SLAC

    2010-08-25

    On April 11, 2009, first light was seen from LCLS. The present apparatus being used to measure the x-ray beam energy is the Total Energy Sensor which uses a suite of thermal sensors. Another device is needed to cross-check the energy measurements. This new diagnostic tool utilizes radiation acoustic phenomena to determine the x-ray beam energy. A target is hit by the x-rays from the beam, and a voltage is generated in two piezoelectric sensors attached to the target in response to the consequent deformation. Once the voltage is known, the power can be obtained. Thermal sensors will also be attached to the target for calibration purposes. Material selection and design were based on: durability, ultra-high vacuum compatibility, safety and thermal properties. The target material was also chosen for its acoustic properties which were determined from tests using a frequency generator and laser. Initial tests suggest the device will function as anticipated.

  10. Tracking Energy Flow Using a Volumetric Acoustic Intensity Imager (VAIM)

    NASA Technical Reports Server (NTRS)

    Klos, Jacob; Williams, Earl G.; Valdivia, Nicolas P.

    2006-01-01

    A new measurement device has been invented at the Naval Research Laboratory which images instantaneously the intensity vector throughout a three-dimensional volume nearly a meter on a side. The measurement device consists of a nearly transparent spherical array of 50 inexpensive microphones optimally positioned on an imaginary spherical surface of radius 0.2m. Front-end signal processing uses coherence analysis to produce multiple, phase-coherent holograms in the frequency domain each related to references located on suspect sound sources in an aircraft cabin. The analysis uses either SVD or Cholesky decomposition methods using ensemble averages of the cross-spectral density with the fixed references. The holograms are mathematically processed using spherical NAH (nearfield acoustical holography) to convert the measured pressure field into a vector intensity field in the volume of maximum radius 0.4 m centered on the sphere origin. The utility of this probe is evaluated in a detailed analysis of a recent in-flight experiment in cooperation with Boeing and NASA on NASA s Aries 757 aircraft. In this experiment the trim panels and insulation were removed over a section of the aircraft and the bare panels and windows were instrumented with accelerometers to use as references for the VAIM. Results show excellent success at locating and identifying the sources of interior noise in-flight in the frequency range of 0 to 1400 Hz. This work was supported by NASA and the Office of Naval Research.

  11. Low frequency acoustic energy harvesting using PZT piezoelectric plates in a straight tube resonator

    NASA Astrophysics Data System (ADS)

    Li, Bin; You, Jeong Ho; Kim, Yong-Joe

    2013-05-01

    A novel and practical acoustic energy harvesting mechanism to harvest traveling sound at low audible frequency is introduced and studied both experimentally and numerically. The acoustic energy harvester in this study contains a quarter-wavelength straight tube resonator with lead zirconate titanate (PZT) piezoelectric cantilever plates placed inside the tube. When the tube resonator is excited by an incident sound at its acoustic resonance frequency, the amplified acoustic pressure inside the tube drives the vibration motions of piezoelectric plates, resulting in the generation of electricity. To increase the total voltage and power, multiple PZT plates were placed inside the tube. The number of PZT plates to maximize the voltage and power is limited due to the interruption of air particle motion by the plates. It has been found to be more beneficial to place the piezoelectric plates in the first half of the tube rather than along the entire tube. With an incident sound pressure level of 100 dB, an output voltage of 5.089 V was measured. The output voltage increases linearly with the incident sound pressure. With an incident sound pressure of 110 dB, an output voltage of 15.689 V and a power of 12.697 mW were obtained. The corresponding areal and volume power densities are 0.635 mW cm-2 and 15.115 μW cm-3, respectively.

  12. 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.

  13. PEDOT as a Flexible Organic Electrode for a Thin Film Acoustic Energy Harvester.

    PubMed

    Kim, Younghoon; Na, Jongbeom; Park, Chihyun; Shin, Haijin; Kim, Eunkyoung

    2015-08-01

    An efficient thin film acoustic energy harvester was explored using flexible poly(3,4-ethylene dioxythiophene) (PEDOT) films as electrodes in an all-organic triboelectric generator (AO-TEG). A thin film AO-TEG structured as PEDOT/Kapton//PET/PEDOT was prepared by the solution casting polymerization(SCP) on the dielectric polymer films. As-prepared AO-TEG showed high flexibility and durability due to the strong adhesion between the electrodes and the dielectric polymer. The short-circuit current density (Jsc), open-circuit voltage (Voc), and maximum power density (Pw) reached 50 mA/m(2), 700 V, and 12.9 W/m(2) respectively. The output current density decreased with the increase in the electrode resistance (Re), but the energy loss in the organic electrodes was negligible. The AO-TEG could light up 180 LEDs instantaneously upon touching of the AO-TEG with a palm (∼120 N). With the flexible structure, the AO-TEG was worn as clothes and generated electricity to light LEDs upon regular human movement. Furthermore, the AO-TEG was applicable as a thin film acoustic energy harvester, which used music to generate electricity enough for powering of 5 LEDs. An AO-TEG with a PEDOT electrode (Re = 200 Ω) showed instantaneous peak-to-peak voltage generation of 11 V under a sound pressure level (SPL) of 90-100 dB. The harvested acoustic energy through the AO-TEG was 350 μJ from the 4 min playing of the same single song. This is the first demonstration of a flexible triboelectric generator (TEG) using an organic electrode for harvesting acoustic energy from ambient environment. PMID:26153798

  14. Generalized acoustic energy density based active noise control in single frequency diffuse sound fields.

    PubMed

    Xu, Buye; Sommerfeldt, Scott D

    2014-09-01

    In a diffuse sound field, prior research has established that a secondary source can theoretically achieve perfect cancellation at an error microphone in the far field of the secondary source. However, the sound pressure level is generally only reduced in a small zone around the error sensor, and at a distance half of a wavelength away from the error sensor, the averaged sound pressure level will be increased by more than 10 dB. Recently an acoustic energy quantity, referred to as the generalized acoustic energy density (GED), has been introduced. The GED is obtained by using a weighting factor in the formulation of total acoustic energy density. Different values of the weighting factor can be chosen for different applications. When minimizing the GED at the error sensor, one can adjust the weighting factor to increase the spatial extent of the "quiet zone" and to achieve a desired balance between the degree of attenuation in the quiet zone and the total energy added into the sound field. PMID:25190386

  15. Effect of wind and temperature gradients on received acoustic energy

    NASA Technical Reports Server (NTRS)

    Brienzo, Richard K.

    1990-01-01

    The effect of refraction due to wind and temperature gradients on energy received from low flying aircraft is examined. A series of helicopter and jet flyby's were recorded with a microphone array on two separate days, each with distinctly different meteorological conditions. Energy in the 100 to 200 Hertz band is shown as a function of aircraft range from the array, and compared with the output of the Fast Field Program.

  16. Low-Energy Electrons Emitted in Ion Collisions with Thin Foils

    NASA Astrophysics Data System (ADS)

    Kraemer, Michael; Kozhuharov, Christophor; Durante, Marco; Hagmann, Siegbert; Kraft, Gerhard; Lineva, Natallia

    The realistic description of radiation damage after charged particle passage is an ongoing issue for both radiotherapy as well as space applications. In both areas of applied radiological science, living as well as nonliving matter is exposed to ionizing radiation, and it is of vital interest to predict the responses of structures like cells, detectors or electronic devices. In ion beam radiotherapy, for example, the Local Effect Model (LEM) is being used to calculate radiobiological effects with so far unprecedented versatility. This has been shown in the GSI radiotherapy pilot project and consequently this model has become the "industry standard" for treatment planning in subsequent commercial ion radiotherapy sites. The model has also been extended to nonliving matter, i.e. to describe the response of solid state detectors such as TLDs and films. A prerequisite for this model (and possibly similar ones) is the proper description of microscopic track structure and energy deposition. In particular, the area at a very low distance (¡20 nm) from the ion path needs special attention due to the locally very high dose and the rather limited experimental evidence for the shape of the dose distribution. The dose distribution at low distances is inevitably associated with the creation and transport of low-energy (sub-keV) electrons. While some data, elementary cross sections as well as dose distributions, exist for gaseous media, i.e. under single collision conditions, experimental data for the condensed phase are scarce. We have, therefore, launched a project aimed at systematic research of the energy and angular distributions of low-energy (sub-keV) electrons emitted from solids. These investigations com-prise creation as well as transport of low-energy electrons under multiple collision conditions and hence require accounting for the properties of the target, both bulk and surface, i.e. for the inherent inhomogeneity of the thickness and for the surface roughness. To

  17. Negative Refraction and Energy Funneling by Hyperbolic Materials: An Experimental Demonstration in Acoustics

    NASA Astrophysics Data System (ADS)

    García-Chocano, Victor M.; Christensen, Johan; Sánchez-Dehesa, José

    2014-04-01

    This Letter reports the design, fabrication, and experimental characterization of hyperbolic materials showing negative refraction and energy funneling of airborne sound. Negative refraction is demonstrated using a stack of five holey Plexiglas plates where their thicknesses, layer separation, hole diameters, and lattice periodicity have been determined to show hyperbolic dispersion around 40 kHz. The resulting hyperbolic material shows a flat band profile in the equifrequency contour allowing the gathering of acoustic energy in a broad range of incident angles and its funneling through the material. Our demonstrations foresee interesting developments based on both phenomena. Acoustic imaging with subwavelength resolution and spot-size converters that harvest and squeeze sound waves irradiating from many directions into a collimated beam are just two possible applications among many.

  18. Energy Migration Engineering of Bright Rare-Earth Upconversion Nanoparticles for Excitation by Light-Emitting Diodes.

    PubMed

    Zhong, Yeteng; Rostami, Iman; Wang, Zihua; Dai, Hongjie; Hu, Zhiyuan

    2015-11-01

    A novel Nd(3+) -sensitized upconversion nanoparticle (UCNP) that can be excited by near-infrared 740 nm light-emitting diode (LED) lamps with bright upconversion luminescence is designed. Yb(3+) ion distribution is engineered to increase the energy migration efficiency. The benefit of the novel LED-excited UCNPs is demonstrated by imaging of breast cancer cells and enabling an economic handheld semiquantitative visual measurement device. PMID:26393770

  19. Nearly 100% triplet harvesting in conventional fluorescent dopant-based organic light-emitting devices through energy transfer from exciplex.

    PubMed

    Liu, Xiao-Ke; Chen, Zhan; Zheng, Cai-Jun; Chen, Miao; Liu, Wei; Zhang, Xiao-Hong; Lee, Chun-Sing

    2015-03-25

    Nearly 100% triplet harvesting in conventional fluorophor-based organic light-emitting devices is realized through energy transfer from exciplex. The best C545T-doped device using the exciplex host exhibits a maximum current efficiency of 44.0 cd A(-1) , a maximum power efficiency of 46.1 lm W(-1) , and a maximum external quantum efficiency of 14.5%. PMID:25676085

  20. Acoustic noise and pneumatic wave vortices energy harvesting on highways

    NASA Astrophysics Data System (ADS)

    Pogacian, S.; Bot, A.; Zotoiu, D.

    2012-02-01

    This paper is aimed to present the structure and the principle of a energy harvesting system that uses the air movement emanated from passing traffic to produce and accumulate electrical energy. Each of the system's elements consists of a inertial mass panel which oscillate when driving cars pass. The panel is attached to a linear electromagnetic mini generator (or/and some piezo electric micro generators) and at the time of passing, it produces energy which is store it in a supercapacitor or in a rechargeable battery. The concept can be applied to busy roads, and to high-frequented rail networks and it can work with street and road lighting, information panels and monitoring devices.

  1. Study of low-frequency-acoustic- and seismic-wave energy propagation on the shelf

    NASA Astrophysics Data System (ADS)

    Rutenko, A. N.; Manul'chev, D. S.; Solov'ev, A. A.

    2013-05-01

    The paper presents the results of field and numerical studies on the features of low-frequency-acoustic- and seismic-wave energy propagation on the shelf of the Sea of Japan. Measurements were conducted with the Mollusk-07 autonomous vertical acousto-hydrophysical measurement system, an electromagnetic low-frequency resonance emitter, and a pulsed pneumoemitter lowered from the ship, as well as a shore-based resonance seismoemitter.

  2. Energy monitoring and analysis during deformation of bedded-sandstone: use of acoustic emission.

    PubMed

    Wasantha, P L P; Ranjith, P G; Shao, S S

    2014-01-01

    This paper investigates the mechanical behaviour and energy releasing characteristics of bedded-sandstone with bedding layers in different orientations, under uniaxial compression. Cylindrical sandstone specimens (54 mm diameter and 108 mm height) with bedding layers inclined at angles of 10°, 20°, 35°, 55°, and 83° to the minor principal stress direction, were produced to perform a series of Uniaxial Compressive Strength (UCS) tests. One of the two identical sample sets was fully-saturated with water before testing and the other set was tested under dry conditions. An acoustic emission system was employed in all the testing to monitor the acoustic energy release during the whole deformation process of specimens. From the test results, the critical joint orientation was observed as 55° for both dry and saturated samples and the peak-strength losses due to water were 15.56%, 20.06%, 13.5%, 13.2%, and 13.52% for the bedding orientations 10°, 20°, 35°, 55°, and 83°, respectively. The failure mechanisms for the specimens with bedding layers in 10°, 20° orientations showed splitting type failure, while the specimens with bedding layers in 55°, 83° orientations were failed by sliding along a weaker bedding layer. The failure mechanism for the specimens with bedding layers in 35° orientation showed a mixed failure mode of both splitting and sliding types. Analysis of the acoustic energy, captured from the acoustic emission detection system, revealed that the acoustic energy release is considerably higher in dry specimens than that of the saturated specimens at any bedding orientation. In addition, higher energy release was observed for specimens with bedding layers oriented in shallow angles (which were undergoing splitting type failures), whereas specimens with steeply oriented bedding layers (which were undergoing sliding type failures) showed a comparatively less energy release under both dry and saturated conditions. Moreover, a considerable amount of

  3. Investigating Bandgap Energies, Materials, and Design of Light-Emitting Diodes

    ERIC Educational Resources Information Center

    Wagner, Eugene P., II

    2016-01-01

    A student laboratory experiment to investigate the intrinsic and extrinsic bandgaps, dopant materials, and diode design in light-emitting diodes (LEDs) is presented. The LED intrinsic bandgap is determined by passing a small constant current through the diode and recording the junction voltage variation with temperature. A second visible…

  4. Long-Range Energy Transfer and Singlet-Exciton Migration in Working Organic Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Ingram, Grayson L.; Nguyen, Carmen; Lu, Zheng-Hong

    2016-06-01

    Rapid industrialization of organic light-emitting devices for flat-panel displays and solid-state lighting makes a deep understanding of device physics more desirable than ever. Developing reliable experimental techniques to measure fundamental physical properties such as exciton diffusion lengths is a vital part of developing device physics. In this paper, we present a study of exciton diffusion and long-range energy transfer in working organic light-emitting devices, and a study of the interplay between these two tangled processes through both experimental probes and simulations. With the inclusion of multiple factors including long-range energy transfer, exciton boundary conditions, and the finite width of the exciton generation zone, we quantify exciton migration based on emission characteristics from rubrene sensing layers placed in working organic light-emitting devices. This comprehensive analysis is found to be essential to accurately measuring exciton diffusion length, and in the present case the measured singlet-exciton diffusion length in the archetype material 4' -bis(carbazol-9-yl)biphenyl is 4.3 ±0.3 nm with a corresponding diffusivity of (2.6 ±0.3 )×10-4 cm2/s .

  5. Note: High-efficiency broadband acoustic energy harvesting using Helmholtz resonator and dual piezoelectric cantilever beams

    SciTech Connect

    Yang, Aichao; Li, Ping Wen, Yumei; Lu, Caijiang; Peng, Xiao; He, Wei; Zhang, Jitao; Wang, Decai; Yang, Feng

    2014-06-15

    A high-efficiency broadband acoustic energy harvester consisting of a compliant-top-plate Helmholtz resonator (HR) and dual piezoelectric cantilever beams is proposed. Due to the high mechanical quality factor of beams and the strong multimode coupling of HR cavity, top plate and beams, the high efficiency in a broad bandwidth is obtained. Experiment exhibits that the proposed harvester at 170–206 Hz has 28–188 times higher efficiency than the conventional harvester using a HR with a piezoelectric composite diaphragm. For input acoustic pressure of 2.0 Pa, the proposed harvester exhibits 0.137–1.43 mW output power corresponding to 0.035–0.36 μW cm{sup −3} volume power density at 170–206 Hz.

  6. Note: High-efficiency broadband acoustic energy harvesting using Helmholtz resonator and dual piezoelectric cantilever beams.

    PubMed

    Yang, Aichao; Li, Ping; Wen, Yumei; Lu, Caijiang; Peng, Xiao; He, Wei; Zhang, Jitao; Wang, Decai; Yang, Feng

    2014-06-01

    A high-efficiency broadband acoustic energy harvester consisting of a compliant-top-plate Helmholtz resonator (HR) and dual piezoelectric cantilever beams is proposed. Due to the high mechanical quality factor of beams and the strong multimode coupling of HR cavity, top plate and beams, the high efficiency in a broad bandwidth is obtained. Experiment exhibits that the proposed harvester at 170-206 Hz has 28-188 times higher efficiency than the conventional harvester using a HR with a piezoelectric composite diaphragm. For input acoustic pressure of 2.0 Pa, the proposed harvester exhibits 0.137-1.43 mW output power corresponding to 0.035-0.36 μW cm(-3) volume power density at 170-206 Hz. PMID:24985867

  7. Note: High-efficiency broadband acoustic energy harvesting using Helmholtz resonator and dual piezoelectric cantilever beams

    NASA Astrophysics Data System (ADS)

    Yang, Aichao; Li, Ping; Wen, Yumei; Lu, Caijiang; Peng, Xiao; He, Wei; Zhang, Jitao; Wang, Decai; Yang, Feng

    2014-06-01

    A high-efficiency broadband acoustic energy harvester consisting of a compliant-top-plate Helmholtz resonator (HR) and dual piezoelectric cantilever beams is proposed. Due to the high mechanical quality factor of beams and the strong multimode coupling of HR cavity, top plate and beams, the high efficiency in a broad bandwidth is obtained. Experiment exhibits that the proposed harvester at 170-206 Hz has 28-188 times higher efficiency than the conventional harvester using a HR with a piezoelectric composite diaphragm. For input acoustic pressure of 2.0 Pa, the proposed harvester exhibits 0.137-1.43 mW output power corresponding to 0.035-0.36 μW cm-3 volume power density at 170-206 Hz.

  8. Effective parameters in beam acoustic metamaterials based on energy band structures

    NASA Astrophysics Data System (ADS)

    Jing, Li; Wu, Jiu Hui; Guan, Dong; Hou, Mingming; Kuan, Lu; Shen, Li

    2016-07-01

    We present a method to calculate the effective material parameters of beam acoustic metamaterials. The effective material parameters of a periodic beam are calculated as an example. The dispersion relations and energy band structures of this beam are calculated. Subsequently, the effective material parameters of the beam are investigated by using the energy band structures. Then, the modal analysis and transmission properties of the beams with finite cells are simulated in order to confirm the correctness of effective approximation. The results show that the periodic beam can be equivalent to the homogeneous beam with dynamic effective material parameters in passband.

  9. Directional Electrostatic Accretion Process Employing Acoustic Droplet Formation

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard (Inventor)

    1998-01-01

    The present invention is directed to an apparatus for manufacturing a free standing solid metal part. In the present invention, metal droplets are ejected in a nozzleless fashion from a free surface pool of molten metal by applying focused acoustic radiation pressure. The acoustic radiation pressure is produced by high intensity acoustic tone bursts emitted from an acoustic source positioned at the bottom of the pool which directs the acoustic energy at the pool surface. The metal droplets are electrostatically charged so their trajectory can be controlled by electric fields that guide the droplets to predetermined points on a target. The droplets impinge upon the target and solidify with the target material. The accretion of the electrostatically directed solidified droplets forms the free standing metal part.

  10. Measurement of the Spectral Distribution of Low Energy Electrons emitted as a result of MVV Auger Transition in Cu(100)

    NASA Astrophysics Data System (ADS)

    Satyal, Suman; Joglekar, P. V.; Shastry, K.; Weiss, A. H.; Hulbert, S. L.

    2011-10-01

    Auger Photoelectron Coincidence Spectroscopy (APECS) was used to investigate the physics of the Low Energy tail (LET) region of the Auger spectrum of a Cu (100) sample. A beam of 200eV photons was incident on the sample and two Cylindrical Mirror Analyzers (CMA's) were used to select the energy of electrons emitted from the sample. An APECS spectra was obtained with one of the CMA's fixed at the energy 136.25eV, which corresponds to the core photoemission peak. The APECS spectra contains the contributions from electrons excited by the MVV Auger transition plus a background due to true coincidences between photo-emitted valence band electrons that undergo inelastic scattering and transfer part of their energy with other valence electrons. Coincidence measurements were made with the fixed analyzer set at various energies between the core and the valence band. These measurements were used to obtain an estimate of the background due to the inelastically scattered valence band electrons.

  11. Ultralow frequency acoustic bandgap and vibration energy recovery in tetragonal folding beam phononic crystal

    NASA Astrophysics Data System (ADS)

    Gao, Nansha; Wu, Jiu Hui; Yu, Lie; Hou, Hong

    2016-06-01

    This paper investigates ultralow frequency acoustic properties and energy recovery of tetragonal folding beam phononic crystal (TFBPC) and its complementary structure. The dispersion curve relationships, transmission spectra and displacement fields of the eigenmodes are studied with FEA in detail. Compared with the traditional three layer phononic crystal (PC) structure, this structure proposed in this paper not only unfold bandgaps (BGs) in lower frequency range (below 300 Hz), but also has lighter weight because of beam structural cracks. We analyze the relevant physical mechanism behind this phenomenon, and discuss the effects of the tetragonal folding beam geometric parameters on band structure maps. FEM proves that the multi-cell structures with different arrangements have different acoustic BGs when compared with single cell structure. Harmonic frequency response and piezoelectric properties of TFBPC are specifically analyzed. The results confirm that this structure does have the recovery ability for low frequency vibration energy in environment. These conclusions in this paper could be indispensable to PC practical applications such as BG tuning and could be applied in portable devices, wireless sensor, micro-electro mechanical systems which can recycle energy from vibration environment as its own energy supply.

  12. Enhancing the dynamic range of targeted energy transfer in acoustics using several nonlinear membrane absorbers

    NASA Astrophysics Data System (ADS)

    Bellet, R.; Cochelin, B.; Côte, R.; Mattei, P.-O.

    2012-12-01

    In order to enhance the robustness and the energy range of efficiency of targeted energy transfer (TET) phenomena in acoustics, we discuss in this paper about the use of multiple nonlinear membrane absorbers (called nonlinear energy sinks or NES) placed in parallel. We show this way, mainly thanks to an experimental set-up with two membranes, that the different absorbers have additional effects that extend the efficiency and the possibilities of observation of TET. More precisely, we present the different behavior of the system under sinusoidal forcing and free oscillations, characterizing the phenomena for all input energies. The frequency responses are also presented, showing successive clipping of the original resonance peak of the system, and strongly modulated regimes (SMR). A model is finally used to generalize these results to more than two NES and to simulate the case of several very similar membranes in parallel which shows how to extend the existence zone of TET.

  13. Even-odd effects in Z and N distributions of fragments emitted at intermediate energies

    SciTech Connect

    Lombardo, I.; Lanzalone, G.; Agodi, C.; Amorini, F.; Anzalone, A.; Han, J.; Maiolino, C.; Auditore, L.; Loria, D.; Trifiro, A.; Trimarchi, M.; Berceanu, I.; Cardella, G.; De Filippo, E.; Pagano, A.; Papa, M.; Pirrone, S.; Cavallaro, S.; Porto, F.; Rizzo, F.

    2011-08-15

    Even-odd effects in Z and N distributions of light fragments emitted at forward angles in nuclear collisions {sup 40}Ca + {sup 40}Ca, {sup 40}Ca + {sup 48}Ca, and {sup 48}Ca + {sup 48}Ca at 25 MeV/nucleon and identified in charge and mass with the Chimera multidetector have been analyzed. The amplitude of even-odd staggering effects seems to be related to the neutron to proton ratio N/Z of the entrance channels. A qualitative explanation of this effect, taking into account the deexcitation phase of primary excited fragments, is discussed.

  14. Detecting special nuclear materials in containers using high-energy gamma rays emitted by fission products

    DOEpatents

    Norman, Eric B.; Prussin, Stanley G.

    2007-10-02

    A method and a system for detecting the presence of special nuclear materials in a container. The system and its method include irradiating the container with an energetic beam, so as to induce a fission in the special nuclear materials, detecting the gamma rays that are emitted from the fission products formed by the fission, to produce a detector signal, comparing the detector signal with a threshold value to form a comparison, and detecting the presence of the special nuclear materials using the comparison.

  15. An Enhanced Energy Balanced Data Transmission Protocol for Underwater Acoustic Sensor Networks

    PubMed Central

    Javaid, Nadeem; Shah, Mehreen; Ahmad, Ashfaq; Imran, Muhammad; Khan, Majid Iqbal; Vasilakos, Athanasios V.

    2016-01-01

    This paper presents two new energy balanced routing protocols for Underwater Acoustic Sensor Networks (UASNs); Efficient and Balanced Energy consumption Technique (EBET) and Enhanced EBET (EEBET). The first proposed protocol avoids direct transmission over long distance to save sufficient amount of energy consumed in the routing process. The second protocol overcomes the deficiencies in both Balanced Transmission Mechanism (BTM) and EBET techniques. EBET selects relay node on the basis of optimal distance threshold which leads to network lifetime prolongation. The initial energy of each sensor node is divided into energy levels for balanced energy consumption. Selection of high energy level node within transmission range avoids long distance direct data transmission. The EEBET incorporates depth threshold to minimize the number of hops between source node and sink while eradicating backward data transmissions. The EBET technique balances energy consumption within successive ring sectors, while, EEBET balances energy consumption of the entire network. In EEBET, optimum number of energy levels are also calculated to further enhance the network lifetime. Effectiveness of the proposed schemes is validated through simulations where these are compared with two existing routing protocols in terms of network lifetime, transmission loss, and throughput. The simulations are conducted under different network radii and varied number of nodes. PMID:27070605

  16. An Enhanced Energy Balanced Data Transmission Protocol for Underwater Acoustic Sensor Networks.

    PubMed

    Javaid, Nadeem; Shah, Mehreen; Ahmad, Ashfaq; Imran, Muhammad; Khan, Majid Iqbal; Vasilakos, Athanasios V

    2016-01-01

    This paper presents two new energy balanced routing protocols for Underwater Acoustic Sensor Networks (UASNs); Efficient and Balanced Energy consumption Technique (EBET) and Enhanced EBET (EEBET). The first proposed protocol avoids direct transmission over long distance to save sufficient amount of energy consumed in the routing process. The second protocol overcomes the deficiencies in both Balanced Transmission Mechanism (BTM) and EBET techniques. EBET selects relay node on the basis of optimal distance threshold which leads to network lifetime prolongation. The initial energy of each sensor node is divided into energy levels for balanced energy consumption. Selection of high energy level node within transmission range avoids long distance direct data transmission. The EEBET incorporates depth threshold to minimize the number of hops between source node and sink while eradicating backward data transmissions. The EBET technique balances energy consumption within successive ring sectors, while, EEBET balances energy consumption of the entire network. In EEBET, optimum number of energy levels are also calculated to further enhance the network lifetime. Effectiveness of the proposed schemes is validated through simulations where these are compared with two existing routing protocols in terms of network lifetime, transmission loss, and throughput. The simulations are conducted under different network radii and varied number of nodes. PMID:27070605

  17. The source of solar high-frequency acoustic modes - Theoretical expectations

    NASA Technical Reports Server (NTRS)

    Brown, Timothy M.

    1991-01-01

    The source exciting the solar p-modes is likely to be acoustic noise generated in the top part of the sun's convection zone. If so, then simple arguments suggest that most of the emitted energy may come from rare localized events that are well separated from one another in space and time. This note describes the acoustic emission that would be expected from such events, based on a ray-theory analysis. Most of the acoustic energy is found to emerge very close to the source, so that observations to identify emission events will require high spatial resolution.

  18. Very High Brightness Quantum Dot Light-Emitting Devices via Enhanced Energy Transfer from a Phosphorescent Sensitizer.

    PubMed

    Zamani Siboni, Hossein; Sadeghimakki, Bahareh; Sivoththaman, Siva; Aziz, Hany

    2015-11-25

    We demonstrate very efficient and bright quantum dot light-emitting devices (QDLEDs) with the use of a phosphorescent sensitizer and a thermal annealing step. Utilizing CdSe/CdS core/shell quantum dots with 560 nm emission peak, bis(4,6-difluorophenylpyridinatoN,C2) picolinatoiridium as a sensitizer, and thermal annealing at 50 °C for 30 min, green-emitting QDLEDs with a maximum current efficiency of 23.9 cd/A, a power efficiency of 31 lm/W, and a brightness of 65,000 cd/m(2) are demonstrated. The high efficiency and brightness are attributed to annealing-induced enhancements in both the Forster resonance energy transfer (FRET) process from the phosphorescent energy donor to the QD acceptor and hole transport across the device. The FRET enhancement is attributed to annealing-induced diffusion of the phosphorescent material molecules from the sensitizer layer into the QD layer, which results in a shorter donor-acceptor distance. We also find, quite interestingly, that FRET to a QD acceptor is strongly influenced by the QD size, and is generally less efficient to QDs with larger sizes despite their narrower bandgaps. PMID:26556102

  19. Generation and control of pressure pulsations emitted from centrifugal pumps: A review

    SciTech Connect

    Rzentkowski, G.

    1996-12-01

    Pressure pulsations emitted by centrifugal pumps may strongly interact with a piping system, leading to excessive vibration and alternating stresses beyond endurance limits. Several cases of this nature were reported, especially in chemical, petro-chemical and power generation industries, causing costly repairs and loss of power. In the past, research attention was primary focused on corrective actions involving the design and installation of piping elements to absorb acoustic energy emitted by pumps. Currently, more emphasis is placed on developing analytical tools to predict piping system acoustics and avoid undesirable resonance effects. Little attention has been directed towards preventive actions, leading to a better understanding of pumps as an acoustic source. This paper provides an overview of the underlying excitation mechanisms and modelling techniques, and explores the role of pump design parameters in controlling pressure pulsations. The application here is to primary heat transport system of CANDU reactor.

  20. Experimental analysis of the relationship between reverberant acoustic intensity and energy density inside long rooms.

    PubMed

    Visentin, Chiara; Prodi, Nicola; Valeau, Vincent; Picaut, Judicaël

    2015-07-01

    In this paper, the validity of the Fick's law of diffusion in room acoustics is experimentally investigated inside long rooms. The room-acoustics diffusion model relies on Fick's law stating a proportionality relationship between sound intensity and energy density gradient inside a room through a constant diffusion coefficient. This relationship is investigated in the stationary state for the particular case of long rooms with different amounts of boundary scattering. Measurements were performed inside a 1:16 scale model, using a p-u sound intensity probe (calibrated with digital filters) to collect concurrent data in terms of sound pressure and axial velocity components. Then for each receiver position, sound intensity and energy density gradient were derived. The results show that inside long rooms the diffusion coefficient is not a constant but increases with the distance from the source with a slope depending on the scattering coefficient of the walls. Numerical simulations of the enclosures were performed too by using a sound particle-tracing code; a substantial agreement with the experimental findings is observed. The results imply that for such long enclosures, the diffusion model should consider a space-varying diffusion coefficient to be more consistent with real phenomena. PMID:26233018

  1. Lightweight Filter Architecture for Energy Efficient Mobile Vehicle Localization Based on a Distributed Acoustic Sensor Network

    PubMed Central

    Kim, Keonwook

    2013-01-01

    The generic properties of an acoustic signal provide numerous benefits for localization by applying energy-based methods over a deployed wireless sensor network (WSN). However, the signal generated by a stationary target utilizes a significant amount of bandwidth and power in the system without providing further position information. For vehicle localization, this paper proposes a novel proximity velocity vector estimator (PVVE) node architecture in order to capture the energy from a moving vehicle and reject the signal from motionless automobiles around the WSN node. A cascade structure between analog envelope detector and digital exponential smoothing filter presents the velocity vector-sensitive output with low analog circuit and digital computation complexity. The optimal parameters in the exponential smoothing filter are obtained by analytical and mathematical methods for maximum variation over the vehicle speed. For stationary targets, the derived simulation based on the acoustic field parameters demonstrates that the system significantly reduces the communication requirements with low complexity and can be expected to extend the operation time considerably. PMID:23979482

  2. Lightweight filter architecture for energy efficient mobile vehicle localization based on a distributed acoustic sensor network.

    PubMed

    Kim, Keonwook

    2013-01-01

    The generic properties of an acoustic signal provide numerous benefits for localization by applying energy-based methods over a deployed wireless sensor network (WSN). However, the signal generated by a stationary target utilizes a significant amount of bandwidth and power in the system without providing further position information. For vehicle localization, this paper proposes a novel proximity velocity vector estimator (PVVE) node architecture in order to capture the energy from a moving vehicle and reject the signal from motionless automobiles around the WSN node. A cascade structure between analog envelope detector and digital exponential smoothing filter presents the velocity vector-sensitive output with low analog circuit and digital computation complexity. The optimal parameters in the exponential smoothing filter are obtained by analytical and mathematical methods for maximum variation over the vehicle speed. For stationary targets, the derived simulation based on the acoustic field parameters demonstrates that the system significantly reduces the communication requirements with low complexity and can be expected to extend the operation time considerably. PMID:23979482

  3. Energy balance of acoustic gravity waves above the polar caps according to the data of satellite measurements

    NASA Astrophysics Data System (ADS)

    Fedorenko, A. K.

    2010-02-01

    Wave disturbances of the Neutral Atmosphere above the polar caps are studied based on the Dynamic Explorer 2 satellite measurements. The characteristic spatial scales of these disturbances are 500— 600 km. Based on an analysis of the synchronous variations in different parameters, these disturbances were interpreted as propagating acoustic gravity waves (AGWs). The mass-spectrometer measurements of concentrations of individual atmospheric gases made it possible to determine the following AGW components: density of the acoustic compression, thermobaric, and average kinetic energies. It has been found out that the average (during the period) densities of the acoustic and thermobaric energies are approximately equal for polar AGWs. The results indicate that the contribution of these waves to the energy of the polar upper atmosphere is considerable.

  4. Nano-light-emitting-diodes based on InGaN mesoscopic structures for energy saving optoelectronics

    NASA Astrophysics Data System (ADS)

    Mikulics, M.; Winden, A.; Marso, M.; Moonshiram, A.; Lüth, H.; Grützmacher, D.; Hardtdegen, H.

    2016-07-01

    Vertically integrated III-nitride based nano-LEDs (light emitting diodes) were designed and fabricated for operation in the telecommunication wavelength range in the (p-GaN/InGaN/n-GaN/sapphire) material system. The band edge luminescence energy of the nano-LEDs could be engineered by tuning the composition and size of the InGaN mesoscopic structures. Narrow band edge photoluminescence and electroluminescence were observed. Our mesoscopic InGaN structures (depending on diameter) feature a very low power consumption in the range between 2 nW and 30 nW. The suitability of the technological process for the long-term operation of LEDs is demonstrated by reliability measurements. The optical and electrical characterization presented show strong potential for future low energy consumption optoelectronics.

  5. Mn-doped nanocrystals in light-emitting diodes: Energy-transfer to obtain electroluminescence from quantum dots

    NASA Astrophysics Data System (ADS)

    Rath, Arup K.; Bhaumik, Saikat; Pal, Amlan J.

    2010-09-01

    We fabricate light-emitting diodes (LEDs) based on Mn-doped ZnS nanocrystals along with hole-transporting N ,N' bis(3-methylphenyl)-N ,N'-diphenyl-benzidine (TPD). With Mn-doping, ZnS nanostructures exhibit a strong photoluminescence. The LEDs exhibit electroluminescence (EL) from Mn-doped ZnS quantum dots and TPD. In order to open up channels for energy-transfer from TPD to quantum dots and to achieve EL from only the nanoparticles, we grow core-shell nanoparticles with Mn-doped ZnS in the core and CdS as the shell layer. Excitons formed in TPD can now transfer their energy directly to the shell-layer to yield EL from only the nanoparticles.

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

    NASA Astrophysics Data System (ADS)

    Summers, Jason Erik

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

  7. Energy balanced strategies for maximizing the lifetime of sparsely deployed underwater acoustic sensor networks.

    PubMed

    Luo, Hanjiang; Guo, Zhongwen; Wu, Kaishun; Hong, Feng; Feng, Yuan

    2009-01-01

    Underwater acoustic sensor networks (UWA-SNs) are envisioned to perform monitoring tasks over the large portion of the world covered by oceans. Due to economics and the large area of the ocean, UWA-SNs are mainly sparsely deployed networks nowadays. The limited battery resources is a big challenge for the deployment of such long-term sensor networks. Unbalanced battery energy consumption will lead to early energy depletion of nodes, which partitions the whole networks and impairs the integrity of the monitoring datasets or even results in the collapse of the entire networks. On the contrary, balanced energy dissipation of nodes can prolong the lifetime of such networks. In this paper, we focus on the energy balance dissipation problem of two types of sparsely deployed UWA-SNs: underwater moored monitoring systems and sparsely deployed two-dimensional UWA-SNs. We first analyze the reasons of unbalanced energy consumption in such networks, then we propose two energy balanced strategies to maximize the lifetime of networks both in shallow and deep water. Finally, we evaluate our methods by simulations and the results show that the two strategies can achieve balanced energy consumption per node while at the same time prolong the networks lifetime. PMID:22399970

  8. Efficient Structure Resonance Energy Transfer from Microwaves to Confined Acoustic Vibrations in Viruses

    NASA Astrophysics Data System (ADS)

    Yang, Szu-Chi; Lin, Huan-Chun; Liu, Tzu-Ming; Lu, Jen-Tang; Hung, Wan-Ting; Huang, Yu-Ru; Tsai, Yi-Chun; Kao, Chuan-Liang; Chen, Shih-Yuan; Sun, Chi-Kuang

    2015-12-01

    Virus is known to resonate in the confined-acoustic dipolar mode with microwave of the same frequency. However this effect was not considered in previous virus-microwave interaction studies and microwave-based virus epidemic prevention. Here we show that this structure-resonant energy transfer effect from microwaves to virus can be efficient enough so that airborne virus was inactivated with reasonable microwave power density safe for the open public. We demonstrate this effect by measuring the residual viral infectivity of influenza A virus after illuminating microwaves with different frequencies and powers. We also established a theoretical model to estimate the microwaves power threshold for virus inactivation and good agreement with experiments was obtained. Such structure-resonant energy transfer induced inactivation is mainly through physically fracturing the virus structure, which was confirmed by real-time reverse transcription polymerase chain reaction. These results provide a pathway toward establishing a new epidemic prevention strategy in open public for airborne virus.

  9. RAPID COMMUNICATION: Traceability of acoustic emission measurements using energy calibration methods

    NASA Astrophysics Data System (ADS)

    Yan, T.; Jones, B. E.

    2000-11-01

    Passive acoustic emission (AE) methods are becoming useful tools for integrity assessment of structures, monitoring of industrial processes and machines, and materials characterization. Unfortunately, there are no measurement standards for estimating the absolute strength of the AE sources. The lack of standardization makes it very difficult to compare the results obtained in different laboratories or on different structures, and to obtain meaningful repeatability of measurements. Therefore, current methods only give a qualitative rather than quantitative indication of the change of state of structure or process. This communication outlines a way of calibrating AE transducer systems in situ using a pulsed-laser-generated thermoelastic AE energy source or a bouncing-ball-generated elastic impact AE energy source. The methods presented here should enable traceable measurement standards to be established for AE.

