Science.gov

Sample records for acoustic power level

  1. Correlation of combustor acoustic power levels inferred from internal fluctuating pressure measurements

    NASA Technical Reports Server (NTRS)

    Vonglahn, U. H.

    1978-01-01

    Combustion chamber acoustic power levels inferred from internal fluctuating pressure measurements are correlated with operating conditions and chamber geometries over a wide range. The variables include considerations of chamber design (can, annular, and reverse-flow annular) and size, number of fuel nozzles, burner staging and fuel split, airflow and heat release rates, and chamber inlet pressure and temperature levels. The correlated data include those obtained with combustion component development rigs as well as engines.

  2. Near-Field Acoustic Power Level Analysis of F31/A31 Open Rotor Model at Simulated Cruise Conditions, Technical Report II

    NASA Technical Reports Server (NTRS)

    Sree, Dave

    2015-01-01

    Near-field acoustic power level analysis of F31A31 open rotor model has been performed to determine its noise characteristics at simulated cruise flight conditions. The non-proprietary parts of the test data obtained from experiments in the 8x6 supersonic wind tunnel were provided by NASA-Glenn Research Center. The tone and broadband components of total noise have been separated from raw test data by using a new data analysis tool. Results in terms of sound pressure levels, acoustic power levels, and their variations with rotor speed, freestream Mach number, and input shaft power, with different blade-pitch setting angles at simulated cruise flight conditions, are presented and discussed. Empirical equations relating models acoustic power level and input shaft power have been developed. The near-field acoustic efficiency of the model at simulated cruise conditions is also determined. It is hoped that the results presented in this work will serve as a database for comparison and improvement of other open rotor blade designs and also for validating open rotor noise prediction codes.

  3. Powered-Lift Aerodynamics and Acoustics. [conferences

    NASA Technical Reports Server (NTRS)

    1976-01-01

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

  4. Far-Field Acoustic Power Level and Performance Analyses of F31/A31 Open Rotor Model at Simulated Scaled Takeoff, Nominal Takeoff, and Approach Conditions: Technical Report I

    NASA Technical Reports Server (NTRS)

    Sree, Dave

    2015-01-01

    Far-field acoustic power level and performance analyses of open rotor model F31/A31 have been performed to determine its noise characteristics at simulated scaled takeoff, nominal takeoff, and approach flight conditions. The nonproprietary parts of the data obtained from experiments in 9- by 15-Foot Low-Speed Wind Tunnel (9?15 LSWT) tests were provided by NASA Glenn Research Center to perform the analyses. The tone and broadband noise components have been separated from raw test data by using a new data analysis tool. Results in terms of sound pressure levels, acoustic power levels, and their variations with rotor speed, angle of attack, thrust, and input shaft power have been presented and discussed. The effect of an upstream pylon on the noise levels of the model has been addressed. Empirical equations relating model's acoustic power level, thrust, and input shaft power have been developed. The far-field acoustic efficiency of the model is also determined for various simulated flight conditions. It is intended that the results presented in this work will serve as a database for comparison and improvement of other open rotor blade designs and also for validating open rotor noise prediction codes.

  5. Development and testing of cabin sidewall acoustic resonators for the reduction of cabin tone levels in propfan-powered aircraft

    NASA Technical Reports Server (NTRS)

    Kuntz, H. L.; Gatineau, R. J.; Prydz, R. A.; Balena, F. J.

    1991-01-01

    The use of Helmholtz resonators to increase the sidewall transmission loss (TL) in aircraft cabin sidewalls is evaluated. Development, construction, and test of an aircraft cabin acoustic enclosure, built in support of the Propfan Test Assessment (PTA) program, is described. Laboratory and flight test results are discussed. Resonators (448) were located between the enclosure trim panels and the fuselage shell. In addition, 152 resonators were placed between the enclosure and aircraft floors. The 600 resonators were each tuned to a propfan fundamental blade passage frequency (235 Hz). After flight testing on the PTA aircraft, noise reduction (NR) tests were performed with the enclosure in the Kelly Johnson Research and Development Center Acoustics Laboratory. Broadband and tonal excitations were used in the laboratory. Tonal excitation simulated the propfan flight test excitation. The resonators increase the NR of the cabin walls around the resonance frequency of the resonator array. Increases in NR of up to 11 dB were measured. The effects of flanking, sidewall absorption, cabin absorption, resonator loading of trim panels, and panel vibrations are presented. Resonator and sidewall panel design and test are discussed.

  6. Acoustic Power Transmission Through a Ducted Fan

    NASA Technical Reports Server (NTRS)

    Envia, Ed

    2016-01-01

    For high-speed ducted fans, when the rotor flowfield is shock-free, the main contribution to the inlet radiated acoustic power comes from the portion of the rotor stator interaction sound field that is transmitted upstream through the rotor. As such, inclusion of the acoustic transmission is an essential ingredient in the prediction of the fan inlet noise when the fan tip relative speed is subsonic. This paper describes a linearized Euler based approach to computing the acoustic transmission of fan tones through the rotor. The approach is embodied in a code called LINFLUX was applied to a candidate subsonic fan called the Advanced Ducted Propulsor (ADP). The results from this study suggest that it is possible to make such prediction with sufficient fidelity to provide an indication of the acoustic transmission trends with the fan tip speed.

  7. Measurement of the total acoustic output power of HITU transducers

    NASA Astrophysics Data System (ADS)

    Jenderka, Klaus-V.; Beissner, Klaus

    2010-03-01

    The majority of High Intensity Therapeutic Ultrasound (HITU) applications use strongly focused ultrasound fields generating very high local intensities in the focal region. The metrology of these high-power ultrasound fields is a challenge for the established measurement procedures and devices. This paper describes the results of measurements by means of the radiation force for a total acoustic output power up to 400 W at 1.5 MHz and up to 200 W at 2.45 MHz. For this purpose, a radiation force balance set-up was adapted for the determination of large acoustic output powers. For two types of HITU transducers, the relationship between the total acoustic output power and the applied net electrical power was determined at close transducer-target distance. Further, dependence of the measured electro-acoustic radiation conductance on the transducer-target distance was investigated at reduced power levels, considering the appearance of focal anomalies. Concluding, a list of the main uncertainty contributions, and an estimate of the uncertainty for the used radiation force balance set-up is given for measurements at high power levels.

  8. Selectively manipulable acoustic-powered microswimmers.

    PubMed

    Ahmed, Daniel; Lu, Mengqian; Nourhani, Amir; Lammert, Paul E; Stratton, Zak; Muddana, Hari S; Crespi, Vincent H; Huang, Tony Jun

    2015-05-20

    Selective actuation of a single microswimmer from within a diverse group would be a first step toward collaborative guided action by a group of swimmers. Here we describe a new class of microswimmer that accomplishes this goal. Our swimmer design overcomes the commonly-held design paradigm that microswimmers must use non-reciprocal motion to achieve propulsion; instead, the swimmer is propelled by oscillatory motion of an air bubble trapped within the swimmer's polymer body. This oscillatory motion is driven by the application of a low-power acoustic field, which is biocompatible with biological samples and with the ambient liquid. This acoustically-powered microswimmer accomplishes controllable and rapid translational and rotational motion, even in highly viscous liquids (with viscosity 6,000 times higher than that of water). And by using a group of swimmers each with a unique bubble size (and resulting unique resonance frequencies), selective actuation of a single swimmer from among the group can be readily achieved.

  9. PREDICTIVE MODELING OF ACOUSTIC SIGNALS FROM THERMOACOUSTIC POWER SENSORS (TAPS)

    SciTech Connect

    Dumm, Christopher M.; Vipperman, Jeffrey S.

    2016-06-30

    Thermoacoustic Power Sensor (TAPS) technology offers the potential for self-powered, wireless measurement of nuclear reactor core operating conditions. TAPS are based on thermoacoustic engines, which harness thermal energy from fission reactions to generate acoustic waves by virtue of gas motion through a porous stack of thermally nonconductive material. TAPS can be placed in the core, where they generate acoustic waves whose frequency and amplitude are proportional to the local temperature and radiation flux, respectively. TAPS acoustic signals are not measured directly at the TAPS; rather, they propagate wirelessly from an individual TAPS through the reactor, and ultimately to a low-power receiver network on the vessel’s exterior. In order to rely on TAPS as primary instrumentation, reactor-specific models which account for geometric/acoustic complexities in the signal propagation environment must be used to predict the amplitude and frequency of TAPS signals at receiver locations. The reactor state may then be derived by comparing receiver signals to the reference levels established by predictive modeling. In this paper, we develop and experimentally benchmark a methodology for predictive modeling of the signals generated by a TAPS system, with the intent of subsequently extending these efforts to modeling of TAPS in a liquid sodium environmen

  10. Method of measuring reactive acoustic power density in a fluid

    DOEpatents

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

    1985-09-03

    A method for determining reactive acoustic power density level and its direction in a fluid using a single sensor is disclosed. In the preferred embodiment, an apparatus for conducting the method, which is termed a thermoacoustic couple, consists of a stack of thin, spaced apart polymeric plates, selected ones of which include multiple bimetallic thermocouple junctions positioned along opposite end edges thereof. The thermocouple junctions are connected in series in the nature of a thermopile, and are arranged so as to be responsive to small temperature differences between the opposite edges of the plates. The magnitude of the temperature difference, as represented by the magnitude of the electrical potential difference generated by the thermopile, is found to be directly related to the level of acoustic power density in the gas. 5 figs.

  11. Method of measuring reactive acoustic power density in a fluid

    DOEpatents

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

    1985-01-01

    A method for determining reactive acoustic power density level and its direction in a fluid using a single sensor is disclosed. In the preferred embodiment, an apparatus for conducting the method, which is termed a thermoacoustic couple, consists of a stack of thin, spaced apart polymeric plates, selected ones of which include multiple bimetallic thermocouple junctions positioned along opposite end edges thereof. The thermocouple junctions are connected in series in the nature of a thermopile, and are arranged so as to be responsive to small temperature differences between the opposite edges of the plates. The magnitude of the temperature difference, as represented by the magnitude of the electrical potential difference generated by the thermopile, is found to be directly related to the level of acoustic power density in the gas.

  12. Selectively manipulable acoustic-powered microswimmers

    PubMed Central

    Ahmed, Daniel; Lu, Mengqian; Nourhani, Amir; Lammert, Paul E.; Stratton, Zak; Muddana, Hari S.; Crespi, Vincent H.; Huang, Tony Jun

    2015-01-01

    Selective actuation of a single microswimmer from within a diverse group would be a first step toward collaborative guided action by a group of swimmers. Here we describe a new class of microswimmer that accomplishes this goal. Our swimmer design overcomes the commonly-held design paradigm that microswimmers must use non-reciprocal motion to achieve propulsion; instead, the swimmer is propelled by oscillatory motion of an air bubble trapped within the swimmer's polymer body. This oscillatory motion is driven by the application of a low-power acoustic field, which is biocompatible with biological samples and with the ambient liquid. This acoustically-powered microswimmer accomplishes controllable and rapid translational and rotational motion, even in highly viscous liquids (with viscosity 6,000 times higher than that of water). And by using a group of swimmers each with a unique bubble size (and resulting unique resonance frequencies), selective actuation of a single swimmer from among the group can be readily achieved. PMID:25993314

  13. Low power acoustic harvesting of aerosols

    SciTech Connect

    Kaduchak, G.; Sinha, D. N.

    2001-01-01

    A new acoustic device for levitation and/or concentration of aerosols and sniall liquid/solid samples (up to several millimeters in diameter) in air has been developed. The device is inexpensive, low-power, and, in its simplest embodiment, does not require accurate alignmen1 of a resonant cavity. It is constructed from a cylindrical PZT tube of outside diameter D = 19.0 mm and thickness-to-radius ratio h/a - 0.03. The lowest-order breathing mode of the tube is tuned to match a resonant mode of the interior air-filled cylindrical cavity. A high Q cavity results that can be driven efficiently. An acoustic standing wave is created in the inteirior cavity of the cylindrical shell where particle concrmtration takes place at the nodal planes of the field. It is shown that drops of water in excess of 1 mm in diameter may be levitated against the force of gravity for approxirnately 100 mW of input electrical power. The main objective of the research is to implement this lowpower device to concentrate and harvest aerosols in a flowing system. Several different cavity geonietries iwe presented for efficient collection of 1 he conaartratetl aerosols. Concentraiion factors greater than 40 iue demonstrated for particles of size 0.7 1.1 in a flow volume of 50 L/minute.

  14. 76 FR 52734 - Underwater Locating Devices (Acoustic) (Self-Powered)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-23

    ...This notice announces the planned revocation of all Technical Standard Order authorizations (TSOA) issued for the production of Underwater Locating Devices (Acoustic) (Self-Powered) manufactured to the TSO-C121 and TSO-C121a specifications. These actions are necessary because the planned issuance of TSO-C121b, Underwater Locating Devices (Acoustic) (Self-Powered), with a minimum performance......

  15. 77 FR 13174 - Underwater Locating Devices (Acoustic) (Self-Powered)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-05

    ...This is a confirmation notice for the planned revocation of all Technical Standard Order authorizations issued for the production of Underwater Locating Devices (Acoustic) (Self-Powered) manufactured to the TSO-C121 and TSO-C121a specifications. These actions are necessary because the planned issuance of TSO-C121b, Underwater Locating Devices (Acoustic) (Self-Powered), minimum performance......

  16. Acoustic power in non-uniform lined ducts

    NASA Astrophysics Data System (ADS)

    Eversman, Walter

    2008-06-01

    A definition of acoustic power in conservation form in lined infinitely long uniform ducts is extended to include axially symmetric non-uniform ducts with potential mean flow and finite length lining. The definition includes a contribution at the lined boundary. Benchmarking is accomplished by verification of acoustic power conservation in the case of a purely reactive lining. Calculations in the case of reactively lined ducts show that intense acoustic gradients near the lined surface can occur, and contributions to acoustic power from the boundary power term become relatively large. This observed behavior diminishes as the resistive component of lining impedance is increased. Power calculations for propagation and radiation from a typical turbo-fan inlet and equivalent calculations for an infinite duct propagation model of the same inlet contour are compared. Results are remarkably similar for the case considered, though it is noted that this conclusion is geometry dependent.

  17. Reversing pathologically increased EEG power by acoustic coordinated reset neuromodulation

    PubMed Central

    Adamchic, Ilya; Toth, Timea; Hauptmann, Christian; Tass, Peter Alexander

    2014-01-01

    Acoustic Coordinated Reset (CR) neuromodulation is a patterned stimulation with tones adjusted to the patient's dominant tinnitus frequency, which aims at desynchronizing pathological neuronal synchronization. In a recent proof-of-concept study, CR therapy, delivered 4–6 h/day more than 12 weeks, induced a significant clinical improvement along with a significant long-lasting decrease of pathological oscillatory power in the low frequency as well as γ band and an increase of the α power in a network of tinnitus-related brain areas. As yet, it remains unclear whether CR shifts the brain activity toward physiological levels or whether it induces clinically beneficial, but nonetheless abnormal electroencephalographic (EEG) patterns, for example excessively decreased δ and/or γ. Here, we compared the patients' spontaneous EEG data at baseline as well as after 12 weeks of CR therapy with the spontaneous EEG of healthy controls by means of Brain Electrical Source Analysis source montage and standardized low-resolution brain electromagnetic tomography techniques. The relationship between changes in EEG power and clinical scores was investigated using a partial least squares approach. In this way, we show that acoustic CR neuromodulation leads to a normalization of the oscillatory power in the tinnitus-related network of brain areas, most prominently in temporal regions. A positive association was found between the changes in tinnitus severity and the normalization of δ and γ power in the temporal, parietal, and cingulate cortical regions. Our findings demonstrate a widespread CR-induced normalization of EEG power, significantly associated with a reduction of tinnitus severity. PMID:23907785

  18. High-Power Piezoelectric Acoustic-Electric Power Feedthru for Metal Walls

    NASA Technical Reports Server (NTRS)

    Bao, Xiaoqi; Biederman, Will; Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Jones, Christopher; Aldrich, Jack; Chang, Zensheu

    2008-01-01

    Piezoelectric acoustic-electric power feed-through devices transfer electric power wirelessly through a solid wall by using acoustic waves. This approach allows for the removal of holes through structures. The technology is applicable to power supply for electric equipment inside sealed containers, vacuum or pressure vessels, etc where the holes on the wall are prohibitive or result in significant performance degrade or complex designs. In the author's previous work, 100-W electric power was transferred through a metal wall by a small, simple-structure piezoelectric device. To meet requirements of higher power applications, the feasibility to transfer kilowatts level power was investigated. Pre-stressed longitudinal piezoelectric feedthru devices were analyzed by finite element model. An equivalent circuit model was developed to predict the power transfer characteristics to different electric loads. Based on the analysis results, a prototype device was designed, fabricated and a demonstration of the transmission of electric power up to 1-kW was successfully conducted. The methods to minimize the plate wave excitation on the wall were also analyzed. Both model analysis and experimental results are presented in detail in this presentation.

  19. Measurement of ultrasonic power and electro-acoustic efficiency of high power transducers.

    PubMed

    Lin, S; Zhang, F

    2000-01-01

    In this paper, an improved method for the measurement of acoustic power and electro-acoustic efficiency of high power ultrasonic transducers is presented. The measuring principle is described, the experimental results are given. In comparison with traditional methods, the method presented in this paper has the advantages of simplicity, economy and practicality. The most important is that it can measure the output acoustic power and the electro-acoustic efficiency of the transducer under the condition of high power and practical applications, such as ultrasonic cleaning and soldering.

  20. An Evaluation of the Additional Acoustic Power Needed to Overcome the Effects of a Test-Article's Absorption during Reverberant Chamber Acoustic Testing of Spaceflight Hardware

    NASA Technical Reports Server (NTRS)

    Hozman, Aron D.; Hughes, William O.

    2014-01-01

    The exposure of a customers aerospace test-article to a simulated acoustic launch environment is typically performed in a reverberant acoustic test chamber. The acoustic pre-test runs that will ensure that the sound pressure levels of this environment can indeed be met by a test facility are normally performed without a test-article dynamic simulator of representative acoustic absorption and size. If an acoustic test facilitys available acoustic power capability becomes maximized with the test-article installed during the actual test then the customers environment requirement may become compromised. In order to understand the risk of not achieving the customers in-tolerance spectrum requirement with the test-article installed, an acoustic power margin evaluation as a function of frequency may be performed by the test facility. The method for this evaluation of acoustic power will be discussed in this paper. This method was recently applied at the NASA Glenn Research Center Plum Brook Stations Reverberant Acoustic Test Facility for the SpaceX Falcon 9 Payload Fairing acoustic test program.

  1. An Evaluation of the Additional Acoustic Power Needed to Overcome the Effects of a Test-Article's Absorption During Reverberant Chamber Acoustic Testing of Spaceflight Hardware

    NASA Technical Reports Server (NTRS)

    Hozman, Aron D.; Hughes, William O.

    2014-01-01

    The exposure of a customer's aerospace test-article to a simulated acoustic launch environment is typically performed in a reverberant acoustic test chamber. The acoustic pre-test runs that will ensure that the sound pressure levels of this environment can indeed be met by a test facility are normally performed without a test-article dynamic simulator of representative acoustic absorption and size. If an acoustic test facility's available acoustic power capability becomes maximized with the test-article installed during the actual test then the customer's environment requirement may become compromised. In order to understand the risk of not achieving the customer's in-tolerance spectrum requirement with the test-article installed, an acoustic power margin evaluation as a function of frequency may be performed by the test facility. The method for this evaluation of acoustic power will be discussed in this paper. This method was recently applied at the NASA Glenn Research Center Plum Brook Station's Reverberant Acoustic Test Facility for the SpaceX Falcon 9 Payload Fairing acoustic test program.

  2. Design Report for Low Power Acoustic Detector

    DTIC Science & Technology

    2013-08-01

    the hardware design, target detection algorithm design in both MATLAB and VHDL , and typical performance results. 15. SUBJECT TERMS Acoustic low...diagram. .......................................................................................................3 Figure 4. HED VHDL block diagram...6 Figure 5. DCD VHDL block diagram

  3. Acoustical power amplification and damping by temperature gradients.

    PubMed

    Biwa, Tetsushi; Komatsu, Ryo; Yazaki, Taichi

    2011-01-01

    Ceperley proposed a concept of a traveling wave heat engine ["A pistonless Stirling engine-The traveling wave heat engine," J. Acoust. Soc. Am. 66, 1508-1513 (1979).] that provided a starting point of thermoacoustics today. This paper verifies experimentally his idea through observation of amplification and strong damping of a plane acoustic traveling wave as it passes through axial temperature gradients. The acoustic power gain is shown to obey a universal curve specified by a dimensionless parameter ωτα; ω is the angular frequency and τα is the relaxation time for the gas to thermally equilibrate with channel walls. As an application of his idea, a three-stage acoustic power amplifier is developed, which attains the gain up to 10 with a moderate temperature ratio of 2.3.

  4. 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.

  5. Acoustic and streaming velocity components in a resonant waveguide at high acoustic levels.

    PubMed

    Daru, Virginie; Reyt, Ida; Bailliet, Hélène; Weisman, Catherine; Baltean-Carlès, Diana

    2017-01-01

    Rayleigh streaming is a steady flow generated by the interaction between an acoustic wave and a solid wall, generally assumed to be second order in a Mach number expansion. Acoustic streaming is well known in the case of a stationary plane wave at low amplitude: it has a half-wavelength spatial periodicity and the maximum axial streaming velocity is a quadratic function of the acoustic velocity amplitude at antinode. For higher acoustic levels, additional streaming cells have been observed. Results of laser Doppler velocimetry measurements are here compared to direct numerical simulations. The evolution of axial and radial velocity components for both acoustic and streaming velocities is studied from low to high acoustic amplitudes. Two streaming flow regimes are pointed out, the axial streaming dependency on acoustics going from quadratic to linear. The evolution of streaming flow is different for outer cells and for inner cells. Also, the hypothesis of radial streaming velocity being of second order in a Mach number expansion, is not valid at high amplitudes. The change of regime occurs when the radial streaming velocity amplitude becomes larger than the radial acoustic velocity amplitude, high levels being therefore characterized by nonlinear interaction of the different velocity components.

  6. Acoustic Analog to Quantum Mechanical Level-Splitting

    NASA Astrophysics Data System (ADS)

    Hilbert, Shawn

    2010-03-01

    One difficulty in teaching quantum mechanics is the lack of classroom demonstrations. To sidestep this issue, analogies can provide an enlightening alternative. Acoustics governance by the same time-independent wave equation as quantum mechanics supports it use in such analogies. This presentation examines one such analogy for an infinite potential well with a delta potential perturbation. The physical acoustic system consists of continuous sounds waves traveling in a pair of tubes which are separated by a variable diaphragm. The level-splitting nature of the quantum system can be mimicked in the acoustic system.

  7. Ultrasonic level and temperature sensor for power reactor applications

    SciTech Connect

    Dress, W.B.: Miller, G.N.

    1983-01-01

    An ultrasonic waveguide employing torsional and extensional acoustic waves has been developed for use as a level and temperature sensor in pressurized and boiling water nuclear power reactors. Features of the device include continuous measurement of level, density, and temperature producing a real-time profile of these parameters along a chosen path through the reactor vessel.

  8. Sound pressure level gain in an acoustic metamaterial cavity.

    PubMed

    Song, Kyungjun; Kim, Kiwon; Hur, Shin; Kwak, Jun-Hyuk; Park, Jihyun; Yoon, Jong Rak; Kim, Jedo

    2014-12-11

    The inherent attenuation of a homogeneous viscous medium limits radiation propagation, thereby restricting the use of many high-frequency acoustic devices to only short-range applications. Here, we design and experimentally demonstrate an acoustic metamaterial localization cavity which is used for sound pressure level (SPL) gain using double coiled up space like structures thereby increasing the range of detection. This unique behavior occurs within a subwavelength cavity that is 1/10(th) of the wavelength of the incident acoustic wave, which provides up to a 13 dB SPL gain. We show that the amplification results from the Fabry-Perot resonance of the cavity, which has a simultaneously high effective refractive index and effective impedance. We also experimentally verify the SPL amplification in an underwater environment at higher frequencies using a sample with an identical unit cell size. The versatile scalability of the design shows promising applications in many areas, especially in acoustic imaging and underwater communication.

  9. Sound Pressure Level Gain in an Acoustic Metamaterial Cavity

    NASA Astrophysics Data System (ADS)

    Song, Kyungjun; Kim, Kiwon; Hur, Shin; Kwak, Jun-Hyuk; Park, Jihyun; Yoon, Jong Rak; Kim, Jedo

    2014-12-01

    The inherent attenuation of a homogeneous viscous medium limits radiation propagation, thereby restricting the use of many high-frequency acoustic devices to only short-range applications. Here, we design and experimentally demonstrate an acoustic metamaterial localization cavity which is used for sound pressure level (SPL) gain using double coiled up space like structures thereby increasing the range of detection. This unique behavior occurs within a subwavelength cavity that is 1/10th of the wavelength of the incident acoustic wave, which provides up to a 13 dB SPL gain. We show that the amplification results from the Fabry-Perot resonance of the cavity, which has a simultaneously high effective refractive index and effective impedance. We also experimentally verify the SPL amplification in an underwater environment at higher frequencies using a sample with an identical unit cell size. The versatile scalability of the design shows promising applications in many areas, especially in acoustic imaging and underwater communication.

  10. Sandia National Laboratories' new high level acoustic test facility

    SciTech Connect

    Rogers, J. D.; Hendrick, D. M.

    1989-01-01

    A high intensity acoustic test facility has been designed and is under construction at Sandia National Laboratories in Albuquerque, NM. The chamber is designed to provide an acoustic environment of 154dB (re 20 {mu}Pa) overall sound pressure level over the bandwidth of 50 Hz to 10,000 Hz. The chamber has a volume of 16,000 cubic feet with interior dimensions of 21.6 ft {times} 24.6 ft {times} 30 ft. The construction of the chamber should be complete by the summer of 1990. This paper discusses the design goals and constraints of the facility. The construction characteristics are discussed in detail, as are the acoustic performance design characteristics. The authors hope that this work will help others in designing acoustic chambers. 12 refs., 6 figs.

  11. Equal autophonic level curves under different room acoustics conditions.

    PubMed

    Pelegrín-García, David; Fuentes-Mendizábal, Oier; Brunskog, Jonas; Jeong, Cheol-Ho

    2011-07-01

    The indirect auditory feedback from one's own voice arises from sound reflections at the room boundaries or from sound reinforcement systems. The relative variations of indirect auditory feedback are quantified through room acoustic parameters such as the room gain and the voice support, rather than the reverberation time. Fourteen subjects matched the loudness level of their own voice (the autophonic level) to that of a constant and external reference sound, under different synthesized room acoustics conditions. The matching voice levels are used to build a set of equal autophonic level curves. These curves give an indication of the amount of variation in voice level induced by the acoustic environment as a consequence of the sidetone compensation or Lombard effect. In the range of typical rooms for speech, the variations in overall voice level that result in a constant autophonic level are on the order of 2 dB, and more than 3 dB in the 4 kHz octave band. By comparison of these curves with previous studies, it is shown that talkers use acoustic cues other than loudness to adjust their voices when speaking in different rooms.

  12. Power cepstrum technique with application to model helicopter acoustic data

    NASA Technical Reports Server (NTRS)

    Martin, R. M.; Burley, C. L.

    1986-01-01

    The application of the power cepstrum to measured helicopter-rotor acoustic data is investigated. A previously applied correction to the reconstructed spectrum is shown to be incorrect. For an exact echoed signal, the amplitude of the cepstrum echo spike at the delay time is linearly related to the echo relative amplitude in the time domain. If the measured spectrum is not entirely from the source signal, the cepstrum will not yield the desired echo characteristics and a cepstral aliasing may occur because of the effective sample rate in the frequency domain. The spectral analysis bandwidth must be less than one-half the echo ripple frequency or cepstral aliasing can occur. The power cepstrum editing technique is a useful tool for removing some of the contamination because of acoustic reflections from measured rotor acoustic spectra. The cepstrum editing yields an improved estimate of the free field spectrum, but the correction process is limited by the lack of accurate knowledge of the echo transfer function. An alternate procedure, which does not require cepstral editing, is proposed which allows the complete correction of a contaminated spectrum through use of both the transfer function and delay time of the echo process.

  13. Klamath Falls: High-Power Acoustic Well Stimulation Technology

    SciTech Connect

    Black, Brian

    2006-07-24

    Acoustic well stimulation (AWS) technology uses high-power sonic waves from specific frequency spectra in an attempt to stimulate production in a damaged or low-production wellbore. AWS technology is one of the most promising technologies in the oil and gas industry, but it has proven difficult for the industry to develop an effective downhole prototype. This collaboration between Klamath Falls Inc. and the Rocky Mountain Oilfield Testing Center (RMOTC) included a series of tests using high-power ultrasonic tools to stimulate oil and gas production. Phase I testing was designed and implemented to verify tool functionality, power requirements, and capacity of high-power AWS tools. The purpose of Phase II testing was to validate the production response of wells with marginal production rates to AWS stimulation and to capture and identify any changes in the downhole environment after tool deployment. This final report presents methodology and results.

  14. 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.

  15. Sound power and vibration levels for two different piano soundboards

    NASA Astrophysics Data System (ADS)

    Squicciarini, Giacomo; Valiente, Pablo Miranda; Thompson, David J.

    2016-09-01

    This paper compares the sound power and vibration levels for two different soundboards for upright pianos. One of them is made of laminated spruce and the other of solid spruce (tone-wood). These differ also in the number of ribs and manufacturing procedure. The methodology used is defined in two major steps: (i) acoustic power due to a unit force is obtained reciprocally by measuring the acceleration response of the piano soundboards when excited by acoustic waves in reverberant field; (ii) impact tests are adopted to measure driving point and spatially-averaged mean-square transfer mobility. The results show that, in the midhigh frequency range, the soundboard made of solid spruce has a greater vibrational and acoustic response than the laminated soundboard. The effect of string tension is also addressed, showing that is only relevant at low frequencies.

  16. A wireless acoustic emission sensor remotely powered by light

    NASA Astrophysics Data System (ADS)

    Zahedi, F.; Huang, H.

    2014-03-01

    In this paper, wireless sensing of acoustic emission (AE) signals using a battery-free sensor node remotely powered by light is presented. The wireless sensor consists of a piezoelectric wafer active sensor (PWAS) for AE signal acquisition and a wireless transponder that performs signal conditioning, frequency conversion, and wireless transmission. For signal conditioning, a voltage follower that consumes less than 2 mW was introduced to buffer the high impedance of the PWAS from the low impedance of the wireless transponder. A photocell-based energy harvester with a stable voltage output was developed to power the voltage follower so that the wireless AE sensor can operate without an external power source. The principle of operation of the battery-free wireless AE sensor node and the sensor interrogation system is described, followed by a detailed description of the hardware implementation. The voltage follower and the wireless channel were characterized by ultrasound pitch-catch and pencil lead break experiments.

  17. Acoustic power of a moving point source in a moving medium

    NASA Technical Reports Server (NTRS)

    Cole, J. E., III; Sarris, I. I.

    1976-01-01

    The acoustic power output of a moving point-mass source in an acoustic medium which is in uniform motion and infinite in extent is examined. The acoustic medium is considered to be a homogeneous fluid having both zero viscosity and zero thermal conductivity. Two expressions for the acoustic power output are obtained based on a different definition cited in the literature for the average energy-flux vector in an acoustic medium in uniform motion. The acoustic power output of the source is found by integrating the component of acoustic intensity vector in the radial direction over the surface of an infinitely long cylinder which is within the medium and encloses the line of motion of the source. One of the power expressions is found to give unreasonable results even though the flow is uniform.

  18. High Frequency Acoustic Propagation using Level Set Methods

    DTIC Science & Technology

    2007-01-01

    solution of the high frequency approximation to the wave equation. Traditional solutions to the Eikonal equation in high frequency acoustics are...curvature can be extracted at any point of the front from the level set function (provided the normal and curvature are well-defined at that point ), and... points per wavelength to resolve the wave). Ray tracing is therefore the current standard for high frequency propagation modeling. LSM may provide

  19. Use of existing standards to measure sound power levels of powered hand tools-necessary revisions

    NASA Astrophysics Data System (ADS)

    Hayden, Charles S.; Zechmann, Edward

    2005-09-01

    At recent NOISE-CON and Acoustical Society of America meetings, noise rating labeling was discussed as a way of manufacturers providing full disclosure information for their noise emitting products. The first step is to gather sound power level data from these products. Sound power level data should be gathered in accordance with existing ANSI and/or ISO standards. Some standards, such as ANSI 12.15, may not define true operational noise emissions[r1] and thus may provide inaccurate information when that information is used to choose a hearing protection device or used to make a purchasing decision. A number of standards were systematically combined by NIOSH researchers to provide the most accurate information on sound power levels of powered hand tools used in the construction industry. This presentation will detail some of the challenges of existing ANSI 12.15 (and draft ANSI 12.41) to measure sound power levels of electric (and pneumatic) powered hand tools.

  20. 2-D steering and propelling of acoustic bubble-powered microswimmers.

    PubMed

    Feng, Jian; Yuan, Junqi; Cho, Sung Kwon

    2016-06-21

    This paper describes bi-directional (linear and rotational) propelling and 2-D steering of acoustic bubble-powered microswimmers that are achieved in a centimeter-scale pool (beyond chip level scale). The core structure of a microswimmer is a microtube with one end open in which a gaseous bubble is trapped. The swimmer is propelled by microstreaming flows that are generated when the trapped bubble is oscillated by an external acoustic wave. The bubble oscillation and thus propelling force are highly dependent on the frequency of the acoustic wave and the bubble length. This dependence is experimentally studied by measuring the resonance behaviors of the testing pool and bubble using a laser Doppler vibrometer (LDV) and by evaluating the generated streaming flows. The key idea in the present 2-D steering is to utilize this dependence. Multiple bubbles with different lengths are mounted on a single microswimmer with a variety of arrangements. By controlling the frequency of the acoustic wave, only frequency-matched bubbles can strongly oscillate and generate strong propulsion. By arranging multiple bubbles of different lengths in parallel but with their openings opposite and switching the frequency of the acoustic wave, bi-directionally linear propelling motions are successfully achieved. The propelling forces are calculated by a CFD analysis using the Ansys Fluent® package. For bi-directional rotations, a similar method but with diagonal arrangement of bubbles on a rectangular swimmer is also applied. The rotation can be easily reversed when the frequency of the acoustic wave is switched. For 2-D steering, short bubbles are aligned perpendicular to long bubbles. It is successfully demonstrated that the microswimmer navigates through a T-junction channel under full control with and without carrying a payload. During the navigation, the frequency is the main control input to select and resonate targeted bubbles. All of these operations are achieved by a single

  1. Acoustic intensity near a high-powered military jet aircraft.

    PubMed

    Stout, Trevor A; Gee, Kent L; Neilsen, Tracianne B; Wall, Alan T; James, Michael M

    2015-07-01

    The spatial variation in vector acoustic intensity has been calculated between 100 and 3000 Hz near a high-performance military aircraft. With one engine of a tethered F-22A Raptor operating at military power, a tetrahedral intensity probe was moved to 27 locations in the geometric near and mid-fields to obtain the frequency-dependent intensity vector field. The angles of the maximum intensity region rotate from aft to sideline with increasing frequency, becoming less directional above 800 Hz. Between 100 and 400 Hz, which are principal radiation frequencies, the ray-traced dominant source region rapidly contracts and moves upstream, approaching nearly constant behavior by 1000 Hz.

  2. Design of fluid-loaded piezoelectric transducers for acoustic power considerations

    NASA Astrophysics Data System (ADS)

    Grosh, Karl; Lin, Yuan; Nelli Silva, Emilio C.; Kikuchi, Noboru

    1998-07-01

    In this paper, a design methodology for enhancing the acoustic power radiated from fluid-loaded piezoelectric transducers at a particular operating frequency is developed. For many applications the operating frequency is fixed by the absorption of the material and the desired depth of penetration (e.g., therapeutic ultrasound). For therapeutic ultrasound and other industrial applications, the acoustic power is the critical figure of merit. The acoustic power radiated from the transducer system is computed from a finite element formulation of the coupled acoustic, elastic, piezoelectric equations of motion. The sensitivities of the acoustic power to two design variables: the length of the piezoelectric element and the thickness of the matching layer, are derived. Using these sensitivities, a novel design methodology in which remeshing is avoided is developed and the effectiveness of the method is studied. Results from the application of this framework for transducer design demonstrate the dramatic increase in radiated power possible from this two member design space.

  3. Progress in Acoustic Transmission of Power through Walls

    NASA Technical Reports Server (NTRS)

    Sherrit,Stewart; Coty, Benjamin; Bao, Xiaoqi; Bar-Cohen, Yoseph; Badescu, Mircea; Chang, Zensheu

    2008-01-01

    A document presents updated information on implementation of the wireless acoustic-electric feed-through (WAEF) concept, which was reported in Using Piezoelectric Devices To Transmit Power Through Walls (NPO-41157), NASA Tech Briefs, Vol. 32, No. 6 (June 2008), page 70. To recapitulate: In a basic WAEF setup, a transmitting piezoelectric transducer on one side of a wall is driven at resonance to excite ultrasonic vibrations in the wall. A receiving piezoelectric transducer on the opposite side of the wall converts the vibrations back to an ultrasonic AC electric signal, which is then detected and otherwise processed in a manner that depends on the modulation (if any) applied to the signal and whether the signal is used to transmit power, data, or both. The present document expands upon the previous information concerning underlying physical principles, advantages, and potential applications of WAEF. It discusses the design and construction of breadboard prototype piezoelectric transducers for WAEF. It goes on to present results of computational simulations of performance and results of laboratory tests of the prototypes. In one notable test, a 100-W light bulb was lit by WAEF to demonstrate the feasibility of powering a realistic load.

  4. Moisture estimation in power transformer oil using acoustic signals and spectral kurtosis

    NASA Astrophysics Data System (ADS)

    Leite, Valéria C. M. N.; Veloso, Giscard F. C.; Borges da Silva, Luiz Eduardo; Lambert-Torres, Germano; Borges da Silva, Jonas G.; Onofre Pereira Pinto, João

    2016-03-01

    The aim of this paper is to present a new technique for estimating the contamination by moisture in power transformer insulating oil based on the spectral kurtosis analysis of the acoustic signals of partial discharges (PDs). Basically, in this approach, the spectral kurtosis of the PD acoustic signal is calculated and the correlation between its maximum value and the moisture percentage is explored to find a function that calculates the moisture percentage. The function can be easily implemented in DSP, FPGA, or any other type of embedded system for online moisture monitoring. To evaluate the proposed approach, an experiment is assembled with a piezoelectric sensor attached to a tank, which is filled with insulating oil samples contaminated by different levels of moisture. A device generating electrical discharges is submerged into the oil to simulate the occurrence of PDs. Detected acoustic signals are processed using fast kurtogram algorithm to extract spectral kurtosis values. The obtained data are used to find the fitting function that relates the water contamination to the maximum value of the spectral kurtosis. Experimental results show that the proposed method is suitable for online monitoring system of power transformers.

  5. 1KW Power Transmission Using Wireless Acoustic-Electric Feed-Through (WAEF)

    NASA Technical Reports Server (NTRS)

    Sherrit, S.; Bao, X.; Badescu, M.; Aldrich, J.; Bar-Cohen, Y.; Biederman, W.

    2008-01-01

    A variety of space applications require the delivery of power into sealed structures. Since the structural integrity can be degraded by holes for cabling we present an alternative method of delivering power and information using stress waves to the internal space of a sealed structure. One particular application of this technology is in sample return missions where it is critical to preserve the sample integrity and to prevent earth contamination. Therefore, the container has to be hermetically sealed and the integrity of the seal must be monitored in order to insure to a high degree of reliability the integrity of the sample return vessel. In this study we investigated the use of piezoelectric acoustic-electric power feed-through devices to transfer electric power wirelessly through a solid wall by using elastic or acoustic waves. The technology is applicable to a range of space and terrestrial applications where power is required by electronic equipment inside sealed containers, vacuum or pressure vessels, etc., where holes in the wall are prohibitive or may result in significant structural performance degradation or unnecessarily complex designs. To meet requirements of higher power applications, the feasibility to transfer kilowatts level power was investigated. Pre-stressed longitudinal piezoelectric feed-through devices were analyzed by finite element models and an equivalent circuit model was developed to predict the power transfer characteristics to different electric loads. Based on the results of the analysis a prototype device was designed, fabricated and a demonstration of the transmission of electric power up to 1.068-kW was successfully conducted. Efficiencies in the 80-90% range were also demonstrated and methods to increase the efficiency further are currently being considered.

  6. Acoustic power measurement of high intensity focused ultrasound in medicine based on radiation force.

    PubMed

    Shou, Wende; Huang, Xiaowei; Duan, Shimei; Xia, Rongmin; Shi, Zhonglong; Geng, Xiaoming; Li, Faqi

    2006-12-22

    How to measure the acoustic power of HIFU is one of the most important tasks in its medical application. In the paper a whole series of formula for calculating the radiation force related to the acoustic power radiated by a single element focusing transducer and by the focusing transducer array were given. Various system of radiation force balance (RFB) to measure the acoustic power of HIFU in medicine were designed and applied in China. In high power experiments, the dependence of radiation force acting the absorbing target on the target position at the beam axis of focusing transducer was fined. There is a peak value of "radiation force" acting the absorbing target in the focal region when the acoustic power through the focal plane exceeds some threshold. In order to avoid this big measurement error caused by the 'peak effect' in focal region, the distance between the absorbing target of RFB and the focusing transducer or transducer array was defined to be equal to or less than 0.7 times of the focal length in the National Standard of China for the measurements of acoustic power and field characteristics of HIFU. More than six different therapeutic equipments of HIFU have been examined by RFB for measuring the acoustic power since 1998. These results show that RFB with the absorbing target is valid in the acoustic power range up to 500W with good linearity for the drive voltage squared of focusing transducer or array. The uncertainty of measurement is within +/-15%.

  7. Structural Dynamic Assessment of the GN2 Piping System for NASA's New and Powerful Reverberant Acoustic Test Facility

    NASA Technical Reports Server (NTRS)

    McNelis, Mark E.; Staab, Lucas D.; Akers, James C.; Hughes, WIlliam O.; Chang, Li, C.; Hozman, Aron D.; Henry, Michael W.

    2012-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has led the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA from 2007-2011. SAIC-Benham has completed construction of a new reverberant acoustic test facility to support the future testing needs of NASA's space exploration program and commercial customers. The large Reverberant Acoustic Test Facility (RATF) is approximately 101,000 cu ft in volume and was designed to operate at a maximum empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world's known active reverberant acoustic test facilities. Initial checkout acoustic testing was performed on March 2011 by SAIC-Benham at test levels up to 161 dB OASPL. During testing, several branches of the gaseous nitrogen (GN2) piping system, which supply the fluid to the noise generating acoustic modulators, failed at their "t-junctions" connecting the 12 inch supply line to their respective 4 inch branch lines. The problem was initially detected when the oxygen sensors in the horn room indicated a lower than expected oxygen level from which was inferred GN2 leaks in the piping system. In subsequent follow up inspections, cracks were identified in the failed "t-junction" connections through non-destructive evaluation testing . Through structural dynamic modeling of the piping system, the root cause of the "t-junction" connection failures was determined. The structural dynamic assessment identified several possible corrective design improvements to the horn room piping system. The effectiveness of the chosen design repairs were subsequently evaluated in September 2011 during acoustic verification testing to 161 dB OASPL.

  8. Structural Dynamic Assessment of the GN2 Piping System for NASA's New and Powerful Reverberant Acoustic Test Facility

    NASA Technical Reports Server (NTRS)

    McNelis, Mark E.; Staab, Lucas D.; Akers, James C.; Hughes, William O.; Chang, Li C.; Hozman, Aron D.; Henry, Michael W.

    2012-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has led the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA from 2007 to 2011. SAIC-Benham has completed construction of a new reverberant acoustic test facility to support the future testing needs of NASA's space exploration program and commercial customers. The large Reverberant Acoustic Test Facility (RATF) is approximately 101,000 cubic feet in volume and was designed to operate at a maximum empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world s known active reverberant acoustic test facilities. Initial checkout acoustic testing was performed on March 2011 by SAIC-Benham at test levels up to 161 dB OASPL. During testing, several branches of the gaseous nitrogen (GN2) piping system, which supply the fluid to the noise generating acoustic modulators, failed at their T-junctions connecting the 12 in. supply line to their respective 4 in. branch lines. The problem was initially detected when the oxygen sensors in the horn room indicated a lower than expected oxygen level from which was inferred GN2 leaks in the piping system. In subsequent follow up inspections, cracks were identified in the failed T-junction connections through non-destructive evaluation testing. Through structural dynamic modeling of the piping system, the root cause of the T-junction connection failures was determined. The structural dynamic assessment identified several possible corrective design improvements to the horn room piping system. The effectiveness of the chosen design repairs were subsequently evaluated in September 2011 during acoustic verification testing to 161 dB OASPL.

  9. Acoustic power delivery to pipeline monitoring wireless sensors.

    PubMed

    Kiziroglou, M E; Boyle, D E; Wright, S W; Yeatman, E M

    2017-01-23

    The use of energy harvesting for powering wireless sensors is made more challenging in most applications by the requirement for customization to each specific application environment because of specificities of the available energy form, such as precise location, direction and motion frequency, as well as the temporal variation and unpredictability of the energy source. Wireless power transfer from dedicated sources can overcome these difficulties, and in this work, the use of targeted ultrasonic power transfer as a possible method for remote powering of sensor nodes is investigated. A powering system for pipeline monitoring sensors is described and studied experimentally, with a pair of identical, non-inertial piezoelectric transducers used at the transmitter and receiver. Power transmission of 18mW (Root-Mean-Square) through 1m of a118mm diameter cast iron pipe, with 8mm wall thickness is demonstrated. By analysis of the delay between transmission and reception, including reflections from the pipeline edges, a transmission speed of 1000m/s is observed, corresponding to the phase velocity of the L(0,1) axial and F(1,1) radial modes of the pipe structure. A reduction of power delivery with water-filling is observed, yet over 4mW of delivered power through a fully-filled pipe is demonstrated. The transmitted power and voltage levels exceed the requirements for efficient power management, including rectification at cold-starting conditions, and for the operation of low-power sensor nodes. The proposed powering technique may allow the implementation of energy autonomous wireless sensor systems for monitoring industrial and network pipeline infrastructure.

  10. Deepwater pipeline intervention work with an acoustically controlled power module

    SciTech Connect

    Conter, A.; Launaro, F.; Bigoni, G.

    1997-02-01

    The stabilization of submarine pipeline free spans along uneven sea bottoms is performed conventionally using technologies such as gravel dumping, post trenching, and mattress installation. A new technology has been developed to support free spans along the 26-inch Transmed Gas Pipelines crossing the Sicily Channel in water depths ranging from 50 m to 510 m. This technology is based on the pipeline mechanical support Atlantis and its installation module Pegaso and was developed keeping requirements such as short installation time, system redundancy, operational flexibility, and simple interface with the support vessel in mind. The installation time reduction is achieved by automatic operational procedures that are controlled acoustically from the surface. Power is stored inside two dedicated battery packs placed on board pegaso; no umbilical cable is necessary, so that a vessel equipped with a normal crane is enough to launch and operate the system. Marine operations carried out in 1993 showed that a support can be installed in about 1 hour. In good weather conditions, three Atlantis were installed in 24 hours, including deck operations for recharging the battery packs. A total of 16 supports was installed along the 4th and 5th Transmed Gas Pipelines. The system has proved to be a cost-effective and flexible alternative to conventional technologies for free-span support, especially in deep waters. A cost/benefit analysis also shows the break-even point of the new technology vs. gravel dumping.

  11. Acoustical performance of power plant enclosure walls-a critical assessment of needs

    NASA Astrophysics Data System (ADS)

    Putnam, Robert A.; Frederick, Noel

    2005-09-01

    The acoustical design of power generating facilities invariably requires knowledge of the transmission loss characteristics of acoustical enclosures, from component specific housings to generation buildings. Many of the composite wall configurations used by vendors are either proprietary or of such recent design that laboratory test data (TL per ASTM E90) are not available. Several factors contribute to uncertainty in the application of test data. At frequencies of 125 Hz and below, all such laboratory based test data should be considered suspect, especially since for plants in which sound emissions are heavily attenuated, the low frequencies tend to become progressively more dominant at far field positions. Thus the far field A-weighted sound levels from power plants, especially those of low noise design, are governed by sound energy in precisely the frequency range for which the TL's for walls and enclosures are least reliable. Further, the size and mounting of power plant walls differs significantly from the same walls mounted in an ASTM E90 test facility. This paper gives a critical assessment of the sources of the uncertainties, suggestions for methodologies to obtain more reliable TL data and discusses the effects to be expected, illustrated by way of selected examples.

  12. Mobility power flow analysis of coupled plate structure subjected to mechanical and acoustic excitation

    NASA Technical Reports Server (NTRS)

    Cuschieri, J. M.