  10. Contactless ultrasonic energy transfer for wireless systems: acoustic-piezoelectric structure interaction modeling and performance enhancement

    NASA Astrophysics Data System (ADS)

    Shahab, S.; Erturk, A.

    2014-12-01

    There are several applications of wireless electronic components with little or no ambient energy available to harvest, yet wireless battery charging for such systems is still of great interest. Example applications range from biomedical implants to sensors located in hazardous environments. Energy transfer based on the propagation of acoustic waves at ultrasonic frequencies is a recently explored alternative that offers increased transmitter-receiver distance, reduced loss and the elimination of electromagnetic fields. As this research area receives growing attention, there is an increased need for fully coupled model development to quantify the energy transfer characteristics, with a focus on the transmitter, receiver, medium, geometric and material parameters. We present multiphysics modeling and case studies of the contactless ultrasonic energy transfer for wireless electronic components submerged in fluid. The source is a pulsating sphere, and the receiver is a piezoelectric bar operating in the 33-mode of piezoelectricity with a fundamental resonance frequency above the audible frequency range. The goal is to quantify the electrical power delivered to the load (connected to the receiver) in terms of the source strength. Both the analytical and finite element models have been developed for the resulting acoustic-piezoelectric structure interaction problem. Resistive and resistive-inductive electrical loading cases are presented, and optimality conditions are discussed. Broadband power transfer is achieved by optimal resistive-reactive load tuning for performance enhancement and frequency-wise robustness. Significant enhancement of the power output is reported due to the use of a hard piezoelectric receiver (PZT-8) instead of a soft counterpart (PZT-5H) as a result of reduced material damping. The analytical multiphysics modeling approach given in this work can be used to predict and optimize the coupled system dynamics with very good accuracy and dramatically

  11. Photoluminescence Properties and Energy Transfer in a Novel Yellow Emitting Phosphor GdTaO4: Dy3+.

    PubMed

    Zhang, Hijuan; Tan, Xinyu; Wang, Yuhua

    2016-04-01

    The phosphor Dy3+ doped M type gadolinium orthotantalate GdTaO4 was prepared successfully by traditional solid state reaction and the photoluminescence of GdTaO4: xDy3+ (0.01 ≤ x ≤ 0.10) has been investigated under ultraviolet and vacuum ultraviolet excitation. In the excitation spectra of GdTaO4: Dy3+, the overlap appears between the host lattice excitation, the excitation lines of Gd3+ and the f-f transitions of Dy3+, which indicates that the energy transfer could occur from the host to the Dy3+ ions. In the emission spectra of the samples, the intense emissions of Dy3+ have been expectably revealed both upon excitation at 365 nm and 147 nm. And the chromaticity coordinates of GdTaO4: xDy3+ have been correspondingly calculated. The results indicate that GdTaO4: Dy3+ would be a novel yellow emitting phosphor applied in light emitting diodes (LEDs), plasma display panels (PDPs) and mercury-free fluorescent tubes. PMID:27451754

  12. Investigation of acoustic cavitation energy in a large-scale sonoreactor.

    PubMed

    Son, Younggyu; Lim, Myunghee; Khim, Jeehyeong

    2009-04-01

    Acoustic cavitation energy distributions were investigated for various frequencies such as 35, 72, 110 and 170 kHz in a large-scale sonoreactor. The energy analyses were conducted in three-dimensions and the highest and most stable cavitation energy distribution was obtained not in 35 kHz but in 72 kHz. However, the half-cavitation-energy distance was larger in the case of 35 kHz ultrasound than in the case of 72 kHz, demonstrating that cavitation energy for one cycle was higher for a lower frequency. This discrepancy was due to the large surface area of the cavitation-energy-meter probe. In addition, 110 and 170 kHz ultrasound showed a very low and poor cavitation energy distribution. Therefore larger input power was required to optimize the use of higher frequency ultrasound in the sonoreactor with long-irradiation distance. The relationship between cavitation energy and sonochemical efficiency using potassium iodide (KI) dosimetry was best fitted quadratically. From 7.77 x 10(-10) to 4.42 x 10(-9)mol/J of sonochemical efficiency was evaluated for the cavitation energy from 31.76 to 103. 67 W. In addition, the cavitation energy attenuation was estimated under the assumption that cavitation energy measured in this study would be equivalent to sound intensity, resulting in 0.10, 0.18 and 2.44 m(-1) of the attenuation coefficient (alpha) for 35, 72 and 110 kHz, respectively. Furthermore, alpha/(frequency)(2) was not constant, as some previous studies have suggested. PMID:19144557

  13. Acoustic transducer for nuclear reactor monitoring

    DOEpatents

    Ahlgren, Frederic F.; Scott, Paul F.

    1977-01-01

    A transducer to monitor a parameter and produce an acoustic signal from which the monitored parameter can be recovered. The transducer comprises a modified Galton whistle which emits a narrow band acoustic signal having a frequency dependent upon the parameter being monitored, such as the temperature of the cooling media of a nuclear reactor. Multiple locations within a reactor are monitored simultaneously by a remote acoustic receiver by providing a plurality of transducers each designed so that the acoustic signal it emits has a frequency distinct from the frequencies of signals emitted by the other transducers, whereby each signal can be unambiguously related to a particular transducer.

  14. An experimentally validated contactless acoustic energy transfer model with resistive-reactive electrical loading

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    This paper investigates analytical modeling and experimental validation of Ultrasonic Acoustic Energy Transfer (UAET) for low-power electricity transfer to exploit in wireless applications ranging from medical implants to underwater sensor systems. A piezoelectric receiver bar is excited by incident acoustic waves originating from a source of known strength located at a specific distance from the receiver. The receiver is a free-free piezoelectric cylinder operating in the 33- mode of piezoelectricity with a fundamental resonance frequency above the audible frequency range. In order to extract the electrical power output, the piezoelectric receiver bar is shunted to a generalized resistive-reactive circuit. The goal is to quantify the electrical power delivered to the load (connected to the receiver) in terms of the source strength. Experimental validations are presented along with parameter optimization studies. Sensitivity of the electrical power output to the excitation frequency in the neighborhood of the receiver's underwater resonance frequency, source-to-receiver distance, and source-strength level are reported. Resistive and resistive-reactive electrical loading cases are discussed for performance enhancement and frequency-wise robustness. Simulations and experiments reveal that the presented multiphysics analytical model for UAET can be used to predict the coupled system dynamics with very good accuracy.

  15. Laser Imaging of Airborne Acoustic Emission by Nonlinear Defects

    NASA Astrophysics Data System (ADS)

    Solodov, Igor; Döring, Daniel; Busse, Gerd

    2008-06-01

    Strongly nonlinear vibrations of near-surface fractured defects driven by an elastic wave radiate acoustic energy into adjacent air in a wide frequency range. The variations of pressure in the emitted airborne waves change the refractive index of air thus providing an acoustooptic interaction with a collimated laser beam. Such an air-coupled vibrometry (ACV) is proposed for detecting and imaging of acoustic radiation of nonlinear spectral components by cracked defects. The photoelastic relation in air is used to derive induced phase modulation of laser light in the heterodyne interferometer setup. The sensitivity of the scanning ACV to different spatial components of the acoustic radiation is analyzed. The animated airborne emission patterns are visualized for the higher harmonic and frequency mixing fields radiated by planar defects. The results confirm a high localization of the nonlinear acoustic emission around the defects and complicated directivity patterns appreciably different from those observed for fundamental frequencies.

  16. 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.

  17. Characterization of Low-Energy Photon-Emitting Brachytherapy Sources with Modified Strengths for Applications in Focal Therapy

    NASA Astrophysics Data System (ADS)

    Reed, Joshua L.

    Permanent implants of low-energy photon-emitting brachytherapy sources are used to treat a variety of cancers. Individual source models must be separately characterized due to their unique geometry, materials, and radionuclides, which all influence their dose distributions. Thermoluminescent dosimeters (TLDs) are often used for dose measurements around low-energy photon-emitting brachytherapy sources. TLDs are typically calibrated with higher energy sources such as 60Co, which requires a correction for the change in the response of the TLDs as a function of photon energy. These corrections have historically been based on TLD response to x ray bremsstrahlung spectra instead of to brachytherapy sources themselves. This work determined the TLD intrinsic energy dependence for 125I and 103Pd sources relative to 60Co, which allows for correction of TLD measurements of brachytherapy sources with factors specific to their energy spectra. Traditional brachytherapy sources contain mobile internal components and large amounts of high-Z material such as radio-opaque markers and titanium encapsulations. These all contribute to perturbations and uncertainties in the dose distribution around the source. The CivaString is a new elongated 103Pd brachytherapy source with a fixed internal geometry, polymer encapsulation, and lengths ranging from 1 to 6 cm, which offers advantages over traditional source designs. This work characterized the CivaString source and the results facilitated the formal approval of this source for use in clinical treatments. Additionally, the accuracy of a superposition technique for dose calculation around the sources with lengths >1 cm was verified. Advances in diagnostic techniques are paving the way for focal brachytherapy in which the dose is intentionally modulated throughout the target volume to focus on subvolumes that contain cancer cells. Brachytherapy sources with variable longitudinal strength (VLS) are a promising candidate for use in focal

  18. Acoustic neuroma

    MedlinePlus

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

  19. Application of light-emitting diodes in bioreactors: flashing light effects and energy economy in algal culture (Chlorella pyrenoidosa).

    PubMed

    Matthijs, H C; Balke, H; van Hes, U M; Kroon, B M; Mur, L R; Binot, R A

    1996-04-01

    Light-emitting diodes (LEDs) were used as the sole light source in continuous culture of the green alga Chlorella pyrenoidosa. The LEDs applied show a peak emission at 659 nm with a half-power bandwidth of 30 nm. Selection of this wavelength range, which is optimal for excitation of chlorophylls a and b in their "red" absorption bands makes all photons emitted potentially suitable for photosynthesis. No need for additional supply of blue light was found. A standardized panel with 2 LEDs cm(-2) fully covered one side of the culture vessel. At standard voltage in continuous operation the light output of the diode panel appeared more than sufficient to reach maximal growth. Flash operation (5-mus pulse duration) enables potential use of higher operating voltages which may render up to three times more light output. Flat airlift fermentor-type continuous culture devices were used to estimate steady state growth rates of Chlorella pyrenoidosa as a function of the light flux (micromol photons x m(-2) x s(-1)) and the flashing frequency of the light-emitting diodes (which determines the duration of the dark "off" time between the 5-micros "on" pulses). At the fixed voltage and turbidostat setting applied a 20-kHz frequency, which equals dark periods of 45 mus, still permitted the maximum growth rate to become nearly reached. Lower frequencies fell short of sustaining the maximal growth rate. However, the light flux decrease resulting from lowering of the flash frequency appeared to reduce the observed growth rates less than in the case of a similar flux decrease with light originating from LEDs in continuous operation. Flash application also showed reduction of the quantum requirement for oxygen evolution at defined frequencies. The frequency domain of interest was between 2 and 14 kHz. LEDs may open interesting new perspectives for studies on optimization of mixing in mass algal culture via the possibility of separation of interests in the role of modulation on light

  20. Final Scientific/Technical Report, DE-FG02-08ER41561: "Lyman-alpha Emitting Galaxies at 2Energy"

    SciTech Connect

    Eric Gawiser

    2010-03-19

    Lyman Alpha Emitting (LAE) galaxies are a powerful tracer of large scale structure, making them an excellent probe of baryonic acoustic oscillations, which constrain the expansion history of the universe and hence the nature of the dark energy. The HETDEX Stage III dark energy experiment will utilize LAEs for this purpose, and they are under consideration as a tracer of structure for Stage IV ground- and space-based dark energy missions. Our successful investigation of LAEs at z=2.1 and z=3.1 now provides the best information on the number density and clustering bias of these galaxies over the redshift range that HETDEX will study. Connecting these star-forming galaxies to their host dark matter halos represents a major increase in scientific understanding, as we can now proceed with confidence in studying the spatial distribution of significantly larger samples. Our data also provided an empirical test of the Lyman Alpha Tomography technique, which has proven effective and can now be used to design future experiments to probe dark energy and dark matter properties.

  1. Method and apparatus for sizing and separating warp yarns using acoustical energy

    DOEpatents

    Sheen, Shuh-Haw; Chien, Hual-Te; Raptis, Apostolos C.; Kupperman, David S.

    1998-01-01

    A slashing process for preparing warp yarns for weaving operations including the steps of sizing and/or desizing the yarns in an acoustic resonance box and separating the yarns with a leasing apparatus comprised of a set of acoustically agitated lease rods. The sizing step includes immersing the yarns in a size solution contained in an acoustic resonance box. Acoustic transducers are positioned against the exterior of the box for generating an acoustic pressure field within the size solution. Ultrasonic waves that result from the acoustic pressure field continuously agitate the size solution to effect greater mixing and more uniform application and penetration of the size onto the yarns. The sized yarns are then separated by passing the warp yarns over and under lease rods. Electroacoustic transducers generate acoustic waves along the longitudinal axis of the lease rods, creating a shearing motion on the surface of the rods for splitting the yarns.

  2. Method and apparatus for sizing and separating warp yarns using acoustical energy

    DOEpatents

    Sheen, S.H.; Chien, H.T.; Raptis, A.C.; Kupperman, D.S.

    1998-05-19

    A slashing process is disclosed for preparing warp yarns for weaving operations including the steps of sizing and/or desizing the yarns in an acoustic resonance box and separating the yarns with a leasing apparatus comprised of a set of acoustically agitated lease rods. The sizing step includes immersing the yarns in a size solution contained in an acoustic resonance box. Acoustic transducers are positioned against the exterior of the box for generating an acoustic pressure field within the size solution. Ultrasonic waves that result from the acoustic pressure field continuously agitate the size solution to effect greater mixing and more uniform application and penetration of the size onto the yarns. The sized yarns are then separated by passing the warp yarns over and under lease rods. Electroacoustic transducers generate acoustic waves along the longitudinal axis of the lease rods, creating a shearing motion on the surface of the rods for splitting the yarns. 2 figs.

  3. Measuring acoustic energy density in microchannel acoustophoresis using a simple and rapid light-intensity method.

    PubMed

    Barnkob, Rune; Iranmanesh, Ida; Wiklund, Martin; Bruus, Henrik

    2012-07-01

    We present a simple and rapid method for measuring the acoustic energy density in microchannel acoustophoresis based on light-intensity measurements of a suspension of particles. The method relies on the assumption that each particle in the suspension undergoes single-particle acoustophoresis. It is validated by the single-particle tracking method, and we show by proper re-scaling that the re-scaled light intensity plotted versus re-scaled time falls on a universal curve. The method allows for analysis of moderate-resolution images in the concentration range encountered in typical experiments, and it is an attractive alternative to particle tracking and particle image velocimetry for quantifying acoustophoretic performance in microchannels. PMID:22522812

  4. Vibro-acoustic modelling of aircraft double-walls with structural links using Statistical Energy Analysis

    NASA Astrophysics Data System (ADS)

    Campolina, Bruno L.

    The prediction of aircraft interior noise involves the vibroacoustic modelling of the fuselage with noise control treatments. This structure is composed of a stiffened metallic or composite panel, lined with a thermal and acoustic insulation layer (glass wool), and structurally connected via vibration isolators to a commercial lining panel (trim). The goal of this work aims at tailoring the noise control treatments taking design constraints such as weight and space optimization into account. For this purpose, a representative aircraft double-wall is modelled using the Statistical Energy Analysis (SEA) method. Laboratory excitations such as diffuse acoustic field and point force are addressed and trends are derived for applications under in-flight conditions, considering turbulent boundary layer excitation. The effect of the porous layer compression is firstly addressed. In aeronautical applications, compression can result from the installation of equipment and cables. It is studied analytically and experimentally, using a single panel and a fibrous uniformly compressed over 100% of its surface. When compression increases, a degradation of the transmission loss up to 5 dB for a 50% compression of the porous thickness is observed mainly in the mid-frequency range (around 800 Hz). However, for realistic cases, the effect should be reduced since the compression rate is lower and compression occurs locally. Then the transmission through structural connections between panels is addressed using a four-pole approach that links the force-velocity pair at each side of the connection. The modelling integrates experimental dynamic stiffness of isolators, derived using an adapted test rig. The structural transmission is then experimentally validated and included in the double-wall SEA model as an equivalent coupling loss factor (CLF) between panels. The tested structures being flat, only axial transmission is addressed. Finally, the dominant sound transmission paths are

  5. Quantitative Mapping of Reflected and Emitted Energy Patterns Over a City

    NASA Technical Reports Server (NTRS)

    Luvall, J.; Rickman, D.; Quattrochi, D.; Estes, M.; Arnold, James E. (Technical Monitor)

    2002-01-01

    There are major variations in energy flux within and across the region of a large city. These variations have impacts in disparate areas, such as human health, environmental monitoring and mitigation, and energy consumption. Knowledge of the variations also has utility to urban and regional planners, and climate modelers. The authors have developed a system which permits robust measurement of both the magnitude of the energy flux variation and the absolute value of energy flux over regions of the size of large cites. The technique uses properly acquired and processed multispectral imagery with bands in the visible, near-IR and thermal portions of the electromagnetic spectrum. With proper knowledge of the atmosphere and geometries of acquisition it is possible to compute the energy budget for individual pixels. The reality of this technique is demonstrated using data acquired over Salt Lake City, Utah. The deficiencies in the results emphasize the critical nature of various design and engineering features usually ignored in airborne and satellite imaging systems.

  6. Modeling bistatic spectral measurements of temporally evolving reflected and emitted energy from a distant and receding target

    NASA Astrophysics Data System (ADS)

    Cusumano, Salvatore J.; Fiorino, Steven T.; Bartell, Richard J.; Krizo, Matthew J.; Bailey, William F.; Beauchamp, Rebecca L.; Marciniak, Michael A.

    2011-01-01

    The Air Force Institute of Technology's Center for Directed Energy developed the High Energy Laser End-to-End Operational Simulation (HELEEOS) model in part to quantify the performance variability in laser propagation created by the natural environment during dynamic engagements. As such, HELEEOS includes a fast-calculating, first principles, worldwide surface-to-100 km, atmospheric propagation, and characterization package. This package enables the creation of profiles of temperature, pressure, water vapor content, optical turbulence, atmospheric particulates, and hydrometeors as they relate to line-by-line layer transmission, path, and background radiance at wavelengths from the ultraviolet to radio frequencies. In the current paper an example of a unique high fidelity simulation of a bistatic, time-varying five band multispectral remote observation of energy delivered on a distant and receding test object is presented for noncloudy conditions with aerosols. The multispectral example emphasizes atmospheric effects using HELEEOS, the interaction of the energy and the test object, the observed reflectance, and subsequent hot spot generated. A model of a sensor suite located on the surface is included to collect the diffuse reflected in-band laser radiation and the emitted radiance of the hot spot in four separate and spatially offset midwave infrared and longwave infrared bands. Particular care is taken in modeling the bidirectional reflectance distribution function of the delivered energy/target interaction to account for both the coupling of energy into the test object and the changes in reflectance as a function of temperature. The architecture supports any platform-target-observer geometry, geographic location, season, and time of day, and it provides for correct contributions of the sky-earth background. The simulation accurately models the thermal response, kinetics, turbulence, base disturbance, diffraction, and signal-to-noise ratios.

  7. Measuring the internal energies of species emitted from hypervelocity nanoprojectile impacts on surfaces using recalibrated benzylpyridinium probe ions

    NASA Astrophysics Data System (ADS)

    DeBord, J. Daniel; Verkhoturov, Stanislav V.; Perez, Lisa M.; North, Simon W.; Hall, Michael B.; Schweikert, Emile A.

    2013-06-01

    We present herein a framework for measuring the internal energy distributions of vibrationally excited molecular ions emitted from hypervelocity nanoprojectile impacts on organic surfaces. The experimental portion of this framework is based on the measurement of lifetime distributions of "thermometer" benzylpyridinium ions dissociated within a time of flight mass spectrometer. The theoretical component comprises re-evaluation of the fragmentation energetics of benzylpyridinium ions at the coupled-cluster singles and doubles with perturbative triples level. Vibrational frequencies for the ground and transition states of select molecules are reported, allowing for a full description of vibrational excitations of these molecules via Rice-Ramsperger-Kassel-Marcus unimolecular fragmentation theory. Ultimately, this approach is used to evaluate the internal energy distributions from the measured lifetime distributions. The average internal energies of benzylpyridinium ions measured from 440 keV Au400+4 impacts are found to be relatively low (˜0.24 eV/atom) when compared with keV atomic bombardment of surfaces (1-2 eV/atom).

  8. Distribution of RF energy emitted by mobile phones in anatomical structures of the brain

    NASA Astrophysics Data System (ADS)

    Cardis, E.; Deltour, I.; Mann, S.; Moissonnier, M.; Taki, M.; Varsier, N.; Wake, K.; Wiart, J.

    2008-06-01

    The rapid worldwide increase in mobile phone use in the last decade has generated considerable interest in possible carcinogenic effects of radio frequency (RF). Because exposure to RF from phones is localized, if a risk exists it is likely to be greatest for tumours in regions with greatest energy absorption. The objective of the current paper was to characterize the spatial distribution of RF energy in the brain, using results of measurements made in two laboratories on 110 phones used in Europe or Japan. Most (97-99% depending on frequency) appears to be absorbed in the brain hemisphere on the side where the phone is used, mainly (50-60%) in the temporal lobe. The average relative SARSAR is the specific energy absorption rate i.e. energy absorption rate per unit mass (measured in W kg-1). is highest in the temporal lobe (6-15%, depending on frequency, of the spatial peak SAR in the most exposed region of the brain) and the cerebellum (2-10%) and decreases very rapidly with increasing depth, particularly at higher frequencies. The SAR distribution appears to be fairly similar across phone models, between older and newer phones and between phones with different antenna types and positions. Analyses of risk by location of tumour are therefore important for the interpretation of results of studies of brain tumours in relation to mobile phone use.

  9. Electrical and Optical Measurements of the Bandgap Energy of a Light-Emitting Diode

    ERIC Educational Resources Information Center

    Petit, Matthieu; Michez, Lisa; Raimundo, Jean-Manuel; Dumas, Philippe

    2016-01-01

    Semiconductor materials are at the core of electronics. Most electronic devices are made of semiconductors. The operation of these components is well described by quantum physics which is often a difficult concept for students to understand. One of the intrinsic parameters of semiconductors is their bandgap energy E[subscript g]. In the case of…

  10. Multiplicity and entropy scaling of medium-energy protons emitted in relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Abdelsalam, A.; Kamel, S.; Hafiz, M. E.

    2015-10-01

    The behavior and the properties of medium-energy protons with kinetic energies in the range 26 - 400 MeV is derived from measurements of the particle yields and spectra in the final state of relativistic heavy-ion collisions (16O-AgBr interactions at 60 A and 200 A GeV and 32S-AgBr interactions at 3.7 A and 200 A GeV) and their interpretation in terms of the higher order moments. The multiplicity distributions have been fitted well with the Gaussian distribution function. The data are also compared with the predictions of the modified FRITIOF model, showing that the FRITIOF model does not reproduce the trend and the magnitude of the data. Measurements of the ratio of the variance to the mean show that the production of target fragments at high energies cannot be considered as a statistically independent process. However, the deviation of each multiplicity distribution from a Poisson law provides evidence for correlations. The KNO scaling behavior of two types of scaling (Koba-Nielsen-Olesen (KNO) scaling and Hegyi scaling) functions in terms of the multiplicity distribution is investigated. A simplified universal function has been used in each scaling to display the experimental data. An examination of the relationship between the entropy, the average multiplicity, and the KNO function is performed. Entropy production and subsequent scaling in nucleus-nucleus collisions are carried out by analyzing the experimental data over a wide energy range (Dubna and SPS). Interestingly, the data points corresponding to various energies overlap and fall on a single curve, indicating the presence of a kind of entropy scaling.

  11. Cascade energy transfer versus charge separation in ladder-type oligo(p-phenylene)/ZnO hybrid structures for light-emitting applications

    SciTech Connect

    Bianchi, F.; Sadofev, S.; Schlesinger, R.; Koch, N.; Henneberger, F.; Blumstengel, S.; Kobin, B.; Hecht, S.

    2014-12-08

    Usability of inorganic/organic semiconductor hybrid structures for light-emitting applications can be intrinsically limited by an unfavorable interfacial energy level alignment causing charge separation and nonradiative deactivation. Introducing cascaded energy transfer funneling away the excitation energy from the interface by transfer to a secondary acceptor molecule enables us to overcome this issue. We demonstrate a substantial recovery of the light output along with high inorganic-to-organic exciton conversion rates up to room temperature.

  12. LIMITS TO THE FRACTION OF HIGH-ENERGY PHOTON EMITTING GAMMA-RAY BURSTS

    SciTech Connect

    Akerlof, Carl W.; Zheng, WeiKang

    2013-02-20

    After almost four years of operation, the two instruments on board the Fermi Gamma-ray Space Telescope have shown that the number of gamma-ray bursts (GRBs) with high-energy photon emission above 100 MeV cannot exceed roughly 9% of the total number of all such events, at least at the present detection limits. In a recent paper, we found that GRBs with photons detected in the Large Area Telescope have a surprisingly broad distribution with respect to the observed event photon number. Extrapolation of our empirical fit to numbers of photons below our previous detection limit suggests that the overall rate of such low flux events could be estimated by standard image co-adding techniques. In this case, we have taken advantage of the excellent angular resolution of the Swift mission to provide accurate reference points for 79 GRB events which have eluded any previous correlations with high-energy photons. We find a small but significant signal in the co-added field. Guided by the extrapolated power-law fit previously obtained for the number distribution of GRBs with higher fluxes, the data suggest that only a small fraction of GRBs are sources of high-energy photons.

  13. Problems in Assessment of Wind Energy Potential and Acoustic Noise Distribution when Designing Wind Power Plants

    NASA Astrophysics Data System (ADS)

    Bezrukovs, Valerijs; Bezrukovs, Vladislavs; Levins, Nikolajs

    2011-01-01

    Interest in the use of renewable energy in Latvia is increasing every year. Government support and availability of large unpopulated areas on the coast makes the use of these lands for the placement of large wind power plants (WPP) attractive. The key factors that determine the choice of the location of WPP are reliable information about distribution of the resource of wind energy in this area and the influence of wind turbines on the environment. The paper presents the results of years-long observations on the density fluctuations of wind energy at heights of 10 to 60 m in the area in the Baltic Sea coast in Ventspils and Ainaži. The velocity observations since 2007 have been gathered by measurements complex of the LOGGER 9200 Symphonie type. The results are presented in the form of tables, bar charts and graphs. Extrapolation results of wind velocity and density mean values on heights up to 150 m for the two areas with different terrain types were shown. The distribution of acoustic noise in the vicinity of the WPP was studied and an assessment of its impact on the environment in accordance with the Latvian government requirements was conducted.

  14. Model-independent dark energy equation of state from unanchored baryon acoustic oscillations

    NASA Astrophysics Data System (ADS)

    Evslin, Jarah

    2016-09-01

    Ratios of line of sight baryon acoustic oscillation (BAO) peaks at two redshifts only depend upon the average dark energy equation of states between those redshifts, as the dependence on anchors such as the BAO scale or the Hubble constant is canceled in a ratio. As a result, BAO ratios provide a probe of dark energy which is independent of both the cosmic distance ladder and the early evolution of universe. In this note, we use ratios to demonstrate that the known tension between the Lyman alpha forest BAO measurement and other probes arises entirely from recent (0.57 < z < 2.34) cosmological expansion. Using ratios of the line of sight Lyman alpha forest and BOSS CMASS BAO scales, we show that there is already more than 3 σ tension with the standard ΛCDM cosmological model which implies that either (i) The BOSS Lyman alpha forest measurement of the Hubble parameter was too low as a result of a statistical fluctuation or systematic error or else (ii) the dark energy equation of state falls steeply at high redshift.

  15. Distinguishing interacting dark energy from wCDM with CMB, lensing, and baryon acoustic oscillation data

    NASA Astrophysics Data System (ADS)

    Väliviita, Jussi; Palmgren, Elina

    2015-07-01

    We employ the Planck 2013 CMB temperature anisotropy and lensing data, and baryon acoustic oscillation (BAO) data to constrain a phenomenological wCDM model, where dark matter and dark energy interact. We assume time-dependent equation of state parameter for dark energy, and treat dark matter and dark energy as fluids whose energy-exchange rate is proportional to the dark-matter density. The CMB data alone leave a strong degeneracy between the interaction rate and the physical CDM density parameter today, ωc, allowing a large interaction rate |Γ| ~ H0. However, as has been known for a while, the BAO data break this degeneracy. Moreover, we exploit the CMB lensing potential likelihood, which probes the matter perturbations at redshift z ~ 2 and is very sensitive to the growth of structure, and hence one of the tools for discerning between the ΛCDM model and its alternatives. However, we find that in the non-phantom models (wde>-1), the constraints remain unchanged by the inclusion of the lensing data and consistent with zero interaction, -0.14 < Γ/H0 < 0.02 at 95% CL. On the contrary, in the phantom models (wde<-1), energy transfer from dark energy to dark matter is moderately favoured over the non-interacting model; 0-0.57 < Γ/H0 < -0.1 at 95% CL with CMB+BAO, while addition of the lensing data shifts this to -0.46 < Γ/H0 < -0.01.

  16. Broadband Acoustic Environment at a Tidal Energy Site in Puget Sound

    SciTech Connect

    Xu, Jinshan; Deng, Zhiqun; Martinez, Jayson J.; Carlson, Thomas J.; Myers, Joshua R.; Weiland, Mark A.

    2012-04-04

    Admiralty Inlet has been selected as a potential tidal energy site. It is located near shipping lanes, is a highly variable acoustic environment, and is frequented by the endangered southern resident killer whale (SRKW). Resolving environmental impacts is the first step to receiving approval to deploy tidal turbines. Several monitoring technologies are being considered to determine the presence of SRKW near the turbines. Broadband noise level measurements are critical for determining design and operational specifications of these technologies. Acoustic environment data at the proposed site was acquired at different depths using a cabled vertical line array from three different cruises during high tidal period in February, May, and June 2011. The ambient noise level decreases approximately 25 dB re 1 μPa per octave from frequency ranges of 1 kHz to 70 kHz, and increases approximately 20 dB re 1 μPa per octave for the frequency from 70 kHz to 200 kHz. The difference of noise pressure levels in different months varies from 10 to 30 dB re 1 μPa for the frequency range below 70 kHz. Commercial shipping and ferry vessel traffic were found to be the most significant contributors to sound pressure levels for the frequency range from 100 Hz to 70 kHz, and the variation could be as high as 30 dB re 1 μPa. These noise level measurements provide the basic information for designing and evaluating both active and passive monitoring systems proposed for deploying and operating for tidal power generation alert system.

  17. Study of Sequential Dexter Energy Transfer in High Efficient Phosphorescent White Organic Light-Emitting Diodes with Single Emissive Layer

    NASA Astrophysics Data System (ADS)

    Kim, Jin Wook; You, Seung Il; Kim, Nam Ho; Yoon, Ju-An; Cheah, Kok Wai; Zhu, Fu Rong; Kim, Woo Young

    2014-11-01

    In this study, we report our effort to realize high performance single emissive layer three color white phosphorescent organic light emitting diodes (PHOLEDs) through sequential Dexter energy transfer of blue, green and red dopants. The PHOLEDs had a structure of; ITO(1500 Å)/NPB(700 Å)/mCP:Firpic-x%:Ir(ppy)3-0.5%:Ir(piq)3-y%(300 Å)/TPBi(300 Å)/Liq(20 Å)/Al(1200 Å). The dopant concentrations of FIrpic, Ir(ppy)3 and Ir(piq)3 were adjusted and optimized to facilitate the preferred energy transfer processes attaining both the best luminous efficiency and CIE color coordinates. The presence of a deep trapping center for charge carriers in the emissive layer was confirmed by the observed red shift in electroluminescent spectra. White PHOLEDs, with phosphorescent dopant concentrations of FIrpic-8.0%:Ir(ppy)3-0.5%:Ir(piq)3-0.5% in the mCP host of the single emissive layer, had a maximum luminescence of 37,810 cd/m2 at 11 V and a luminous efficiency of 48.10 cd/A at 5 V with CIE color coordinates of (0.35, 0.41).

  18. 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.

  19. Work function, field emitted electron energy spectrum and surface composition of silicon covered molybdenum

    NASA Astrophysics Data System (ADS)

    Osamu Nishikawa; Haruhiko Koyama; Masahiko Tomitori

    1991-04-01

    The variation of work functions and electronic structures of Mo surfaces with Si coverages was studied using the atom-probe with a field emission electron spectrometer (AP/FEES). The field emission microscope images of a Si/Mo surface indicate that the deposited Si atoms form micro-clusters, the work function of which is found to be more than 10% larger than the Mo substrate. The FEES spectrum of the clusters implies that the Si/Mo surface is semiconductive even if the Si coverage is reduced to a fraction of a monolayer. The work functions of the Mo silicides formed by heating the Si/Mo tips are about 10% smaller than that of a clean Mo surface and the FEES analysis indicates that the silicide surface is metallic. At the Si-Mo and silicide-Mo interfaces, energy spectra, work functions and compositions vary abruptly in the range of one to a few atomic layers.

  20. Acoustic Monitoring of Beluga Whale Interactions with Cook Inlet Tidal Energy Project

    SciTech Connect

    Worthington, Monty

    2014-02-05

    Cook Inlet, Alaska is home to some of the greatest tidal energy resources in the U.S., as well as an endangered population of beluga whales (Delphinapterus leucas). Successfully permitting and operating a tidal power project in Cook Inlet requires a biological assessment of the potential and realized effects of the physical presence and sound footprint of tidal turbines on the distribution, relative abundance, and behavior of Cook Inlet beluga whales. ORPC Alaska, working with the Project Team—LGL Alaska Research Associates, University of Alaska Anchorage, TerraSond, and Greeneridge Science—undertook the following U.S. Department of Energy (DOE) study to characterize beluga whales in Cook Inlet – Acoustic Monitoring of Beluga Whale Interactions with the Cook Inlet Tidal Energy Project (Project). ORPC Alaska, LLC, is a wholly-owned subsidiary of Ocean Renewable Power Company, LLC, (collectively, ORPC). ORPC is a global leader in the development of hydrokinetic power systems and eco-conscious projects that harness the power of ocean and river currents to create clean, predictable renewable energy. ORPC is developing a tidal energy demonstration project in Cook Inlet at East Foreland where ORPC has a Federal Energy Regulatory Commission (FERC) preliminary permit (P-13821). The Project collected baseline data to characterize pre-deployment patterns of marine mammal distribution, relative abundance, and behavior in ORPC’s proposed deployment area at East Foreland. ORPC also completed work near Fire Island where ORPC held a FERC preliminary permit (P-12679) until March 6, 2013. Passive hydroacoustic devices (previously utilized with bowhead whales in the Beaufort Sea) were adapted for study of beluga whales to determine the relative abundance of beluga whale vocalizations within the proposed deployment areas. Hydroacoustic data collected during the Project were used to characterize the ambient acoustic environment of the project site pre-deployment to inform the

  1. Search for acoustic signals from ultrahigh energy neutrinos in 1500 km{sup 3} of sea water

    SciTech Connect

    Kurahashi, Naoko; Gratta, Giorgio; Vandenbroucke, Justin

    2010-10-01

    An underwater acoustic sensor array spanning {approx}1500 km{sup 3} is used to search for cosmic-ray neutrinos of ultrahigh energies ( E{sub {nu}>}10{sup 18} eV). Approximately 328 million triggers accumulated over an integrated 130 days of data taking are analyzed. The sensitivity of the experiment is determined from a Monte Carlo simulation of the array using recorded noise conditions and expected waveforms. Two events are found to have properties compatible with showers in the energy range 10{sup 24} eVenergy neutrinos using the acoustic technique.

  2. Efficient Structure Resonance Energy Transfer from Microwaves to Confined Acoustic Vibrations in Viruses

    PubMed Central

    Yang, Szu-Chi; Lin, Huan-Chun; Liu, Tzu-Ming; Lu, Jen-Tang; Hung, Wan-Ting; Huang, Yu-Ru; Tsai, Yi-Chun; Kao, Chuan-Liang; Chen, Shih-Yuan; Sun, Chi-Kuang

    2015-01-01

    Virus is known to resonate in the confined-acoustic dipolar mode with microwave of the same frequency. However this effect was not considered in previous virus-microwave interaction studies and microwave-based virus epidemic prevention. Here we show that this structure-resonant energy transfer effect from microwaves to virus can be efficient enough so that airborne virus was inactivated with reasonable microwave power density safe for the open public. We demonstrate this effect by measuring the residual viral infectivity of influenza A virus after illuminating microwaves with different frequencies and powers. We also established a theoretical model to estimate the microwaves power threshold for virus inactivation and good agreement with experiments was obtained. Such structure-resonant energy transfer induced inactivation is mainly through physically fracturing the virus structure, which was confirmed by real-time reverse transcription polymerase chain reaction. These results provide a pathway toward establishing a new epidemic prevention strategy in open public for airborne virus. PMID:26647655

  3. High-Efficiency Photovoltaic Energy Conversion using Surface Acoustic Waves in Piezoelectric Semiconductors

    NASA Astrophysics Data System (ADS)

    Yakovenko, Victor

    2010-03-01

    We propose a radically new design for photovoltaic energy conversion using surface acoustic waves (SAWs) in piezoelectric semiconductors. The periodically modulated electric field from SAW spatially separates photogenerated electrons and holes to the maxima and minima of SAW, thus preventing their recombination. The segregated electrons and holes are transported by the moving SAW to the collecting electrodes of two types, which produce dc electric output. Recent experiments [1] using SAWs in GaAs have demonstrated the photon to current conversion efficiency of 85%. These experiments were designed for photon counting, but we propose to adapt these techniques for highly efficient photovoltaic energy conversion. The advantages are that the electron-hole segregation takes place in the whole volume where SAW is present, and the electrons and holes are transported in the organized, collective manner at high speed, as opposed to random diffusion in conventional devices.[4pt] [1] S. J. Jiao, P. D. Batista, K. Biermann, R. Hey, and P. V. Santos, J. Appl. Phys. 106, 053708 (2009).

  4. Efficient Structure Resonance Energy Transfer from Microwaves to Confined Acoustic Vibrations in Viruses.

    PubMed

    Yang, Szu-Chi; Lin, Huan-Chun; Liu, Tzu-Ming; Lu, Jen-Tang; Hung, Wan-Ting; Huang, Yu-Ru; Tsai, Yi-Chun; Kao, Chuan-Liang; Chen, Shih-Yuan; Sun, Chi-Kuang

    2015-01-01

    Virus is known to resonate in the confined-acoustic dipolar mode with microwave of the same frequency. However this effect was not considered in previous virus-microwave interaction studies and microwave-based virus epidemic prevention. Here we show that this structure-resonant energy transfer effect from microwaves to virus can be efficient enough so that airborne virus was inactivated with reasonable microwave power density safe for the open public. We demonstrate this effect by measuring the residual viral infectivity of influenza A virus after illuminating microwaves with different frequencies and powers. We also established a theoretical model to estimate the microwaves power threshold for virus inactivation and good agreement with experiments was obtained. Such structure-resonant energy transfer induced inactivation is mainly through physically fracturing the virus structure, which was confirmed by real-time reverse transcription polymerase chain reaction. These results provide a pathway toward establishing a new epidemic prevention strategy in open public for airborne virus. PMID:26647655

  5. 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.

  6. Novel red-emitting Ba2Tb(BO3)2Cl:Eu phosphor with efficient energy transfer for potential application in white light-emitting diodes.