    1992-01-01

    The mobility power flow approach that was previously applied in the derivation of expressions for the vibrational power flow between coupled plate substructures forming an L configuration and subjected to mechanical loading is generalized. Using the generalized expressions, both point and distributed mechanical loads on one or both of the plates can be considered. The generalized approach is extended to deal with acoustic excitation of one of the plate substructures. In this case, the forces (acoustic pressures) acting on the structure are dependent on the response of the structure because of the scattered pressure component. The interaction between the plate structure and the acoustic fluid leads to the derivation of a corrected mode shape for the plates' normal surface velocity and also for the structure mobility functions. The determination of the scattered pressure components in the expressions for the power flow represents an additional component in the power flow balance for the source plate and the receiver plate. This component represents the radiated acoustical power from the plate structure. For a number of coupled plate substrates, the acoustic pressure generated by one substructure will interact with the motion of another substructure. That is, in the case of the L-shaped plate, acoustic interaction exists between the two plate substructures due to the generation of the acoustic waves by each of the substructures. An approach to deal with this phenomena is described.

  13. Acoustic-loads research for powered-lift configurations

    NASA Technical Reports Server (NTRS)

    Schoenster, J. A.; Willis, C. M.; Schroeder, J. C.; Mixson, J. S.

    1976-01-01

    Data presented from large-scale model tests with jet engines having thrusts of 9 kN (2000 lb) and 36 kN (8000 lb) include acoustic loads for an externally blown wing and flap induced by a TF34 jet engine, an upper surface blown (USB) aircraft model in a wind tunnel, and two USB models in static tests. Comparisons of these results with results from acoustic loads studies on configurations of other sizes are made and the implications of these results on interior noise and acoustic fatigue are discussed.

  14. A review of acoustic power transfer for bio-medical implants

    NASA Astrophysics Data System (ADS)

    Basaeri, Hamid; Christensen, David B.; Roundy, Shad

    2016-12-01

    Bio-implantable devices have been used to perform therapeutic functions such as drug delivery or diagnostic monitoring of physiological parameters. Proper operation of these devices depends on the continuous reliable supply of power. A battery, which is the conventional method to supply energy, is problematic in many of these devices as it limits the lifetime of the implant or dominates the size. In order to power implantable devices, power transfer techniques have been implemented as an attractive alternative to batteries and have received significant research interest in recent years. Acoustic waves are increasingly being investigated as a method for delivering power through human skin and the human body. Acoustic power transfer (APT) has some advantages over other powering techniques such as inductive power transfer and mid range RF power transmission. These advantages include lower absorption in tissue, shorter wavelength enabling smaller transducers, and higher power intensity threshold for safe operation. This paper will cover the basic physics and modeling of APT and will review the current state of acoustic (or ultrasonic) power transfer for biomedical implants. As the sensing and computational elements for biomedical implants are becoming very small, we devote particular attention to the scaling of acoustic and alternative power transfer techniques. Finally, we present current issues and challenges related to the implementation of this technique for powering implantable devices.

  15. Determination of hydrocarbon levels in water via laser-induced acoustics wave

    NASA Astrophysics Data System (ADS)

    Bidin, Noriah; Hossenian, Raheleh; Duralim, Maisarah; Krishnan, Ganesan; Marsin, Faridah Mohd; Nughro, Waskito; Zainal, Jasman

    2016-04-01

    Hydrocarbon contamination in water is a major environmental concern in terms of foreseen collapse of the natural ecosystem. Hydrocarbon level in water was determined by generating acoustic wave via an innovative laser-induced breakdown in conjunction with high-speed photographic coupling with piezoelectric transducer to trace acoustic wave propagation. A Q-switched Nd:YAG (40 mJ) was focused in cuvette-filled hydrocarbon solution at various concentrations (0-2000 ppm) to induce optical breakdown, shock wave generation and later acoustic wave propagation. A nitro-dye (ND) laser (10 mJ) was used as a flash to illuminate and frozen the acoustic wave propagation. Lasers were synchronised using a digital delay generator. The image of acoustic waves was grabbed and recorded via charged couple device (CCD) video camera at the speed of 30 frames/second with the aid of Matrox software version 9. The optical delay (0.8-10.0 μs) between the acoustic wave formation and its frozen time is recorded through photodetectors. A piezo-electric transducer (PZT) was used to trace the acoustic wave (sound signal), which cascades to a digital oscilloscope. The acoustic speed is calculated from the ratio of acoustic wave radius (1-8 mm) and optical time delay. Acoustic wave speed is found to linearly increase with hydrocarbon concentrations. The acoustic signal generation at higher hydrocarbon levels in water is attributed to supplementary mass transfer and impact on the probe. Integrated high-speed photography with transducer detection system authenticated that the signals indeed emerged from the laser-induced acoustic wave instead of photothermal processes. It is established that the acoustic wave speed in water is used as a fingerprint to detect the hydrocarbon levels.

  16. Acoustic spectroscopy: A powerful analytical method for the pharmaceutical field?

    PubMed

    Bonacucina, Giulia; Perinelli, Diego R; Cespi, Marco; Casettari, Luca; Cossi, Riccardo; Blasi, Paolo; Palmieri, Giovanni F

    2016-04-30

    Acoustics is one of the emerging technologies developed to minimize processing, maximize quality and ensure the safety of pharmaceutical, food and chemical products. The operating principle of acoustic spectroscopy is the measurement of the ultrasound pulse intensity and phase after its propagation through a sample. The main goal of this technique is to characterise concentrated colloidal dispersions without dilution, in such a way as to be able to analyse non-transparent and even highly structured systems. This review presents the state of the art of ultrasound-based techniques in pharmaceutical pre-formulation and formulation steps, showing their potential, applicability and limits. It reports in a simplified version the theory behind acoustic spectroscopy, describes the most common equipment on the market, and finally overviews different studies performed on systems and materials used in the pharmaceutical or related fields.

  17. Experimental setup for measurement of acoustic power dissipation in lined ducts for higher order modes propagation with air mean-flow conditions.

    PubMed

    Ville, Jean-Michel; Foucart, Felix

    2003-10-01

    A flow duct acoustic facility was developed to measure liner efficiency in attenuating higher order acoustic duct modes propagation conditions with mean air flow. The method is based on measurement, upstream and downstream of a liner, of the acoustic power produced by a periodic source. Directly measured total or modal acoustic powers are deduced from the local measurement, in both cross sections, of acoustic pressure, axial acoustic particle velocity, and axial mean flow velocity which are supplied by a probe made of a microphone and a single hot film. In this paper, the equipment, signal processing, and the data treatment process of this facility are first described. Then, information on the accuracy of the methodology is provided by a validation test performed with a rigid wall duct section. Finally, the results of an experiment carried out with a locally reacting liner and a mean flow velocity of 20 m/s will be presented. Measurements of the main attenuation frequency and of the main total acoustic power dissipated agree with the values for which the liner was designed. These results point out the limitations of the method presented to sources with high-level periodic sounds to provide a sufficient signal-to-noise ratio, the noise being produced by fluctuations of the turbulent flow.

  18. Stabilized Acoustic Levitation of Dense Materials Using a High-Powered Siren

    NASA Technical Reports Server (NTRS)

    Gammell, P. M.; Croonquist, A.; Wang, T. G.

    1982-01-01

    Stabilized acoustic levitation and manipulation of dense (e.g., steel) objects of 1 cm diameter, using a high powered siren, was demonstrated in trials that investigated the harmonic content and spatial distribution of the acoustic field, as well as the effect of sample position and reflector geometries on the acoustic field. Although further optimization is possible, the most stable operation achieved is expected to be adequate for most containerless processing applications. Best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper one. Operation slightly below resonance enhances stability as this minimizes the second harmonic, which is suspected of being a particularly destabilizing influence.

  19. Stabilized acoustic levitation of dense materials using a high-powered siren

    NASA Astrophysics Data System (ADS)

    Gammell, P. M.; Croonquist, A.; Wang, T. G.

    1982-12-01

    Stabilized acoustic levitation and manipulation of dense (e.g., steel) objects of 1 cm diameter, using a high powered siren, was demonstrated in trials that investigated the harmonic content and spatial distribution of the acoustic field, as well as the effect of sample position and reflector geometries on the acoustic field. Although further optimization is possible, the most stable operation achieved is expected to be adequate for most containerless processing applications. Best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper one. Operation slightly below resonance enhances stability as this minimizes the second harmonic, which is suspected of being a particularly destabilizing influence.

  20. Acoustic power measurement of high-intensity focused ultrasound transducer using a pressure sensor.

    PubMed

    Zhou, Yufeng

    2015-03-01

    The acoustic power of high-intensity focused ultrasound (HIFU) is an important parameter that should be measured prior to each treatment to guarantee effective and safe outcomes. A new calibration technique was developed that involves estimating the pressure distribution, calculating the acoustic power using an underwater pressure blast sensor, and compensating the contribution of harmonics to the acoustic power. The output of a clinical extracorporeal HIFU system (center frequency of ~1 MHz, p+ = 2.5-57.2 MPa, p(-) = -1.8 to -13.9 MPa, I(SPPA) = 513-22,940 W/cm(2), -6 dB size of 1.6 × 10 mm: lateral × axial) was measured using this approach and then compared with that obtained using a radiation force balance. Similarities were found between each method at acoustic power ranging from 18.2 W to 912 W with an electrical-to-acoustic conversion efficiency of ~42%. The proposed method has advantages of low weight, smaller size, high sensitivity, quick response, high signal-to-noise ratio (especially at low power output), robust performance, and easy operation of HIFU exposimetry measurement.

  1. Acoustic agglomeration of power plant fly ash for environmental and hot gas cleanup

    SciTech Connect

    Reethof, G.; Koopmann, G.H.

    1989-12-01

    This two year research program has the objectives of completing the several investigations associated with the use of high intensity acoustic energy to agglomerate micron and submicron sized particles in fly ash aerosols in order to provide the necessary scientific knowledge and design criteria for the specification of technically and economically viable intermediate flue gas treatment of coal fired power plants. Goals are to further the understanding of certain fundamental processes by means of theoretical and experimental investigations to include this knowledge in an advanced computerized model of the agglomeration processes. Tests with the acoustic agglomeration facilities available in Penn State's new High Intensity Acoustic Laboratory were to be used to verify the results from the acoustic agglomeration simulations. Research work continued on high power, high efficiency sirens with special emphasis on the nonlinear acoustic phenomena and novel means of significantly increasing siren efficiency. A study was carried out to evaluate the economics of conventional coal fired power plant clean-up systems using acoustic agglomeration as an intermediate flue gas treatment. 154 refs., 152 figs., 30 tabs.

  2. Measurements of mean flow and acoustic power for a subsonic jet impinging normal to a large rigid surface

    NASA Technical Reports Server (NTRS)

    Schloth, A. P.

    1976-01-01

    An experimental study was made to measure the mean flow field and acoustic power of a subsonic jet impinging normal to a large rigid surface. A 6.25 cm diameter, circular cool air jet was used at heights of 20, 10, and 5 jet diameters above the surface. The jet exit Mach number was varied from 0.28 to 0.93. Impact and static pressure surveys were made in directions both axial and lateral to the jet axis and also parallel and perpendicular to the surface. Acoustic power was calculated from microphone measurements made during each test run using a diffuse field calibration for the test facility. Results indicate that the flow field for jet impingement is characterized mainly by a strong rise in static pressure in the impingement region near the surface and by boundary layer development in the wall jet region. Acoustic power measurements generally followed a U(8) law for both the free jet and jet impingement although there was some variation especially at high Mach number and for close impingement distances. Overall noise levels increased with decreasing jet-to-surface height. Normalized power spectra correlated well for all cases when the Strouhal number was greater than 0.2; the correlation was poor when the Strouhal number was low.

  3. A survey of acoustic conditions and noise levels in secondary school classrooms in England.

    PubMed

    Shield, Bridget; Conetta, Robert; Dockrell, Julie; Connolly, Daniel; Cox, Trevor; Mydlarz, Charles

    2015-01-01

    An acoustic survey of secondary schools in England has been undertaken. Room acoustic parameters and background noise levels were measured in 185 unoccupied spaces in 13 schools to provide information on the typical acoustic environment of secondary schools. The unoccupied acoustic and noise data were correlated with various physical characteristics of the spaces. Room height and the amount of glazing were related to the unoccupied reverberation time and therefore need to be controlled to reduce reverberation to suitable levels for teaching and learning. Further analysis of the unoccupied data showed that the introduction of legislation relating to school acoustics in England and Wales in 2003 approximately doubled the number of school spaces complying with current standards. Noise levels were also measured during 274 lessons to examine typical levels generated during teaching activities in secondary schools and to investigate the influence of acoustic design on working noise levels in the classroom. Comparison of unoccupied and occupied data showed that unoccupied acoustic conditions affect the noise levels occurring during lessons. They were also related to the time spent in disruption to the lessons (e.g., students talking or shouting) and so may also have an impact upon student behavior in the classroom.

  4. Effects of voice style, noise level, and acoustic feedback on objective and subjective voice evaluations

    PubMed Central

    Bottalico, Pasquale; Graetzer, Simone; Hunter, Eric J.

    2015-01-01

    Speakers adjust their vocal effort when communicating in different room acoustic and noise conditions and when instructed to speak at different volumes. The present paper reports on the effects of voice style, noise level, and acoustic feedback on vocal effort, evaluated as sound pressure level, and self-reported vocal fatigue, comfort, and control. Speakers increased their level in the presence of babble and when instructed to talk in a loud style, and lowered it when acoustic feedback was increased and when talking in a soft style. Self-reported responses indicated a preference for the normal style without babble noise. PMID:26723357

  5. Acoustic agglomeration of power plant fly ash: Quarterly technical report, November 5, 1986--February 5, 1987

    SciTech Connect

    Reethof, G.

    1987-03-20

    The objective of this project is to complete the investigations on the use of high intensity acoustic energy to agglomerate micron and submicron sized particulates in fly ash aerosols in order to provide the necessary scientific knowledge and design criteria for the specification of technically and economically viable intermediate flue gas treatment of coal fired power plants. The results of the project are to provide technical and economic information for the better development and evaluation of potential fine particulate control systems. The goals of the proposed work are to further the understanding of certain fundamental processes by means of theoretical and experimental investigations, to include this knowledge in an advanced computerized model of the agglomeration processes. Tests with the two acoustic agglomerators available in Penn State's new High Intensity Acoustics Laboratory will be used to verify the results from the agglomeration simulation. Research work will continue on high power, high efficiency sirens with special emphasis on the nonlinear acoustic phenomena and novel means of significantly increasing siren efficiency. A study will be carried out to evaluate the economics of conventional coal fired power plant clean-up systems using acoustic agglomerators as intermediate flue gas treatment.

  6. An Evaluation of the Additional Acoustic Power Needed to Overcome the Effects of a Test-Articles Absorption During Reverberant Chamber Acoustic Testing of Spaceflight Hardware

    NASA Technical Reports Server (NTRS)

    Hozman, Aron D.; Hughes, William O.

    2014-01-01

    It is important to realize that some test-articles may have significant sound absorption that may challenge the acoustic power capabilities of a test facility. Therefore, to mitigate this risk of not being able to meet the customers target spectrum, it is prudent to demonstrate early-on an increased acoustic power capability which compensates for this test-article absorption. This paper describes a concise method to reduce this risk when testing aerospace test-articles which have significant absorption. This method was successfully applied during the SpaceX Falcon 9 Payload Fairing acoustic test program at the NASA Glenn Research Center Plum Brook Stations RATF.

  7. Singing whales generate high levels of particle motion: implications for acoustic communication and hearing?

    PubMed

    Mooney, T Aran; Kaplan, Maxwell B; Lammers, Marc O

    2016-11-01

    Acoustic signals are fundamental to animal communication, and cetaceans are often considered bioacoustic specialists. Nearly all studies of their acoustic communication focus on sound pressure measurements, overlooking the particle motion components of their communication signals. Here we characterized the levels of acoustic particle velocity (and pressure) of song produced by humpback whales. We demonstrate that whales generate acoustic fields that include significant particle velocity components that are detectable over relatively long distances sufficient to play a role in acoustic communication. We show that these signals attenuate predictably in a manner similar to pressure and that direct particle velocity measurements can provide bearings to singing whales. Whales could potentially use such information to determine the distance of signalling animals. Additionally, the vibratory nature of particle velocity may stimulate bone conduction, a hearing modality found in other low-frequency specialized mammals, offering a parsimonious mechanism of acoustic energy transduction into the massive ossicles of whale ears. With substantial concerns regarding the effects of increasing anthropogenic ocean noise and major uncertainties surrounding mysticete hearing, these results highlight both an unexplored pathway that may be available for whale acoustic communication and the need to better understand the biological role of acoustic particle motion.

  8. Solar cycle variations in the powers and damping rates of low-degree solar acoustic oscillations

    NASA Astrophysics Data System (ADS)

    Broomhall, A.-M.; Pugh, C. E.; Nakariakov, V. M.

    2015-12-01

    Helioseismology uses the Sun's natural resonant oscillations to study the solar interior. The properties of the solar oscillations are sensitive to the Sun'2019;s magnetic activity cycle. Here we examine variations in the powers, damping rates, and energy supply rates of the most prominent acoustic oscillations in unresolved, Sun-as-a-star data, obtained by the Birmingham Solar Oscillations Network (BiSON) during solar cycles 22, 23, and the first half of 24. The variations in the helioseismic parameters are compared to the 10.7 cm flux, a well-known global proxy of solar activity. As expected the oscillations are most heavily damped and the mode powers are at a minimum at solar activity maximum. The 10.7 cm flux was linearly regressed using the fractional variations of damping rates and powers observed during cycle 23. In general, good agreement is found between the damping rates and the 10.7 cm flux. However, the linearly regressed 10.7 cm flux and fractional variation in powers diverge in cycles 22 and 24, indicating that the relationship between the mode powers and the 10.7 cm flux is not consistent from one cycle to the next. The energy supply rate of the oscillations, which is usually approximately constant, also decreases at this time. We have determined that this discrepancy is not because of the first-order bias introduced by an increase in the level of background noise or gaps in the data. Although we cannot categorically rule out an instrumental origin, the divergence observed in cycle 24, when the data were of high quality and the data coverage was over 80%, raises the possibility that the effect may be solar in origin.

  9. Sound radiation from single and annular stream nozzles, with modal decomposition of in-duct acoustic power

    NASA Technical Reports Server (NTRS)

    Salikuddin, M.

    1987-01-01

    An experimental program was carried out to study the acoustic characteristics of single and annular stream duct-nozzle systems at various flow conditions by using a refined acoustic impulse technique. In this technique, signal synthesis and signal averaging processes are incorporated to generate a desired impulsive signal from acoustic driver(s) and to eliminate background noise (flow noise) from in-duct and far field signals, respectively. The contribution of higher order modes to incident reflected and transmitted acoustic powers is accounted for by using a modal decomposition process. The annular stream terminations were tested statically at various annular stream flow velocities with no inner stream flow. The results derived from the experiments include in-duct acoustic powers, termination reflection coefficients, transmission coefficients, far field power, and acoustic dissipation.

  10. Ultrasound imparted air-recoil resonance (UIAR) method for acoustic power estimation: theory and experiment.

    PubMed

    Kaiplavil, Sreekumar; Rivens, Ian; ter Haar, Gail

    2013-07-01

    Ultrasound imparted air-recoil resonance (UIAR), a new method for acoustic power estimation, is introduced with emphasis on therapeutic high-intensity focused ultrasound (HIFU) monitoring applications. Advantages of this approach over existing practices include fast response; electrical and magnetic inertness, and hence MRI compatibility; portability; high damage threshold and immunity to vibration and interference; low cost; etc. The angle of incidence should be fixed for accurate measurement. However, the transducer-detector pair can be aligned in any direction with respect to the force of gravity. In this sense, the operation of the device is orientation independent. The acoustic response of a pneumatically coupled pair of Helmholtz resonators, with one of them acting as the sensor head, is used for the estimation of acoustic power. The principle is valid in the case of pulsed/ burst as well as continuous ultrasound exposure, the former being more sensitive and accurate. An electro-acoustic theory has been developed for describing the dynamics of pressure flow and resonance in the system considering various thermo- viscous loss mechanisms. Experimental observations are found to be in agreement with theoretical results. Assuming the window damage threshold (~10 J·mm(-2)) and accuracy of RF power estimation are the upper and lower scale-limiting factors, the performance of the device was examined for an RF power range of 5 mW to 100 W with a HIFU transducer operating at 1.70 MHz, and an average nonlinearity of ~1.5% was observed. The device is also sensitive to sub-milliwatt powers. The frequency response was analyzed at 0.85, 1.70, 2.55, and 3.40 MHz and the results are presented with respective theoretical estimates. Typical response time is in the millisecond regime. Output drift is about 3% for resonant and 5% for nonresonant modes. The principle has been optimized to demonstrate a general-purpose acoustic power meter.

  11. School cafeteria noise-The impact of room acoustics and speech intelligibility on children's voice levels

    NASA Astrophysics Data System (ADS)

    Bridger, Joseph F.

    2002-05-01

    The impact of room acoustics and speech intelligibility conditions of different school cafeterias on the voice levels of children is examined. Methods of evaluating cafeteria designs and predicting noise levels are discussed. Children are shown to modify their voice levels with changes in speech intelligibility like adults. Reverberation and signal to noise ratio are the important acoustical factors affecting speech intelligibility. Children have much more difficulty than adults in conditions where noise and reverberation are present. To evaluate the relationship of voice level and speech intelligibility, a database of real sound levels and room acoustics data was generated from measurements and data recorded during visits to a variety of existing cafeterias under different occupancy conditions. The effects of speech intelligibility and room acoustics on childrens voice levels are demonstrated. A new method is presented for predicting speech intelligibility conditions and resulting noise levels for the design of new cafeterias and renovation of existing facilities. Measurements are provided for an existing school cafeteria before and after new room acoustics treatments were added. This will be helpful for acousticians, architects, school systems, regulatory agencies, and Parent Teacher Associations to create less noisy cafeteria environments.

  12. Comparison of Comet Enflow and VA One Acoustic-to-Structure Power Flow Predictions

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.; Schiller, Noah H.; Cabell, Randolph H.

    2010-01-01

    Comet Enflow is a commercially available, high frequency vibroacoustic analysis software based on the Energy Finite Element Analysis (EFEA). In this method the same finite element mesh used for structural and acoustic analysis can be employed for the high frequency solutions. Comet Enflow is being validated for a floor-equipped composite cylinder by comparing the EFEA vibroacoustic response predictions with Statistical Energy Analysis (SEA) results from the commercial software program VA One from ESI Group. Early in this program a number of discrepancies became apparent in the Enflow predicted response for the power flow from an acoustic space to a structural subsystem. The power flow anomalies were studied for a simple cubic, a rectangular and a cylindrical structural model connected to an acoustic cavity. The current investigation focuses on three specific discrepancies between the Comet Enflow and the VA One predictions: the Enflow power transmission coefficient relative to the VA One coupling loss factor; the importance of the accuracy of the acoustic modal density formulation used within Enflow; and the recommended use of fast solvers in Comet Enflow. The frequency region of interest for this study covers the one-third octave bands with center frequencies from 16 Hz to 4000 Hz.

  13. Relationship between acoustic power and acoustic radiation force on absorbing and reflecting targets for spherically focusing radiators.

    PubMed

    Gélat, Pierre; Shaw, Adam

    2015-03-01

    Total acoustic output power is an important parameter required by standards for most ultrasonic medical equipment including high-intensity focused ultrasound (HIFU) systems. Radiation force balances are routinely used; however, radiation force is not strictly dependent on the ultrasound power but, rather, on the wave momentum resolved in one direction. Consequently, measurements based on radiation force become progressively less accurate as the ultrasound wave deviates further from a true plane wave. HIFU transducers can be very strongly focused with F-numbers less than one: under these conditions, the uncertainty associated with use of the radiation force method becomes very significant. International Standards IEC 61161 and IEC 62555 suggest plane-wave correction factors for unfocused transducers radiating onto an ideal absorbing target and focusing corrections for focused transducers radiating onto ideal absorbing targets and onto conical reflecting targets (IEC 61161). Previous models have relied on calculations based on the Rayleigh integral, which is not strictly correct for curved sources. In the work described here, an approach combining finite element methods with a discretization of the Helmholtz equation was developed, making it possible to model the boundary condition at the structure/fluid interface more correctly. This has been used to calculate the relationship between radiation force and total power for both absorbing and conical reflecting targets for transducers ranging from planar to an F-number of 0.5 (hemispherical) and to compare with the recommendations of IEC 61161 and IEC 62555.

  14. The Effect of the 226-Hz Probe Level on Contralateral Acoustic Stapedius Reflex Thresholds

    ERIC Educational Resources Information Center

    Day, Jessica E.; Feeney, M. Patrick

    2008-01-01

    Purpose: The purpose of this study was to examine the effect of the 226-Hz probe level on the acoustic stapedius reflex threshold. Method: Contralateral reflex thresholds for a 1000-Hz pure-tone stimulus were obtained from 40 young adults with normal hearing using an experimental system at four 226-Hz probe levels (70, 75, 80, and 85 dB SPL) with…

  15. Thermometric- and Acoustic-Based Beam Power Monitor for Ultra-Bright X-Rays

    SciTech Connect

    Bentsen, Gregory; /Rochester U. /SLAC

    2010-08-25

    A design for an average beam power monitor for ultra-bright X-ray sources is proposed that makes simultaneous use of calorimetry and radiation acoustics. Radiation incident on a solid target will induce heating and ultrasonic vibrations, both of which may be measured to give a fairly precise value of the beam power. The monitor is intended for measuring ultra-bright Free-Electron Laser (FEL) X-ray beams, for which traditional monitoring technologies such as photo-diodes or scintillators are unsuitable. The monitor consists of a Boron Carbide (B{sub 4}C) target designed to absorb most of the incident beam's energy. Resistance temperature detectors (RTD) and piezoelectric actuators are mounted on the outward faces of the target to measure the temperature changes and ultrasonic vibrations induced by the incident beam. The design was tested using an optical pulsed beam (780 nm, 120 and 360 Hz) from a Ti:sapphire oscillator at several energies between 0.8 and 2.6 mJ. The RTDs measured an increase in temperature of about 10 K over a period of several minutes. The piezoelectric sensors recorded ringing acoustic oscillations at 580 {+-} 40 kHz. Most importantly, the amplitude of the acoustic signals was observed to scale linearly with beam power up to 2 mJ of pulse energy. Above this pulse energy, the vibrational signals became nonlinear. Several causes for this nonlinearity are discussed, including amplifier saturation and piezoelectric saturation. Despite this nonlinearity, these measurements demonstrate the feasibility of such a beam power measurement device. The advantage of two distinct measurements (acoustic and thermometric) provides a useful method of calibration that is unavailable to current LCLS diagnostics tools.

  16. Acoustic Power Suppression of a Panel Structure Using H∞OUTPUT Feedback Control

    NASA Astrophysics Data System (ADS)

    SIVRIOGLU, S.; TANAKA, N.; YUKSEK, I.

    2002-01-01

    This paper presents a robust control system design for suppressing the radiated acoustic power emitted from a vibrating planar structure, and spillover effect caused by neglected high-frequency modes. A state-space model of a simply supported panel structure is derived and an output equation is formed based on the one-dimensional PVDF film sensors. An output feedback H∞control is designed by introducing a multiplicative perturbation which represents unmodelled high-frequency dynamics in the control system. The simulation and experimental results demonstrated significant decrease in sound radiation for the considered structural power modes in control.

  17. Nonlinear behavior of electric power transmission through an elastic wall by acoustic waves and piezoelectric transducers.

    PubMed

    Yang, Zengtao; Yang, Jiashi; Hu, Yuantai

    2008-11-01

    Weakly nonlinear behavior of electric power transmission through an elastic wall by piezoelectric transducers and acoustic waves near resonance is studied based on the cubic theory of nonlinear electroelasticity. An approximate analytical solution is obtained. Output voltage is calculated and plotted. Basic nonlinear behaviors of the power transmission structure are examined. It is found that near nonlinear resonance the electrical input-output relation loses its linearity, becomes multi-valued, and experiences jumps due to large mechanical deformations. The behavior below and above resonance is qualitatively different and is qualitatively material dependent.

  18. Load influence on gear noise. [mathematical model for determining acoustic pressure level as function of load

    NASA Technical Reports Server (NTRS)

    Merticaru, V.

    1974-01-01

    An original mathematical model is proposed to derive equations for calculation of gear noise. These equations permit the acoustic pressure level to be determined as a function of load. Application of this method to three parallel gears is reported. The logical calculation scheme is given, as well as the results obtained.

  19. Amplification of interaural level differences improves sound localization in acoustic simulations of bimodal hearing.

    PubMed

    Francart, Tom; Van den Bogaert, Tim; Moonen, Marc; Wouters, Jan

    2009-12-01

    Users of a cochlear implant and contralateral hearing aid are sensitive to interaural level differences (ILDs). However, when using their clinical devices, most of these subjects cannot use ILD cues for localization in the horizontal plane. This is partly due to a lack of high-frequency residual hearing in the acoustically stimulated ear. Using acoustic simulations of a cochlear implant and hearing loss, it is shown that localization performance can be improved by up to 14 degrees rms error relative to 48 degrees rms error for broadband noise by artificially introducing ILD cues in the low frequencies. The algorithm that was used for ILD introduction is described.

  20. Fatigue Level Estimation of Bill Based on Acoustic Signal Feature by Supervised SOM

    NASA Astrophysics Data System (ADS)

    Teranishi, Masaru; Omatu, Sigeru; Kosaka, Toshihisa

    Fatigued bills have harmful influence on daily operation of Automated Teller Machine(ATM). To make the fatigued bills classification more efficient, development of an automatic fatigued bill classification method is desired. We propose a new method to estimate bending rigidity of bill from acoustic signal feature of banking machines. The estimated bending rigidities are used as continuous fatigue level for classification of fatigued bill. By using the supervised Self-Organizing Map(supervised SOM), we estimate the bending rigidity from only the acoustic energy pattern effectively. The experimental result with real bill samples shows the effectiveness of the proposed method.

  1. Unveiling acoustic physics of the CMB using nonparametric estimation of the temperature angular power spectrum for Planck

    SciTech Connect

    Aghamousa, Amir; Shafieloo, Arman; Arjunwadkar, Mihir; Souradeep, Tarun E-mail: shafieloo@kasi.re.kr E-mail: tarun@iucaa.ernet.in

    2015-02-01

    Estimation of the angular power spectrum is one of the important steps in Cosmic Microwave Background (CMB) data analysis. Here, we present a nonparametric estimate of the temperature angular power spectrum for the Planck 2013 CMB data. The method implemented in this work is model-independent, and allows the data, rather than the model, to dictate the fit. Since one of the main targets of our analysis is to test the consistency of the ΛCDM model with Planck 2013 data, we use the nuisance parameters associated with the best-fit ΛCDM angular power spectrum to remove foreground contributions from the data at multipoles ℓ ≥50. We thus obtain a combined angular power spectrum data set together with the full covariance matrix, appropriately weighted over frequency channels. Our subsequent nonparametric analysis resolves six peaks (and five dips) up to ℓ ∼1850 in the temperature angular power spectrum. We present uncertainties in the peak/dip locations and heights at the 95% confidence level. We further show how these reflect the harmonicity of acoustic peaks, and can be used for acoustic scale estimation. Based on this nonparametric formalism, we found the best-fit ΛCDM model to be at 36% confidence distance from the center of the nonparametric confidence set—this is considerably larger than the confidence distance (9%) derived earlier from a similar analysis of the WMAP 7-year data. Another interesting result of our analysis is that at low multipoles, the Planck data do not suggest any upturn, contrary to the expectation based on the integrated Sachs-Wolfe contribution in the best-fit ΛCDM cosmology.

  2. A series expansion of the acoustic power radiated from planar sources

    NASA Technical Reports Server (NTRS)

    Willams, E. G.

    1983-01-01

    A series expansion in ascending powers of the wavenumber k is derived for the acoustic power delivered by baffled or unbaffled planar sources. This series provides a relatively simple means of derving expressions for the power radiated by a baffled source with a known velocity distribution and can be used for unbaffled plates when the velocity field outside the plate is also known. The terms in the series are calculated from the moments of this velocity distribution in the plane containing the source. If these moments are written as derivaties in wavenumber space, it is shown that a MacLaurin expansion of the Fourier transformed velocity provides an easy technique for computing the first few terms of the acoustic power. Examples are provided for baffled, rectangular plates with various boundary conditions. The arbirarily shaped plate with free boundaries is particularly interesting. It is proven that the volume flow across it surface must be zero and as a result corner and edge mode radiation cannot exist for this kind of source.

  3. DC-9/JT8D refan, Phase 1. [technical and economic feasibility of retrofitting DC-9 aircraft with refan engine to achieve desired acoustic levels

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Analyses and design studies were conducted on the technical and economic feasibility of installing the JT8D-109 refan engine on the DC-9 aircraft. Design criteria included minimum change to the airframe to achieve desired acoustic levels. Several acoustic configurations were studied with two selected for detailed investigations. The minimum selected acoustic treatment configuration results in an estimated aircraft weight increase of 608 kg (1,342 lb) and the maximum selected acoustic treatment configuration results in an estimated aircraft weight increase of 809 kg (1,784 lb). The range loss for the minimum and maximum selected acoustic treatment configurations based on long range cruise at 10 668 m (35,000 ft) altitude with a typical payload of 6 804 kg (15,000 lb) amounts to 54 km (86 n. mi.) respectively. Estimated reduction in EPNL's for minimum selected treatment show 8 EPNdB at approach, 12 EPNdB for takeoff with power cutback, 15 EPNdB for takeoff without power cutback and 12 EPNdB for sideline using FAR Part 36. Little difference was estimated in EPNL between minimum and maximum treatments due to reduced performance of maximum treatment. No major technical problems were encountered in the study. The refan concept for the DC-9 appears technically feasible and economically viable at approximately $1,000,000 per airplane. An additional study of the installation of JT3D-9 refan engine on the DC-8-50/61 and DC-8-62/63 aircraft is included. Three levels of acoustic treatment were suggested for DC-8-50/61 and two levels for DC-8-62/63. Results indicate the DC-8 technically can be retrofitted with refan engines for approximately $2,500,000 per airplane.

  4. Aircraft IR/acoustic detection evaluation. Volume 2: Development of a ground-based acoustic sensor system for the detection of subsonic jet-powered aircraft

    NASA Technical Reports Server (NTRS)

    Kraft, Robert E.

    1992-01-01

    The design and performance of a ground-based acoustic sensor system for the detection of subsonic jet-powered aircraft is described and specified. The acoustic detection system performance criteria will subsequently be used to determine target detection ranges for the subject contract. Although the defined system has never been built and demonstrated in the field, the design parameters were chosen on the basis of achievable technology and overall system practicality. Areas where additional information is needed to substantiate the design are identified.

  5. Determination of an acoustic reflection coefficient at the inlet of a model gas turbine combustor for power generation

    NASA Astrophysics Data System (ADS)

    Song, W. J.; Cha, D. J.

    2017-01-01

    A phenomenon that potentially influences the reliability of power generation systems is the presence of thermo-acoustic oscillations in the combustion chamber of a land- based gas turbine. To develop specific measures that prevent the instability, it is essential to predict and/or evaluate the underlying physics of the thermo-acoustics, which requires the acoustic boundary condition at the exit of the burner, that is, at the inlet of the combustor. Here we report a procedure for calculating acoustic reflection coefficients at the burner exit by utilizing two microphone method (TMM) for dynamic pressure signals. The procedure has been verified by comparing its results with reported ones and further successfully employed to determine the acoustic boundary condition of the burner of a partially-premixed model gas turbine combustor.

  6. Features of Propagation of the Acoustic-Gravity Waves Generated by High-Power Periodic Radiation

    NASA Astrophysics Data System (ADS)

    Chernogor, L. F.; Frolov, V. L.

    2013-09-01

    We present the results of the bandpass filtering of temporal variations of the Doppler frequency shift of radio signals from a vertical-sounding Doppler radar located near the city of Kharkov when the ionosphere was heated by high-power periodic (with 10 and 15-min periods) radiation from the Sura facility. The filtering was done in the ranges of periods that are close to the acoustic cutoff period and the Brunt—Väisälä period (4-6, 8-12, and 13-17 min). Oscillations with periods of 4-6 min and amplitudes of 50-100 mHz were not recorded in fact. Oscillations with periods of 8-12 and 13-17 min and amplitudes of 60-100 mHz were detected in almost all the sessions. In the former and the latter oscillations, the time of delay with respect to the heater switch-on was close to 100 min and about 40-50 min, respectively. These values correspond to group propagation velocities of about 160 and 320-400 m/s. The Doppler shift oscillations were caused by the acoustic-gravity waves which led to periodic variations in the electron number density with a relative amplitude of about 0.1-1.0%. It was demonstrated that the acoustic-gravity waves were not recorded when the effective power of the Sura facility was equal to 50 MW and they were confidently observed when the effective power was increased up to 130 MW. It is shown that the period of the wave processes was determined by the period of the heating-pause cycles, and the duration of the wave trains did not depend on the duration of the series of heating-pause cycles. The data suggest that the generation mechanism of recorded wave disturbances is different from the mechanism proposed in 1970-1990.

  7. A detector for monitoring the onset of cavitation during therapy-level measurements of ultrasonic power

    NASA Astrophysics Data System (ADS)

    Hodnett, M.; Zeqiri, B.

    2004-01-01

    Acoustic cavitation occurring in the water path between a transducer and the target of a radiation force balance can provide a significant source of error during measurements of ultrasonic power. These problems can be particularly acute at physiotherapy levels (>1 W), and low frequencies (leq 1 MHz). The cavitating bubbles can absorb and scatter incident ultrasound, leading to an underestimate in the measured power. For these reasons, International Specification standards demand the use of degassed water. This imposes requirements that may actually be difficult to meet, for example, in the case of hospitals. Also, initially degassed water will rapidly re-gas, increasing the likelihood of cavitation occurring. For these reasons, NPL has developed a device that monitors acoustic emissions generated by bubble activity, for detecting the onset of cavitation during power measurements. A commercially available needle hydrophone is used to detect these emissions. The acoustic signals are then monitored using a Cavitation Detector (CD) unit, comprising an analogue electrical filter that may be tuned to detect frequency components generated by cavitating bubbles, and which provides an indication of when the measured level exceeds a pre-defined threshold. This paper describes studies to establish a suitable detection scheme, the principles of operation of the CD unit, and the performance tests carried out with a range of propagation media.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    SciTech Connect

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

    2015-03-14

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

  10. Assessing Acoustic Sound Levels Associated with Active Source Seismic Surveys in Shallow Marine Environments

    NASA Astrophysics Data System (ADS)

    Bohnenstiehl, D. R.; Tolstoy, M.; Thode, A.; Diebold, J. B.; Webb, S. C.

    2004-12-01

    The potential effect of active source seismic research on marine mammal populations is a topic of increasing concern, and controversy surrounding such operations has begun to impact the planning and permitting of academic surveys [e.g., Malakoff, 2002 Science]. Although no causal relationship between marine mammal strandings and seismic exploration has been proven, any circumstantial evidence must be thoroughly investigated. A 2002 stranding of two beaked whales in the Gulf of California within 50 km of a R/V Ewing seismic survey has been a subject of concern for both marine seismologists and environmentalists. In order to better understand possible received levels for whales in the vicinity of these operations, modeling is combined with ground-truth calibration measurements. A wide-angle parabolic equation model, which is capable of including shear within the sediment and basement layers, is used to generate predictive models of low-frequency transmission loss within the Gulf of California. This work incorporates range-dependent bathymetry, sediment thickness, sound velocity structure and sub-bottom properties. Oceanic sounds speed profiles are derived from the U.S. Navy's seasonal GDEM model and sediment thicknesses are taken from NOAA's worldwide database. The spectral content of the Ewing's 20-airgun seismic array is constrained by field calibration in the spring of 2003 [Tolstoy et al., 2004 GRL], indicating peak energies at frequencies below a few hundred Hz, with energy spectral density showing an approximate power-law decrease at higher frequencies (being ~40 dB below peak at 1 kHz). Transmission loss is estimated along a series of radials extending from multiple positions along the ship's track, with the directivity of the array accounted for by phase-shifting point sources that are scaled by the cube root of the individual airgun volumes. This allows the time-space history of low-frequency received levels to be reconstructed within the Gulf of California

  11. Numerical simulation of the processes in the normal incidence tube for high acoustic pressure levels

    NASA Astrophysics Data System (ADS)

    Fedotov, E. S.; Khramtsov, I. V.; Kustov, O. Yu.

    2016-10-01

    Numerical simulation of the acoustic processes in an impedance tube at high levels of acoustic pressure is a way to solve a problem of noise suppressing by liners. These studies used liner specimen that is one cylindrical Helmholtz resonator. The evaluation of the real and imaginary parts of the liner acoustic impedance and sound absorption coefficient was performed for sound pressure levels of 130, 140 and 150 dB. The numerical simulation used experimental data having been obtained on the impedance tube with normal incidence waves. At the first stage of the numerical simulation it was used the linearized Navier-Stokes equations, which describe well the imaginary part of the liner impedance whatever the sound pressure level. These equations were solved by finite element method in COMSOL Multiphysics program in axisymmetric formulation. At the second stage, the complete Navier-Stokes equations were solved by direct numerical simulation in ANSYS CFX in axisymmetric formulation. As the result, the acceptable agreement between numerical simulation and experiment was obtained.

  12. Monitoring Thermal Fatigue Damage In Nuclear Power Plant Materials Using Acoustic Emission

    SciTech Connect

    Meyer, Ryan M.; Ramuhalli, Pradeep; Watson, Bruce E.; Pitman, Stan G.; Roosendaal, Timothy J.; Bond, Leonard J.

    2012-04-26

    Proactive aging management of nuclear power plant passive components requires technologies to enable monitoring and accurate quantification of material condition at early stages of degradation (i.e., pre-macrocrack). Acoustic emission (AE) is well-suited to continuous monitoring of component degradation and is proposed as a method to monitor degradation during accelerated thermal fatigue tests. A key consideration is the ability to separate degradation responses from external sources such as water spray induced during thermal fatigue testing. Water spray provides a significant background of acoustic signals, which can overwhelm AE signals caused by degradation. Analysis of AE signal frequency and energy is proposed in this work as a means for separating degradation signals from background sources. Encouraging results were obtained by applying both frequency and energy filters to preliminary data. The analysis of signals filtered using frequency and energy provides signatures exhibiting several characteristics that are consistent with degradation accumulation in materials. Future work is planned to enable verification of the efficacy of AE for thermal fatigue crack initiation detection. While the emphasis has been placed on the use of AE for crack initiation detection during accelerated aging tests, this work also has implications with respect to the use of AE as a primary tool for early degradation monitoring in nuclear power plant materials. The development of NDE tools for characterization of aging in materials can also benefit from the use of a technology such as AE which can continuously monitor and detect crack initiation during accelerated aging tests.

  13. Shear-horizontal surface acoustic wave phononic device with high density filling material for ultra-low power sensing applications

    SciTech Connect

    Richardson, M.; Bhethanabotla, V. R.; Sankaranarayanan, S. K. R. S.

    2014-06-23

    Finite element simulations of a phononic shear-horizontal surface acoustic wave (SAW) sensor based on ST 90°-X Quartz reveal a dramatic reduction in power consumption. The phononic sensor is realized by artificially structuring the delay path to form an acoustic meta-material comprised of a periodic microcavity array incorporating high-density materials such as tantalum or tungsten. Constructive interference of the scattered and secondary reflected waves at every microcavity interface leads to acoustic energy confinement in the high-density regions translating into reduced power loss. Tantalum filled cavities show the best performance while tungsten inclusions create a phononic bandgap. Based on our simulation results, SAW devices with tantalum filled microcavities were fabricated and shown to significantly decrease insertion loss. Our findings offer encouraging prospects for designing low power, highly sensitive portable biosensors.

  14. Measurement of Acoustic Intensity Distribution and Radiation Power of Flat-Plate Phased-Array Sound Source

    NASA Astrophysics Data System (ADS)

    Yokoyama, Tomoki; Takahashi, Kumiko; Seki, Daizaburou; Hasegawa, Akio

    2002-05-01

    The acoustic intensity distribution and radiation power of a flat-plate phased-array sound source consisting of Tonpilz-type transducers were measured. This study shows that the active acoustic intensity is skewed in the direction of wave propagation. In addition, it clarifies that if the measurement is carried out in the immediate vicinity of the sound source, the reactive acoustic intensity distribution is effective for identifying the positions of the individual sound source elements. Experimental values of active radiation power agree well with theoretical values. Conversely, experimental values of reactive radiation power do not agree with theoretical values; it is clear that they fluctuate significantly with distance from the radiating surface. The reason for this is explained in the case of a point sound source.

  15. High Power Amplifier Harmonic Output Level Measurement

    NASA Technical Reports Server (NTRS)

    Perez, R. M.; Hoppe, D. J.; Khan, A. R.

    1995-01-01

    A method is presented for the measurement of the harmonic output power of high power klystron amplifiers, involving coherent hemispherical radiation pattern measurements of the radiated klystron output. Results are discussed for the operation in saturated and unsaturated conditions, and with a waveguide harmonic filter included.

  16. ACOUSTIC SCALE FROM THE ANGULAR POWER SPECTRA OF SDSS-III DR8 PHOTOMETRIC LUMINOUS GALAXIES

    SciTech Connect

    Seo, Hee-Jong; Ho, Shirley; White, Martin; Reid, Beth; Schlegel, David J.; Cuesta, Antonio J.; Padmanabhan, Nikhil; Ross, Ashley J.; Percival, Will J.; Nichol, Robert C.; Saito, Shun; De Putter, Roland; Eisenstein, Daniel J.; Xu Xiaoying; Skibba, Ramin; Schneider, Donald P.; Verde, Licia; Bizyaev, Dmitry; Brewington, Howard; Brinkmann, J.; and others

    2012-12-10

    We measure the acoustic scale from the angular power spectra of the Sloan Digital Sky Survey III (SDSS-III) Data Release 8 imaging catalog that includes 872, 921 galaxies over {approx}10,000 deg{sup 2} between 0.45 < z < 0.65. The extensive spectroscopic training set of the Baryon Oscillation Spectroscopic Survey luminous galaxies allows precise estimates of the true redshift distributions of galaxies in our imaging catalog. Utilizing the redshift distribution information, we build templates and fit to the power spectra of the data, which are measured in our companion paper, to derive the location of Baryon acoustic oscillations (BAOs) while marginalizing over many free parameters to exclude nearly all of the non-BAO signal. We derive the ratio of the angular diameter distance to the sound horizon scale D{sub A} (z)/r{sub s} = 9.212{sup +0.416}{sub -{sub 0.404}} at z = 0.54, and therefore D{sub A} (z) = 1411 {+-} 65 Mpc at z = 0.54; the result is fairly independent of assumptions on the underlying cosmology. Our measurement of angular diameter distance D{sub A} (z) is 1.4{sigma} higher than what is expected for the concordance {Lambda}CDM, in accordance to the trend of other spectroscopic BAO measurements for z {approx}> 0.35. We report constraints on cosmological parameters from our measurement in combination with the WMAP7 data and the previous spectroscopic BAO measurements of SDSS and WiggleZ. We refer to our companion papers (Ho et al.; de Putter et al.) for investigations on information of the full power spectrum.

  17. Baryon acoustic oscillations in 2D: Modeling redshift-space power spectrum from perturbation theory

    SciTech Connect

    Taruya, Atsushi; Nishimichi, Takahiro; Saito, Shun

    2010-09-15

    We present an improved prescription for the matter power spectrum in redshift space taking proper account of both nonlinear gravitational clustering and redshift distortion, which are of particular importance for accurately modeling baryon acoustic oscillations (BAOs). Contrary to the models of redshift distortion phenomenologically introduced but frequently used in the literature, the new model includes the corrections arising from the nonlinear coupling between the density and velocity fields associated with two competitive effects of redshift distortion, i.e., Kaiser and Finger-of-God effects. Based on the improved treatment of perturbation theory for gravitational clustering, we compare our model predictions with the monopole and quadrupole power spectra of N-body simulations, and an excellent agreement is achieved over the scales of BAOs. Potential impacts on constraining dark energy and modified gravity from the redshift-space power spectrum are also investigated based on the Fisher-matrix formalism, particularly focusing on the measurements of the Hubble parameter, angular diameter distance, and growth rate for structure formation. We find that the existing phenomenological models of redshift distortion produce a systematic error on measurements of the angular diameter distance and Hubble parameter by 1%-2%, and the growth-rate parameter by {approx}5%, which would become non-negligible for future galaxy surveys. Correctly modeling redshift distortion is thus essential, and the new prescription for the redshift-space power spectrum including the nonlinear corrections can be used as an accurate theoretical template for anisotropic BAOs.

  18. Comment on "Increase in voice level and speaker comfort in lecture rooms" [J. Acoust. Soc. Am. 125, 2072-2082 (2009)] (L).

    PubMed

    Pelegrín-García, David

    2011-03-01

    Recently, a paper written by Brunskog Gade, Payá-Ballester and Reig-Calbo, "Increase in voice level and speaker comfort in lecture rooms" [J. Acoust. Soc. Am. 125, 2072-2082 (2009)] related teachers' variation in vocal intensity during lecturing to the room acoustic conditions, introducing an objective parameter called "room gain" to describe these variations. In a failed attempt to replicate the objective measurements by Brunskog et al., a simplified and improved method for the calculation of room gain is proposed, in addition with an alternative magnitude called "voice support." The measured parameters are consistent with those of other studies and are used here to build two empirical models relating the voice power levels measured by Brunskog et al., to the room gain and the voice support.