    PubMed

    Xia, Zhiguo; Zhuang, Jiaqing; Liao, Libing

    2012-07-01

    A novel red-emitting Ba(2)Tb(BO(3))(2)Cl:Eu phosphor possessing a broad excitation band in the near-ultraviolet (n-UV) region was synthesized by the solid-state reaction. Versatile Ba(2)Tb(BO(3))(2)Cl compound has a rigid open framework, which can offer two types of sites for various valence's cations to occupy, and the coexistence of Eu(2+)/Eu(3+) and the red-emitting luminescence from Eu(3+) with the aid of efficient energy transfer of Eu(2+)-Eu(3+)(Tb(3+)) and Tb(3+)-Eu(3+) have been investigated. Ba(2)Tb(BO(3))(2)Cl emits green emission with the main peak around 543 nm, which originates from (5)D(4) → (7)F(5) transition of Tb(3+). Ba(2)Tb(BO(3))(2)Cl:Eu shows bright red emission from Eu(3+) with peaks around 594, 612, and 624 nm under n-UV excitation (350-420 nm). The existence of Eu(2+) can be testified by the broad-band excitation spectrum, UV-vis reflectance spectrum, X-ray photoelectron spectrum, and Eu L(3)-edge X-ray absorption spectrum. Decay time and time-resolved luminescence measurements indicated that the interesting luminescence behavior should be ascribed to efficient energy transfer of Eu(2+)-Eu(3+)(Tb(3+)) and Tb(3+)-Eu(3+) in Ba(2)Tb(BO(3))(2)Cl:Eu phosphors. PMID:22686374

  7. NEW OPTICAL/ULTRAVIOLET COUNTERPARTS AND THE SPECTRAL ENERGY DISTRIBUTIONS OF NEARBY, THERMALLY EMITTING, ISOLATED NEUTRON STARS

    SciTech Connect

    Kaplan, D. L.; Kamble, A.; Van Kerkwijk, M. H.; Ho, W. C. G. E-mail: kamble@uwm.edu E-mail: wynnho@slac.stanford.edu

    2011-08-01

    We present Hubble Space Telescope optical and ultraviolet photometry for five nearby, thermally emitting neutron stars. With these measurements, all seven such objects have confirmed optical and ultraviolet counterparts. Combining our data with archival space-based photometry, we present spectral energy distributions for all sources and measure the 'optical excess': the factor by which the measured photometry exceeds that extrapolated from X-ray spectra. We find that the majority have optical and ultraviolet fluxes that are inconsistent with that expected from thermal (Rayleigh-Jeans) emission, exhibiting more flux at longer wavelengths. We also find that most objects have optical excesses between 5 and 12, but that one object (RX J2143.0+0654) exceeds the X-ray extrapolation by a factor of more than 50 at 5000 A, and that this is robust to uncertainties in the X-ray spectra and absorption. We consider explanations for this ranging from atmospheric effects, magnetospheric emission, and resonant scattering, but find that none is satisfactory.

  8. Luminescence and energy transfer of white emitting phosphor YAl3(BO3)4:Ce3+, Dy3+

    NASA Astrophysics Data System (ADS)

    Zhou, Fen; Wang, Di; Cao, He-ying; Li, Jing; Song, Hui-ling; Li, Pan-lai; Wang, Zhi-jun; Zhang, Kun; Pang, Li-bin

    2015-03-01

    A white emitting phosphor of YAl3(BO3)4:Ce3+, Dy3+ is synthesized by a solid state reaction, and its luminescent properties are investigated. Its phase formation is carried out with X-ray powder diffraction analysis, and there is no crystalline phase other than YAl3(BO3)4. YAl3(BO3)4:Ce3+ can produce 422 nm blue emission under 367 nm excitation. The emission spectrum of YAl3(BO3)4:Dy3+ shows several emission peaks under 350 nm excitation, and the peaks locate at 485 nm, 575 nm and 668 nm, respectively. Emission intensities of Ce3+ and Dy3+ in YAl3(BO3)4 are influenced by their concentrations, and the concentration quenching effect is observed. Energy transfer from Ce3+ to Dy3+ in YAl3(BO3)4 is validated and proved to be a resonant type via a quadrupole-quadrupole interaction, and the emission color can be tuned from blue to white by tuning the ratio of Ce3+/Dy3+. Moreover, the critical distance ( R c) of Ce3+ to Dy3+ in YAl3(BO3)4 is calculated to be 1.904 nm.

  9. Energy transfer from Sm3+ to Eu3+ in red-emitting phosphor LaMgAl11O19:Sm3+, Eu3+ for solar cells and near-ultraviolet white light-emitting diodes.

    PubMed

    Min, Xin; Huang, Zhaohui; Fang, Minghao; Liu, Yan-Gai; Tang, Chao; Wu, Xiaowen

    2014-06-16

    The red-emitting phosphor LaMgAl11O19:Sm(3+), Eu(3+) was prepared by solid-state reaction at 1600 °C for 4 h. The phase formation, luminescence properties, and energy transfer from Sm(3+) to Eu(3+) were studied. With the addition of 5 mol % Sm(3+) as the sensitizer, the excitation wavelength of LaMgAl11O19:Eu(3+) phosphor was extended from 464 to 403 nm, and the emission intensity under the excitation at 403 nm was also enhanced. The host material LaMgAl11O19 could contain the high doping content of Eu(3+) (20 mol %) without concentration quenching. This energy transfer from Sm(3+) to Eu(3+) was confirmed by the decay times of energy donor Sm(3+). The mechanism of energy transfer (Sm(3+) → Eu(3+)) was proved to be quadrupole-quadrupole interaction. Under the 403 nm excitation at 150 °C, the emission intensities of the characteristic peaks of Sm(3+) and Eu(3+) in LaMgAl11O19:0.05Sm(3+), 0.2Eu(3+) phosphor were decreased to 65% and 56% of the initial intensities at room temperature, and the relatively high activation energy proved that this phosphor had a good thermal stability. The CIE coordinate was calculated to be (x = 0.601, y = 0.390). The LaMgAl11O19:0.05Sm(3+), 0.2Eu(3+) phosphor is a candidate for copper phthalocyanine-based solar cells and white light-emitting diodes. PMID:24884208

  10. Model-independent Evidence for Dark Energy Evolution from Baryon Acoustic Oscillations

    NASA Astrophysics Data System (ADS)

    Sahni, V.; Shafieloo, A.; Starobinsky, A. A.

    2014-10-01

    Baryon acoustic oscillations (BAOs) allow us to determine the expansion history of the universe, thereby shedding light on the nature of dark energy. Recent observations of BAOs in the Sloan Digital Sky Survey (SDSS) DR9 and DR11 have provided us with statistically independent measurements of H(z) at redshifts of 0.57 and 2.34, respectively. We show that these measurements can be used to test the cosmological constant hypothesis in a model-independent manner by means of an improved version of the Om diagnostic. Our results indicate that the SDSS DR11 measurement of H(z) = 222 ± 7 km s-1 Mpc-1 at z = 2.34, when taken in tandem with measurements of H(z) at lower redshifts, imply considerable tension with the standard ΛCDM model. Our estimation of the new diagnostic Omh 2 from SDSS DR9 and DR11 data, namely, Omh 2 ≈ 0.122 ± 0.01, which is equivalent to Ω0m h 2 for the spatially flat ΛCDM model, is in tension with the value Ω0m h 2 = 0.1426 ± 0.0025 determined for ΛCDM from Planck+WP. This tension is alleviated in models in which the cosmological constant was dynamically screened (compensated) in the past. Such evolving dark energy models display a pole in the effective equation of state of dark energy at high redshifts, which emerges as a smoking gun test for these theories.

  11. MODEL-INDEPENDENT EVIDENCE FOR DARK ENERGY EVOLUTION FROM BARYON ACOUSTIC OSCILLATIONS

    SciTech Connect

    Sahni, V.; Shafieloo, A.; Starobinsky, A. A. E-mail: arman@apctp.org

    2014-10-01

    Baryon acoustic oscillations (BAOs) allow us to determine the expansion history of the universe, thereby shedding light on the nature of dark energy. Recent observations of BAOs in the Sloan Digital Sky Survey (SDSS) DR9 and DR11 have provided us with statistically independent measurements of H(z) at redshifts of 0.57 and 2.34, respectively. We show that these measurements can be used to test the cosmological constant hypothesis in a model-independent manner by means of an improved version of the Om diagnostic. Our results indicate that the SDSS DR11 measurement of H(z) = 222 ± 7 km s{sup –1} Mpc{sup –1} at z = 2.34, when taken in tandem with measurements of H(z) at lower redshifts, imply considerable tension with the standard ΛCDM model. Our estimation of the new diagnostic Omh {sup 2} from SDSS DR9 and DR11 data, namely, Omh {sup 2} ≈ 0.122 ± 0.01, which is equivalent to Ω{sub 0m} h {sup 2} for the spatially flat ΛCDM model, is in tension with the value Ω{sub 0m} h {sup 2} = 0.1426 ± 0.0025 determined for ΛCDM from Planck+WP. This tension is alleviated in models in which the cosmological constant was dynamically screened (compensated) in the past. Such evolving dark energy models display a pole in the effective equation of state of dark energy at high redshifts, which emerges as a smoking gun test for these theories.

  12. Production and Validation of Acoustic Field to Enhance Trapping Efficiency of Microbubbles by Using a Matrix Array Transducer

    NASA Astrophysics Data System (ADS)

    Hosaka, Naoto; Koda, Ren; Onogi, Shinya; Mochizuki, Takashi; Masuda, Kohji

    2013-07-01

    We have developed a new matrix array transducer for controlling the behavior of microbubbles, which is different from that for high-intensity focused ultrasound (HIFU) therapy, in order to emit continuous wave by designing an acoustic field including multiple focal points. In the experiment using a thin-channel model, a wider acoustic field has an advantage for trapping microbubbles. In the experiment using a straight-path model, we have confirmed that a higher concentration of acoustic energy does not result in more aggregates. The dispersion of acoustic energy is important because the trapping performance is affected by the relationship between the shape of the acoustic field and the concentration of the suspension.

  13. First cosmological constraints on dark energy from the radial baryon acoustic scale.

    PubMed

    Gaztañaga, Enrique; Miquel, Ramon; Sánchez, Eusebio

    2009-08-28

    We present cosmological constraints arising from the first measurement of the radial (line-of-sight) baryon acoustic oscillations (BAO) scale in the large scale structure traced by the galaxy distribution. Here we use these radial BAO measurements at z = 0.24 and z = 0.43 to derive new constraints on dark energy and its equation of state for a flat universe, without any other assumptions on the cosmological model: w = -1.14 + or - 0.39 (assumed constant), Omega(m) = 0.24(-0.05);(+0.06). If we drop the assumption of flatness and include previous cosmic microwave background and supernova data, we find w = -0.974 + or - 0.058, Omega(m) = 0.271 + or - 0.015, and Omega(k) = -0.002 + or - 0.006, in good agreement with a flat cold dark matter cosmology with a cosmological constant. To our knowledge, these are the most stringent constraints on these parameters to date under our stated assumptions. PMID:19792779

  14. Monitoring acoustic emission (AE) energy in slurry impingement using a new model for particle impact

    NASA Astrophysics Data System (ADS)

    Droubi, M. G.; Reuben, R. L.; White, G.

    2015-10-01

    A series of systematic impact tests have been carried out to investigate the influence of particle size, free stream velocity, particle impact angle, and nominal particle concentration on the amount of energy dissipated in a carbon steel target using a slurry impingement erosion test rig, as indicated by the acoustic emission (AE) recorded by a sensor mounted on the back of the target. Silica sand particles of mean particle size 152.5, 231, and 362.5 μm were used for impingement on the target at angles varying between 30° and 90° while the free stream velocity was changed between 4.2 and 12.7 m/s. In previous work by the authors, it was demonstrated that the AE time series associated with particle-laden air striking a carbon steel target could be described as the cumulation of individual particle arrival events each drawn from a statistical distribution model. The high arrival rate involved in a slurry jet poses challenges in resolving individual particle impact signatures in the AE record, and so the model has been extended in this paper to account for different particle carrier-fluids and to situations where arrivals cannot necessarily be resolved.

  15. Throughput and Energy Efficiency of a Cooperative Hybrid ARQ Protocol for Underwater Acoustic Sensor Networks

    PubMed Central

    Ghosh, Arindam; Lee, Jae-Won; Cho, Ho-Shin

    2013-01-01

    Due to its efficiency, reliability and better channel and resource utilization, cooperative transmission technologies have been attractive options in underwater as well as terrestrial sensor networks. Their performance can be further improved if merged with forward error correction (FEC) techniques. In this paper, we propose and analyze a retransmission protocol named Cooperative-Hybrid Automatic Repeat reQuest (C-HARQ) for underwater acoustic sensor networks, which exploits both the reliability of cooperative ARQ (CARQ) and the efficiency of incremental redundancy-hybrid ARQ (IR-HARQ) using rate-compatible punctured convolution (RCPC) codes. Extensive Monte Carlo simulations are performed to investigate the performance of the protocol, in terms of both throughput and energy efficiency. The results clearly reveal the enhancement in performance achieved by the C-HARQ protocol, which outperforms both CARQ and conventional stop and wait ARQ (S&W ARQ). Further, using computer simulations, optimum values of various network parameters are estimated so as to extract the best performance out of the C-HARQ protocol. PMID:24217359

  16. Throughput and energy efficiency of a cooperative hybrid ARQ protocol for underwater acoustic sensor networks.

    PubMed

    Ghosh, Arindam; Lee, Jae-Won; Cho, Ho-Shin

    2013-01-01

    Due to its efficiency, reliability and better channel and resource utilization, cooperative transmission technologies have been attractive options in underwater as well as terrestrial sensor networks. Their performance can be further improved if merged with forward error correction (FEC) techniques. In this paper, we propose and analyze a retransmission protocol named Cooperative-Hybrid Automatic Repeat reQuest (C-HARQ) for underwater acoustic sensor networks, which exploits both the reliability of cooperative ARQ (CARQ) and the efficiency of incremental redundancy-hybrid ARQ (IR-HARQ) using rate-compatible punctured convolution (RCPC) codes. Extensive Monte Carlo simulations are performed to investigate the performance of the protocol, in terms of both throughput and energy efficiency. The results clearly reveal the enhancement in performance achieved by the C-HARQ protocol, which outperforms both CARQ and conventional stop and wait ARQ (S&W ARQ). Further, using computer simulations, optimum values of various network parameters are estimated so as to extract the best performance out of the C-HARQ protocol. PMID:24217359

  17. Health sensor for human body by using infrared, acoustic energy and magnetic signature

    NASA Astrophysics Data System (ADS)

    Wu, Jerry

    2013-05-01

    There is a general chain of events that applies to infections. Human body infection could causes by many different types of bacteria and virus in different areas or organ systems. In general, doctor can't find out the right solution/treatment for infections unless some certain types of bacteria or virus are detected. These detecting processes, usually, take few days to one week to accomplish. However, some infections of the body may not be able to detect at first round and the patient may lose the timing to receive the proper treatment. In this works, we base on Chi's theory which is an invisible circulation system existed inside the body and propose a novel health sensor which summarizes human's infrared, acoustic energy and magnetic signature and find out, in minutes, the most possible area or organ system that cause the infection just like what Chi-Kung master can accomplish. Therefore, the detection process by doctor will be shortened and it raises the possibility to give the proper treatment to the patient in the earliest timing.

  18. Kinetic modeling of ultrasound-assisted extraction of phenolic compounds from grape marc: influence of acoustic energy density and temperature.

    PubMed

    Tao, Yang; Zhang, Zhihang; Sun, Da-Wen

    2014-07-01

    The effects of acoustic energy density (6.8-47.4 W/L) and temperature (20-50 °C) on the extraction yields of total phenolics and tartaric esters during ultrasound-assisted extraction from grape marc were investigated in this study. The ultrasound treatment was performed in a 25-kHz ultrasound bath system and the 50% aqueous ethanol was used as the solvent. The initial extraction rate and final extraction yield increased with the increase of acoustic energy density and temperature. The two site kinetic model was used to simulate the kinetics of extraction process and the diffusion model based on the Fick's second law was employed to determine the effective diffusion coefficient of phenolics in grape marc. Both models gave satisfactory quality of data fit. The diffusion process was divided into one fast stage and one slow stage and the diffusion coefficients in both stages were calculated. Within the current experimental range, the diffusion coefficients of total phenolics and tartaric esters for both diffusion stages increased with acoustic energy density. Meanwhile, the rise of temperature also resulted in the increase of diffusion coefficients of phenolics except the diffusion coefficient of total phenolics in the fast stage, the value of which being the highest at 40 °C. Moreover, an empirical equation was suggested to correlate the effective diffusion coefficient of phenolics in grape marc with acoustic energy density and temperature. In addition, the performance comparison of ultrasound-assisted extraction and convention methods demonstrates that ultrasound is an effective and promising technology to extract bioactive substances from grape marc. PMID:24613646

  19. Method and system for generating a beam of acoustic energy from a borehole, and applications thereof

    DOEpatents

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

    2012-02-14

    A compact array of transducers is employed as a downhole instrument for acoustic investigation of the surrounding rock formation. The array is operable to generate simultaneously a first acoustic beam signal at a first frequency and a second acoustic beam signal at a second frequency different than the first frequency. These two signals can be oriented through an azimuthal rotation of the array and an inclination rotation using control of the relative phases of the signals from the transmitter elements or electromechanical linkage. Due to the non-linearity of the formation, the first and the second acoustic beam signal mix into the rock formation where they combine into a collimated third signal that propagates in the formation along the same direction than the first and second signals and has a frequency equal to the difference of the first and the second acoustic signals. The third signal is received either within the same borehole, after reflection, or another borehole, after transmission, and analyzed to determine information about rock formation. Recording of the third signal generated along several azimuthal and inclination directions also provides 3D images of the formation, information about 3D distribution of rock formation and fluid properties and an indication of the dynamic acoustic non-linearity of the formation.

  20. Using light emitted clusters as a probe of the symmetry energy in the nuclear equation of state

    NASA Astrophysics Data System (ADS)

    Youngs, Michael David

    The symmetry energy, and more specifically its density dependence, has been studied for quite some time from both a theoretical and experimental approach. In order to sufficiently constrain the symmetry energy, we need to experimentally measure observables sensitive to the symmetry energy within a reasonable uncertainty and compare those results to those of simulations of the same nuclear reactions. This dissertation aims to achieve both experimental measurements and compare them to the results of studies using the pBUU transport code. These studies using pBUU aim to find the sensitivity of different observables to different transport variables as well as the symmetry energy itself. Some of the predominant variables that have been investigated in this dissertation are the in-medium cross section between nucleons as well as the effect of cluster production. The specific observables upon which we report are the center of mass spectra of protons, neutrons, deuterons, tritons and finally 3He. In addition we investigate the n/p and t/3He single and double ratios which have been suggested as being sensitive to the symmetry energy. As an added check we also study the coalescence invariant n/p spectra and ratios. We also include a study of spectra for all charged particles up through mass A=4 emitted from reactions of 112Sn+112Sn and 124Sn+124Sn at both 50 and 120 MeV/A. The experiment to measure these reactions used the Large Area Silicon Strip Array to detect the charged particles and the MSU Miniball to detect charge particle multiplicity in order to select central collisions. Neutrons were also measured in this experiment using the Large Area Neutron Array along with two thin scintillators used as a start timer for the neutron walls and a charge particle veto to discern contamination in the neutron walls. The neutron analyses are not extensively reported in this dissertation as they were the focus of the dissertation of Daniel Coupland [1]. Finally, another

  1. Can seismic (destructive) energy be stored after conversion into useful electrical or acoustic energy?

    NASA Astrophysics Data System (ADS)

    Verma, Umesh P.; Sinha, Madhurendra N.

    2014-06-01

    Since the dawn of precursory revolution in the seismology and electromagnetic radiation platform., F.T. Freund (2010) et.al, have used piezoelectric effect on the crustal geo-materials and emanation of seismic pre signals frequently. Their effect in form of ULF and VHF are commonly detected (by Greece and American seismologists)in the upper ionosphere from surface of globe. TEC, OLR. MMC are the consequent instrumentation in acquiring data to these pre-earthquake signals. Our attempt is to detect the signals prior to earthquake due to impending stress in the area and store the spreading destructive energy to electrical voltage applying the mathematics of piezoelectric equations and algebra. Energy released during seismic eruption is in the range of 10 13 to 1018 Joule for each event of 6 to 8 Mw. Spread and propagation of energy follows the Maxwell theory of wave equation and fundamental law of electricity and electromagnetism. Stress accumulated within the crustal block is triggered into bringing about geophysical and geochemical changes within the reservoir rocks interacting stress. Study made by pioneers in the seismic precursory development states generation of charge and coronal discharge prior seismicity within the rocks under stress. This is consequence to admixing of positive charge developed at unstressed volume and negative at stressed sub volume of rocks1 [F.T.Freidemann2010]. Ionosphere proturbance in form of ULF, ELF, ELS and EQL, EQS are the projected consequence of electromagnetic wave propagation 2 [10,11,15 ] Harnessing of electrical components from the energy propagated due to stress inducing EM waves is the aim of paper. Electrical discharge prior to seismicity within geo-materials is established phenomena which can be calibrated with the piezoelectric sensors application implanted for detection and harnessing the signals. These prior signals induced in form of electromagnetic response are felicitated into being converted into electrical energy

  2. An experimental study of vibration based energy harvesting in dynamically tailored structures with embedded acoustic black holes

    NASA Astrophysics Data System (ADS)

    Zhao, Liuxian; Conlon, Stephen C.; Semperlotti, Fabio

    2015-06-01

    In this paper, we present an experimental investigation on the energy harvesting performance of dynamically tailored structures based on the concept of embedded acoustic black holes (ABHs). Embedded ABHs allow tailoring the wave propagation characteristics of the host structure creating structural areas with extreme levels of energy density. Experiments are conducted on a tapered plate-like aluminum structure with multiple embedded ABH features. The dynamic response of the structure is tested via laser vibrometry in order to confirm the vibration localization and the passive wavelength sweep characteristic of ABH embedded tapers. Vibrational energy is extracted from the host structure and converted into electrical energy by using ceramic piezoelectric discs bonded on the ABHs and shunted on an external electric circuit. The energy harvesting performance is investigated both under steady state and transient excitation. The experimental results confirm that the dynamic tailoring produces a drastic increase in the harvested energy independently from the nature of the excitation input.

  3. Simultaneous backward data transmission and power harvesting in an ultrasonic transcutaneous energy transfer link employing acoustically dependent electric impedance modulation.

    PubMed

    Ozeri, Shaul; Shmilovitz, Doron

    2014-09-01

    The advancement and miniaturization of body implanted medical devices pose several challenges to Ultrasonic Transcutaneous Energy Transfer (UTET), such as the need to reduce the size of the piezoelectric resonator, and the need to maximize the UTET link power-transfer efficiency. Accordingly, the same piezoelectric resonator that is used for energy harvesting at the body implant, may also be used for ultrasonic backward data transfer, for instance, through impedance modulation. This paper presents physical considerations and design guidelines of the body implanted transducer of a UTET link with impedance modulation for a backward data transfer. The acoustic matching design procedure was based on the 2×2 transfer matrix chain analysis, in addition to the Krimholtz Leedom and Matthaei KLM transmission line model. The UTET power transfer was carried out at a frequency of 765 kHz, continuous wave (CW) mode. The backward data transfer was attained by inserting a 9% load resistance variation around its matched value (550 Ohm), resulting in a 12% increase in the acoustic reflection coefficient. A backward data transmission rate of 1200 bits/s was experimentally demonstrated using amplitude shift keying, simultaneously with an acoustic power transfer of 20 mW to the implant. PMID:24861424

  4. An Energy Signature Scheme for Steam Trap Assessment and Flow Rate Estimation Using Pipe-Induced Acoustic Measurements

    SciTech Connect

    Olama, Mohammed M; Allgood, Glenn O; Kuruganti, Phani Teja; Lake, Joe E

    2012-01-01

    The US Congress has passed legislation dictating that all government agencies establish a plan and process for improving energy efficiencies at their sites. In response to this legislation, Oak Ridge National Laboratory (ORNL) has recently conducted a pilot study to explore the deployment of a wireless sensor system for a real-time measurement-based energy efficiency optimization framework within the steam distribution system within the ORNL campus. We make assessments on the real-time status of the distribution system by observing the state measurements of acoustic sensors mounted on the steam pipes/traps/valves. In this paper, we describe a spectral-based energy signature scheme that interprets acoustic vibration sensor data to estimate steam flow rates and assess steam traps health status. Experimental results show that the energy signature scheme has the potential to identify different steam trap health status and it has sufficient sensitivity to estimate steam flow rate. Moreover, results indicate a nearly quadratic relationship over the test region between the overall energy signature factor and flow rate in the pipe. The analysis based on estimated steam flow and steam trap status helps generate alerts that enable operators and maintenance personnel to take remedial action. The goal is to achieve significant energy-saving in steam lines by monitoring and acting on leaking steam pipes/traps/valves.

  5. An energy signature scheme for steam trap assessment and flow rate estimation using pipe-induced acoustic measurements

    NASA Astrophysics Data System (ADS)

    Olama, Mohammed M.; Allgood, Glenn O.; Kuruganti, Teja P.; Lake, Joe E.

    2012-06-01

    The US Congress has passed legislation dictating that all government agencies establish a plan and process for improving energy efficiencies at their sites. In response to this legislation, Oak Ridge National Laboratory (ORNL) has recently conducted a pilot study to explore the deployment of a wireless sensor system for a real-time measurement-based energy efficiency optimization framework within the steam distribution system within the ORNL campus. We make assessments on the real-time status of the distribution system by observing the state measurements of acoustic sensors mounted on the steam pipes/traps/valves. In this paper, we describe a spectral-based energy signature scheme that interprets acoustic vibration sensor data to estimate steam flow rates and assess steam traps health status. Experimental results show that the energy signature scheme has the potential to identify different steam trap health status and it has sufficient sensitivity to estimate steam flow rate. Moreover, results indicate a nearly quadratic relationship over the test region between the overall energy signature factor and flow rate in the pipe. The analysis based on estimated steam flow and steam trap status helps generate alerts that enable operators and maintenance personnel to take remedial action. The goal is to achieve significant energy-saving in steam lines by monitoring and acting on leaking steam pipes/traps/valves.

  6. Single-phased white-light-emitting Ca₄(PO₄)₂O:Ce³⁺,Eu²⁺ phosphors based on energy transfer.

    PubMed

    Jia, Yonglei; Pang, Ran; Li, Haifeng; Sun, Wenzhi; Fu, Jipeng; Jiang, Lihong; Zhang, Su; Su, Qiang; Li, Chengyu; Liu, Ru-Shi

    2015-07-01

    A novel single-composition Ca4(PO4)2O:Ce(3+),Eu(2+) phosphor emitting white light was synthesized by conventional solid-state reaction for light-emitting diode applications. X-ray diffraction, photoluminescence spectra, and luminescence decay spectra were used to characterize the samples. Energy transfer from Ce(3+) to Eu(2+) ions was observed in the co-doped samples, and the transfer mechanism in the Ca4(PO4)2O:Ce(3+),Eu(2+) phosphors was dipole-dipole interaction. The emission hue of Ca4(PO4)2O:Ce(3+),Eu(2+) was found to vary from blue (0.165, 0.188) to white (0.332, 0.300) and eventually to orange (0.519, 0.366) by precisely controlling the ratio of Ce(3+) to Eu(2+). The combination of a 380 nm near-ultraviolet chip with a Ca4(PO4)2O:0.02Ce(3+),0.012Eu(2+) phosphor produced a diode emitting white light with ultra-wideband emission and a correlated color temperature of 4124 K. Overall, results indicated that the prepared samples may be potentially applied in white-light-emitting diodes. PMID:26017804

  7. Dose calculation for photon-emitting brachytherapy sources with average energy higher than 50 keV: Report of the AAPM and ESTRO

    SciTech Connect

    Perez-Calatayud, Jose; Ballester, Facundo; Das, Rupak K.; DeWerd, Larry A.; Ibbott, Geoffrey S.; Meigooni, Ali S.; Ouhib, Zoubir; Rivard, Mark J.; Sloboda, Ron S.; Williamson, Jeffrey F.

    2012-05-15

    Purpose: Recommendations of the American Association of Physicists in Medicine (AAPM) and the European Society for Radiotherapy and Oncology (ESTRO) on dose calculations for high-energy (average energy higher than 50 keV) photon-emitting brachytherapy sources are presented, including the physical characteristics of specific {sup 192}Ir, {sup 137}Cs, and {sup 60}Co source models. Methods: This report has been prepared by the High Energy Brachytherapy Source Dosimetry (HEBD) Working Group. This report includes considerations in the application of the TG-43U1 formalism to high-energy photon-emitting sources with particular attention to phantom size effects, interpolation accuracy dependence on dose calculation grid size, and dosimetry parameter dependence on source active length. Results: Consensus datasets for commercially available high-energy photon sources are provided, along with recommended methods for evaluating these datasets. Recommendations on dosimetry characterization methods, mainly using experimental procedures and Monte Carlo, are established and discussed. Also included are methodological recommendations on detector choice, detector energy response characterization and phantom materials, and measurement specification methodology. Uncertainty analyses are discussed and recommendations for high-energy sources without consensus datasets are given. Conclusions: Recommended consensus datasets for high-energy sources have been derived for sources that were commercially available as of January 2010. Data are presented according to the AAPM TG-43U1 formalism, with modified interpolation and extrapolation techniques of the AAPM TG-43U1S1 report for the 2D anisotropy function and radial dose function.

  8. Prediction of interior noise due to random acoustic or turbulent boundary layer excitation using statistical energy analysis

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.

    1990-01-01

    The feasibility of predicting interior noise due to random acoustic or turbulent boundary layer excitation was investigated in experiments in which a statistical energy analysis model (VAPEPS) was used to analyze measurements of the acceleration response and sound transmission of flat aluminum, lucite, and graphite/epoxy plates exposed to random acoustic or turbulent boundary layer excitation. The noise reduction of the plate, when backed by a shallow cavity and excited by a turbulent boundary layer, was predicted using a simplified theory based on the assumption of adiabatic compression of the fluid in the cavity. The predicted plate acceleration response was used as input in the noise reduction prediction. Reasonable agreement was found between the predictions and the measured noise reduction in the frequency range 315-1000 Hz.

  9. High-Q cross-plate phononic crystal resonator for enhanced acoustic wave localization and energy harvesting

    NASA Astrophysics Data System (ADS)

    Yang, Aichao; Li, Ping; Wen, Yumei; Yang, Chao; Wang, Decai; Zhang, Feng; Zhang, Jiajia

    2015-05-01

    A high-Q cross-plate phononic crystal resonator (Cr-PCR) coupled with an electromechanical Helmholtz resonator (EMHR) is proposed to improve acoustic wave localization and energy harvesting. Owing to the strongly directional wave-scattering effect of the cross-plate corners, strong confinement of acoustic waves emerges. Consequently, the proposed Cr-PCR structure exhibits ∼353.5 times higher Q value and ∼6.1 times greater maximum pressure amplification than the phononic crystal resonator (Cy-PCR) (consisting of cylindrical scatterers) of the same size. Furthermore, the harvester using the proposed Cr-PCR and the EMHR has ∼22 times greater maximum output-power volume density than the previous harvester using Cy-PCR and EMHR structures.

  10. Challenge of Using Passive Acoustic Monitoring in High-Energy Environments: UK Tidal Environments and Other Case Studies.

    PubMed

    Booth, Cormac G

    2016-01-01

    The use of passive acoustic monitoring (PAM) around marine developments is commonplace. A buffer-based PAM system (e.g., C-POD) is a cost-effective method for assessing cetacean acoustic presence. Devices have been deployed by Sea Mammal Research Unit (SMRU) Marine around the United Kingdom, allowing an examination of the performance of C-PODs with respect to background noise, tilt angle, and environmental factors. C-PODs were found to often only monitor for a few seconds of each minute, resulting in significant loss of monitoring time. Issues were likely driven by environmental and deployment factors. The practical limitations of buffer-based PAM systems in high-energy/noisy environments are indicated here. PMID:26610949

  11. Accelerator measurement of the energy spectra of neutrons emitted in the interaction of 3-GeV protons with several elements

    NASA Technical Reports Server (NTRS)

    Nalesnik, W. J.; Devlin, T. J.; Merker, M.; Shen, B. S. P.

    1972-01-01

    The application of time of flight techniques for determining the shapes of the energy spectra of neutrons between 20 and 400 MeV is discussed. The neutrons are emitted at 20, 34, and 90 degrees in the bombardment of targets by 3 GeV protons. The targets used are carbon, aluminum, cobalt, and platinum with cylindrical cross section. Targets being bombarded are located in the internal circulating beam of a particle accelerator.

  12. Inclusive spectra of protons emitted in interactions between /sup 3/He nuclei of energy 4. 9 GeV per nucleon and C, Cu, and Pb nuclei

    SciTech Connect

    Ad'yasevich, B.P.; Antonenko, V.G.; Vinogradov, A.A.; Grigor'yan, Y.I.; Ippolitov, M.S.; Karadzhev, K.V.; Lebedev, A.L.; Man'ko, V.I.; Nikolaev, S.A.; Polunin, Y.P.; and others

    1987-02-01

    We have measured inclusive spectra of protons emitted in interactions between /sup 3/He nuclei of energy 4.9 GeV per nucleon and C, Cu, and Pb nuclei. Data are presented on the invariant cross sections for proton yield in the range of emission angles from 20/sup 0/ to 150/sup 0/ for the momentum interval 350--850 MeV/c. The data obtained are analyzed.

  13. Highly Emitting Near-Infrared Lanthanide “Encapsulated Sandwich” Metallacrown Complexes with Excitation Shifted Toward Lower Energy

    PubMed Central

    2015-01-01

    Near-infrared (NIR) luminescent lanthanide complexes hold great promise for practical applications, as their optical properties have several complementary advantages over organic fluorophores and semiconductor nanoparticles. The fundamental challenge for lanthanide luminescence is their sensitization through suitable chromophores. The use of the metallacrown (MC) motif is an innovative strategy to arrange several organic sensitizers at a well-controlled distance from a lanthanide cation. Herein we report a series of lanthanide “encapsulated sandwich” MC complexes of the form Ln3+[12-MCZn(II),quinHA-4]2[24-MCZn(II),quinHA-8] (Ln3+[Zn(II)MCquinHA]) in which the MC framework is formed by the self-assembly of Zn2+ ions and tetradentate chromophoric ligands based on quinaldichydroxamic acid (quinHA). A first-generation of luminescent MCs was presented previously but was limited due to excitation wavelengths in the UV. We report here that through the design of the chromophore of the MC assembly, we have significantly shifted the absorption wavelength toward lower energy (450 nm). In addition to this near-visible inter- and/or intraligand charge transfer absorption, Ln3+[Zn(II)MCquinHA] exhibits remarkably high quantum yields, long luminescence lifetimes (CD3OD; Yb3+, QLnL = 2.88(2)%, τobs = 150.7(2) μs; Nd3+, QLnL = 1.35(1)%, τobs = 4.11(3) μs; Er3+, QLnL = 3.60(6)·10–2%, τobs = 11.40(3) μs), and excellent photostability. Quantum yields of Nd3+ and Er3+ MCs in the solid state and in deuterated solvents, upon excitation at low energy, are the highest values among NIR-emitting lanthanide complexes containing C–H bonds. The versatility of the MC strategy allows modifications in the excitation wavelength and absorptivity through the appropriate design of the ligand sensitizer, providing a highly efficient platform with tunable properties. PMID:24432702

  14. Bubbles trapped at the coupling surface of the treatment head significantly reduce acoustic energy delivered in shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Pishchalnikov, Yuri A.; McAteer, James A.; Pishchalnikova, Irina V.; Beard, Spencer; Williams, James C.; Bailey, Michael R.

    2006-05-01

    The coupling efficiency of a "dry head" electromagnetic lithotripter (Dornier Compact Delta) was studied in vitro. A fiber-optic probe hydrophone (FOPH-500) was positioned in a test tank filled with degassed water. The tank was coupled through a semi-transparent latex membrane to the water-filled cushion of the lithotripter head, so that bubbles (air pockets) trapped between the two coupling surfaces could be easily observed and photographed. When gel was applied to both the latex membrane and the water cushion, numerous bubbles (some several millimeters in diameter) could be seen at the coupling interface. Hydrophone measurements in the geometric focus of the lithotripter showed that the acoustic pressure could be two times lower when bubbles were present than when they were manually removed. In our in vitro design, trapped bubbles could be easily observed and therefore removed from the acoustic path. However, during patient treatment with a dry-head lithotripter one cannot see whether bubbles are trapped against the skin. This study provides a demonstration of the dramatic effect that trapped bubbles can have on the amount of acoustic energy actually delivered for treatment.

  15. Energy- and angular-distributions of F + ions emitted from a F-terminated Si(1 0 0) surface with slow highly charged ions

    NASA Astrophysics Data System (ADS)

    Okabayashi, N.; Komaki, K.; Yamazaki, Y.

    2005-07-01

    Time and two-dimensional position distributions of F+ ions emitted from a well-defined F/Si(1 0 0)-2 × 1 target were measured for impact of slow highly charged ions of 3.9 keV Ar5+. The time and position distributions were transformed into energy and angular distributions, which revealed that the peak emission energy was 2.0 ± 0.6 eV and the emission angle measured from the surface normal was 18 ± 4° in the (0 1 1) or (01 1 bar) plane.

  16. Evaluation of a UV-light emitting diodes unit for the removal of micropollutants in water for low energy advanced oxidation processes.

    PubMed

    Autin, Olivier; Romelot, Christophe; Rust, Lena; Hart, Julie; Jarvis, Peter; MacAdam, Jitka; Parsons, Simon A; Jefferson, Bruce

    2013-07-01

    There is growing interest in using light emitting diodes (LEDs) as alternative to traditional mercury lamps for the removal of micropollutants by advanced oxidation processes due to their low energy consumption and potential for high efficiency and long lifetime. This study investigates the penetration and coverage of the light emitted by LEDs in order to build an optimised LED collimated beam apparatus. From the experimental data, cost analysis was conducted in order to identify when LEDs will become economically viable. It was observed that if their development follows the predictions, LEDs should be a viable alternative to traditional lamps within 7yr for both UV/H2O2 and UV/TiO2 processes. However, parameters such as wall plug efficiency and input power need to improve for LEDs to become competitive. PMID:23668964

  17. 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.

  18. Asymptotic modal analysis and statistical energy analysis of an acoustic cavity

    NASA Technical Reports Server (NTRS)

    Kubota, Y.; Dionne, H. D.; Dowell, E. H.

    1988-01-01

    A basic asymptotic theory for structural wall/acoustic cavity interaction is presented, and the analysis is illustrated with examples of the acoustic cavity response to a prescribed wall motion. Although, when spatially averaged, the classical modal analysis (CMA) response approaches the asymptotic modal analysis (AMA) response more rapidly as the number of modes increases, it is shown that information about local response intensification is lost in the averaging process. A larger bandwidth at a given center frequency is found to contain more excited modes than a smaller bandwidth; however, the AMA is slightly more accurate in the smaller bandwidth. All AMA asymptotes were shown to be approached from below by a CMA with fixed bandwidth and increasing center frequency.

  19. System for generating a beam of acoustic energy from a borehole, and applications thereof

    DOEpatents

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian; Nihei, Kurt T.; Schmitt, Denis P.; Skelt, Christopher

    2012-07-31

    In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

  20. System for generating a beam of acoustic energy from a borehole, and applications thereof

    DOEpatents

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian; Nihei, Kurt T.; Schmitt, Denis P.; Skelt, Christopher

    2012-09-04

    In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

  1. Device and method for generating a beam of acoustic energy from a borehole, and applications thereof

    DOEpatents

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian; Nihei, Kurt; Schmitt, Denis P.; Skelt, Christopher

    2010-11-23

    In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

  2. 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.

  3. 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 ...

  4. A novel orange-yellow-emitting Ba3Lu(PO4)3:Eu2+,Mn2+ phosphor with energy transfer for UV-excited white LEDs.

    PubMed

    Guo, Ning; Huang, Yeju; Jia, Yongchao; Lv, Wenzhen; Zhao, Qi; Lü, Wei; Xia, Zhiguo; You, Hongpeng

    2013-01-28

    Eu(2+)-Mn(2+) codoped orange-yellow-emitting Ba(3)Lu(PO(4))(3) phosphors were synthesized by a solid-state reaction. The synthesis, structure refinement, and luminescence properties of the obtained phosphor were first investigated in detail. The crystal structure was refined with a split-atom model, where the oxygen atoms are distributed over two partially occupied sites. The refinement confirmed that BLuP:0.005Eu(2+),0.06Mn(2+) has a cubic unit cell with space group I43d (no. 220), cell parameters a = b = c = 10.4025 Å and Z = 4. The luminescent properties reveal that the developed phosphor can efficiently convert UV photons in a broad range from 230 to 430 nm into orange-yellow emission. On the basis of the luminescence spectra and fluorescence decay curves, we confirm that the energy transfer process from the Eu(2+) to Mn(2+) ions takes place in the codoped Ba(3)Lu(PO(4))(3):Eu(2+),Mn(2+) phosphor, and the energy transfer efficiency increases with an increase in the Mn(2+) content. The possible energy transfer mechanism was proposed in terms of the experimental results and analysis. In particular, our developed phosphor contains a larger amount of the red-emitting component, compared with the commercial YAG:Ce phosphor, possessing favorable properties for application in warm white LEDs with low correlated color temperature. PMID:23108262

  5. Detecting special nuclear materials in suspect containers using high-energy gamma rays emitted by fission products

    DOEpatents

    Norman, Eric B [Oakland, CA; Prussin, Stanley G [Kensington, CA

    2009-05-05

    A method and a system for detecting the presence of special nuclear materials in a suspect container. The system and its method include irradiating the suspect container with a beam of neutrons, so as to induce a thermal fission in a portion of the special nuclear materials, detecting the gamma rays that are emitted from the fission products formed by the thermal fission, to produce a detector signal, comparing the detector signal with a threshold value to form a comparison, and detecting the presence of the special nuclear materials using the comparison.

  6. Detecting special nuclear materials in suspect containers using high-energy gamma rays emitted by fission products

    DOEpatents

    Norman, Eric B.; Prussin, Stanley G.

    2009-01-06

    A method and a system for detecting the presence of special nuclear materials in a suspect container. The system and its method include irradiating the suspect container with a beam of neutrons, so as to induce a thermal fission in a portion of the special nuclear materials, detecting the gamma rays that are emitted from the fission products formed by the thermal fission, to produce a detector signal, comparing the detector signal with a threshold value to form a comparison, and detecting the presence of the special nuclear materials using the comparison.

  7. Detecting special nuclear materials in suspect containers using high-energy gamma rays emitted by fission products

    DOEpatents

    Norman, Eric B.; Prussin, Stanley G.

    2009-01-27

    A method and a system for detecting the presence of special nuclear materials in a suspect container. The system and its method include irradiating the suspect container with a beam of neutrons, so as to induce a thermal fission in a portion of the special nuclear materials, detecting the gamma rays that are emitted from the fission products formed by the thermal fission, to produce a detector signal, comparing the detector signal with a threshold value to form a comparison, and detecting the presence of the special nuclear materials using the comparison.

  8. Acoustic Seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

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

  9. 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.

  10. Thermoelectric Thin Film Devices for Energy Harvesting with the Heat Dissipated from High-Power Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Hwan; Kim, Woo-Jun; Oh, Tae-Sung

    2016-04-01

    We examined the power-generation characteristics of thin-film devices using the heat dissipated from high-power light-emitting diodes. The thin-film device was fabricated around an light-emitting diode (LED) chip by electrodepositing four pairs of the 10 μm-thick Bi2Te3 and Sb2Te3 films using either the high resistive Ti seed layer or the more conductive Ti/Cu/Au seed layer. The seed layer effect was more profound for the output power of the thin-film device than its output voltage. The open circuit voltages of 0.61 mV at ΔT for 4.1 K and 0.52 mV at ΔT for 4.9 K were obtained for the thin-film devices fabricated on the highly resistive Ti seed layer and the more conductive Ti/Cu/Au seed layer, respectively. Compared to 0.64 nW at ΔT for 4.1 K for the device processed on the more resistive Ti seed layer, a large maximum output power of 33.6 nW was obtained at ΔT of 4.9 K for the device built on the less resistive Ti/Cu/Au seed layer.

  11. Thermoelectric Thin Film Devices for Energy Harvesting with the Heat Dissipated from High-Power Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Hwan; Kim, Woo-Jun; Oh, Tae-Sung

    2016-07-01

    We examined the power-generation characteristics of thin-film devices using the heat dissipated from high-power light-emitting diodes. The thin-film device was fabricated around an light-emitting diode (LED) chip by electrodepositing four pairs of the 10 μm-thick Bi2Te3 and Sb2Te3 films using either the high resistive Ti seed layer or the more conductive Ti/Cu/Au seed layer. The seed layer effect was more profound for the output power of the thin-film device than its output voltage. The open circuit voltages of 0.61 mV at Δ T for 4.1 K and 0.52 mV at Δ T for 4.9 K were obtained for the thin-film devices fabricated on the highly resistive Ti seed layer and the more conductive Ti/Cu/Au seed layer, respectively. Compared to 0.64 nW at Δ T for 4.1 K for the device processed on the more resistive Ti seed layer, a large maximum output power of 33.6 nW was obtained at Δ T of 4.9 K for the device built on the less resistive Ti/Cu/Au seed layer.

  12. Asymmetric Cherenkov acoustic reverse in topological insulators

    NASA Astrophysics Data System (ADS)

    Smirnov, Sergey

    2014-09-01

    A general phenomenon of the Cherenkov radiation known in optics or acoustics of conventional materials is a formation of a forward cone of, respectively, photons or phonons emitted by a particle accelerated above the speed of light or sound in those materials. Here we suggest three-dimensional topological insulators as a unique platform to fundamentally explore and practically exploit the acoustic aspect of the Cherenkov effect. We demonstrate that by applying an in-plane magnetic field to a surface of a three-dimensional topological insulator one may suppress the forward Cherenkov sound up to zero at a critical magnetic field. Above the critical field the Cherenkov sound acquires pure backward nature with the polar distribution differing from the forward one generated below the critical field. Potential applications of this asymmetric Cherenkov reverse are in the design of low energy electronic devices such as acoustic ratchets or, in general, in low power design of electronic circuits with a magnetic field control of the direction and magnitude of the Cherenkov dissipation.

  13. Exciton energy recycling from ZnO defect levels: towards electrically driven hybrid quantum-dot white light-emitting-diodes

    NASA Astrophysics Data System (ADS)

    Zhao, Xin; Liu, Weizhen; Chen, Rui; Gao, Yuan; Zhu, Binbin; Demir, Hilmi Volkan; Wang, Shijie; Sun, Handong

    2016-03-01

    An electrically driven quantum-dot hybrid white light-emitting diode is fabricated via spin coating CdSe quantum dots onto a GaN/ZnO nanorod matrix. For the first time, quantum dots are excited by fluorescence resonance energy transfer from the carriers trapped at surface defect levels. The prototype device exhibits achromatic emission, with a chromaticity coordinate of (0.327, 0.330), and correlated color temperature similar to sunlight.An electrically driven quantum-dot hybrid white light-emitting diode is fabricated via spin coating CdSe quantum dots onto a GaN/ZnO nanorod matrix. For the first time, quantum dots are excited by fluorescence resonance energy transfer from the carriers trapped at surface defect levels. The prototype device exhibits achromatic emission, with a chromaticity coordinate of (0.327, 0.330), and correlated color temperature similar to sunlight. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr09261b

  14. Tunable full-color emitting BaMg2Al6Si9O30:Eu2+, Tb3+, Mn2+ phosphors based on energy transfer.

    PubMed

    Lü, Wei; Hao, Zhendong; Zhang, Xia; Luo, Yongshi; Wang, Xiaojun; Zhang, Jiahua

    2011-08-15

    A series of single-phase full-color emitting BaMg(2)Al(6)Si(9)O(30):Eu(2+), Tb(3+), Mn(2+) phosphors has been synthesized by solid-state reaction. Energy transfer from Eu(2+) to Tb(3+) and Eu(2+) to Mn(2+) in BaMg(2)Al(6)Si(9)O(30) host matrix is studied by luminescence spectra and energy-transfer efficiency and lifetimes. The wavelength-tunable white light can be realized by coupling the emission bands centered at 450, 542, and 610 nm ascribed to the contribution from Eu(2+) and Tb(3+) and Mn(2+), respectively. By properly tuning the relative composition of Tb(3+)/Mn(2+), chromaticity coordinates of (0.31, 0.30), high color rendering index R(a) = 90, and correlated color temperature (CCT) = 5374 K can be achieved upon excitation of UV light. Thermal quenching properties reveal that BaMg(2)Al(6)Si(9)O(30): Eu(2+), Tb(3+), Mn(2+) exhibits excellent characteristics even better than that of YAG:Ce. Our results indicate our white BaMg(2)Al(6)Si(9)O(30):Eu(2+), Tb(3+), Mn(2+) can serve as a key material for phosphor-converted light-emitting diode and fluorescent lamps. PMID:21766885

  15. Highly Efficient Simplified Single-Emitting-Layer Hybrid WOLEDs with Low Roll-off and Good Color Stability through Enhanced Förster Energy Transfer.

    PubMed

    Zhang, Dongdong; Cai, Minghan; Zhang, Yunge; Zhang, Deqiang; Duan, Lian

    2015-12-30

    Single-emitting layer hybrid white organic light-emitting diodes (SEL-hybrid-WOLEDs) usually suffer from low efficiency, significant roll-off, and poor color stability, attributed to the incomplete energy transfer from the triplet states of the blue fluorophores to the phosphors. Here, we demonstrate highly efficient SEL-hybrid-WOLEDs with low roll-off and good color-stability utilizing blue thermally activated delayed fluorescence (TADF) materials as the host emitters. The triplet states of the blue TADF host emitter can be up-converted into its singlet states, and then the energy is transferred to the complementary phosphors through the long-range Förster energy transfer, enhancing the energy transfer from the host to the dopant. Simplified SEL-hybrid-WOLEDs achieve the highest forward-viewing external quantum efficiency (EQE) of 20.8% and power efficiency of 51.2 lm/W with CIE coordinates of (0.398, 0.456) at a luminance of 500 cd/m(2). The device EQE only slightly drops to 19.6% at a practical luminance of 1000 cd/m(2) with a power efficiency of 38.7 lm/W. Furthermore, the spectra of the device are rather stable with the raising voltage. The reason can be assigned to the enhanced Förster energy transfer, wide charge recombination zone, as well as the bipolar charge transporting ability of the host emitter. We believe that our work may shed light on the future development of highly efficient SEL-hybrid-WOLEDs with simultaneous low roll-off and good color stability. PMID:26642836

  16. Giant strain-sensitivity of acoustic energy dissipation in solids containing dry and saturated cracks with wavy interfaces.

    PubMed

    Zaitsev, V Yu; Matveev, L A

    2012-01-01

    Mechanisms of acoustic energy dissipation in heterogeneous solids attract much attention in view of their importance for material characterization, nondestructive testing, and geophysics. Due to the progress in measurement techniques in recent years, it has been revealed that rocks can demonstrate extremely high strain sensitivity of seismoacoustic loss. In particular, it has been found that strains of order 10(-8) produced by lunar and solar tides are capable of causing variations in the seismoacoustic decrement on the order of several percent. Some laboratory data (although obtained for higher frequencies) also indicate the presence of very high dissipative nonlinearity. Conventionally discussed dissipation mechanisms (thermoelastic loss in dry solids, Biot and squirt-type loss in fluid-saturated ones) do not suffice to interpret such data. Here the dissipation at individual cracks is revised taking into account the influence of wavy asperities of their surfaces quite typical of real cracks, which can drastically change the values of the relaxation frequencies and can result in giant strain sensitivity of the dissipation without the necessity of assuming the presence of unrealistically thin (and, therefore, unrealistically soft) cracks. In particular, these mechanisms suggest interpretation for observations of pronounced amplitude modulation of seismo-acoustic waves by tidal strains. PMID:22280566

  17. Acoustic waves from mechanical impulses due to fluorescence resonant energy (Förster) transfer: Blowing a whistle with light

    NASA Astrophysics Data System (ADS)

    Zurita-Sánchez, J. R.; Henkel, C.

    2012-02-01

    We present a momentum transfer mechanism mediated by electromagnetic fields that originates in a system of two nearby molecules: one excited (donor D*) and the other in ground state (acceptor A). An intermolecular force related to fluorescence resonant energy or Förster transfer (FRET) arises in the unstable D*A molecular system, which differs from the equilibrium van der Waals interaction. Due to the its finite lifetime, a mechanical impulse is imparted to the relative motion in the system. We analyze the FRET impulse when the molecules are embedded in free space and find that its magnitude can be much greater than the single recoil photon momentum, getting comparable with the thermal momentum (Maxwell-Boltzmann distribution) at room temperature. In addition, we propose that this FRET impulse can be exploited in the generation of acoustic waves inside a film containing layers of donor and acceptor molecules, when a picosecond laser pulse excites the donors. This acoustic transient is distinguishable from that produced by thermal stress due to laser absorption, and may therefore play a role in photoacoustic spectroscopy. The effect can be seen as exciting a vibrating system like a string or organ pipe with light; it may be used as an opto-mechanical transducer.

  18. Finite element modeling of acoustic wave propagation and energy deposition in bone during extracorporeal shock wave treatment

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofeng; Matula, Thomas J.; Ma, Yong; Liu, Zheng; Tu, Juan; Guo, Xiasheng; Zhang, Dong

    2013-06-01

    It is well known that extracorporeal shock wave treatment is capable of providing a non-surgical and relatively pain free alternative treatment modality for patients suffering from musculoskeletal disorders but do not respond well to conservative treatments. The major objective of current work is to investigate how the shock wave (SW) field would change if a bony structure exists in the path of the acoustic wave. Here, a model of finite element method (FEM) was developed based on linear elasticity and acoustic propagation equations to examine SW propagation and deflection near a mimic musculoskeletal bone. High-speed photography experiments were performed to record cavitation bubbles generated in SW field with the presence of mimic bone. By comparing experimental and simulated results, the effectiveness of FEM model could be verified and strain energy distributions in the bone were also predicted according to numerical simulations. The results show that (1) the SW field will be deflected with the presence of bony structure and varying deflection angles can be observed as the bone shifted up in the z-direction relative to SW geometric focus (F2 focus); (2) SW deflection angels predicted by the FEM model agree well with experimental results obtained from high-speed photographs; and (3) temporal evolutions of strain energy distribution in the bone can also be evaluated based on FEM model, with varied vertical distance between F2 focus and intended target point on the bone surface. The present studies indicate that, by combining MRI/CT scans and FEM modeling work, it is possible to better understand SW propagation characteristics and energy deposition in musculoskeletal structure during extracorporeal shock wave treatment, which is important for standardizing the treatment dosage, optimizing treatment protocols, and even providing patient-specific treatment guidance in clinic.

  19. Investigation of energy transfer and charge trapping in dye-doped organic light-emitting diodes by magneto-electroluminescence measurement

    NASA Astrophysics Data System (ADS)

    Peng, Qiming; Gao, Na; Li, Weijun; Chen, Ping; Li, Feng; Ma, Yuguang

    2013-05-01

    We investigated the energy transfer and charge trapping (CT) in dye-doped organic light-emitting devices by using the magneto-electroluminescence as a tool. An intra-molecular charge-transfer fluorescent material N,N-diphenyl-4-(9-phenylnaphtho-[2,3-c][1,2,5]thiadiazol-4-yl)aniline was selected as the guest emitter. The tri-(8-hydroxyquinoline)-aluminum and 1,3-bis(9-carbazolyl)benzene were selected as the hosts. Our results demonstrate that as the energy difference between the HOMO (highest occupied molecular orbital)/LUMO (lowest unoccupied molecular orbital) of the host and the guest (ΔEHOMO/ΔELUMO) increases, the CT becomes more dominant, and the CT cannot be ignored even when the ΔEHOMO/ΔELUMO is small and the emission spectrum of the host overlaps the absorption spectrum of the guest well.

  20. Acoustic Noise Test Report for the U.S. Department of Energy 1.5-Megawatt Wind Turbine

    SciTech Connect

    Roadman, Jason; Huskey, Arlinda

    2015-07-01

    A series of tests were conducted to characterize the baseline properties and performance of the U.S. Department of Energy (DOE) 1.5-megawatt wind turbine (DOE 1.5) to enable research model development and quantify the effects of future turbine research modifications. The DOE 1.5 is built on the platform of GE's 1.5-MW SLE commercial wind turbine model. It was installed in a nonstandard configuration at the NWTC with the objective of supporting DOE Wind Program research initiatives such as A2e. Therefore, the test results may not represent the performance capabilities of other GE 1.5-MW SLE turbines. The acoustic noise test documented in this report is one of a series of tests carried out to establish a performance baseline for the DOE 1.5 in the NWTC inflow environment.

  1. The WiggleZ Dark Energy Survey: improved distance measurements to z = 1 with reconstruction of the baryonic acoustic feature

    NASA Astrophysics Data System (ADS)

    Kazin, Eyal A.; Koda, Jun; Blake, Chris; Padmanabhan, Nikhil; Brough, Sarah; Colless, Matthew; Contreras, Carlos; Couch, Warrick; Croom, Scott; Croton, Darren J.; Davis, Tamara M.; Drinkwater, Michael J.; Forster, Karl; Gilbank, David; Gladders, Mike; Glazebrook, Karl; Jelliffe, Ben; Jurek, Russell J.; Li, I.-hui; Madore, Barry; Martin, D. Christopher; Pimbblet, Kevin; Poole, Gregory B.; Pracy, Michael; Sharp, Rob; Wisnioski, Emily; Woods, David; Wyder, Ted K.; Yee, H. K. C.

    2014-07-01

    We present significant improvements in cosmic distance measurements from the WiggleZ Dark Energy Survey, achieved by applying the reconstruction of the baryonic acoustic feature technique. We show using both data and simulations that the reconstruction technique can often be effective despite patchiness of the survey, significant edge effects and shot-noise. We investigate three redshift bins in the redshift range 0.2 < z < 1, and in all three find improvement after reconstruction in the detection of the baryonic acoustic feature and its usage as a standard ruler. We measure model-independent distance measures DV(rsfid/rs) of 1716 ± 83, 2221 ± 101, 2516 ± 86 Mpc (68 per cent CL) at effective redshifts z = 0.44, 0.6, 0.73, respectively, where DV is the volume-averaged distance, and rs is the sound horizon at the end of the baryon drag epoch. These significantly improved 4.8, 4.5 and 3.4 per cent accuracy measurements are equivalent to those expected from surveys with up to 2.5 times the volume of WiggleZ without reconstruction applied. These measurements are fully consistent with cosmologies allowed by the analyses of the Planck Collaboration and the Sloan Digital Sky Survey. We provide the DV(rsfid/rs) posterior probability distributions and their covariances. When combining these measurements with temperature fluctuations measurements of Planck, the polarization of Wilkinson Microwave Anisotropy Probe 9, and the 6dF Galaxy Survey baryonic acoustic feature, we do not detect deviations from a flat Λ cold dark matter (ΛCDM) model. Assuming this model, we constrain the current expansion rate to H0 = 67.15 ± 0.98 km s-1Mpc-1. Allowing the equation of state of dark energy to vary, we obtain wDE = -1.080 ± 0.135. When assuming a curved ΛCDM model we obtain a curvature value of ΩK = -0.0043 ± 0.0047.

  2. Infrared emitting device and method

    DOEpatents

    Kurtz, Steven R.; Biefeld, Robert M.; Dawson, L. Ralph; Howard, Arnold J.; Baucom, Kevin C.

    1997-01-01

    An infrared emitting device and method. The infrared emitting device comprises a III-V compound semiconductor substrate upon which are grown a quantum-well active region having a plurality of quantum-well layers formed of a ternary alloy comprising InAsSb sandwiched between barrier layers formed of a ternary alloy having a smaller lattice constant and a larger energy bandgap than the quantum-well layers. The quantum-well layers are preferably compressively strained to increase the threshold energy for Auger recombination; and a method is provided for determining the preferred thickness for the quantum-well layers. Embodiments of the present invention are described having at least one cladding layer to increase the optical and carrier confinement in the active region, and to provide for waveguiding of the light generated within the active region. Examples have been set forth showing embodiments of the present invention as surface- and edge-emitting light emitting diodes (LEDs), an optically-pumped semiconductor laser, and an electrically-injected semiconductor diode laser. The light emission from each of the infrared emitting devices of the present invention is in the midwave infrared region of the spectrum from about 2 to 6 microns.

  3. Enhancing the Efficiency and Contrast Ratio of White Organic Light-Emitting Diode Using Energy-Recyclable Photovoltaic Cells

    NASA Astrophysics Data System (ADS)

    Yokoyama, Meiso; Wu, Chung-Ming; Su, Shui-Hsiang

    2012-03-01

    We demonstrate that power recycling is feasible by using a semitransparent strip of Al electrode as an interconnecting layer to merge a white organic light-emitting device (WOLED) and an organic photovoltaic (OPV) cell. The device is called a photovoltaic organic light-emitting device (PVOLED). It has a glass/indium tin oxide (ITO)/copper phthalocyanine (CuPc)/4,4,4-tris(3-methyl-phenylphenylamino) triphenylamine (m-MTDATA):V2O5/2-N',N-bis(1-naphthyl)-N,N'-diphenyl-1'-biphenyl-4,4'-diamine (NPB)/4,4'-bis(carbazol-9-yl)biphenyl (CBP):bis[3,5-difluoro-2-(2-pyridyl) phenyl-(2-carboxypyridyl)] iridium(II) (FIrpic):4-(dicyanomethylene)-2-t-butyl-6 (1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB)/4,7-diphenyl-1,10-phenanthroline (BPhen)/LiF/Al/poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61 butyric acid methyl ester (PCBM)/V2O5/Al structure. A power recycling efficiency of 10.133% is achieved using the WOLED of the PVOLED operated at 9 V and a brightness of 2110 cd/m2 when the conversion efficiency of the OPV cell is 2.3%. We found that the power recycling efficiency decreases at a high brightness and a high applied voltage owing to an increase in the input power of the WOLED. A high efficiency (18.3 cd/A) and a high contrast ratio (9.3) are obtained in the device operated at 2500 cd/m2 under an ambient illumination of 24000 lx. Reasonable white light emission with Commission Internationale De L'Eclairage (CIE) color coordinates of (0.32, 0.44) at 20 mA/cm2 and a slight color shift occur in spite of the high current density of 50 mA/cm2.

  4. A novel emitting color tunable phosphor Ba3Gd(PO4)3: Ce3+, Tb3+ based on energy transfer

    NASA Astrophysics Data System (ADS)

    Jin, Yahong; Hu, Yihua; Chen, Li; Wang, Xiaojuan; Mu, Zhongfei; Ju, Guifang; Yang, Zhongfu

    2014-03-01

    A novel emitting color tunable phosphor Ba3Gd(PO4)3: Ce3+, Tb3+ was synthesized by the traditional high temperature solid state reaction method. The photoluminescence (PL) and energy transfer (ET) properties of Ce3+ and Tb3+ doped Ba3Gd(PO4)3 host were studied in detail. The obtained phosphors show both a blue emission from Ce3+ and a yellowish-green emission from Tb3+ with considerable intensity under ultraviolet (UV) excitation (~310 nm). When the content of Ce3+ was fixed at 0.05, the emission chromaticity coordinates could be adjusted from blue to green region by tuning the contents of Tb3+ ions from 0.01 to 0.5 through an ET process. The critical distance between Ce3+ and Tb3+ is 16.16 Å. The ET mechanism from Ce3+ to Tb3+ ions was proved to be dipole-dipole interaction. The developed phosphor exhibits a strong excitation in UV spectral region and high efficient ET from Ce3+ to Tb3+ ions. It may find applications as a green light-emitting UV-convertible phosphor in white LED devices. Furthermore, a white light emission phosphor Ba3Gd(PO4)3: Ce3+, Tb3+, Mn2+ was also investigated.

  5. Energy- and time-resolved measurements of fast ions emitted from plasma-focus discharges by means of a Thomson spectrometer

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, R.; Czaus, K.; Paduch, M.; Sadowski, M. J.; Skladnik-Sadowska, E.; Zaloga, D. R.; Zielinska, E.; Żebrowski, J.

    2015-09-01

    The paper presents results of time-resolved measurements of fast deuterons emitted from high-current discharges of the Plasma-Focus (PF) type. The measurements were performed in a modified PF-1000U facility which is operated at the IFPiLM in Warsaw, Poland. The device was equipped with a fast-acting gas valve placed inside the inner electrode and oriented along the z-axis. The valve could inject a small volume of a chosen gas in front of this electrode. The PF discharges were initiated at the initial deuterium pressure equal to 1.6 or 2 hPa, with or without the use of the gas-puffing. Such discharges emitted intense beams of accelerated primary ions and X-ray pulses as well as products of nuclear fusion reactions. The reported measurements of the fast ion beams were performed by means of a Thomson-type spectrometer located at a chosen distance at the z-axis and equipped with miniature scintillation detectors. These detectors were placed in different points upon the deuteron parabola which corresponded to determined energy values. The detectors configuration allowed us to determine instants of the ion emission (using a TOF technique) and to compare them with instants of the X-ray emission. The collected data provided important information about emission characteristics of the modified PF-1000U facility.

  6. 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.

  7. 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

  8. Improved efficiency in blue phosphorescent organic light emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter

    SciTech Connect

    Swensen, James S.; Polikarpov, Evgueni; Von Ruden, Amber L.; Wang, Liang; Sapochak, Linda S.; Padmaperuma, Asanga B.

    2011-03-15

    Data from a series of phosphorescent blue organic light emitting devices OLEDs with emissive layers consisting of either CBP:6% Firpic or mCP:6% FIrpic show that the triplet energy of the hole and electron transport layers can have a larger influence on the external quantum efficiency of an operating OLED than the triplet energy of the host material. These results are important and insightful given the commonly held view that host materials for phosphorescent OLEDs must have a triplet energy higher than that of the emitter in order to obtain high external quantum efficiency (EQE). A new host material, 4-(di-ptolylaminophenyl)diphenylphosphine oxide (DHM-A2), which has a triplet energy less than that of FIrpic is also reported. OLEDs fabricated using DHM-A2 show improved performance (lower drive voltage and higher external quantum efficiency) over OLEDs using 4- (diphenylphosphoryl)-N,N-diphenylaniline (HMA1), a high performance ambipolar DHM-A2 analogue with a triplet energy greater than FIrpic. Our results suggest modified design rules for the development of new, high performance host materials., ames, more focus can be placed on molecular structures that provide good charge transport (i.e., ambipolarity for charge balance) and good molecular stability (for long lifetimes). This improved understanding provides additional flexibility in order to generate OLEDs with lower operating voltage and longer lifetime, while still providing high EQE.

  9. 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. ...

  10. 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.

  11. A hybrid approach for predicting the distribution of vibro-acoustic energy in complex built-up structures.

    PubMed

    Maksimov, Dmitrii N; Tanner, Gregor

    2011-09-01

    Finding the distribution of vibro-acoustic energy in complex built-up structures in the mid-to-high frequency regime is a difficult task. In particular, structures with large variation of local wavelengths and/or characteristic scales pose a challenge referred to as the mid-frequency problem. Standard numerical methods such as the finite element method (FEM) scale with the local wavelength and quickly become too large even for modern computer architectures. High frequency techniques, such as statistical energy analysis (SEA), often miss important information such as dominant resonance behavior due to stiff or small scale parts of the structure. Hybrid methods circumvent this problem by coupling FEM/BEM and SEA models in a given built-up structure. In the approach adopted here, the whole system is split into a number of subsystems that are treated by either FEM or SEA depending on the local wavelength. Subsystems with relative long wavelengths are modeled using FEM. Making a diffuse field assumption for the wave fields in the short wave length components, the coupling between subsystems can be reduced to a weighted random field correlation function. The approach presented results in an SEA-like set of linear equations that can be solved for the mean energies in the short wavelength subsystems. PMID:21895075

  12. Photon energy spectrum emitted by a novel polymer-encapsulated {sup 103}Pd source and its effect on the dose rate constant

    SciTech Connect

    Khan, Sabrina; Chen, Zhe Jay; Nath, Ravinder

    2008-04-15

    Two independent groups have published intrinsic dosimetry parameters for the recently introduced OptiSeed{sup 103} interstitial brachytherapy source which contains {sup 103}Pd encapsulated by a novel polymer shell. The dose rate constant ({lambda}) reported by the two groups, however, differed by more than 6% and there is currently no AAPM recommended consensus value for this source in clinical dosimetry. The aim of this work was to perform an independent determination of {lambda} for the OptiSeed{sup 103} source using a recently developed photon spectrometry technique. Three OptiSeed{sup 103} sources (model 1032P) with known air-kerma strength were used in this study. The photon energy spectrum emitted along the radial direction on the source's bisector was measured in air using a high-resolution intrinsic germanium spectrometer designed and established for low-energy brachytherapy source spectrometry. The dose rate constant of each source was determined from its emitted energy spectrum and the spatial distribution of radioactivity in the source. Unlike other sources made with traditional titanium encapsulation, the photons emitted by the OptiSeed{sup 103} sources exhibited only slight spectral hardening, yielding a relative energy spectrum closer to that emitted by bare {sup 103}Pd. The dose rate constant determined by the photon spectrometry technique for water was 0.664{+-}0.025 cGy h{sup -1} U{sup -1}. This value agreed, within experimental uncertainties, with the Monte Carlo-calculated value ({sub MC}{lambda}) of 0.665{+-}0.014 cGy h{sup -1} U{sup -1} and the TLD-measured value (with a Monte Carlo-calculated solid-phantom-to-water conversion factor) of 0.675{+-}0.051 cGy h{sup -1} U{sup -1} reported by Wang and Hertel [Appl. Radiat. Isot. 63, 311-321 (2005)]. However, it differed by -6.7% from the {sub MC}{lambda} of 0.712{+-}0.043 cGy h{sup -1} U{sup -1} reported by Bernard and Vynckier [Phys. Med. Biol. 50, 1493-1504 (2005)]. The results obtained in this

  13. RELEASE OF ELASTIC STRAIN ENERGY AS ACOUSTIC EMISSION DURING THE REVERSE THERMOELASTIC PHASE TRANSFORMATION IN Au-47.5 at.percent Cd ALLOY

    SciTech Connect

    Baram, J.; Avissar, J.; Gefen, Y.; Rosen, M.

    1980-05-01

    The objective of this paper is to present experimental evidence concerning the acoustic energy evolved during the heating and cooling phase changes in Au-47.5 at.% Cd polycrystals. The results are examined from the point of view of the stored elastic strain energy during the martensite formation, and the frictional work that is dissipated by the movement of martensite interfaces in either direction, upon heating and cooling.

  14. Electrochemiluminescence energy transfer-promoted ultrasensitive immunoassay using near-infrared-emitting CdSeTe/CdS/ZnS quantum dots and gold nanorods

    PubMed Central

    Li, Lingling; Chen, Ying; Lu, Qian; Ji, Jing; Shen, Yuanyuan; Xu, Mi; Fei, Rong; Yang, Guohai; Zhang, Kui; Zhang, Jian-Rong; Zhu, Jun-Jie

    2013-01-01

    The marriage of energy transfer with electrochemiluminescence has produced a new technology named electrochemiluminescence energy transfer (ECL-ET), which can realize effective and sensitive detection of biomolecules. To obtain optimal ECL-ET efficiency, perfect energy overlapped donor/acceptor pair is of great importance. Herein, we present a sensitive ECL-ET based immunosensor for the detection of tumor markers, using energy tunable CdSeTe/CdS/ZnS double shell quantum dots (QDs) and gold nanorods (GNRs) as the donor and acceptor, respectively. Firstly a facile microwave-assisted strategy for the synthesis of green- to near-infrared-emitting CdSeTe/CdS/ZnS QDs with time- and component-tunable photoluminescence was proposed. And, on the basis of the adjustable optical properties of both CdSeTe/CdS/ZnS QDs and GNRs, excellent overlap between donor emission and acceptor absorption can be obtained to ensure effective ECL-ET quenching, thus improving the sensing sensitivity. This method represents a novel approach for versatile detection of biomolecules at low concentrations. PMID:23524874

  15. Energy trapping of thickness-extensional modes in thin film bulk acoustic wave filters

    NASA Astrophysics Data System (ADS)

    Zhao, Zinan; Qian, Zhenghua; Wang, Bin

    2016-01-01

    This paper presents the thickness-extensional vibration of a rectangular piezoelectric thin film bulk acoustic wave filter with two pairs of electrodes symmetrically deposited on the center of the zinc oxide film. The two-dimensional scalar differential equations which were first derived to describe in-plane vibration distribution by Tiersten and Stevens are employed. The Ritz method with trigonometric functions as basis functions is used based on a variational formulation developed in our previous paper. Free vibration resonant frequencies and corresponding modes are obtained. The modes may separate into symmetric and antisymmetric ones for such a structurally symmetric filter. Trapped modes with vibrations mainly under the driving electrodes are exhibited. The six corner-type regions of the filter neglected by Tiersten and Stevens for an approximation are taken into account in our analysis. Results show that their approximation can lead to an inaccuracy on the order of dozens of ppm for the fundamental mode, which is quite significant in filter operation and application.

  16. Exclusive experiment on nuclei with backward emitted particles by electron-nucleus collision in {approximately} 10 GeV energy range

    SciTech Connect

    Saito, T.; Takagi, F.

    1994-04-01

    Since the evidence of strong cross section in proton-nucleus backward scattering was presented in the early of 1970 years, this phenomena have been interested from the point of view to be related to information on the short range correlation between nucleons or on high momentum components of the wave function of the nucleus. In the analysis of the first experiment on protons from the carbon target under bombardment by 1.5-5.7 GeV protons, indications are found of an effect analogous to scaling in high-energy interactions of elementary particles with protons. Moreover it is found that the function f(p{sup 2})/{sigma}{sub tot}, which describes the spectra of the protons and deuterons emitted backward from nuclei in the laboratory system, does not depend on the energy and the type of the incident particle or on the atomic number of the target nucleus. In the following experiments the spectra of the protons emitted from the nuclei C, Al, Ti, Cu, Cd and Pb were measured in the inclusive reactions with incident particles of negative pions (1.55-6.2 GeV/c) and protons (6.2-9.0 GeV/C). The cross section f is described by f = E/p{sup 2} d{sup 2}{sigma}/dpd{Omega} = C exp ({minus}Bp{sup 2}), where p is the momentum of hadron. The function f depends linearly on the atomic weight A of the target nuclei. The slope parameter B is independent of the target nucleus and of the sort and energy of the bombarding particles. The invariant cross section {rho} = f/{sigma}{sub tot} is also described by exponential A{sub 0} exp ({minus}A{sub 1p}{sup 2}), where p becomes independent of energy at initial particle energies {ge} 1.5 GeV for C nucleus and {ge} 5 GeV for the heaviest of the investigated Pb nuclei.

  17. 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.

  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. 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.

  20. 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.

  1. 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.

  2. Infrared emitting device and method

    DOEpatents

    Kurtz, S.R.; Biefeld, R.M.; Dawson, L.R.; Howard, A.J.; Baucom, K.C.

    1997-04-29

    The infrared emitting device comprises a III-V compound semiconductor substrate upon which are grown a quantum-well active region having a plurality of quantum-well layers formed of a ternary alloy comprising InAsSb sandwiched between barrier layers formed of a ternary alloy having a smaller lattice constant and a larger energy bandgap than the quantum-well layers. The quantum-well layers are preferably compressively strained to increase the threshold energy for Auger recombination; and a method is provided for determining the preferred thickness for the quantum-well layers. Embodiments of the present invention are described having at least one cladding layer to increase the optical and carrier confinement in the active region, and to provide for waveguiding of the light generated within the active region. Examples have been set forth showing embodiments of the present invention as surface- and edge-emitting light emitting diodes (LEDs), an optically-pumped semiconductor laser, and an electrically-injected semiconductor diode laser. The light emission from each of the infrared emitting devices of the present invention is in the midwave infrared region of the spectrum from about 2 to 6 microns. 8 figs.

  3. Search for discrete gamma-ray sources emitting at energies greater than 10/sup 15/ eV

    SciTech Connect

    Samorski, M.; Stamm, W.

    1984-02-15

    The data of the extensive air shower experiment at Kiel have been scanned systematically for possible discrete ..gamma..-ray sources in the energy range E>10/sup 15/ eV and in the declination band delta = 25/sup 0/-75/sup 0/. Photon fluxes for celestial positions with the statistically most significant excesses of showers and 3 sigma upper limit photon fluxes for COS B ..gamma..-ray sources visible to the extensive air shower experiment at Kiel are presented.

  4. Positive-energy D-bar method for acoustic tomography: a computational study

    NASA Astrophysics Data System (ADS)

    de Hoop, M. V.; Lassas, M.; Santacesaria, M.; Siltanen, S.; Tamminen, J. P.

    2016-02-01

    A new computational method for reconstructing a potential from the Dirichlet-to-Neumann (DN) map at positive energy is developed. The method is based on D-bar techniques and it works in absence of exceptional points—in particular, if the potential is small enough compared to the energy. Numerical tests reveal exceptional points for perturbed, radial potentials. Reconstructions for several potentials are computed using simulated DN maps with and without added noise. The new reconstruction method is shown to work well for energy values between 10-5 and 5, smaller values giving better results.

  5. Energy alignment and trap states in dye-doped tris-8-(hydroxyquinoline) aluminum light-emitting devices

    NASA Astrophysics Data System (ADS)

    Forsythe, Eric W.; Morton, David C.; Le, Quoc T.; Yan, Li; Nuesch, F.; Tang, Ching W.; Gao, Yongli

    1999-05-01

    Thermally stimulated luminescence has used to directly measure the trap states in intrinsic Alq3 and Alq3 doped with coumarin 6. For Alq3 doped with coumarin 6, we observe an increase in the trap energy from 0.25eV for undoped Alq3 to 0.32eV for doping concentrations as high as 2 percent. The origin of these trap states may be related to the relative energy level alignment between the Alq3 host and coumarin dopant. Using UV photoemission spectroscopy, we have measured the solid state energy alignment of the highest occupied molecular orbitals between Alq3 and coumarin 6. Finally, we report I-V curves for single layer devices as a function of doping with Al/LiF top and bottom contacts. The charge transport shows the trap states induced in the Alq3 films due to the presence of the coumarin 6 molecules decrease the carrier mobility and increase the energetic disorder. These results can be directly observed from the measured I-V curves.

  6. Acoustic streaming jets: A scaling and dimensional analysis

    SciTech Connect

    Botton, V. Henry, D.; Millet, S.; Ben-Hadid, H.; Garandet, J. P.

    2015-10-28

    We present our work on acoustic streaming free jets driven by ultrasonic beams in liquids. These jets are steady flows generated far from walls by progressive acoustic waves. As can be seen on figure 1, our set-up, denominated AStrID for Acoustic Streaming Investigation Device, is made of a water tank in which a 29 mm plane source emits continuous ultrasonic waves at typically 2 MHz. Our approach combines an experimental characterization of both the acoustic pressure field (hydrophone) and the obtained acoustic streaming velocity field (PIV visualization) on one hand, with CFD using an incompressible Navier-Stokes solver on the other hand.