  19. Microwave power transmission system wherein level of transmitted power is controlled by reflections from receiver

    NASA Technical Reports Server (NTRS)

    Robinson, W. J., Jr. (Inventor)

    1974-01-01

    A microwave, wireless, power transmission system is described in which the transmitted power level is adjusted to correspond with power required at a remote receiving station. Deviations in power load produce an antenna impedance mismatch causing variations in energy reflected by the power receiving antenna employed by the receiving station. The variations in reflected energy are sensed by a receiving antenna at the transmitting station and used to control the output power of a power transmitter.

  20. Small scale aspects of warm dark matter: Power spectra and acoustic oscillations

    SciTech Connect

    Boyanovsky, Daniel; Wu Jun

    2011-02-15

    We provide a semianalytic derivation of approximate evolution equations for density perturbations of warm dark matter candidates that decoupled while relativistic with arbitrary distribution functions, their solutions at small scales, and a simple numerical implementation that yields their transfer functions and power spectra. Density perturbations evolve through three stages: radiation domination when the particle is relativistic and nonrelativistic and matter domination. An early integrated Sachs-Wolfe effect during the first stage leads to an enhancement of density perturbations and a plateau in the transfer function for k < or approx. k{sub fs}, the free-streaming wave vector. An effective fluid description emerges at small scales which includes the effects of free streaming in initial conditions and inhomogeneities. The transfer function features warm dark matter acoustic oscillations at scales k > or approx. 2k{sub fs}. A simple analytic interpolation of the power spectra between large and small scales and a numerical implementation valid for arbitrary distribution functions is provided. As an application we study the power spectra for two models of sterile neutrinos with m{approx}keV produced nonresonantly and compare our results to those obtained from Boltzmann codes.

  1. 7. VIEW NORTHEAST, Interior of Power Station, upper level showing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. VIEW NORTHEAST, Interior of Power Station, upper level showing windows on east and north elevations - Bay City Traction & Electric Company, Power Station, 301 Washington Street, Bay City, Bay County, MI

  2. 9. VIEW SOUTHEAST, Interior of Power Station, upper level showing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. VIEW SOUTHEAST, Interior of Power Station, upper level showing windows on east and south elevations - Bay City Traction & Electric Company, Power Station, 301 Washington Street, Bay City, Bay County, MI

  3. ELECTRICAL SWITCHBOARD IN UPPER LEVEL OF HYDROELECTRIC POWER HOUSE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    ELECTRICAL SWITCHBOARD IN UPPER LEVEL OF HYDROELECTRIC POWER HOUSE - St. Lucie Canal, Lock No. 1, Hydroelectric Power House, St. Lucie, Cross State Canal, Okeechobee Intracoastal Waterway, Stuart, Martin County, FL

  4. The acoustic environment of the Florida manatee: Correlation with level of habitat use

    NASA Astrophysics Data System (ADS)

    Miksis-Olds, Jennifer L.; Miller, James H.; Tyack, Peter L.

    2004-05-01

    The Florida manatee is regularly exposed to high volumes of vessel traffic and other human-related noise pollutants because of their coastal distribution. Quantifying specific aspects of the manatees' acoustic environment will allow for a better understanding of how these animals are responding to both natural and human induced changes in their environment. Acoustic recordings and transmission loss measurements were made in two critical manatee habitats: seagrass beds and dredged basins. Twenty-four sampling sites were chosen based on the frequency of manatee presence in specific areas from 2000-2003. Recordings were composed of both ambient noise levels and transient noise sources. The Monterey-Miami Parabolic Equation Model (MMPE) was used to relate environmental parameters to transmission loss, and model outputs were verified by field tests at all sites. Preliminary results indicate that high-use grassbeds have higher levels of transmission loss compared to low-use sites. Additionally, high-use grassbeds have lower ambient noise in the early morning and later afternoon hours compared to low-use grassbeds. The application of noise measurements and model results can now be used to predict received levels, signal-to-noise ratios, and reliable detection of biologically relevant signals in manatee habitats and in the many different environments that marine mammals live.

  5. The acoustic environment of the Florida manatee: Correlation with level of habitat use

    NASA Astrophysics Data System (ADS)

    Miksis-Olds, Jennifer L.; Miller, James H.; Tyack, Peter L.

    2001-05-01

    The Florida manatee is regularly exposed to high volumes of vessel traffic and other human-related noise pollutants because of their coastal distribution. Quantifying specific aspects of the manatees' acoustic environment will allow for a better understanding of how these animals are responding to both natural and human induced changes in their environment. Acoustic recordings and transmission loss measurements were made in two critical manatee habitats: seagrass beds and dredged basins. Twenty-four sampling sites were chosen based on the frequency of manatee presence in specific areas from 2000-2003. Recordings were composed of both ambient noise levels and transient noise sources. The Monterey-Miami Parabolic Equation Model (MMPE) was used to relate environmental parameters to transmission loss, and model outputs were verified by field tests at all sites. Preliminary results indicate that high-use grassbeds have higher levels of transmission loss compared to low-use sites. Additionally, high-use grassbeds have lower ambient noise in the early morning and later afternoon hours compared to low-use grassbeds. The application of noise measurements and model results can now be used to predict received levels, signal-to-noise ratios, and reliable detection of biologically relevant signals in manatee habitats and in the many different environments that marine mammals live.

  6. Power Analysis in Two-Level Unbalanced Designs

    ERIC Educational Resources Information Center

    Konstantopoulos, Spyros

    2010-01-01

    Previous work on statistical power has discussed mainly single-level designs or 2-level balanced designs with random effects. Although balanced experiments are common, in practice balance cannot always be achieved. Work on class size is one example of unbalanced designs. This study provides methods for power analysis in 2-level unbalanced designs…

  7. Multi-level Full Virtualization of Power Management

    NASA Astrophysics Data System (ADS)

    Liu, Yongpeng; Chi, Wanqing; Liu, Yongyan

    Virtual machine technique is employed to improve system utilization and energy efficiency. However, isolation effect of virtualization imposes challenges to power management. A multi-level power behavior statistic framework is introduced to support power profiling of virtual device, virtual machine and host. Power management mechanisms are virtualized to map power management operations between virtual device and physical device. The power consumption of a virtual device is virtualized according to its performance share from the physical device. The experiments demonstrated that our power management virtualization solution has negligible decline of system performance.

  8. Cortisol levels in hair reflect behavioural reactivity of dogs to acoustic stimuli.

    PubMed

    Siniscalchi, M; McFarlane, J R; Kauter, K G; Quaranta, A; Rogers, L J

    2013-02-01

    Cortisol levels in hair samples were examined in fourteen domestic dogs and related to the dogs' responses to different acoustic stimuli. Stimuli were playbacks of species-typical vocalizations recorded during three different situations ("disturbance", "isolation" and "play" barks) and the sounds of a thunderstorm. Hair samples were collected at 9:00 h and 17:00 h two weeks after the behavioural tests. Results showed that behavioural reactivity to playback of the various stimuli correlates with cortisol levels in hair samples collected at 9:00 h, and the same was the case for the separate measures of behaviour (i.e. hiding, running away, seeking attention from the tester, panting and lowering of the body posture). Hence, levels of cortisol in hair appear to reflect the dog's chronic state of emotional reactivity, or temperament.

  9. Studies of acoustic-electric feed-throughs for power transmission through structures

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Doty, Benjamin; Badescu, Mircea; Bao, Xiaoqi; Bar-Cohen, Yoseph; Aldrich, Jack; Chang, Zensheu

    2006-01-01

    There are numerous engineering design problems where the use of wires to transfer power and communicate data thru the walls of a structure is prohibitive or significantly difficult that it may require a complex design. Using physical feedthroughs in such systems may make them susceptible to leakage of chemicals or gasses, loss of pressure or vacuum, as well as difficulties in providing adequate thermal or electrical insulation. Moreover, feeding wires thru a wall of a structure reduces the strength of the structure and makes the structure prone to cracking due to fatigue that can result from cyclic loading and stress concentrations. One area that has already been identified to require a wireless alternative to electrical feedthroughs is the container of the Mars Sample Return Mission, which will need wireless sensors to sense a pressure leak and to avoid potential contamination. The idea of using elastic or acoustic waves to transfer power was suggested recently by [Y. Hu, et al., July 2003]. This system allows for the avoidance of cabling or wiring. The technology is applicable to the transfer of power for actuation, sensing and other tasks inside any sealed container or vacuum/pressure vessel. An alternative approach to the modeling presented previously [Sherrit et a., 2005] used network analysis to solve the same problem in a clear and expandable manner. Experimental tests on three different designs of these devices were performed. The three designs used different methods of coupling the piezoelectric element to the wall. In the first test the piezoelectric material was bolted using a backing structure. In the second test the piezoelectric was clamped after the application of grease and finally the piezoelectric element was attached using a conductive epoxy. The mechanical clamp with grease produced the highest measured efficiency of 53% however this design was the least practical from a fabrication viewpoint. The power transfer efficiency of conductive epoxy

  10. Relations among subglottal pressure, breathing, and acoustic parameters of sentence-level prominence in German.

    PubMed

    Petrone, Caterina; Fuchs, Susanne; Koenig, Laura L

    2017-03-01

    This study investigates whether acoustic correlates of prominence are related to actions of the respiratory system resulting in local changes of subglottal pressure (Psub). Simultaneous recordings were made of acoustics; intraoral pressure (Pio), as an estimate of Psub; and thoracic and abdominal volume changes. Ten German speakers read sentences containing a verb ending with /t/ followed by a noun starting with /t/. These /t#t/ sequences were typically realized as one /t:/ with a long intraoral pressure plateau. Sentence-level prominence was manipulated by shifting the position of contrastive focus within the sentences. The slope and peak values of Pio within the /t#t/ sequence were used to estimate differences in Psub across focus positions. Results show that prominence production is related to changes in the slope and maximum value of the pressure plateau. While pressure increases led to higher intensity, the increases did not relate to f0, hence, suggesting that local f0 changes primarily reflect laryngeal activity. Finally, strong individual differences were observed in the respiratory data. These findings confirm past reports of local Psub increases corresponding to sentence-level prominence. Speaker-specific activations of the respiratory system are interpreted in terms of motor equivalence, with laryngeal mechanisms also appearing to contribute to Psub changes.

  11. Digital stroboscopic holographic interferometry for power flow measurements in acoustically driven membranes

    NASA Astrophysics Data System (ADS)

    Keustermans, William; Pires, Felipe; De Greef, Daniël; Vanlanduit, Steve J. A.; Dirckx, Joris J. J.

    2016-06-01

    Despite the importance of the eardrum and the ossicles in the hearing chain, it remains an open question how acoustical energy is transmitted between them. Identifying the transmission path at different frequencies could lead to valuable information for the domain of middle ear surgery. In this work a setup for stroboscopic holography is combined with an algorithm for power flow calculations. With our method we were able to accurately locate the power sources and sinks in a membrane. The setup enabled us to make amplitude maps of the out-of-plane displacement of a vibrating rubber membrane at subsequent instances of time within the vibration period. From these, the amplitude maps of the moments of force and velocities are calculated. The magnitude and phase maps are extracted from this amplitude data, and form the input for the power flow calculations. We present the algorithm used for the measurements and for the power flow calculations. Finite element models of a circular plate with a local energy source and sink allowed us to test and optimize this algorithm in a controlled way and without the present of noise, but will not be discussed below. At the setup an earphone was connected with a thin tube which was placed very close to the membrane so that sound impinges locally on the membrane, hereby acting as a local energy source. The energy sink was a little piece of foam carefully placed against the membrane. The laser pulses are fired at selected instants within the vibration period using a 30 mW HeNe continuous wave laser (red light, 632.8 nm) in combination with an acousto-optic modulator. A function generator controls the phase of these illumination pulses and the holograms are recorded using a CCD camera. We present the magnitude and phase maps as well as the power flow measurements on the rubber membrane. Calculation of the divergence of this power flow map provides a simple and fast way of identifying and locating an energy source or sink. In conclusion

  12. Acoustic agglomeration of power plant fly ash: Quarterly technical report, 5 November 1986--5 February 1987

    SciTech Connect

    Reethof, G.

    1987-03-20

    High-intensity, high-efficiency sound sources are needed for acoustic agglomeration of particle-laden aerosols in power plant flues and for combustion enhancement. The theory of the linear model is reviewed and show to be in strong disagreement with experimental results. A theoretical study of the sound generation mechanism in sirens is then presented. The various sound attenuation mechanisms are reviewed and a low frequency numerical solution for the frequency response is given which includes arbitrary attenuation, dispersion, horn shape, and mean flow. Next finite-amplitude sound propagation in a horn is studied. Results are presented that agree very well with experimental data. Important nonlinear phenomena such as shock formation, acoustic saturation, and distortion of initially non-sinusoidal finite- amplitude waves are discussed. Finally, a new siren design methodology is presented, including a step-by-step discussion on hot to minimize the acoustic losses. 8 figs.

  13. An ultra-low power and flexible acoustic modem design to develop energy-efficient underwater sensor networks.

    PubMed

    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.

  14. 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

  15. Acoustic agglomeration of power-plant fly ash. A comprehensive semi-annual progress report

    SciTech Connect

    Reethof, G.

    1980-02-01

    Results obtained during the reporting period are presented. The agglomeration of submicron fly ash particles has been studied as a function of sound pressure level, sound frequency, loading, and exposure time. A second generation model of the agglomeration process is being developed. A high-frequency, high-intensity variable speed siren delivering at least 600 W at frequencies up to 4000 Hz has been developed and tested. Details on the design and operation are presented. The agglomeration chamber has been completely cleaned and the aerosol generating system has been rebuilt. A mathematical model of the acoustics of agglomeration is being developed. Preliminary results of computerized electron microscopic scanning of fly ash particles during agglomeration are presented. (DMC)

  16. Encoding of nested levels of acoustic regularity in hierarchically organized areas of the human auditory cortex.

    PubMed

    Recasens, Marc; Grimm, Sabine; Wollbrink, Andreas; Pantev, Christo; Escera, Carles

    2014-11-01

    Our auditory system is able to encode acoustic regularity of growing levels of complexity to model and predict incoming events. Recent evidence suggests that early indices of deviance detection in the time range of the middle-latency responses (MLR) precede the mismatch negativity (MMN), a well-established error response associated with deviance detection. While studies suggest that only the MMN, but not early deviance-related MLR, underlie complex regularity levels, it is not clear whether these two mechanisms interplay during scene analysis by encoding nested levels of acoustic regularity, and whether neuronal sources underlying local and global deviations are hierarchically organized. We registered magnetoencephalographic evoked fields to rapidly presented four-tone local sequences containing a frequency change. Temporally integrated local events, in turn, defined global regularities, which were infrequently violated by a tone repetition. A global magnetic mismatch negativity (MMNm) was obtained at 140-220 ms when breaking the global regularity, but no deviance-related effects were shown in early latencies. Conversely, Nbm (45-55 ms) and Pbm (60-75 ms) deflections of the MLR, and an earlier MMNm response at 120-160 ms, responded to local violations. Distinct neuronal generators in the auditory cortex underlay the processing of local and global regularity violations, suggesting that nested levels of complexity of auditory object representations are represented in separated cortical areas. Our results suggest that the different processing stages and anatomical areas involved in the encoding of auditory representations, and the subsequent detection of its violations, are hierarchically organized in the human auditory cortex.

  17. Influences of environmental noise level and respiration rate on the accuracy of acoustic respiration rate monitoring.

    PubMed

    Yabuki, Shizuha; Toyama, Hiroaki; Takei, Yusuke; Wagatsuma, Toshihiro; Yabuki, Hiroshi; Yamauchi, Masanori

    2017-02-07

    We tested the hypothesis that the environmental noise generated by a forced-air warming system reduces the monitoring accuracy of acoustic respiration rate (RRa). Noise levels were adjusted to 45-55, 56-65, 66-75, and 76-85 dB. Healthy participants breathed at set respiration rates (RRset) of 6, 12, and 30/min. Under each noise level at each RRset, the respiration rates by manual counting (RRm) and RRa were recorded. Any appearance of the alarm display on the RRa monitor was also recorded. Each RRm of all participants agreed with each RRset at each noise level. At 45-55 dB noise, the RRa of 13, 17, and 17 participants agreed with RRset of 6, 12, and 30/min, respectively. The RRa of 14, 17, and 16 participants at 56-65 dB noise, agreed with RRset of 6, 12, and 30/min, respectively. At 66-75 dB noise, the RRa of 9, 15, and 16 participants agreed with RRset of 6, 12, and 30/min, respectively. The RRa of one, nine, and nine participants at 76-85 dB noise agreed with RRset of 6, 12, and 30/min, respectively, which was significantly less than the other noise levels (P < 0.05). Overall, 72.9% of alarm displays highlighted incorrect values of RRa. In a noisy situation involving the operation of a forced-air warming system, the acoustic respiration monitoring should be used carefully especially in patients with a low respiration rate.

  18. Baseline acoustic levels of the NASA Active Noise Control Fan rig

    NASA Technical Reports Server (NTRS)

    Sutliff, Daniel L.; Heidelberg, Laurence J.; Elliott, David M.; Nallasamy, M.

    1996-01-01

    Extensive measurements of the spinning acoustic mode structure in the NASA 48 inch Active Noise Control Fan (ANCF) test rig have been taken. A continuously rotating microphone rake system with a least-squares data reduction technique was employed to measure these modes in the inlet and exhaust. Farfield directivity patterns in an anechoic environment were also measured at matched corrected rotor speeds. Several vane counts and spacings were tested over a range of rotor speeds. The Eversman finite element radiation code was run with the measured in-duct modes as input and the computed farfield results were compared to the experimentally measured directivity pattern. The experimental data show that inlet spinning mode measurements can be made very accurately. Exhaust mode measurements may have wake interference, but the least-squares reduction does a good job of rejecting the non-acoustic pressure. The Eversman radiation code accurately extrapolates the farfield levels and directivity pattern when all in-duct modes are included.

  19. Locational Marginal Pricing in the Campus Power System at the Power Distribution Level

    SciTech Connect

    Hao, Jun; Gu, Yi; Zhang, Yingchen; Zhang, Jun Jason; Gao, David Wenzhong

    2016-11-14

    In the development of smart grid at distribution level, the realization of real-time nodal pricing is one of the key challenges. The research work in this paper implements and studies the methodology of locational marginal pricing at distribution level based on a real-world distribution power system. The pricing mechanism utilizes optimal power flow to calculate the corresponding distributional nodal prices. Both Direct Current Optimal Power Flow and Alternate Current Optimal Power Flow are utilized to calculate and analyze the nodal prices. The University of Denver campus power grid is used as the power distribution system test bed to demonstrate the pricing methodology.

  20. Predicted and Measured Modal Sound Power Levels for a Fan Ingesting Distorted Inflow

    NASA Technical Reports Server (NTRS)

    Koch, L. Danielle

    2010-01-01

    Refinements have been made to a method for estimating the modal sound power levels of a ducted fan ingesting distorted inflow. By assuming that each propagating circumferential mode consists only of a single radial mode (the one with the highest cut-off ratio), circumferential mode sound power levels can be computed for a variety of inflow distortion patterns and operating speeds. Predictions from the refined theory have been compared to data from an experiment conducted in the Advanced Noise Control Fan at NASA Glenn Research Center. The inflow to the fan was distorted by inserting cylindrical rods radially into the inlet duct. The rods were placed at an axial location one rotor chord length upstream of the fan and arranged in both regular and irregular circumferential patterns. The fan was operated at 2000, 1800, and 1400 rpm. Acoustic pressure levels were measured in the fan inlet and exhaust ducts using the Rotating Rake fan mode measurement system. Far field sound pressure levels were also measured. It is shown that predicted trends in circumferential mode sound power levels closely match the experimental data for all operating speeds and distortion configurations tested. Insight gained through this work is being used to develop more advanced tools for predicting fan inflow distortion tone noise levels.

  1. Offshore exposure experiments on cuttlefish indicate received sound pressure and particle motion levels associated with acoustic trauma

    PubMed Central

    Solé, Marta; Sigray, Peter; Lenoir, Marc; van der Schaar, Mike; Lalander, Emilia; André, Michel

    2017-01-01

    Recent findings on cephalopods in laboratory conditions showed that exposure to artificial noise had a direct consequence on the statocyst, sensory organs, which are responsible for their equilibrium and movements in the water column. The question remained about the contribution of the consequent near-field particle motion influence from the tank walls, to the triggering of the trauma. Offshore noise controlled exposure experiments (CEE) on common cuttlefish (Sepia officinalis), were conducted at three different depths and distances from the source and particle motion and sound pressure measurements were performed at each location. Scanning electron microscopy (SEM) revealed injuries in statocysts, which severity was quantified and found to be proportional to the distance to the transducer. These findings are the first evidence of cephalopods sensitivity to anthropogenic noise sources in their natural habitat. From the measured received power spectrum of the sweep, it was possible to determine that the animals were exposed at levels ranging from 139 to 142 dB re 1 μPa2 and from 139 to 141 dB re 1 μPa2, at 1/3 octave bands centred at 315 Hz and 400 Hz, respectively. These results could therefore be considered a coherent threshold estimation of noise levels that can trigger acoustic trauma in cephalopods. PMID:28378762

  2. Offshore exposure experiments on cuttlefish indicate received sound pressure and particle motion levels associated with acoustic trauma.

    PubMed

    Solé, Marta; Sigray, Peter; Lenoir, Marc; van der Schaar, Mike; Lalander, Emilia; André, Michel

    2017-04-05

    Recent findings on cephalopods in laboratory conditions showed that exposure to artificial noise had a direct consequence on the statocyst, sensory organs, which are responsible for their equilibrium and movements in the water column. The question remained about the contribution of the consequent near-field particle motion influence from the tank walls, to the triggering of the trauma. Offshore noise controlled exposure experiments (CEE) on common cuttlefish (Sepia officinalis), were conducted at three different depths and distances from the source and particle motion and sound pressure measurements were performed at each location. Scanning electron microscopy (SEM) revealed injuries in statocysts, which severity was quantified and found to be proportional to the distance to the transducer. These findings are the first evidence of cephalopods sensitivity to anthropogenic noise sources in their natural habitat. From the measured received power spectrum of the sweep, it was possible to determine that the animals were exposed at levels ranging from 139 to 142 dB re 1 μPa(2) and from 139 to 141 dB re 1 μPa(2), at 1/3 octave bands centred at 315 Hz and 400 Hz, respectively. These results could therefore be considered a coherent threshold estimation of noise levels that can trigger acoustic trauma in cephalopods.

  3. Deep water pipeline intervention work with an acoustically controlled power module

    SciTech Connect

    Conter, A.; Launaro, F.; Bigoni, G.

    1995-12-31

    The stabilisation of submarine pipeline free spans along uneven sea bottoms is conventionally performed using technologies such as gravel dumping, post trenching, matresses installation etc.. A new technology has been developed to support free spans along the 26 inches Transmed Gas Pipelines crossing the Sicily Channel in water depths ranging from 50m to 510m. This technology is based on the pipeline mechanical supports {open_quotes}Atlantis{close_quotes} and their installation module {open_quotes}Pegaso{close_quotes} and was developed having in mind requirements such as short installation time, system redundancy, operational flexibility and simple interface with the support vessel. The installation time reduction is achieved by automatic operational procedures which are acoustically controlled from surface. Power is stored inside two dedicated battery packs placed onboard Pegaso; no umbilical cable is necessary so that a vessel equipped with a normal crane is enough to launch and operate the system. Marine operations carried out in 1993 showed that a support can be installed in about one hour; in good weather conditions three Atlantis were installed in 24 hours including deck operations for recharging the battery packs; as a total sixteen supports were installed along the 4th and 5th Transmed Gas Pipelines. The system has proved to be a cost effective and flexible alternative to conventional technologies for free span support, especially in deep waters. A cost/benefit analysis also shows the breakeven point of the new technology versus gravel dumping.

  4. Experimental facility for the study of acoustic emission registered in the primary circuit components of WWER power units

    NASA Astrophysics Data System (ADS)

    Petrosyan, V. G.; Hovakimyan, T. H.; Yeghoyan, E. A.; Hovhannisyan, H. T.; Mayilyan, D. G.; Petrosyan, A. P.

    2017-01-01

    This paper is dedicated to the creation of a facility for the experimental study of a phenomenon of background acoustic emission (AE), which is detected in the main circulation loop (MCL) of WWER power units. The analysis of the operating principle and the design of a primary feed-and-blow down system (FB) deaerator of NPP as the most likely source of continuous acoustic emission is carried out. The experimental facility for the systematic study of a phenomenon of continuous AE is developed. A physical model of a thermal deaerator is designed and constructed. A thermal monitoring system is introduced. An automatic system providing acoustic signal registration in a low frequency (0.03-30 kHz) and high frequency (30-300 kHz) bands and study of its spectral characteristics is designed. Special software for recording and processing of digitized electrical sensor signals is developed. A separate and independent principle of study of the most probable processes responsible for the generation of acoustic emission signals in the deaerator is applied. Trial series of experiments and prechecks of acoustic signals in different modes of the deaerator model are conducted. Compliance of basic technological parameters with operating range of the real deaerator was provided. It is shown that the acoustic signal time-intensity curve has several typical regions. The pilot research showed an impact of various processes that come about during the operation of the deaerator physical model on the intensity of the AE signal. The experimental results suggest that the main sources of generation of the AE signals are the processes of steam condensation, turbulent flow of gas-vapor medium, and water boiling.

  5. MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED THERMAL-ACOUSTIC EFFECT TO MEASURE UNBURNED CARBON

    SciTech Connect

    Robert C. Brown; Robert J. Weber; Jeffrey J. Swetelitsch

    2005-01-01

    The objective of this project is to explore microwave-excited thermal-acoustic (META) phenomena for quantitative analysis of granular and powdered materials, with the culmination of the research to be an on-line carbon-in-ash monitor for coal-fired power plants. This technique of analyzing unburned carbon in fly ash could be a less tedious and time consuming method as compared to the traditional LOI manual procedure. Phase 1 of the research focused on off-line single-frequency thermal-acoustic measurements where an off-line fly ash monitor was constructed that could operate as analytical tool to explore instrument and methodology parameters for quantifying the microwave-excited thermal-acoustic effect of carbon in fly ash, and it was determined that the off-line thermal-acoustic technique could predict the carbon content of a random collection of fly ashes with a linear correlation constant of R{sup 2} = 0.778. Much higher correlations are expected for fly ashes generated from a single boiler. Phase 2 of the research developing a methodology to generate microwave spectra of various powders, including fly ash, coal, and inorganic minerals, and to determine if these microwave spectra could be used for chemical analyses. Although different minerals produced different responses, higher resolution microwave spectra would be required to be able to distinguish among minerals. Phase 3 of the research focused on the development of an on-line fly ash monitor that could be adapted to measure either a thermal-acoustic or thermal-elastic response to due microwave excitation of fly ash. The thermal-acoustic response was successfully employed for this purpose but the thermal-elastic response was too weak to yield a useful on-line device.

  6. 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.

  7. Differential Use and Benefits of PowerPoint in Upper Level versus Lower Level Courses

    ERIC Educational Resources Information Center

    Roehling, Patricia V.; Trent-Brown, Sonja

    2011-01-01

    The study examines whether college instructors use PowerPoint differently in upper level versus lower level courses and whether PowerPoint differentially affects the learning and behaviours of students in those courses. The authors surveyed 191 students from 14 psychology classes and found that instructors teaching higher level courses use…

  8. Fast, Low-Power, Hysteretic Level-Detector Circuit

    NASA Technical Reports Server (NTRS)

    Arditti, Mordechai

    1993-01-01

    Circuit for detection of preset levels of voltage or current intended to replace standard fast voltage comparator. Hysteretic analog/digital level detector operates at unusually low power with little sacrifice of speed. Comprises low-power analog circuit and complementary metal oxide/semiconductor (CMOS) digital circuit connected in overall closed feedback loop to decrease rise and fall times, provide hysteresis, and trip-level control. Contains multiple subloops combining linear and digital feedback. Levels of sensed signals and hysteresis level easily adjusted by selection of components to suit specific application.

  9. New acoustooptic effect: Constant high diffraction efficiency in wide range of acoustic power

    NASA Astrophysics Data System (ADS)

    Antonov, S. N.; Vainer, A. V.; Proklov, V. V.; Rezvov, Yu. G.

    2009-06-01

    A new effect, viz., acoustooptic Bragg diffraction without the overmodulation mode, in which the efficiency of the Bragg order attains its maximal value (close to 100%) upon an increase in the intensity of an acoustic wave and then remains practically unchanged, is predicted theoretically and observed experimentally. The effect takes place in the case of considerable bending of phase fronts of the acoustic field in the acoustooptic diffraction plane and attains its maximal value at a relatively low frequency of sound, a small width of a piezoelectric transducer, strong acoustic anisotropy of the medium, and a large distance between the light beam and the piezoelectric transducer.

  10. Wireless acoustic-electric feed-through for power and signal transmission

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart (Inventor); Bar-Cohen, Yoseph (Inventor); Bao, Xiaoqi (Inventor); Doty, Benjamin (Inventor); Badescu, Mircea (Inventor); Chang, Zensheu (Inventor)

    2011-01-01

    An embodiment provides electrical energy from a source on one side of a medium to a load on the other side of the medium, the embodiment including a first piezoelectric to generate acoustic energy in response to electrical energy from the source, and a second piezoelectric to convert the received acoustic energy to electrical energy used by the load. Other embodiments are described and claimed.

  11. Influence of acoustics in separation processes

    NASA Technical Reports Server (NTRS)

    Fairbanks, H. V.

    1976-01-01

    The effects of introducing high energy acoustics into various filtering and drying systems were studied. With very slow velocity filtration systems, it was found that the introduction of acoustics could substantially increase the flow rate and also aided in the coagulation of the particulates before reaching the filter media. In the drying of temperature sensitive powders, the rate was increased by the introduction of acoustics. The acoustic frequency used was 20 kHz with power levels up to 3 watts per square centimeter.

  12. [Thermoelastic excitation of acoustic waves in biological models under the effect of the high peak-power pulsed electromagnetic radiation of extremely high frequency].

    PubMed

    Gapeev, A B; Rubanik, A V; Pashovkin, T N; Chemeris, N K

    2007-01-01

    The capability of high peak-power pulsed electromagnetic radiation of extremely high frequency (35,27 GHz, pulse widths of 100 and 600 ns, peak power of 20 kW) to excite acoustic waves in model water-containing objects and muscular tissue of animals has been experimentally shown for the first time. The amplitude and duration of excited acoustic pulses are within the limits of accuracy of theoretical assessments and have a complex nonlinear dependence on the energy input of electromagnetic radiation supplied. The velocity of propagation of acoustic pulses in water-containing models and isolated muscular tissue of animals was close to the reference data. The excitation of acoustic waves in biological systems under the action of high peak-power pulsed electromagnetic radiation of extremely high frequency is the important phenomenon, which essentially contributes to the understanding of the mechanisms of biological effects of these electromagnetic fields.

  13. Power Consideration for Three-Level Growth Models

    ERIC Educational Resources Information Center

    Li, Wei; Konstantopoulos, Spyros

    2016-01-01

    The purpose of this study is extend previous methods by Raudenbush and Liu (2001) and Spybrook et al. (2011), and provide methods for power analysis of tests of treatment effects in studies of polynomial change with two levels of nesting (e.g., students and schools) where the treatment is either at the third level (e.g., school intervention) or at…

  14. User's manual for levelized power generation cost using a microcomputer

    SciTech Connect

    Fuller, L.C.

    1984-08-01

    Microcomputer programs for the estimation of levelized electrical power generation costs are described. Procedures for light-water reactor plants and coal-fired plants include capital investment cost, operation and maintenance cost, fuel cycle cost, nuclear decommissioning cost, and levelized total generation cost. Programs are written in Pascal and are run on an Apple II Plus microcomputer.

  15. Correlation of FEM/BEM Vibroacoustic Prediction to System-Level Acoustic Test Results

    NASA Astrophysics Data System (ADS)

    Rodrigues, G.; Ngan, I.; Santiago-Prowald, J.

    2014-06-01

    Coupled FEM/BEM vibroacoustic analyses are employed for deriving spacecraft random vibration environments and supporting the design of low aerial density structures. They offer deterministic predictions which are very accurate at low-frequency and meaningful across all the spectrum of interest for vibroacoustic response.An assessment of the standard procedure of FEM/BEM vibroacoustic analyses was carried out by correlation to measurements from system-level tests of several spacecraft. This allowed a quantification of the typical errors committed, and concluded on the adequacy of applying the standard factor of safety +4dB to the predictions. It was observed that a major source of error is the lack of representativeness of the models of the spacecraft, which adds to the diffuse field idealization made on the acoustic environment inside the fairing and the test chambers. In particular, it was observed a clear impact from a lack of detail of the damping of the structure, and an often crude lumped representation of units and equipment as well as tanks and fixations.

  16. An acoustic analog for a quantum mechanical level-splitting route to band formation

    NASA Astrophysics Data System (ADS)

    D'Onofrio, Marissa; Crum, Mitchell; Hilbert, Shawn A.; Batelaan, Herman; Canalichio, Timothy; Bull, Tyler

    2016-11-01

    This paper explores band structure in a simple acoustic apparatus that acts as an analog to the quantum infinite square well with multiple delta-function perturbations. The apparatus can be used to visualize abstract quantum phenomena in a concrete and easily understandable way. It consists of regular sections of PVC pipes connected by variable aluminum diaphragms to allow coupling between the pipe sections. The equivalence between standing waves in the acoustic system and stationary states in the quantum system is examined for multiple-cavity situations. We show that the experimental results from the acoustic system and the analytic solutions of the quantum system demonstrate the same resonance structure. We also experimentally show that the acoustic system supports band structure and that the band width is dependent on the hole size of the diaphragms.

  17. Perception of power modulation of light in conjunction with acoustic stimulation

    NASA Astrophysics Data System (ADS)

    Hahlweg, Cornelius F.; Weyer, Cornelia; Gercke-Hahn, Harald; Gutzmann, Holger L.; Brahmann, Andre; Rothe, Hendrik

    2013-09-01

    The present paper is derived from an ongoing study on the human perception of combined optical and acoustical periodical stimuli. Originating from problems of occupational medicine concerning artificial illumination and certain machinery with coherent optical and acoustical emissions there are effects which are interesting in the context of Optics and Music. Because of the difficulties in evaluation of physical and psychological effects of such coherent stimuli in a first step we questioned if such coherence is perceivable at all. Concept, experimental set-up and first results are discussed in short.

  18. A high-powered siren for stable acoustic levitation of dense materials in the earth's gravity

    NASA Astrophysics Data System (ADS)

    Gammel, Paul M.; Croonquist, Arvid P.; Wang, Taylor G.

    1988-02-01

    Levitation of large dense samples (e.g., 1-cm diameter steel balls) has been performed in a 1-g environment. A siren was used to study the effects of reflector geometry and variable-frequency operation in order to attain stable acoustic positioning. The harmonic content and spatial distribution of the acoustic field have been investigated. The best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper reflector while operating at a frequency slightly below resonance.

  19. A high-powered siren for stable acoustic levitation of dense materials in the earth's gravity

    NASA Technical Reports Server (NTRS)

    Gammel, Paul M.; Croonquist, Arvid P.; Wang, Taylor G.

    1988-01-01

    Levitation of large dense samples (e.g., 1-cm diameter steel balls) has been performed in a 1-g environment. A siren was used to study the effects of reflector geometry and variable-frequency operation in order to attain stable acoustic positioning. The harmonic content and spatial distribution of the acoustic field have been investigated. The best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper reflector while operating at a frequency slightly below resonance.

  20. A supervisor for the successive 3D computations of magnetic, mechanical and acoustic quantities in power oil inductors and transformers

    SciTech Connect

    Reyne, G.; Magnin, H.; Berliat, G.; Clerc, C.

    1994-09-01

    A supervisor has been developed so as to allow successive 3D computations of different quantities by different softwares on the same physical problem. Noise of a given power oil transformer can be deduced from the surface vibrations of the tank. These vibrations are obtained through a mechanic computation whose Inputs are the electromagnetic forces provided . by an electromagnetic computation. Magnetic, mechanic and acoustic experimental data are compared with the results of the 3D computations. Stress Is put on the main characteristics of the supervisor such as the transfer of a given quantity from one mesh to the other.

  1. Underwater Wireless Sensor Networks: How Do Acoustic Propagation Models Impact the Performance of Higher-Level Protocols?

    PubMed Central

    Llor, Jesús; Malumbres, Manuel P.

    2012-01-01

    Several Medium Access Control (MAC) and routing protocols have been developed in the last years for Underwater Wireless Sensor Networks (UWSNs). One of the main difficulties to compare and validate the performance of different proposals is the lack of a common standard to model the acoustic propagation in the underwater environment. In this paper we analyze the evolution of underwater acoustic prediction models from a simple approach to more detailed and accurate models. Then, different high layer network protocols are tested with different acoustic propagation models in order to determine the influence of environmental parameters on the obtained results. After several experiments, we can conclude that higher-level protocols are sensitive to both: (a) physical layer parameters related to the network scenario and (b) the acoustic propagation model. Conditions like ocean surface activity, scenario location, bathymetry or floor sediment composition, may change the signal propagation behavior. So, when designing network architectures for UWSNs, the role of the physical layer should be seriously taken into account in order to assert that the obtained simulation results will be close to the ones obtained in real network scenarios. PMID:22438712

  2. Thawing of foods in a microwave oven: I. Effect of power levels and power cycling.

    PubMed

    Chamchong, M; Datta, A K

    1999-01-01

    Microwave thawing is faster than other methods, but it can produce significant non-uniformity of heating. The objective of this study was to perform comprehensive experimentation and heat transfer modeling to relate the time to thaw and the non-uniformity of thawing to power cycling, power level and the surface heat transfer coefficient. The governing energy equation was formulated with an exponential decay of the microwave flux from the surface. Surface microwave flux was obtained from the measured temperature rise using inverse heat transfer analysis. Gradual phase change was formulated as an apparent specific heat, and was obtained for the experimental material tylose from differential scanning calorimetry (DSC) measurements. The temperatures were measured immediately following heating with a fast response thermocouple. Dielectric properties were measured above freezing. Results show that the microwave flux at the surface and its decay are affected by the changes in the power level. Power cycling has an almost identical effect as continuous power at the reduced level of the average cycled power. As power level increases, the surface flux increases by the same fraction. At higher power levels, however, the outside thaws relatively faster. A "shield" develops due to a much reduced microwave penetration depth at the surface. This thawing time at higher power levels is reduced considerably. Temperature increases initially are non-uniform since the surface is heated at a faster rate than the interior. In keeping with the assumption that once the temperature reaches 100 degrees C, all energy absorbed goes into evaporation, and subsequent temperature is maintained at 100 degrees C. Thus, eventually, non-uniformity starts to decrease.

  3. Noise generated by quiet engine fans. 2: Fan A. [measurement of power spectra and sideline perceived noise levels

    NASA Technical Reports Server (NTRS)

    Montegani, F. J.; Schaefer, J. W.; Stakolich, E. G.

    1974-01-01

    A significant effort within the NASA Quiet Engine Program has been devoted to acoustical evaluation at the Lewis Research Center noise test facility of a family of full-scale fans. This report, documents the noise results obtained with fan A - a 1.5-pressure-ratio, 1160-ft/sec-tip-speed fan. The fan is described and some aerodynamic operating data are given. Far-field noise around the fan was measured for a variety of configurations pertaining to acoustical treatment and over a range of operating conditions. Complete results of 1/3-octave band analysis of the data are presented in tabular form. Included also are power spectra and sideline perceived noise levels. Some representative 1/3-octave band data are presented graphically, and sample graphs of continuous narrow-band spectra are also provided.

  4. Watt-level wireless power transmission to multiple compact receivers

    NASA Astrophysics Data System (ADS)

    Garraud, A.; Munzer, D. J.; Althar, M.; Garraud, N.; Arnold, D. P.

    2015-12-01

    This paper reports an electrodynamic wireless power transmission (EWPT) system using a low-frequency (300 Hz) magnetic field to transmit watt-scale power levels to multiple compact receivers. As compared to inductively or resonantly coupled coils, EWPT facilitates transmission to multiple non-interacting receivers with little restriction on their orientation. A single 3.0 cm3 receiver achieves 1.25 W power transmission with 8% efficiency at a distance of 1 cm (350 mW/cm3 power density) from the transmitter. The same prototype achieves 9 mW at a distance of 9 cm. Moreover, we demonstrate simultaneous recharge of two wearable devices, using two receivers located in arbitrary positions and orientations.

  5. Design and implementation of an omni-directional underwater acoustic micro-modem based on a low-power micro-controller unit.

    PubMed

    Won, Tae-Hee; Park, Sung-Joon

    2012-01-01

    For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks (UWSNs) has increased, the research and development of compact and low-power consuming communication devices has become the focus. From the consideration that the requisites of acoustic modems for UWSNs are low power consumption, omni-directional beam pattern, low cost and so on, in this paper, we design and implement an omni-directional underwater acoustic micro-modem satisfying these requirements. In order to execute fast digital domain signal processing and support flexible interfaces with other peripherals, an ARM Cortex-M3 is embedded in the micro-modem. Also, for the realization of small and omni-directional properties, a spherical transducer having a resonant frequency of 70 kHz and a diameter of 34 mm is utilized for the implementation. Physical layer frame format and symbol structure for efficient packet-based underwater communication systems are also investigated. The developed acoustic micro-modem is verified analytically and experimentally in indoor and outdoor environments in terms of functionality and performance. Since the modem satisfies the requirements for use in UWSNs, it could be deployed in a wide range of applications requiring underwater acoustic communication.

  6. Design and Implementation of an Omni-Directional Underwater Acoustic Micro-Modem Based on a Low-Power Micro-Controller Unit

    PubMed Central

    Won, Tae-Hee; Park, Sung-Joon

    2012-01-01

    For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks (UWSNs) has increased, the research and development of compact and low-power consuming communication devices has become the focus. From the consideration that the requisites of acoustic modems for UWSNs are low power consumption, omni-directional beam pattern, low cost and so on, in this paper, we design and implement an omni-directional underwater acoustic micro-modem satisfying these requirements. In order to execute fast digital domain signal processing and support flexible interfaces with other peripherals, an ARM Cortex-M3 is embedded in the micro-modem. Also, for the realization of small and omni-directional properties, a spherical transducer having a resonant frequency of 70 kHz and a diameter of 34 mm is utilized for the implementation. Physical layer frame format and symbol structure for efficient packet-based underwater communication systems are also investigated. The developed acoustic micro-modem is verified analytically and experimentally in indoor and outdoor environments in terms of functionality and performance. Since the modem satisfies the requirements for use in UWSNs, it could be deployed in a wide range of applications requiring underwater acoustic communication. PMID:22438765

  7. Aerobic Capacity and Anaerobic Power Levels of the University Students

    ERIC Educational Resources Information Center

    Taskin, Cengiz

    2016-01-01

    The aim of study was to analyze aerobic capacity and anaerobic power levels of the university students. Total forty university students who is department physical education and department business (age means; 21.15±1.46 years for male and age means; 20.55±1.79 years for female in department physical education), volunteered to participate in this…

  8. A level-set-based topology optimisation for acoustic-elastic coupled problems with a fast BEM-FEM solver

    NASA Astrophysics Data System (ADS)

    Isakari, Hiroshi; Kondo, Toyohiro; Takahashi, Toru; Matsumoto, Toshiro

    2017-03-01

    This paper presents a structural optimisation method in three-dimensional acoustic-elastic coupled problems. The proposed optimisation method finds an optimal allocation of elastic materials which reduces the sound level on some fixed observation points. In the process of the optimisation, configuration of the elastic materials is expressed with a level set function, and the distribution of the level set function is iteratively updated with the help of the topological derivative. The topological derivative is associated with state and adjoint variables which are the solutions of the acoustic-elastic coupled problems. In this paper, the acoustic-elastic coupled problems are solved by a BEM-FEM coupled solver, in which the fast multipole method (FMM) and a multi-frontal solver for sparse matrices are efficiently combined. Along with the detailed formulations for the topological derivative and the BEM-FEM coupled solver, we present some numerical examples of optimal designs of elastic sound scatterer to manipulate sound waves, from which we confirm the effectiveness of the present method.

  9. Design of megawatt power level heat pipe reactors

    SciTech Connect

    Mcclure, Patrick Ray; Poston, David Irvin; Dasari, Venkateswara Rao; Reid, Robert Stowers

    2015-11-12

    An important niche for nuclear energy is the need for power at remote locations removed from a reliable electrical grid. Nuclear energy has potential applications at strategic defense locations, theaters of battle, remote communities, and emergency locations. With proper safeguards, a 1 to 10-MWe (megawatt electric) mobile reactor system could provide robust, self-contained, and long-term power in any environment. Heat pipe-cooled fast-spectrum nuclear reactors have been identified as a candidate for these applications. Heat pipe reactors, using alkali metal heat pipes, are perfectly suited for mobile applications because their nature is inherently simpler, smaller, and more reliable than “traditional” reactors. The goal of this project was to develop a scalable conceptual design for a compact reactor and to identify scaling issues for compact heat pipe cooled reactors in general. Toward this goal two detailed concepts were developed, the first concept with more conventional materials and a power of about 2 MWe and a the second concept with less conventional materials and a power level of about 5 MWe. A series of more qualitative advanced designs were developed (with less detail) that show power levels can be pushed to approximately 30 MWe.

  10. Protoflight photovoltaic power module system-level tests in the Space Power Facility

    NASA Technical Reports Server (NTRS)

    Rivera, Juan C.; Kirch, Luke A.

    1989-01-01

    Work Package Four, which includes the NASA-Lewis and Rocketdyne, has selected an approach for the Space Station Freedom Photovoltaic (PV) Power Module flight certification that combines system level qualification and acceptance testing in the thermal vacuum environment: the 'protoflight' vehicle approach. This approach maximizes ground test verification to assure system level performance and to minimize risk of on-orbit failures. The preliminary plans for system level thermal vacuum environmental testing of the protoflight PV Power Module in the NASA-Lewis Space Power Facility (SPF) are addressed. Details of the facility modifications to refurbish SPF, after 13 years of downtime, are briefly discussed. The results of an evaluation of the effectiveness of system level environmental testing in screening out incipient part and workmanship defects and unique failure modes are discussed. Preliminary test objectives, test hardware configurations, test support equipment, and operations, are presented.

  11. Protoflight photovoltaic power module system-level tests in the space power facility

    NASA Technical Reports Server (NTRS)

    Rivera, Juan C.; Kirch, Luke A.

    1989-01-01

    Work Package Four, which includes the NASA-Lewis and Rocketdyne, has selected an approach for the Space Station Freedom Photovoltaic (PV) Power Module flight certification that combines system level qualification and acceptance testing in the thermal vacuum environment: The protoflight vehicle approach. This approach maximizes ground test verification to assure system level performance and to minimize risk of on-orbit failures. The preliminary plans for system level thermal vacuum environmental testing of the protoflight PV Power Module in the NASA-Lewis Space Power Facility (SPF), are addressed. Details of the facility modifications to refurbish SPF, after 13 years of downtime, are briefly discussed. The results of an evaluation of the effectiveness of system level environmental testing in screening out incipient part and workmanship defects and unique failure modes are discussed. Preliminary test objectives, test hardware configurations, test support equipment, and operations are presented.

  12. Float level switch for a nuclear power plant containment vessel

    DOEpatents

    Powell, James G.

    1993-01-01

    This invention is a float level switch used to sense rise or drop in water level in a containment vessel of a nuclear power plant during a loss of coolant accident. The essential components of the device are a guide tube, a reed switch inside the guide tube, a float containing a magnetic portion that activates a reed switch, and metal-sheathed, ceramic-insulated conductors connecting the reed switch to a monitoring system outside the containment vessel. Special materials and special sealing techniques prevent failure of components and allow the float level switch to be connected to a monitoring system outside the containment vessel.

  13. Float level switch for a nuclear power plant containment vessel

    DOEpatents

    Powell, J.G.

    1993-11-16

    This invention is a float level switch used to sense rise or drop in water level in a containment vessel of a nuclear power plant during a loss of coolant accident. The essential components of the device are a guide tube, a reed switch inside the guide tube, a float containing a magnetic portion that activates a reed switch, and metal-sheathed, ceramic-insulated conductors connecting the reed switch to a monitoring system outside the containment vessel. Special materials and special sealing techniques prevent failure of components and allow the float level switch to be connected to a monitoring system outside the containment vessel. 1 figures.

  14. Generation of Acoustic Gravity Waves by Periodic Radio Transmissions from a High-Power Ionospheric Heater

    NASA Astrophysics Data System (ADS)

    Frolov, Vladimir; Chernogor, Leonid; Rozumenko, Victor

    The Radiophysical Research Institute (Nizhny Novgorod, Russia) and Kharkiv V. N. Karazin National University (Kharkiv, Ukraine) have studied opportunities for the effective generation of acoustic gravity waves (AGWs) in 3 - 180-min period range. The excitation of such waves was conducted for the last several years using the SURA heating facility (Nizhny Novgorod). The detection of the HF-induced AGWs was carried out in the Radiophysical Observatory located near Kharkiv City at a distance of about 960 km from the SURA. A coherent radar for vertical sounding, an ionosonde, and magnetometer chains were used in our measurements. The main results are the following (see [1-5]): 1. Infrasound oscillation trains with a period of 6 min are detected during periodic SURA heater turn-on and -off. Similar oscillation trains are detected after long time pumping, during periodic transmissions with a period of 20 s, as well as after pumping turn-off. The train recordings begin 28 - 54 min after the heater turn-on or -off, and the train propagation speeds are about 300 - 570 m/s, the value of which is close to the sound speed at upper atmospheric altitudes. The amplitude of the Doppler shift frequency is of 10 - 40 mHz, which fits to the 0.1 - 0.3% electron density disturbances at ionospheric altitudes. The amplitude of the infrasound oscillations depends on the SURA mode of operation and the state of the upper atmosphere and ionosphere. 2. High-power radio transmissions stimulate the generation (or enhancement) of waves at ionospheric altitudes in the range of internal gravity wave periods. The HF-induced waves propagate with speeds of 360 - 460 m/s and produce changes in electron density with amplitudes of 2 - 3%. The generation of such periodic perturbations is more preferable with periods of 10 - 60 minutes. Their features depend significantly on the heater mode of operation. It should be stressed that perturbation intensity increases when a pumping wave frequency approaches

  15. Environmental variability and acoustic signals: a multi-level approach in songbirds.

    PubMed

    Medina, Iliana; Francis, Clinton D

    2012-12-23

    Among songbirds, growing evidence suggests that acoustic adaptation of song traits occurs in response to habitat features. Despite extensive study, most research supporting acoustic adaptation has only considered acoustic traits averaged for species or populations, overlooking intraindividual variation of song traits, which may facilitate effective communication in heterogeneous and variable environments. Fewer studies have explicitly incorporated sexual selection, which, if strong, may favour variation across environments. Here, we evaluate the prevalence of acoustic adaptation among 44 species of songbirds by determining how environmental variability and sexual selection intensity are associated with song variability (intraindividual and intraspecific) and short-term song complexity. We show that variability in precipitation can explain short-term song complexity among taxonomically diverse songbirds, and that precipitation seasonality and the intensity of sexual selection are related to intraindividual song variation. Our results link song complexity to environmental variability, something previously found for mockingbirds (Family Mimidae). Perhaps more importantly, our results illustrate that individual variation in song traits may be shaped by both environmental variability and strength of sexual selection.

  16. Launch vehicle and power level impacts on electric GEO insertion

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.; Myers, Roger M.

    1996-01-01

    Solar Electric Propulsion (SEP) has been shown to increase net geosynchronous spacecraft mass when used for station keeping and final orbit insertion. The impact of launch vehicle selection and power level on the benefits of this approach were examined for 20 and 25 kW systems launched using the Ariane 5, Atlas IIAR, Long March, Proton, and Sea Launch vehicles. Two advanced on-board propulsion technologies, 5 kW ion and Hall thruster systems, were used to establish the relative merits of the technologies and launch vehicles. GaAs solar arrays were assumed. The analysis identifies the optimal starting orbits for the SEP orbit raising/plane changing while considering the impacts of radiation degradation in the Van Allen belts, shading, power degradation, and oblateness. This use of SEP to provide part of the orbit insertion results in net mass increases of 15 - 38% and 18 - 46% for one to two month trip times, respectively, over just using SEP for 15 years of north/south station keeping. SEP technology was shown to have a greater impact on net masses of launch vehicles with higher launch latitudes when avoidance of solar array and payload degradation is desired. This greater impact of SEP could help reduce the plane changing disadvantage of high latitude launch sites. Comparison with results for 10 and 15 kW systems show clear benefits of incremental increases in SEP power level, suggesting that an evolutionary approach to high power SEP for geosynchronous spacecraft is possible.

  17. Lake Erie water level study. Appendix E. Power. Final report

    SciTech Connect

    Not Available

    1981-07-01

    This appendix presents the results of the studies on the effects of limited regulation of Lake Erie on hydroelectric power generation. These studies were undertaken by the International Lake Erie Regulation Study Board. The Board was established by the International Joint Commission in 1977 to conduct the study as a result of the reference from the Governments of Canada and the United States. The purpose of the studies was to determine the economic effects of changes in levels and flows as a result of limited regulation of Lake Erie. This appendix contains the study results of the effect on the generation of hydroelectric power on the connecting channels of the Great Lakes and on the St. Lawrence River. The methodologies used in evaluating the effects of the various regulation plans indicate the benefits or losses to hydroelectric power generation in terms of energy and capacity resulting from changes in levels and flows. The methods used in the evaluation were those used in current economic studies by the power entities involved.

  18. Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO

    NASA Technical Reports Server (NTRS)

    Trout, Dawn H.; Stanley, James E.; Wahid, Parveen F.

    2011-01-01

    Evaluating the impact of radio frequency transmission in vehicle fairings is important to sensitive spacecraft. This paper employees the Multilevel Fast Multipole Method (MLFMM) feature of a commercial electromagnetic tool to model the fairing electromagnetic environment in the presence of an internal transmitter. This work is an extension of the perfect electric conductor model that was used to represent the bare aluminum internal fairing cavity. This fairing model includes typical acoustic blanketing commonly used in vehicle fairings. Representative material models within FEKO were successfully used to simulate the test case.

  19. A single-layer, planar, optofluidic switch powered by acoustically driven, oscillating microbubbles

    NASA Astrophysics Data System (ADS)

    Huang, Po-Hsun; Ian Lapsley, Michael; Ahmed, Daniel; Chen, Yuchao; Wang, Lin; Jun Huang, Tony

    2012-10-01

    Merging acoustofluidic mixing with optofluidic integration, we have demonstrated a single-layer, planar, optofluidic switch that is driven by acoustically excited oscillating microbubbles. The device was found to have a switching speed of 5 Hz, an insertion loss of 6.02 dB, and an extinction ratio of 28.48 dB. With its simplicity, low fluid consumption, and compatibility with other microfluidic devices, our design could lead to a line of inexpensive, yet effective optical switches for many lab-on-a-chip applications.

  20. Device for timing and power level setting for microwave applications

    NASA Astrophysics Data System (ADS)

    Ursu, M.-P.; Buidoş, T.

    2016-08-01

    Nowadays, the microwaves are widely used for various technological processes. The microwaves are emitted by magnetrons, which have strict requirements concerning power supplies for anode and filament cathodes, intensity of magnetic field, cooling and electromagnetic shielding. The magnetrons do not tolerate any alteration of their required voltages, currents and magnetic fields, which means that their output microwave power is fixed, so the only way to alter the power level is to use time-division, by turning the magnetron on and off by repetitive time patterns. In order to attain accurate and reproducible results, as well as correct and safe operation of the microwave device, all these requirements must be fulfilled. Safe, correct and reproducible operation of the microwave appliance can be achieved by means of a specially built electronic device, which ensures accurate and reproducible exposure times, interlocking of the commands and automatic switch off when abnormal operating conditions occur. This driving device, designed and realized during the completion of Mr.Ursu's doctoral thesis, consists of a quartz time-base, several programmable frequency and duration dividers, LED displays, sensors and interlocking gates. The active and passive electronic components are placed on custom-made PCB's, designed and made by means of computer-aided applications and machines. The driving commands of the electronic device are delivered to the magnetron power supplies by means of optic zero-passing relays. The inputs of the electronic driving device can sense the status of the microwave appliance. The user is able to enter the total exposure time, the division factor that sets the output power level and, as a novelty, the clock frequency of the time divider.

  1. Evaluation of Acoustic Doppler Current Profiler to Measure Discharge at New York Power Authority's Niagara Power Project, Niagara Falls, New York

    USGS Publications Warehouse

    Zajd, Henry J.

    2007-01-01

    The need for accurate real-time discharge in the International Niagara River hydro power system requires reliable, accurate and reproducible data. The U.S. Geological Survey has been widely using Acoustic Doppler Current Profilers (ADCP) to accurately measure discharge in riverine channels since the mid-1990s. The use of the ADCP to measure discharge has remained largely untested at hydroelectric-generation facilities such as the New York Power Authority's (NYPA) Niagara Power Project in Niagara Falls, N.Y. This facility has a large, engineered diversion channel with the capacity of high volume discharges in excess of 100,000 cubic feet per second (ft3/s). Facilities such as this could benefit from the use of an ADCP, if the ADCP discharge measurements prove to be more time effective and accurate than those obtained from the flow-calculation techniques that are currently used. Measurements of diversion flow by an ADCP in the 'Pant Leg' diversion channel at the Niagara Power Project were made on November 6, 7, and 8, 2006, and compared favorably (within 1 percent) with those obtained concurrently by a conventional Price-AA current-meter measurement during one of the ADCP measurement sessions. The mean discharge recorded during each 2-hour individual ADCP measurement session compared favorably with (3.5 to 6.8 percent greater than) the discharge values computed by the flow-calculation method presently in use by NYPA. The use of ADCP technology to measure discharge could ultimately permit increased power-generation efficiency at the NYPA Niagara Falls Power Project by providing improved predictions of the amount of water (and thus the power output) available.

  2. Impurity levels and power loading in the PDX tokamak with high power neutral beam injection

    SciTech Connect

    Fonck, R.J.; Bell, M.; Bol, K.

    1982-10-01

    The PDX tokamak provides an experimental facility for the direct comparison of various impurity control techniques under reactor-like conditions. Four neutral beam lines can inject up to 6 MW for 300 ms. Carbon rail limiter discharges have been used to test the effectiveness of perpendicular injection, but non-disruptive full power operation for > 100 ms is difficult without extensive conditioning. Initial tests of a toroidal bumper limiter indicate reduced power loading and roughly similar impurity levels compared to the carbon rail limiter discharges. Poloidal divertor discharges with up to 5 MW of injected power are cleaner than similar circular discharges, and the power is deposited in a remote divertor chamber. High density divertor operation indicates a reduction of impurity flow velocity in the divertor and enhanced recycling in the divertor region during neutral injection.

  3. The Acoustic Analogy: A Powerful Tool in Aeroacoustics with Emphasis on Jet Noise Prediction

    NASA Technical Reports Server (NTRS)

    Farassat, F.; Doty, Michael J.; Hunter, Craig A.

    2004-01-01

    The acoustic analogy introduced by Lighthill to study jet noise is now over 50 years old. In the present paper, Lighthill s Acoustic Analogy is revisited together with a brief evaluation of the state-of-the-art of the subject and an exploration of the possibility of further improvements in jet noise prediction from analytical methods, computational fluid dynamics (CFD) predictions, and measurement techniques. Experimental Particle Image Velocimetry (PIV) data is used both to evaluate turbulent statistics from Reynolds-averaged Navier-Stokes (RANS) CFD and to propose correlation models for the Lighthill stress tensor. The NASA Langley Jet3D code is used to study the effect of these models on jet noise prediction. From the analytical investigation, a retarded time correction is shown that improves, by approximately 8 dB, the over-prediction of aft-arc jet noise by Jet3D. In experimental investigation, the PIV data agree well with the CFD mean flow predictions, with room for improvement in Reynolds stress predictions. Initial modifications, suggested by the PIV data, to the form of the Jet3D correlation model showed no noticeable improvements in jet noise prediction.

  4. Acoustic neuroma

    MedlinePlus

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

  5. A seismic field test with a Low-level Acoustic Combustion Source and Pseudo-Noise codes

    NASA Astrophysics Data System (ADS)

    Askeland, Bjørn; Ruud, Bent Ole; Hobæk, Halvor; Mjelde, Rolf

    2009-01-01

    The Low-level Acoustic Combustion Source (LACS) which can fire its pulses at a high rate, has been tested successfully as a seismic marine source on shallow ice-age sediments in Byfjorden at Bergen, Norway. Pseudo-Noise pulsed signals with spiky autocorrelation functions were used to detect the sediments. Each transmitted sequence lasted 10 s and contained 43 pulses. While correlation gave a blurry result, deconvolution between the near-field recordings and the streamer recordings gave a clear seismic section. Compared to the section acquired with single air-gun shots along the same profile, the LACS gave a more clear presentation of the sediments and basement.

  6. Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO

    NASA Technical Reports Server (NTRS)

    Trout, Dawn H.; Stanley, James E.; Wahid, Parveen F.

    2011-01-01

    Evaluating the impact of radio frequency transmission in vehicle fairings is important to electromagnetically sensitive spacecraft. This study employs the multilevel fast multipole method (MLFMM) from a commercial electromagnetic tool, FEKO, to model the fairing electromagnetic environment in the presence of an internal transmitter with improved accuracy over industry applied techniques. This fairing model includes material properties representative of acoustic blanketing commonly used in vehicles. Equivalent surface material models within FEKO were successfully applied to simulate the test case. Finally, a simplified model is presented using Nicholson Ross Weir derived blanket material properties. These properties are implemented with the coated metal option to reduce the model to one layer within the accuracy of the original three layer simulation.

  7. The percentage of the population exposed to harmful acoustic pollution levels resulting from vehicular traffic in the Hospital' area of Turin.

    PubMed

    Giovinetto, R; Roletti, S; Saporiti, F

    2004-01-01

    This paper presents the methodology and the main results of a study that has as its principal aim, the experimental identification the application and the quantification of the sustainable indicator 'Percentage of the population exposed to acoustic pollution levels' in the 'Hospital' area of Turin. The investigation of this indicator was prompted by the province of Turin's previous categorisation as 'Lead City' in the project 'Towards a support description at local the level--European Community Indicators'. Alongside, the process of experimenting, applying and quantifying the sustainable indicator--and as a logical fit with what was foreseen by the Italian normative regulation on protection against environmental acoustic pollution--the study supplies the base elements to analyse the environmental acoustic climate conditions in an important area of the city and defines the interaction tools that are the environmental indicators for the town council's future Acoustic Restoration Plan (PRA).

  8. The design of Helmholtz resonator based acoustic lenses by using the symmetric Multi-Level Wave Based Method and genetic algorithms

    NASA Astrophysics Data System (ADS)

    Atak, Onur; Huybrechs, Daan; Pluymers, Bert; Desmet, Wim

    2014-07-01

    Sonic crystals can be used as acoustic lenses in certain frequencies and the design of such systems by creating vacancies and using genetic algorithms has been proven to be an effective method. So far, rigid cylinders have been used to create such acoustic lens designs. On the other hand, it has been proven that Helmholtz resonators can be used to construct acoustic lenses with higher refraction index as compared to rigid cylinders, especially in low frequencies by utilizing their local resonances. In this paper, these two concepts are combined to design acoustic lenses that are based on Helmholtz resonators. The Multi-Level Wave Based Method is used as the prediction method. The benefits of the method in the context of design procedure are demonstrated. In addition, symmetric boundary conditions are derived for more efficient calculations. The acoustic lens designs that use Helmholtz resonators are compared with the acoustic lens designs that use rigid cylinders. It is shown that using Helmholtz resonator based sonic crystals leads to better acoustic lens designs, especially at the low frequencies where the local resonances are pronounced.

  9. Technical basis for staffing levels at nuclear power plants

    SciTech Connect

    Shurberg, D.A.; Haber, S.B.; Morisseau, D.

    1995-04-01

    The objective of this project is to provide a technical basis for the establishment of criteria for minimum staffing levels of licensed and non-licensed NPP shift personnel. Minimum staffing levels for the purpose of this study, are defined as those necessary for successful accomplishment of all safety and additional functions that must be performed in order for the licensee to meet applicable regulatory requirements. This project involves a multi-faceted approach to the investigation of the issue. Relevant NRC documentation was identified and reviewed. Using the information obtained from this documentation review, a test plan was developed to aid in the collection of further information regarding the adequacy of current shift staffing levels. The test plan addresses three different activities to be conducted to provide information to the NRC for use in the assessment of current minimum staffing levels. The first activity is collection of data related to industry shift staffing practices through site visits to seven nuclear power plants. The second activity is a simulator study, which will use licensed operator crews responding to a simulated event, under two different staffing levels. Finally, workload models will be constructed for both licensed and non-licensed personnel, using a priori knowledge of the simulator scenarios with data resulting from one of the staffing levels studied in the simulator, and the data collected from the site visits. The model will then be validated against the data obtained from the second staffing level studied in the simulator. The validated model can then be used to study the impact of changing staffing-related variables on the plant shift crew`s ability to effectively mitigate an event.

  10. Pseudopotential approach for dust acoustic solitary waves in dusty plasmas with kappa-distributed ions and electrons and dust grains having power law size distribution

    SciTech Connect

    Banerjee, Gadadhar; Maitra, Sarit

    2015-04-15

    Sagdeev's pseudopotential method is used to study small as well as arbitrary amplitude dust acoustic solitons in a dusty plasma with kappa distributed electrons and ions with dust grains having power law size distribution. The existence of potential well solitons has been shown for suitable parametric region. The criterion for existence of soliton is derived in terms of upper and lower limit for Mach numbers. The numerical results show that the size distribution can affect the existence as well as the propagation characteristics of the dust acoustic solitons. The effect of kappa distribution is also highlighted.

  11. Indoor acoustic gain design

    NASA Astrophysics Data System (ADS)

    Concha-Abarca, Justo Andres

    2002-11-01

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

  12. Analysis and modeling of 255 source levels of merchant ships from an acoustic observatory along St. Lawrence Seaway.

    PubMed

    Simard, Yvan; Roy, Nathalie; Gervaise, Cédric; Giard, Samuel

    2016-09-01

    An ensemble of 255 spectral source levels (SSLs) of merchant ships were measured with an opportunistic seaway acoustic observatory adhering to the American National Standards Institute/Acoustical Society of America S12.64-2009 standard as much as possible, and deployed in the 350-m deep lower St. Lawrence Seaway in eastern Canada. The estimated SSLs were sensitive to the transmission loss model. The best transmission loss model at the three measuring depths was an empirical in situ function for ranges larger than 300 m, fused with estimates from a wavenumber integration propagation model fed with inverted local geoacoustic properties for [300 to 1 m] ranges. Resulting SSLs still showed a high variability. Uni- and multi-variate analyses showed weak intermingled relations with ship type, length, breadth, draught, speed, age, and other variables. Cluster analyses distinguished six different SSL patterns, which did not correspond to distinctive physical characteristics of the ships. The broadband [20-500 Hz] source levels varied by 30 dB or more within all four 50-m length categories. Common SSL models based on frequency, length and speed failed to unbiasly replicate the observations. This article presents unbiased SSL models that explain 75%-88% of the variance using frequency, ship speed, and three other automatic identification system ship characteristics.

  13. On the variations of acoustic absorption peak with particle velocity in micro-perforated panels at high level of excitation.

    PubMed

    Tayong, Rostand; Dupont, Thomas; Leclaire, Philippe

    2010-05-01

    The acoustic behavior of micro-perforated panels (MPP) is studied theoretically and experimentally at high level of pressure excitation. A model based on Forchheimer's regime of flow velocity in the perforations is proposed. This model is valid at relatively high Reynolds numbers and low Mach numbers. The experimental method consists in measuring the acoustical pressure at three different positions in an impedance tube, the two measurement positions usually considered in an impedance tube and one measurement in the vicinity of the rear surface of the MPP. The impedance tube is equipped with a pressure driver instead of the usual loudspeaker and capable of delivering a high sound pressure level up to 160 dB. MPP specimens made out of steel, dural and polypropylene were tested. Measurements using random noise or sinusoidal excitation in a frequency range between 200 and 1600 Hz were carried out on MPPs backed by air cavities. It was observed that the maximum of absorption can be a positive or a negative function of the flow velocity in the perforations. This suggests the existence of a maximum of absorption as a function of flow velocity. This behavior was predicted by the model and confirmed experimentally.

  14. Acoustic Noise Levels of Dental Equipments and Its Association with Fear and Annoyance Levels among Patients Attending Different Dental Clinic Setups in Jaipur, India

    PubMed Central

    Ganta, Shravani; Nagaraj, Anup; Pareek, Sonia; Atri, Mansi; Singh, Kushpal; Sidiq, Mohsin

    2014-01-01

    Background: Noise is a source of pervasive occupational hazard for practicing dentists and the patients. The sources of dental sounds by various dental equipments can pose as a potential hazard to hearing system and add to the annoyance levels of the patients. The aim of the study was to analyze the noise levels from various equipments and evaluate the effect of acoustic noise stimulus on dental fear and annoyance levels among patients attending different dental clinic setups in Jaipur, India. Methodology: The sampling frame comprised of 180 patients, which included 90 patients attending 10 different private clinics and 90 patients attending a Dental College in Jaipur. The levels of Acoustic Noise Stimulus originating from different equipments were determined using a precision sound level meter/decibulometer. Dental fear among patients was measured using Dental Fear Scale (DFS). Results: Statistical analysis was performed using chi square test and unpaired t-test. The mean background noise levels were found to be maximum in the pre-clinical setup/ laboratory areas (69.23+2.20). Females and the patients attending dental college setup encountered more fear on seeing the drill as compared to the patients attending private clinics (p<0.001). Conclusion: The sources of dental sounds can pose as a potential hazard to hearing system. It was analyzed that the environment in the clinics can directly have an effect on the fear and annoyance levels of patients. Hence it is necessary control the noise from various dental equipments to reduce the fear of patients from visiting a dental clinic. PMID:24959512

  15. Magnetic resonance acoustic radiation force imaging.

    PubMed

    McDannold, Nathan; Maier, Stephan E

    2008-08-01

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

  16. Low power underwater acoustic DPSK detection: Theoretical prediction and experimental results

    NASA Astrophysics Data System (ADS)

    Dunne, Andrew

    This thesis presents two methods of analyzing the effectiveness of a prototype differential phase-shift keying (DPSK) detection circuit. The first method is to make modifications to the existing hardware to reliably output and record the cross-correlation values of the DPSK detection process. The second method is to write a MATLAB detection algorithm which accurately simulates the detection results of the hardware system without the need of any electronics. These two systems were tested and verified with a bench test using computer generated DPSK signals. The hardware system was tested using real acoustic data from shallow and deep water at-sea tests to determine the effectiveness of the DPSK detection circuit in different ocean environments. The hydrophone signals from the tests were recorded so that the cross-correlation values could be verified using the MATLAB detector. As a result of this study, these two systems provided more insight into how well the DPSK detection prototype works and helped to identify ways of improving the detection reliability and overall performance of the prototype DPSK detection circuit.

  17. 2 kHz high power smart transducer for acoustic sub-bottom profiling applications

    NASA Astrophysics Data System (ADS)

    Sathishkumar, R.

    2013-09-01

    In this study, a 2 kHz Tonpilz projector was designed using a Terfenol-D and modeled in ATILA. For the purpose of modeling studies, it has been determined that a radiating head mass exhibits better transmitting current response (TCR) at 136 mm diameter, where the resonance occurs at 2.4 kHz and the peak value of 118 dB re 1 μPa/A at 1 m occurs at 12 kHz. Also bolt at a 46 mm distance from the center of the head mass offers resonance at 2.4 kHz, and the peak value of 115.3 dB re 1 μPa/A at 1m occurs at 11.5 kHz. This optimized design is fabricated and molded with polyurethane of 3 mm thickness. The prototype was tested at the Acoustic Test Facility (ATF) of National Institute of Ocean Technology (NIOT) for its underwater performances. Based on the result, the fundamental resonance was determined to be 2.18 kHz and the peak value of TCR of 182 dB re 1 μPa/A at 1m occurs at 14 kHz. The maximum value of the RS was found to be -190 dB re 1V/μPa at 1m at a frequency of 2.1 kHz.

  18. Ultrathin, rollable, paper-based triboelectric nanogenerator for acoustic energy harvesting and self-powered sound recording.

    PubMed

    Fan, Xing; Chen, Jun; Yang, Jin; Bai, Peng; Li, Zhaoling; Wang, Zhong Lin

    2015-04-28

    A 125 μm thickness, rollable, paper-based triboelectric nanogenerator (TENG) has been developed for harvesting sound wave energy, which is capable of delivering a maximum power density of 121 mW/m(2) and 968 W/m(3) under a sound pressure of 117 dBSPL. The TENG is designed in the contact-separation mode using membranes that have rationally designed holes at one side. The TENG can be implemented onto a commercial cell phone for acoustic energy harvesting from human talking; the electricity generated can be used to charge a capacitor at a rate of 0.144 V/s. Additionally, owing to the superior advantages of a broad working bandwidth, thin structure, and flexibility, a self-powered microphone for sound recording with rolled structure is demonstrated for all-sound recording without an angular dependence. The concept and design presented in this work can be extensively applied to a variety of other circumstances for either energy-harvesting or sensing purposes, for example, wearable and flexible electronics, military surveillance, jet engine noise reduction, low-cost implantable human ear, and wireless technology applications.

  19. A k-space Green's function solution for acoustic initial value problems in homogeneous media with power law absorption.

    PubMed

    Treeby, Bradley E; Cox, B T

    2011-06-01

    An efficient Green's function solution for acoustic initial value problems in homogeneous media with power law absorption is derived. The solution is based on the homogeneous wave equation for lossless media with two additional terms. These terms are dependent on the fractional Laplacian and separately account for power law absorption and dispersion. Given initial conditions for the pressure and its temporal derivative, the solution allows the pressure field for any time t>0 to be calculated in a single step using the Fourier transform and an exact k-space time propagator. For regularly spaced Cartesian grids, the former can be computed efficiently using the fast Fourier transform. Because no time stepping is required, the solution facilitates the efficient computation of the pressure field in one, two, or three dimensions without stability constraints. Several computational aspects of the solution are discussed, including the effect of using a truncated Fourier series to represent discrete initial conditions, the use of smoothing, and the properties of the encapsulated absorption and dispersion.

  20. Influence of ultrasound power on acoustic streaming and micro-bubbles formations in a low frequency sono-reactor: mathematical and 3D computational simulation.

    PubMed

    Sajjadi, Baharak; Raman, Abdul Aziz Abdul; Ibrahim, Shaliza

    2015-05-01

    This paper aims at investigating the influence of ultrasound power amplitude on liquid behaviour in a low-frequency (24 kHz) sono-reactor. Three types of analysis were employed: (i) mechanical analysis of micro-bubbles formation and their activities/characteristics using mathematical modelling. (ii) Numerical analysis of acoustic streaming, fluid flow pattern, volume fraction of micro-bubbles and turbulence using 3D CFD simulation. (iii) Practical analysis of fluid flow pattern and acoustic streaming under ultrasound irradiation using Particle Image Velocimetry (PIV). In mathematical modelling, a lone micro bubble generated under power ultrasound irradiation was mechanistically analysed. Its characteristics were illustrated as a function of bubble radius, internal temperature and pressure (hot spot conditions) and oscillation (pulsation) velocity. The results showed that ultrasound power significantly affected the conditions of hotspots and bubbles oscillation velocity. From the CFD results, it was observed that the total volume of the micro-bubbles increased by about 4.95% with each 100 W-increase in power amplitude. Furthermore, velocity of acoustic streaming increased from 29 to 119 cm/s as power increased, which was in good agreement with the PIV analysis.

  1. Efficient two-level cryogenic power distribution system

    NASA Astrophysics Data System (ADS)

    Mueller, O. M.; Mueller, E. K.

    2002-05-01

    The availability of new technologies such as high-temperature superconducting (HTS) cables, high-voltage, high-speed semiconductor switches, and cryogenic power conversion suggests that one considers how these technologies can be combined and applied effectively to provide a more efficient energy distribution system. The present-day 60 Hz concept is, after all, a century old. Advantages can be obtained by combining DC and high-frequency AC technologies. DC transmission solves the problem of AC losses in HTS cables and high-frequency switching techniques reduce size, weight and cost. This paper proposes and discusses a distribution system based on two DC voltage levels (˜4 kVDC/650 VDC) interconnected with DC/DC converters using high-voltage insulated-gate bipolar transistors (HV-IGBT's), integrated gate-commutated thyristors (IGCT's), or MOS-controlled turn-off thyristors (MTO's) operated at cryogenic temperatures. Cryo-MOSFET DC/AC inverters provide the 60 Hz, 240/120 VAC user voltages. HTS cables supply power as well as the cooling fluid liquid nitrogen (LN2). The load shedding properties of such a system based on the use of LN2 are evaluated. The proposed concept is suitable for city blocks with many high-rise buildings. It provides an increase in efficiency and therefore contributes to the reduction of global warming.

  2. Temporal variations in Global Seismic Stations ambient noise power levels

    USGS Publications Warehouse

    Ringler, A.T.; Gee, L.S.; Hutt, C.R.; McNamara, D.E.

    2010-01-01

    Recent concerns about time-dependent response changes in broadband seismometers have motivated the need for methods to monitor sensor health at Global Seismographic Network (GSN) stations. We present two new methods for monitoring temporal changes in data quality and instrument response transfer functions that are independent of Earth seismic velocity and attenuation models by comparing power levels against different baseline values. Our methods can resolve changes in both horizontal and vertical components in a broad range of periods (∼0.05 to 1,000 seconds) in near real time. In this report, we compare our methods with existing techniques and demonstrate how to resolve instrument response changes in long-period data (>100 seconds) as well as in the microseism bands (5 to 20 seconds).

  3. Modeling power law absorption and dispersion for acoustic propagation using the fractional Laplacian.

    PubMed

    Treeby, Bradley E; Cox, B T

    2010-05-01

    The efficient simulation of wave propagation through lossy media in which the absorption follows a frequency power law has many important applications in biomedical ultrasonics. Previous wave equations which use time-domain fractional operators require the storage of the complete pressure field at previous time steps (such operators are convolution based). This makes them unsuitable for many three-dimensional problems of interest. Here, a wave equation that utilizes two lossy derivative operators based on the fractional Laplacian is derived. These operators account separately for the required power law absorption and dispersion and can be efficiently incorporated into Fourier based pseudospectral and k-space methods without the increase in memory required by their time-domain fractional counterparts. A framework for encoding the developed wave equation using three coupled first-order constitutive equations is discussed, and the model is demonstrated through several one-, two-, and three-dimensional simulations.

  4. A computational modeling approach of the jet-like acoustic streaming and heat generation induced by low frequency high power ultrasonic horn reactors.

    PubMed

    Trujillo, Francisco Javier; Knoerzer, Kai

    2011-11-01

    High power ultrasound reactors have gained a lot of interest in the food industry given the effects that can arise from ultrasonic-induced cavitation in liquid foods. However, most of the new food processing developments have been based on empirical approaches. Thus, there is a need for mathematical models which help to understand, optimize, and scale up ultrasonic reactors. In this work, a computational fluid dynamics (CFD) model was developed to predict the acoustic streaming and induced heat generated by an ultrasonic horn reactor. In the model it is assumed that the horn tip is a fluid inlet, where a turbulent jet flow is injected into the vessel. The hydrodynamic momentum rate of the incoming jet is assumed to be equal to the total acoustic momentum rate emitted by the acoustic power source. CFD velocity predictions show excellent agreement with the experimental data for power densities higher than W(0)/V ≥ 25kWm(-3). This model successfully describes hydrodynamic fields (streaming) generated by low-frequency-high-power ultrasound.

  5. Determining the energy level of laser induced cracks in alumina substrate via acoustic emission

    NASA Astrophysics Data System (ADS)

    Aslan, M.; Beausang, J.; Tittmann, B. R.

    2000-05-01

    The electronics industry relies on alumina (Al2O3) substrates to isolate, electrically and thermally, the computer chip from the rest of the circuit. In order to improve the manufacturing process of these chips, it is desirable to machine the substrates with a laser rather than the conventional techniques. Unfortunately, the high thermal stresses due to the intensity of the laser cause the extremely brittle ceramic to crack and sometimes fail. The purpose of this research was to study the response of a thin alumina ceramic substrate while it was slowly drilled with a CO2 laser. The energy released by the cracks were measured in-situ via acoustic emission (AE). AE is ideal for capturing the stress wave emissions emitted from the cracking events, while the ceramic is being drilled with the laser. One of the components of the AE system, the Digital Wave Fracture Wave Detector™, recorded the AE signals emitted during slow laser drilling of the alumina plates. Total crack length was correlated with total AE energy emitted, and these data were compared in two experiments, slow drilling and crack extension. A fundamental trend of increasing AE energy with increasing crack length was verified in these experiments.—This work has been partially supported by National Science Foundation Grant #CMS-9634744.

  6. Integrated Architectural Level Power-Performance Modeling Toolkit

    DTIC Science & Technology

    2004-08-20

    laptop) systems. We utilize the MET/ Turandot toolkit originally developed at IBM TJ Watson Research Center as the underlying PowerPC...microarchitecture performance simulator [3]. Turandot is flexible enough to model a broad range of microarchitectures and has undergone extensive validation [3...In addition, Turandot has been augmented with power models to explore power-performance tradeoffs in an internal IBM tool called PowerTimer [4

  7. Space Shuttle Main Engine Off-Nominal Low Power Level Operation

    NASA Technical Reports Server (NTRS)

    Bradley, Michael

    1997-01-01

    This paper describes Rocketdyne's successful analysis and demonstration of the Space Shuttle Main Engine (SSME) operation at off-nominal power levels during Reusable Launch Vehicle (RLV) evaluation tests. The nominal power level range for the SSME is from 65% rated power level (RPL) to 109% RPL. Off-nominal power levels incrementally demonstrated were: 17% RPL, 22% RPL, 27% RPL, 40% RPL, 45% RPL, and 50% RPL. Additional achievements during low power operation included: use of a hydrostatic bearing High Pressure Oxidizer Turbopump (HPOTP), nominal High Pressure Fuel Turbopump (HPFTP) first rotor critical speed operation, combustion stability at low power levels, and refined definition of nozzle flow separation heat loads.

  8. Acoustic emission feedback control for control of boiling in a microwave oven

    SciTech Connect

    White, T.L.

    1991-02-26

    This patent describes an acoustic emission based feedback system for controlling the boiling level of a liquid medium in a microwave oven. The acoustic emissions from the medium correlated with surface boiling is used to generate a feedback control signal proportional to the level of boiling of the medium. This signal is applied to a power controller to automatically and continuously vary the power applied to the oven to control the boiling at a selected level.

  9. Acoustic emission feedback control for control of boiling in a microwave oven

    SciTech Connect

    White, T.L.

    1990-05-02

    An acoustic emission based feedback system for controlling the boiling level of a liquid medium in a microwave oven is provided. The acoustic emissions from the medium correlated with surface boiling is used to generate a feedback control signal proportional to the level of boiling of the medium. This signal is applied to a power controller to automatically and continuously vary the power applied to the oven to control the boiling at a selected level. 2 figs.

  10. Acoustic emission feedback control for control of boiling in a microwave oven

    DOEpatents

    White, Terry L.

    1991-01-01

    An acoustic emission based feedback system for controlling the boiling level of a liquid medium in a microwave oven is provided. The acoustic emissions from the medium correlated with surface boiling is used to generate a feedback control signal proportional to the level of boiling of the medium. This signal is applied to a power controller to automatically and continuoulsly vary the power applied to the oven to control the boiling at a selected level.

  11. NASA powered lift facility internally generated noise and its transmission to the acoustic far field

    NASA Technical Reports Server (NTRS)

    Huff, Ronald G.

    1988-01-01

    Noise tests of NASA Lewis Research Center's Powered Lift Facility (PLF) were performed to determine the frequency content of the internally generated noise that reaches the far field. The sources of the internally generated noise are the burner, elbows, valves, and flow turbulence. Tests over a range of nozzle pressure ratios from 1.2 to 3.5 using coherence analysis revealed that low frequency noise below 1200 Hz is transmitted through the nozzle. Broad banded peaks at 240 and 640 Hz were found in the transmitted noise. Aeroacoustic excitation effects are possible in this frequency range. The internal noise creates a noise floor that limits the amount of jet noise suppression that can be measured on the PLF and similar facilities.

  12. A Power Analysis and Recommended Study Design to Directly Detect Population Level Consequences of Acoustic Disturbance

    DTIC Science & Technology

    2015-09-30

    stable while use of SOAR declines) 3) annual survival rates 4) productivity (e.g., reproductive success) We will consult the PCAD project as one...be useful for monitoring beaked whale population health? For example, biopsy sampling could provide data on population sex ratio and reproductive

  13. The Development of the Acoustic Design of NASA Glenn Research Center's New Reverberant Acoustic Test Facility

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Mark E.; Hozman, Aron D.; McNelis, Anne M.

    2011-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC s Plum Brook Station in Sandusky, Ohio. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA s space exploration program. The large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 ft3 in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world s known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada s acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic design and subsequent on-going construction.

  14. The Development of the Acoustic Design of NASA Glenn Research Center's New Reverberant Acoustic Test Facility

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Mark E.; Hozman, Aron D.; McNelis, Anne M.

    2011-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA s space exploration program. The large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 ft3 in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world s known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada s acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama, USA. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic design and subsequent on-going construction.

  15. Partial discharge localization in power transformers based on the sequential quadratic programming-genetic algorithm adopting acoustic emission techniques

    NASA Astrophysics Data System (ADS)

    Liu, Hua-Long; Liu, Hua-Dong

    2014-10-01

    Partial discharge (PD) in power transformers is one of the prime reasons resulting in insulation degradation and power faults. Hence, it is of great importance to study the techniques of the detection and localization of PD in theory and practice. The detection and localization of PD employing acoustic emission (AE) techniques, as a kind of non-destructive testing, plus due to the advantages of powerful capability of locating and high precision, have been paid more and more attention. The localization algorithm is the key factor to decide the localization accuracy in AE localization of PD. Many kinds of localization algorithms exist for the PD source localization adopting AE techniques including intelligent and non-intelligent algorithms. However, the existed algorithms possess some defects such as the premature convergence phenomenon, poor local optimization ability and unsuitability for the field applications. To overcome the poor local optimization ability and easily caused premature convergence phenomenon of the fundamental genetic algorithm (GA), a new kind of improved GA is proposed, namely the sequence quadratic programming-genetic algorithm (SQP-GA). For the hybrid optimization algorithm, SQP-GA, the sequence quadratic programming (SQP) algorithm which is used as a basic operator is integrated into the fundamental GA, so the local searching ability of the fundamental GA is improved effectively and the premature convergence phenomenon is overcome. Experimental results of the numerical simulations of benchmark functions show that the hybrid optimization algorithm, SQP-GA, is better than the fundamental GA in the convergence speed and optimization precision, and the proposed algorithm in this paper has outstanding optimization effect. At the same time, the presented SQP-GA in the paper is applied to solve the ultrasonic localization problem of PD in transformers, then the ultrasonic localization method of PD in transformers based on the SQP-GA is proposed. And

  16. A point acoustic device based on aluminum nanowires.

    PubMed

    Xie, Qian-Yi; Ju, Zhen-Yi; Tian, He; Xue, Qing-Tang; Chen, Yuan-Quan; Tao, Lu-Qi; Mohammad, Mohammad Ali; Zhang, Xue-Yue; Yang, Yi; Ren, Tian-Ling

    2016-03-14

    A point Electrical Thermal Acoustic (ETA) device based on aluminum nanowire contacts is designed and fabricated. Interdigitated structural aluminum nanowires are released from the substrate by Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE). By releasing the interdigitated structure, the nanowires contact each other at approximately 1 mm above the wafer, forming a Point Contact Structure (PCS). It is found that the PCS acoustic device realizes high efficiency when a biased AC signal is applied. The PCS acoustic device reaches a sound pressure level as high as 67 dB at a distance of 1 cm with 74 mW AC input. The power spectrum is flat, ranging from 2 kHz to 20 kHz with a less than ±3 dB fluctuation. The highest normalized Sound Pressure Level (SPL) of the point contact structure acoustic device is 18 dB higher than the suspended aluminum wire acoustic device. Comparisons between the PCS acoustic device and the Suspended Aluminum Nanowire (SAN) acoustic device illustrate that the PCS acoustic device has a flatter power spectrum within the 20 kHz range, and enhances the SPL at a lower frequency. Enhancing the response at lower frequencies is extremely useful, which may enable earphone and loudspeaker applications within the frequency range of the human ear with the help of pulse density modulation.

  17. The effect of the coupling between the top plate and the fingerboard on the acoustic power radiated by a classical guitar (L).

    PubMed

    García-Mayén, Héctor; Santillán, Arturo

    2011-03-01

    An experimental investigation on the coupling between the fingerboard and the top plate of a classical guitar at low frequencies is presented. The study was carried out using a finished top plate under fixed boundary conditions and a commercial guitar. Radiated sound power was determined in one-third octave bands up to the band of 1 kHz based on measurements of sound intensity. The results provide evidence that the way in which the fingerboard and top plate are coupled is not a relevant factor in the radiated acoustic power of the classical guitar in the studied frequency range.

  18. Capabilities, Design, Construction and Commissioning of New Vibration, Acoustic, and Electromagnetic Capabilities Added to the World's Largest Thermal Vacuum Chamber at NASA's Space Power Facility

    NASA Technical Reports Server (NTRS)

    Motil, Susan M.; Ludwiczak, Damian R.; Carek, Gerald A.; Sorge, Richard N.; Free, James M.; Cikanek, Harry A., III

    2011-01-01

    NASA s human space exploration plans developed under the Exploration System Architecture Studies in 2005 included a Crew Exploration Vehicle launched on an Ares I launch vehicle. The mass of the Crew Exploration Vehicle and trajectory of the Ares I coupled with the need to be able to abort across a large percentage of the trajectory generated unprecedented testing requirements. A future lunar lander added to projected test requirements. In 2006, the basic test plan for Orion was developed. It included several types of environment tests typical of spacecraft development programs. These included thermal-vacuum, electromagnetic interference, mechanical vibration, and acoustic tests. Because of the size of the vehicle and unprecedented acoustics, NASA conducted an extensive assessment of options for testing, and as result, chose to augment the Space Power Facility at NASA Plum Brook Station, of the John H. Glenn Research Center to provide the needed test capabilities. The augmentation included designing and building the World s highest mass capable vibration table, the highest power large acoustic chamber, and adaptation of the existing World s largest thermal vacuum chamber as a reverberant electromagnetic interference test chamber. These augmentations were accomplished from 2007 through early 2011. Acceptance testing began in Spring 2011 and will be completed in the Fall of 2011. This paper provides an overview of the capabilities, design, construction and acceptance of this extraordinary facility.

  19. Helicopter far-field acoustic levels as a function of reduced main-rotor advancing blade-tip Mach number

    NASA Technical Reports Server (NTRS)

    Mueller, Arnold W.; Smith, Charles D.; Lemasurier, Philip

    1990-01-01

    During the design of a helicopter, the weight, engine, rotor speed, and rotor geometry are given significant attention when considering the specific operations for which the helicopter will be used. However, the noise radiated from the helicopter and its relationship to the design variables is currently not well modeled with only a limited set of full-scale field test data to study. In general, limited field data have shown that reduced main-rotor advancing blade-tip Mach numbers result in reduced far-field noise levels. The status of a recent helicopter noise research project is reviewed. It is designed to provide flight experimental data which may be used to further understand helicopter main-rotor advancing blade-tip Mach number effects on far-field acoustic levels. Preliminary results are presented relative to tests conducted with a Sikorsky S-76A helicopter operating with both the rotor speed and the flight speed as the control variable. The rotor speed was operated within the range of 107 to 90 percent NR at nominal forward speeds of 35, 100, and 155 knots.

  20. Comparative measurements of the level of turbulence atmosphere by optical and acoustic devices

    NASA Astrophysics Data System (ADS)

    Lukin, V. P.; Botugina, N. N.; Gladkih, V. A.; Emaleev, O. N.; Konyaev, P. A.; Odintsov, S. L.; Torgaev, A. V.

    2014-11-01

    The complex measurements of level of atmospheric turbulence are conducted by the differential measurement device of turbulence (DMT), wave-front sensor (WFS), and also by ultrasonic weather-stations. Daytime measurements of structure parameters of refractive index of atmospheric turbulence carried out on horizontal optical paths on the Base Experimental Complex (BEC) of V.E. Zuev Institute of Atmospheric Optics SB RAS (IOA). A comparative analysis over of the got results is brought.

  1. A comparison of Brayton and Stirling space nuclear power systems for power levels from 1 kilowatt to 10 megawatts

    NASA Astrophysics Data System (ADS)

    Mason, Lee S.

    2001-02-01

    An analytical study was conducted to assess the performance and mass of Brayton and Stirling nuclear power systems for a wide range of future NASA space exploration missions. The power levels and design concepts were based on three different mission classes. Isotope systems, with power levels from 1 to 10 kilowatts, were considered for planetary surface rovers and robotic science. Reactor power systems for planetary surface outposts and bases were evaluated from 10 to 500 kilowatts. Finally, reactor power systems in the range from 100 kilowatts to 10 megawatts were assessed for advanced propulsion applications. The analysis also examined the effect of advanced component technology on system performance. The advanced technologies included high temperature materials, lightweight radiators, and high voltage power management and distribution. .

  2. A Comparison of Brayton and Stirling Space Nuclear Power Systems for Power Levels from 1 Kilowatt to 10 Megawatts

    NASA Technical Reports Server (NTRS)

    Mason, Lee S.

    2000-01-01

    An analytical study was conducted to assess the performance and mass of Brayton and Stirling nuclear power systems for a wide range of future NASA space exploration missions. The power levels and design concepts were based on three different mission classes. Isotope systems, with power levels from 1 to 10 kW, were considered for planetary surface rovers and robotic science. Reactor power systems for planetary surface outposts and bases were evaluated from 10 to 500 kW. Finally, reactor power systems in the range from 100 kW to 10 mW were assessed for advanced propulsion applications. The analysis also examined the effect of advanced component technology on system performance. The advanced technologies included high temperature materials, lightweight radiators, and high voltage power management and distribution.

  3. Cognitive Aspects of Power in a Two-Level Game

    NASA Astrophysics Data System (ADS)

    Juvina, Ion; Lebiere, Christian; Martin, Jolie; Gonzalez, Cleotilde

    The Intergroup Prisoner's Dilemma with Intragroup Power Dynamics (IPD^2) is a new game paradigm for studying human behavior in conflict situations. IPD^2 adds the concept of intragroup power to an intergroup version of the standard Iterated Prisoner's Dilemma game. We conducted an exploratory laboratory study in which individual human participants played the game against computer strategies of various complexities. We also developed a cognitive model of human decision making in this game. The model was run in place of the human participant under the same conditions as in the laboratory study. Results from the human study and the model simulations are presented and discussed, emphasizing the value of including intragroup power in game theoretic models of conflict.

  4. Ion Thruster Power Levels Extended by a Factor of 10

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.

    2004-01-01

    In response to two NASA Office of Space Science initiatives, the NASA Glenn Research Center is now developing a 7-kW-class xenon ion thruster system for near-term solar-powered spacecraft and a 25-kW ion engine for nuclear-electric spacecraft. The 7-kW ion thruster and power processor can be throttled down to 1 kW and are applicable to 25-kW flagship missions to the outer planets, asteroids, and comets. This propulsion system was scaled up from the 2.5-kW ion thruster and power processor that was developed successfully by Glenn, Boeing, the Jet Propulsion Laboratory (JPL), and Spectrum Astro for the Deep Space 1 spacecraft. The 7-kW ion thruster system is being developed under NASA's Evolutionary Xenon Thruster (NEXT) project, which includes partners from JPL, Aerojet, Boeing, the University of Michigan, and Colorado State University.

  5. Acoustic Neuroma

    MedlinePlus

    ... search IRSA's site Unique Hits since January 2003 Acoustic Neuroma Click Here for Acoustic Neuroma Practice Guideline ... to microsurgery. One doctor's story of having an acoustic neuroma In August 1991, Dr. Thomas F. Morgan ...

  6. Module-Level Power Converters For Parallel Connected Photovoltaic Arrays

    DTIC Science & Technology

    2012-01-01

    Output Voltage Io Output Current Po Output Power fsw Switching Frequency η Efficiency α Regulation Bac Operating Flux Density Ku Window...TPCA8048-H Output Capacitance (C2) 100 µF Rectifier Diode PDU540 Output Inductance (L1) 470 µH Switching Frequency ( fsw ) 93.3 kHz Np Ns/2 Ns/2Np...266V Output Current, Io 0.7519A Output Power, Po 200W Switching Frequency, fsw 100kHz Efficiency, η 97% Regulation, α 2% Operating Flux Density

  7. Background Acoustics Levels in the 9x15 Wind Tunnel and Linear Array Testing

    NASA Technical Reports Server (NTRS)

    Stephens, David

    2011-01-01

    The background noise level in the 9x15 foot wind tunnel at NASA Glenn has been documented, and the results compare favorably with historical measurements. A study of recessed microphone mounting techniques was also conducted, and a recessed cavity with a micronic wire mesh screen reduces hydrodynamic noise by around 10 dB. A three-microphone signal processing technique can provide additional benefit, rejecting up to 15 dB of noise contamination at some frequencies. The screen and cavity system offers considerable benefit to test efficiency, although there are additional calibration requirements.

  8. 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

  9. 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

  10. The advantages and disadvantages of centralized control of air power at operational level

    NASA Astrophysics Data System (ADS)

    Arisoy, Uǧur

    2014-05-01

    People do not want to see and hear a war. In today's world, if war is inevitable, the use of air power is seen as the preferable means of conducting operations instead of financially burdensome land battles which are more likely to cause heavy loss of life. The use of Air Power has gained importance in NATO operations in the Post-Cold War era. For example, air power has undertaken a decisive role from the beginning to the end of the operation in Libya. From this point of view, the most important issue to consider is how to direct air power more effectively at operational level. NATO's Core JFAC (Joint Force Air Command) was established in 2012 to control joint air power at operational level from a single center. US had experienced JFAC aproach in the Operation Desert Storm in 1991. UK, France, Germany, Italy and Spain are also directing their air power from their JFAC structures. Joint air power can be directed from a single center at operational level by means of JFAC. JFAC aproach provides complex planning progress of Air Power to be controled faster in a single center. An Air Power with a large number of aircrafts, long range missiles of cutting-edge technology may have difficulties in achieving results unless directed effectively. In this article, directing air power more effectively at operational level has been studied in the framework of directing air power from a single center carried out by SWOT analysis technique. "Directing Air Power at operational level from a single center similar to JFAC-like structure" is compared with "Directing Air Power at operational level from two centers similar to AC (Air Command) + CAOC (Combined Air Operations Center) structure" As a result of this study, it is assessed that directing air power at operational level from a single center would bring effectiveness to the air campaign. The study examines directing air power at operational level. Developments at political, strategic and tactical levels have been ignored.