  7. Vertical-cavity surface-emitting laser in the long-wavelength (700 nm) region in the visible by energy transfer between organic dyes

    NASA Astrophysics Data System (ADS)

    Liao, Zhifu; Zhou, Yuan; Cui, Yuanjing; Yang, Yu; Wang, Zhiyu; Qian, Guodong

    2014-06-01

    In this work, organic vertical-cavity surface-emitting lasers (VCSELs) with single-mode laser output in the long-wavelength region (~700 nm) of the visible were reported based on the energy transfer between dye pairs consisting of pyrromethene 597 (PM597) and rhodamine 700 (LD700). By co-doping PM597 into the polymeric hosts, the fluorescence intensity of LD700 was enhanced by 30-fold and the photophysical parameters of the donor-acceptor pairs were investigated, indicating the involvement of non-radiative resonance energy transfer processes between PM597 and LD700. Active distributed Bragg reflectors (DBR) were made by alternately spin-coating dye-doped polyvinylcarbazole and cellulose acetate thin films as the high and low refractive index layers, respectively. By sandwiching the active layer with 2 DBR mirrors, VCSEL emission at 698.9 nm in the biological first window (650-950 nm) was observed under the 532-nm laser pulses. The laser slope efficiency and threshold were also measured.

  8. Distinguishing triplet energy transfer and trap-assisted recombination in multi-color organic light-emitting diode with an ultrathin phosphorescent emissive layer

    SciTech Connect

    Xue, Qin Liu, Shouyin; Xie, Guohua; Chen, Ping; Zhao, Yi; Liu, Shiyong

    2014-03-21

    An ultrathin layer of deep-red phosphorescent emitter tris(1-phenylisoquinoline) iridium (III) (Ir(piq){sub 3}) is inserted within different positions of the electron blocking layer fac-tris (1-phenylpyrazolato-N,C{sup 2′})-iridium(III) (Ir(ppz){sub 3}) to distinguish the contribution of the emission from the triplet exciton energy transfer/diffusion from the adjacent blue phosphorescent emitter and the trap-assisted recombination from the narrow band-gap emitter itself. The charge trapping effect of the narrow band-gap deep-red emitter which forms a quantum-well-like structure also plays a role in shaping the electroluminescent characteristics of multi-color organic light-emitting diodes. By accurately controlling the position of the ultrathin sensing layer, it is considerably easy to balance the white emission which is quite challenging for full-color devices with multiple emission zones. There is nearly no energy transfer detectable if 7 nm thick Ir(ppz){sub 3} is inserted between the blue phosphorescent emitter and the ultrathin red emitter.

  9. Characterization of low-energy photon-emitting brachytherapy sources and kilovoltage x-ray beams using spectrometry

    NASA Astrophysics Data System (ADS)

    Moga, Jacqueline D.

    Low-energy photon sources are used in therapeutic radiation oncology for brachytherapy with low dose-rate (LDR) sources and for superficial and orthovoltage therapy with kilovolt-age x-ray beams. Current dosimetry methods for these sources utilize energy-integrating devices, such as thermoluminescent dosimeters and ionization chambers. This thesis work investigates the dosimetry of LDR brachytherapy sources and kilovoltage x-ray beams using spectrometry, which preserves the energy-specific source output. Several LDR brachytherapy source models were measured with a reverse-electrode germanium (REGe) detector. The measured spectra were corrected for MCNP5-calculated detector response using a deconvolution algorithm (Beach, 2005). The peak areas determined from the corrected spectra were used to calculate the dose-rate constant (Chen and Nath, 2001) and the air-kerma strength. Dose-rate constant results agreed well with the published values (Rivard et al., 2004; Chen and Nath, 2007). Air-kerma strength results were systematically 2%--5% low compared to calibration values and primary air-kerma strength measurements. The spectrometry methods for LDR brachytherapy sources offer a promising alternative to existing experimental techniques, but further work is necessary to improve agreement with the current air-kerma strength standard methodology. Spectra of 20kVp---250kVp x-ray beams were measured with a low-energy germanium detector (LEGe). The LEGe spectrometry system was modeled in MCNP5 to calculate a detector response function. Backward stripping, which showed less variability than deconvolution, was used for correcting the measured x-ray spectra. The corrected experimental spectra were compared to spectra from: (1) Monte Carlo simulations of the full x-ray tube with EGSnrc, (2) the SpekCalc program (Poludniowski et al., 2009), and (3) the Gesellschaft fur Strahlen-und Umweltforschung mbH Munchen (GSF) Report 560. Agreement was best for the UW60-M through UW150-M

  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. On neutron stars in f(R) theories: Small radii, large masses and large energy emitted in a merger

    NASA Astrophysics Data System (ADS)

    Aparicio Resco, Miguel; de la Cruz-Dombriz, Álvaro; Llanes Estrada, Felipe J.; Zapatero Castrillo, Víctor

    2016-09-01

    In the context of f(R) gravity theories, we show that the apparent mass of a neutron star as seen from an observer at infinity is numerically calculable but requires careful matching, first at the star's edge, between interior and exterior solutions, none of them being totally Schwarzschild-like but presenting instead small oscillations of the curvature scalar R; and second at large radii, where the Newtonian potential is used to identify the mass of the neutron star. We find that for the same equation of state, this mass definition is always larger than its general relativistic counterpart. We exemplify this with quadratic R2 and Hu-Sawicki-like modifications of the standard General Relativity action. Therefore, the finding of two-solar mass neutron stars basically imposes no constraint on stable f(R) theories. However, star radii are in general smaller than in General Relativity, which can give an observational handle on such classes of models at the astrophysical level. Both larger masses and smaller matter radii are due to much of the apparent effective energy residing in the outer metric for scalar-tensor theories. Finally, because the f(R) neutron star masses can be much larger than General Relativity counterparts, the total energy available for radiating gravitational waves could be of order several solar masses, and thus a merger of these stars constitutes an interesting wave source.

  12. 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.

  13. Measurement of inclusive spectra of protons emitted in interactions between /sup 12/C nuclei of energy 3. 6 GeV/nucleon and C, Cu, Sn, and Pb nuclei

    SciTech Connect

    Ad'yasevich, B.P.; Antonenko, V.G.; Vinogradov, A.A.; Grigor'yan, Y.I.; Ippolitov, M.S.; Karadzhev, K.V.; Lebedev, A.L.; Man'ko, V.I.; Nikolaev, S.A.; Polunin, Y.P.; Tsvetkov, A.A.

    1984-08-01

    The inclusive spectra of protons emitted when carbon ions of energy 3.6 GeV/nucleon are used to bombard C, Cu, Sn, and Pb targets are investigated. Data are presented on the invariant cross sections for proton emission in a wide range of emission angles and momenta. The observed empirical relations are discussed.

  14. 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.

  15. 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 ...

  16. 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.

  17. Dosimetric prerequisites for routine clinical use of photon emitting brachytherapy sources with average energy higher than 50 kev

    SciTech Connect

    Li Zuofeng; Das, Rupak K.; De Werd, Larry A.; Ibbott, Geoffrey S.; Meigooni, Ali S.; Perez-Calatayud, Jose; Rivard, Mark J.; Sloboda, Ronald S.; Williamson, Jeffrey F.

    2007-01-15

    This paper presents the recommendations of the American Association of Physicists in Medicine (AAPM) and the European Society for Therapeutic Radiology and Oncology (ESTRO) on the dosimetric parameters to be characterized, and dosimetric studies to be performed to obtain them, for brachytherapy sources with average energy higher than 50 keV that are intended for routine clinical use. In addition, this document makes recommendations on procedures to be used to maintain vendor source strength calibration accuracy. These recommendations reflect the guidance of the AAPM and the ESTRO for its members, and may also be used as guidance to vendors and regulatory agencies in developing good manufacturing practices for sources used in routine clinical treatments.

  18. I. Gas adsorption properties and porosity of transition metal-based cyanogels. II. Novel energy transfer processes in organic light-emitting devices

    NASA Astrophysics Data System (ADS)

    Deshpande, Rahul Shrikant

    organic light-emitting device (OLED) is demonstrated. This OLED is based on a novel mechanism of energy transfer termed interlayer sequential energy transfer. The relative red-, green-, and blue-emission intensities in this OLED can be independently tuned by the means of two separate parameters.

  19. Study of Harmonics-to-Noise Ratio and Critical-Band Energy Spectrum of Speech as Acoustic Indicators of Laryngeal and Voice Pathology

    NASA Astrophysics Data System (ADS)

    Shama, Kumara; krishna, Anantha; Cholayya, Niranjan U.

    2006-12-01

    Acoustic analysis of speech signals is a noninvasive technique that has been proved to be an effective tool for the objective support of vocal and voice disease screening. In the present study acoustic analysis of sustained vowels is considered. A simple[InlineEquation not available: see fulltext.]-means nearest neighbor classifier is designed to test the efficacy of a harmonics-to-noise ratio (HNR) measure and the critical-band energy spectrum of the voiced speech signal as tools for the detection of laryngeal pathologies. It groups the given voice signal sample into pathologic and normal. The voiced speech signal is decomposed into harmonic and noise components using an iterative signal extrapolation algorithm. The HNRs at four different frequency bands are estimated and used as features. Voiced speech is also filtered with 21 critical-bandpass filters that mimic the human auditory neurons. Normalized energies of these filter outputs are used as another set of features. The results obtained have shown that the HNR and the critical-band energy spectrum can be used to correlate laryngeal pathology and voice alteration, using previously classified voice samples. This method could be an additional acoustic indicator that supplements the clinical diagnostic features for voice evaluation.

  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. Broadband light-emitting diode

    DOEpatents

    Fritz, I.J.; Klem, J.F.; Hafich, M.J.

    1998-07-14

    A broadband light-emitting diode is disclosed. The broadband light-emitting diode (LED) comprises a plurality of III-V compound semiconductor layers grown on a semiconductor substrate, with the semiconductor layers including a pair of cladding layers sandwiched about a strained-quantum-well active region having a plurality of different energy bandgaps for generating light in a wavelength range of about 1.3--2 {micro}m. In one embodiment of the present invention, the active region may comprise a first-grown quantum-well layer and a last-grown quantum-well layer that are oppositely strained; whereas in another embodiment of the invention, the active region is formed from a short-period superlattice structure (i.e. a pseudo alloy) comprising alternating thin layers of InGaAs and InGaAlAs. The use a short-period superlattice structure for the active region allows different layers within the active region to be simply and accurately grown by repetitively opening and closing one or more shutters in an MBE growth apparatus to repetitively switch between different growth states therein. The broadband LED may be formed as either a surface-emitting LED or as an edge-emitting LED for use in applications such as chemical sensing, fiber optic gyroscopes, wavelength-divisionmultiplexed (WDM) fiber-optic data links, and WDM fiber-optic sensor networks for automobiles and aircraft. 10 figs.

  2. Broadband light-emitting diode

    DOEpatents

    Fritz, Ian J.; Klem, John F.; Hafich, Michael J.

    1998-01-01

    A broadband light-emitting diode. The broadband light-emitting diode (LED) comprises a plurality of III-V compound semiconductor layers grown on a semiconductor substrate, with the semiconductor layers including a pair of cladding layers sandwiched about a strained-quantum-well active region having a plurality of different energy bandgaps for generating light in a wavelength range of about 1.3-2 .mu.m. In one embodiment of the present invention, the active region may comprise a first-grown quantum-well layer and a last-grown quantum-well layer that are oppositely strained; whereas in another embodiment of the invention, the active region is formed from a short-period superlattice structure (i.e. a pseudo alloy) comprising alternating thin layers of InGaAs and InGaAlAs. The use a short-period superlattice structure for the active region allows different layers within the active region to be simply and accurately grown by repetitively opening and closing one or more shutters in an MBE growth apparatus to repetitively switch between different growth states therein. The broadband LED may be formed as either a surface-emitting LED or as an edge-emitting LED for use in applications such as chemical sensing, fiber optic gyroscopes, wavelength-division-multiplexed (WDM) fiber-optic data links, and WDM fiber-optic sensor networks for automobiles and aircraft.

  3. Toward fluorine-free blue-emitting cationic iridium complexes: to generate emission from the cyclometalating ligands with enhanced triplet energy.

    PubMed

    He, Lei; Wang, Zhen; Duan, Lian; Yang, Chunpeng; Tang, Ruiren; Song, Xiangzhi; Pan, Chunyue

    2016-04-01

    A route toward fluorine-free blue-emitting cationic iridium complexes, to generate emission from the cyclometalating ligands with enhanced triplet energy, has been proposed and demonstrated. Attaching electron-donating groups to the pyridine moieties of the ppy-type cyclometalating ligands (Hppy is 2-phenylpyridine) enhances the triplet ((3)π-π*) energy of the ligand, and the use of electron-rich or non-conjugated ancillary ligands ensures that the emission is generated from the (3)π-π* states of cyclometalating ligands. By this molecular design, [Ir(buoppy)2(pzpy)]PF6 (1) and [Ir(buoppy)2(bim-cb)]PF6 (2) have been developed, with 4-butoxy-2-phenylpyridine (buoppy) as the cyclometalating ligand and electron-rich 2-(1H-pyrazol-1-yl)pyridine (pzpy) or non-conjugated N-heterocyclic dicarbene (bim-cb) as the ancillary ligands. Complexes 1 and 2 give emission with major emission peaks around 465 nm, which is among the bluest reported for fluorine-free cationic iridium complexes. For both complexes, the emission is generated from the (3)π-π* states centered on buoppy. For complex 1, the charge-transfer (Ir/buoppy → pzpy) state is dominated by non-radiative deactivation and it behaves as a non-radiative deactivation channel for the emissive buoppy-centered (3)π-π* states which lies close to the charge-transfer state in energy. Such a non-radiative deactivation channel is largely suppressed in the rigid matrix, and is eliminated in complex 2 with a non-conjugated dicarbene ancillary ligand. PMID:26918443

  4. Injection current dependences of electroluminescence transition energy in InGaN/GaN multiple quantum wells light emitting diodes under pulsed current conditions

    SciTech Connect

    Zhang, Feng; Ikeda, Masao Liu, Jianping; Zhang, Shuming; Zhou, Kun; Yang, Hui; Liu, Zongshun

    2015-07-21

    Injection current dependences of electroluminescence transition energy in blue InGaN/GaN multiple quantum wells light emitting diodes (LEDs) with different quantum barrier thicknesses under pulsed current conditions have been analyzed taking into account the related effects including deformation caused by lattice strain, quantum confined Stark effects due to polarization field partly screened by carriers, band gap renormalization, Stokes-like shift due to compositional fluctuations which are supposed to be random alloy fluctuations in the sub-nanometer scale, band filling effect (Burstein-Moss shift), and quantum levels in finite triangular wells. The bandgap renormalization and band filling effect occurring at high concentrations oppose one another, however, the renormalization effect dominates in the concentration range studied, since the band filling effect arising from the filling in the tail states in the valence band of quantum wells is much smaller than the case in the bulk materials. In order to correlate the carrier densities with current densities, the nonradiative recombination rates were deduced experimentally by curve-fitting to the external quantum efficiencies. The transition energies in LEDs both with 15 nm quantum barriers and 5 nm quantum barriers, calculated using full strengths of theoretical macroscopic polarization given by Barnardini and Fiorentini [Phys. Status Solidi B 216, 391 (1999)] are in excellent accordance with experimental results. The LED with 5 nm barriers has been shown to exhibit a higher transition energy and a smaller blue shift than those of LED with 15 nm barriers, which is mainly caused by the smaller internal polarization field in the quantum wells.

  5. Alfvén acoustic channel for ion energy in high-beta tokamak plasmas.

    PubMed

    Bierwage, Andreas; Aiba, Nobuyuki; Shinohara, Kouji

    2015-01-01

    When the plasma beta (ratio of thermal to magnetic pressure) in the core of a tokamak is raised to values of several percent, as required for a thermonuclear fusion reactor, continuous spectra of long-wavelength slow magnetosonic waves enter the frequency band occupied by continuous spectra of shear Alfvén waves. It is found that these two branches can couple strongly, so that Alfvén modes that are resonantly driven by suprathermal ions transfer some of their energy to sound waves. Since sound waves are heavily damped by thermal ion Landau resonances, these results reveal a new energy channel that contributes to the damping of Alfvénic instabilities and the noncollisional heating of bulk ions, with potentially important consequences for confinement and fusion performance. PMID:25615474

  6. Alfvén Acoustic Channel for Ion Energy in High-Beta Tokamak Plasmas

    NASA Astrophysics Data System (ADS)

    Bierwage, Andreas; Aiba, Nobuyuki; Shinohara, Kouji

    2015-01-01

    When the plasma beta (ratio of thermal to magnetic pressure) in the core of a tokamak is raised to values of several percent, as required for a thermonuclear fusion reactor, continuous spectra of long-wavelength slow magnetosonic waves enter the frequency band occupied by continuous spectra of shear Alfvén waves. It is found that these two branches can couple strongly, so that Alfvén modes that are resonantly driven by suprathermal ions transfer some of their energy to sound waves. Since sound waves are heavily damped by thermal ion Landau resonances, these results reveal a new energy channel that contributes to the damping of Alfvénic instabilities and the noncollisional heating of bulk ions, with potentially important consequences for confinement and fusion performance.

  7. 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.

  8. Candidate X-ray-emitting OB Stars in the Carina Nebula Identified Via Infrared Spectral Energy Distributions

    NASA Astrophysics Data System (ADS)

    Povich, Matthew S.; Townsley, Leisa K.; Broos, Patrick S.; Gagné, Marc; Babler, Brian L.; Indebetouw, Rémy; Majewski, Steven R.; Meade, Marilyn R.; Getman, Konstantin V.; Robitaille, Thomas P.; Townsend, Richard H. D.

    2011-05-01

    We report the results of a new survey of massive, OB stars throughout the Carina Nebula using the X-ray point source catalog provided by the Chandra Carina Complex Project (CCCP) in conjunction with infrared (IR) photometry from the Two Micron All-Sky Survey and the Spitzer Space Telescope Vela-Carina survey. Mid-IR photometry is relatively unaffected by extinction, hence it provides strong constraints on the luminosities of OB stars, assuming that their association with the Carina Nebula, and hence their distance, is confirmed. We fit model stellar atmospheres to the optical (UBV) and IR spectral energy distributions (SEDs) of 182 OB stars with known spectral types and measure the bolometric luminosity and extinction for each star. We find that the extinction law measured toward the OB stars has two components: AV = 1-1.5 mag produced by foreground dust with a ratio of total-to-selective absorption RV = 3.1 plus a contribution from local dust with RV > 4.0 in the Carina molecular clouds that increases as AV increases. Using X-ray emission as a strong indicator of association with Carina, we identify 94 candidate OB stars with L bol >~ 104 L sun by fitting their IR SEDs. If the candidate OB stars are eventually confirmed by follow-up spectroscopic observations, the number of cataloged OB stars in the Carina Nebula will increase by ~50%. Correcting for incompleteness due to OB stars falling below the L bol cutoff or the CCCP detection limit, these results potentially double the size of the young massive stellar population.

  9. 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.

  10. Broadband Yellowish-Green Emitting Ba4Gd3Na3(PO4)6F2:Eu(2+) Phosphor: Structure Refinement, Energy Transfer, and Thermal Stability.

    PubMed

    Fu, Xiaopeng; Lü, Wei; Jiao, Mengmeng; You, Hongpeng

    2016-06-20

    A series of Ba4Gd3Na3(PO4)6F2:Eu(2+) phosphors with a broad emitting band have been synthesized by a traditional solid state reaction. The crystal structural and photoluminescence properties of Ba4Gd3Na3(PO4)6F2:Eu(2+) are investigated. The different crystallographic sites of Eu(2+) in Ba4Gd3Na3(PO4)6F2:Eu(2+) phosphors have been verified by means of their photoluminescence (PL) properties and decay times. Energy transfer between Eu(2+) ions, analyzed by excitation, emission, and PL decay behavior, has been indicated to be a dipole-dipole mechanism. Moreover, the luminescence quantum yield as well as the thermal stability of the Ba4Gd3Na3(PO4)6F2:Eu(2+) phosphor have been investigated systematically. The as-prepared Ba4Gd3Na3(PO4)6F2:Eu(2+) phosphor can act as a promising candidate for n-UV convertible white LEDs. PMID:27249557

  11. Effects of light-emitting diodes under capped daily energy consumption with combinations of electric power and photoperiod on cultivation of Chlorella pyrenoidosa.

    PubMed

    Li, Jinhao; Bin, Hui; Lin, Jian; Chen, Feng; Miao, Xiaoling

    2016-04-01

    Effects of white light-emitting diodes (LEDs) with different light intensities at photoperiod of 18:6h on Chlorella pyrenoidosa growth were investigated. The microalgae exhibited the highest growth rate 89.0mgL(-1)d(-1) and growth efficiency 97.8mgL(-1)KWh(-1) at 110 and 90μmolm(-2)s(-1), respectively. Based on the discovery of this asynchronous phenomenon between growth rate and growth efficiency, influences of LEDs (red, blue and white) under capped daily energy consumption (0.80KWh d(-1)) with combinations of electric power (33.3, 44.4 and 66.6w) and photoperiod (24:0, 18:6 and 12:12h) were further investigated. The highest growth efficiency 106.4mgL(-1)KWh(-1) and growth rate 85.1mgL(-1)d(-1) were both obtained under white-33.3w-24h. Growth efficiency and growth rate were simultaneously improved 1.1 times through this method above. The order of growth efficiency under different LEDs were white>blue>red. PMID:26826572

  12. In situ investigation of energy transfer in hybrid organic/colloidal quantum dot light-emitting diodes via magneto-electroluminescence.

    PubMed

    Chen, Lixiang; Chen, Qiusong; Lei, Yanlian; Jia, Weiyao; Yuan, De; Xiong, Zuhong

    2016-08-10

    Energy transfer (ET) and charge injection (CI) in the hybrid organic/colloidal quantum dot light-emitting diodes (QD-LEDs) have been investigated by using magneto-electroluminescence (MEL) as an in situ tool. The feasibility and availability of MEL as an in situ tool were systematically demonstrated in the typical QD-LEDs based on CdSe-ZnS core-shell QDs. Our results suggest that the ET and CI processes can be well discerned by MEL measurements since these two processes exhibit distinct responses to the applied magnetic field. Through measurement of the MEL and current efficiency, we indicated that ET would be the main mechanism for light emission in the present hybrid QD-LEDs. This study strongly suggests that MEL could be a highly sensitive fingerprint for ET, which provides a facile and efficient method for the in situ investigation of fundamental processes in hybrid organic/colloidal QD-LEDs and other organic/inorganic composites. PMID:27461412

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. Acoustic energy density distribution and sound intensity vector field inside coupled spaces.

    PubMed

    Meissner, Mirosław

    2012-07-01

    In this paper, the modal expansion method supported by a computer implementation has been used to predict steady-state distributions of the potential and kinetic energy densities, and the active and reactive sound intensities inside two coupled enclosures. The numerical study was dedicated to low-frequency room responses. Calculation results have shown that the distribution of energetic quantities in coupled spaces is strongly influenced by the modal localization. Appropriate descriptors of the localization effect were introduced to identify localized modes. As was evidenced by numerical data, the characteristic objects in the active intensity field are vortices positioned irregularly inside the room. It was found that vortex centers lie exactly on the lines corresponding to zeros of the eigenfunction for a dominant mode. Finally, an impact of the wall impedance on the quantitative relationship between the active and reactive intensities was analyzed and it was concluded that for very small sound damping the behavior of the sound intensity inside the room space is essentially only oscillatory. PMID:22779472

  19. A systematic evaluation of the dose-rate constant determined by photon spectrometry for twenty-one different models of low energy photon-emitting brachytherapy sources

    PubMed Central

    Chen, Zhe (Jay); Nath, Ravinder

    2012-01-01

    Purpose To perform a systematic comparison of the dose-rate constant (Λ) determined by the photon spectrometry technique (PST) with the consensus value (CONΛ) recommended by the American Association of Physicist in Medicine (AAPM) for twenty-one low energy photon-emitting interstitial brachytherapy sources. Method and Materials A total of 63 interstitial brachytherapy sources (21 different models with 3 sources per model) containing either 125I (14 models), 103Pd (6 models), or 131Cs (one model) were included in this study. A photon spectrometry technique (Med. Phys. 34, 1412-1430, 2007) was used to determine the dose-rate constant (PSTΛ) for each source model. Source-dependent variations in PSTΛ were analyzed systematically against the spectral characteristics of the emitted photons and the consensus values recommended by the AAPM brachytherapy subcommittee. Results The values of PSTΛ for the encapsulated sources of 103Pd, 125I, and 131Cs varied from 0.661 cGyh-1U-1 to 0.678 cGyh-1U-1, 0.959 cGyh-1U-1 to 1.024 cGyh-1U-1, and 1.066 cGyh-1U-1 to 1.073 cGyh-1U-1, respectively. The relative variation in PSTΛ among the six 103Pd source models, caused by variations in photon attenuation and in spatial distributions of radioactivity among the source models, was less than 3%. Greater variations in PSTΛ were observed among the fourteen 125I source models; the maximum relative difference was over 6%. These variations were caused primarily by the presence of silver in some 125I source models and, to a lesser degree, by the variations in photon attenuation and in spatial distribution of radioactivity among the source models. The presence of silver generates additional fluorescent x-rays with lower photon energies which caused the PSTΛ value to vary from 0.959 cGyh-1U-1 to 1.019 cGyh-1U-1 depending on the amount of silver used by a given source model. For those 125I sources that contain no silver, their PSTΛ was less variable and had values within 1% of 1.024 cGyh-1U

  20. 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.

  1. Body Morphology, Energy Stores, and Muscle Enzyme Activity Explain Cricket Acoustic Mate Attraction Signaling Variation

    PubMed Central

    Thomson, Ian R.; Darveau, Charles-A.; Bertram, Susan M.

    2014-01-01

    High mating success in animals is often dependent on males signalling attractively with high effort. Since males should be selected to maximize their reproductive success, female preferences for these traits should result in minimal signal variation persisting in the population. However, extensive signal variation persists. The genic capture hypothesis proposes genetic variation persists because fitness-conferring traits depend on an individual's basic processes, including underlying physiological, morphological, and biochemical traits, which are themselves genetically variable. To explore the traits underlying signal variation, we quantified among-male differences in signalling, morphology, energy stores, and the activities of key enzymes associated with signalling muscle metabolism in two species of crickets, Gryllus assimilis (chirper: <20 pulses/chirp) and G. texensis (triller: >20 pulses/chirp). Chirping G. assimilis primarily fuelled signalling with carbohydrate metabolism: smaller individuals and individuals with increased thoracic glycogen stores signalled for mates with greater effort; individuals with greater glycogen phosphorylase activity produced more attractive mating signals. Conversely, the more energetic trilling G. texensis fuelled signalling with both lipid and carbohydrate metabolism: individuals with increased β-hydroxyacyl-CoA dehydrogenase activity and increased thoracic free carbohydrate content signalled for mates with greater effort; individuals with higher thoracic and abdominal carbohydrate content and higher abdominal lipid stores produced more attractive signals. Our findings suggest variation in male reproductive success may be driven by hidden physiological trade-offs that affect the ability to uptake, retain, and use essential nutrients, although the results remain correlational in nature. Our findings indicate that a physiological perspective may help us to understand some of the causes of variation in behaviour. PMID:24608102

  2. Photochemistry of Organic Light-Emitting Diodes

    SciTech Connect

    Ehara, Masahiro; Nakatsuji, Hiroshi

    2007-12-26

    The optical properties and excited-state geometries of some organic light-emitting diodes have been investigated by the SAC-CI method. The absorption and emission spectra have been predicted in high accuracy and the chain-length dependence of transition energies has been precisely reproduced. The present study provides the useful basis for the theoretical design predicting the photo-physical properties of the organic light-emitting diodes.

  3. Light-emitting Diodes

    PubMed Central

    Opel, Daniel R.; Hagstrom, Erika; Pace, Aaron K.; Sisto, Krisanne; Hirano-Ali, Stefanie A.; Desai, Shraddha

    2015-01-01

    Background: In the early 1990s, the biological significance of light-emitting diodes was realized. Since this discovery, various light sources have been investigated for their cutaneous effects. Study design: A Medline search was performed on light-emitting diode lights and their therapeutic effects between 1996 and 2010. Additionally, an open-label, investigator-blinded study was performed using a yellow light-emitting diode device to treat acne, rosacea, photoaging, alopecia areata, and androgenetic alopecia. Results: The authors identified several case-based reports, small case series, and a few randomized controlled trials evaluating the use of four different wavelengths of light-emitting diodes. These devices were classified as red, blue, yellow, or infrared, and covered a wide range of clinical applications. The 21 patients the authors treated had mixed results regarding patient satisfaction and pre- and post-treatment evaluation of improvement in clinical appearance. Conclusion: Review of the literature revealed that differing wavelengths of light-emitting diode devices have many beneficial effects, including wound healing, acne treatment, sunburn prevention, phototherapy for facial rhytides, and skin rejuvenation. The authors’ clinical experience with a specific yellow light-emitting diode device was mixed, depending on the condition being treated, and was likely influenced by the device parameters. PMID:26155326

  4. An apparatus for measuring the energy and angular distribution of secondary electrons emitted from water vapor by fast heavy-ion impact

    NASA Astrophysics Data System (ADS)

    Ohsawa, Daisuke; Kawauchi, Hidetaka; Hirabayashi, Masataka; Okada, Yuki; Honma, Toshihiro; Higashi, Akio; Amano, Shigeru; Hashimoto, Yoshinori; Soga, Fuminori; Sato, Yukio

    2005-01-01

    An apparatus has been built to measure the doubly differential cross-section of electron emission from water vapor with fast heavy-ion impact (6-25 MeV/u). Ejected electrons are detected by a Chevron-type microchannel plate assembly after being analyzed by a 45° inclined parallel-plate electrostatic spectrometer, which is rotatable from 20° to 160° with respect to the incident-beam direction. The scattering chamber is made of iron, and both the electron spectrometer and the detector assembly are mounted in a μ-metal housing in order to suppress the effects of stray magnetic fields (including that of Earth). Water vapor is emitted into the interaction region from a nozzle of 1 × 15 mm2 aperture, and is instantly frozen and trapped as ice on a stainless-steel panel, which is cooled by liquid N2. With this water-vapor generation and collection system, a stable water-vapor jet (10-2-10-3 Torr) was obtained without deteriorating the pressure in the scattering chamber (∼4 × 10-7 Torr with a vapor flow of 40.0 cc/min). Using the present apparatus, we have successfully measured the energy and angular distribution (7-10,000 eV and 20-160°) of secondary electrons produced in the collision of a 6.0-MeV/u He2+ ion with water vapor; binary-encounter collision peaks were clearly observed at the several keV region for angles smaller than 90°, as well as the K-LL Auger peak of oxygen at ∼500 eV for all angles.

  5. A superconducting qubit coupled to propagating acoustic waves

    NASA Astrophysics Data System (ADS)

    Gustafsson, Martin V.; Aref, Thomas; Frisk Kockum, Anton; Ekström, Maria K.; Johansson, Göran; Delsing, Per

    2015-03-01

    Mechanical devices in the quantum regime have so far consisted mainly of suspended resonators, where standing modes can be populated with quanta of vibrational energy. We present a fundamentally different system, where the mechanical excitation is not restricted to a specific mode and location. Instead, we demonstrate strong non-classical coupling between propagating phonons and a superconducting qubit. The qubit is fabricated on a piezoelectric substrate, and is designed to interact with Surface Acoustic Waves (SAWs) in the gigahertz frequency range. A separate on-chip transducer allows us to launch SAWs toward the qubit from a distance and pick up SAW phonons that the qubit reflects and emits. In a series of experiments where the qubit is addressed both electrically and acoustically, we show that the qubit couples much more strongly to SAWs than to any electrical modes. The low speed of sound sets phonons apart from photons as a medium for transporting quantum information, and should enable real-time manipulation of propagating quanta. The short acoustic wavelength and strong piezoelectric coupling should also allows regimes of interaction to be explored which cannot be reached in photonic systems.

  6. 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

  7. 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

  8. Characterization of granular collapse onto hard substrates by acoustic emissions

    NASA Astrophysics Data System (ADS)

    Farin, Maxime; Mangeney, Anne; Toussaint, Renaud; De Rosny, Julien

    2013-04-01

    Brittle deformation in granular porous media can generate gravitational instabilities such as debris flows and rock avalanches. These phenomena constitute a major natural hazard for the population in mountainous, volcanic and coastal areas but their direct observation on the field is very dangerous. Recent studies showed that gravitational instabilities can be detected and characterized (volume, duration,...) thanks to the seismic signal they generate. In an avalanche, individual block bouncing and rolling on the ground are expected to generated signals of higher frequencies than the main flow spreading. The identification of the time/frequency signature of individual blocks in the recorded signal remains however difficult. Laboratory experiments were conducted to investigate the acoustic signature of diverse simple sources corresponding to grains falling over thin plates of plexiglas and rock blocks. The elastic energy emitted by a single bouncing steel bead into the support was first quantitatively estimated and compared to the potential energy of fall and to the potential energy change during the shock. Next, we consider the collapse of granular columns made of steel spherical beads onto hard substrates. Initially, these columns were held by a magnetic field allowing to suppress suddenly the cohesion between the beads, and thus to minimize friction effects that would arise from side walls. We varied systematically the column volume, the column aspect ratio (height over length) and the grain size. This is shown to affect the signal envelope and frequency content. In the experiments, two types of acoustic sensors were used to record the signals in a wide frequency range: accelerometers (1 Hz to 56 kHz) and piezoelectric sensors (100 kHz to 1 MHz). The experiments were also monitored optically using fast cameras. We developed a technique to use quantitatively both types of sensors to evaluate the elastic energy emitted by the sources. Eventually, we looked at what

  9. 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.

  10. 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.

  11. The ATM kinase signaling induced by the low-energy β-particles emitted by (33)P is essential for the suppression of chromosome aberrations and is greater than that induced by the energetic β-particles emitted by (32)P.

    PubMed

    White, Jason S; Yue, Ning; Hu, Jing; Bakkenist, Christopher J

    2011-03-15

    Ataxia-telangiectasia mutated (ATM) encodes a nuclear serine/threonine protein kinase whose activity is increased in cells exposed to low doses of ionizing radiation (IR). Here we examine ATM kinase activation in cells exposed to either (32)P- or (33)P-orthophosphate under conditions typically employed in metabolic labelling experiments. We calculate that the absorbed dose of IR delivered to a 5cm×5cm monolayer of cells incubated in 2ml media containing 1mCi of the high-energy (1.70MeV) β-particle emitter (32)P-orthophosphate for 30min is ∼1Gy IR. The absorbed dose of IR following an otherwise identical exposure to the low-energy (0.24MeV) β-particle emitter (33)P-orthophosphate is ∼0.18Gy IR. We show that low-energy β-particles emitted by (33)P induce a greater number of ionizing radiation-induced foci (IRIF) and greater ATM kinase signaling than energetic β-particles emitted by (32)P. Hence, we demonstrate that it is inappropriate to use (33)P-orthophosphate as a negative control for (32)P-orthophosphate in experiments investigating DNA damage responses to DNA double-strand breaks (DSBs). Significantly, we show that ATM accumulates in the chromatin fraction when ATM kinase activity is inhibited during exposure to either radionuclide. Finally, we also show that chromosome aberrations accumulate in cells when ATM kinase activity is inhibited during exposure to ∼0.36Gy β-particles emitted by (33)P. We therefore propose that direct cellular exposure to (33)P-orthophosphate is an excellent means to induce and label the IR-induced, ATM kinase-dependent phosphoproteome. PMID:21315088

  12. Acoustically assisted spin-transfer-torque switching of nanomagnets: An energy-efficient hybrid writing scheme for non-volatile memory

    SciTech Connect

    Biswas, Ayan K.; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

    2013-12-02

    We show that the energy dissipated to write bits in spin-transfer-torque random access memory can be reduced by an order of magnitude if a surface acoustic wave (SAW) is launched underneath the magneto-tunneling junctions (MTJs) storing the bits. The SAW-generated strain rotates the magnetization of every MTJs' soft magnet from the easy towards the hard axis, whereupon passage of a small spin-polarized current through a target MTJ selectively switches it to the desired state with > 99.99% probability at room temperature, thereby writing the bit. The other MTJs return to their original states at the completion of the SAW cycle.

  13. Light emitting ceramic device

    DOEpatents

    Valentine, Paul; Edwards, Doreen D.; Walker, Jr., William John; Slack, Lyle H.; Brown, Wayne Douglas; Osborne, Cathy; Norton, Michael; Begley, Richard

    2010-05-18

    A light-emitting ceramic based panel, hereafter termed "electroceramescent" panel, is herein claimed. The electroceramescent panel is formed on a substrate providing mechanical support as well as serving as the base electrode for the device. One or more semiconductive ceramic layers directly overlay the substrate, and electrical conductivity and ionic diffusion are controlled. Light emitting regions overlay the semiconductive ceramic layers, and said regions consist sequentially of a layer of a ceramic insulation layer and an electroluminescent layer, comprised of doped phosphors or the equivalent. One or more conductive top electrode layers having optically transmissive areas overlay the light emitting regions, and a multi-layered top barrier cover comprising one or more optically transmissive non-combustible insulation layers overlay said top electrode regions.

  14. Time reverse modeling of acoustic emissions in a reinforced concrete beam.

    PubMed

    Kocur, Georg Karl; Saenger, Erik H; Grosse, Christian U; Vogel, Thomas

    2016-02-01

    The time reverse modeling (TRM) is applied for signal-based acoustic emission (AE) analysis of reinforced concrete (RC) specimens. TRM uses signals obtained from physical experiments as input. The signals are re-emitted numerically into a structure in a time-reversed manner, where the wavefronts interfere and appear as dominant concentrations of energy at the origin of the AE. The experimental and numerical results presented for selected AE signals confirm that TRM is capable of localizing AE activity in RC caused by concrete cracking. The accuracy of the TRM results is corroborated by three-dimensional crack distributions obtained from X-ray computed tomography images. PMID:26518525

  15. Airbursts as a viable source of seismic and acoustic energy for the 2016 InSight geophysical lander mission to Mars: analysis using terrestrial analogues

    NASA Astrophysics Data System (ADS)

    Taylor, Jennifer; Wookey, James; Teanby, Nick

    2014-05-01

    The explosion of a bolide as a terminal airburst, before impact into a planetary surface, is a well-documented source of both seismic and acoustic energy[1]. Here we aim to define some diagnostic properties of a recorded airburst time-series and determine detectability criteria for such events for a single station seismo-acoustic station on the Martian surface. In 2016 NASA will launch the InSight geophysical monitoring system. This lander will carry in its SEIS payload two 3-component seismic instruments - the Short Period (SP) and Very Broadband (VBB) seismometers, as well as a micro-barometer for measurement of atmospheric pressure fluctuations. The SEIS and MB packages aboard InSight could potentially be used together for seismo-acoustic detection of impact or airburst events. In past studies, this technique has been used to analyse and model the Washington State Bolide[2] and, more recently, the Chelyabinsk fireball in 2013[3]. Using a multi-station array, it is possible to estimate total kinetic energy of a bolide, its line-of-sight direction and the approximate time of its terminal burst[4]. However, with only a single station, as would be the case on Mars, more creative methods must be employed to extract information from the event. We explore the diagnostic waveform properties of an airburst, including various arrivals from the event. We also show how dominant frequency changes with distance from the event, altitude and yield. Several terrestrial events are analysed, including the 2013 Chelyabinsk fireball. We present theoretical calculations of the likely proportion of bolide terminal bursts on Mars relative to impacts, based on differences in the structure and composition of the Martian atmosphere. We go on to predict the seismic arrivals that may be observed by InSight from the coupling of the acoustic blast into the Martian crust. It is hoped that these diagnostic tools will be useful to identify and quantify bolide terminal bursts on Mars over the

  16. 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.

  17. 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.}

  18. 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.