  11. Analysis of power gating in different hierarchical levels of 2MB cache, considering variation

    NASA Astrophysics Data System (ADS)

    Jafari, Mohsen; Imani, Mohsen; Fathipour, Morteza

    2015-09-01

    This article reintroduces power gating technique in different hierarchical levels of static random-access memory (SRAM) design including cell, row, bank and entire cache memory in 16 nm Fin field effect transistor. Different structures of SRAM cells such as 6T, 8T, 9T and 10T are used in design of 2MB cache memory. The power reduction of the entire cache memory employing cell-level optimisation is 99.7% with the expense of area and other stability overheads. The power saving of the cell-level optimisation is 3× (1.2×) higher than power gating in cache (bank) level due to its superior selectivity. The access delay times are allowed to increase by 4% in the same energy delay product to achieve the best power reduction for each supply voltages and optimisation levels. The results show the row-level power gating is the best for optimising the power of the entire cache with lowest drawbacks. Comparisons of cells show that the cells whose bodies have higher power consumption are the best candidates for power gating technique in row-level optimisation. The technique has the lowest percentage of saving in minimum energy point (MEP) of the design. The power gating also improves the variation of power in all structures by at least 70%.

  12. 49 CFR 393.94 - Interior noise levels in power units.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 5 2012-10-01 2012-10-01 false Interior noise levels in power units. 393.94... noise levels in power units. (a) Applicability of this section. The interior noise level requirements..., if the reading has not been influenced by extraneous noise sources such as motor vehicles...

  13. 49 CFR 393.94 - Interior noise levels in power units.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 5 2014-10-01 2014-10-01 false Interior noise levels in power units. 393.94... noise levels in power units. (a) Applicability of this section. The interior noise level requirements..., if the reading has not been influenced by extraneous noise sources such as motor vehicles...

  14. Photovoltaic Shading Testbed for Module-Level Power Electronics

    SciTech Connect

    Deline, C.; Meydbray, J.; Donovan, M.; Forrest, J.

    2012-05-01

    This document describes a repeatable test procedure that attempts to simulate shading situations, as would be experienced by typical residential rooftop photovoltaic (PV) systems. This type of shading test is particularly useful to evaluate the impact of different power conversion setups, including microinverters, DC power optimizers and string inverters, on overall system performance. The performance results are weighted based on annual estimates of shade to predict annual performance improvement. A trial run of the test procedure was conducted with a side by side comparison of a string inverter with a microinverter, both operating on identical 8kW solar arrays. Considering three different shade weighting conditions, the microinverter was found to increase production by 3.7% under light shading, 7.8% under moderate shading, and 12.3% under heavy shading, relative to the reference string inverter case. Detail is provided in this document to allow duplication of the test method at different test installations and for different power electronics devices.

  15. 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.

  16. Acoustic field modulation in regenerators

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

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

    SciTech Connect

    Lee, S; Richard Dimenna, R

    2007-09-27

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

  18. Investigation of correlation of LF power modulation of light in natural and artificial illumination situations and acoustic emission

    NASA Astrophysics Data System (ADS)

    Kleeberg, Florian P.; Gutzmann, Holger L.; Weyer, Cornelia; Weiß, Jürgen; Dörfler, Joachim; Hahlweg, Cornelius F.

    2014-09-01

    The present paper is a follow up of a paper presented in 2013 at the Novel Optical Systems conference in the session on Optics and Music. It is derived from an ongoing study on the human perception of combined optical and acoustical periodical stimuli. Originating from problems concerning artificial illumination and certain machinery with coherent optical and acoustical emissions there are effects to be observed which are interesting in the context of occupational medicine. It seems, that acoustic stimuli in the frequency range of the flicker fusion and below might lead to unexpected perceptible effects beyond those of the single stimuli. The effect of infrasound stimuli as a whole body perception seems to be boosted. Because of the difficulties in evaluation of physical and psychological effects of such coherent stimuli in a first step we question if such coherence is perceivable at all. Further, the problem of modulation of optical signals by acoustical signal is concerned. A catalogue of scenarios and 'effects to look for' including measurement concepts is presented and discussed.

  19. Variation of solar acoustic emission and its relation to phase of the solar cycle

    NASA Astrophysics Data System (ADS)

    Chen, Ruizhu; Zhao, Junwei

    2016-05-01

    Solar acoustic emission is closely related to solar convection and photospheric magnetic field. Variation of acoustic emission and its relation to the phase of solar cycles are important to understand dynamics of solar cycles and excitation of acoustic waves. In this work we use 6 years of SDO/HMI Dopplergram data to study acoustic emissions of the whole sun and of the quiet-sun regions, respectively, in multiple acoustic frequency bands. We show the variation of acoustic emission from May 2010 to April 2016, covering half of the solar cycle 24, and analyze its correlation with the solar activity level indexed by daily sunspot number and total magnetic flux. Results show that the correlation between the whole-Sun acoustic emission and the solar activity level is strongly negative for low frequencies between 2.5 and 4.5 mHz, but strongly positive for high frequencies between 4.5 and 6.0 mHz. For high frequencies, the acoustic emission excess in sunspot halos overwhelms the emission deficiency in sunspot umbrae and penumbrae. The correlation between the acoustic emission in quiet regions and the solar activity level is negative for 2.5-4.0 mHz and positive for 4.0-5.5 mHz. This shows that the solar background acoustic power, with active regions excluded, also varies during a solar cycle, implying the excitation frequencies or depths are highly related to the solar magnetic field.

  20. Vocal communication in a complex multi-level society: constrained acoustic structure and flexible call usage in Guinea baboons

    PubMed Central

    2013-01-01

    Background To understand the evolution of acoustic communication in animals, it is important to distinguish between the structure and the usage of vocal signals, since both aspects are subject to different constraints. In terrestrial mammals, the structure of calls is largely innate, while individuals have a greater ability to actively initiate or withhold calls. In closely related taxa, one would therefore predict a higher flexibility in call usage compared to call structure. In the present study, we investigated the vocal repertoire of free living Guinea baboons (Papio papio) and examined the structure and usage of the animals’ vocal signals. Guinea baboons live in a complex multi-level social organization and exhibit a largely tolerant and affiliative social style, contrary to most other baboon taxa. To classify the vocal repertoire of male and female Guinea baboons, cluster analyses were used and focal observations were conducted to assess the usage of vocal signals in the particular contexts. Results In general, the vocal repertoire of Guinea baboons largely corresponded to the vocal repertoire other baboon taxa. The usage of calls, however, differed considerably from other baboon taxa and corresponded with the specific characteristics of the Guinea baboons’ social behaviour. While Guinea baboons showed a diminished usage of contest and display vocalizations (a common pattern observed in chacma baboons), they frequently used vocal signals during affiliative and greeting interactions. Conclusions Our study shows that the call structure of primates is largely unaffected by the species’ social system (including grouping patterns and social interactions), while the usage of calls can be more flexibly adjusted, reflecting the quality of social interactions of the individuals. Our results support the view that the primary function of social signals is to regulate social interactions, and therefore the degree of competition and cooperation may be more important

  1. Power levels in office equipment: Measurements of new monitors and personal computers

    SciTech Connect

    Roberson, Judy A.; Brown, Richard E.; Nordman, Bruce; Webber, Carrie A.; Homan, Gregory H.; Mahajan, Akshay; McWhinney, Marla; Koomey, Jonathan G.

    2002-05-14

    Electronic office equipment has proliferated rapidly over the last twenty years and is projected to continue growing in the future. Efforts to reduce the growth in office equipment energy use have focused on power management to reduce power consumption of electronic devices when not being used for their primary purpose. The EPA ENERGY STAR[registered trademark] program has been instrumental in gaining widespread support for power management in office equipment, and accurate information about the energy used by office equipment in all power levels is important to improving program design and evaluation. This paper presents the results of a field study conducted during 2001 to measure the power levels of new monitors and personal computers. We measured off, on, and low-power levels in about 60 units manufactured since July 2000. The paper summarizes power data collected, explores differences within the sample (e.g., between CRT and LCD monitors), and discusses some issues that arise in m etering office equipment. We also present conclusions to help improve the success of future power management programs.Our findings include a trend among monitor manufacturers to provide a single very low low-power level, and the need to standardize methods for measuring monitor on power, to more accurately estimate the annual energy consumption of office equipment, as well as actual and potential energy savings from power management.

  2. Sub-Poissonian phonon statistics in an acoustical resonator coupled to a pumped two-level emitter

    NASA Astrophysics Data System (ADS)

    Ceban, V.; Macovei, M. A.

    2015-11-01

    The concept of an acoustical analog of the optical laser has been developed recently in both theoretical and experimental works. We here discuss a model of a coherent phonon generator with a direct signature of the quantum properties of sound vibrations. The considered setup is made of a laser-driven quantum dot embedded in an acoustical nanocavity. The system dynamics is solved for a single phonon mode in the steady-state and in the strong quantum dot—phonon coupling regime beyond the secular approximation. We demonstrate that the phonon statistics exhibits quantum features, i.e., is sub-Poissonian.

  3. Sub-Poissonian phonon statistics in an acoustical resonator coupled to a pumped two-level emitter

    SciTech Connect

    Ceban, V. Macovei, M. A.

    2015-11-15

    The concept of an acoustical analog of the optical laser has been developed recently in both theoretical and experimental works. We here discuss a model of a coherent phonon generator with a direct signature of the quantum properties of sound vibrations. The considered setup is made of a laser-driven quantum dot embedded in an acoustical nanocavity. The system dynamics is solved for a single phonon mode in the steady-state and in the strong quantum dot—phonon coupling regime beyond the secular approximation. We demonstrate that the phonon statistics exhibits quantum features, i.e., is sub-Poissonian.

  4. Effect of Acoustic Power on In Vivo Molecular Imaging with Targeted Microbubbles: Implications for Low-Mechanical Index Real-Time Imaging

    PubMed Central

    Kaufmann, Beat A.; Carr, Chad L.; Belcik, Todd; Xie, Aris; Kron, Benjamin; Yue, Qi; Lindner, Jonathan R.

    2009-01-01

    The aim of this study was to evaluate the influence of acoustic power on ultrasound molecular imaging data with targeted microbubbles. Imaging was performed with a contrast-specific multipulse method at a mechanical index (MI) of 0.18 and 0.97. In vitro imaging was used to measure concentration-intensity relationships and to assess whether damping from microbubble attachment to cultured endothelial cells affects signal enhancement. Power-related differences in signal enhancement were evaluated in vivo by P-selectin-targeted and control microbubble imaging in a murine model of hindlimb ischemia-reperfusion injury. During in vitro experiments there was minimal acoustic damping from microbubble-cell attachment at either MI. Signal enhancement in the in vitro and in vivo experiments was 2-3-fold higher for high-MI compared with low-MI imaging which was due to greater pixel intensity, detection of a greater number of retained microbubbles, and increased point-spread function. Yet, there was a linear relationship between high- and low-MI data indicating that the relative degree of enhancement was similar. We conclude that during molecular imaging high-MI protocols produce more robust targeted signal enhancement than low-MI, although differences in relative enhancement caused by condition or agent are similar. PMID:19910159

  5. Acoustic well cleaner

    DOEpatents

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

    1997-01-21

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

  6. Analyzing panel acoustic contributions toward the sound field inside the passenger compartment of a full-size automobile.

    PubMed

    Wu, Sean F; Moondra, Manmohan; Beniwal, Ravi

    2015-04-01

    The Helmholtz equation least squares (HELS)-based nearfield acoustical holography (NAH) is utilized to analyze panel acoustic contributions toward the acoustic field inside the interior region of an automobile. Specifically, the acoustic power flows from individual panels are reconstructed, and relative contributions to sound pressure level and spectrum at any point of interest are calculated. Results demonstrate that by correlating the acoustic power flows from individual panels to the field acoustic pressure, one can correctly locate the panel allowing the most acoustic energy transmission into the vehicle interior. The panel on which the surface acoustic pressure amplitude is the highest should not be used as indicative of the panel responsible for the sound field in the vehicle passenger compartment. Another significant advantage of this HELS-based NAH is that measurements of the input data only need to be taken once by using a conformal array of microphones in the near field, and ranking of panel acoustic contributions to any field point can be readily performed. The transfer functions between individual panels of any vibrating structure to the acoustic pressure anywhere in space are calculated not measured, thus significantly reducing the time and effort involved in panel acoustic contributions analyses.

  7. Using Nano-mechanics and Surface Acoustic Wave (SAW) for Disease Monitoring and Diagnostics at a Cellular Level in Red Blood Cells

    NASA Astrophysics Data System (ADS)

    Sivanantha, Ninnuja; Ma, Charles; Collins, David J.; Sesen, Muhsincan; Brenker, Jason; Coppel, Ross L.; Neild, Adrian; Alan, Tuncay

    A popular approach to monitoring diseases and their diagnosis is through biological, pathological or immunological characterization. However, at a cellular level progression of certain diseases manifests itself through mechanical effects as well. Here, we present a method which exploits localised flow; surface acoustic wave (SAW) induced acoustic streaming in a 9 μL droplet to characterize the adhesive properties of red blood cells (healthy, gluteraldehyde treated and malaria infected) in approximately 50 seconds. Our results show a 79% difference in cell mobilization between healthy malaria infected RBCs (and a 39% difference between healthy and treated ones), indicating that the method can serve as a platform for rapid clinical diagnosis; where separation of two or more different cell populations in a mixed solution is desirable. It can also act as a key biomarker for monitoring some diseases offering quantitative measures of disease progression and response to therapy.

  8. Measurement and Characterization of Space Shuttle Solid Rocket Motor Plume Acoustics

    NASA Technical Reports Server (NTRS)

    Kenny, Robert Jeremy

    2009-01-01

    NASA's current models to predict lift-off acoustics for launch vehicles are currently being updated using several numerical and empirical inputs. One empirical input comes from free-field acoustic data measured at three Space Shuttle Reusable Solid Rocket Motor (RSRM) static firings. The measurements were collected by a joint collaboration between NASA - Marshall Space Flight Center, Wyle Labs, and ATK Launch Systems. For the first time NASA measured large-thrust solid rocket motor plume acoustics for evaluation of both noise sources and acoustic radiation properties. Over sixty acoustic free-field measurements were taken over the three static firings to support evaluation of acoustic radiation near the rocket plume, far-field acoustic radiation patterns, plume acoustic power efficiencies, and apparent noise source locations within the plume. At approximately 67 m off nozzle centerline and 70 m downstream of the nozzle exit plan, the measured overall sound pressure level of the RSRM was 155 dB. Peak overall levels in the far field were over 140 dB at 300 m and 50-deg off of the RSRM thrust centerline. The successful collaboration has yielded valuable data that are being implemented into NASA's lift-off acoustic models, which will then be used to update predictions for Ares I and Ares V liftoff acoustic environments.

  9. Validation of the Predicted Circumferential and Radial Mode Sound Power Levels in the Inlet and Exhaust Ducts of a Fan Ingesting Distorted Inflow

    NASA Technical Reports Server (NTRS)

    Koch, L. Danielle

    2012-01-01

    Fan inflow distortion tone noise has been studied computationally and experimentally. Data from two experiments in the NASA Glenn Advanced Noise Control Fan rig have been used to validate acoustic predictions. The inflow to the fan was distorted by cylindrical rods inserted radially into the inlet duct one rotor chord length upstream of the fan. The rods were arranged in both symmetric and asymmetric circumferential patterns. In-duct and farfield sound pressure level measurements were recorded. It was discovered that for positive circumferential modes, measured circumferential mode sound power levels in the exhaust duct were greater than those in the inlet duct and for negative circumferential modes, measured total circumferential mode sound power levels in the exhaust were less than those in the inlet. Predicted trends in overall sound power level were proven to be useful in identifying circumferentially asymmetric distortion patterns that reduce overall inlet distortion tone noise, as compared to symmetric arrangements of rods. Detailed comparisons between the measured and predicted radial mode sound power in the inlet and exhaust duct indicate limitations of the theory.

  10. 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.

  11. 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.

  12. Acoustic energy harvesting based on a planar acoustic metamaterial

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  13. Virtual reflections in electronic acoustic architecture

    NASA Astrophysics Data System (ADS)

    van Munster, Bjorn

    2005-09-01

    In the era of the ancient Greeks and Byzantines, the first attempts for increasing reverberation time are noted. In the 1950s, the Ambiophonic system accomplished this by means of an electronic device, for the first time. The early systems only increased the reverberation time by delaying the picked-up reverberation. With the introduction of multichannel feedback-based systems, the reverberation level also could be increased. Later, it was understood that it was important to also fill in the missing reflections, address reflection density, frequency dependence, etc. This resulted in the development of the SIAP concept. Current DSP technology led to the development of a processor whereby density, length, level, and the frequency content can be controlled for different areas in the same room or different rooms, leading to the concept of the acoustic server. electronic acoustic architecture has become the current state-of-the-art approach for solving acoustic deficiencies in, among others, rehearsal rooms, theaters, churches, and multipurpose venues. Incorporation of complementary passive acoustic solutions provides an optimum solution for all room problems. This paper discusses the utilization of virtual reflections in the new approach of electronic acoustic architecture for different environments. Measurements performed in the Sejong Performing Arts Centre, Seoul, South Korea, show the power of this approach.

  14. Some improvements on the auto-gated power for low-light level image intensifier

    NASA Astrophysics Data System (ADS)

    Yang, Ye; Yan, Bo; Zhi, Qiang; Yao, Ze; Li, Jun-guo; Fu, Ling-yun; Yuan, Yuan; Deng, Guang-xu

    2014-09-01

    The basic principle and formation of the auto-gated power using hybrid automatic brightness control scheme were described in detail. The auto-gated power supply in the application process because the device precision and the low-light level image intensifier between individual differences, fall may cause some products in some cases the SNR and resolution, and decrease the consistency of the product. This paper puts forward the corresponding solutions to these problems. And through experiments on the improved auto gated power supply with automatic gated power has not been improved compared. Applications of the auto-gated power in military, police and civil area were forecasted.

  15. Scaling and dimensional analysis of acoustic streaming jets

    NASA Astrophysics Data System (ADS)

    Moudjed, B.; Botton, V.; Henry, D.; Ben Hadid, H.; Garandet, J.-P.

    2014-09-01

    This paper focuses on acoustic streaming free jets. This is to say that progressive acoustic waves are used to generate a steady flow far from any wall. The derivation of the governing equations under the form of a nonlinear hydrodynamics problem coupled with an acoustic propagation problem is made on the basis of a time scale discrimination approach. This approach is preferred to the usually invoked amplitude perturbations expansion since it is consistent with experimental observations of acoustic streaming flows featuring hydrodynamic nonlinearities and turbulence. Experimental results obtained with a plane transducer in water are also presented together with a review of the former experimental investigations using similar configurations. A comparison of the shape of the acoustic field with the shape of the velocity field shows that diffraction is a key ingredient in the problem though it is rarely accounted for in the literature. A scaling analysis is made and leads to two scaling laws for the typical velocity level in acoustic streaming free jets; these are both observed in our setup and in former studies by other teams. We also perform a dimensional analysis of this problem: a set of seven dimensionless groups is required to describe a typical acoustic experiment. We find that a full similarity is usually not possible between two acoustic streaming experiments featuring different fluids. We then choose to relax the similarity with respect to sound attenuation and to focus on the case of a scaled water experiment representing an acoustic streaming application in liquid metals, in particular, in liquid silicon and in liquid sodium. We show that small acoustic powers can yield relatively high Reynolds numbers and velocity levels; this could be a virtue for heat and mass transfer applications, but a drawback for ultrasonic velocimetry.

  16. Scaling and dimensional analysis of acoustic streaming jets

    SciTech Connect

    Moudjed, B.; Botton, V.; Henry, D.; Ben Hadid, H.

    2014-09-15

    This paper focuses on acoustic streaming free jets. This is to say that progressive acoustic waves are used to generate a steady flow far from any wall. The derivation of the governing equations under the form of a nonlinear hydrodynamics problem coupled with an acoustic propagation problem is made on the basis of a time scale discrimination approach. This approach is preferred to the usually invoked amplitude perturbations expansion since it is consistent with experimental observations of acoustic streaming flows featuring hydrodynamic nonlinearities and turbulence. Experimental results obtained with a plane transducer in water are also presented together with a review of the former experimental investigations using similar configurations. A comparison of the shape of the acoustic field with the shape of the velocity field shows that diffraction is a key ingredient in the problem though it is rarely accounted for in the literature. A scaling analysis is made and leads to two scaling laws for the typical velocity level in acoustic streaming free jets; these are both observed in our setup and in former studies by other teams. We also perform a dimensional analysis of this problem: a set of seven dimensionless groups is required to describe a typical acoustic experiment. We find that a full similarity is usually not possible between two acoustic streaming experiments featuring different fluids. We then choose to relax the similarity with respect to sound attenuation and to focus on the case of a scaled water experiment representing an acoustic streaming application in liquid metals, in particular, in liquid silicon and in liquid sodium. We show that small acoustic powers can yield relatively high Reynolds numbers and velocity levels; this could be a virtue for heat and mass transfer applications, but a drawback for ultrasonic velocimetry.

  17. 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.

  18. Effect of acoustic frequency and power density on the aqueous ultrasonic-assisted extraction of grape pomace (Vitis vinifera L.) - a response surface approach.

    PubMed

    González-Centeno, María Reyes; Knoerzer, Kai; Sabarez, Henry; Simal, Susana; Rosselló, Carmen; Femenia, Antoni

    2014-11-01

    Aqueous ultrasound-assisted extraction (UAE) of grape pomace was investigated by Response Surface Methodology (RSM) to evaluate the effect of acoustic frequency (40, 80, 120kHz), ultrasonic power density (50, 100, 150W/L) and extraction time (5, 15, 25min) on total phenolics, total flavonols and antioxidant capacity. All the process variables showed a significant effect on the aqueous UAE of grape pomace (p<0.05). The Box-Behnken Design (BBD) generated satisfactory mathematical models which accurately explain the behavior of the system; allowing to predict both the extraction yield of phenolic and flavonol compounds, and also the antioxidant capacity of the grape pomace extracts. The optimal UAE conditions for all response factors were a frequency of 40kHz, a power density of 150W/L and 25min of extraction time. Under these conditions, the aqueous UAE would achieve a maximum of 32.31mg GA/100g fw for total phenolics and 2.04mg quercetin/100g fw for total flavonols. Regarding the antioxidant capacity, the maximum predicted values were 53.47 and 43.66mg Trolox/100g fw for CUPRAC and FRAP assays, respectively. When comparing with organic UAE, in the present research, from 12% to 38% of total phenolic bibliographic values were obtained, but using only water as the extraction solvent, and applying lower temperatures and shorter extraction times. To the best of the authors' knowledge, no studies specifically addressing the optimization of both acoustic frequency and power density during aqueous-UAE of plant materials have been previously published.

  19. 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 ...

  20. Acoustic Seaglider

    DTIC Science & Technology

    2008-03-07

    a national naval responsibility. Acoustic sensors on mobile, autonomous platforms will enable basic research topics on temporal and spatial...problem and acoustic navigation and communications within the context of distributed autonomous persistent undersea surveillance sensor networks...Acoustic sensors on mobile, autonomous platforms will enable basic research topics on temporal and spatial coherence and the description of ambient

  1. 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.

  2. 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.

  3. The Impact of Covariates on Statistical Power in Cluster Randomized Designs: Which Level Matters More?

    PubMed

    Konstantopoulos, Spyros

    2012-06-18

    Field experiments with nested structures are becoming increasingly common, especially designs that assign randomly entire clusters such as schools to a treatment and a control group. In such large-scale cluster randomized studies the challenge is to obtain sufficient power of the test of the treatment effect. The objective is to maximize power without adding many clusters that make the study much more expensive. In this article I discuss how power estimates of tests of treatment effects in balanced cluster randomized designs are affected by covariates at different levels. I use third-grade data from Project STAR, a field experiment about class size, to demonstrate how covariates that explain a considerable proportion of variance in outcomes increase power significantly. When lower level covariates are group-mean centered and clustering effects are larger, top-level covariates increase power more than lower level covariates. In contrast, when clustering effects are smaller and lower level covariates are grand-mean centered or uncentered, lower level covariates increase power more than top-level covariates.

  4. North Dakota Industrial Arts Teachers Handbook. Energy/Power Curriculum Guide, Level I.

    ERIC Educational Resources Information Center

    Mugan, Don

    This handbook provides teachers with support material to more fully implement the North Dakota Energy and Power Curriculum Guide, Level I. It first presents the body of knowledge for Energy/Power Technology as taken from the curriculum guide. The guide is then addressed unit by unit, topic by topic. These seven units are covered: Energy/Power…

  5. Building America Case Study: Photovoltaic Systems with Module-Level Power Electronics

    SciTech Connect

    2015-09-01

    Direct current (DC) power optimizers and microinverters (together known as module-level power electronics, or MLPE) are one of the fastest growing market segments in the solar industry. According to GTM Research in The Global PV Inverter Landscape 2015, over 55% of all residential photovoltaic (PV) installations in the United States used some form of MLPE in 2014.

  6. Bidirectional Five-Level Power Processing Interface for Low Voltage Battery Energy Storage System

    NASA Astrophysics Data System (ADS)

    Huang, Jain-Yi; Jou, Hurng-Liahng; Wu, Kuen-Der; Lin, You-Si; Wu, Jinn-Chang

    A bidirectional five-level power processing interface for low voltage battery energy storage system (BESS) is developed in this paper. This BESS consists of a bidirectional five-level DC-AC converter, a bidirectional dual boost/buck DC-DC converter and a battery set. This five-level DC-AC converter includes a bidirectional full-bridge converter and a bidirectional dual buck DC-DC converter. The five-level power processing interface can charge power to the battery set form the utility or discharge the power from the battery set to the utility depending on the demanded operation of user. A hardware prototype is developed to verify the performance of this BESS. Experimental results show the performance of the developed BESS is as expected.

  7. Ultrasound acoustic wave energy transfer and harvesting

    NASA Astrophysics Data System (ADS)

    Shahab, Shima; Leadenham, Stephen; Guillot, François; Sabra, Karim; Erturk, Alper

    2014-04-01

    This paper investigates low-power electricity generation from ultrasound acoustic wave energy transfer combined with piezoelectric energy harvesting for wireless applications ranging from medical implants to naval sensor systems. The focus is placed on an underwater system that consists of a pulsating source for spherical wave generation and a harvester connected to an external resistive load for quantifying the electrical power output. An analytical electro-acoustic model is developed to relate the source strength to the electrical power output of the harvester located at a specific distance from the source. The model couples the energy harvester dynamics (piezoelectric device and electrical load) with the source strength through the acoustic-structure interaction at the harvester-fluid interface. Case studies are given for a detailed understanding of the coupled system dynamics under various conditions. Specifically the relationship between the electrical power output and system parameters, such as the distance of the harvester from the source, dimensions of the harvester, level of source strength, and electrical load resistance are explored. Sensitivity of the electrical power output to the excitation frequency in the neighborhood of the harvester's underwater resonance frequency is also reported.

  8. Advanced Distributed Measurements and Data Processing at the Vibro-Acoustic Test Facility, GRC Space Power Facility, Sandusky, Ohio - an Architecture and an Example

    NASA Technical Reports Server (NTRS)

    Hill, Gerald M.; Evans, Richard K.

    2009-01-01

    A large-scale, distributed, high-speed data acquisition system (HSDAS) is currently being installed at the Space Power Facility (SPF) at NASA Glenn Research Center s Plum Brook Station in Sandusky, OH. This installation is being done as part of a facility construction project to add Vibro-acoustic Test Capabilities (VTC) to the current thermal-vacuum testing capability of SPF in support of the Orion Project s requirement for Space Environments Testing (SET). The HSDAS architecture is a modular design, which utilizes fully-remotely managed components, enables the system to support multiple test locations with a wide-range of measurement types and a very large system channel count. The architecture of the system is presented along with details on system scalability and measurement verification. In addition, the ability of the system to automate many of its processes such as measurement verification and measurement system analysis is also discussed.

  9. System-level power estimation using SystemC and aspect-oriented programming

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Abbasi, Naeem; Tan, Qingping

    2010-09-01

    Rapid system modelling and early evaluation of design characterisation are central to design space exploration. SystemC is used widely for system-level modelling, but it lacks the semantics to capture power consumption. The article presents a novel high-level power estimation methodology based on SystemC and aspect-oriented programming (AOP). Using a composite pattern, our methodology is applicable to the power estimation of a complex system. The proposed strategies support macro-models with multiple features. The experimental results are illustrated with case studies.

  10. Power Spectrum Analysis and Missing Level Statistics of Microwave Graphs with Violated Time Reversal Invariance

    NASA Astrophysics Data System (ADS)

    Białous, Małgorzata; Yunko, Vitalii; Bauch, Szymon; Ławniczak, Michał; Dietz, Barbara; Sirko, Leszek

    2016-09-01

    We present experimental studies of the power spectrum and other fluctuation properties in the spectra of microwave networks simulating chaotic quantum graphs with violated time reversal invariance. On the basis of our data sets, we demonstrate that the power spectrum in combination with other long-range and also short-range spectral fluctuations provides a powerful tool for the identification of the symmetries and the determination of the fraction of missing levels. Such a procedure is indispensable for the evaluation of the fluctuation properties in the spectra of real physical systems like, e.g., nuclei or molecules, where one has to deal with the problem of missing levels.

  11. Power Spectrum Analysis and Missing Level Statistics of Microwave Graphs with Violated Time Reversal Invariance.

    PubMed

    Białous, Małgorzata; Yunko, Vitalii; Bauch, Szymon; Ławniczak, Michał; Dietz, Barbara; Sirko, Leszek

    2016-09-30

    We present experimental studies of the power spectrum and other fluctuation properties in the spectra of microwave networks simulating chaotic quantum graphs with violated time reversal invariance. On the basis of our data sets, we demonstrate that the power spectrum in combination with other long-range and also short-range spectral fluctuations provides a powerful tool for the identification of the symmetries and the determination of the fraction of missing levels. Such a procedure is indispensable for the evaluation of the fluctuation properties in the spectra of real physical systems like, e.g., nuclei or molecules, where one has to deal with the problem of missing levels.

  12. A point acoustic device based on aluminum nanowires

    NASA Astrophysics Data System (ADS)

    Xie, Qian-Yi; Ju, Zhen-Yi; Tian, He; Xue, Qing-Tang; Chen, Yuan-Quan; Tao, Lu-Qi; Mohammad, Mohammad Ali; Zhang, Xue-Yue; Yang, Yi; Ren, Tian-Ling

    2016-03-01

    A point Electrical Thermal Acoustic (ETA) device based on aluminum nanowire contacts is designed and fabricated. Interdigitated structural aluminum nanowires are released from the substrate by Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE). By releasing the interdigitated structure, the nanowires contact each other at approximately 1 mm above the wafer, forming a Point Contact Structure (PCS). It is found that the PCS acoustic device realizes high efficiency when a biased AC signal is applied. The PCS acoustic device reaches a sound pressure level as high as 67 dB at a distance of 1 cm with 74 mW AC input. The power spectrum is flat, ranging from 2 kHz to 20 kHz with a less than +/-3 dB fluctuation. The highest normalized Sound Pressure Level (SPL) of the point contact structure acoustic device is 18 dB higher than the suspended aluminum wire acoustic device. Comparisons between the PCS acoustic device and the Suspended Aluminum Nanowire (SAN) acoustic device illustrate that the PCS acoustic device has a flatter power spectrum within the 20 kHz range, and enhances the SPL at a lower frequency. Enhancing the response at lower frequencies is extremely useful, which may enable earphone and loudspeaker applications within the frequency range of the human ear with the help of pulse density modulation.A point Electrical Thermal Acoustic (ETA) device based on aluminum nanowire contacts is designed and fabricated. Interdigitated structural aluminum nanowires are released from the substrate by Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE). By releasing the interdigitated structure, the nanowires contact each other at approximately 1 mm above the wafer, forming a Point Contact Structure (PCS). It is found that the PCS acoustic device realizes high efficiency when a biased AC signal is applied. The PCS acoustic device reaches a sound pressure level as high as 67 dB at a distance of 1 cm with 74 mW AC input. The power spectrum is flat, ranging from 2 k

  13. Characterization of high intensity focused ultrasound transducers using acoustic streaming.

    PubMed

    Hariharan, Prasanna; Myers, Matthew R; Robinson, Ronald A; Maruvada, Subha H; Sliwa, Jack; Banerjee, Rupak K

    2008-03-01

    A new approach for characterizing high intensity focused ultrasound (HIFU) transducers is presented. The technique is based upon the acoustic streaming field generated by absorption of the HIFU beam in a liquid medium. The streaming field is quantified using digital particle image velocimetry, and a numerical algorithm is employed to compute the acoustic intensity field giving rise to the observed streaming field. The method as presented here is applicable to moderate intensity regimes, above the intensities which may be damaging to conventional hydrophones, but below the levels where nonlinear propagation effects are appreciable. Intensity fields and acoustic powers predicted using the streaming method were found to agree within 10% with measurements obtained using hydrophones and radiation force balances. Besides acoustic intensity fields, the streaming technique may be used to determine other important HIFU parameters, such as beam tilt angle or absorption of the propagation medium.

  14. Scalability of components for kW-level average power few-cycle lasers.

    PubMed

    Hädrich, Steffen; Rothhardt, Jan; Demmler, Stefan; Tschernajew, Maxim; Hoffmann, Armin; Krebs, Manuel; Liem, Andreas; de Vries, Oliver; Plötner, Marco; Fabian, Simone; Schreiber, Thomas; Limpert, Jens; Tünnermann, Andreas

    2016-03-01

    In this paper, the average power scalability of components that can be used for intense few-cycle lasers based on nonlinear compression of modern femtosecond solid-state lasers is investigated. The key components of such a setup, namely, the gas-filled waveguides, laser windows, chirped mirrors for pulse compression and low dispersion mirrors for beam collimation, focusing, and beam steering are tested under high-average-power operation using a kilowatt cw laser. We demonstrate the long-term stable transmission of kW-level average power through a hollow capillary and a Kagome-type photonic crystal fiber. In addition, we show that sapphire substrates significantly improve the average power capability of metal-coated mirrors. Ultimately, ultrabroadband dielectric mirrors show negligible heating up to 1 kW of average power. In summary, a technology for scaling of few-cycle lasers up to 1 kW of average power and beyond is presented.

  15. Experimental demonstration of acoustic wave induced magnetization switching in dipole coupled magnetostrictive nanomagnets for ultralow power computing

    NASA Astrophysics Data System (ADS)

    Sampath, Vimal; D'Souza, Noel; Atkinson, Gary M.; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

    2016-09-01

    Dipole-coupled cobalt nanomagnet pairs of elliptical shape (with their major axes parallel) are delineated on 128° Y-cut lithium niobate. Each pair is initially magnetized along the major axis with a magnetic field forming the (↑↑) state. When an acoustic wave (AW) is launched in the substrate from interdigitated electrodes, the softer nanomagnet in the pair flips to produce the (↑↓) state since the AW modulates the stress anisotropy. This executes the logical NOT operation because the output bit encoded in the magnetization state of the softer nanomagnet becomes the logic complement of the input bit encoded in the magnetization of the harder one. The AW acts as a clock to trigger the NOT operation and the energy dissipated is a few tens of aJ. Such AW clocking can be utilized to flip nanomagnets in a chain sequentially to steer logic bits unidirectionally along a nanomagnetic logic wire with miniscule energy dissipation.

  16. 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.

  17. User's manual for levelized power generation cost using an IBM PC

    SciTech Connect

    Fuller, L.C.

    1985-06-01

    Programs for the estimation of levelized electric power generation costs using the BASIC interpreter on an IBM PC are described. Procedures for light-water reactor plants and coal-fired plants include capital investment cost, operation and maintenance cost, fuel cycle cost, nuclear decommissioning cost, and levelized total generation cost.

  18. Multiple external hazards compound level 3 PSA methods research of nuclear power plant

    NASA Astrophysics Data System (ADS)

    Wang, Handing; Liang, Xiaoyu; Zhang, Xiaoming; Yang, Jianfeng; Liu, Weidong; Lei, Dina

    2017-01-01

    2011 Fukushima nuclear power plant severe accident was caused by both earthquake and tsunami, which results in large amount of radioactive nuclides release. That accident has caused the radioactive contamination on the surrounding environment. Although this accident probability is extremely small, once such an accident happens that is likely to release a lot of radioactive materials into the environment, and cause radiation contamination. Therefore, studying accidents consequences is important and essential to improve nuclear power plant design and management. Level 3 PSA methods of nuclear power plant can be used to analyze radiological consequences, and quantify risk to the public health effects around nuclear power plants. Based on multiple external hazards compound level 3 PSA methods studies of nuclear power plant, and the description of the multiple external hazards compound level 3 PSA technology roadmap and important technical elements, as well as taking a coastal nuclear power plant as the reference site, we analyzed the impact of off-site consequences of nuclear power plant severe accidents caused by multiple external hazards. At last we discussed the impact of off-site consequences probabilistic risk studies and its applications under multiple external hazards compound conditions, and explained feasibility and reasonableness of emergency plans implementation.

  19. A Brief Historical Survey of Rocket Testing Induced Acoustic Environments at NASA SSC

    NASA Technical Reports Server (NTRS)

    Allgood, Daniel C.

    2012-01-01

    A survey was conducted of all the various rocket test programs that have been performed since the establishment of NASA Stennis Space Center. The relevant information from each of these programs were compiled and used to quantify the theoretical noise source levels using the NASA approved methodology for computing "acoustic loads generated by a propulsion system" (NASA SP ]8072). This methodology, which is outlined in Reference 1, has been verified as a reliable means of determining the noise source characteristics of rocket engines. This information is being provided to establish reference environments for new government/business residents to ascertain whether or not their activities will generate acoustic environments that are more "encroaching" in the NASA Fee Area. In this report, the designation of sound power level refers to the acoustic power of the rocket engine at the engine itself. This is in contrast to the sound pressure level associated with the propagation of the acoustic energy in the surrounding air. The first part of the survey documents the "at source" sound power levels and their dominant frequency bands for the range of engines tested at Stennis. The second part of the survey discusses how the acoustic energy levels will propagate non ]uniformly from the test stands. To demonstrate this, representative acoustic sound pressure mappings in the NASA Stennis Fee Area were computed for typical engine tests on the B ]1 and E ]1 test stands.

  20. The neonatal acoustic reflex.

    PubMed

    Weatherby, L A; Bennett, M J

    1980-01-01

    Probe tones from 220 Hz to 2 000 Hz were used to measure the static and dynamic acoustic impedance of 44 neonates. Acoustic reflex thresholds to broad band noise were obtained from every neonate tested when employing the higher frequency probe tones. The reflex threshold levels measured are similar to those of adults. The static impedance values are discussed to give a possible explanation of why reflex thresholds cannot be detected using conventional 220 Hz impedance bridges.

  1. Scale Model Thruster Acoustic Measurement Results

    NASA Technical Reports Server (NTRS)

    Kenny, R. Jeremy; Vargas, Magda B.

    2013-01-01

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

  2. Acoustic emission spectra and sonochemical activity in a 36 kHz sonoreactor.

    PubMed

    Son, Younggyu; Lim, Myunghee; Khim, Jeehyeong; Ashokkumar, Muthupandian

    2012-01-01

    During ultrasound-induced cavitation in liquids, acoustic emissions at fundamental and harmonic frequencies can be detected. The effect of acoustic emissions at harmonic frequencies on the sonochemical and sonophysical activities has not been explored, especially in large-scale sonoreactors. In this study, the acoustic emissions in the range, 0-250 kHz in a 36 kHz sonoreactor with varying liquid heights were studied and compared with the sonochemical activities. The acoustic pressures at both fundamental and harmonics decreased drastically as the liquid height was increased due to the attenuation of sound energy. It was observed that the increase in input power resulted in only an increase in the acoustic emissions at derivative frequencies such as, harmonics and subharmonics. The sonochemical activity, evaluated in terms of sonochemiluminescence and H2O2 yield, was not significantly enhanced at higher input power levels. This suggests that at higher power levels, the "extra" acoustic energy is not effectively used to generate primary cavitation activity; rather it is converted to generate acoustic emissions at harmonic and subharmonic frequencies. This is an important observation for the design of energy efficiency large-scale sonochemical reactors.

  3. Analog design optimization methodology for ultralow-power circuits using intuitive inversion-level and saturation-level parameters

    NASA Astrophysics Data System (ADS)

    Eimori, Takahisa; Anami, Kenji; Yoshimatsu, Norifumi; Hasebe, Tetsuya; Murakami, Kazuaki

    2014-01-01

    A comprehensive design optimization methodology using intuitive nondimensional parameters of inversion-level and saturation-level is proposed, especially for ultralow-power, low-voltage, and high-performance analog circuits with mixed strong, moderate, and weak inversion metal-oxide-semiconductor transistor (MOST) operations. This methodology is based on the synthesized charge-based MOST model composed of Enz-Krummenacher-Vittoz (EKV) basic concepts and advanced-compact-model (ACM) physics-based equations. The key concept of this methodology is that all circuit and system characteristics are described as some multivariate functions of inversion-level parameters, where the inversion level is used as an independent variable representative of each MOST. The analog circuit design starts from the first step of inversion-level design using universal characteristics expressed by circuit currents and inversion-level parameters without process-dependent parameters, followed by the second step of foundry-process-dependent design and the last step of verification using saturation-level criteria. This methodology also paves the way to an intuitive and comprehensive design approach for many kinds of analog circuit specifications by optimization using inversion-level log-scale diagrams and saturation-level criteria. In this paper, we introduce an example of our design methodology for a two-stage Miller amplifier.

  4. 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.

  5. Hybrid PV/diesel solar power system design using multi-level factor analysis optimization

    NASA Astrophysics Data System (ADS)

    Drake, Joshua P.

    Solar power systems represent a large area of interest across a spectrum of organizations at a global level. It was determined that a clear understanding of current state of the art software and design methods, as well as optimization methods, could be used to improve the design methodology. Solar power design literature was researched for an in depth understanding of solar power system design methods and algorithms. Multiple software packages for the design and optimization of solar power systems were analyzed for a critical understanding of their design workflow. In addition, several methods of optimization were studied, including brute force, Pareto analysis, Monte Carlo, linear and nonlinear programming, and multi-way factor analysis. Factor analysis was selected as the most efficient optimization method for engineering design as it applied to solar power system design. The solar power design algorithms, software work flow analysis, and factor analysis optimization were combined to develop a solar power system design optimization software package called FireDrake. This software was used for the design of multiple solar power systems in conjunction with an energy audit case study performed in seven Tibetan refugee camps located in Mainpat, India. A report of solar system designs for the camps, as well as a proposed schedule for future installations was generated. It was determined that there were several improvements that could be made to the state of the art in modern solar power system design, though the complexity of current applications is significant.

  6. US power plant sites at risk of future sea-level rise

    NASA Astrophysics Data System (ADS)

    Bierkandt, R.; Auffhammer, M.; Levermann, A.

    2015-12-01

    Unmitigated greenhouse gas emissions may increase global mean sea-level by about 1 meter during this century. Such elevation of the mean sea-level enhances the risk of flooding of coastal areas. We compute the power capacity that is currently out-of-reach of a 100-year coastal flooding but will be exposed to such a flood by the end of the century for different US states, if no adaptation measures are taken. The additional exposed capacity varies strongly among states. For Delaware it is 80% of the mean generated power load. For New York this number is 63% and for Florida 43%. The capacity that needs additional protection compared to today increases by more than 250% for Texas, 90% for Florida and 70% for New York. Current development in power plant building points towards a reduced future exposure to sea-level rise: proposed and planned power plants are less exposed than those which are currently operating. However, power plants that have been retired or canceled were less exposed than those operating at present. If sea-level rise is properly accounted for in future planning, an adaptation to sea-level rise may be costly but possible.

  7. Method for leveling the power output of an electromechanical battery as a function of speed

    DOEpatents

    Post, R.F.

    1999-03-16

    The invention is a method of leveling the power output of an electromechanical battery during its discharge, while at the same time maximizing its power output into a given load. The method employs the concept of series resonance, employing a capacitor the parameters of which are chosen optimally to achieve the desired near-flatness of power output over any chosen charged-discharged speed ratio. Capacitors are inserted in series with each phase of the windings to introduce capacitative reactances that act to compensate the inductive reactance of these windings. This compensating effect both increases the power that can be drawn from the generator before inductive voltage drops in the windings become dominant and acts to flatten the power output over a chosen speed range. The values of the capacitors are chosen so as to optimally flatten the output of the generator over the chosen speed range. 3 figs.

  8. Method for leveling the power output of an electromechanical battery as a function of speed

    DOEpatents

    Post, Richard F.

    1999-01-01

    The invention is a method of leveling the power output of an electromechanical battery during its discharge, while at the same time maximizing its power output into a given load. The method employs the concept of series resonance, employing a capacitor the parameters of which are chosen optimally to achieve the desired near-flatness of power output over any chosen charged-discharged speed ratio. Capacitors are inserted in series with each phase of the windings to introduce capacitative reactances that act to compensate the inductive reactance of these windings. This compensating effect both increases the power that can be drawn from the generator before inductive voltage drops in the windings become dominant and acts to flatten the power output over a chosen speed range. The values of the capacitors are chosen so as to optimally flatten the output of the generator over the chosen speed range.

  9. Design and operation of 140 GHz gyrotron oscillators for power levels up to 1 MW CW

    SciTech Connect

    Jory, H.; Bier, R.; Craig, L.J.; Felch, K.; Ives, L.; Lopez, N.; Spang, S.

    1986-12-01

    Varian has designed and tested 140 GHz gyrotron oscillators that have generated output powers of 100 kW CW and 200 kW for 1 ms pulses. Upcoming tubes will be designed to operate at power levels of 200 kW CW and ultimately up to 1 MW CW. The important design considerations which are addressed in the higher power tubes include the design of the electron gun, interaction circuit, and output window. These issues will be discussed and the results of the earlier 140 GHz gyrotron work at Varian will be summarized.

  10. Education in acoustics in Argentina

    NASA Astrophysics Data System (ADS)

    Miyara, Federico

    2002-11-01

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

  11. System-level power optimization for real-time distributed embedded systems

    NASA Astrophysics Data System (ADS)

    Luo, Jiong

    Power optimization is one of the crucial design considerations for modern electronic systems. In this thesis, we present several system-level power optimization techniques for real-time distributed embedded systems, based on dynamic voltage scaling, dynamic power management, and management of peak power and variance of the power profile. Dynamic voltage scaling has been widely acknowledged as an important and powerful technique to trade off dynamic power consumption and delay. Efficient dynamic voltage scaling requires effective variable-voltage scheduling mechanisms that can adjust voltages and clock frequencies adaptively based on workloads and timing constraints. For this purpose, we propose static variable-voltage scheduling algorithms utilizing criticalpath driven timing analysis for the case when tasks are assumed to have uniform switching activities, as well as energy-gradient driven slack allocation for a more general scenario. The proposed techniques can achieve closeto-optimal power savings with very low computational complexity, without violating any real-time constraints. We also present algorithms for power-efficient joint scheduling of multi-rate periodic task graphs along with soft aperiodic tasks. The power issue is addressed through both dynamic voltage scaling and power management. Periodic task graphs are scheduled statically. Flexibility is introduced into the static schedule to allow the on-line scheduler to make local changes to PE schedules through resource reclaiming and slack stealing, without interfering with the validity of the global schedule. We provide a unified framework in which the response times of aperiodic tasks and power consumption are dynamically optimized simultaneously. Interconnection network fabrics point to a new generation of power-efficient and scalable interconnection architectures for distributed embedded systems. As the system bandwidth continues to increase, interconnection networks become power/energy limited as

  12. Acoustic characteristics of large-scale STOL models at forward speed

    NASA Technical Reports Server (NTRS)

    Falarski, M. D.; Aoyagi, K.; Koenig, D. G.

    1972-01-01

    Wind-tunnel investigations of the acoustic characteristics of the externally blown jet flap (EBF) and augmentor wing STOL concepts are discussed. The large-scale EBF model was equipped with a triple-slotted flap blown by four JT15D turbofan engines with circular, coannular exhaust nozzles. The large-scale augmentor wing model was equipped with an unlined augmentor blown by a slot primary nozzle. The effects of airspeed and angle of attack on the acoustics of the EBF were small. Flap deflection had a greater effect on the acoustics of the augmentor wing than did airspeed. The total sound power was also significantly higher for landing indicating that turning in the augmentor generated acoustic energy. Airspeed produced a small aft shift in acoustic directivity with no significant change in the peak perceived noise levels or sound power levels. Small-scale research of the acoustics for the augmentor wing has shown that by blowing an acoustically treated augmentor with a lobed primary nozzle, the 95-PNdb noise level goal can be achieved or surpassed.

  13. Results of acoustic testing of the JT8D-109 refan engines

    NASA Technical Reports Server (NTRS)

    Burdsall, E. A.; Brochu, F. P.; Scaramella, V. M.

    1975-01-01

    A JT8D engine was modified to reduce jet noise levels by 6-8 PNdB at takeoff power without increasing fan generated noise levels. Designated the JT8D-109, the modified engines featured a larger single stage fan, and acoustic treatment in the fan discharge ducts. Noise levels were measured on an outdoor test facility for eight engine/acoustic treatment configurations. Compared to the baseline JT8D, the fully treated JT8D-109 showed reductions of 6 PNdB at takeoff, and 11 PNdB at a typical approach power setting.