  19. Size Distribution of Sperm Whales Acoustically Identified during Long Term Deep-Sea Monitoring in the Ionian Sea.

    PubMed

    Caruso, Francesco; Sciacca, Virginia; Bellia, Giorgio; De Domenico, Emilio; Larosa, Giuseppina; Papale, Elena; Pellegrino, Carmelo; Pulvirenti, Sara; Riccobene, Giorgio; Simeone, Francesco; Speziale, Fabrizio; Viola, Salvatore; Pavan, Gianni

    2015-01-01

    The sperm whale (Physeter macrocephalus) emits a typical short acoustic signal, defined as a "click", almost continuously while diving. It is produced in different time patterns to acoustically explore the environment and communicate with conspecifics. Each emitted click has a multi-pulse structure, resulting from the production of the sound within the sperm whale's head. A Stable Inter Pulse Interval (Stable IPI) can be identified among the pulses that compose a single click. Applying specific algorithms, the measurement of this interval provides useful information to assess the total length of the animal recorded. In January 2005, a cabled hydrophone array was deployed at a depth of 2,100 m in the Central Mediterranean Sea, 25 km offshore Catania (Ionian Sea). The acoustic antenna, named OνDE (Ocean noise Detection Experiment), was in operation until November 2006. OνDE provided real time acoustic data used to perform Passive Acoustic Monitoring (PAM) of cetacean sound emissions. In this work, an innovative approach was applied to automatically measure the Stable IPI of the clicks, performing a cepstrum analysis to the energy (square amplitude) of the signals. About 2,100 five-minute recordings were processed to study the size distribution of the sperm whales detected during the OνDE long term deep-sea acoustic monitoring. Stable IPIs were measured in the range between 2.1 ms and 6.4 ms. The equations of Gordon (1991) and of Growcott (2011) were used to convert the IPIs into measures of size. The results revealed that the sperm whales recorded were distributed in length from about 7.5 m to 14 m. The size category most represented was from 9 m to 12 m (adult females or juvenile males) and specimens longer than 14 m (old males) seemed to be absent. PMID:26675588

  20. Size Distribution of Sperm Whales Acoustically Identified during Long Term Deep-Sea Monitoring in the Ionian Sea

    PubMed Central

    Caruso, Francesco; Sciacca, Virginia; Bellia, Giorgio; De Domenico, Emilio; Larosa, Giuseppina; Papale, Elena; Pellegrino, Carmelo; Pulvirenti, Sara; Riccobene, Giorgio; Simeone, Francesco; Speziale, Fabrizio; Viola, Salvatore; Pavan, Gianni

    2015-01-01

    The sperm whale (Physeter macrocephalus) emits a typical short acoustic signal, defined as a “click”, almost continuously while diving. It is produced in different time patterns to acoustically explore the environment and communicate with conspecifics. Each emitted click has a multi-pulse structure, resulting from the production of the sound within the sperm whale’s head. A Stable Inter Pulse Interval (Stable IPI) can be identified among the pulses that compose a single click. Applying specific algorithms, the measurement of this interval provides useful information to assess the total length of the animal recorded. In January 2005, a cabled hydrophone array was deployed at a depth of 2,100 m in the Central Mediterranean Sea, 25 km offshore Catania (Ionian Sea). The acoustic antenna, named OνDE (Ocean noise Detection Experiment), was in operation until November 2006. OνDE provided real time acoustic data used to perform Passive Acoustic Monitoring (PAM) of cetacean sound emissions. In this work, an innovative approach was applied to automatically measure the Stable IPI of the clicks, performing a cepstrum analysis to the energy (square amplitude) of the signals. About 2,100 five-minute recordings were processed to study the size distribution of the sperm whales detected during the OνDE long term deep-sea acoustic monitoring. Stable IPIs were measured in the range between 2.1 ms and 6.4 ms. The equations of Gordon (1991) and of Growcott (2011) were used to convert the IPIs into measures of size. The results revealed that the sperm whales recorded were distributed in length from about 7.5 m to 14 m. The size category most represented was from 9 m to 12 m (adult females or juvenile males) and specimens longer than 14 m (old males) seemed to be absent. PMID:26675588

  1. To stack or not to stack: Spectral energy distribution properties of Lyα-emitting galaxies at z = 2.1

    SciTech Connect

    Vargas, Carlos J.; Bish, Hannah; Gawiser, Eric; Kurczynski, Peter; Acquaviva, Viviana; Finkelstein, Steven L.; Ciardullo, Robin; Gronwall, Caryl; Hagen, Alex; Ashby, Matthew L. N.; Feldmeier, John; Ferguson, Henry; Koekemoer, Anton; Guaita, Lucia; Newman, Jeffrey A.; Padilla, Nelson

    2014-03-01

    We use the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) GOODS-S multi-wavelength catalog to identify counterparts for 20 Lyα emitting (LAE) galaxies at z = 2.1. We build several types of stacked spectral energy distributions (SEDs) of these objects. We combine photometry to form average and median flux-stacked SEDs, and postage-stamp images to form average and median image-stacked SEDs. We also introduce scaled flux stacks that eliminate the influence of variation in overall brightness. We use the SED fitting code SpeedyMC to constrain the physical properties of individual objects and stacks. Our LAEs at z = 2.1 have stellar masses ranging from 2 × 10{sup 7} M {sub ☉} to 8 × 10{sup 9} M {sub ☉} (median = 3 × 10{sup 8} M {sub ☉}), ages ranging from 4 Myr to 500 Myr (median = 100 Myr), and E(B – V) between 0.02 and 0.24 (median = 0.12). Although still low, this represents significantly more dust reddening than has been reported for LAEs at higher redshifts. We do not observe strong correlations between Lyα equivalent width (EW) and age or E(B – V). The Lyα radiative transfer (q) factors of our sample are predominantly close to one and do not correlate strongly with EW or E(B – V). The absence of strong correlations with EW or q implies that Lyα radiative transfer is highly anisotropic and/or prevents Lyα photons from scattering in dusty regions. The SED parameters of the flux stacks match the average and median values of the individual objects, with the flux-scaled median SED performing best with uncertainties reduced by a factor of two. Median image-stacked SEDs provide a poor representation of the median individual object, and none of the stacking methods capture the large dispersion of LAE properties.

  2. An Ultra-Low Power and Flexible Acoustic Modem Design to Develop Energy-Efficient Underwater Sensor Networks

    PubMed Central

    Sánchez, Antonio; Blanc, Sara; Yuste, Pedro; Perles, Angel; Serrano, Juan José

    2012-01-01

    This paper is focused on the description of the physical layer of a new acoustic modem called ITACA. The modem architecture includes as a major novelty an ultra-low power asynchronous wake-up system implementation for underwater acoustic transmission that is based on a low-cost off-the-shelf RFID peripheral integrated circuit. This feature enables a reduced power dissipation of 10 μW in stand-by mode and registers very low power values during reception and transmission. The modem also incorporates clear channel assessment (CCA) to support CSMA-based medium access control (MAC) layer protocols. The design is part of a compact platform for a long-life short/medium range underwater wireless sensor network. PMID:22969324

  3. 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.

  4. Light-Emitting Pickles

    ERIC Educational Resources Information Center

    Vollmer, M.; Mollmann, K-P.

    2015-01-01

    We present experiments giving new insights into the classical light-emitting pickle experiment. In particular, measurements of the spectra and temperatures, as well as high-speed recordings, reveal that light emission is connected to the polarity of the electrodes and the presence of hydrogen.

  5. Red Emitting VCSEL

    NASA Astrophysics Data System (ADS)

    Jetter, Michael; Roßbach, Robert; Michler, Peter

    This chapter describes the progress in development of vertical-cavity surface-emitting lasers (VCSEL) emitting in the red spectral region around 650 nm for data transmission over polymer optical fibers (POF). First, growth issues of red VCSEL using two different material systems, namely AlGaAs and AlGaInP, are introduced. In particular, the optical and electrical state-of-the-art characteristics as low threshold currents ({≤} 1 mA) and high output powers (several mW) are presented with a special focus on emission wavelength. Also the thermal budget and heat removal in the devices are pointed out with regard to the geometry of the VCSEL. Small-signal modulation response in terms of maximum resonance frequency in dependance on temperature behavior are discussed. Applications of these devices in optical interconnects are described and digital data transmission at data rates up to 2.1 Gbit/s over step-index POF is reported. These properties make red emitting VCSEL perfectly suited for high-speed low power consuming light sources for optical data communication via POF. By introducing InP quantum dots as gain material in red emitting VCSEL nearly temperature independent record low threshold current densities of around 10 A/cm2 could be observed.

  6. Light-emitting pickles

    NASA Astrophysics Data System (ADS)

    Vollmer, M.; Möllmann, K.-P.

    2015-01-01

    We present experiments giving new insights into the classical light-emitting pickle experiment. In particular, measurements of the spectra and temperatures, as well as high-speed recordings, reveal that light emission is connected to the polarity of the electrodes and the presence of hydrogen.

  7. Quality Prediction of Twin Wire Arc Sprayed Coatings Using Acoustic Emission Analysis

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Abdulgader, M.; Wang, G.; Zielke, R.

    2013-03-01

    In this work, acoustic emission analysis is utilized in the twin wire arc spraying (TWAS) process to study the influence of the adjustable process parameters on the simultaneously obtained acoustic signals at the nozzle and at the substrate. The amplitude of recorded signals at the substrate was in general much higher than those recorded at the nozzle. At the substrate side, the amplitude of emitted acoustic signals is dependent on feedstock materials and is higher when using solid wires. The acoustic signals were recorded at the spraying gun for different gas pressures without arc ignition (as dry runs) in order to reveal the effect of the arc on the emitted acoustic signals. A correlation between controllable parameters, the acoustic signals, and the obtained in-flight particle characteristics was observed. This work contributes to the online control of TWAS processes and is one of many proposed publications in the research field of the conducted acoustic emission analysis.

  8. A New Approach to Energy Integral for Investigation of Dust—Ion Acoustic (DIA) Waves in Multi-Component Plasmas with Quantum Effects in Inertia Less Electrons

    NASA Astrophysics Data System (ADS)

    Kalita, B. C.; Kalita, R.

    2015-06-01

    Dust-ion acoustic waves are investigated in this model of plasma consisting of negatively charged dusts, cold ions and inertia less quantum effected electrons with the help of a typical energy integral. In this case, a new technique is applied formulating a differential equation to establish the energy integral in case of multi-component plasmas which is not possible in general. Dust-ion acoustic (DIA) compressive and rarefactive, supersonic and subsonic solitons of various amplitudes are established. The consideration of smaller order nonlinearity in support of the newly established quantum plasma model is observed to generate small amplitude solitons at the decrease of Mach number. The growths of soliton amplitudes and potential depths are found more sensitive to the density of quantum electrons. The small density ratio r(= 1 - f) with a little quantized electrons supplemented by the dust charges Zd and the in-deterministic new quantum parameter C2 are found responsible to finally support the generation of small amplitude solitons admissible for the model.

  9. Applications of adaptive focused acoustics to compound management.

    PubMed

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

    2009-06-01

    Since the introduction of lithotripsy kidney stone therapy, Focused Acoustics and its properties have been thoroughly utilized in medicine and exploration. More recently, Compound Management is exploring its applications and benefits to sample integrity. There are 2 forms of Focused Acoustics: Acoustic Droplet Ejection and Adaptive Focused Acoustics, which work by emitting high-powered acoustic waves through water toward a focused point. This focused power results in noncontact plate-to-plate sample transfer or sample dissolution, respectively. For the purposes of this article, only Adaptive Focused Acoustics will be addressed. Adaptive Focused Acoustics uses high-powered acoustic waves to mix, homogenize, dissolve, and thaw samples. It facilitates transferable samples through noncontact, closed-container, isothermal mixing. Experimental results show significantly reduced mixing times, limited degradation, and ideal use for heat-sensitive compounds. Upon implementation, acoustic dissolution has reduced the number of samples requiring longer mixing times as well as reducing the number impacted by incomplete compound dissolution. It has also helped in increasing the overall sample concentration from 6 to 8 mM to 8 to 10 mM by ensuring complete compound solubilization. The application of Adaptive Focused Acoustics, however, cannot be applied to all Compound Management processes, such as sample thawing and low-volume sample reconstitution. This article will go on to describe the areas where Adaptive Focused Acoustics adds value as well as areas in which it has shown no clear benefit. PMID:19487768

  10. Robotic vehicle uses acoustic sensors for voice detection and diagnostics

    NASA Astrophysics Data System (ADS)

    Young, Stuart H.; Scanlon, Michael V.

    2000-07-01

    An acoustic sensor array that cues an imaging system on a small tele- operated robotic vehicle was used to detect human voice and activity inside a building. The advantage of acoustic sensors is that it is a non-line of sight (NLOS) sensing technology that can augment traditional LOS sensors such as visible and IR cameras. Acoustic energy emitted from a target, such as from a person, weapon, or radio, will travel through walls and smoke, around corners, and down corridors, whereas these obstructions would cripple an imaging detection system. The hardware developed and tested used an array of eight microphones to detect the loudest direction and automatically setter a camera's pan/tilt toward the noise centroid. This type of system has applicability for counter sniper applications, building clearing, and search/rescue. Data presented will be time-frequency representations showing voice detected within rooms and down hallways at various ranges. Another benefit of acoustics is that it provides the tele-operator some situational awareness clues via low-bandwidth transmission of raw audio data for the operator to interpret with either headphones or through time-frequency analysis. This data can be useful to recognize familiar sounds that might indicate the presence of personnel, such as talking, equipment, movement noise, etc. The same array also detects the sounds of the robot it is mounted on, and can be useful for engine diagnostics and trouble shooting, or for self-noise emanations for stealthy travel. Data presented will characterize vehicle self noise over various surfaces such as tiles, carpets, pavement, sidewalk, and grass. Vehicle diagnostic sounds will indicate a slipping clutch and repeated unexpected application of emergency braking mechanism.

  11. 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.

  12. Acoustic particle palpation for measuring tissue elasticity

    PubMed Central

    Koruk, Hasan; El Ghamrawy, Ahmed

    2015-01-01

    We propose acoustic particle palpation—the use of sound to press a population of acoustic particles against an interface—as a method for measuring the qualitative and quantitative mechanical properties of materials. We tested the feasibility of this method by emitting ultrasound pulses across a tunnel of an elastic material filled with microbubbles. Ultrasound stimulated the microbubble cloud to move in the direction of wave propagation, press against the distal surface, and cause deformations relevant for elasticity measurements. Shear waves propagated away from the palpation site with a velocity that was used to estimate the material's Young's modulus. PMID:26869723

  13. Acoustic particle palpation for measuring tissue elasticity

    NASA Astrophysics Data System (ADS)

    Koruk, Hasan; El Ghamrawy, Ahmed; Pouliopoulos, Antonios N.; Choi, James J.

    2015-11-01

    We propose acoustic particle palpation—the use of sound to press a population of acoustic particles against an interface—as a method for measuring the qualitative and quantitative mechanical properties of materials. We tested the feasibility of this method by emitting ultrasound pulses across a tunnel of an elastic material filled with microbubbles. Ultrasound stimulated the microbubble cloud to move in the direction of wave propagation, press against the distal surface, and cause deformations relevant for elasticity measurements. Shear waves propagated away from the palpation site with a velocity that was used to estimate the material's Young's modulus.

  14. 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

  15. 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.

  16. Review of organic light-emitting diodes with thermally activated delayed fluorescence emitters for energy-efficient sustainable light sources and displays

    NASA Astrophysics Data System (ADS)

    Volz, Daniel

    2016-04-01

    Thermally activated delayed fluorescence (TADF) is an emerging hot topic. Even though this photophysical mechanism itself has been described more than 50 years ago and optoelectronic devices with organic matter have been studied, improved, and even commercialized for decades now, the realization of the potential of TADF organic light-emitting diodes (OLEDs) happened only recently. TADF has been proven to be an attractive and very efficient alternative for phosphorescent materials, such as dopants in OLEDs, light-emitting electrochemical cells as well as potent emitters for chemiluminescence. In this review, the TADF concept is introduced in terms that are also understandable for nonchemists. The basic concepts behind this mechanism as well as state-of-the-art examples are discussed. In addition, the future economic impact, especially for the lighting and display market, is addressed here. We conclude that TADF materials are especially helpful to realize efficient, durable deep blue and white displays.

  17. Operational Performance Analysis of Passive Acoustic Monitoring for Killer Whales

    SciTech Connect

    Matzner, Shari; Fu, Tao; Ren, Huiying; Deng, Zhiqun; Sun, Yannan; Carlson, Thomas J.

    2011-09-30

    For the planned tidal turbine site in Puget Sound, WA, the main concern is to protect Southern Resident Killer Whales (SRKW) due to their Endangered Species Act status. A passive acoustic monitoring system is proposed because the whales emit vocalizations that can be detected by a passive system. The algorithm for detection is implemented in two stages. The first stage is an energy detector designed to detect candidate signals. The second stage is a spectral classifier that is designed to reduce false alarms. The evaluation presented here of the detection algorithm incorporates behavioral models of the species of interest, environmental models of noise levels and potential false alarm sources to provide a realistic characterization of expected operational performance.

  18. White light emitting diodes

    NASA Astrophysics Data System (ADS)

    Baur, J.; Schlotter, P.; Schneider, J.

    Using blue-emitting GaN LEDs on SiC substrate chips as primary light sources, we have fabricated green, yellow, red and white light emitting diodes (LUCOLEDs). The generation of mixed colors, as turquoise and magenta, is also demonstrated. The underlying physical principle is that of luminescence downconversion (Stokes shift), as typical for organic dye molecules and many inorganic phosphors. For white light generation via the LUCOLED principle, the phosphor Y3Al5O12:Ce3+(4f1) is ideally suited. The optical characteristics of Ce3+(4f1) in Y3Al5O12(YAG) are discussed in detail. Possibilities to "tune" the white color by various substitutions in the garnet lattice are shortly outlined.

  19. A compact array calibrator to study the feasibility of acoustic neutrino detection

    NASA Astrophysics Data System (ADS)

    Ardid, M.; Camarena, F.; Felis, I.; Herrero, A.; Llorens, C. D.; Martínez-Mora, J.; Saldaña, M.

    2016-04-01

    Underwater acoustic detection of ultra-high-energy neutrinos was proposed already in 1950s: when a neutrino interacts with a nucleus in water, the resulting particle cascade produces a pressure pulse that has a bipolar temporal structure and propagates within a flat disk-like volume. A telescope that consists of thousands of acoustic sensors deployed in the deep sea can monitor hundreds of cubic kilometres of water looking for these signals and discriminating them from acoustic noise. To study the feasibility of the technique it is critical to have a calibrator able to mimic the neutrino "signature" that can be operated from a vessel. Due to the axial-symmetry of the signal, their very directive short bipolar shape and the constraints of operating at sea, the development of such a calibrator is very challenging. Once the possibility of using the acoustic parametric technique for this aim was validated with the first compact array calibrator prototype, in this paper we describe the new design for such a calibrator composed of an array of piezo ceramic tube transducers emitting in axial direction.

  20. Wide-band excited Y6(WMo)(0.5)O12:Eu red phosphor for white light emitting diode: structure evolution, photoluminescence properties, and energy transfer mechanisms involved.

    PubMed

    Li, Huaiyong; Noh, Hyeon Mi; Moon, Byung Kee; Choi, Byung Chun; Jeong, Jung Hyun; Jang, Kiwan; Lee, Ho Sueb; Yi, Soung Soo

    2013-10-01

    Y6(WMo)(0.5)O12 activated with Eu(3+) ions was investigated as a red-emitting conversion phosphor for white light emitting diodes (WLEDs). The phosphors were synthesized by calcining a citrate-complexation precursor at different temperatures. The photoluminescence properties of the phosphors and the energy transfer mechanisms involved were studied as a function of structure evolution. It was found that the host lattices were crystallized in a cubic or a hexagonal phase depending on the synthesis conditions. Although all the phosphors showed intensive red emission under an excitation of near-UV or blue light due to energy transfer from the host lattices to Eu(3+) ions, the photoluminescence spectra and temporal decay features were found to vary significantly with the structure and crystallinity of the host lattice. The mechanisms of the energy transfer from the host lattices to Eu(3+) ions and energy quenching among Eu(3+) ions were discussed on the basis of structure evolution of the host lattice. Phosphors calcined at 800 and 1300 °C were suggested to be promising candidates for blue and near-UV light excited WLEDs, respectively. PMID:24041150

  1. Luminescence properties and energy transfer in the novel red emitting phosphors Ba2Ln(BO3)2Cl:Sm3+, Eu3+ (Ln=Y, Gd)

    NASA Astrophysics Data System (ADS)

    Fan, Yan; Hu, Yihua; Chen, Li; Wang, Xiaojuan; Ju, Guifang

    2014-10-01

    A series of Sm3+/Eu3+ singly and co-doped Ba2Ln(BO3)2Cl (Ln=Y3+, Gd3+) phosphors were prepared via the solid-state method. The XRD results indicate that the as-prepared products keep the monoclinic structure with a P21/m space group of Ba2Ln(BO3)2Cl, which belongs to the isomorphic substitution for Ln3+ sites in the Ba2Yb(BO3)2Cl host. The photoluminescence (PL) spectra demonstrate that Ba2Ln(BO3)2Cl:Sm3+,Eu3+ emits red light centered at 593 nm under the 393 nm excitation which is in good agreement with the emission wavelength from near ultraviolet light-emitting diodes (LEDs). The luminescence decays suggest that the energy transfer from Sm3+ to Eu3+ ions in Ba2Ln(BO3)2Cl:Eu3+, Sm3+ occurs. All results mean that Ba2Ln(BO3)2Cl:Eu3+, Sm3+ phosphors exhibit potential to act as a kind of red phosphor for near ultraviolet white light-emitting diodes (w-LEDs).

  2. 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.

  3. 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.

  4. Acoustic waves in a stratified atmosphere. IV. Three-dimensional nonlinear hydrodynamics

    NASA Astrophysics Data System (ADS)

    Kalkofen, W.; Rossi, P.; Bodo, G.; Massaglia, S.

    2010-09-01

    Context. The quiet solar chromosphere in the interior of supergranulation cells is believed to be heated by the dissipation of acoustic waves that originate with a typical period of 3 min in the photosphere. Aims: We investigate how the horizontal expansion with height of acoustic waves traveling upward into an isothermal, gravitationally stratified atmosphere depends on the size of the source region. Methods: We have solved the three-dimensional, nonlinear, time-dependent hydrodynamic equations for impulsively-generated, upward-propagating acoustic waves, assuming cylindrical symmetry. Results: When the diameter of the source of acoustic waves is small, the pattern of the upward-propagating waves is that of a point source, for which the energy travels upward in a vertical cone, qualitatively matching the observed pattern of bright-point expansion with height. For the largest plausible size of a source region, i.e., with granular size of 1 Mm, wave propagation in the low chromosphere is approximately that of plane waves, but in the middle and upper chromosphere it is also that of a point source. The assumption of plane-wave propagation is not a good approximation in the solar chromosphere. The upward-directed energy flux is larger than that of the solar chromosphere, at least in the middle and upper chromosphere, and probably throughout. Conclusions: Simulations of impulsively generated acoustic waves emitted from source regions with diameters that are small compared to the pressure scale height of the atmosphere qualitatively reproduce the upward expansion observed in chromospheric bright points. The emission features in the cores of the H and K lines are predicted to be blueshifted for a pulse and redshifted for the waves in its wake. The contribution of internal gravity waves to the upward energy flux is small and decreases with increasing size of the source region.

  5. Producing Metallic Glasses With Acoustic Leviation

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Feng, I. A.

    1983-01-01

    Acoustic fields support and cool liquid particles. Levitated by sound energy, liquid drop in acoustic standing-wave field surrounded by acousticically-induced jet streams. Streaming gas cools drow below its freezing point in small fraction of second. Allows new amorphous alloys including "metallic glass" to be formed.

  6. 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.

  7. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S.

    2000-01-01

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

  8. 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.

  9. Measurement of the spectra of doubly charged particles emitted in bombardment of lead nuclei by. cap alpha. particles with energy 3. 6 GeV/nucleon

    SciTech Connect

    Ad'yasevich, B.P.; Antonenko, V.G.; Vinogradov, A.A.; Grigor'yan, Y.I.; Dukhanov, V.I.; Ippolitov, M.S.; Karadzhev, K.V.; Lebedev, A.L.; Man'ko, V.I.; Nikolaev, S.A.; Polunin, Y.P.; Tsvetkov, A.A.

    1983-12-01

    We have measured the spectra of double charged particles emitted in interaction of 3.6 GeV/nucleon ..cap alpha.. particles with lead nuclei. Spectra were measured at emission angles from 10 to 95/sup 0/ in the range of secondary-particle velocities 0.37<..beta..<0.55. Angular distributions were obtained, the total cross section for emission of doubly charged particles was evaluated, and the ratios of the contributions of doubly and singly charged particles were determined. The rapidity distributions of the invariant cross sections for production of doubly charged particles reveal maxima at a rapidity yroughly-equal0.15--0.20.

  10. 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

  11. 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

  12. 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.

  13. Light emitting elastomer compositions and method of use

    DOEpatents

    McElhanon, James R.; Zifer, Thomas; Whinnery, LeRoy L.

    2004-11-23

    There is provided a light emitting device comprising a plurality of triboluminescent particles dispersed throughout an elastomeric body and activated by deforming the body in order to transfer mechanical energy to some portion of the particles. The light emitted by these mechanically excited particles is collected and directed into a light conduit and transmitted to a detector/indicator means.

  14. 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

  15. Silicon Carbide Terahertz Emitting Devices

    NASA Astrophysics Data System (ADS)

    Xuan, G.; Lv, P.-C.; Zhang, X.; Kolodzey, J.; Desalvo, G.; Powell, A.

    2008-05-01

    In recent years, terahertz (THz) sources between 0.1 THz and 10 THz have attracted much attention for imaging and sensing applications. THz emission from radiative transitions in impurity states has been demonstrated in Si and Ge devices by either electrical or optical pumping. Compared to Si as the material for THz emission, the wide-band-gap material SiC exhibits several advantages such as a higher dopant ionization energy, which allows a higher device operating temperature. Combining with its superior material qualities such as high breakdown field and high thermal conductivity, SiC is a promising material for high-temperature and high-power THz emitting devices. This article describes recent progress in using SiC materials to increase the operating temperature and output power of dopant-based THz sources.

  16. Convergent acoustic field of view in echolocating bats.

    PubMed

    Jakobsen, Lasse; Ratcliffe, John M; Surlykke, Annemarie

    2013-01-01

    Most echolocating bats exhibit a strong correlation between body size and the frequency of maximum energy in their echolocation calls (peak frequency), with smaller species using signals of higher frequency than larger ones. Size-signal allometry or acoustic detection constraints imposed on wavelength by preferred prey size have been used to explain this relationship. Here we propose the hypothesis that smaller bats emit higher frequencies to achieve directional sonar beams, and that variable beam width is critical for bats. Shorter wavelengths relative to the size of the emitter translate into more directional sound beams. Therefore, bats that emit their calls through their mouths should show a relationship between mouth size and wavelength, driving smaller bats to signals of higher frequency. We found that in a flight room mimicking a closed habitat, six aerial hawking vespertilionid species (ranging in size from 4 to 21 g, ref. 5) produced sonar beams of extraordinarily similar shape and volume. Each species had a directivity index of 11 ± 1 dB (a half-amplitude angle of approximately 37°) and an on-axis sound level of 108 ± 4 dB sound pressure level referenced to 20 μPa root mean square at 10 cm. Thus all bats adapted their calls to achieve similar acoustic fields of view. We propose that the necessity for high directionality has been a key constraint on the evolution of echolocation, which explains the relationship between bat size and echolocation call frequency. Our results suggest that echolocation is a dynamic system that allows different species, regardless of their body size, to converge on optimal fields of view in response to habitat and task. PMID:23172147

  17. A theoretical study of the feasibility of acoustical tweezers: Ray acoustics approach

    NASA Astrophysics Data System (ADS)

    Lee, Jungwoo; Ha, Kanglyeol; Shung, K. Kirk

    2005-05-01

    The optical tweezer has been found to have many biomedical applications in trapping macromolecules and cells. For the trapping mechanism, there has to be a sharp spatial change in axial optical intensity and the particle size must be much greater than the wavelength. Similar phenomenon may exist in acoustics. This work was undertaken to demonstrate theoretically that it is possible to acoustically trap particles near the focal point where most of the acoustic energy is concentrated if certain conditions are met. Acoustic force exerted on a fluid particle in ultrasonic fields is analyzed in a ray acoustics regime where the wavelength of acoustic beam is much smaller than the size of the particle. In order to apply the acoustical tweezer to manipulating macromolecules and cells whose size is in the order of a few microns or less, a prerequisite is that the ultrasound wavelength has to be much smaller than a few microns. In this paper, the analysis is therefore based on the field pattern produced by a strongly focused 100 MHz ultrasonic transducer with Gaussian intensity distribution. For the realization of acoustic trapping, negative axial radiation force has to be generated to pull a particle towards a focus. The fat particle considered for acoustic trapping in this paper has an acoustic impedance of 1.4 MRayls. The magnitude of the acoustic axial radiation force that has been calculated as the size of the fat particle is varied from 8λ to 14λ. In addition, both Fresnel coefficients at various positions are also calculated to assess the interaction of reflection and refraction and their relative contribution to the effect of the acoustical tweezer. The simulation results show that the feasibility of the acoustical tweezer depends on both the degree of acoustic impedance mismatch and the degree of focusing relative to the particle size. .

  18. Acoustic black holes: massless scalar field analytic solutions and analogue Hawking radiation

    NASA Astrophysics Data System (ADS)

    Vieira, H. S.; Bezerra, V. B.

    2016-07-01

    We obtain the analytic solutions of the radial part of the massless Klein-Gordon equation in the spacetime of both three dimensional rotating and four dimensional canonical acoustic black holes, which are given in terms of the confluent Heun functions. From these solutions, we obtain the scalar waves near the acoustic horizon. We discuss the analogue Hawking radiation of massless scalar particles and the features of the spectrum associated with the radiation emitted by these acoustic black holes.

  19. Pyrene-Oxadiazoles for Organic Light-Emitting Diodes: Triplet to Singlet Energy Transfer and Role of Hole-Injection/Hole-Blocking Materials.

    PubMed

    Chidirala, Swetha; Ulla, Hidayath; Valaboju, Anusha; Kiran, M Raveendra; Mohanty, Maneesha Esther; Satyanarayan, M N; Umesh, G; Bhanuprakash, Kotamarthi; Rao, Vaidya Jayathirtha

    2016-01-15

    Three pyrene-oxadiazole derivatives were synthesized and characterized by optical, electrochemical, thermal, and theoretical investigations to obtain efficient multifunctional organic light emitting diode (OLED) materials. Synthesized molecules were used as emitters and electron transporters in three different device configurations, involving hole-injection/hole-blocking materials that showed good current and power efficiencies. To understand the underlying mechanisms involved in the application of these molecules as emitters and transporters, a detailed photophysical characterization of molecules 4-6 was carried out. The absorption, steady-state fluorescence, phosphorescence, fluorescence lifetime, and phosphorescence lifetime measurements were carried out. The high quantum yield and efficient reverse intersystem crossing leading to delayed fluorescence emission makes the molecule a good emitter, and the charge delocalization properties leading to excimer formation make them efficient electron transporters. Isoenergetic singlet and triplet states of the molecules make the reverse intersystem crossing feasible at room temperature even in the absence of thermal activation. PMID:26651353

  20. 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.

  1. Power output and efficiency of beta-emitting microspheres

    NASA Astrophysics Data System (ADS)

    Cheneler, David; Ward, Michael

    2015-01-01

    Current standard methods to calculate the dose of radiation emitted during medical applications by beta-minus emitting microspheres rely on an over-simplistic formalism. This formalism is a function of the average activity of the radioisotope used and the physiological dimensions of the patient only. It neglects the variation in energy of the emitted beta particle due to self-attenuation, or self-absorption, effects related to the finite size of the sphere. Here it is assumed the sphere is comprised of a pure radioisotope with beta particles being emitted isotropically throughout the material. The full initial possible kinetic energy distribution of a beta particle is taken into account as well as the energy losses due to scattering by other atoms in the microsphere and bremsstrahlung radiation. By combining Longmire's theory of the mean forward range of charged particles and the Rayleigh distribution to take into account the statistical nature of scattering and energy straggling, the linear attenuation, or self-absorption, coefficient for beta-emitting radioisotopes has been deduced. By analogy with gamma radiation transport in spheres, this result was used to calculate the rate of energy emitted by a beta-emitting microsphere and its efficiency. Comparisons to standard point dose kernel formulations generated using Monte Carlo data show the efficacy of the proposed method. Yttrium-90 is used as a specific example throughout, as a medically significant radioisotope, frequently used in radiation therapy for treating cancer.

  2. Experimental investigations of the internal energy of molecules evaporated via laser-induced acoustic desorption into a Fourier transform ion cyclotron resonance mass spectrometer.

    PubMed

    Shea, Ryan C; Petzold, Christopher J; Liu, Ji-Ang; Kenttämaa, Hilkka I

    2007-03-01

    The internal energy of neutral gas-phase organic and biomolecules, evaporated by means of laser-induced acoustic desorption (LIAD) into a Fourier transform ion cyclotron resonance mass spectrometer, was investigated through several experimental approaches. The desorbed molecules were demonstrated not to undergo degradation during the desorption process by collecting LIAD-evaporated molecules and subjecting them to analysis by electrospray ionization/quadrupole ion trap mass spectrometry. Previously established gas-phase basicity values were remeasured for LIAD-evaporated organic molecules and biomolecules with the use of the bracketing method. No endothermic reactions were observed. The remeasured basicity values are in close agreement with the values reported in the literature. The amount of internal energy deposited during LIAD is concluded to be less than a few kilocalories per mole. Chemical ionization with a series of proton-transfer reagents was employed to obtain a breakdown curve for a protonated dipeptide, Val-Pro, evaporated by LIAD. Comparison of this breakdown curve with a previously published analogous curve obtained by using substrate-assisted laser desorption (SALD) to evaporate the peptide suggests that the molecules evaporated via LIAD have a similar internal energy as those evaporated via SALD. PMID:17263513

  3. Acoustic Attraction

    NASA Astrophysics Data System (ADS)

    Oviatt, Eric; Patsiaouris, Konstantinos; Denardo, Bruce

    2009-11-01

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

  4. 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.

  5. 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.

  6. 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.

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

    SciTech Connect

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

    1988-12-01

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

  8. 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?

  9. 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?"

  10. 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 ...

  11. Effects of emitted electron temperature on the plasma sheath

    SciTech Connect

    Sheehan, J. P.; Kaganovich, I. D.; Wang, H.; Raitses, Y.; Sydorenko, D.; Hershkowitz, N.

    2014-06-15

    It has long been known that electron emission from a surface significantly affects the sheath surrounding that surface. Typical fluid theory of a planar sheath with emitted electrons assumes that the plasma electrons follow the Boltzmann relation and the emitted electrons are emitted with zero energy and predicts a potential drop of 1.03T{sub e}/e across the sheath in the floating condition. By considering the modified velocity distribution function caused by plasma electrons lost to the wall and the half-Maxwellian distribution of the emitted electrons, it is shown that ratio of plasma electron temperature to emitted electron temperature significantly affects the sheath potential when the plasma electron temperature is within an order of magnitude of the emitted electron temperature. When the plasma electron temperature equals the emitted electron temperature the emissive sheath potential goes to zero. One dimensional particle-in-cell simulations corroborate the predictions made by this theory. The effects of the addition of a monoenergetic electron beam to the Maxwellian plasma electrons were explored, showing that the emissive sheath potential is close to the beam energy only when the emitted electron flux is less than the beam flux.

  12. Air Coupled Acoustic Thermography (acat) Inspection Technique

    NASA Astrophysics Data System (ADS)

    Zalameda, J. N.; Winfree, W. P.; Yost, W. T.

    2008-02-01

    The scope of this effort is to determine the viability of a new heating technique using a noncontact acoustic excitation source. Because of low coupling between air and the structure, a synchronous detection method is employed. Any reduction in the out of plane stiffness improves the acoustic coupling efficiency and as a result, defective areas have an increase in temperature relative to the surrounding area. Hence a new measurement system, based on air-coupled acoustic energy and synchronous detection is presented. An analytical model of a clamped circular plate is given, experimentally tested, and verified. Repeatability confirms the technique with a measurement uncertainty of +/-6.2 percent. The range of frequencies used was 800-2,000 Hertz. Acoustic excitation and consequent thermal detection of flaws in a helicopter blade is examined and results indicate that air coupled acoustic excitation enables the detection of core damage in sandwich honeycomb structures.

  13. Air Coupled Acoustic Thermography (ACAT) Inspection Technique

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph; Winfree, William P.; Yost, William T.

    2007-01-01

    The scope of this effort is to determine the viability of a new heating technique using a noncontact acoustic excitation source. Because of low coupling between air and the structure, a synchronous detection method is employed. Any reduction in the out of plane stiffness improves the acoustic coupling efficiency and as a result, defective areas have an increase in temperature relative to the surrounding area. Hence a new measurement system, based on air-coupled acoustic energy and synchronous detection is presented. An analytical model of a clamped circular plate is given, experimentally tested, and verified. Repeatability confirms the technique with a measurement uncertainty of plus or minus 6.2 percent. The range of frequencies used was 800-2,000 Hertz. Acoustic excitation and consequent thermal detection of flaws in a helicopter blade is examined and results indicate that air coupled acoustic excitation enables the detection of core damage in sandwich honeycomb structures.

  14. Luminescence and energy-transfer properties of color-tunable Ca2 Mg0.25 Al1.5 Si1.25 O7 :Ce(3+) /Eu(2+) /Tb(3+) phosphors for ultraviolet light-emitting diodes.

    PubMed

    Yuan, Bo; Song, Yanhua; Sheng, Ye; Zheng, Keyan; Huo, Qisheng; Xu, Xuechun; Zou, Haifeng

    2016-03-01

    A series of Ca2 Mg0.25 Al1.5 Si1.25 O7 :Ce(3+) /Eu(2+) /Tb(3+) phosphors was been prepared via a conventional high temperature solid-state reaction and their luminescence properties were studied. The emission spectra of Ca2 Mg0.25 Al1.5 Si1.25 O7 :Ce(3+) ,Eu(2+) and Ca2 Mg0.25 Al1.5 Si1.25 O7 :Ce(3+) ,Tb(3+) phosphors show not only a band due to Ce(3+) ions (409 nm) but also as a band due to Eu(2+) (520 nm) and Tb(3+) (542 nm) ions. More importantly, the effective energy transfer from Ce(3+) to Eu(2+) and Tb(3+) ions was confirmed and investigated by emission/excitation spectra and luminescent decay behaviors. Furthermore, the energy level scheme and energy transfer mechanism were investigated and were demonstrated to be of resonant type via dipole-dipole (Ce(3+) to Eu(2+) ) and dipole-quadrupole (Ce(3+) to Tb(3+) ) reactions, respectively. Under excitation at 350 nm, the emitting color could be changed from blue to green by adjusting the relative doping concentration of Ce(3+) and Eu(2+) ions as well as Ce(3+) and Tb(3+) ions. The above results indicate that Ca2 Mg0.25 Al1.5 Si1.25 O7 :Ce(3+) ,Eu(2+) /Tb(3+) are promising single-phase blue-to-green phosphors for application in phosphor conversion white-light-emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26249728

  15. Envelope Solitons in Acoustically Dispersive Vitreous Silica

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Yost, William T.

    2012-01-01

    Acoustic radiation-induced static strains, displacements, and stresses are manifested as rectified or dc waveforms linked to the energy density of an acoustic wave or vibrational mode via the mode nonlinearity parameter of the material. An analytical model is developed for acoustically dispersive media that predicts the evolution of the energy density of an initial waveform into a series of energy solitons that generates a corresponding series of radiation-induced static strains (envelope solitons). The evolutionary characteristics of the envelope solitons are confirmed experimentally in Suprasil W1 vitreous silica. The value (-11.9 plus or minus 1.43) for the nonlinearity parameter, determined from displacement measurements of the envelope solitons via a capacitive transducer, is in good agreement with the value (-11.6 plus or minus 1.16) obtained independently from acoustic harmonic generation measurements. The agreement provides strong, quantitative evidence for the validity of the model.

  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. Prediction and validation of high frequency vibration repsonses of NASA Mars Pathfinder spacecraft due to acoustic launch load using statistical energy analysis

    NASA Technical Reports Server (NTRS)

    Hwang, H. J.

    2002-01-01

    Mid and high frequency structural responses of a spacecraft during the launch condition are mainly dominated by the intense acoustic pressure field over the exterior of the launch vehicle. The prediction of structural responses due to the acoustic launch load is therefore an important analysis for engineers and scientists to correctly define various dynamics specifications of the spacecraft.

  18. 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.

  19. Acoustic transmitters for underwater neutrino telescopes.

    PubMed

    Ardid, Miguel; Martínez-Mora, Juan A; Bou-Cabo, Manuel; Larosa, Giuseppina; Adrián-Martínez, Silvia; Llorens, Carlos D

    2012-01-01

    In this paper acoustic transmitters that were developed for use in underwater neutrino telescopes are presented. Firstly, an acoustic transceiver has been developed as part of the acoustic positioning system of neutrino telescopes. These infrastructures are not completely rigid and require a positioning system in order to monitor the position of the optical sensors which move due to sea currents. To guarantee a reliable and versatile system, the transceiver has the requirements of reduced cost, low power consumption, high pressure withstanding (up to 500 bars), high intensity for emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring and processing received signals. Secondly, a compact acoustic transmitter array has been developed for the calibration of acoustic neutrino detection systems. The array is able to mimic the signature of ultra-high-energy neutrino interaction in emission directivity and signal shape. The technique of parametric acoustic sources has been used to achieve the proposed aim. The developed compact array has practical features such as easy manageability and operation. The prototype designs and the results of different tests are described. The techniques applied for these two acoustic systems are so powerful and versatile that may be of interest in other marine applications using acoustic transmitters. PMID:22666022

  20. Acoustic Transmitters for Underwater Neutrino Telescopes

    PubMed Central

    Ardid, Miguel; Martínez-Mora, Juan A.; Bou-Cabo, Manuel; Larosa, Giuseppina; Adrián-Martínez, Silvia; Llorens, Carlos D.

    2012-01-01

    In this paper acoustic transmitters that were developed for use in underwater neutrino telescopes are presented. Firstly, an acoustic transceiver has been developed as part of the acoustic positioning system of neutrino telescopes. These infrastructures are not completely rigid and require a positioning system in order to monitor the position of the optical sensors which move due to sea currents. To guarantee a reliable and versatile system, the transceiver has the requirements of reduced cost, low power consumption, high pressure withstanding (up to 500 bars), high intensity for emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring and processing received signals. Secondly, a compact acoustic transmitter array has been developed for the calibration of acoustic neutrino detection systems. The array is able to mimic the signature of ultra-high-energy neutrino interaction in emission directivity and signal shape. The technique of parametric acoustic sources has been used to achieve the proposed aim. The developed compact array has practical features such as easy manageability and operation. The prototype designs and the results of different tests are described. The techniques applied for these two acoustic systems are so powerful and versatile that may be of interest in other marine applications using acoustic transmitters. PMID:22666022

  1. The South Pole Acoustic Test Setup (SPATS)

    NASA Astrophysics Data System (ADS)

    Laihem, Karim; IceCube Collaboration

    2012-11-01

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

  2. Atmospheric Emitted Radiance Interferometer

    DOE Data Explorer

    Gero, Jonathan; Ermold, Brian; Gaustad, Krista; Koontz, Annette; Hackel, Denny; Garcia, Raymond

    2005-01-01

    The atmospheric emitted radiance interferometer (AERI) is a ground-based instrument that measures the downwelling infrared radiance from the Earth’s atmosphere. The observations have broad spectral content and sufficient spectral resolution to discriminate among gaseous emitters (e.g., carbon dioxide and water vapor) and suspended matter (e.g., aerosols, water droplets, and ice crystals). These upward-looking surface observations can be used to obtain vertical profiles of tropospheric temperature and water vapor, as well as measurements of trace gases (e.g., ozone, carbon monoxide, and methane) and downwelling infrared spectral signatures of clouds and aerosols. The AERI is a passive remote sounding instrument, employing a Fourier transform spectrometer operating in the spectral range 3.3–19.2 μm (520–3020 cm-1) at an unapodized resolution of 0.5 cm-1 (max optical path difference of 1 cm). The extended-range AERI (ER-AERI) deployed in dry climates, like in Alaska, have a spectral range of 3.3–25.0 μm (400–3020 cm-1) that allow measurements in the far-infrared region. Typically, the AERI averages views of the sky over a 16-second interval and operates continuously.

  3. Light Emitting Diodes (LEDs)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique, called Photodynamic Therapy, requires the surgeon to use tiny, pinhead-size Light Emitting Diodes (LEDs) (a source that releases long wavelengths of light ) to activate light-sensitive, tumor-treating drugs. 'A young woman operated on in May 1999 has fully recovered with no complications and no evidence of the tumor coming back,' said Dr. Harry Whelan, a pediatric neurologist at the Medical Hospital of Wisconsin in Milwaukee. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can be used for hours at a time while still remaining cool to the touch. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The LEDs, developed and managed by NASA's Marshall Space Flight Center, have been used on seven Space Shuttle flights inside the Microgravity Astroculture Facility. This technology has also been successfully used to further commercial research in crop growth.

  4. Light Emitting Diode (LED)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique called photodynamic therapy, requires the surgeon to use tiny pinhead-size Light Emitting Diodes (LEDs) (a source releasing long wavelengths of light) to activate light-sensitive, tumor-treating drugs. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can also be used for hours at a time while still remaining cool to the touch. The LED probe consists of 144 tiny pinhead-size diodes, is 9-inches long, and about one-half-inch in diameter. The small balloon aids in even distribution of the light source. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The probe was developed for photodynamic cancer therapy by the Marshall Space Flight Center under a NASA Small Business Innovative Research program grant.

  5. Recycling technology of emitted carbon dioxide

    SciTech Connect

    Arakawa, Hironori

    1993-12-31

    Ways to halt global warming are being discussed worldwide. Global warming is an energy problem which is mainly attributed to the large volumes of carbon dioxide (CO{sub 2}) released into the atmosphere from the rapid increase in energy consumption since the Industrial Revolution. The basic solution to the problem, therefore, is to cut consumption of fossil fuels. To this end, it is important to promote energy conservation by improving the fuel efficiency of machines, as well as shift to energy sources that do not emit carbon dioxide and develop related technologies. If current trends in economic growth continue in the devloping world as well as the developed countries, there can be no doubt that energy consumption will increase. Therefore, alongside energy conservation and the development of alternative energies, the importance of technologies to recover and fix CO{sub 2} will increase in the fight against global warming.

  6. 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).

  7. 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

  8. A two-way coupled mode formalism that satisfies energy conservation for impedance boundaries in underwater acoustics.

    PubMed

    Stotts, Steven A; Koch, Robert A

    2015-11-01

    This paper shows that energy conservation and the derivation of the two-way coupled mode range equations can be extended in three dimensions to complex mode functions and eigenvalues. Furthermore, the energy in the coupled mode formulation is conserved for finite thickness fluid ocean waveguides with a penetrable bottom boundary beneath any range dependence. The derivations rely on completeness and a modified orthonormality statement. The mode coupling coefficients are specified solely and explicitly by the waveguide range dependence. The statement of energy conservation is applied to a numerical coupled mode calculation. PMID:26627810

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

    NASA Astrophysics Data System (ADS)

    Mao, Yijun; Xu, Chen; Qi, Datong

    2015-02-01

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

  10. Recent advances in conjugated polymers for light emitting devices.

    PubMed

    Alsalhi, Mohamad Saleh; Alam, Javed; Dass, Lawrence Arockiasamy; Raja, Mohan

    2011-01-01

    A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED) and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs) in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs) and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review. PMID:21673938

  11. Recent Advances in Conjugated Polymers for Light Emitting Devices

    PubMed Central

    AlSalhi, Mohamad Saleh; Alam, Javed; Dass, Lawrence Arockiasamy; Raja, Mohan

    2011-01-01

    A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED) and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs) in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs) and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review. PMID:21673938

  12. Spectra of electrons emitted as a result of the sticking and annihilation of low energy positrons to the surfaces of graphene and highly oriented pyrolytic graphite (HOPG)

    NASA Astrophysics Data System (ADS)

    Chrysler, M.; Chirayath, V.; McDonald, A.; Lim, Z.; Shastry, K.; Gladen, R.; Fairchild, A.; Koymen, A.; Weiss, A.

    Positron annihilation induced Auger electron spectroscopy (PAES) was used to study the positron induced low energy electron spectra from HOPG and a sample composed of 6-8 layers of graphene grown on polycrystalline copper. A low energy (~2eV) beam of positrons was used to implant positrons into a surface localized state on the graphene and HOPG samples. Measurements of the energy spectra of the positron induced electrons obtained using a TOF spectrometer indicate the presence of an annihilation induced KLL C Auger peak (at ~263 eV) along with a narrow low energy secondary peak due to an Auger mediated positron sticking (AMPS) process. A broad spectral feature was also observed below ~15 eV which we believe may be due to a VVV C Auger transition not previously observed. The energy dependence of the integrated intensity of the AMPS peak was measured for a series of incident positron kinetic energies ranging from ~1.5 eV up to 11 eV from which the binding energy of the surface localized positron state on graphene and HOPG was estimated. The implication of our results regarding the applicability of AMPS and PAES to the study of graphene surfaces and interfaces will be discussed. This work was supported by NSF Grant No. DMR 1508719 and DMR 1338130.

  13. MEASUREMENTS OF ABSORPTION, EMISSIVITY REDUCTION, AND LOCAL SUPPRESSION OF SOLAR ACOUSTIC WAVES IN SUNSPOTS

    SciTech Connect

    Chou, D.-Y.; Liang, Z.-C.; Yang, M.-H.; Zhao Hui; Sun, M.-T.

    2009-05-01

    The power of solar acoustic waves in magnetic regions is lower relative to the quiet Sun. Absorption, emissivity reduction, and local suppression of acoustic waves contribute to the observed power reduction in magnetic regions. We propose a model for the energy budget of acoustic waves propagating through a sunspot in terms of the coefficients of absorption, emissivity reduction, and local suppression of the sunspot. Using the property that the waves emitted along the wave path between two points have no correlation with the signal at the starting point, we can separate the effects of these three mechanisms. Applying this method to helioseismic data filtered with direction and phase-velocity filters, we measure the fraction of the contribution of each mechanism to the power deficit in the umbra of the leading sunspot of NOAA 9057. The contribution from absorption is 23.3 {+-} 1.3%, emissivity reduction 8.2 {+-} 1.4%, and local suppression 68.5 {+-} 1.5%, for a wave packet corresponding to a phase velocity of 6.98 x 10{sup -5} rad s{sup -1}.

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

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Anne M.

    2014-01-01

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

  15. Real-time temperature estimation and monitoring of HIFU ablation through a combined modeling and passive acoustic mapping approach

    NASA Astrophysics Data System (ADS)

    Jensen, C. R.; Cleveland, R. O.; Coussios, C. C.

    2013-09-01

    Passive acoustic mapping (PAM) has been recently demonstrated as a method of monitoring focused ultrasound therapy by reconstructing the emissions created by inertially cavitating bubbles (Jensen et al 2012 Radiology 262 252-61). The published method sums energy emitted by cavitation from the focal region within the tissue and uses a threshold to determine when sufficient energy has been delivered for ablation. The present work builds on this approach to provide a high-intensity focused ultrasound (HIFU) treatment monitoring software that displays both real-time temperature maps and a prediction of the ablated tissue region. This is achieved by determining heat deposition from two sources: (i) acoustic absorption of the primary HIFU beam which is calculated via a nonlinear model, and (ii) absorption of energy from bubble acoustic emissions which is estimated from measurements. The two sources of heat are used as inputs to the bioheat equation that gives an estimate of the temperature of the tissue as well as estimates of tissue ablation. The method has been applied to ex vivo ox liver samples and the estimated temperature is compared to the measured temperature and shows good agreement, capturing the effect of cavitation-enhanced heating on temperature evolution. In conclusion, it is demonstrated that by using PAM and predictions of heating it is possible to produce an evolving estimate of cell death during exposure in order to guide treatment for monitoring ablative HIFU therapy. Portions presented at the 13th International Symposium on Therapeutic Ultrasound, Heidelberg, Germany (2012).

  16. The influence of the energy emitted by solar flare soft X-ray bursts on the propagation of their associated interplanetary shock waves

    NASA Technical Reports Server (NTRS)

    Pinter, S.; Dryer, M.

    1985-01-01

    The relationship between the thermal energy released from 29 solar flares and the propagation features of their associated interplanetary shock waves that were detected at 1 AU is investigated. The 29 interplanetary shock waves were identified unambiguously and their tracking from each solar flare was deduced by tracking their associated interplanetary type-II radio emission. The thermal energy released in the solar flares was estimated from the time-intensity profiles of 1-8 A soft X-ray bursts from each flare. A good relationship is found between the flares' thermal energy with the IP shock-waves' transient velocity and arrival time at the earth - that is, the largest flare energy released is associated with the faster shock waves. Finally, a possible scenario of formation of a shock wave during the early phase of the flare and its propagation features is discussed.

  17. The lowest-energy chlorophyll of photosystem II is adjacent to the peripheral antenna: Emitting states of CP47 assigned via circularly polarized luminescence.

    PubMed

    Hall, Jeremy; Renger, Thomas; Müh, Frank; Picorel, Rafael; Krausz, Elmars

    2016-09-01

    The identification of low-energy chlorophyll pigments in photosystem II (PSII) is critical to our understanding of the kinetics and mechanism of this important enzyme. We report parallel circular dichroism (CD) and circularly polarized luminescence (CPL) measurements at liquid helium temperatures of the proximal antenna protein CP47. This assembly hosts the lowest-energy chlorophylls in PSII, responsible for the well-known "F695" fluorescence band of thylakoids and PSII core complexes. Our new spectra enable a clear identification of the lowest-energy exciton state of CP47. This state exhibits a small but measurable excitonic delocalization, as predicated by its CD and CPL. Using structure-based simulations incorporating the new spectra, we propose a revised set of site energies for the 16 chlorophylls of CP47. The significant difference from previous analyses is that the lowest-energy pigment is assigned as Chl 612 (alternately numbered Chl 11). The new assignment is readily reconciled with the large number of experimental observations in the literature, while the most common previous assignment for the lowest energy pigment, Chl 627(29), is shown to be inconsistent with CD and CPL results. Chl 612(11) is near the peripheral light-harvesting system in higher plants, in a lumen-exposed region of the thylakoid membrane. The low-energy pigment is also near a recently proposed binding site of the PsbS protein. This result consequently has significant implications for our understanding of the kinetics and regulation of energy transfer in PSII. PMID:27342201

  18. Investigation of Förster-type energy transfer in organic light-emitting devices with 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethy ljulolidin-4-yl-vinyl)-4H-pyran doped cohost emitting layer

    NASA Astrophysics Data System (ADS)

    Yu, Li-Zhen; Jiang, Xue-Yin; Zhang, Zhi-Lin; Lou, Li-Ren; Lee, Ching-Ting

    2009-01-01

    Organic light-emitting devices (OLEDs) with cohosted emitter, which is composed of 9,10-di(2-naphthyl)anthracene (ADN) and tris(8-hydroxy-quinolinato) aluminum (Alq3) and doped with 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethy ljulolidin-4-yl-vinyl)-4H-pyran (DCJTB), were fabricated and studied. The efficiency of OLEDs with a cohost emitter was higher than that with a single host emitter. For the cohost emitter with ADN/Alq3 weight ratio of 75:25, the 3.4 cd/A efficiency of the resulted OLEDs was obtained. It is found that the absorption spectra of DCJTB and the emission spectra of Alq3 changed with the composition of the emitter. This phenomenon is attributed to the polarization effect. On the basis of the Förster's theory, the resulted overlap integral exhibits the highest value for this cohost emitter. The experimental results reveal that the cascade energy transfer plays an important role in the luminance efficiency enhancement of the cohost emitter in OLEDs.

  19. Targeted energy transfers and passive acoustic wave redirection in a two-dimensional granular network under periodic excitation

    SciTech Connect

    Zhang, Yijing Moore, Keegan J.; Vakakis, Alexander F.; McFarland, D. Michael

    2015-12-21

    We study passive pulse redirection and nonlinear targeted energy transfer in a granular network composed of two semi-infinite, ordered homogeneous granular chains mounted on linear elastic foundations and coupled by weak linear stiffnesses. Periodic excitation in the form of repetitive half-sine pulses is applied to one of the chains, designated as the “excited chain,” whereas the other chain is initially at rest and is regarded as the “absorbing chain.” We show that passive pulse redirection and targeted energy transfer from the excited to the absorbing chain can be achieved by macro-scale realization of the spatial analog of the Landau-Zener quantum tunneling effect. This is realized by finite stratification of the elastic foundation of the excited chain and depends on the system parameters (e.g., the percentage of stratification) and on the parameters of the periodic excitation. Utilizing empirical mode decomposition and numerical Hilbert transforms, we detect the existence of two distinct nonlinear phenomena in the periodically forced network; namely, (i) energy localization in the absorbing chain due to sustained 1:1 resonance capture leading to irreversible pulse redirection from the excited chain, and (ii) continuous energy exchanges in the form of nonlinear beats between the two chains in the absence of resonance capture. Our results extend previous findings of transient passive energy redirection in impulsively excited granular networks and demonstrate that steady state passive pulse redirection in these networks can be robustly achieved under periodic excitation.

  20. Targeted energy transfers and passive acoustic wave redirection in a two-dimensional granular network under periodic excitation

    NASA Astrophysics Data System (ADS)

    Zhang, Yijing; Moore, Keegan J.; McFarland, D. Michael; Vakakis, Alexander F.

    2015-12-01

    We study passive pulse redirection and nonlinear targeted energy transfer in a granular network composed of two semi-infinite, ordered homogeneous granular chains mounted on linear elastic foundations and coupled by weak linear stiffnesses. Periodic excitation in the form of repetitive half-sine pulses is applied to one of the chains, designated as the "excited chain," whereas the other chain is initially at rest and is regarded as the "absorbing chain." We show that passive pulse redirection and targeted energy transfer from the excited to the absorbing chain can be achieved by macro-scale realization of the spatial analog of the Landau-Zener quantum tunneling effect. This is realized by finite stratification of the elastic foundation of the excited chain and depends on the system parameters (e.g., the percentage of stratification) and on the parameters of the periodic excitation. Utilizing empirical mode decomposition and numerical Hilbert transforms, we detect the existence of two distinct nonlinear phenomena in the periodically forced network; namely, (i) energy localization in the absorbing chain due to sustained 1:1 resonance capture leading to irreversible pulse redirection from the excited chain, and (ii) continuous energy exchanges in the form of nonlinear beats between the two chains in the absence of resonance capture. Our results extend previous findings of transient passive energy redirection in impulsively excited granular networks and demonstrate that steady state passive pulse redirection in these networks can be robustly achieved under periodic excitation.

  1. Auger Emitting Radiopharmaceuticals for Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Falzone, Nadia; Cornelissen, Bart; Vallis, Katherine A.

    Radionuclides that emit Auger electrons have been of particular interest as therapeutic agents. This is primarily due to the short range in tissue, controlled linear paths and high linear energy transfer of these particles. Taking into consideration that ionizations are clustered within several cubic nanometers around the point of decay the possibility of incorporating an Auger emitter in close proximity to the cancer cell DNA has immense therapeutic potential thus making nuclear targeted Auger-electron emitters ideal for precise targeting of cancer cells. Furthermore, many Auger-electron emitters also emit γ-radiation, this property makes Auger emitting radionuclides a very attractive option as therapeutic and diagnostic agents in the molecular imaging and management of tumors. The first requirement for the delivery of Auger emitting nuclides is the definition of suitable tumor-selective delivery vehicles to avoid normal tissue toxicity. One of the main challenges of targeted radionuclide therapy remains in matching the physical and chemical characteristics of the radionuclide and targeting moiety with the clinical character of the tumor. Molecules and molecular targets that have been used in the past can be classified according to the carrier molecule used to deliver the Auger-electron-emitting radionuclide. These include (1) antibodies, (2) peptides, (3) small molecules, (4) oligonucleotides and peptide nucleic acids (PNAs), (5) proteins, and (6) nanoparticles. The efficacy of targeted radionuclide therapy depends greatly on the ability to increase intranuclear incorporation of the radiopharmaceutical without compromising toxicity. Several strategies to achieve this goal have been proposed in literature. The possibility of transferring tumor therapy based on the emission of Auger electrons from experimental models to patients has vast therapeutic potential, and remains a field of intense research.

  2. Advanced Technology Development for Active Acoustic Liners

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  3. Acoustic simulation in architecture with parallel algorithm

    NASA Astrophysics Data System (ADS)

    Li, Xiaohong; Zhang, Xinrong; Li, Dan

    2004-03-01

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

  4. 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.

  5. 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.

  6. Optimizing thermoacoustic regenerators for maximum amplification of acoustic power.

    PubMed

    Holzinger, Tobias; Emmert, Thomas; Polifke, Wolfgang

    2014-11-01

    Identifying optimum design parameters and operating conditions of thermoacoustic engines or refrigerators is crucial for the further development of such devices. This publication proposes an optimization criterion for the stack of a thermoacoustic device with the objective of maximizing the amplification of acoustic energy by the stack. For this purpose, the stack is described as an acoustic multi-port, represented mathematically by its scattering matrix. It is shown how the scattering matrix may be deduced from the standard thermo-acoustic governing equations. Then an acoustic power balance is deduced from the scattering matrix. The spectral norm and the eigenvectors of the scattering matrix identify optimal acoustic states. Stack design operating parameters and frequencies with maximum amplification of acoustic power are identified for various stack configurations. The corresponding acoustic states are interpreted physically. PMID:25373945

  7. Refraction of acoustic duct waveguide modes by exhaust jets.

    NASA Technical Reports Server (NTRS)

    Mani, R.

    1973-01-01

    The refraction of acoustic duct waveguide modes emitted from the open end of a semiinfinite rectangular duct by a jet-like exhaust flow is studied theoretically. The problem is formulated as a Wiener-Hopf problem and is ultimately solved by an approximate method due to Carrier and Koiter. Continuity of transverse acoustic particle displacement and of acoustic pressure is assumed at the jet/still-air interface. The solution exhibits several features of the acoustics of moving media such as a source convection effect, zones of relative silence, and simple refraction. Plots of far-field directivity patterns are presented for several cases and show refraction effects to be important even at modest exhaust Mach numbers of order 0.3. Only subsonic exhaust Mach numbers are considered.

  8. 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.

  9. 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.

  10. Physiological Acoustics

    NASA Astrophysics Data System (ADS)

    Young, Eric D.

    The analysis of physiological sound in the peripheral auditory system solves three important problems. First, sound energy impinging on the head must be captured and presented to the transduction apparatus in the ear as a suitable mechanical signal; second, this mechanical signal needs to be transduced into a neural representation that can be used by the brain; third, the resulting neural representation needs to be analyzed by central neurons to extract information useful to the animal. This chapter provides an overview of some aspects of the first two of these processes. The description is entirely focused on the mammalian auditory system, primarily on human hearing and on the hearing of a few commonly used laboratory animals (mainly rodents and carnivores). Useful summaries of non-mammalian hearing are available [1]. Because of the large size of the literature, review papers are referenced wherever possible.

  11. Time dependent formulation of the energy loss by an accelerated intense electron beam just emitted by the cathode of RF-FEL photoinjector

    NASA Astrophysics Data System (ADS)

    Salah, Wa'el; Coacolo, J.-L.; Hallak, A. B.; Al-Obaid, M.

    2006-08-01

    The energy loss by an accelerated electron bunch of a conical shape propagating in the laser-driven RF-photoinjector is expressed in terms of an expansion of the vector and scalar potentials into a series of eigenfunctions of the empty unit "pill-box" cavity. A versatile and simple analytical formula which can be easily applied to a bunch of any shape is obtained.

  12. Material fabrication using acoustic radiation forces

    SciTech Connect

    Sinha, Naveen N.; Sinha, Dipen N.; Goddard, Gregory Russ

    2015-12-01

    Apparatus and methods for using acoustic radiation forces to order particles suspended in a host liquid are described. The particles may range in size from nanometers to millimeters, and may have any shape. The suspension is placed in an acoustic resonator cavity, and acoustical energy is supplied thereto using acoustic transducers. The resulting pattern may be fixed by using a solidifiable host liquid, forming thereby a solid material. Patterns may be quickly generated; typical times ranging from a few seconds to a few minutes. In a one-dimensional arrangement, parallel layers of particles are formed. With two and three dimensional transducer arrangements, more complex particle configurations are possible since different standing-wave patterns may be generated in the resonator. Fabrication of periodic structures, such as metamaterials, having periods tunable by varying the frequency of the acoustic waves, on surfaces or in bulk volume using acoustic radiation forces, provides great flexibility in the creation of new materials. Periodicities may range from millimeters to sub-micron distances, covering a large portion of the range for optical and acoustical metamaterials.

  13. Wavelet Analysis for Acoustic Phased Array

    NASA Astrophysics Data System (ADS)

    Kozlov, Inna; Zlotnick, Zvi

    2003-03-01

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

  14. In-Flight Rotorcraft Acoustics Program

    NASA Technical Reports Server (NTRS)

    Peterson, Randall L.; Warmbrodt, William (Technical Monitor)

    1996-01-01

    A key part of NASA's aeronautics research is reducing noise to make helicopters and tiltrotors more acceptable to the public. The objective of the In-Flight Rotorcraft Acoustics Program (IRAP) is to acquire rotorcraft. noise data in flight for comparison to wind tunnel data. The type of noise of concern is "blade-vortex-interaction," or BVI, noise. Microphones on the wing tips and tail fin of the quiet NASA YO-3A Acoustics Research Aircraft measure BVI noise while the YO-3A descends in close formation with the helicopter or tiltrotor emitting the noise.The data acquired through IRAP is needed to validate wind-tunnel test results, or, where the results cannot be validated, to provide researchers with clues as to how to improve testing methods.

  15. The feedback phenomenon applied to underwater acoustics

    NASA Astrophysics Data System (ADS)

    Roux, Philippe; Jordan, Jason E.; Kuperman, W. A.

    2002-11-01

    People are familiar with the feedback phenomenon that results in the loud sound heard when a musician plays an electric instrument directly into a speaker. Feedback occurs when a source and a receiver are connected both acoustically through the propagation medium and electrically through an amplifier in such way that the received signal is simultaneously and continuously added to the emitted signal. A resonance is then obtained when the emitter and the receiver are in phase. The resonant frequency appears to be highly sensitive to fluctuations of the propagation medium. The feedback phenomenon has been experimentally demonstrated as a means to monitor the temperature fluctuation of a shallow water environment [''Acoustic monitoring of the sea medium variability: experimental testing of new methods,'' by A. V. Furduev, Acoust. Phys. 47, No. 3, 361-368 (2001)]. The goal of our work is to reproduce the feedback experiment using an alternative method that decomposes the feedback phenomenon into an iterative process. Successful reproduction of the feedback is accomplished using a step-by-step algorithm which details the evolution of the system from the initial signal to its steady-state form. These experimental and numerical results illustrate the potential of the feedback process for use in narrow-band acoustical tomography.

  16. Digital signal processing in acoustics. I

    NASA Astrophysics Data System (ADS)

    Davies, H.; McNeil, D. J.

    1985-11-01

    Digital signal processing techniques have gained steadily in importance over the past few years in many areas of science and engineering and have transformed the character of instrumentation used in laboratory and plant. This is particularly marked in acoustics, which has both benefited from the developments in signal processing and provided significant stimulus for these developments. As a result acoustical techniques are now used in a very wide range of applications and acoustics is one area in which digital signal processing is exploited to its limits. For example, the development of fast algorithms for computing Fourier transforms and the associated developments in hardware have led to remarkable advances in the use of spectral analysis as a means of investigating the nature and characteristics of acoustic sources. Speech research has benefited considerably in this respect, and, in a rather more technological application, spectral analysis of machinery noise provides information about changes in machine condition which may indicate imminent failure. More recently the observation that human and animal muscles emit low intensity noise suggests that spectral analysis of this noise may yield information about muscle structure and performance.

  17. Resonant interaction of acoustic waves with subaqueous bedforms: Sand dunes in the South China Sea.

    PubMed

    Chiu, Linus Y S; Chang, Andrea Y Y; Reeder, D Benjamin

    2015-12-01

    The large subaqueous sand dunes in the South China Sea are expected to produce the coupling of energy between acoustic normal modes. In this letter, resonant interaction between acoustic propagating modes and subaqueous bedforms are numerically investigated as a function of bedform wavelength, acoustic frequency and bedform packet length. The results demonstrate that bedform wavelength impacts acoustic mode coupling behavior, with the principal transfer of energy occurring between acoustic modes whose eigenvalue difference is equal to the peak value in the bedform wavenumber spectrum. The observed effect of wavelength is greater than that of acoustic frequency and bedform packet length. PMID:26723360

  18. 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.

  19. 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.

  20. 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.

  1. Acoustic microscope surface inspection system and method

    DOEpatents

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

    1991-01-01

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

  2. Acoustic microscope surface inspection system and method

    DOEpatents

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

    1991-02-26

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

  3. Luminescent properties and energy transfer of double-emitting Na2SrMgP2O8:Eu2+, Mn2+ phosphor

    NASA Astrophysics Data System (ADS)

    Wanjun, Tang; Shanshan, Hu; Fen, Zhang

    2013-10-01

    Olgite-type Na2SrMgP2O8 doped with Eu2+ and Mn2+ solely or doubly were prepared by a combustion-assisted synthesis method. The phase formation was confirmed by X-ray powder diffraction measurement. Upon excitation of 352 nm ultraviolet (UV) light, two intense broad bands have clearly been observed due to the allowed 5d-4f transition of Eu2+ and the forbidden 4T1-6A1 transition of Mn2+, respectively. On the basis of the luminescence spectra and fluorescence decay curves, we confirm that the energy transfer process from the Eu2+ to Mn2+ ions occur in the codoped Na2SrMgP2O8:Eu2+, Mn2+ phosphor. The composition-optimized Na2Sr0.99MgP2O8:0.01Eu2+ and Na2Sr0.99Mg0.9P2O8: 0.01Eu2+, 0.1Mn2+ phosphors exhibits superior external quantum efficiency (87.2% and 69.3%, respectively). Based on the principle of energy transfer, the relative intensities of blue and red emission could be tuned by adjusting the contents of Eu2+ and Mn2+.

  4. A single-component white-emitting CaSr2Al2O6:Ce3+, Li+, Mn2+ phosphor via energy transfer.

    PubMed

    Li, Yanyan; Shi, Yurong; Zhu, Ge; Wu, Quansheng; Li, Hao; Wang, Xicheng; Wang, Qian; Wang, Yuhua

    2014-07-21

    A series of single-component Ce(3+), Li(+), Mn(2+) ions codoped color-tunable CaSr2Al2O6 phosphors were synthesized by a high-temperature solid-state reaction, and the photoluminescence properties as well as the energy transfer mechanism from Ce(3+) to Mn(2+) ions have been investigated in detail. The Ce(3+) activated phosphors have strong absorption in the range of 250-420 nm and can give a blue emission centered at about 460 nm. When Mn(2+) ions are codoped, the emission of CaSr2Al2O6:Ce(3+), Li(+), Mn(2+) phosphors can be tuned from blue to red through adjusting the doping concentration of the Mn(2+) ions, under the irradiation of 358 nm. When the concentration of Mn(2+) is increased to 0.02, a warm-white light can be obtained with good CIE coordinates of (0.388, 0.323) and a low CCT of 3284 K. The energy transfer mechanism from the Ce(3+) to Mn(2+) ions is demonstrated to be a quadrupole-quadrupole interaction based on the analysis of the decay curves of the phosphors. The thermal quenching stability was also investigated. The results indicate that CaSr2Al2O6:Ce(3+), Li(+), Mn(2+) samples might have potential applications in w-LEDs. PMID:24968122

  5. Manipulating Liquids With Acoustic Radiation Pressure Phased Arrays

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C.

    1999-01-01

    High-intensity ultrasound waves can produce the effects of "Acoustic Radiation Pressure" (ARP) and "acoustic streaming." These effects can be used to propel liquid flows and to apply forces that can be used to move or manipulate floating objects or liquid surfaces. NASA's interest in ARP includes the remote-control agitation of liquids and the manipulation of bubbles and drops in liquid experiments and propellant systems. A high level of flexibility is attained by using a high-power acoustic phased array to generate, steer, and focus a beam of acoustic waves. This is called an Acoustic Radiation Pressure Phased Array, or ARPPA. In this approach, many acoustic transducer elements emit wavelets that converge into a single beam of sound waves. Electronically coordinating the timing, or "phase shift," of the acoustic waves makes it possible to form a beam with a predefined direction and focus. Therefore, a user can direct the ARP force at almost any desired point within a liquid volume. ARPPA lets experimenters manipulate objects anywhere in a test volume. This flexibility allow it to be used for multiple purposes, such as to agitate liquids, deploy and manipulate drops or bubbles, and even suppress sloshing in spacecraft propellant tanks.

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. Visualizing underwater acoustic matched-field processing

    NASA Astrophysics Data System (ADS)

    Rosenblum, Lawrence; Kamgar-Parsi, Behzad; Karahalios, Margarida; Heitmeyer, Richard

    1991-06-01

    Matched-field processing is a new technique for processing ocean acoustic data measured by an array of hydrophones. It produces estimates of the location of sources of acoustic energy. This method differs from source localization techniques in other disciplines in that it uses the complex underwater acoustic environment to improve the accuracy of the source localization. An unexplored problem in matched-field processing has been to separate multiple sources within a matched-field ambiguity function. Underwater acoustic processing is one of many disciplines where a synthesis of computer graphics and image processing is producing new insight. The benefits of different volume visualization algorithms for matched-field display are discussed. The authors show how this led to a template matching scheme for identifying a source within the matched-field ambiguity function that can help move toward an automated source localization process.

  12. Review of Combustion-acoustic Instabilities

    NASA Technical Reports Server (NTRS)

    Oyediran, Ayo; Darling, Douglas; Radhakrishnan, Krishnan

    1995-01-01

    Combustion-acoustic instabilities occur when the acoustic energy increase due to the unsteady heat release of the flame is greater than the losses of acoustic energy from the system. The problem of combustion-acoustic instability is a concern in many devices for various reasons, as each device may have a unique mechanism causing unsteady heat release rates and many have unique boundary conditions. To accurately predict and quantify combustion-acoustic stabilities, the unsteady heat release rate and boundary conditions need to be accurately determined. The present review brings together work performed on a variety of practical combustion devices. Many theoretical and experimental investigations of the unsteady heat release rate have been performed, some based on perturbations in the fuel delivery system particularly for rocket instabilities, while others are based on hydrodynamic processes as in ramjet dump combustors. The boundary conditions for rocket engines have been analyzed and measured extensively. However, less work has been done to measure acoustic boundary conditions in many other combustion systems.

  13. Apparatus for acoustically coupling an ultrasonic transducer with a body

    NASA Technical Reports Server (NTRS)

    Marshall, Scot H. (Inventor)

    1993-01-01

    An apparatus for acoustically coupling an ultrasonic transducer with a body along whose surface waves are to be transmitted includes a wedge having a first surface for acoustically contacting a subject surface area of a body to be measured, on which surface waves are to be transmitted, and a second surface for accoustically contacting an ultrasonic transducer. The wedge includes a cylinder in which the second surface is present and which is movably disposed in a recess in a block in which the first surface is present, for orienting the first surface and the second surface relative to each other so that ultrasonic waves emitted by the ultrasonic transducer generate surface waves which travel on the subject surface area of the body when the ultrasonic transducer is in acoustic contact with the second surface and the first surface is in acoustic contact with the subject surface area of the body. In the preferred embodiment, there is a third surface which is orientable relative to the first surface so that ultrasonic waves emitted by an ultrasonic transducer in contact with the third surface generate surface waves which travel on the subject surface area of the body when the first surface is an acoustic contact with the subject surface area of the body.

  14. Energy deficit of pulsed-laser field-ionized and field-emitted ions from non-metallic nano-tips

    SciTech Connect

    Arnoldi, L.; Silaeva, E. P.; Gaillard, A.; Vurpillot, F.; Blum, I.; Rigutti, L.; Deconihout, B.; Vella, A.

    2014-05-28

    The energy deficit of pulsed-laser field-evaporated ions and field-ionized atoms of an inert gas from the surface of a non-metallic nano-metric tip is reported as a function of the laser intensity, ion current, and temperature. A new model is proposed to explain these results, taking into account the resistive properties of non-metallic nano-tips. A good agreement between the theoretical predictions and the experimental results is obtained for all parameters investigated experimentally. This model is also used to discuss the evaporation behavior of oxides analyzed in laser-assisted atom probe tomography. New insight into the contribution of the electrostatic field and the laser illumination on the evaporation process of non-metallic materials is given.

  15. Progressive Shear Failure in Granular Materials: Linking Force Fluctuations With Acoustic Emissions

    NASA Astrophysics Data System (ADS)

    Michlmayr, G. K.; Cohen, D. O.; Or, D.

    2011-12-01

    Natural hazards associated with rapid mass movements such as shallow landslides, rock falls or debris flows are notoriously difficult to predict even though precursor events associated with small internal failures are known to occur. In this study we focus on grain scale processes preceding the formation of a shear plane in granular materials such as frictional sliding of grain contacts, accommodation of contact networks and fracturing of grain bonds (in cohesive materials) - all of which are discrete micro-mechanical failure events that emit characteristic acoustic emissions that could be used to study internal failure and potentially provide early warning (albeit short). Experiments involving direct shear tests using glass beads and sand were combined with acoustic emission (AE) measurements using piezoelectric sensors with sensitivities to frequencies in the range of 20kHz - 200kHz and accelerometers (0.2kHz - 20kHz) buried within the sheared sample. We obtained good correlations between shear deformation and associated grain-scale mechanical behavior with key characteristics of measured AE (frequency content, signal energy). Fluctuations of shear force occurring during strain controlled deformation are assumed to represent micro-structural rearrangements of the material. We obtained exponential distributions of force fluctuation magnitudes and low frequency AE event statistics. The number of AE events increased with confining stress as well as with particle roughness and were inversely related to grain size. These results were linked with conceptual models of failure accumulation such as the fiber-bundle model. The statistics of AE event occurrence, particularly magnitude-frequency distributions may provide prediction of imminent mechanical collapse. The strong attenuation of acoustic signals within most earth materials present a major challenge to field applications requiring innovative deployment strategies such as the use of acoustic waveguides.