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

    NASA Astrophysics Data System (ADS)

    Miklós, A.

    2015-09-01

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

  15. 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.

  16. Energy Use and Power Levels in New Monitors and Personal Computers

    SciTech Connect

    Roberson, Judy A.; Homan, Gregory K.; Mahajan, Akshay; Nordman, Bruce; Webber, Carrie A.; Brown, Richard E.; McWhinney, Marla; Koomey, Jonathan G.

    2002-07-23

    Our research was conducted in support of the EPA ENERGY STAR Office Equipment program, whose goal is to reduce the amount of electricity consumed by office equipment in the U.S. The most energy-efficient models in each office equipment category are eligible for the ENERGY STAR label, which consumers can use to identify and select efficient products. As the efficiency of each category improves over time, the ENERGY STAR criteria need to be revised accordingly. The purpose of this study was to provide reliable data on the energy consumption of the newest personal computers and monitors that the EPA can use to evaluate revisions to current ENERGY STAR criteria as well as to improve the accuracy of ENERGY STAR program savings estimates. We report the results of measuring the power consumption and power management capabilities of a sample of new monitors and computers. These results will be used to improve estimates of program energy savings and carbon emission reductions, and to inform rev isions of the ENERGY STAR criteria for these products. Our sample consists of 35 monitors and 26 computers manufactured between July 2000 and October 2001; it includes cathode ray tube (CRT) and liquid crystal display (LCD) monitors, Macintosh and Intel-architecture computers, desktop and laptop computers, and integrated computer systems, in which power consumption of the computer and monitor cannot be measured separately. For each machine we measured power consumption when off, on, and in each low-power level. We identify trends in and opportunities to reduce power consumption in new personal computers and monitors. Our results include a trend among monitor manufacturers to provide a single very low low-power level, well below the current ENERGY STAR criteria for sleep power consumption. These very low sleep power results mean that energy consumed when monitors are off or in active use has become more important in terms of contribution to the overall unit energy consumption (UEC

  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. A system-level mathematical model for evaluation of power train performance of load-leveled electric-vehicles

    NASA Technical Reports Server (NTRS)

    Purohit, G. P.; Leising, C. J.

    1984-01-01

    The power train performance of load leveled electric vehicles can be compared with that of nonload leveled systems by use of a simple mathematical model. This method of measurement involves a number of parameters including the degree of load leveling and regeneration, the flywheel mechanical to electrical energy fraction, and efficiencies of the motor, generator, flywheel, and transmission. Basic efficiency terms are defined and representative comparisons of a variety of systems are presented. Results of the study indicate that mechanical transfer of energy into and out of the flywheel is more advantageous than electrical transfer. An optimum degree of load leveling may be achieved in terms of the driving cycle, battery characteristics, mode of mechanization, and the efficiency of the components. For state of the art mechanically coupled flyheel systems, load leveling losses can be held to a reasonable 10%; electrically coupled systems can have losses that are up to six times larger. Propulsion system efficiencies for mechanically coupled flywheel systems are predicted to be approximately the 60% achieved on conventional nonload leveled systems.

  19. 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.

  20. Non-invasive liquid level and density gauge for nuclear power reactor pressure vessels

    SciTech Connect

    Baratta, A.J.; Jester, W.A.; Kenney, E.S.; Mc Master, I.B.; Schultz, M.A.

    1987-01-27

    A method is described of non-invasively determining the liquid coolant level and density in a nuclear power reactor pressure vessel comprising the steps: positioning at least three neutron detector fission chambers externally of the reactor pressure vessel at multiple spaced positions along the side of the fuel core. One of the neutron detectors is positioned at the side near the bottom of the fuel core. The multiple spaced positions along the side remove any ambiguity as to whether the liquid level is decreasing or increasing: shielding the neutron detector fission chamber from thermal neutrons to avoid the noise associated therewith, and eliminating the effects of gamma radiation from the detected signals; monitoring the detected neutron level signals to determine to coolant liquid level and density in the nuclear power reactor pressure vessel.

  1. Recovery of burner acoustic source structure from far-field sound spectra

    NASA Technical Reports Server (NTRS)

    Mahan, J. R.; Jones, J. D.

    1984-01-01

    A method is presented that permits the thermal-acoustic efficiency spectrum in a long turbulent burner to be recovered from the corresponding far-field sound spectrum. An acoustic source/propagation model is used based on the perturbation solution of the equations describing the unsteady one-dimensional flow of an inviscid ideal gas with a distributed heat source. The technique is applied to a long cylindrical hydrogen-flame burner operating over power levels of 4.5-22.3 kW. The results show that the thermal-acoustic efficiency at a given frequency, defined as the fraction of the total burner power converted to acoustic energy at that frequency, is rather insensitive to burner power, having a maximum value on the order of 10 to the -4th at 150 Hz and rolling off steeply with increasing frequency. Evidence is presented that acoustic agitation of the flame at low frequencies enhances the mixing of the unburned fuel and air with the hot products of combustion. The paper establishes the potential of the technique as a useful tool for characterizing the acoustic source structure in any burner, such as a gas turbine combustor, for which a reasonable acoustic propagation model can be postulated.

  2. InGaAs communication photodiodes: from low to high power level designs

    NASA Astrophysics Data System (ADS)

    Achouche, M.

    2009-01-01

    While InGaAs absorption material has been used for various applications up to 1.6μm wavelength, specific designs for low level detection have become of main interest using high responsivity and low dark current detectors. By adding an avalanche multiplication layer to form an avalanche photodiode (APD) using the Separated Absorption and Multiplication (SAM) structure, one can take advantage of the very low noise properties of multiplication process in large bandgap Al(Ga)(In)As material to improve receiver sensitivity by >10dB. Under high power level injection, specific PIN structures have been developed to improve space charge effects as needed for power applications such as microwave analog photonic links. Specific designs to achieve simultaneously broad bandwidth, high responsivity, very high power saturation and high linearity will be discussed.

  3. High-intensity focused ultrasound sonothrombolysis: the use of perfluorocarbon droplets to achieve clot lysis at reduced acoustic power.

    PubMed

    Pajek, Daniel; Burgess, Alison; Huang, Yuexi; Hynynen, Kullervo

    2014-09-01

    The purpose of this study was to evaluate use of intravascular perfluorocarbon droplets to reduce the sonication power required to achieve clot lysis with high-intensity focused ultrasound. High-intensity focused ultrasound with droplets was initially applied to blood clots in an in vitro flow apparatus, and inertial cavitation thresholds were determined. An embolic model for ischemic stroke was used to illustrate the feasibility of this technique in vivo. Recanalization with intravascular droplets was achieved in vivo at 24 ± 5% of the sonication power without droplets. Recanalization occurred in 71% of rabbits that received 1-ms pulsed sonications during continuous intravascular droplet infusion (p = 0.041 vs controls). Preliminary experiments indicated that damage was confined to the ultrasonic focus, suggesting that tolerable treatments would be possible with a more tightly focused hemispheric array that allows the whole focus to be placed inside of the main arteries in the human brain.

  4. LPT. Low power test (TAN640) interior. Basement level. Camera facing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    LPT. Low power test (TAN-640) interior. Basement level. Camera facing north. Cable trays and conduit cross tunnel between critical experiment cell and critical experiment control room. Construction 93% complete. Photographer: Jack L. Anderson. Date: October 23, 1957. INEEL negative no. 57-5339 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  5. The Evolution of Power System Planning with High Levels of Variable Renewable Generation

    SciTech Connect

    Katz, Jessica; Milligan, Michael

    2016-09-01

    Greening the Grid provides technical assistance to energy system planners, regulators, and grid operators to overcome challenges associated with integrating variable renewable energy into the grid. This document, part of the Greening the Grid introduces the evolution of power system planning with high levels of variable renewable generation.

  6. Prospective Physics Teachers' Level of Understanding Energy, Power and Force Concepts

    ERIC Educational Resources Information Center

    Saglam-Arslan, Aysegul; Kurnaz, Mehmet Altan

    2009-01-01

    The aim of this study is to determine prospective physics teachers' level of understanding of the concepts of energy and the related concepts of force and power. The study was carried out with the participation of 56 physics education department students at a university in Karadeniz region. All participants had previously taken an introductory…

  7. The Testing Behind The Test Facility: The Acoustic Design of the NASA Glenn Research Center's World-Class Reverberant Acoustic Test Facility

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC?s Plum Brook Station in Sandusky, Ohio, USA. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA?s space exploration program. T he large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 ft3 in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world?s known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada?s acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama, USA. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic de-sign and subsequent on-going construction.

  8. The Testing Behind the Test Facility: the Acoustic Design of the NASA Glenn Research Center's World-Class Reverberant Acoustic Test Facility

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Mark E.; Hozman, Aron D.; McNelis, Anne M.

    2010-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC s Plum Brook Station in Sandusky, Ohio, U.S.A. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA s space exploration program. The large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 ft3 in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world s known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada s acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama, U.S.A. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic design and subsequent ongoing construction.

  9. The Testing Behind The Test Facility: The Acoustic Design of the NASA Glenn Research Center's World-Class Reverberant Acoustic Test Facility

    NASA Technical Reports Server (NTRS)

    Hozman, Aron D.; Hughes, William O.; McNelis, Mark E.; McNelis, Anne M.

    2011-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA's space exploration program. The large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 cu ft in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world's known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada's acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama, USA. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic design and subsequent on-going construction.

  10. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  12. Survey of ambient electromagnetic and radio-frequency interference levels in nuclear power plants

    SciTech Connect

    Kercel, S.W.; Moore, M.R.; Blakeman, E.D.; Ewing, P.D.; Wood, R.T.

    1996-11-01

    This document reports the results of a survey of ambient electromagnetic conditions in representative nuclear power plants. The U.S. Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research engaged the Oak Ridge National Laboratory (ORNL) to perform these measurements to characterize the electromagnetic interference (EMI) and radio-frequency interference (RFI) levels that can be expected in nuclear power plant environments. This survey is the first of its kind, being based on long-term unattended observations. The data presented in this report were measured at eight different nuclear units and required 14 months to collect. A representative sampling of power plant conditions (reactor type, operating mode, site location) monitored over extended observation periods (up to 5 weeks) were selected to more completely determine the characteristic electromagnetic environment for nuclear power plants. Radiated electric fields were measured over the frequency range of 5 MHz to 8 GHz. Radiated magnetic fields and conducted EMI events were measured over the frequency range of 305 Hz to 5 MHz. Highest strength observations of the electromagnetic ambient environment across all measurement conditions at each site provide frequency-dependent profiles for EMI/RFI levels in nuclear power plants.

  13. Extending the R Library PROPER to Enable Power Calculations for Isoform-Level Analysis with EBSeq

    PubMed Central

    Gaye, Amadou

    2017-01-01

    RNA-Sequencing (RNA-Seq) has become a routine technology for investigating gene expression differences in comparative transcriptomic studies. Differential expression (DE) analysis of the isoforms of genes is just emerging now that expression (read counts) can be estimated with higher accuracy at the isoform level. Estimating the statistical power that can be achieved with a specific number of repeats is a key step in RNA-Seq analysis. The R library proper was developed to provide realistic empirical power analysis. However, proper uses differential expression methods more suited for power calculation of gene-level expression data. We propose extensions to this tool that would allow for power analysis which takes into account the specificities of isoforms expression. This was achieved by enabling the use of EBSeq, a DE approach well-tailored for isoform-level expression, as an additional analysis method within PROPER. The new extensions and exemplar code for their usage are freely available online at: https://github.com/agaye/proper_extension PMID:28119735

  14. Extending the R Library PROPER to Enable Power Calculations for Isoform-Level Analysis with EBSeq.

    PubMed

    Gaye, Amadou

    2016-01-01

    RNA-Sequencing (RNA-Seq) has become a routine technology for investigating gene expression differences in comparative transcriptomic studies. Differential expression (DE) analysis of the isoforms of genes is just emerging now that expression (read counts) can be estimated with higher accuracy at the isoform level. Estimating the statistical power that can be achieved with a specific number of repeats is a key step in RNA-Seq analysis. The R library proper was developed to provide realistic empirical power analysis. However, proper uses differential expression methods more suited for power calculation of gene-level expression data. We propose extensions to this tool that would allow for power analysis which takes into account the specificities of isoforms expression. This was achieved by enabling the use of EBSeq, a DE approach well-tailored for isoform-level expression, as an additional analysis method within PROPER. The new extensions and exemplar code for their usage are freely available online at: https://github.com/agaye/proper_extension.

  15. Photovoltaic Shading Testbed for Module-Level Power Electronics: 2016 Performance Data Update

    SciTech Connect

    Deline, Chris; Meydbray, Jenya; Donovan, Matt

    2016-09-01

    The 2012 NREL report 'Photovoltaic Shading Testbed for Module-Level Power Electronics' provides a standard methodology for estimating the performance benefit of distributed power electronics under partial shading conditions. Since the release of the report, experiments have been conducted for a number of products and for different system configurations. Drawing from these experiences, updates to the test and analysis methods are recommended. Proposed changes in data processing have the benefit of reducing the sensitivity to measurement errors and weather variability, as well as bringing the updated performance score in line with measured and simulated values of the shade recovery benefit of distributed PV power electronics. Also, due to the emergence of new technologies including sub-module embedded power electronics, the shading method has been extended to include power electronics that operate at a finer granularity than the module level. An update to the method is proposed to account for these emerging technologies that respond to shading differently than module-level devices. The partial shading test remains a repeatable test procedure that attempts to simulate shading situations as would be experienced by typical residential or commercial rooftop photovoltaic (PV) systems. Performance data for multiple products tested using this method are discussed, based on equipment from Enphase, Solar Edge, Maxim Integrated and SMA. In general, the annual recovery of shading losses from the module-level electronics evaluated is 25-35%, with the major difference between different trials being related to the number of parallel strings in the test installation rather than differences between the equipment tested. Appendix D data has been added in this update.

  16. Sound power and pressure level measurements in the inlet and outlet of an HRSG duct

    NASA Astrophysics Data System (ADS)

    Jungbauer, D. E.; Unruh, J. F.; Rose, S.; Pantermuehl, P. J.

    1995-04-01

    The ever-increasing size of cogeneration facilities has mandated the need for noise abatement in the design stage. Many noise projection models are available to the industry for predicting noise levels in and adjacent to new installations. However, the models all require accurate source noise information if valid noise predictions are to be expected. As a consequence of designing one of the world's largest cogeneration installations involving eight Model W-701 turbine units and their Heat Recovery Steam Generators (HRSGs), it became apparent that the attention between the exhaust of the turbine and the outlet of the HRSGs was not well known. Not having this information posed potentially expensive noise abatement modifications during the design and construction phases. In order to verify the adequacy of scaling studies from a W-501 turbine and HRSG to the W-701 system, a comprehensive field test of an existing W-501 installation was conducted. This paper describes the design of an acoustic intensity and sound pressure probe to operate inside the high-temperature ductwork, the access engineering required, data acquisition, and final results concerning noise attenuation across the HRSG.

  17. Micro acoustic spectrum analyzer

    DOEpatents

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

    2004-11-23

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

  18. 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.

  19. Dynamic considerations for composite metal-rubber laminate acoustic power coupling bellows with application to thermoacoustic refrigeration

    NASA Astrophysics Data System (ADS)

    Smith, Robert William

    Many electrically driven thermoacoustic refrigerators have employed corrugated metal bellows to couple work from an electro-mechanical transducer to the working fluid typically. An alternative bellows structure to mediate this power transfer is proposed: a laminated hollow cylinder comprised of alternating layers of rubber and metal 'hoop-stack'. Fatigue and visoelastic power dissipation in the rubber are critical considerations; strain energy density plays a role in both. Optimal aspect ratios for a rectangle corss-section in the rubber, for given values of bellows axial strain and oscillatory pressure loads are discussed. Comparisons of tearing energies estimated from known load cases and those obtained by finite element analysis for candidate dimensions are presented. The metal layers of bellows are subject to an out-of-plane buckling instability for the case of external pressure loading; failure of this type was experimentally observed. The proposed structure also exhibits column instability when subject to internal pressure, as do metal bellows. For hoop-stack bellows, shear deflection cannot be ignored and this leads to column instability for both internal and external pressures, the latter being analogous to the case of tension buckling of a beam. During prototype bellows testing, transverse modes of vibration are believed to have been excited parametrically as a consequence of the oscillatory pressures. Some operating frequencies of interest in this study lie above the cut-on frequency at which Timoshenko beam theory (TBT) predicts multiple phase speeds; it is shown that TBT fails to accurately predict both mode shapes and resonance frequencies in this regime. TBT is also shown to predict multiple phase speeds in the presence of axial tension, or external pressures, at magnitudes of interest in this study, over the entire frequency spectrum. For modes below cut-on absent a pressure differential (or equivalently, axial load) TBT predicts decreasing resonance

  20. Characterization of the differences in strength and power between different levels of competition in rugby union athletes.

    PubMed

    Argus, Christos K; Gill, Nicholas D; Keogh, Justin W L

    2012-10-01

    Levels of strength and power have been used to effectively discriminate between different levels of competition; however, there is limited literature in rugby union athletes. To assess the difference in strength and power between levels of competition, 112 rugby union players, including 43 professionals, 19 semiprofessionals, 32 academy level, and 18 high school level athletes, were assessed for bench press and box squat strength, and bench throw, and jump squat power. High school athletes were not assessed for jump squat power. Raw data along with data normalized to body mass with a derived power exponent were log transformed and analyzed. With the exception of box squat and bench press strength between professional and semiprofessional athletes, higher level athletes produced greater absolute and relative strength and power outputs than did lower level athletes (4-51%; small to very large effect sizes). Lower level athletes should strive to attain greater levels of strength and power in an attempt to reach or to be physically prepared for the next level of competition. Furthermore, the ability to produce high levels of power, rather than strength, may be a better determinate of playing ability between professional and semiprofessional athletes.

  1. A Transformer-less Partial Power Boost Converter for PV Applications Using a Three-Level Switching Cell

    SciTech Connect

    Agamy, Mohammed; Harfman-Todorovic, Maja; Elasser, Ahmed; Essakiappan, Somasundaram

    2013-03-01

    Photovoltaic architectures with distributed power electronics provide many advantages in terms of energy yield as well as system level optimization. As the power level of the solar farm increases it becomes more beneficial to increase the dc collection network voltage, which requires the use of power devices with higher voltage ratings, and thus making the design of efficient, low cost, distributed power converters more challenging. In this paper a simple partial power converter topology is proposed. The topology is implemented using a three-level switching cell, which allows the use of semiconductor devices with lower voltage rating; thus improving design and performance and reducing converter cost. This makes the converters suitable for use for medium to high power applications where dc-link voltages of 600V~1kV may be needed without the need for high voltage devices. Converter operation and experimental results are presented for two partial power circuit variants using three-level switching cells.

  2. Acoustic/Magnetic Stress Sensor

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.; Namkung, M.

    1986-01-01

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

  3. Spacecraft Internal Acoustic Environment Modeling

    NASA Technical Reports Server (NTRS)

    Chu, SShao-sheng R.; Allen, Christopher S.

    2009-01-01

    Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in vehicle development, first with estimates of noise sources, later with experimental data. In FY09, the physical mockup developed in FY08, with interior geometric shape similar to Orion CM (Crew Module) IML (Interior Mode Line), was used to validate SEA (Statistical Energy Analysis) acoustic model development with realistic ventilation fan sources. The sound power levels of these sources were unknown a priori, as opposed to previous studies that RSS (Reference Sound Source) with known sound power level was used. The modeling results were evaluated based on comparisons to measurements of sound pressure levels over a wide frequency range, including the frequency range where SEA gives good results. Sound intensity measurement was performed over a rectangular-shaped grid system enclosing the ventilation fan source. Sound intensities were measured at the top, front, back, right, and left surfaces of the and system. Sound intensity at the bottom surface was not measured, but sound blocking material was placed tinder the bottom surface to reflect most of the incident sound energy back to the remaining measured surfaces. Integrating measured sound intensities over measured surfaces renders estimated sound power of the source. The reverberation time T6o of the mockup interior had been modified to match reverberation levels of ISS US Lab interior for speech frequency bands, i.e., 0.5k, 1k, 2k, 4 kHz, by attaching appropriately sized Thinsulate sound absorption material to the interior wall of the mockup. Sound absorption of Thinsulate was modeled in three methods: Sabine equation with measured mockup interior reverberation time T60, layup model based on past impedance tube testing, and layup model plus air absorption correction. The evaluation/validation was

  4. POPCYCLE: a computer code for calculating nuclear and fossil plant levelized life-cycle power costs

    SciTech Connect

    Hardie, R.W.

    1982-02-01

    POPCYCLE, a computer code designed to calculate levelized life-cycle power costs for nuclear and fossil electrical generating plants is described. Included are (1) derivations of the equations and a discussion of the methodology used by POPCYCLE, (2) a description of the input required by the code, (3) a listing of the input for a sample case, and (4) the output for a sample case.

  5. A polymer optical fiber fuel level sensor: application to paramotoring and powered paragliding.

    PubMed

    Sánchez Montero, David; Contreras Lallana, Pedro; Vázquez, Carmen

    2012-01-01

    A low-cost intensity-based polymer optical fiber (POF) sensor for fuel level measurements in paramotoring and powered paragliding is presented, exploiting the advantages of the optical fiber sensing technology. Experimental results demonstrate that the best option can be performed by stripping the fiber at the desired discrete points to measure the fuel level as well as with a gauge-shape fiber bending. The prototype has a good linearity, better than 4% full scale (F.S.), and sensitivity around 0.5 V per bend are obtained. Hysteresis due to residual fluid at the sensing points is found to be less than 9% F.S.

  6. A Polymer Optical Fiber Fuel Level Sensor: Application to Paramotoring and Powered Paragliding

    PubMed Central

    Montero, David Sánchez; Lallana, Pedro Contreras; Vázquez, Carmen

    2012-01-01

    A low-cost intensity-based polymer optical fiber (POF) sensor for fuel level measurements in paramotoring and powered paragliding is presented, exploiting the advantages of the optical fiber sensing technology. Experimental results demonstrate that the best option can be performed by stripping the fiber at the desired discrete points to measure the fuel level as well as with a gauge-shape fiber bending. The prototype has a good linearity, better than 4% full scale (F.S.), and sensitivity around 0.5 V per bend are obtained. Hysteresis due to residual fluid at the sensing points is found to be less than 9% F.S. PMID:22778637

  7. Measuring acoustic habitats.

    PubMed

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

    2015-03-01

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

  8. Measuring acoustic habitats

    PubMed Central

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

    2015-01-01

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

  9. LLNL`s acoustic spectrometer

    SciTech Connect

    Baker, J.

    1997-03-17

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

  10. Acoustic absorption by sunspots

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  11. A procedure for combining acoustically induced and mechanically induced loads (first passage failure design criterion)

    NASA Technical Reports Server (NTRS)

    Crowe, D. R.; Henricks, W.

    1983-01-01

    The combined load statistics are developed by taking the acoustically induced load to be a random population, assumed to be stationary. Each element of this ensemble of acoustically induced loads is assumed to have the same power spectral density (PSD), obtained previously from a random response analysis employing the given acoustic field in the STS cargo bay as a stationary random excitation. The mechanically induced load is treated as either (1) a known deterministic transient, or (2) a nonstationary random variable of known first and second statistical moments which vary with time. A method is then shown for determining the probability that the combined load would, at any time, have a value equal to or less than a certain level. Having obtained a statistical representation of how the acoustic and mechanical loads are expected to combine, an analytical approximation for defining design levels for these loads is presented using the First Passage failure criterion.

  12. Acoustic emission intrusion detector

    DOEpatents

    Carver, Donald W.; Whittaker, Jerry W.

    1980-01-01

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

  13. Active-passive gradient shielding for MRI acoustic noise reduction.

    PubMed

    Edelstein, William A; Kidane, Tesfaye K; Taracila, Victor; Baig, Tanvir N; Eagan, Timothy P; Cheng, Yu-Chung N; Brown, Robert W; Mallick, John A

    2005-05-01

    An important source of MRI acoustic noise-magnet cryostat warm-bore vibrations caused by eddy-current-induced forces-can be mitigated by a passive metal shield mounted on the outside of a vibration-isolated, vacuum-enclosed shielded gradient set. Finite-element (FE) calculations for a z-gradient indicate that a 2-mm-thick Cu layer wrapped on the gradient assembly can decrease mechanical power deposition in the warm bore and reduce warm-bore acoustic noise production by about 25 dB. Eliminating the conducting warm bore and other magnet parts as significant acoustic noise sources could lead to the development of truly quiet, fully functioning MRI systems with noise levels below 70 dB.

  14. Holograms for acoustics

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  15. High temperature acoustic levitator

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B. (Inventor)

    1984-01-01

    A system is described for acoustically levitating an object within a portion of a chamber that is heated to a high temperature, while a driver at the opposite end of the chamber is maintained at a relatively low temperature. The cold end of the chamber is constructed so it can be telescoped to vary the length (L sub 1) of the cold end portion and therefore of the entire chamber, so that the chamber remains resonant to a normal mode frequency, and so that the pressure at the hot end of the chamber is maximized. The precise length of the chamber at any given time, is maintained at an optimum resonant length by a feedback loop. The feedback loop includes an acoustic pressure sensor at the hot end of the chamber, which delivers its output to a control circuit which controls a motor that varies the length (L) of the chamber to a level where the sensed acoustic pressure is a maximum.

  16. Clean Power Plan Proposed Rule: Description of 2012 Unit-Level Data Using the eGRID Methodology

    EPA Pesticide Factsheets

    Describes the 2012 unit-level data using the eGRID Methodology. The unit-level emissions and generation data derived using the eGRID methodology was relied upon for calculating state goals for the Clean Power Plan

  17. 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

  18. 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.

  19. Alterative LEU designs for the FRM-II with power levels of 20-22 MW.

    SciTech Connect

    Hanan, N. A.; Smith, R. S.; Matos, J. E.

    1999-09-27

    Alternative LEU Designs for the FRM-II have been developed by the RERTR Program at Argonne National Laboratory (ANL) at the request of an FRM-II Expert Group established by the German Federal Government in January 1999 to evaluate the options for using LEU fuel instead of HEU fuel in cores with power levels of 20 MW. The ANL designs would use the same building structure and maintain as many of the HEU design features as practical. The range of potential LEU fuels was expanded from previous studies to include already-tested silicide fuels with uranium densities up to 6.7 g/cm{sup 3} and the new U-Mo fuels that show excellent prospects for achieving uranium densities in the 8-9 g/cm{sup 3} range. For each of the LEU cores; the design parameters were chosen to match the 50 day cycle length of the HEU core and to maximize the thermal neutron flux in the Cold Neutron Source and beam tubes. The studies concluded that an LEU core with a diameter of about 29 cm instead of 24 cm in HEU design and operating at a power level of 20 MW would have thermal neutron fluxes that are 0.85 times that of the HEU design at the center of the Cold Neutron Source. With a potential future upgrade to a power of 22 MW, this ratio would increase to 0.93.

  20. Islanding the power grid on the transmission level: less connections for more security

    NASA Astrophysics Data System (ADS)

    Mureddu, Mario; Caldarelli, Guido; Damiano, Alfonso; Scala, Antonio; Meyer-Ortmanns, Hildegard

    2016-10-01

    Islanding is known as a management procedure of the power system that is implemented at the distribution level to preserve sensible loads from outages and to guarantee the continuity in electricity supply, when a high amount of distributed generation occurs. In this paper we study islanding on the level of the transmission grid and shall show that it is a suitable measure to enhance energy security and grid resilience. We consider the German and Italian transmission grids. We remove links either randomly to mimic random failure events, or according to a topological characteristic, their so-called betweenness centrality, to mimic an intentional attack and test whether the resulting fragments are self-sustainable. We test this option via the tool of optimized DC power flow equations. When transmission lines are removed according to their betweenness centrality, the resulting islands have a higher chance of being dynamically self-sustainable than for a random removal. Less connections may even increase the grid’s stability. These facts should be taken into account in the design of future power grids.

  1. Islanding the power grid on the transmission level: less connections for more security.

    PubMed

    Mureddu, Mario; Caldarelli, Guido; Damiano, Alfonso; Scala, Antonio; Meyer-Ortmanns, Hildegard

    2016-10-07

    Islanding is known as a management procedure of the power system that is implemented at the distribution level to preserve sensible loads from outages and to guarantee the continuity in electricity supply, when a high amount of distributed generation occurs. In this paper we study islanding on the level of the transmission grid and shall show that it is a suitable measure to enhance energy security and grid resilience. We consider the German and Italian transmission grids. We remove links either randomly to mimic random failure events, or according to a topological characteristic, their so-called betweenness centrality, to mimic an intentional attack and test whether the resulting fragments are self-sustainable. We test this option via the tool of optimized DC power flow equations. When transmission lines are removed according to their betweenness centrality, the resulting islands have a higher chance of being dynamically self-sustainable than for a random removal. Less connections may even increase the grid's stability. These facts should be taken into account in the design of future power grids.

  2. Islanding the power grid on the transmission level: less connections for more security

    PubMed Central

    Mureddu, Mario; Caldarelli, Guido; Damiano, Alfonso; Scala, Antonio; Meyer-Ortmanns, Hildegard

    2016-01-01

    Islanding is known as a management procedure of the power system that is implemented at the distribution level to preserve sensible loads from outages and to guarantee the continuity in electricity supply, when a high amount of distributed generation occurs. In this paper we study islanding on the level of the transmission grid and shall show that it is a suitable measure to enhance energy security and grid resilience. We consider the German and Italian transmission grids. We remove links either randomly to mimic random failure events, or according to a topological characteristic, their so-called betweenness centrality, to mimic an intentional attack and test whether the resulting fragments are self-sustainable. We test this option via the tool of optimized DC power flow equations. When transmission lines are removed according to their betweenness centrality, the resulting islands have a higher chance of being dynamically self-sustainable than for a random removal. Less connections may even increase the grid’s stability. These facts should be taken into account in the design of future power grids. PMID:27713509

  3. Quad Cities Unit 2 Main Steam Line Acoustic Source Identification and Load Reduction

    SciTech Connect

    DeBoo, Guy; Ramsden, Kevin; Gesior, Roman

    2006-07-01

    The Quad Cities Units 1 and 2 have a history of steam line vibration issues. The implementation of an Extended Power Up-rate resulted in significant increases in steam line vibration as well as acoustic loading of the steam dryers, which led to equipment failures and fatigue cracking of the dryers. This paper discusses the results of extensive data collection on the Quad Cities Unit 2 replacement dryer and the Main Steam Lines. This data was taken with the intent of identifying acoustic sources in the steam system. Review of the data confirmed that vortex shedding coupled column resonance in the relief and safety valve stub pipes were the principal sources of large magnitude acoustic loads in the main steam system. Modifications were developed in sub-scale testing to alter the acoustic properties of the valve standpipes and add acoustic damping to the system. The modifications developed and installed consisted of acoustic side branches that were attached to the Electromatic Relief Valve (ERV) and Main Steam Safety Valve (MSSV) attachment pipes. Subsequent post-modification testing was performed in plant to confirm the effectiveness of the modifications. The modifications have been demonstrated to reduce vibration loads at full Extended Power Up-rate (EPU) conditions to levels below those at Original Licensed Thermal Power (OLTP). (authors)

  4. Acoustic asymmetric transmission based on time-dependent dynamical scattering

    NASA Astrophysics Data System (ADS)

    Wang, Qing; Yang, Yang; Ni, Xu; Xu, Ye-Long; Sun, Xiao-Chen; Chen, Ze-Guo; Feng, Liang; Liu, Xiao-Ping; Lu, Ming-Hui; Chen, Yan-Feng

    2015-06-01

    An acoustic asymmetric transmission device exhibiting unidirectional transmission property for acoustic waves is extremely desirable in many practical scenarios. Such a unique property may be realized in various configurations utilizing acoustic Zeeman effects in moving media as well as frequency-conversion in passive nonlinear acoustic systems and in active acoustic systems. Here we demonstrate a new acoustic frequency conversion process in a time-varying system, consisting of a rotating blade and the surrounding air. The scattered acoustic waves from this time-varying system experience frequency shifts, which are linearly dependent on the blade’s rotating frequency. Such scattering mechanism can be well described theoretically by an acoustic linear time-varying perturbation theory. Combining such time-varying scattering effects with highly efficient acoustic filtering, we successfully develop a tunable acoustic unidirectional device with 20 dB power transmission contrast ratio between two counter propagation directions at audible frequencies.

  5. Acoustic asymmetric transmission based on time-dependent dynamical scattering

    PubMed Central

    Wang, Qing; Yang, Yang; Ni, Xu; Xu, Ye-Long; Sun, Xiao-Chen; Chen, Ze-Guo; Feng, Liang; Liu, Xiao-ping; Lu, Ming-Hui; Chen, Yan-Feng

    2015-01-01

    An acoustic asymmetric transmission device exhibiting unidirectional transmission property for acoustic waves is extremely desirable in many practical scenarios. Such a unique property may be realized in various configurations utilizing acoustic Zeeman effects in moving media as well as frequency-conversion in passive nonlinear acoustic systems and in active acoustic systems. Here we demonstrate a new acoustic frequency conversion process in a time-varying system, consisting of a rotating blade and the surrounding air. The scattered acoustic waves from this time-varying system experience frequency shifts, which are linearly dependent on the blade’s rotating frequency. Such scattering mechanism can be well described theoretically by an acoustic linear time-varying perturbation theory. Combining such time-varying scattering effects with highly efficient acoustic filtering, we successfully develop a tunable acoustic unidirectional device with 20 dB power transmission contrast ratio between two counter propagation directions at audible frequencies. PMID:26038886

  6. 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.

  7. Holocene lake level changes at a lowland lake in northeastern Germany inferred from acoustic sub-bottom profiling and a transect of sediment cores

    NASA Astrophysics Data System (ADS)

    Dietze, Elisabeth; Zawiska, Izabela; Słowiński, Michał; Brauer, Achim

    2015-04-01

    Holocene lake level changes were studied at Lake Fürstenseer See, a typical lake with complex basin morphology in northeastern German sandur area. An acoustic sub-bottom profile and a transect of four long sediment cores in the deepest lake sub-basin were analyzed. The cores were dated with AMS-14C and correlated with multiple proxies (sediment facies, μ-XRF, macrofossils, subfossil Cladocera, carbonate isotopes). At sites in 10 and 15 m water depth, shifts in the sand-mud boundary, i.e. sediment limit sensu Digerfeldt (1986), allowed quantitative estimates of the absolute amplitude of lake level changes. At sites in 20 and 23 m water depth, the negative correlation of Ca and Ti reflect lake level changes qualitatively. During high lake stands massive organic muds were deposited. Lower lake levels isolated the lake sub-basins which reduced the overall water circulation and lead to the deposition of Ti-poor carbonate muds. Furthermore, macrofossil and subfossil Cladocera analyses were used as proxies for the intense reworking at the slope and for the trophic state of the lake, respectively. Lake levels were up to 4 m higher, e.g. around 5000 cal. yrs BP and during the Medieval time period (see also Kaiser et al., 2014). During the early to mid-Holocene (between 9400 and 6400 cal. yrs BP), Lake Fürstenseer See fluctuated at an at least 3-m lower level. Further water level changes can be related to known climatic events and regional human impact. Digerfeldt, G., 1986. Studies on past lake-level fluctuations. In Berglund, B. (ed.), Handbook of Holocene Palaeoecology and Palaeohydrology: 127-144. John Wiley & Sons, New York. Kaiser, K., Küster, M., Fülling, A., Theuerkauf, M., Dietze, E., Graventein, H., Koch, P.J., Bens, O., Brauer, A., 2014. Littoral landforms and pedosedimentary sequences indicating late Holocene lake-level changes in northern central Europe ' A case study from northeastern Germany. Geomorphology 216, 58-78.

  8. The "Essential Levels of Care" in Italy: when being explicit serves the devolution of powers.

    PubMed

    Torbica, Aleksandra; Fattore, Giovanni

    2005-12-01

    The definition of an explicit health benefit package in Italy has gained importance because of devolution of powers from the national level to the regions. The set of services to be guaranteed by the public sector are defined at national level, while regions are accountable for their provision. This contribution discusses the entitlements and the decision criteria adopted by Italian policy-making bodies. Entitlements to services are clearly defined for few sectors (mainly outpatient specialist care); for hospital care the benefit catalogue is vague. The definition of the health benefit package in Italy is an essential element of the relationship between the central government and the regions. It is argued that adequate monitoring systems and accountability procedures are still needed to make the essential levels of care an effective pivotal element of the Italian National Health Service.

  9. Powered ankle-foot prosthesis to assist level-ground and stair-descent gaits.

    PubMed

    Au, Samuel; Berniker, Max; Herr, Hugh

    2008-05-01

    The human ankle varies impedance and delivers net positive work during the stance period of walking. In contrast, commercially available ankle-foot prostheses are passive during stance, causing many clinical problems for transtibial amputees, including non-symmetric gait patterns, higher gait metabolism, and poorer shock absorption. In this investigation, we develop and evaluate a myoelectric-driven, finite state controller for a powered ankle-foot prosthesis that modulates both impedance and power output during stance. The system employs both sensory inputs measured local to the external prosthesis, and myoelectric inputs measured from residual limb muscles. Using local prosthetic sensing, we first develop two finite state controllers to produce biomimetic movement patterns for level-ground and stair-descent gaits. We then employ myoelectric signals as control commands to manage the transition between these finite state controllers. To transition from level-ground to stairs, the amputee flexes the gastrocnemius muscle, triggering the prosthetic ankle to plantar flex at terminal swing, and initiating the stair-descent state machine algorithm. To transition back to level-ground walking, the amputee flexes the tibialis anterior muscle, triggering the ankle to remain dorsiflexed at terminal swing, and initiating the level-ground state machine algorithm. As a preliminary evaluation of clinical efficacy, we test the device on a transtibial amputee with both the proposed controller and a conventional passive-elastic control. We find that the amputee can robustly transition between the finite state controllers through direct muscle activation, allowing rapid transitioning from level-ground to stair walking patterns. Additionally, we find that the proposed finite state controllers result in a more biomimetic ankle response, producing net propulsive work during level-ground walking and greater shock absorption during stair descent. The results of this study highlight the

  10. Acoustic 3D imaging of dental structures

    SciTech Connect

    Lewis, D.K.; Hume, W.R.; Douglass, G.D.

    1997-02-01

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

  11. Cardiac autonomic control in high level Brazilian power and endurance track-and-field athletes.

    PubMed

    Abad, C C C; do Nascimento, A M; Gil, S; Kobal, R; Loturco, I; Nakamura, F Y; Mostarda, C T; Irigoyen, M C

    2014-08-01

    The autonomic nervous system (ANS) has an important role in physical performance. However, the cardiac ANS activity in high-level track and field athletes has been poorly explored. Thus, we tested the hypothesis that endurance and power athletes would present a markedly different cardiac autonomic control at rest. We analyzed the cardiac ANS by means of time and frequency domains heart rate variability (HRV) analyses and by symbolic analysis. Endurance athletes showed higher pulse interval than power athletes (1,265±126 vs. 1,031±98 ms respectively; p<0.05). No differences were found in time and frequency domains between the groups. However, the LF%, HF% and LF/HF ratio presented high effect sizes (1.46, 1.46 and 1.30, respectively). The symbolic analysis revealed that endurance athletes had higher 2V parasympathetic modulation (36±6.5) than power athletes (24±9.3; p<0.05). A reduced 0V sympathetic modulation was observed in endurance athletes (21±9.9) compared to power athletes (33±11; p<0.05 and ES=1.30). Our results suggest greater parasympathetic modulation and less sympathetic modulation in endurance athletes compared to power athletes. Additionally, the type of HRV analysis needs to be chosen with well-defined criteria and caution because their use in assessing cardiac autonomic modulation can interfere with the interpretation of results. In practical terms, symbolic analysis appears to better discriminate between cardiac autonomic activities of athletes with different training backgrounds than frequency domain analysis.

  12. Effects on electrical distribution networks of dispersed power generation at high levels of connection penetration

    SciTech Connect

    Longrigg, P

    1983-07-01

    The advent and deployment of significant levels of photovoltaic and wind energy generation in the spatially dispersed mode (i.e., residential and intermediate load centers) may have deleterious effects upon existing protective relay equipment and its time-current coordination on radial distribution circuits to which power conditioning equipment may be connected for power sell-back purposes. The problems that may arise involve harmonic injection from power conditioning inverters that can affect protective relays and cause excessive voltage and current from induced series and parallel resonances on feeders and connected passive equipment. Voltage regulation, var requirements, and consumer metering can also be affected by this type of dispersed generation. The creation of islands of supply is also possible, particularly on rural supply systems. This paper deals mainly with the effects of harmonics and short-circuit currents from wind energy conversion systems (WECS) and photovoltaic (PV) systems upon the operating characteristics of distribution networks and relays and other protective equipment designed to ensure the safety and supply integrity of electrical utility networks. Traditionally, electrical supply networks have been designed for one-way power flow-from generation to load, with a balance maintained between the two by means of automatic generation and load-frequency controls. Dispersed generation, from renewables like WECS or PV or from nonrenewable resources, can change traditional power flow. These changes must be dealt with effectively if renewable energy resources are to be integrated into the utility distribution system. This paper gives insight into these problems and proposes some solutions.

  13. Effect of focused ultrasound stimulation at different ultrasonic power levels on the local field potential power spectrum

    NASA Astrophysics Data System (ADS)

    Yuan, Yi; Lu, Cheng-Biao; Li, Xiao-Li

    2015-08-01

    Local field potential (LFP) signals of the rat hippocampus were recorded under noninvasive focused ultrasound stimulation (FUS) with different ultrasonic powers. The LFP mean absolute power was calculated with the Welch algorithm at the delta, theta, alpha, beta, and gamma frequency bands. The experimental results demonstrate that the LFP mean absolute power at different frequency bands increases as the ultrasound power increases. Project supported by the National Natural Science Foundation of China (Grant No. 61273063), China Postdoctoral Science Foundation (Grant No. 2013M540215), and the Natural Science Foundation of Hebei Province, China (Grant No. F2014203161).

  14. Turbofan Acoustic Propagation and Radiation

    NASA Technical Reports Server (NTRS)

    Eversman, Walter

    2000-01-01

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

  15. Immunoglobulin levels, opsonic activity and phagocytic power in Egyptian thalassemic children.

    PubMed

    Khalifa, A S; Fattah, S A; Maged, Z; Sabry, F; Mohamed, H A

    1983-01-01

    Serum IgG, IgM and IgA were determined in 25 patients with homozygous beta thalassemia and 7 with the trait. The levels were increased in homozygous patients and increased further after splenectomy. Serum opsonic activity against Salmonella typhi and staphylococci was impaired in homozygous patients. Splenectomy caused more impairment against salmonella only. Similarly, phagocytic power against both organisms was lower in beta thalassemia. Further decrease against salmonella occurred after splenectomy. Patients with thalassemia trait did not differ from normal controls.

  16. A two-level structure for advanced space power system automation

    NASA Astrophysics Data System (ADS)

    Loparo, Kenneth A.; Chankong, Vira

    1990-05-01

    The tasks to be carried out during the three-year project period are: (1) performing extensive simulation using existing mathematical models to build a specific knowledge base of the operating characteristics of space power systems; (2) carrying out the necessary basic research on hierarchical control structures, real-time quantitative algorithms, and decision-theoretic procedures; (3) developing a two-level automation scheme for fault detection and diagnosis, maintenance and restoration scheduling, and load management; and (4) testing and demonstration. The outlines of the proposed system structure that served as a master plan for this project, work accomplished, concluding remarks, and ideas for future work are also addressed.

  17. A two-level structure for advanced space power system automation

    NASA Technical Reports Server (NTRS)

    Loparo, Kenneth A.; Chankong, Vira

    1990-01-01

    The tasks to be carried out during the three-year project period are: (1) performing extensive simulation using existing mathematical models to build a specific knowledge base of the operating characteristics of space power systems; (2) carrying out the necessary basic research on hierarchical control structures, real-time quantitative algorithms, and decision-theoretic procedures; (3) developing a two-level automation scheme for fault detection and diagnosis, maintenance and restoration scheduling, and load management; and (4) testing and demonstration. The outlines of the proposed system structure that served as a master plan for this project, work accomplished, concluding remarks, and ideas for future work are also addressed.

  18. Smart energy management and low-power design of sensor and actuator nodes on algorithmic level for self-powered sensorial materials and robotics

    NASA Astrophysics Data System (ADS)

    Bosse, Stefan; Behrmann, Thomas

    2011-06-01

    We propose and demonstrate a design methodology for embedded systems satisfying low power requirements suitable for self-powered sensor and actuator nodes. This design methodology focuses on 1. smart energy management at runtime and 2. application-specific System-On- Chip (SoC) design at design time, contributing to low-power systems on both algorithmic and technology level. Smart energy management is performed spatially at runtime by a behaviour-based or state-action-driven selection from a set of different (implemented) algorithms classified by their demand of computation power, and temporally by varying data processing rates. It can be shown that power/energy consumption of an application-specific SoC design depends strongly on computation complexity. Signal and control processing is modelled on abstract level using signal flow diagrams. These signal flow graphs are mapped to Petri Nets to enable direct high-level synthesis of digital SoC circuits using a multi-process architecture with the Communicating-Sequential-Process model on execution level. Power analysis using simulation techniques on gatelevel provides input for the algorithmic selection during runtime of the system, leading to a closed-loop design flow. Additionally, the signal-flow approach enables power management by varying the signal flow and data processing rates depending on actual energy consumption, estimated energy deposit, and required Quality-of-Service.

  19. R&D 100 Winner 2010: Acoustic Wave Biosensors

    SciTech Connect

    Larson, Richard; Branch, Darren; Edwards, Thayne

    2016-06-07

    The acoustic wave biosensor is innovative device that is a handheld, battery-powered, portable detection system capable of multiplex identification of a wide range of medically relevant pathogens and their biomolecular signatures — viruses, bacteria, proteins, and DNA — at clinically relevant levels. This detection occurs within minutes — not hours — at the point of care, whether that care is in a physician's office, a hospital bed, or at the scene of a biodefense or biomedical emergency.

  20. Modeling Photovoltaic Module-Level Power Electronics in the System Advisor Model; NREL (National Renewable Energy Laboratory)

    SciTech Connect

    2015-07-01

    Module-level power electronics, such as DC power optimizers, microinverters, and those found in AC modules, are increasing in popularity in smaller-scale photovoltaic (PV) systems as their prices continue to decline. Therefore, it is important to provide PV modelers with guidelines about how to model these distributed power electronics appropriately in PV modeling software. This paper extends the work completed at NREL that provided recommendations to model the performance of distributed power electronics in NREL’s popular PVWatts calculator [1], to provide similar guidelines for modeling these technologies in NREL's more complex System Advisor Model (SAM). Module-level power electronics - such as DC power optimizers, microinverters, and those found in AC modules-- are increasing in popularity in smaller-scale photovoltaic (PV) systems as their prices continue to decline. Therefore, it is important to provide PV modelers with guidelines about how to model these distributed power electronics appropriately in PV modeling software.

  1. Power Technology (Energy/Power). Industrial Arts, Senior High--Level II. North Dakota Senior High Industrial Arts Curriculum Guides.

    ERIC Educational Resources Information Center

    Lawrence, Allen; And Others

    This course guide for a power technology course is one of four developed for the energy/power area in the North Dakota senior high industrial arts education program. (Eight other guides are available for two other areas of Industrial Arts--graphic communications and production.) Part 1 provides such introductory information as a definition and…

  2. Design Parameters of a Miniaturized Piezoelectric Underwater Acoustic Transmitter

    PubMed Central

    Li, Huidong; Deng, Zhiqun Daniel; Yuan, Yong; Carlson, Thomas J.

    2012-01-01

    PZT ceramics have been widely used in underwater acoustic transducers. However, literature available discussing the design parameters of a miniaturized PZT-based low-duty-cycle transmitter is very limited. This paper discusses some of the design parameters—the backing material, driving voltage, PZT material type, power consumption and the transducer length of a miniaturized acoustic fish tag using a PZT tube. Four different types of PZT were evaluated with respect to the source level, energy consumption and bandwidth of the transducer. The effect of the tube length on the source level is discussed. The results demonstrate that ultralow-density closed-cell foam is the best backing material for the PZT tube. The Navy Type VI PZTs provide the best source level with relatively low energy consumption and that a low transducer capacitance is preferred for high efficiency. A 35% reduction in the transducer length results in 2 dB decrease in source level. PMID:23012534

  3. Experimental study on an S-band near-field microwave magnetron power transmission system on hundred-watt level

    NASA Astrophysics Data System (ADS)

    Zhang, Biao; Jiang, Wan; Yang, Yang; Yu, Chengyang; Huang, Kama; Liu, Changjun

    2015-11-01

    A multi-magnetron microwave source, a metamaterial transmitting antenna, and a large power rectenna array are presented to build a near-field 2.45 GHz microwave power transmission system. The square 1 m2 rectenna array consists of sixteen rectennas with 2048 Schottky diodes for large power microwave rectifying. It receives microwave power and converts them into DC power. The design, structure, and measured performance of a unit rectenna as well as the entail rectenna array are presented in detail. The multi-magnetron microwave power source switches between half and full output power levels, i.e. the half-wave and full-wave modes. The transmission antenna is formed by a double-layer metallic hole array, which is applied to combine the output power of each magnetron. The rectenna array DC output power reaches 67.3 W on a 1.2 Ω DC load at a distance of 5.5 m from the transmission antenna. DC output power is affected by the distance, DC load, and the mode of microwave power source. It shows that conventional low power Schottky diodes can be applied to a microwave power transmission system with simple magnetrons to realise large power microwave rectifying.

  4. Correlation between solar acoustic emission and phase of the solar cycle

    NASA Astrophysics Data System (ADS)

    Chen, R.; Zhao, J.

    2015-12-01

    The solar acoustic emission is closely related to solar convection and magnetic field. Understanding the relation between the acoustic emission and the phase of a solar cycle is important to understand the dynamics of solar cycles and excitation of acoustic waves. In this work we use 4 years of SDO/HMI data from 05/2010 to 04/2014, covering the growing phase of the solar cycle 24, to study the acoustic emissions of the whole sun and of only the quiet sun regions respectively, at multiple frequency bands. We also analyze the correlations between the acoustic emissions and solar activity level indexed by daily sunspot number and magnetic flux. The results show that the correlation between the whole-sun acoustic emission and solar activity level is negative for low frequencies at 2.5-4.5 mHz, with a peak value around -0.9, and is positive for high frequencies at 4.5-6.0 mHz, with a peak value around 0.9. For high frequencies, the acoustic emission excess in sunspot halos overwhelms the emission deficiency in sunspot umbrae and penumbrae. The correlation between the quiet-sun acoustic emission and solar activity level is negative for 2.5-4.0 mHz and positive for 4.0-5.5 mHz, with peak values over ±0.8. This shows that the solar background acoustic power, with active regions excluded, is indeed varying during a solar cycle, implying the excitation frequencies or depths are highly related to the solar magnetic field.

  5. Allowable Residual Contamination Levels in soil for decommissioning the Shippingport Atomic Power Station site

    SciTech Connect

    Kennedy, W.E. Jr.; Napier, B.A.; Soldat, J.K.

    1983-09-01

    As part of decommissioning the Shippingport Atomic Power Station, a fundamental concern is the determination of Allowable Residual Contamination Levels (ARCL) for radionuclides in the soil at the site. The ARCL method described in this report is based on a scenario/exposure-pathway analysis and compliance with an annual dose limit for unrestricted use of the land after decommissioning. In addition to naturally occurring radionuclides and fallout from weapons testing, soil contamination could potentially come from five other sources. These include operation of the Shippingport Station as a pressurized water reactor, operations of the Shippingport Station as a light-water breeder, operation of the nearby Beaver Valley reactors, releases during decommissioning, and operation of other nearby industries, including the Bruce-Mansfield coal-fired power plants. ARCL values are presented for 29 individual radionculides and a worksheet is provided so that ARCL values can be determined for any mixture of the individual radionuclides for any annual dose limit selected. In addition, a worksheet is provided for calculating present time soil concentration value that will decay to the ARCL values after any selected period of time, such as would occur during a period of restricted access. The ARCL results are presented for both unconfined (surface) and confined (subsurface) soil contamination. The ARCL method and results described in this report provide a flexible means of determining unrestricted-use site release conditions after decommissioning the Shippingport Atomic Power Station.

  6. Nonlinear Acoustics

    DTIC Science & Technology

    1974-02-14

    Wester- velt. [60] Streaming. In 1831, Michael Faraday [61] noted that currents of air were set up in the neighborhood of vibrating plates-the first... ducei in the case of a paramettc amy (from Berktay an Leahy 141). C’ "". k•, SEC 10.1 NONLINEAR ACOUSTICS 345 The principal results of their analysis

  7. Acoustical evaluation of preschool classrooms

    NASA Astrophysics Data System (ADS)

    Yang, Wonyoung; Hodgson, Murray

    2003-10-01

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

  8. Noise levels of operational helicopters of the OH-6 type designed to meet the LOH mission. [acoustic properties for various helicopter configurations

    NASA Technical Reports Server (NTRS)

    Wagner, R. A.

    1973-01-01

    Formulas relating overall sound pressure level (OASPL) to parameters such as horsepower required, tip speed, and thrust for main and tail rotors are presented for standard and quieted helicopters. Formulas relating OASPL to engine parameters such as horsepower output and percent power turbine rpm are presented for unmuffled and muffled engines. The linear scale was used in preference to any of the weighted scales because it resulted in more consistent agreement with the test data when the SPL is expressed in the usual parameters of tip speed, thrust generated and power required. It is recognized that the linear scale does not adequately reflect hearing response, and hence is not a good absolute measure for detection by humans. However, linear OASPL is believed to be useful as a relative means of comparing noise level variations of individual components in similar helicopters with reasonably modest design changes.

  9. New power source from fractional quantum energy levels of atomic hydrogen that surpasses internal combustion

    NASA Astrophysics Data System (ADS)

    Mills, R. L.; Ray, P.; Dhandapani, B.; Nansteel, M.; Chen, X.; He, J.

    2002-12-01

    Extreme ultraviolet (EUV) spectroscopy was recorded on microwave discharges of helium with 2% hydrogen. Novel emission lines were observed with energies of q·13.6 eV where q=1,2,3,4,6,7,8,9, or 11 or these lines inelastically scattered by helium atoms wherein 21.2 eV was absorbed in the excitation of He (1s 2) to He (1s 12p 1). These lines were identified as hydrogen transitions to electronic energy levels below the 'ground' state corresponding to fractional quantum numbers. Significant line broadening corresponding to an average hydrogen atom temperature of 33-38 eV was observed for helium-hydrogen discharge plasmas; whereas pure hydrogen showed no excessive broadening corresponding to an average hydrogen atom temperature of ≈3 eV. Since a significant increase in H temperature was observed with helium-hydrogen discharge plasmas, and energetic hydrino lines were observed at short wavelengths in the corresponding microwave plasmas that required a very significant reaction rate due to low photon detection efficiency in this region, the power balance was measured on the helium-hydrogen microwave plasmas. With a microwave input power of 30 W, the thermal output power was measured to be at least 300 W corresponding to a reactor temperature rise from room temperature to 900 °C within 90 s, a power density of 30 MW/m 3, and an energy balance of about -4×10 5 kJ/mol H 2 compared to the enthalpy of combustion of hydrogen of -241.8 kJ/mol H 2.

  10. Model Predictive Wind Turbine Control with Move-Blocking Strategy for Load Alleviation and Power Leveling

    NASA Astrophysics Data System (ADS)

    Jassmann, U.; Dickler, S.; Zierath, J.; Hakenberg, M.; Abel, D.

    2016-09-01

    This contribution presents a Model Predictive Controller (MPC) with moveblocking strategy for combined power leveling and load alleviation in wind turbine operation with a focus on extreme loads. The controller is designed for a 3 MW wind turbine developed by W2E Wind to Energy GmbH and compared to a baseline controller, using a classic control scheme, which currently operates the wind turbine. All simulations are carried out with a detailed multibody simulation turbine model implemented in alaska/Wind. The performance of the two different controllers is compared using a 50-year Extreme Operation Gust event, since it is one of the main design drivers for the wind turbine considered in this work. The implemented MPC is able to level electrical output power and reduce mechanical loads at the same time. Without de-rating the achieved control results, a move-blocking strategy is utilized and allowed to reduce the computational burden of the MPC by more than 50% compared to a baseline MPC implementation. This even allows to run the MPC on a state of the art Programmable Logic Controller.

  11. Default operational intervention levels (OILs) for severe nuclear power plant or spent fuel pool emergencies.

    PubMed

    McKenna, T; Kutkov, V; Vilar Welter, P; Dodd, B; Buglova, E

    2013-05-01

    Experience and studies show that for an emergency at a nuclear power plant involving severe core damage or damage to the fuel in spent fuel pools, the following actions may need to be taken in order to prevent severe deterministic health effects and reduce stochastic health effects: (1) precautionary protective actions and other response actions for those near the facility (i.e., within the zones identified by the International Atomic Energy Agency) taken immediately upon detection of facility conditions indicating possible severe damage to the fuel in the core or in the spent fuel pool; and (2) protective actions and other response actions taken based on environmental monitoring and sampling results following a release. This paper addresses the second item by providing default operational intervention levels [OILs, which are similar to the U.S. derived response levels (DRLs)] for promptly assessing radioactive material deposition, as well as skin, food, milk and drinking water contamination, following a major release of fission products from the core or spent fuel pool of a light water reactor (LWR) or a high power channel reactor (RBMK), based on the International Atomic Energy Agency's guidance.

  12. Horizontal Steam Generator Thermal-Hydraulics at Various Steady-State Power Levels

    SciTech Connect

    Stevanovic, Vladimir D.; Stosic, Zoran V.; Kiera, Michael; Stoll, Uwe

    2002-07-01

    Three-dimensional computer simulation and analyses of the horizontal steam generator thermal-hydraulics of the WWER 1000 nuclear power plant have been performed for 50% and 75% partial loads, 100% nominal load and 110% over-load. Presented results show water and steam mass flow rate vectors, steam void fraction spatial distribution, recirculation zones, swell level position, water mass inventory on the shell side, and other important thermal-hydraulic parameters. The simulations have been performed with the computer code 3D ANA, based on the 'two-fluid' model approach. Steam-water interface transport processes, as well as tube bundle flow resistance, energy transfer, and steam generation within tube bundles are modelled with {sup c}losure laws{sup .} Applied approach implies non-equilibrium thermal and flow conditions. The model is solved by the control volume procedure, which has been extended in order to take into account the 3D flow of liquid and gas phase. The methodology is validated by comparing numerical and experimental results of real steam generator operational conditions at various power levels of the WWER Novovoronezh, Unit 5. One-dimensional model of the horizontal steam generator has been built with the RELAP 5 standard code on the basis of the multidimensional two-phase flow structure obtained with the 3D ANA code. RELAP 5 and 3D ANA code results are compared, showing acceptable agreement. (authors)

  13. Development Efforts Expanded in Ion Propulsion: Ion Thrusters Developed With Higher Power Levels

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Rawlin, Vincent K.; Sovey, James S.

    2003-01-01

    The NASA Glenn Research Center was the major contributor of 2-kW-class ion thruster technology to the Deep Space 1 mission, which was successfully completed in early 2002. Recently, NASA s Office of Space Science awarded approximately $21 million to Glenn to develop higher power xenon ion propulsion systems for large flagship missions such as outer planet explorers and sample return missions. The project, referred to as NASA's Evolutionary Xenon Thruster (NEXT), is a logical follow-on to the ion propulsion system demonstrated on Deep Space 1. The propulsion system power level for NEXT is expected to be as high as 25 kW, incorporating multiple ion thrusters, each capable of being throttled over a 1- to 6-kW power range. To date, engineering model thrusters have been developed, and performance and plume diagnostics are now being documented. The project team-Glenn, the Jet Propulsion Laboratory, General Dynamics, Boeing Electron Dynamic Devices, the Applied Physics Laboratory, the University of Michigan, and Colorado State University-is in the process of developing hardware for a ground demonstration of the NEXT propulsion system, which comprises a xenon feed system, controllers, multiple thrusters, and power processors. The development program also will include life assessments by tests and analyses, single-string tests of ion thrusters and power systems, and finally, multistring thruster system tests in calendar year 2005. In addition, NASA's Office of Space Science selected Glenn to lead the development of a 25-kW xenon thruster to enable NASA to conduct future missions to the outer planets of Jupiter and beyond, under the High Power Electric Propulsion (HiPEP) program. The development of a 100-kW-class ion propulsion system and power conversion systems are critical components to enable future nuclear-electric propulsion systems. In fiscal year 2003, a team composed of Glenn, the Boeing Company, General Dynamics, the Applied Physics Laboratory, the Naval Research

  14. On-chip power-combining techniques for watt-level linear power amplifiers in 0.18 μm CMOS

    NASA Astrophysics Data System (ADS)

    Zhixiong, Ren; Kefeng, Zhang; Lanqi, Liu; Cong, Li; Xiaofei, Chen; Dongsheng, Liu; Zhenglin, Liu; Xuecheng, Zou

    2015-09-01

    Three linear CMOS power amplifiers (PAs) with high output power (more than watt-level output power) for high data-rate mobile applications are introduced. To realize watt-level output power, there are two 2.4 GHz PAs using an on-chip parallel combining transformer (PCT) and one 1.95 GHz PA using an on-chip series combining transformer (SCT) to combine output signals of multiple power stages. Furthermore, some linearization techniques including adaptive bias, diode linearizer, multi-gated transistors (MGTR) and the second harmonic control are applied in these PAs. Using the proposed power combiner, these three PAs are designed and fabricated in TSMC 0.18 μm RFCMOS process. According to the measurement results, the proposed two linear 2.4 GHz PAs achieve a gain of 33.2 dB and 34.3 dB, a maximum output power of 30.7 dBm and 29.4 dBm, with 29% and 31.3% of peak PAE, respectively. According to the simulation results, the presented linear 1.95 GHz PA achieves a gain of 37.5 dB, a maximum output power of 34.3 dBm with 36.3% of peak PAE. Project supported by the National Natural Science Foundation of China (No. 61076030).

  15. Acoustic positioning using a tetrahedral ultrashort baseline array of an acoustic modem source transmitting frequency-hopped sequences.

    PubMed

    Beaujean, Pierre-Philippe J; Mohamed, Asif I; Warin, Raphael

    2007-01-01

    Acoustic communications and positioning are vital aspects of unmanned underwater vehicle operations. The usage of separate units on each vehicle has become an issue in terms of frequency bandwidth, space, power, and cost. Most vehicles rely on acoustic modems transmitting frequency-hopped multiple frequency-shift keyed sequences for command-and-control operations, which can be used to locate the vehicle with a good level of accuracy without requiring extra signal transmission. In this paper, an ultrashort baseline acoustic positioning technique has been designed, simulated, and tested to locate an acoustic modem source in three dimensions using a tetrahedral, half-wavelength acoustic antenna. The position estimation is performed using the detection sequence contained in each message, which is a series of frequency-hopped pulses. Maximum likelihood estimation of azimuth and elevation estimation is performed using a varying number of pulse and various signal-to-noise ratios. Simulated and measured position estimation error match closely, and indicate that the accuracy of this system improves dramatically as the number of pulses processed increases, given a fixed signal-to-noise ratio.

  16. 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.

  17. 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.

  18. Feasibility of making sound power measurements in the NASA Langley V/STOL tunnel test section

    NASA Technical Reports Server (NTRS)

    Brooks, T. F.; Scheiman, J.; Silcox, R. J.

    1976-01-01

    Based on exploratory acoustic measurements in Langley's V/STOL wind tunnel, recommendations are made on the methodology for making sound power measurements of aircraft components in the closed tunnel test section. During airflow, tunnel self-noise and microphone flow-induced noise place restrictions on the amplitude and spectrum of the sound source to be measured. Models of aircraft components with high sound level sources, such as thrust engines and powered lift systems, seem likely candidates for acoustic testing.

  19. Sound attenuation using microelectromechanical systems fabricated acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    Yunker, William N.; Stevens, Colin B.; Flowers, George T.; Dean, Robert N.

    2013-01-01

    Unlike traditional rotational gyroscopes, microelectromechanical systems (MEMS) gyroscopes use a vibrating proof mass rather than a rotational mass to sense changes in angular rate. They are also smaller and less expensive than traditional gyroscopes. MEMS gyroscopes are known to be susceptible to the effects of acoustic noise, in particular high frequency and high power acoustic noise. Most notably, this has been proven true in aerospace applications where the noise can reach levels in excess of 120 dB and the noise frequency can exceed 20 kHz. The typical resonant frequency for the proof mass of a MEMS gyroscope is between 3 and 20 kHz. High power, high frequency acoustic noise can disrupt the output signal of the gyroscope to the point that the output becomes unreliable. In recent years, considerable research has focused on the fascinating properties found in metamaterials. A metamaterial is an artificially fabricated device or structure that is engineered to produce desired material responses that can either mimic known behaviors or produce responses that do not occur naturally in materials found in nature. Acoustic metamaterials, in particular, have shown great promise in the field of sound attenuation. This paper proposes a method to mitigate the performance degradation of the MEMS gyroscope in the presence of high power, high frequency acoustic noise by using a new acoustic metamaterial in the form of a two-dimensional array of micromachined Helmholtz resonators. The Helmholtz resonators are fabricated in a silicon wafer using standard MEMS manufacturing techniques and are designed to attenuate sound at the resonant frequency of the gyroscope proof mass. The resonator arrays were diced from the silicon wafer in one inch squares and assembled into a box open on one end in a manner to attenuate sound on all sides of the gyroscope, and to seal the gyroscope inside the box. The resulting acoustic metamaterial device was evaluated in an acoustic chamber and was

  20. Characterizing the cavitation development and acoustic spectrum in various liquids.

    PubMed

    Tzanakis, I; Lebon, G S B; Eskin, D G; Pericleous, K A

    2017-01-01

    A bespoke cavitometer that measures acoustic spectrum and is capable of operating in a range of temperatures (up to 750°C) was used to study the cavitation behaviour in three transparent liquids and in molten aluminium. To relate these acoustic measurements to cavitation development, the dynamics of the cavitation bubble structures was observed in three Newtonian, optically transparent liquids with significantly different physical properties: water, ethanol, and glycerine. Each liquid was treated at 20kHz with a piezoelectric ultrasonic transducer coupled to a titanium sonotrode with a tip diameter of 40mm. Two different transducer power levels were deployed: 50% and 100%, with the maximum power corresponding to a peak-to-peak amplitude of 17μm. The cavitation structures and the flow patterns were filmed with a digital camera. To investigate the effect of distance from the ultrasound source on the cavitation intensity, acoustic emissions were measured with the cavitometer at two points: below the sonotrode and near the edge of the experimental vessel. The behaviour of the three tested liquids was very different, implying that their physical parameters played a decisive role in the establishment of the cavitation regime. Non dimensional analysis revealed that water shares the closest cavitation behaviour with liquid aluminium and can therefore be used as its physical analogue in cavitation studies; this similarity was also confirmed when comparing the measured acoustic spectra of water and liquid aluminium.

  1. 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.

  2. Accelerated testing of module-level power electronics for long-term reliability

    SciTech Connect

    Flicker, Jack David; Tamizhmani, Govindasamy; Moorthy, Mathan Kumar; Thiagarajan, Ramanathan; Ayyanar, Raja

    2016-11-10

    This work has applied a suite of long-term-reliability accelerated tests to a variety of module-level power electronics (MLPE) devices (such as microinverters and optimizers) from five different manufacturers. This dataset is one of the first (only the paper by Parker et al. entitled “Dominant factors affecting reliability of alternating current photovoltaic modules,” in Proc. 42nd IEEE Photovoltaic Spec. Conf., 2015, is reported for reliability testing in the literature), as well as the largest, experimental sets in public literature, both in the sample size (five manufacturers including both dc/dc and dc/ac units and 20 units for each test) and the number of experiments (six different experimental test conditions) for MLPE devices. The accelerated stress tests (thermal cycling test per IEC 61215 profile, damp heat test per IEC 61215 profile, and static temperature tests at 100 and 125 °C) were performed under powered and unpowered conditions. The first independent long-term experimental data regarding damp heat and grid transient testing, as well as the longest term (>9 month) testing of MLPE units reported in the literature for thermal cycling and high-temperature operating life, are included in these experiments. Additionally, this work is the first to show in situ power measurements, as well as periodic efficiency measurements over a series of experimental tests, demonstrating whether certain tests result in long-term degradation or immediate catastrophic failures. Lastly, the result of this testing highlights the performance of MLPE units under the application of several accelerated environmental stressors.

  3. Fourier Power Spectrum Characteristics of Face Photographs: Attractiveness Perception Depends on Low-Level Image Properties

    PubMed Central

    Langner, Oliver; Wiese, Holger; Redies, Christoph

    2015-01-01

    We investigated whether low-level processed image properties that are shared by natural scenes and artworks – but not veridical face photographs – affect the perception of facial attractiveness and age. Specifically, we considered the slope of the radially averaged Fourier power spectrum in a log-log plot. This slope is a measure of the distribution of special frequency power in an image. Images of natural scenes and artworks possess – compared to face images – a relatively shallow slope (i.e., increased high spatial frequency power). Since aesthetic perception might be based on the efficient processing of images with natural scene statistics, we assumed that the perception of facial attractiveness might also be affected by these properties. We calculated Fourier slope and other beauty-associated measurements in face images and correlated them with ratings of attractiveness and age of the depicted persons (Study 1). We found that Fourier slope – in contrast to the other tested image properties – did not predict attractiveness ratings when we controlled for age. In Study 2A, we overlaid face images with random-phase patterns with different statistics. Patterns with a slope similar to those in natural scenes and artworks resulted in lower attractiveness and higher age ratings. In Studies 2B and 2C, we directly manipulated the Fourier slope of face images and found that images with shallower slopes were rated as more attractive. Additionally, attractiveness of unaltered faces was affected by the Fourier slope of a random-phase background (Study 3). Faces in front of backgrounds with statistics similar to natural scenes and faces were rated as more attractive. We conclude that facial attractiveness ratings are affected by specific image properties. An explanation might be the efficient coding hypothesis. PMID:25835539

  4. Accelerated testing of module-level power electronics for long-term reliability

    DOE PAGES

    Flicker, Jack David; Tamizhmani, Govindasamy; Moorthy, Mathan Kumar; ...

    2016-11-10

    This work has applied a suite of long-term-reliability accelerated tests to a variety of module-level power electronics (MLPE) devices (such as microinverters and optimizers) from five different manufacturers. This dataset is one of the first (only the paper by Parker et al. entitled “Dominant factors affecting reliability of alternating current photovoltaic modules,” in Proc. 42nd IEEE Photovoltaic Spec. Conf., 2015, is reported for reliability testing in the literature), as well as the largest, experimental sets in public literature, both in the sample size (five manufacturers including both dc/dc and dc/ac units and 20 units for each test) and the numbermore » of experiments (six different experimental test conditions) for MLPE devices. The accelerated stress tests (thermal cycling test per IEC 61215 profile, damp heat test per IEC 61215 profile, and static temperature tests at 100 and 125 °C) were performed under powered and unpowered conditions. The first independent long-term experimental data regarding damp heat and grid transient testing, as well as the longest term (>9 month) testing of MLPE units reported in the literature for thermal cycling and high-temperature operating life, are included in these experiments. Additionally, this work is the first to show in situ power measurements, as well as periodic efficiency measurements over a series of experimental tests, demonstrating whether certain tests result in long-term degradation or immediate catastrophic failures. Lastly, the result of this testing highlights the performance of MLPE units under the application of several accelerated environmental stressors.« less

  5. Fourier power spectrum characteristics of face photographs: attractiveness perception depends on low-level image properties.

    PubMed

    Menzel, Claudia; Hayn-Leichsenring, Gregor U; Langner, Oliver; Wiese, Holger; Redies, Christoph

    2015-01-01

    We investigated whether low-level processed image properties that are shared by natural scenes and artworks - but not veridical face photographs - affect the perception of facial attractiveness and age. Specifically, we considered the slope of the radially averaged Fourier power spectrum in a log-log plot. This slope is a measure of the distribution of special frequency power in an image. Images of natural scenes and artworks possess - compared to face images - a relatively shallow slope (i.e., increased high spatial frequency power). Since aesthetic perception might be based on the efficient processing of images with natural scene statistics, we assumed that the perception of facial attractiveness might also be affected by these properties. We calculated Fourier slope and other beauty-associated measurements in face images and correlated them with ratings of attractiveness and age of the depicted persons (Study 1). We found that Fourier slope - in contrast to the other tested image properties - did not predict attractiveness ratings when we controlled for age. In Study 2A, we overlaid face images with random-phase patterns with different statistics. Patterns with a slope similar to those in natural scenes and artworks resulted in lower attractiveness and higher age ratings. In Studies 2B and 2C, we directly manipulated the Fourier slope of face images and found that images with shallower slopes were rated as more attractive. Additionally, attractiveness of unaltered faces was affected by the Fourier slope of a random-phase background (Study 3). Faces in front of backgrounds with statistics similar to natural scenes and faces were rated as more attractive. We conclude that facial attractiveness ratings are affected by specific image properties. An explanation might be the efficient coding hypothesis.

  6. A General Framework for Power Analysis to Detect the Moderator Effects in Two- and Three-Level Cluster Randomized Trials

    ERIC Educational Resources Information Center

    Dong, Nianbo; Spybrook, Jessaca; Kelcey, Ben

    2016-01-01

    The purpose of this study is to propose a general framework for power analyses to detect the moderator effects in two- and three-level cluster randomized trials (CRTs). The study specifically aims to: (1) develop the statistical formulations for calculating statistical power, minimum detectable effect size (MDES) and its confidence interval to…

  7. 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.}

  8. Medical Acoustics

    NASA Astrophysics Data System (ADS)

    Beach, Kirk W.; 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.

  9. Efficiency at maximum power of a heat engine working with a two-level atomic system

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Wang, Jianhui; He, Jizhou; Ma, Yongli

    2013-04-01

    We consider the finite-time operation of a quantum heat engine whose working substance is composed of a two-level atomic system. The engine cycle, consisting of two quantum adiabatic and two quantum isochoric (constant-frequency) processes and working between two heat reservoirs at temperatures Th and Tc(power output with respect to two frequencies, we obtain the efficiency at maximum power output (EMP) and analyze numerically the effects of the times taken for two adiabatic and two isochoric processes on the EMP. In the absence of internally dissipative friction, we find that the EMP is bounded from the upper side by a function of the Carnot efficiency ηC, η+=ηC2/[ηC-(1-ηC)ln(1-ηC)], with ηC=1-Tc/Th. This analytic expression is confirmed by our exact numerical result and is identical to the one derived in an engine model based on a mesoscopic or macroscopic system. If the internal friction is included, we find that the EMP decreases as the friction coefficient increases.

  10. Acoustic characteristics of large-scale STOL model at forward speed

    NASA Technical Reports Server (NTRS)

    Falarski, M. D.; Aoyagi, K.; Koenig, D. G.

    1972-01-01

    Wind-tunnel investigations of the acoustic characteristics of the externally blown jet flap (EBF) and augmentor wing STOL concepts are dicussed. The large-scale EBF model was equipped with a triple-slotted blown by four JT15D turbofan engines with circular, coannular exhaust nozzles. The large-scale augmentor wing model was equipped with an unlined augmentor blown by a slot primary nozzle. The effects of airspeed and angle of attack on the acoustics of the EBF were small. At a forward speed of 60 knots, the impingement noise of the landing flap was approximately 2 db lower than in the static tests. Angle of attack increased the impingement noise approximately 0.1 decibels per degree. Flap deflection had a greater effect on the acoustics of the augmentor wing than did airspeed. For a nozzle pressure ratio of 1.9, the peak perceived noise level of the landing flap was 3 to 5 PNdb higher than that of the takeoff flap. The total sound power was also significantly higher for landing indicating that turning in the augmentor generated acoustic energy. Airspeed produced a small aft shift in acoustic directivity with no significant change in the peak perceived noise levels or sound power levels.

  11. A vibroseismic method for estimation of the ecological risk of powerful technogenic and natural explosions

    NASA Astrophysics Data System (ADS)

    Khairetdinov, Marat; Voskoboynikova, Gyulnara; Sedukhina, Galina

    2016-04-01

    This paper presents the results of experimental investigations of an original ecologically safe approach, proposed by the authors, to assessment of the geoecological risk from powerful mass explosions for the social and natural environment. In this approach, seismic vibrators are used as sources imitating explosions but having, in contrast to them, a much smaller power. Such sources can simultaneously excite in the medium seismic and acoustic (vibro-seismo-acoustic) oscillations with precision power and frequency-time characteristics. A comparative analysis of seismic and acoustic wave levels allows us to conclude that the major ecologically dangerous effect of ground-based test site explosions is due to acoustic waves whose energy is an order of magnitude greater than that of seismic waves. Calculated azimuthal dependencies of the focusing effect of acoustic waves in the infralow frequency range at different wind velocities and "source-receiver" distances by vibrator CV-40 were obtained . It was found that meteorological conditions have a greater influence on acoustic wave focusing in experiments that according to theoretical results. The effects of focusing of acoustic oscillations in space were revealed and estimated quantitatively. Specifically, it was proved that even at a weak wind of 2-4 m/s the ratio between the maximal and minimal acoustic wave levels depending on the azimuthal direction can reach 50. This can be a reason for great ecological hazard of technogenic explosions. The received results are new and original. The received results are new and original.

  12. Acoustic dose and acoustic dose-rate.

    PubMed

    Duck, Francis

    2009-10-01

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

  13. Four Key Keys to Powerful Presentations in PowerPoint: Take Your Presentations to the Next Level

    ERIC Educational Resources Information Center

    Howell, Dusti D.

    2008-01-01

    If a person is on a presentation and he/she does not know how to go back to a previous PowerPoint slide, his/her credibility will be clouded and the audience will become frustrated. More sophisticated presenters use handheld remotes to control the basic navigation of slides. Even in this case, keyboard shortcuts can be an added benefit. For those…

  14. Acoustic Microscopy at Cryogenic Temperatures.

    DTIC Science & Technology

    1982-01-01

    intensities are used, and quantitatitvely acount for the onset of nonlinear excess attenuation. Aooeuuaiol For DTIC TAB Unaranounc ed Just if icat to By...to acoustic power is a reasonable value and can be acounted for by assuming a one-way transducer conversion loss of 5 dB, a lens illumination loss of

  15. 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.

  16. Influence of Strength Level on the Rest Interval Required During an Upper-Body Power Training Session.

    PubMed

    Hernández Davó, Jose Luis; Botella Ruiz, Javier; Sabido, Rafael

    2017-02-01

    Hernández Davó, JL, Botella Ruiz, J, and Sabido, R. Influence of strength level on the rest interval required during an upper-body power training session. J Strength Cond Res 31(2): 339-347, 2017-The present study aimed to investigate the influence of subjects' strength level on both the ability to maintain power output performance and the physiological and perceived exertion responses during a power training session when different rest intervals (RI) are used. Thirty-eight (18 men and 20 women) subjects were divided into a stronger or weaker group based on their ability to produce peak power output. Testing was performed using the same protocol (5 sets of 8 repetitions with 40% of 1 repetition maximum) in the bench press throw exercise, but differing the RI between sets (1, 2, and 3 minutes). During the sessions, mechanical (peak power), physiological ([La]) and perceptual (RPE) variables were measured. In addition, delayed onset muscular soreness (DOMS) 24 and 48 hours after the training session was reported. Both stronger and weaker (men and women) groups showed significant impairments in mechanical, physiological, and perceptual data when resting 1 minute. Nevertheless, although stronger groups were able to sustain power output over the sets when using the 2-minute RI, weaker groups needed at least 3 minutes to maintain power output performance. Therefore, strength level heavily influences the rest interval required during a power training session and should be taken into account when prescribing such training sessions.

  17. Acoustic mechanical feedthroughs

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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

  18. 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

  19. Coupling between plate vibration and acoustic radiation

    NASA Technical Reports Server (NTRS)

    Frendi, Abdelkader; Maestrello, Lucio; Bayliss, Alvin

    1992-01-01

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

  20. Coupling between plate vibration and acoustic radiation

    NASA Technical Reports Server (NTRS)

    Frendi, Abdelkader; Maestrello, Lucio; Bayliss, Alvin

    1993-01-01

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

  1. Acoustic scattering by a spliced turbofan inlet duct liner at supersonic fan speeds

    NASA Astrophysics Data System (ADS)

    McAlpine, A.; Wright, M. C. M.

    2006-05-01

    Fan noise is one of the principal noise sources generated by a turbofan aero-engine. At supersonic fan speeds, fan tones are generated by the "rotor-alone" pressure field. In general, these tones can be well absorbed by an inlet duct acoustic liner, apart from at high supersonic fan speeds. However, in practice inlet duct liners contain acoustically hard longitudinal splices which cause scattering. This leads to acoustic energy being scattered into a range of different azimuthal mode orders, similar to the modal content resulting from rotor-stator interactions. The effectiveness of an inlet duct lining is reduced because acoustic energy is scattered into modes that are poorly absorbed by the liner. In this article, the effect of this acoustic scattering is examined by three-dimensional finite-element simulations of sound transmission in a turbofan inlet duct. Results include predictions of the sound power transmission loss with different splice widths, and at different supersonic fan speeds. These results demonstrate how acoustic scattering by liner splices can adversely affect fan tone noise levels at low supersonic fan speeds, but have little adverse affect on noise levels at high supersonic fan speeds. The potential noise benefit that could be achieved by manufacturing thinner splices is also examined.

  2. Power enhancement of heat engines via correlated thermalization in a three-level “working fluid”

    PubMed Central

    Gelbwaser-Klimovsky, David; Niedenzu, Wolfgang; Brumer, Paul; Kurizki, Gershon

    2015-01-01

    We explore means of maximizing the power output of a heat engine based on a periodically-driven quantum system that is constantly coupled to hot and cold baths. It is shown that the maximal power output of such a heat engine whose “working fluid” is a degenerate V-type three-level system is that generated by two independent two-level systems. Hence, level degeneracy is a thermodynamic resource that may effectively double the power output. The efficiency, however, is not affected. We find that coherence is not an essential asset in such multilevel-based heat engines. The existence of two thermalization pathways sharing a common ground state suffices for power enhancement. PMID:26394838

  3. Acoustics Research of Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Gao, Ximing; Houston, Janice

    2014-01-01

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

  4. Alteration of consciousness via diverse photo-acoustic stimulatory patterns. Phenomenology and effect on salivary flow rate, alpha-amylase and total protein levels.

    PubMed

    Beck, Anita; Fábián, Gábor; Fejérdy, Pál; Krause, Wolf-Rainer; Hermann, Péter; Módos, Károly; Varga, Gábor; Fábián, Tibor Károly

    2015-12-01

    Long-term photo-acoustic stimulation is used for the induction of altered states of consciousness for both therapeutic and experimental purposes. Long-term photo-acoustic stimulation also leads to changes in the composition of saliva which have a key contribution to the efficiency of this technique in easing mucosal symptoms of oral psychosomatic patients. The aim of this study is to find out whether there is any cumulative effect of repeated stimulation and whether there are any detectable differences between diverse stimulatory patterns of long lasting photo-acoustic stimulation on the phenomenology of the appearing trance state and on salivary secretion. There was significant cumulative effect in relation with the appearance of day dreaming as phenomenological parameter, and in relation with protein output and amylase/protein ratio as salivary parameter. Pattern specific effect was detectable in relation with salivary flow rate only. Although our results clearly indicate the existence of certain cumulative and stimulation-pattern specific effects of repeated photo-acoustic stimulation, the absolute values of all these effects were relatively small in this study. Therefore, in spite of their theoretical importance there are no direct clinical consequences of these findings. However, our data do not exclude at all the possibility that repeated stimulation with other stimulatory parameters may lead to more pronounced effects. Further studies are needed to make clear conclusion in this respect.

  5. Dose estimation for nuclear power plant 4 accident in Taiwan at Fukushima nuclear meltdown emission level.

    PubMed

    Tang, Mei-Ling; Tsuang, Ben-Jei; Kuo, Pei-Hsuan

    2016-05-01

    An advanced Gaussian trajectory dispersion model is used to evaluate the evacuation zone due to a nuclear meltdown at the Nuclear Power Plant 4 (NPP4) in Taiwan, with the same emission level as that occurred at Fukushima nuclear meltdown (FNM) in 2011. Our study demonstrates that a FNM emission level would pollute 9% of the island's land area with annual effective dose ≥50 mSv using the meteorological data on 11 March 2011 in Taiwan. This high dose area is also called permanent evacuation zone (denoted as PEZ). The PEZ as well as the emergency-planning zone (EPZ) are found to be sensitive to meteorological conditions on the event. In a sunny day under the dominated NE wind conditions, the EPZ can be as far as 100 km with the first 7-day dose ≥20 mSv. Three hundred sixty-five daily events using the meteorological data from 11 March 2011 to 9 March 2012 are evaluated. It is found that the mean land area of Taiwan in becoming the PEZ is 11%. Especially, the probabilities of the northern counties/cities (Keelung, New Taipei, Taipei, Taoyuan, Hsinchu City, Hsinchu County and Ilan County) to be PEZs are high, ranging from 15% in Ilan County to 51% in Keelung City. Note that the total population of the above cities/counties is as high as 10 million people. Moreover, the western valleys of the Central Mountain Range are also found to be probable being PEZs, where all of the reservoirs in western Taiwan are located. For example, the probability can be as high as 3% in the far southern-most tip of Taiwan Island in Pingtung County. This shows that the entire populations in western Taiwan can be at risk due to the shortage of clean water sources under an event at FNM emission level, especially during the NE monsoon period.

  6. Acoustics Research of Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Gao, Ximing; Houston, Janice D.

    2014-01-01

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

  7. Properties of acoustic sources in the Sun

    NASA Technical Reports Server (NTRS)

    Kumar, Pawan

    1994-01-01

    The power spectrum of solar acoustic oscillations shows peaks extending out to frequencies much greater than the acoustic cutoff frequency of approximately 5.3 mHz, where waves are no longer trapped. Kumar & Lu (1991) proposed that these peaks arise from the interference of traveling waves which are generated by turbulent convection. According to this model, the frequencies of the peaks in the power spectrum depend on the static structure of the Sun as well as the radial location of the sources. Kumar & Lu used this idea to determine the depth of the acoustic sources. However, they ignored dissipative effects and found that the theoretically computed power spectrum was falling off much more rapidly than the observed spectrum. In this paper, we include the interaction of radiation with acoustic waves in the computation of the power spectrum. We find that the theoretically calculated power spectra, when radiative damping is included are in excellent agreement with the observed power spectra over the entire observed frequency range of 5.3 to 7.5 mHz above the acoustic cutoff frequency. Moreover, by matching the peak frequencies in the observed and theoretical spectra we find the mean depth of acoustic sources to be 140 +/- 60 km below the photosphere. We show that the spectrum of solar turbulence near the top of the solar convection zone is consistent with the Kolmogorov spectrum, and that the observed high frequency power spectrum provides strong evidence that the acoustic sources in the Sun are quadrupolar. The data, in fact, rules out dipole sources as significant contributors to acoustic wave generation in the Sun. The radial extent of the sources is poorly determined and is estimated to be less than about 550 km.

  8. Transmural heterogeneity of cellular level power output is reduced in human heart failure

    PubMed Central

    Haynes, Premi; Nava, Kristofer E.; Lawson, Benjamin A.; Chung, Charles S.; Mitov, Mihail I.; Campbell, Stuart G.; Stromberg, Arnold J.; Sadayappan, Sakthivel; Bonnell, Mark R.; Hoopes, Charles W.; Campbell, Kenneth S.

    2014-01-01

    Heart failure is associated with pump dysfunction and remodeling but it is not yet known if the condition affects different transmural regions of the heart in the same way. We tested the hypotheses that the left ventricles of non-failing human hearts exhibit transmural heterogeneity of cellular level contractile properties, and that heart failure produces transmural region-specific changes in contractile function. Permeabilized samples were prepared from the sub-epicardial, mid-myocardial, and sub-endocardial regions of the left ventricular free wall of non-failing (n=6) and failing (n=10) human hearts. Power, an in vitro index of systolic function, was higher in non-failing mid-myocardial samples (0.59±0.06 μW mg−1) than in samples from the sub-epicardium (p=0.021) and the sub-endocardium (p=0.015). Non-failing mid-myocardial samples also produced more isometric force (14.3±1.33 kN m−2) than samples from the sub-epicardium (p=0.008) and the sub-endocardium (p=0.026). Heart failure reduced power (p=0.009) and force (p=0.042) but affected the mid-myocardium more than the other transmural regions. Fibrosis increased with heart failure (p=0.021) and mid-myocardial tissue from failing hearts contained more collagen than matched sub-epicardial (p<0.001) and sub-endocardial (p=0.043) samples. Power output was correlated with the relative content of actin and troponin I, and was also statistically linked to the relative content and phosphorylation of desmin and myosin light chain- 1. Non-failing human hearts exhibit transmural heterogeneity of contractile properties. In failing organs, region-specific fibrosis produces the greatest contractile deficits in the mid-myocardium. Targeting fibrosis and sarcomeric proteins in the mid-myocardium may be particularly effective therapies for heart failure. PMID:24560668

  9. Leveling the Field: Negotiating Positions of Power as a Preservice Teacher

    ERIC Educational Resources Information Center

    Vetter, Amy; Meacham, Mark; Schieble, Melissa

    2013-01-01

    Set in an undergraduate Secondary English Education Program, this qualitative study draws on theories of power, positioning, and identity to explore how positions of power affect teacher identity construction. Drawn from a larger study, the authors examine how one preservice teacher negotiated positions of power with students in ways that enabled…

  10. Characterization of a multi-element clinical HIFU system using acoustic holography and nonlinear modeling.

    PubMed

    Kreider, Wayne; Yuldashev, Petr V; Sapozhnikov, Oleg A; Farr, Navid; Partanen, Ari; Bailey, Michael R; Khokhlova, Vera A

    2013-08-01

    High-intensity focused ultrasound (HIFU) is a treatment modality that relies on the delivery of acoustic energy to remote tissue sites to induce thermal and/or mechanical tissue ablation. To ensure the safety and efficacy of this medical technology, standard approaches are needed for accurately characterizing the acoustic pressures generated by clinical ultrasound sources under operating conditions. Characterization of HIFU fields is complicated by nonlinear wave propagation and the complexity of phased-array transducers. Previous work has described aspects of an approach that combines measurements and modeling, and here we demonstrate this approach for a clinical phased-array transducer. First, low amplitude hydrophone measurements were performed in water over a scan plane between the array and the focus. Second, these measurements were used to holographically reconstruct the surface vibrations of the transducer and to set a boundary condition for a 3-D acoustic propagation model. Finally, nonlinear simulations of the acoustic field were carried out over a range of source power levels. Simulation results were compared with pressure waveforms measured directly by hydrophone at both low and high power levels, demonstrating that details of the acoustic field, including shock formation, are quantitatively predicted.

  11. Characterization of a Multi-element Clinical HIFU System Using Acoustic Holography and Nonlinear Modeling

    PubMed Central

    Kreider, Wayne; Yuldashev, Petr V.; Sapozhnikov, Oleg A.; Farr, Navid; Partanen, Ari; Bailey, Michael R.; Khokhlova, Vera A.

    2014-01-01

    High-intensity focused ultrasound (HIFU) is a treatment modality that relies on the delivery of acoustic energy to remote tissue sites to induce thermal and/or mechanical tissue ablation. To ensure the safety and efficacy of this medical technology, standard approaches are needed for accurately characterizing the acoustic pressures generated by clinical ultrasound sources under operating conditions. Characterization of HIFU fields is complicated by nonlinear wave propagation and the complexity of phased-array transducers. Previous work has described aspects of an approach that combines measurements and modeling, and here we demonstrate this approach for a clinical phased array transducer. First, low-amplitude hydrophone measurements were performed in water over a scan plane between the array and the focus. Second, these measurements were used to holographically reconstruct the surface vibrations of the transducer and to set a boundary condition for a 3-D acoustic propagation model. Finally, nonlinear simulations of the acoustic field were carried out over a range of source power levels. Simulation results were compared to pressure waveforms measured directly by hydrophone at both low and high power levels, demonstrating that details of the acoustic field including shock formation are quantitatively predicted. PMID:25004539

  12. Ordering Power of Separate versus Grouped True-False Tests: Interaction of Type of Test with Knowledge Levels of Examinees.

    ERIC Educational Resources Information Center

    Hsu, Louis M.

    1979-01-01

    A comparison of the relative ordering power of separate and grouped-items true-false tests indicated that neither type of test was uniformly superior to the other across all levels of knowledge of examinees. Grouped-item tests were found superior for examinees with low levels of knowledge. (Author/CTM)

  13. Acoustic methodology review

    NASA Technical Reports Server (NTRS)

    Schlegel, R. G.

    1982-01-01

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

  14. Suppression through acoustics

    NASA Astrophysics Data System (ADS)

    Beck, Kevin D.; Short, Kenneth R.; VanMeenen, Kirsten M.; Servatius, Richard J.

    2006-05-01

    This paper reviews research conducted by our laboratory exploring the possible use of acoustical stimuli as a tool for influencing behavior. Over the course of several programs, different types of acoustic stimuli have been evaluated for their effectiveness in disrupting targeting, balance, and high-order cognitive processes in both humans and animals. Escape responses are of particular use in this regard. An escape response serves not only as an objective measure of aversion, but as a potential substitute for ongoing behavior. We have also assessed whether the level of performance changes if the individual does not perform an escape response. In general these studies have both suggested certain types of sounds are more aversive or distracting than others. Although the laboratory development of additional stimuli needs to continue, we are taking the next step by testing some of the more effective stimuli in more applied experimental scenarios including those involving group dynamics.

  15. Levels of community engagement in youth violence prevention: the role of power in sustaining successful university-community partnerships.

    PubMed

    Nation, Maury; Bess, Kimberly; Voight, Adam; Perkins, Douglas D; Juarez, Paul

    2011-09-01

    Previous research indicates that communities can be engaged at various levels in research to reduce youth violence. In this paper, we argue that the method of power sharing among partners is a central factor distinguishing different levels of engagement. Using cases from the Nashville Urban Partnership Academic Center of Excellence, we identify community initiation and community collaboration as distinct approaches to community engaged violence prevention research. The power relationships among partners are analyzed to highlight differences in the types of engagement and to discuss implications for establishing and sustaining community partnerships. Also, the implications of levels of engagement for promoting the use of evidence-based practices are discussed.

  16. 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

  17. 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.

  18. Passive mode-locking of fiber ring laser at the 337th harmonic using gigahertz acoustic core resonances.

    PubMed

    Kang, M S; Joly, N Y; Russell, P St J

    2013-02-15

    We report the experimental demonstration of a passively mode-locked Er-doped fiber ring laser operating at the 337th harmonic (1.80 GHz) of the cavity. The laser makes use of highly efficient Raman-like optoacoustic interactions between the guided light and gigahertz acoustic resonances trapped in the micron-sized solid glass core of a photonic crystal fiber. At sufficient pump power levels the laser output locks to a repetition rate corresponding to the acoustic frequency. A stable optical pulse train with a side-mode suppression ratio higher than 45 dB was obtained at low pump powers (~60 mW).

  19. Acoustic iridescence.

    PubMed

    Cox, Trevor J

    2011-03-01

    An investigation has been undertaken into acoustic iridescence, exploring how a device can be constructed which alter sound waves, in a similar way to structures in nature that act on light to produce optical iridescence. The main construction had many thin perforated sheets spaced half a wavelength apart for a specified design frequency. The sheets create the necessary impedance discontinuities to create backscattered waves, which then interfere to create strongly reflected sound at certain frequencies. Predictions and measurements show a set of harmonics, evenly spaced in frequency, for which sound is reflected strongly. And the frequency of these harmonics increases as the angle of observation gets larger, mimicking the iridescence seen in natural optical systems. Similar to optical systems, the reflections become weaker for oblique angles of reflection. A second construction was briefly examined which exploited a metamaterial made from elements and inclusions which were much smaller than the wavelength. Boundary element method predictions confirmed the potential for creating acoustic iridescence from layers of such a material.

  20. Low level measurements of natural radionuclides in soil samples around a coal-fired power plant

    NASA Astrophysics Data System (ADS)

    Rosner, G.; Bunzl, K.; Hötzl, H.; Winkler, R.

    1984-06-01

    To detect a possible contribution of airborne radioactivity from stack effluents to the soil radioactivity, several radionuclides in the soil around a coal-fired power plant have been determined. A plant situated in a rural region of Bavaria was selected to minimize contributions from other civilisatory sources. The soil sampling network consisted of 5 concentric circles with diameters between 0.4 and 5.2 km around the plant, 16 sampling points being distributed regularly on each circle. Radiochemical analysis techniques for 210Pb and 210Po in soil samples of several grams had to be developed. They include a wet dissolution procedure, simultaneous precipitation of lead and polonium as the sulfides, purification via lead sulfate, counting of the lead as the chromate in a low-level beta counter and alpha spectrometric determination of the 210Po in a gridded ionization chamber. The 238U, 226Ra, 232Th and 40K were counted by low level gamma spectrometry. Specific activities found were in the range of 0.7 to 2.0 pCi g -1 for 210Pb and 0.3 to 1.6 pCi g -1 for 226Ra. The distribution patterns of 210Po and 210Pb around the plant were found to be similar. They were different, however, from that of 226Ra. The highest 210Pb/ 226Ra activity ratio was 3.9 at a distance of 0.76 km SSE from the plant. Nevertheless, the evidence is not considered to be sufficient to attribute these observations unambiguously to plant releases.