  16. Acoustic Communication at the Water's Edge: Evolutionary Insights from a Mudskipper

    PubMed Central

    Polgar, Gianluca; Malavasi, Stefano; Cipolato, Giacomo; Georgalas, Vyron; Clack, Jennifer A.; Torricelli, Patrizia

    2011-01-01

    Coupled behavioural observations and acoustical recordings of aggressive dyadic contests showed that the mudskipper Periophthalmodon septemradiatus communicates acoustically while out of water. An analysis of intraspecific variability showed that specific acoustic components may act as tags for individual recognition, further supporting the sounds' communicative value. A correlative analysis amongst acoustical properties and video-acoustical recordings in slow-motion supported first hypotheses on the emission mechanism. Acoustic transmission through the wet exposed substrate was also discussed. These observations were used to support an “exaptation hypothesis”, i.e. the maintenance of key adaptations during the first stages of water-to-land vertebrate eco-evolutionary transitions (based on eco-evolutionary and palaeontological considerations), through a comparative bioacoustic analysis of aquatic and semiterrestrial gobiid taxa. In fact, a remarkable similarity was found between mudskipper vocalisations and those emitted by gobioids and other soniferous benthonic fishes. PMID:21738663

  17. Laser and acoustic lens for lithotripsy

    DOEpatents

    Visuri, Steven R.; Makarewicz, Anthony J.; London, Richard A.; Benett, William J.; Krulevitch, Peter; Da Silva, Luiz B.

    2002-01-01

    An acoustic focusing device whose acoustic waves are generated by laser radiation through an optical fiber. The acoustic energy is capable of efficient destruction of renal and biliary calculi and deliverable to the site of the calculi via an endoscopic procedure. The device includes a transducer tip attached to the distal end of an optical fiber through which laser energy is directed. The transducer tip encapsulates an exogenous absorbing dye. Under proper irradiation conditions (high absorbed energy density, short pulse duration) a stress wave is produced via thermoelastic expansion of the absorber for the destruction of the calculi. The transducer tip can be configured into an acoustic lens such that the transmitted acoustic wave is shaped or focused. Also, compressive stress waves can be reflected off a high density/low density interface to invert the compressive wave into a tensile stress wave, and tensile stresses may be more effective in some instances in disrupting material as most materials are weaker in tension than compression. Estimations indicate that stress amplitudes provided by this device can be magnified more than 100 times, greatly improving the efficiency of optical energy for targeted material destruction.

  18. 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.

  19. Tunable blue-green-emitting Ba3LaNa(PO4)3F:Eu2+,Tb3+ phosphor with energy transfer for near-UV white LEDs.

    PubMed

    Jiao, Mengmeng; Guo, Ning; Lü, Wei; Jia, Yongchao; Lv, Wenzhen; Zhao, Qi; Shao, Baiqi; You, Hongpeng

    2013-09-16

    A series of Eu(2+) and Eu(2+)/Tb(3+) activated novel Ba3LaNa(PO4)3F phosphors have been synthesized by traditional solid state reaction. Rietveld structure refinement of the obtained phosphor indicates that the Ba3LaNa(PO4)3F host contains three kinds of Ba sites. The photoluminescence properties exhibit that the obtained phosphors can be efficiently excited in the range from 320 to 430 nm, which matches perfectly with the commercial n-UV LED chips. The critical distance of the Eu(2+) ions in Ba3LaNa(PO4)3F:Eu(2+) is calculated and the energy quenching mechanism is proven to be dipole-dipole interaction. Tunable blue-green emitting Ba3LaNa(PO4)3F:Eu(2+),Tb(3+) phosphor has been obtained by co-doping Eu(2+) and Tb(3+) ions into the host and varying their relative ratios. Compared with the Tb(3+) singly doped phosphor, the codoped phosphors have more intense absorption in the n-UV range and stronger emission of the Tb(3+) ions, which are attributed to the effective energy transfer from the Eu(2+) to Tb(3+) ions. The energy transfer from the Eu(2+) to Tb(3+) ions is demonstrated to be a dipole-quadrupole mechanism by the Inokuti-Hirayama (I-H) model. The Eu(2+) and Tb(3+) activated phosphor may be good candidates for blue-green components in n-UV white LEDs. PMID:23992135

  20. The acoustic field in the ionosphere caused by an underground nuclear explosion

    NASA Astrophysics Data System (ADS)

    Krasnov, V. M.; Drobzheva, Ya. V.

    2005-07-01

    The problem of describing the generation and propagation of an infrasonic wave emitted by a finite extended source in the inhomogeneous absorbing atmosphere is the focus of this paper. It is of interest since the role of infrasonic waves in the energy balance of the upper atmosphere remains largely unknown. We present an algorithm, which allows adaptation of a point source model for calculating the infrasonic field from an underground nuclear explosion at ionospheric altitudes. Our calculations appear to agree remarkably well with HF Doppler sounding data measured for underground nuclear explosions at the Semipalatinsk Test Site. We show that the temperature and ionospheric electron density perturbation caused by an acoustic wave from underground nuclear explosion can reach 10% of background levels.

  1. U.S. Department of Energy, National Energy Technology Laboratory Solid-State Lighting Core Technologies Light Emitting Diodes on Semipolar Bulk GaN Substrate with IQE > 80% at 150 A/cm2 and 100 0C

    SciTech Connect

    Chakraborty, Arpan; David, Aurelien; Grundmann, Michael; Tyagi, Anurag; Craven, Michael; Hurni, Christophe; Cich, Michael

    2015-03-31

    GaN is a crucial material for light-emitting diodes (LEDs) emitting in the violet-to-green range. Despite its good performance, it still suffers from significant technical limitations. In particular, the efficiency of GaN-based LEDs decreases at high current (“current droop”) and high temperature (“temperature droop”). This is problematic in some lighting applications, where a high-power operation is required. This program studied the use of particular substrates to improve the efficiency of GaN-based LEDs: bulk semipolar (SP) GaN substrates. These substrates possess a very high material quality, and physical properties which are distinctly different from legacy substrates currently used in the LED industry. The program focused on the development of accurate metrology to quantify the performance of GaN-based LEDs, and on improvement to LED quality and design on SP substrates. Through a thorough optimization process, we demonstrated violet LEDs with very high internal quantum efficiency, exceeding 85% at high temperature and high current. We also investigated longer-wavelength blue emitters, but found that the limited strain budget was a key limitation.

  2. The acoustic role of tracheal chambers and nasal cavities in the production of sonar pulses by the horseshoe bat, Rhinolophus hildebrandti.

    PubMed

    Suthers, R A; Hartley, D J; Wenstrup, J J

    1988-04-01

    The acoustic role of the enlarged, bony, nasal cavities and rigid tracheal chambers in the horseshoe bat, Rhinolophus hildebrandti (Fig. 2) was investigated by determining the effect of their selective filling on the nasally emitted sonar pulse and on the sound traveling backwards down the trachea. Normal sonar signals of this bat contain a long constant frequency component with most energy in the second harmonic at about 48 kHz. The fundamental is typically suppressed 20 to 30 dB below the level of the second harmonic (Fig. 1). None of the experimental manipulations described affected the frequency of the sonar signal fundamental. Filling the dorsal and both lateral tracheal chambers had little effect on the emitted vocalization, but caused the level of the fundamental component in the trachea to increase 15 to 19 dB in most bats (Table 2). When only the dorsal chamber or only the two lateral chambers were filled, the effect was less striking and more variable (Tables 3 and 4), suggesting that the tracheal fundamental is normally suppressed by acoustic interaction between these three cavities. Filling the enlarged dorsal nasal cavities had no effect on the tracheal sound. The effect of this treatment on the nasally emitted sonar pulse was inconsistent. Sometimes the fundamental increased 10 to 12 dB, other times the intensity of all harmonics decreased; in still other cases the second, third or fourth harmonic increased, but the fundamental remained unchanged (Tables 5, 6, and 7). When bats were forced to vocalize through the mouth, by sealing the nostrils, there was a prominent increase in the level of the emitted fundamental (10 to 21 dB) and in the fourth harmonic (6 to 17 dB). In one instance there was also a significant increase in the level of the third harmonic (Tables 8 and 9). The supraglottal tract thus filters the fundamental from the nasally emitted sonar signal, although the role of the inflated nasal cavities in this process is unclear. We conclude

  3. 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.

  4. 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.

  5. Blue light emitting thiogallate phosphor

    DOEpatents

    Dye, Robert C.; Smith, David C.; King, Christopher N.; Tuenge, Richard T.

    1998-01-01

    A crystalline blue emitting thiogallate phosphor of the formula RGa.sub.2 S.sub.4 :Ce.sub.x where R is selected from the group consisting of calcium, strontium, barium and zinc, and x is from about 1 to 10 atomic percent, the phosphor characterized as having a crystalline microstructure on the size order of from about 100 .ANG. to about 10,000 .ANG. is provided together with a process of preparing a crystalline blue emitting thiogallate phosphor by depositing on a substrate by CVD and resultant thin film electroluminescent devices including a layer of such deposited phosphor on an ordinary glass substrate.

  6. Influence of Al3+doping on the energy levels and thermal property of the 3.5MgO·0.5MgF2·GeO2:Mn4+ red-emitting phosphor

    NASA Astrophysics Data System (ADS)

    Yuan, Lin-lin; Zhang, Xiao-Song; Xu, Jian-Ping; Sun, Jian; Jin, Han; Liu, Xiao-Juan; Li, Lin-Lin; Li, Lan

    2015-08-01

    A series of Al3+ -doped 3.5MgO·0.5MgF2·GeO2:Mn4+ red-emitting phosphors is synthesized by high temperature solid-state reaction. The broad excitation band at 300 nm-380 nm, resulting from the 4A2 → 4T1 transition of Mn4+, exhibits a blue shift with the increase of Al2O3 content. The observation of the decreased Mn4+O2 - distance is explained by the crystal field theory. The temperature-dependent photoluminescence spectra with various amounts of Al2O3 content are comparatively measured and the calculation shows that the activation energy increases up to 0.41 eV at the Al2O3 content of 0.1 mol. The maximum phonon densities of state for these samples are calculated from Raman spectra and they are correlated with the thermal properties. Project supported by the National High Technology Research and Development Program of China (Grant No. 2013AA014201), the Natural Science Foundation of Tianjin City, China (Grant Nos. 11JCYBJC00300 and 14JCZDJC31200), and the National Key Foundation for Exploring Scientific Instrument of China (Grant No. 2014YQ120351).

  7. 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

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. White organic light-emitting diodes with ultra-thin mixed emitting layer

    NASA Astrophysics Data System (ADS)

    Jeon, T.; Forget, S.; Chenais, S.; Geffroy, B.; Tondelier, D.; Bonnassieux, Y.; Ishow, E.

    2012-02-01

    White light can be obtained from Organic Light Emitting Diodes by mixing three primary colors, (i.e. red, green and blue) or two complementary colors in the emissive layer. In order to improve the efficiency and stability of the devices, a host-guest system is generally used as an emitting layer. However, the color balance to obtain white light is difficult to control and optimize because the spectrum is very sensitive to doping concentration (especially when a small amount of material is used). We use here an ultra-thin mixed emitting layer (UML) deposited by thermal evaporation to fabricate white organic light emitting diodes (WOLEDs) without co-evaporation. The UML was inserted in the hole-transporting layer consisting of 4, 4'-bis[N-(1-naphtyl)-N-phenylamino]biphenyl (α-NPB) instead of using a conventional doping process. The UML was formed from a single evaporation boat containing a mixture of two dipolar starbust triarylamine molecules (fvin and fcho) presenting very similar structures and thermal properties and emitting in complementary spectral regions (orange and blue respectively) and mixed according to their weight ratio. The composition of the UML specifically allows for fine tuning of the emission color despite its very thin thickness down to 1 nm. Competitive energy transfer processes from fcho and the host interface toward fvin are key parameters to control the relative intensity between red and blue emission. White light with very good CIE 1931 color coordinate (0.34, 0.34) was obtained by simply adjusting the UML film composition.

  13. Acoustic Gaits: Gait Analysis With Footstep Sounds.

    PubMed

    Altaf, M Umair Bin; Butko, Taras; Juang, Biing-Hwang Fred

    2015-08-01

    We describe the acoustic gaits-the natural human gait quantitative characteristics derived from the sound of footsteps as the person walks normally. We introduce the acoustic gait profile, which is obtained from temporal signal analysis of sound of footsteps collected by microphones and illustrate some of the spatio-temporal gait parameters that can be extracted from the acoustic gait profile by using three temporal signal analysis methods-the squared energy estimate, Hilbert transform and Teager-Kaiser energy operator. Based on the statistical analysis of the parameter estimates, we show that the spatio-temporal parameters and gait characteristics obtained using the acoustic gait profile can consistently and reliably estimate a subset of clinical and biometric gait parameters currently in use for standardized gait assessments. We conclude that the Teager-Kaiser energy operator provides the most consistent gait parameter estimates showing the least variation across different sessions and zones. Acoustic gaits use an inexpensive set of microphones with a computing device as an accurate and unintrusive gait analysis system. This is in contrast to the expensive and intrusive systems currently used in laboratory gait analysis such as the force plates, pressure mats and wearable sensors, some of which may change the gait parameters that are being measured. PMID:25769144

  14. Pattern-formation under acoustic driving forces

    NASA Astrophysics Data System (ADS)

    Valverde, Jose Manuel

    2015-07-01

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

  15. Physics of thermo-acoustic sound generation

    NASA Astrophysics Data System (ADS)

    Daschewski, M.; Boehm, R.; Prager, J.; Kreutzbruck, M.; Harrer, A.

    2013-09-01

    We present a generalized analytical model of thermo-acoustic sound generation based on the analysis of thermally induced energy density fluctuations and their propagation into the adjacent matter. The model provides exact analytical prediction of the sound pressure generated in fluids and solids; consequently, it can be applied to arbitrary thermal power sources such as thermophones, plasma firings, laser beams, and chemical reactions. Unlike existing approaches, our description also includes acoustic near-field effects and sound-field attenuation. Analytical results are compared with measurements of sound pressures generated by thermo-acoustic transducers in air for frequencies up to 1 MHz. The tested transducers consist of titanium and indium tin oxide coatings on quartz glass and polycarbonate substrates. The model reveals that thermo-acoustic efficiency increases linearly with the supplied thermal power and quadratically with thermal excitation frequency. Comparison of the efficiency of our thermo-acoustic transducers with those of piezoelectric-based airborne ultrasound transducers using impulse excitation showed comparable sound pressure values. The present results show that thermo-acoustic transducers can be applied as broadband, non-resonant, high-performance ultrasound sources.

  16. Towards acoustic UHE neutrino detection in the Mediterranean sea

    NASA Astrophysics Data System (ADS)

    Riccobene, G.

    2012-11-01

    Acoustic detection is proposed as a promising detection technique for Extreme High energy neutrinos. This technique is based on the detection of the acoustic signature of neutrino-induced showers in water: a bipolar signal, having a bandwidth of few 10 kHz, with cylindrical wave front. During the last decade, the possibility of access to deep-sea infrastructures developed for Cherenkov telescopes, allowed start-up of intense R&D activities on acoustic detection. In the framework of the activities of ANTARES, NEMO and KM3NeT, several small size experiments were run in order to measure acoustic noise in deep sea and test “neutrino-like” acoustic event detection. These activities have set milestones both for future HE neutrino detectors, for innovative deep-sea technology and for Earth-Sea science. A review on acoustic neutrino detection and projects running in the Mediterranean Sea is presented.

  17. Waveform inversion of acoustic waves for explosion yield estimation

    NASA Astrophysics Data System (ADS)

    Kim, K.; Rodgers, A.

    2016-07-01

    We present a new waveform inversion technique to estimate the energy of near-surface explosions using atmospheric acoustic waves. Conventional methods often employ air blast models based on a homogeneous atmosphere, where the acoustic wave propagation effects (e.g., refraction and diffraction) are not taken into account, and therefore, their accuracy decreases with increasing source-receiver distance. In this study, three-dimensional acoustic simulations are performed with a finite difference method in realistic atmospheres and topography, and the modeled acoustic Green's functions are incorporated into the waveform inversion for the acoustic source time functions. The strength of the acoustic source is related to explosion yield based on a standard air blast model. The technique was applied to local explosions (<10 km) and provided reasonable yield estimates (<˜30% error) in the presence of realistic topography and atmospheric structure. The presented method can be extended to explosions recorded at far distance provided proper meteorological specifications.

  18. 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.

  19. Acoustic Particle Velocity Sensors: Design, Performance, and Applications Proceedings

    SciTech Connect

    Berliner, M.J.; Lindberg, J.F.

    1996-07-01

    These proceedings represent the papers presented at a workshop sponsored by the Office of Naval Research and the Acoustical Society of America. The topics discussed include designs, applications and performance of underwater acoustic sensors. There were 29 papers presented and all have been abstracted for the Energy Science and Technology database.(AIP)

  20. Methods and apparatus for measurement of the resistivity of geological formations from within cased wells in presence of acoustic and magnetic energy sources

    DOEpatents

    Vail, III, William B.

    1991-01-01

    Methods and apparatus are provided for measuring the acoustically modulated electronic properties of geological formations and cement layers adjacent to cased boreholes. Current is passed from an electrode in electrical contact with the interior of the borehole casing to an electrode on the surface of the earth. Voltage measuring electrodes in electrical contact with the interior of the casing measure the voltage at various points thereon. The voltage differences between discrete pairs of the voltage measuring electrodes provide a measurement of the leakage current conducted into formation in the vicinity of those electrodes. Simultaneously subjecting the casing and formation to an acoustic source acoustically modulates the leakage current measured thereby providing a measure of the acoustically modulated electronic properties of the adjacent formation. Similarly, methods and apparatus are also described which measure the leakage current into formation while simultaneously subjecting the casing to an applied magnetic field which therefore allows measurement of the magnetically modulated electronic properties of the casing and the adjacent formation.

  1. Methods and apparatus for measurement of the resistivity of geological formations from within cased wells in presence of acoustic and magnetic energy sources

    DOEpatents

    Vail, W.B. III.

    1991-08-27

    Methods and apparatus are provided for measuring the acoustically modulated electronic properties of geological formations and cement layers adjacent to cased boreholes. Current is passed from an electrode in electrical contact with the interior of the borehole casing to an electrode on the surface of the earth. Voltage measuring electrodes in electrical contact with the interior of the casing measure the voltage at various points thereon. The voltage differences between discrete pairs of the voltage measuring electrodes provide a measurement of the leakage current conducted into formation in the vicinity of those electrodes. Simultaneously subjecting the casing and formation to an acoustic source acoustically modulates the leakage current measured thereby providing a measure of the acoustically modulated electronic properties of the adjacent formation. Similarly, methods and apparatus are also described which measure the leakage current into formation while simultaneously subjecting the casing to an applied magnetic field which therefore allows measurement of the magnetically modulated electronic properties of the casing and the adjacent formation. 9 figures.

  2. Normal mode solutions for seismo-acoustic propagation resulting from shear and combined wave point sources.

    PubMed

    Nealy, Jennifer L; Collis, Jon M; Frank, Scott D

    2016-04-01

    Normal mode solutions to range-independent seismo-acoustic problems are benchmarked against elastic parabolic equation solutions and then used to benchmark the shear elastic parabolic equation self-starter [Frank, Odom, and Collis, J. Acoust. Soc. Am. 133, 1358-1367 (2013)]. The Pekeris waveguide with an elastic seafloor is considered for a point source located in the ocean emitting compressional waves, or in the seafloor, emitting both compressional and shear waves. Accurate solutions are obtained when the source is in the seafloor, and when the source is at the interface between the fluid and elastic layers. PMID:27106346

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

    NASA Astrophysics Data System (ADS)

    Viola, S.; Ardid, M.; Bertin, V.; Enzenhöfer, A.; Keller, P.; Lahmann, R.; Larosa, G.; Llorens, C. D.; NEMO Collaboration; SMO Collaboration

    2013-10-01

    Within the activities of the NEMO project, the installation of a 8-floors tower (NEMO-Phase II) at a depth of 3500 m is foreseen in 2012. The tower will be installed about 80 km off-shore Capo Passero, in Sicily. On board the NEMO tower, an array of 18 acoustic sensors will be installed, permitting acoustic detection of biological sources, studies for acoustic neutrino detection and primarily acoustic positioning of the underwater structures. For the latter purpose, the sensors register acoustic signals emitted by five acoustic beacons anchored on the sea-floor. The data acquisition system of the acoustic sensors is fully integrated with the detector data transport system and is based on an “all data to shore” philosophy. Signals coming from hydrophones are continuously sampled underwater at 192 kHz/24 bit and transmitted to shore through an electro-optical cable for real-time analysis. A novel technology for underwater GPS time-stamping of data has been implemented and tested. The operation of the acoustic array will permit long-term test of sensors and electronics technologies that are proposed for the acoustic positioning system of KM3NeT.

  4. Comparison of Acoustic Energy Meter (AEM) and Schmidt hammer 'R' for rapid assessment of rock surface hardness: a preliminary assessment from southeast Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Brook, Martin; Winkler, Stefan

    2015-04-01

    This research focuses on one of the key challenges in geomorphology - quantifying rock surface hardness via in situ measurements, to provide information on rock physical properties. This has been a focus in recent years with the rapid emergence of studies that center on surface and near surface weathering impacts, and rates of material loss. Indeed, a key element to understanding how weathering and erosion processes combine to influence rock surface (and landscape) evolution is the measurement and monitoring of rock surface hardness. We provide results from a preliminary assessment of the applicability of the Acoustic Energy Meter (AEM) to subaerial rock surface hardness, in comparison with an N-Type Schmidt hammer. The AEM apparatus consists of a geophone which is in contact with the rock surface and some electronics. The AEM is held normal to the surface to be tested and the surface is struck with a small hammer (typically 0.75 kg), with the AEM quantifying the decay time of seismically-induced oscillations within the top c. 1-2 m of the rock mass. Previous work using an AEM has focused on measuring roof stability and delamination in South African underground coal, gold and platinum mines, where long AEM reverberation times correlated well with weak rock mass and dense microfracturing. However, the technique has rarely been applied to the assessment of rock surfaces in a subaerial setting. We applied the technique to a range of lithologies at five sites in southeast Queensland in the Brisbane area, each an exposure of phyllite, granite, mudstone, argillite or volcanic tuff. The aims were: (1) quantifying the response of different rock masses to the AEM technique; and (2) assessing the applicability of the AEM as a rapid in situ measure of rock hardness by comparing results with Schmidt hammer 'R' values from the same exposures. Results showed that the AEM is useful in discriminating rock hardness across rocks with different lithological properties. Second, an

  5. 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.

  6. 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.

  7. Motion measurement of acoustically levitated object

    NASA Technical Reports Server (NTRS)

    Watkins, John L. (Inventor); Barmatz, Martin B. (Inventor)

    1993-01-01

    A system is described for determining motion of an object that is acoustically positioned in a standing wave field in a chamber. Sonic energy in the chamber is sensed, and variation in the amplitude of the sonic energy is detected, which is caused by linear motion, rotational motion, or drop shape oscillation of the object. Apparatus for detecting object motion can include a microphone coupled to the chamber and a low pass filter connected to the output of the microphone, which passes only frequencies below the frequency of sound produced by a transducer that maintains the acoustic standing wave field. Knowledge about object motion can be useful by itself, can be useful to determine surface tension, viscosity, and other information about the object, and can be useful to determine the pressure and other characteristics of the acoustic field.

  8. Topological charge pump by surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Yi, Zheng; Shi-Ping, Feng; Shi-Jie, Yang

    2016-06-01

    Quantized electron pumping by the surface acoustic wave across barriers created by a sequence of split metal gates is interpreted from the viewpoint of topology. The surface acoustic wave serves as a one-dimensional periodical potential whose energy spectrum possesses the Bloch band structure. The time-dependent phase plays the role of an adiabatic parameter of the Hamiltonian which induces a geometrical phase. The pumping currents are related to the Chern numbers of the filled bands below the Fermi energy. Based on this understanding, we predict a novel effect of quantized but non-monotonous current plateaus simultaneously pumped by two homodromous surface acoustic waves. Project supported by the National Natural Science Foundation of China (Grant No. 11374036) and the National Basic Research Program of China (Grant No. 2012CB821403).

  9. 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.

  10. Architectural shape and early acoustic efficiency in concert halls (L).

    PubMed

    Jurkiewicz, Yann; Wulfrank, Thomas; Kahle, Eckhard

    2012-09-01

    Supplying sufficient early reflections to audience members is an important prerequisite to good acoustic quality in performing arts spaces. However, the relationship between the geometry of a room and its acoustic efficiency in terms of early energy has rarely been investigated using basic geometrical principles. The present study demonstrates the possibility of predicting the average value of early reflected energy across the audience area using solid angles. The formulas obtained display the influence of various factors on average early energy; in particular, the direction of arrival of early reflections is found to play a significant role, which highlights interesting implications for the acoustic design of concert halls. PMID:22978852

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Acoustic signals of baby black caimans.

    PubMed

    Vergne, Amélie L; Aubin, Thierry; Taylor, Peter; Mathevon, Nicolas

    2011-12-01

    In spite of the importance of crocodilian vocalizations for the understanding of the evolution of sound communication in Archosauria and due to the small number of experimental investigations, information concerning the vocal world of crocodilians is limited. By studying black caimans Melanosuchus niger in their natural habitat, here we supply the experimental evidence that juvenile crocodilians can use a graded sound system in order to elicit adapted behavioral responses from their mother and siblings. By analyzing the acoustic structure of calls emitted in two different situations ('undisturbed context', during which spontaneous calls of juvenile caimans were recorded without perturbing the group, and a simulated 'predator attack', during which calls were recorded while shaking juveniles) and by testing their biological relevance through playback experiments, we reveal the existence of two functionally different types of juvenile calls that produce a different response from the mother and other siblings. Young black caimans can thus modulate the structure of their vocalizations along an acoustic continuum as a function of the emission context. Playback experiments show that both mother and juveniles discriminate between these 'distress' and 'contact' calls. Acoustic communication is thus an important component mediating relationships within family groups in caimans as it is in birds, their archosaurian relatives. Although probably limited, the vocal repertoire of young crocodilians is capable of transmitting the information necessary for allowing siblings and mother to modulate their behavior. PMID:21978842

  16. Distribution of Acoustic Power Spectra for an Isolated Helicopter Fuselage

    NASA Astrophysics Data System (ADS)

    Kusyumov, A. N.; Mikhailov, S. A.; Garipova, L. I.; Batrakov, A. S.; Barakos, G.

    2016-03-01

    The broadband aerodynamic noise can be studied, assuming isotropic flow, turbulence and decay. Proudman's approach allows practical calculations of noise based on CFD solutions of RANS or URANS equations at the stage of post processing and analysis of the solution. Another aspect is the broadband acoustic spectrum and the distribution of acoustic power over a range of frequencies. The acoustic energy spectrum distribution in isotropic turbulence is non monotonic and has a maximum at a certain value of Strouhal number. In the present work the value of acoustic power peak frequency is determined using a prescribed form of acoustic energy spectrum distribution presented in papers by S. Sarkar and M. Y. Hussaini and by G. M. Lilley. CFD modelling of the flow around isolated helicopter fuselage model was considered using the HMB CFD code and the RANS equations.

  17. Acoustic-velocity measurements in materials using a regenerative method

    DOEpatents

    Laine, E.F.

    1982-09-30

    Acoustic energy is propatated through earth material between an electro-acoustic generator and a receiver which converts the received acoustic energy into electrical signals. A closed loop is formed by a variable gain amplifier system connected between the receiver and the generator. The gain of the amplifier system is increased until sustained oscillations are produced in the closed loop. The frequency of the oscillations is measured as an indication of the acoustic propagation velocity through the earth material. The amplifier gain is measured as an indication of the acoustic attenuation through the earth materials. The method is also applicable to the non-destructive testing of structural materials, such as steel, aluminum and concrete.

  18. Acoustic velocity measurements in materials using a regenerative method

    DOEpatents

    Laine, Edwin F.

    1986-01-01

    Acoustic energy is propagated through earth material between an electro-acoustic generator and a receiver which converts the received acoustic energy into electrical signals. A closed loop is formed by a variable gain amplifier system connected between the receiver and the generator. The gain of the amplifier system is increased until sustained oscillations are produced in the closed loop. The frequency of the oscillations is measured as an indication of the acoustic propagation velocity through the earth material. The amplifier gain is measured as an indication of the acoustic attenuation through the earth materials. The method is also applicable to the non-destructive testing of structural materials, such as steel, aluminum and concrete.

  19. Selective optical generation of a coherent acoustic nanocavity mode

    NASA Astrophysics Data System (ADS)

    Pascual Winter, M. F.; Rozas, G.; Jusserand, B.; Perrin, B.; Fainstein, A.; Vaccaro, P. O.; Saravanan, S.

    2007-04-01

    We report the first experimental evidence of selective generation of a confined acoustic mode in a Ga0.85In0.15As nanocavity enclosed by two Ga0.85In0.15As/AlAs phonon Bragg mirrors. Femtosecond pump-probe experiments reveal the generation of a cavity mode within the acoustic mini-gap of the mirrors, in addition to their folded acoustic modes. Selective generation of the confined mode alone is achievable for certain energies below the absorption of the quantum wells in the phonon mirrors. These energies are experimentally identified with the cavity spacer electronic transitions. The amplitude of the acoustic nanocavity mode can be controlled by detuning the excitation from the spacer transitions. The present work finds a direct interest in the seek of monochromatic MHz-THz acoustic sources.

  20. 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 ...

  1. 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.

  2. Acoustic imaging system

    DOEpatents

    Smith, Richard W.

    1979-01-01

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

  3. 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.

  4. 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.

  5. 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.

  6. A highly efficient white light (Sr3,Ca,Ba)(PO4)3Cl:Eu2+, Tb3+, Mn2+ phosphor via dual energy transfers for white light-emitting diodes.

    PubMed

    Chen, Xi; Dai, Pengpeng; Zhang, Xintong; Li, Cong; Lu, Shan; Wang, Xiuli; Jia, Yan; Liu, Yichun

    2014-04-01

    A series of single-phased (Sr3-x,Ca1-y-z,Ba)(PO4)3Cl (SCBPO_Cl):xEu(2+), yTb(3+), zMn(2+) phosphors were synthesized by high-temperature solid-state reaction, and luminescent properties of these phosphors were investigated by means of photoluminescence and microcathode luminescence (μ-CL). Under UV excitation, white-light emission was obtained from triactivated SCBPO_Cl phosphors via combining three emission bands centered at 450, 543, and 570 nm contributed by Eu(2+), Tb(3+), and Mn(2+), respectively. White-light emission with the three emission bands is further demonstrated in the fluorescence microscope images, CL spectrum, and μ-CL mappings, which strongly confirm that the luminescence distribution of as-prepared SCBPO_Cl:xEu(2+), yTb(3+), zMn(2+) phosphors is very homogeneous. Both spectral overlapping and lifetime decay analyses suggest that dual energy transfers, that is, Eu(2+)→Tb(3+) and Eu(2+)→Mn(2+), play key roles in obtaining the white emission. The International Commission on Illumination value of white emission as well as luminescence quantum yield (51.2-81.4%) can be tuned by precisely controlling the content of Eu(2+), Tb(3+), and Mn(2+). These results suggest that this single-phased SCBPO_Cl:xEu(2+), yTb(3+), zMn(2+) phosphor may have a potential application as a near-UV convertible white-light emission phosphor for phosphor-converted white light-emitting diode. PMID:24649898

  7. 850-nm Zn-diffusion vertical-cavity surface-emitting lasers with with oxide-relief structure for high-speed and energy-efficient optical interconnects from very-short to medium (2km) reaches

    NASA Astrophysics Data System (ADS)

    Shi, Jin-Wei; Wei, Chia-Chien; Chen, Jason (Jyehong); Yang, Ying-Jay

    2015-03-01

    High-speed and "green" ~850 nm vertical-cavity surface-emitting lasers (VCSELs) have lately attracted lots of attention due to their suitability for applications in optical interconnects (OIs). To further enhance the speed and its maximum allowable linking distance of VCSELs are two major trends to meet the requirement of OI in next generation data centers. Recently, by use of the advanced 850 nm VCSEL technique, data rate as high as 64 Gbit/sec over 57m and 20 Gbit/sec over 2km MMF transmission have been demonstrated, respectively. Here, we will review our recent work about 850 nm Zn-diffusion VCSELs with oxide-relief apertures to further enhance the above-mentioned performances. By using Zn-diffusion, we can not only reduce the device resistance but also manipulate the number of optical modes to benefit transmission. Combing such device, which has excellent single-mode (SMSR >30 dB) and high-power (~7mW) performance, with advanced modulation format (OFDM), record-high bit-rate-distance-product through MMF (2.3 km×28 Gbit/sec) has been demonstrated. Furthermore, by selective etching away the oxide aperture inside Zn-diffusion VCSEL, significant enhancement of device speed, D-factor, and reliability can be observed. With such unique VCSEL structure, >40 Gbit/sec energy-efficient transmission over 100m MMF under extremely low-driving current density (<10kA/cm2) has been successfully demonstrated.

  8. Quantum Dot Light Emitting Diode

    SciTech Connect

    Keith Kahen

    2008-07-31

    The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m2, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

  9. Quantum Dot Light Emitting Diode

    SciTech Connect

    Kahen, Keith

    2008-07-31

    The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m{sup 2}, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

  10. Directivity patterns and pulse profiles of ultrasound emitted by laser action on interface between transparent and opaque solids: Analytical theory

    SciTech Connect

    Nikitin, Sergey M. E-mail: vitali.goussev@univ-lemans.fr; Tournat, Vincent; Chigarev, Nikolay; Castagnede, Bernard; Gusev, Vitalyi E-mail: vitali.goussev@univ-lemans.fr; Bulou, Alain; Zerr, Andreas

    2014-01-28

    The analytical theory for the directivity patterns of ultrasounds emitted from laser-irradiated interface between two isotropic solids is developed. It is valid for arbitrary combinations of transparent and opaque materials. The directivity patterns are derived both in two-dimensional and in three-dimensional geometries, by accounting for the specific features of the sound generation by the photo-induced mechanical stresses distributed in the volume, essential in the laser ultrasonics. In particular, the theory accounts for the contribution to the emitted propagating acoustic fields from the converted by the interface evanescent photo-generated compression-dilatation waves. The precise analytical solutions for the profiles of longitudinal and shear acoustic pulses emitted in different directions are proposed. The developed theory can be applied for dimensional scaling, optimization, and interpretation of the high-pressure laser ultrasonics experiments in diamond anvil cell.

  11. Porous light-emitting compositions

    DOEpatents

    Burrell, Anthony K.; McCleskey, Thomas Mark; Jia, Quanxi; Bauer, Eve; Mueller, Alexander H.

    2012-04-17

    Light-emitting devices are prepared by coating a porous substrate using a polymer-assisted deposition process. Solutions of metal precursor and soluble polymers having binding properties for metal precursor were coated onto porous substrates. The coated substrates were heated at high temperatures under a suitable atmosphere. The result was a substrate with a conformal coating that did not substantially block the pores of the substrate.

  12. 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.

  13. 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

  14. Acoustic underwater signals with a probable function during competitive feeding in a tadpole

    NASA Astrophysics Data System (ADS)

    Reeve, Erik; Ndriantsoa, Serge Herilala; Strauß, Axel; Randrianiaina, Roger-Daniel; Rasolonjatovo Hiobiarilanto, Tahiry; Glaw, Frank; Glos, Julian; Vences, Miguel

    2011-02-01

    Acoustic communication is widespread among adult stages of terrestrial animals and fish and has also been observed in insect larvae. We report underwater acoustic communication in the larvae of a frog, Gephyromantis azzurrae, from Isalo, a sandstone massif in western Madagascar. According to our field data, these tadpoles live in streams and prefer habitats characterized by comparatively low temperatures, shallow water depth, and a relatively fast current. Feeding experiments indicated that the tadpoles are carnivorous and macrophagous. They consumed insect larvae and, to a lesser extent, small shrimps, and conspecific as well as heterospecific tadpoles. Calls of these tadpoles consisted either of single click notes or of irregular series of various clicks. Some complex calls have a pulsed structure with three to nine indistinct energy pulses. Production of the pulses coincided with rapid closure of the jaw sheaths and often with an upward movement of the body. Calls were emitted while attacking prey and occurred significantly more often when attacking conspecifics. Tadpoles that had not been fed for some time emitted sounds more frequently than those that had been regularly fed. The spectral frequency of the calls differed in tadpole groups of different size and was higher in groups of smaller tadpoles, suggesting that spectral frequency carries some information about tadpole size which might be important during competitive feeding to assess size and strength of competitors. This report differs from those for the larvae of South American horned frogs, Ceratophrys ornata. These are the only other tadpoles for which sound production has reliably been reported but the calls of Ceratophrys tadpoles occur mainly in a defensive context.

  15. White light-emitting organic electroluminescent devices

    DOEpatents

    Shiang, Joseph John; Duggal, Anil Raj; Parthasarathy, Gautam

    2006-06-20

    A light-emitting device comprises a light-emitting member, which comprises two electrodes, at least two organic electroluminescent ("EL") materials disposed between the electrodes, a charge blocking material disposed between the electrodes, and at least one photoluminescent ("PL") material. The light-emitting member emits electromagnetic ("EM") radiation having a first spectrum in response to a voltage applied across the two electrodes. The PL material absorbs a portion of the EM radiation emitted by the light-emitting member and emits EM radiation having second spectrum different than the first spectrum. Each of the organic EL materials emits EM radiation having a wavelength range selected from the group consisting of blue and red wavelength ranges.

  16. 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.

  17. 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

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

    SciTech Connect

    Reethof, G.; McDaniel, O.H.

    1982-01-01

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

  19. Acoustic Noise Prediction of the Amine Swingbed ISS ExPRESS Rack Payload

    NASA Technical Reports Server (NTRS)

    Welsh, David; Smith, Holly; Wang, Shuo

    2010-01-01

    Acoustics plays a vital role in maintaining the health, safety, and comfort of crew members aboard the International Space Station (ISS). In order to maintain this livable and workable environment, acoustic requirements have been established to ensure that ISS hardware and payload developers account for the acoustic emissions of their equipment and develop acoustic mitigations as necessary. These requirements are verified by an acoustic emissions test of the integrated hardware. The Amine Swingbed ExPRESS (Expedite the PRocessing of ExperimentS to Space) rack payload creates a unique challenge to the developers in that the payload hardware is transported to the ISS in phases, making an acoustic emissions test on the integrated flight hardware impossible. In addition, the payload incorporates a high back pressure fan and a diaphragm vacuum pump, which are recognized as significant and complex noise sources. In order to accurately predict the acoustic emissions of the integrated payload, the individual acoustic noise sources and paths are first characterized. These characterizations are conducted though a series of acoustic emissions tests on the individual payload components. Secondly, the individual acoustic noise sources and paths are incorporated into a virtual model of the integrated hardware. The virtual model is constructed with the use of hybrid method utilizing the Finite Element Acoustic (FEA) and Statistical Energy Analysis (SEA) techniques, which predict the overall acoustic emissions. Finally, the acoustic model is validated though an acoustic characterization test performed on an acoustically similar mock-up of the flight unit. The results of the validated acoustic model are then used to assess the acoustic emissions of the flight unit and define further acoustic mitigation efforts.

  20. Frequency dependence of the acoustic field generated from a spherical cavity transducer with open ends

    SciTech Connect

    Li, Faqi; Zeng, Deping; He, Min; Wang, Zhibiao E-mail: wangzhibiao@haifu.com.cn; Song, Dan; Lei, Guangrong; Lin, Zhou; Zhang, Dong E-mail: wangzhibiao@haifu.com.cn; Wu, Junru

    2015-12-15

    Resolution of high intensity focused ultrasound (HIFU) focusing is limited by the wave diffraction. We have developed a spherical cavity transducer with two open ends to improve the focusing precision without sacrificing the acoustic intensity (App Phys Lett 2013; 102: 204102). This work aims to theoretically and experimentally investigate the frequency dependence of the acoustic field generated from the spherical cavity transducer with two open ends. The device emits high intensity ultrasound at the frequency ranging from 420 to 470 kHz, and the acoustic field is measured by a fiber optic probe hydrophone. The measured results shows that the spherical cavity transducer provides high acoustic intensity for HIFU treatment only in its resonant modes, and a series of resonant frequencies can be choosen. Furthermore, a finite element model is developed to discuss the frequency dependence of the acoustic field. The numerical simulations coincide well with the measured results.