  1. Comparison of Mental Toughness and Power Test Performances in High-Level Kickboxers by Competitive Success

    PubMed Central

    Slimani, Maamer; Miarka, Bianca; Briki, Walid; Cheour, Foued

    2016-01-01

    Background Kickboxing is a high-intensity intermittent striking combat sport, which is characterized by complex skills and tactical key actions with short duration. Objectives The present study compared and verified the relationship between mental toughness (MT), countermovement jump (CMJ) and medicine ball throw (MBT) power tests by outcomes of high-level kickboxers during National Championship. Materials and Methods Thirty two high-level male kickboxers (winner = 16 and loser = 16: 21.2 ± 3.1 years, 1.73 ± 0.07 m, and 70.2 ± 9.4 kg) were analyzed using the CMJ, MBT tests and sports mental toughness questionnaire (SMTQ; based in confidence, constancy and control subscales), before the fights of the 2015 national championship (16 bouts). In statistical analysis, Mann-Withney test and a multiple linear regression were used to compare groups and to observe relationships, respectively, P ≤ 0.05. Results The present results showed significant differences between losers vs. winners, respectively, of total MT (7(7;8) vs. 11(10.2;11), confidence (3(3;3) vs. 4(4;4)), constancy (2(2;2) vs. 3(3;3)), control (2(2;3) vs. 4(4;4)) subscales and MBT (4.1(4;4.3) vs. 4.6(4.4;4.8)). The multiple linear regression showed a strong associations between MT results and outcome (r = 0.89), MBT (r = 0.84) and CMJ (r = 0.73). Conclusions The findings suggest that MT will be more predictive of performance in those sports and in the outcome of competition. PMID:27625755

  2. Low-power laser effects at the single-cell level: a confocal microscopy study

    NASA Astrophysics Data System (ADS)

    Alexandratou, Eleni; Yova, Dido M.; Atlamazoglou, Vassilis; Handris, Panagiotis; Kletsas, Dimitris; Loukas, Spyros

    2000-11-01

    Confocal microscopy was used for irradiation and observation of the same area of interest, allowing the imaging of low power laser effects in subcellular components and functions, at the single cell level. Coverslips cultures of human fetal foreskin fibroblasts (HFFF2) were placed in a small incubation chamber for in vivo microscopic observation. Cells were stimulated by the 647 nm line of the Argon- Krypton laser of the confocal microscope (0.1 mW/cm2). Membrane permeability, mitochondrial membrane potential ((delta) Psim), intracellular pHi, calcium alterations and nuclear chromatin accessibility were monitored, at different times after irradiation, using specific fluorescent vital probes. Images were stored to the computer and quantitative evaluation was performed using image- processing software. After irradiation, influx and efflux of the appropriate dyes monitored changes in cell membrane permeability. Laser irradiation caused alkalizatoin of the cytosolic pHi and increase of the mitochondrial membrane potential ((delta) Psim). Temporary global Ca2+ responses were also observed. No such effects were noted in microscopic fields other than the irradiated ones. No toxic effects were observed, during time course of the experiment.

  3. 129I level in seawater near a nuclear power plant determined by accelerator mass spectrometer

    NASA Astrophysics Data System (ADS)

    He, Chaohui; Hou, Xiaolin; Zhao, Yaolin; Wang, Zhiwen; Li, Huaibin; Chen, Ning; Liu, Qi; Zhang, Luyuan; Luo, Maoyi; Liang, Wangguo; Fan, Yukun; Zhao, Xiaolei

    2011-03-01

    129I concentration in the seawater samples near a nuclear power plant was determined in the Xi'an Accelerator Mass Spectrometer (AMS) Center. Isotope dilution method was used via addition of excessive amount of stable iodine ( 127I) in the sample before separation, and iodine in the seawater was separated by solvent extraction, and the back extracted iodine in iodide form was precipitated as AgI, which was used as AMS target for 129I measurement. 125I tracer was added to monitor the recovery of iodine in the whole separation process. 129I/ 127I ratios in the prepared target were determined by AMS. The concentration of 127I in seawater samples was determined by inductively coupled plasma mass spectrometry. The results show that the 129I/ 127I atomic ratios in the seawater range from 8.29×10 -11 to 9.45×10 -10, approximately one order of magnitude higher than that in seaweed collected in the pre-nuclear era, but fall in the environmental level of global fallout.

  4. Mathematical explanation of the predictive power of the X-level approach reaction noise estimator method

    PubMed Central

    2012-01-01

    The X-level Approach Reaction Noise Estimator (XARNES) method has been developed previously to study reaction noise in well mixed reaction volumes. The method is a typical moment closure method and it works by closing the infinite hierarchy of equations that describe moments of the particle number distribution function. This is done by using correlation forms which describe correlation effects in a strict mathematical way. The variable X is used to specify which correlation effects (forms) are included in the description. Previously, it was argued, in a rather informal way, that the method should work well in situations where the particle number distribution function is Poisson-like. Numerical tests confirmed this. It was shown that the predictive power of the method increases, i.e. the agreement between the theory and simulations improves, if X is increased. In here, these features of the method are explained by using rigorous mathematical reasoning. Three derivative matching theoremsare proven which show that the observed numerical behavior is generic to the method. PMID:22500492

  5. Single-level optimization of a hybrid SOFC-GT power plant

    NASA Astrophysics Data System (ADS)

    Calise, F.; Dentice d'Accadia, M.; Vanoli, L.; von Spakovsky, M. R.

    The detailed synthesis/design optimization of a hybrid solid oxide fuel cell-gas turbine (SOFC-GT) power plant is presented in this paper. In the first part of the paper, the bulk-flow model used to simulate the plant is discussed. The performance of the centrifugal compressors and radial turbine is determined using maps, properly scaled in order to match the values required for mass flow rate and pressure ratio. Compact heat exchangers are simulated using Colburn and friction factor correlations. For the SOFC, the cell voltage versus current density curves (i.e. polarization curves) are generated on the basis of the Nernst potential and overvoltages. Validation of the SOFC polarization curves is accomplished with data available from Siemens Westinghouse. Both the steam-methane pre-reforming and internal reforming processes are modeled assuming the water-gas shift reaction to be equilibrium-controlled and the demethanization reactions to be kinetically controlled. Finally, a thermoeconomic model is developed by introducing capital cost functions for each plant component. The whole plant is first simulated for a fixed configuration. Then, a synthesis/design optimization of the plant is carried out using a traditional single-level approach. The results of the optimization are presented and discussed.

  6. SLS Scale Model Acoustic Test Liftoff Results and Comparisons

    NASA Technical Reports Server (NTRS)

    Houston, Janice; Counter, Douglas; Giacomoni, Clothilde

    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 design phase 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.

  7. Action of an electromagnetic pulse on a plasma with a high level of ion-acoustic turbulence. Field diffusion and subdiffusion

    SciTech Connect

    Ovchinnikov, K. N.; Uryupin, S. A.

    2013-09-15

    Specific features of the interaction of a relatively weak electromagnetic pulse with a nonisothermal current-carrying plasma in which the electron drift velocity is much higher than the ion-acoustic velocity, but lower than the electron thermal velocity, are studied. If the state of the plasma with ion-acoustic turbulence does not change during the pulse action, the field penetrates into the plasma in the ordinary diffusion regime, but the diffusion coefficient in this case is inversely proportional to the anomalous conductivity. If, during the pulse action, the particle temperatures and the current-driving field change due to turbulent heating, the field penetrates into the plasma in the subdiffusion regime. It is shown how the presence of subdiffusion can be detected by measuring the reflected field.

  8. Sub-100 fs pulses at watt-level powers from a dissipative-soliton fiber laser

    PubMed Central

    Kieu, K.; Renninger, W. H.; Chong, A.; Wise, F. W.

    2011-01-01

    We report a mode-locked fiber laser that exploits dissipative-soliton pulse shaping along with cladding pumping for high average power. The laser generates 31 nJ chirped pulses at 70 MHz repetition rate, for an average power of 2.2 W. After dechirping outside the laser, 80 fs pulses, with 200 kW peak power, are obtained. PMID:19252562

  9. Early Experiences with Node-Level Power Capping on the Cray XC40 Platform

    SciTech Connect

    Pedretti, Kevin; Olivier, Stephen Lecler; Ferreira, Kurt Brian; Shipman, Galen; Shu, Wei

    2015-10-01

    Power consumption of extreme-scale supercomputers has become a key performance bottleneck. Yet current practices do not leverage power management opportunities, instead running at ''maximum power''. This is not sustainable. Future systems will need to manage power as a critical resource, directing where it has greatest benefit. Power capping is one mechanism for managing power budgets, however its behavior is not well understood. This paper presents an empirical evaluation of several key HPC workloads running under a power cap on a Cray XC40 system, and provides a comparison of this technique with p-state control, demonstrating the performance differences of each. These results show: 1. Maximum performance requires ensuring the cap is not reached; 2. Performance slowdown under a cap can be attributed to cascading delays which result in unsynchronized performance variability across nodes; and, 3. Due to lag in reaction time, considerable time is spent operating above the set cap. This work provides a timely and much needed comparison of HPC application performance under a power cap and attempts to enable users and system administrators to understand how to best optimize application performance on power-constrained HPC systems.

  10. a High-Level Technique for Estimation and Optimization of Leakage Power for Full Adder

    NASA Astrophysics Data System (ADS)

    Shrivas, Jayram; Akashe, Shyam; Tiwari, Nitesh

    2013-06-01

    Optimization of power is a very important issue in low-voltage and low-power application. In this paper, we have proposed power gating technique to reduce leakage current and leakage power of one-bit full adder. In this power gating technique, we use two sleep transistors i.e., PMOS and NMOS. PMOS sleep transistor is inserted between power supply and pull up network. And NMOS sleep transistor is inserted between pull down network and ground terminal. These sleep transistors (PMOS and NMOS) are turned on when the circuit is working in active mode. And sleep transistors (PMOS and NMOS) are turned off when circuit is working in standby mode. We have simulated one-bit full adder and compared with the power gating technique using cadence virtuoso tool in 45 nm technology at 0.7 V at 27°C. By applying this technique, we have reduced leakage current from 2.935 pA to 1.905 pA and leakage power from 25.04μw to 9.233μw. By using this technique, we have reduced leakage power up to 63.12%.

  11. Lake Erie water level study. Appendix E. Power. Annex D. Computer programs. Final report

    SciTech Connect

    Not Available

    1981-07-01

    This Annex is part of Appendix E - Power. Appendix E contains the economic evaluation of Lake Erie regulation plans in terms of their effects on the generation of hydroelectric power on the connecting channels of the Great Lakes and on the St. Lawrence River. It also contains a description of the methodology that was developed for the purpose of carrying out this evaluation. The purpose of Annex D is to document the computer programs that were used for the determination of power output at each of the power plants. The documentation also provides sufficient user instructions to permit the economic evaluation results to be readily reproducible.

  12. [The effects of acoustic overstimulation].

    PubMed

    Häusler, R

    2004-01-01

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

  13. Experimental and simulation investigations of acoustic cavitation in megasonic cleaning

    NASA Astrophysics Data System (ADS)

    Muralidharan, Krishna; Keswani, Manish; Shende, Hrishikesh; Deymier, Pierre; Raghavan, Srini; Eschbach, Florence; Sengupta, Archita

    2007-03-01

    Extreme ultra-violet (EUV) lithography has become the technique of choice to print the ever-shrinking nanoscale features on the silicon wafer. For successful transfer of patterns on to the wafer, the EUV photomask cannot contain defects greater than 30 nm. Megasonic cleaning is a very successful cleaning technique for removal of particles on photomasks, but also causes a relatively high amount of damage to the fragile EUV photomasks thin film structures. Though it is believed that acoustic cavitation is the primary phenomenon responsible for cleaning as well as pattern damage, a fundamental picture of the acoustic cavitation mechanisms in play during megasonic cleaning has not yet clearly emerged. In this study, we characterize the role of acoustic cavitation in megasonic cleaning by examining the effects of acoustic power densities, cleaning solution properties, and dissolved gas content on cavitation via experiments and molecular dynamics (MD) simulations. MD is an atomistic computation technique capable of modeling atomic-level and nanoscale processes accurately making it well suited to study the effect of cavitation on nano-sized particles and patterns.

  14. MRI acoustic noise: sound pressure and frequency analysis.

    PubMed

    Counter, S A; Olofsson, A; Grahn, H F; Borg, E

    1997-01-01

    The large gradient coils used in MRI generate, simultaneously with the pulsed radiofrequency (RF) wave, acoustic noise of high intensity that has raised concern regarding hearing safety. The sound pressure levels (SPLs) and power spectra of MRI acoustic noise were measured at the position of the human head in the isocenter of five MRI systems and with 10 different pulse sequences used in clinical MR scanning. Each protocol, including magnetization-prepared rapid gradient echo (MP-RAGE; 113 dB SPL linear), fast gradient echo turbo (114 dB SPL linear), and spin echo T1/2 mm (117 dB SPL linear), was found to have the high SPLs, rapid pulse rates, amplitude-modulated pulse envelopes, and multipeaked spectra. Since thickness and SPL were inversely related, the T1-weighted images generated more intense acoustic noise than the proton-dense T2-weighted measures. The unfiltered linear peak values provided more accurate measurements of the SPL and spectral content of the MRI acoustic noise than the commonly used dB A-weighted scale, which filters out the predominant low frequency components. Fourier analysis revealed predominantly low frequency energy peaks ranging from .05 to approximately 1 kHz, with a steep high frequency cutoff for each pulse sequence. Ear protectors of known attenuation ratings are recommended for all patients during MRI testing.

  15. Influence of energy-transfer-upconversion on threshold pump power in quasi-three-level solid-state lasers.

    PubMed

    Kim, J W; Mackenzie, J I; Clarkson, W A

    2009-07-06

    A simple analytical expression for threshold pump power in an end-pumped quasi-three-level solid-state laser, which takes into account the influence of energy-transfer-upconversion (ETU), is derived. This expression indicates that threshold pump power can be increased dramatically by ETU, especially in low gain lasers and lasers with pronounced three-level character due to the need for high excitation densities in the upper manifold to reach threshold. The analysis has been applied to an Er:YAG laser operating at 1645 nm in-band pumped by an Er,Yb fiber laser at 1532 nm. Predicted values for threshold pump power as a function of erbium doping concentration are in very good agreement with measured values. The results indicate that very low erbium doping levels (approximately 0.25 at.% or less) are required to avoid degradation in performance due to ETU even under continuous-wave lasing conditions in Er:YAG.

  16. Design and performance of duct acoustic treatment

    NASA Technical Reports Server (NTRS)

    Motsinger, R. E.; Kraft, R. E.

    1991-01-01

    The procedure for designing acoustic treatment panels used to line the walls of aircraft engine ducts and for estimating the resulting suppression of turbofan engine duct noise is discussed. This procedure is intended to be used for estimating noise suppression of existing designs or for designing new acoustic treatment panels and duct configurations to achieve desired suppression levels.

  17. Applications of acoustics in insect pest management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acoustic technology has been applied for many years in studies of insect communication and in the monitoring of calling-insect population levels, geographic distributions, and diversity, as well as in the detection of cryptic insects in soil, wood, container crops, and stored products. Acoustic devi...

  18. 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.

  19. 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.

  20. The Effects of a Maximal Power Training Cycle on the Strength, Maximum Power, Vertical Jump Height and Acceleration of High-Level 400-Meter Hurdlers

    PubMed Central

    Balsalobre-Fernández, Carlos; Tejero-González, Carlos Mª; del Campo-Vecino, Juan; Alonso-Curiel, Dionisio

    2013-01-01

    The aim of this study was to determine the effects of a power training cycle on maximum strength, maximum power, vertical jump height and acceleration in seven high-level 400-meter hurdlers subjected to a specific training program twice a week for 10 weeks. Each training session consisted of five sets of eight jump-squats with the load at which each athlete produced his maximum power. The repetition maximum in the half squat position (RM), maximum power in the jump-squat (W), a squat jump (SJ), countermovement jump (CSJ), and a 30-meter sprint from a standing position were measured before and after the training program using an accelerometer, an infra-red platform and photo-cells. The results indicated the following statistically significant improvements: a 7.9% increase in RM (Z=−2.03, p=0.021, δc=0.39), a 2.3% improvement in SJ (Z=−1.69, p=0.045, δc=0.29), a 1.43% decrease in the 30-meter sprint (Z=−1.70, p=0.044, δc=0.12), and, where maximum power was produced, a change in the RM percentage from 56 to 62% (Z=−1.75, p=0.039, δc=0.54). As such, it can be concluded that strength training with a maximum power load is an effective means of increasing strength and acceleration in high-level hurdlers. PMID:23717361

  1. Coherent Power Analysis in Multi-Level Studies Using Design Parameters from Surveys

    ERIC Educational Resources Information Center

    Rhoads, Christopher

    2016-01-01

    Current practice for conducting power analyses in hierarchical trials using survey based ICC and effect size estimates may be misestimating power because ICCs are not being adjusted to account for treatment effect heterogeneity. Results presented in Table 1 show that the necessary adjustments can be quite large or quite small. Furthermore, power…

  2. Prototype acoustic resonance spectroscopy monitor

    SciTech Connect

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

    1996-03-01

    This report reports on work performed for the International Atomic Energy Agency (IAEA) through the Program Office for Technical Assistance (POTAS). In this work, we investigate possible applications of nondestructive acoustics measurements to facilitate IAEA safeguards at bulk processing facilities. Two different acoustic techniques for verifying the internal structure of a processing tank were investigated. During this effort we also examined two acoustic techniques for assessing the fill level within a processing tank. The fill-level measurements could be made highly portable and have an added safeguards advantage that they can also detect stratification of fill material. This later application may be particularly useful in confirming the absence of stratification in plutonium processing tanks before accountability samples are withdrawn.

  3. Acoustic pressure-vector sensor array

    NASA Astrophysics Data System (ADS)

    Huang, Dehua; Elswick, Roy C.; McEachern, James F.

    2004-05-01

    Pressure-vector sensors measure both scalar and vector components of the acoustic field. December 2003 measurements at the NUWC Seneca Lake test facility verify previous observations that acoustic ambient noise spectrum levels measured by acoustic intensity sensors are reduced relative to either acoustic pressure or acoustic vector sensor spectrum levels. The Seneca measurements indicate a reduction by as much as 15 dB at the upper measurement frequency of 2500 Hz. A nonlinear array synthesis theory for pressure-vector sensors will be introduced that allows smaller apertures to achieve narrow beams. The significantly reduced ambient noise of individual pressure-vector elements observed in the ocean by others, and now at Seneca Lake, should allow a nonlinearly combined array to detect significantly lower levels than has been observed in previous multiplicative processing of pressure sensors alone. Nonlinear array synthesis of pressure-vector sensors differs from conventional super-directive algorithms that linearly combine pressure elements with positive and negative weights, thereby reducing the sensitivity of conventional super-directive arrays. The much smaller aperture of acoustic pressure-vector sensor arrays will be attractive for acoustic systems on underwater vehicles, as well as for other applications that require narrow beam acoustic receivers. [The authors gratefully acknowledge the support of ONR and NUWC.

  4. Acoustic characterization of two megasonic devices for photomask cleaning

    NASA Astrophysics Data System (ADS)

    Zanelli, Claudio; Giridhar, Dushyanth; Keswani, Manish; Okada, Nagaya; Hsu, Jyhwei; Yam, Petrie

    2016-10-01

    Wet photomask cleaning relies on megasonic agitation to enhance the process, but there are many challenges to reliably maximize particle removal efficiency (PRE) and minimize damage. With the shift to pellicle-free EUV masks, photomask processes are more vulnerable to contamination, increasing the urgency to improve the cleaning process. This difficulty is largely due to the unavailability of appropriate measurement of the acoustic field. Typically all that is known about the acoustic output is the driving frequency and the electric power delivered to a transducer, both global parameters that tell little about the field distribution over the substrate, the actual amplitude of the sound at the substrate, or the levels of cavitation (stable and transient) present at the substrate.

  5. Fan Acoustic Issues in the NASA Space Flight Experience

    NASA Technical Reports Server (NTRS)

    Allen, Christopher S.; Goodman, Jerry

    2008-01-01

    Emphasis needs to be placed on choosing quiet fans compatible with systems design and specifications that control spec levels: a) Sound power; b) Choose quiet fan or plan to quiet it, early in program; c) Plan early verification that fan source allocations are met. Airborne noise: a) System design should function/play together with fans used (flow passages, restrictions, bends, expansions & contractions, and acoustics) vs. fan speed understood (nominal, worst case, & unplanned variances); b) Fan inlets treated, as required; c) Fan Outlets treated, as required; d) Ducted system inlets are outlets designed for acoustic compliance compatibility & designed so some late required modifications can be made without significant impacts. Structure Borne Noise: a) Structure borne noise dealt with as part of fan package or installation; b) Duct attachments and lines isolated. Case Radiated Noise: - Treatment added as much as possible to fan package (see example).

  6. Sonification of acoustic emission data

    NASA Astrophysics Data System (ADS)

    Raith, Manuel; Große, Christian

    2014-05-01

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

  7. System-level considerations for the front-end readout ASIC in the CBM experiment from the power supply perspective

    NASA Astrophysics Data System (ADS)

    Kasinski, K.; Koczon, P.; Ayet, S.; Löchner, S.; Schmidt, C. J.

    2017-03-01

    New fixed target experiments using high intensity beams with energy up to 10 AGeV from the SIS100 synchrotron presently being constructed at FAIR/GSI are under preparation. Most of the readout electronics and power supplies are expected to be exposed to a very high flux of nuclear reaction products and have to be radiation tolerant up to 3 MRad (TID) and sustain up to 1014/cm2 of 1 MeV neutron equivalent in their life time. Moreover, the mostly minimum ionising particles under investigation leave very little signal in the sensors. Therefore very low noise level amplitude measurements are required by the front-end electronics for effective tracking. Sensor and interconnecting micro-cable capacitance and series resistance in conjunction with intrinsic noise of the charge sensitive amplifier are dominant noise sources in the system. However, the single-ended architecture of the amplifiers employed for the charge processing channels implies a potential problem with noise contributions from power supply sources. Strict system-level constraints leave very little freedom in selecting a power supply structure optimal with respect to: power efficiency, cooling capabilities and power density on modules, but also noise injection to the front-end via the power supply lines. Design of the power supply and distribution system of the Silicon Tracking System in the CBM experiment together with details on the front-end ASICs (STS -XYTER2) and measurement results of power supply and conditioning electronics (selected DC/DC converter and LDO regulators) are presented.

  8. Writing magnetic patterns with surface acoustic waves

    SciTech Connect

    Li, Weiyang; Buford, Benjamin; Jander, Albrecht; Dhagat, Pallavi

    2014-05-07

    A novel patterning technique that creates magnetization patterns in a continuous magnetostrictive film with surface acoustic waves is demonstrated. Patterns of 10 μm wide stripes of alternating magnetization and a 3 μm dot of reversed magnetization are written using standing and focusing acoustic waves, respectively. The magnetization pattern is size-tunable, erasable, and rewritable by changing the magnetic field and acoustic power. This versatility, along with its solid-state implementation (no moving parts) and electronic control, renders it as a promising technique for application in magnetic recording, magnonic signal processing, magnetic particle manipulation, and spatial magneto-optical modulation.

  9. 75 FR 24755 - DTE ENERGY; Enrico Fermi Atomic Power Plant Unit 1; Exemption From Certain Low-Level Waste...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-05

    .... DTE is in the process of decommissioning Fermi-1 and radioactive waste shipments from the site are... offsite low-level radioactive waste disposal sites. Experience at other decommissioning nuclear power facilities has shown that, due primarily to the volume of radioactive waste; licensees have encountered...

  10. Acoustic Characteristics of a Model Isolated Tiltrotor in DNW

    NASA Technical Reports Server (NTRS)

    Booth, Earl R., Jr.; McCluer, Megan; Tadghighi, Hormoz

    1999-01-01

    An aeroacoustic wind tunnel test was conducted using a scaled isolated tiltrotor model. Acoustic data were acquired using an in-flow microphone wing traversed beneath the model to map the directivity of the near-field acoustic radiation of the rotor for a parametric variation of rotor angle-of-attack, tunnel speed, and rotor thrust. Acoustic metric data were examined to show trends of impulsive noise for the parametric variations. BVISPL maximum noise levels were found to increase with alpha for constant mu and C(sub T), although the maximum BVI levels were found at much higher a than for a typical helicopter. BVISPL levels were found to increase with mu for constant alpha and C(sub T. BVISPL was found to decrease with increasing CT for constant a and m, although BVISPL increased with thrust for a constant wake geometry. Metric data were also scaled for M(sub up) to evaluate how well simple power law scaling could be used to correct metric data for M(sub up) effects.

  11. Acoustic characteristics of a large-scale augmentor wing model at forward speed

    NASA Technical Reports Server (NTRS)

    Falarski, M. D.; Koenig, D. G.

    1973-01-01

    The augmentor wing concept is being studied as one means of attaining short takeoff and landing (STOL) performance in turbofan powered aircraft. Because of the stringent noise requirements for STOL operation, the acoustics of the augmentor wing are undergoing extensive research. The results of a wind tunnel investigation of a large-scale swept augmentor model at forward speed are presented. The augmentor was not acoustically treated, although the compressor supplying the high pressure primary air was treated to allow the measurement of only the augmentor noise. Installing the augmentor flap and shroud on the slot primary nozzle caused the acoustic dependence on jet velocity to change from eighth power to sixth power. Deflecting the augmentor at constant power increased the perceived noise level in the forward quadrant. The effect of airspeed was small. A small aft shift in perceived noise directivity was experienced with no significant change in sound power. Sealing the lower augmentor slot at a flap deflection of 70 deg reduced the perceived noise level in the aft quadrant. The seal prevented noise from propagating through the slot.

  12. International Space Station Acoustics - A Status Report

    NASA Technical Reports Server (NTRS)

    Allen, Christopher S.

    2015-01-01

    It is important to control acoustic noise aboard the International Space Station (ISS) to provide a satisfactory environment for voice communications, crew productivity, alarm audibility, and restful sleep, and to minimize the risk for temporary and permanent hearing loss. Acoustic monitoring is an important part of the noise control process on ISS, providing critical data for trend analysis, noise exposure analysis, validation of acoustic analyses and predictions, and to provide strong evidence for ensuring crew health and safety, thus allowing Flight Certification. To this purpose, sound level meter (SLM) measurements and acoustic noise dosimetry are routinely performed. And since the primary noise sources on ISS include the environmental control and life support system (fans and airflow) and active thermal control system (pumps and water flow), acoustic monitoring will reveal changes in hardware noise emissions that may indicate system degradation or performance issues. This paper provides the current acoustic levels in the ISS modules and sleep stations and is an update to the status presented in 2011. Since this last status report, many payloads (science experiment hardware) have been added and a significant number of quiet ventilation fans have replaced noisier fans in the Russian Segment. Also, noise mitigation efforts are planned to reduce the noise levels of the T2 treadmill and levels in Node 3, in general. As a result, the acoustic levels on the ISS continue to improve.

  13. Compensating for ear-canal acoustics when measuring otoacoustic emissions.

    PubMed

    Charaziak, Karolina K; Shera, Christopher A

    2017-01-01

    Otoacoustic emissions (OAEs) provide an acoustic fingerprint of the inner ear, and changes in this fingerprint may indicate changes in cochlear function arising from efferent modulation, aging, noise trauma, and/or exposure to harmful agents. However, the reproducibility and diagnostic power of OAE measurements is compromised by the variable acoustics of the ear canal, in particular, by multiple reflections and the emergence of standing waves at relevant frequencies. Even when stimulus levels are controlled using methods that circumvent standing-wave problems (e.g., forward-pressure-level calibration), distortion-product otoacoustic emission (DPOAE) levels vary with probe location by 10-15 dB near half-wave resonant frequencies. The method presented here estimates the initial outgoing OAE pressure wave at the eardrum from measurements of the conventional OAE, allowing one to separate the emitted OAE from the many reflections trapped in the ear canal. The emitted pressure level (EPL) represents the OAE level that would be recorded were the ear canal replaced by an infinite tube with no reflections. When DPOAEs are expressed using EPL, their variation with probe location decreases to the test-retest repeatability of measurements obtained at similar probe positions. EPL provides a powerful way to reduce the variability of OAE measurements and improve their ability to detect cochlear changes.

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

    PubMed

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

    2016-03-01

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

  15. Cylindrical acoustic levitator/concentrator

    DOEpatents

    Kaduchak, Gregory; Sinha, Dipen N.

    2002-01-01

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

  16. Acoustic behaviors of unsaturated soils

    NASA Astrophysics Data System (ADS)

    Lu, Z.

    2011-12-01

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

  17. Effect of Voltage Level on Power System Design for Solar Electric Propulsion Missions

    NASA Technical Reports Server (NTRS)

    Kerslake, Thomas W.

    2003-01-01

    This paper presents study results quantifying the benefits of higher voltage, electric power system designs for a typical solar electric propulsion spacecraft Earth orbiting mission. A conceptual power system architecture was defined and design points were generated for system voltages of 28-V, 50-V, 120-V, and 300-V using state-of-the-art or advanced technologies. A 300-V 'direct-drive' architecture was also analyzed to assess the benefits of directly powering the electric thruster from the photovoltaic array without up-conversion. Fortran and spreadsheet computational models were exercised to predict the performance and size power system components to meet spacecraft mission requirements. Pertinent space environments, such as electron and proton radiation, were calculated along the spiral trajectory. In addition, a simplified electron current collection model was developed to estimate photovoltaic array losses for the orbital plasma environment and that created by the thruster plume. The secondary benefits of power system mass savings for spacecraft propulsion and attitude control systems were also quantified. Results indicate that considerable spacecraft wet mass savings were achieved by the 300-V and 300-V direct-drive architectures.

  18. Wearable Sensor System Powered by a Biofuel Cell for Detection of Lactate Levels in Sweat

    PubMed Central

    Garcia, S. O.; Ulyanova, Y. V.; Figueroa-Teran, R.; Bhatt, K. H.; Singhal, S.; Atanassov, P.

    2016-01-01

    An NAD+-dependent enzymatic sensor with biofuel cell power source system for non-invasive monitoring of lactate in sweat was designed, developed, and tested. The sensor component, based on lactate dehydrogenase, showed linear current response with increasing lactate concentrations with limits of detection from 5 to 100 mM lactate and sensitivity of 0.2 µA.mM−1 in the presence of target analyte. In addition to the sensor patch a power source was also designed, developed and tested. The power source was a biofuel cell designed to oxidize glucose via glucose oxidase. The biofuel cell showed excellent performance, achieving over 80 mA at 0.4 V (16 mW) in a footprint of 3.5 × 3.5 × 0.7 cm. Furthermore, in order to couple the sensor to the power source, system electronic components were designed and fabricated. These consisted of an energy harvester (EH) and a micropotentiostat (MP). The EH was employed for harvesting power provided by the biofuel cell as well as up-converting the voltage to 3.0 V needed for the operation of the MP. The sensor was attached to MP for chronoamperometric detection of lactate. The Sensor Patch System was demonstrated under laboratory conditions. PMID:27375962

  19. Recovering Power in Association Mapping Panels with Variable Levels of Linkage Disequilibrium

    PubMed Central

    Rincent, Renaud; Moreau, Laurence; Monod, Hervé; Kuhn, Estelle; Melchinger, Albrecht E.; Malvar, Rosa A.; Moreno-Gonzalez, Jesus; Nicolas, Stéphane; Madur, Delphine; Combes, Valérie; Dumas, Fabrice; Altmann, Thomas; Brunel, Dominique; Ouzunova, Milena; Flament, Pascal; Dubreuil, Pierre; Charcosset, Alain; Mary-Huard, Tristan

    2014-01-01

    Association mapping has permitted the discovery of major QTL in many species. It can be applied to existing populations and, as a consequence, it is generally necessary to take into account structure and relatedness among individuals in the statistical model to control false positives. We analytically studied power in association studies by computing noncentrality parameter of the tests and its relationship with parameters characterizing diversity (genetic differentiation between groups and allele frequencies) and kinship between individuals. Investigation of three different maize diversity panels genotyped with the 50k SNPs array highlighted contrasted average power among panels and revealed gaps of power of classical mixed models in regions with high linkage disequilibrium (LD). These gaps could be related to the fact that markers are used for both testing association and estimating relatedness. We thus considered two alternative approaches to estimating the kinship matrix to recover power in regions of high LD. In the first one, we estimated the kinship with all the markers that are not located on the same chromosome than the tested SNP. In the second one, correlation between markers was taken into account to weight the contribution of each marker to the kinship. Simulations revealed that these two approaches were efficient to control false positives and were more powerful than classical models. PMID:24532779

  20. Wearable Sensor System Powered by a Biofuel Cell for Detection of Lactate Levels in Sweat.

    PubMed

    Garcia, S O; Ulyanova, Y V; Figueroa-Teran, R; Bhatt, K H; Singhal, S; Atanassov, P

    An NAD(+)-dependent enzymatic sensor with biofuel cell power source system for non-invasive monitoring of lactate in sweat was designed, developed, and tested. The sensor component, based on lactate dehydrogenase, showed linear current response with increasing lactate concentrations with limits of detection from 5 to 100 mM lactate and sensitivity of 0.2 µA.mM(-1) in the presence of target analyte. In addition to the sensor patch a power source was also designed, developed and tested. The power source was a biofuel cell designed to oxidize glucose via glucose oxidase. The biofuel cell showed excellent performance, achieving over 80 mA at 0.4 V (16 mW) in a footprint of 3.5 × 3.5 × 0.7 cm. Furthermore, in order to couple the sensor to the power source, system electronic components were designed and fabricated. These consisted of an energy harvester (EH) and a micropotentiostat (MP). The EH was employed for harvesting power provided by the biofuel cell as well as up-converting the voltage to 3.0 V needed for the operation of the MP. The sensor was attached to MP for chronoamperometric detection of lactate. The Sensor Patch System was demonstrated under laboratory conditions.

  1. Acoustical Modifications for the Classroom.

    ERIC Educational Resources Information Center

    Crandell, Carl C.; Smaldino, Joseph J.

    1999-01-01

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

  2. Acoustic Climb to Cruise Test

    NASA Technical Reports Server (NTRS)

    1991-01-01

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

  3. 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.

  4. Aero-acoustic features of internal and external chamfered Hartmann whistles: A comparative study

    NASA Astrophysics Data System (ADS)

    Narayanan, S.; Srinivasan, K.; Sundararajan, T.

    2014-02-01

    The efficient way of chamfering at the mouth of Hartmann whistles in generating higher acoustic emission levels are experimentally demonstrated in this paper. The relevant parameters of the present work comprise internal and external-chamfer angles (15°, 30°), cavity-length, nozzle-to-cavity-distance and jet pressure ratios. The frequency and amplitude characteristics of internal and external, chamfered-Hartmann whistles are compared in detail to ascertain the role of chamfering in enhancing acoustic radiations. The high frequencies possessed by the internal chamfered whistles as compared to the external ones indicate that it amplifies the resonance. It is observed that the internal chamfered whistles exhibit higher directivity than the external chamfered ones. Further, it is noticed that the acoustic-power and efficiency are also higher for the internal chamfered whistles. The shadowgraph sequences reveal the variance in flow-shock oscillations as well as the spill-over features at the mouth of internal and external, chamfered cavities. The presence of large mass flow as well as its subsequent increase of spill-over as a result of enlarged mouth in internal chamfered whistles, leads to the generation of high intensity acoustic radiation than the external chamfered ones. Thus, the internal chamfer proves to be the best passive control device for augmented sound pressure levels and acoustic efficiencies in resonance cavities.

  5. Integrated Solar Power Converters: Wafer-Level Sub-Module Integrated DC/DC Converter

    SciTech Connect

    2012-02-09

    Solar ADEPT Project: CU-Boulder is developing advanced power conversion components that can be integrated into individual solar panels to improve energy yields. The solar energy that is absorbed and collected by a solar panel is converted into useable energy for the grid through an electronic component called an inverter. Many large, conventional solar energy systems use one, central inverter to convert energy. CU-Boulder is integrating smaller, microinverters into individual solar panels to improve the efficiency of energy collection. The University’s microinverters rely on electrical components that direct energy at high speeds and ensure that minimal energy is lost during the conversion process—improving the overall efficiency of the power conversion process. CU-Boulder is designing its power conversion devices for use on any type of solar panel.

  6. 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.

  7. What Is an Acoustic Neuroma

    MedlinePlus

    ... ANAUSA.org Connect with us! What is an Acoustic Neuroma? Each heading slides to reveal information. Important ... Acoustic Neuroma Important Points To Know About an Acoustic Neuroma An acoustic neuroma, also called a vestibular ...

  8. Contribution of power and desalination plants to the levels of volatile liquid hydrocarbons in the nearby coastal areas of Kuwait

    SciTech Connect

    Saeed, T.; Khordagui, H.; Al-Hashash, H.

    1999-07-01

    The levels and distribution of volatile liquid hydrocarbons (VLHs) were determined in Kuwait`s coastal areas in the vicinity of outlets of power and desalination plants. About 230 samples were collected from the selected sampling locations over the 4 seasons. The VLHs in the samples were analyzed using Grob`s closed-loop stripping technique and GC with FID and confirmed by GC/MS. The results showed that significant levels of VLHs were present. The levels ranged from 307 to 6,500 ng/L and from 2,880 to 7,811 ng/L in Kuwait Bay and Sulaibekhat Bay, respectively. The annual average for VLHs near Al-Zor power plant ranged from 465 to 4,665 ng/L. Benzenoids formed the bulk (about 80%) of the VLHs present. Comparison with the levels in the outlets indicated that Doha West power plant contributed much higher levels of VLHs to the coastal areas than Al-Zor plant.

  9. Solid Rocket Motor Acoustic Testing

    SciTech Connect

    Rogers, J.D.

    1999-03-31

    Acoustic data are often required for the determination of launch and powered flight loads for rocket systems and payloads. Such data are usually acquired during test firings of the solid rocket motors. In the current work, these data were obtained for two tests at a remote test facility where we were visitors. This paper describes the data acquisition and the requirements for working at a remote site, interfacing with the test hosts.

  10. Megawatt-level peak-power from a passively Q-switched hybrid fiber-bulk amplifier and its applications

    NASA Astrophysics Data System (ADS)

    Reiser, Axel; Bdzoch, Juraj; Höfer, Sven; Scholz-Riecke, Sina; Seitz, Daniel; Kugler, Nicolas; Genter, Peter

    2016-03-01

    A novel laser system with optical parameters that fill the gap between Q-switched and modelocked lasers has been developed. It consists of a high gain hybrid fiber-bulk amplifier seeded by a low power SESAM Q-switched oscillator. The mW level output power of the seed oscillator is preamplified by a single mode fiber which is limited by SRS effects. The final amplification stage is realized by a longitudinal pumped Nd:YVO4 crystal in a double pass setup. This MOPA configuration delivers sub-300ps pulses at repetition rates up to 1 MHz with an output power exceeding 60W. Nonlinear frequency conversion to 532nm and 355nm is achieved with efficiencies of >75% and >45%, respectively. Due to the high peak power, high repetition rate and high beam quality of this system, applications formerly only addressable at lower pulse repetition frequencies or with complex modelocked laser systems are now possible with high speed and lower cost of ownership. Application results that take benefit from these new laser parameters will be shown. Furthermore, the reduction of the pulse duration to sub-100ps and power scaling to output powers <100W by the use of the Innoslab concept are being presented.

  11. My 65 years in acoustics

    NASA Astrophysics Data System (ADS)

    Beranek, Leo L.

    2004-05-01

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

  12. My 65 years in acoustics

    NASA Astrophysics Data System (ADS)

    Beranek, Leo L.

    2001-05-01

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

  13. Subwavelength slit acoustic metamaterial barrier

    NASA Astrophysics Data System (ADS)

    Rubio, Constanza; Candelas, Pilar; Belmar, Francisco; Gomez-Lozano, Vicente; Uris, Antonio

    2015-10-01

    Reduction of noise in the transmission path is a very important environmental problem. The standard method to reduce this noise level is the use of acoustic barriers. In this paper, an acoustic metamaterial based on sound transmission through subwavelength slits, is tailored to be used as an acoustic barrier. This system consists of two rows of periodic repetition of vertical rigid pickets separated by a slit of subwavelength width, embedded in air. Here, both the experimental and the numerical analyses are presented. These analyses have facilitated the identification of the parameters that affect the insertion loss performance. The results demonstrated that the proposed barrier can be tuned to mitigate a band noise in a mechanical plant for buildings where openings for air flow are required as well as industrial noise, without excessive barrier thickness.

  14. Conceptual architectural/acoustical design

    NASA Astrophysics Data System (ADS)

    Marshall, A. Harold

    2004-05-01

    The thinking which characterizes acoustics as a branch of physics and engineering has difficulty with the architectural design process-the process that generates a room concept in the imagination and experience of the architect. The architect has learned to ``sense'' the visual properties of a room as the design develops in the interaction between mind and media. Phrases such as ``wanting to be'' express the architectural intention but too often such intentions are dismissed as arbitrary; acoustics may then be about fixing the design with acoustical add-ons. Occasionally there is a true meeting of minds-a creative and receptive architect and an acoustician able to communicate at the level of the architectural intention. There is evidently an auditory dimension of wanting to be which is one with the visual. This paper explores the idea in several examples and concludes with suggestions for the training of acousticians.

  15. Wavelet preprocessing of acoustic signals

    NASA Astrophysics Data System (ADS)

    Huang, W. Y.; Solorzano, M. R.

    1991-12-01

    This paper describes results using the wavelet transform to preprocess acoustic broadband signals in a system that discriminates between different classes of acoustic bursts. This is motivated by the similarity between the proportional bandwidth filters provided by the wavelet transform and those found in biological hearing systems. The experiment involves comparing statistical pattern classifier effects of wavelet and FFT preprocessed acoustic signals. The data used was from the DARPA Phase 1 database, which consists of artificially generated signals with real ocean background. The results show that the wavelet transform did provide improved performance when classifying in a frame-by-frame basis. The DARPA Phase 1 database is well matched to proportional bandwidth filtering; i.e., signal classes that contain high frequencies do tend to have shorter duration in this database. It is also noted that the decreasing background levels at high frequencies compensate for the poor match of the wavelet transform for long duration (high frequency) signals.

  16. Drivers for the Value of Demand Response under Increased Levels of Wind and Solar Power; NREL (National Renewable Energy Laboratory)

    SciTech Connect

    Hale, Elaine

    2015-07-30

    Demand response may be a valuable flexible resource for low-carbon electric power grids. However, there are as many types of possible demand response as there are ways to use electricity, making demand response difficult to study at scale in realistic settings. This talk reviews our state of knowledge regarding the potential value of demand response in several example systems as a function of increasing levels of wind and solar power, sometimes drawing on the analogy between demand response and storage. Overall, we find demand response to be promising, but its potential value is very system dependent. Furthermore, demand response, like storage, can easily saturate ancillary service markets.

  17. International Space Station Acoustics - A Status Report

    NASA Technical Reports Server (NTRS)

    Allen, Christopher S.; Denham, Samuel A.

    2011-01-01

    It is important to control acoustic noise aboard the International Space Station (ISS) to provide a satisfactory environment for voice communications, crew productivity, and restful sleep, and to minimize the risk for temporary and permanent hearing loss. Acoustic monitoring is an important part of the noise control process on ISS, providing critical data for trend analysis, noise exposure analysis, validation of acoustic analysis and predictions, and to provide strong evidence for ensuring crew health and safety, thus allowing Flight Certification. To this purpose, sound level meter (SLM) measurements and acoustic noise dosimetry are routinely performed. And since the primary noise sources on ISS include the environmental control and life support system (fans and airflow) and active thermal control system (pumps and water flow), acoustic monitoring will indicate changes in hardware noise emissions that may indicate system degradation or performance issues. This paper provides the current acoustic levels in the ISS modules and sleep stations, and is an update to the status presented in 20031. Many new modules, and sleep stations have been added to the ISS since that time. In addition, noise mitigation efforts have reduced noise levels in some areas. As a result, the acoustic levels on the ISS have improved.

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

    NASA Astrophysics Data System (ADS)

    Schmidt, Henrik; Jensen, Finn B.

    2012-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Elayouch, A.; Addouche, M.; Farhat, M.; Amin, M.; Bağcı, H.; Khelif, A.

    2016-11-01

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

  20. Incorporating Cost in Power Analysis for Three-Level Cluster-Randomized Designs

    ERIC Educational Resources Information Center

    Konstantopoulos, Spyros

    2009-01-01

    In experimental designs with nested structures, entire groups (such as schools) are often assigned to treatment conditions. Key aspects of the design in these cluster-randomized experiments involve knowledge of the intraclass correlation structure, the effect size, and the sample sizes necessary to achieve adequate power to detect the treatment…

  1. The Power of the Test for Treatment Effects in Three-Level Block Randomized Designs

    ERIC Educational Resources Information Center

    Konstantopoulos, Spyros

    2008-01-01

    Experiments that involve nested structures may assign treatment conditions either to subgroups (such as classrooms) or individuals within subgroups (such as students). The design of such experiments requires knowledge of the intraclass correlation structure to compute the sample sizes necessary to achieve adequate power to detect the treatment…

  2. The Impact of Covariates on Statistical Power in Cluster Randomized Designs: Which Level Matters More?

    ERIC Educational Resources Information Center

    Konstantopoulos, Spyros

    2012-01-01

    Field experiments with nested structures are becoming increasingly common, especially designs that assign randomly entire clusters such as schools to a treatment and a control group. In such large-scale cluster randomized studies the challenge is to obtain sufficient power of the test of the treatment effect. The objective is to maximize power…

  3. Assessment of Spatial Variation of Ambient VOCs Levels at a Power Station in Kuwait.

    PubMed

    Ramadan, Ashraf

    2016-10-04

    IMPLICATIONS Assessment of Volatile Organic Compounds (VOCs) concentrations around a power plant in Kuwait during the peak season showed halogenated compounds to be the dominant group. The calculated indoor concentrations were lower than that reported in a residential area about 12 km away.

  4. Teachers, School Boards, and the Power of Money: How the Right Wins at the Local Level

    ERIC Educational Resources Information Center

    Schirmer, Eleni B.; Apple, Michael W.

    2016-01-01

    This article examines national conservative political advocacy groups' growing interest in local politics, and analyzes how they form alliances and gain political power. Following efforts to restrict collective bargaining for Wisconsin public employees, Kenosha school board members' attempts to legally protect teachers' rights provoked concern…

  5. Water Use in the US Electric Power Sector: Energy Systems Level Perspectives

    EPA Science Inventory

    This presentation reviews the water demands of long-range electricity scenarios. It addresses questions such as: What are the aggregate water requirements of the U.S. electric power sector? How could water requirements evolve under different long-range regional generation mixes? ...

  6. Reconfigurable, Bi-Directional Flexfet Level Shifter for Low-Power, Rad-Hard Integration

    NASA Technical Reports Server (NTRS)

    DeGregorio, Kelly; Wilson, Dale G.

    2009-01-01

    Two prototype Reconfigurable, Bi-directional Flexfet Level Shifters (ReBiLS) have been developed, where one version is a stand-alone component designed to interface between external low voltage and high voltage, and the other version is an embedded integrated circuit (IC) for interface between internal low-voltage logic and external high-voltage components. Targeting stand-alone and embedded circuits separately allows optimization for these distinct applications. Both ReBiLS designs use the commercially available 180-nm Flex fet Independently Double-Gated (IDG) SOI CMOS (silicon on insulator, complementary metal oxide semiconductor) technology. Embedded ReBiLS circuits were integrated with a Reed-Solomon (RS) encoder using CMOS Ultra-Low-Power Radiation Tolerant (CULPRiT) double-gated digital logic circuits. The scope of the project includes: creation of a new high-voltage process, development of ReBiLS circuit designs, and adjustment of the designs to maximize performance through simulation, layout, and manufacture of prototypes. The primary technical objectives were to develop a high-voltage, thick oxide option for the 180-nm Flexfet process, and to develop a stand-alone ReBiLS IC with two 8-channel I/O busses, 1.8 2.5 I/O on the low-voltage pins, 5.0-V-tolerant input and 3.3-V output I/O on the high-voltage pins, and 100-MHz minimum operation with 10-pF external loads. Another objective was to develop an embedded, rad-hard ReBiLS I/O cell with 0.5-V low-voltage operation for interface with core logic, 5.0-V-tolerant input and 3.3-V output I/O pins, and 100-MHz minimum operation with 10- pF external loads. A third objective was to develop a 0.5- V Reed-Solomon Encoder with embedded ReBilS I/O: Transfer the existing CULPRiT RS encoder from a 0.35-micron bulk-CMOS process to the ASI 180-nm Flexfet, rad-hard SOI Process. 0.5-V low-voltage core logic. 5.0-V-tolerant input and 3.3-V output I/O pins. 100-MHz minimum operation with 10- pF external loads. The stand

  7. 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.

  8. 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 ...

  9. NPL closes acoustics department

    NASA Astrophysics Data System (ADS)

    Extance, Andy

    2016-11-01

    The UK's National Physical Laboratory (NPL) has withdrawn funding for its acoustics, polymer and thermoelectrics groups, triggering concern among airborne acoustics specialists that the move could undermine the country's noise-management policies.

  10. Identifying the 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 ...

  11. Fiber based photonic-crystal acoustic sensor

    NASA Astrophysics Data System (ADS)

    Kilic, Onur

    -crystal reflector embedded in a compliant silicon diaphragm placed at the tip of a single-mode fiber. Measurements in air indicate that this sensor has a relatively uniform frequency response up to at least 50 kHz, which is at least one order of magnitude higher than existing all-fiber acoustic sensors. This sensor was also shown to be able to detect pressures as low as 18 muPa/Hz 1/2. This limit is four orders of magnitude lower than in similar types of acoustic fiber sensors that are based on a deflectable diaphragm at the fiber end. This significant improvement is to a large extent due to the higher reflectivity of the reflectors, which is itself due to the use of a photonic crystal. Through a modification in the design, such a sensor can also be used in water. In addition to the high compliance of the diaphragm, the advantage for using the photonic-crystal slab is that the holes provide a venting channel for pressure equalization. As a result, the hydrophone can be employed in deep-sea applications without suffering from the high static pressure. Measurements in water over the range of 10 kHz-50 kHz show that this hydrophone has a minimum detectable pressure of only 10 muPa/Hz1/2, close to the ambient thermal-noise level. A model was developed to show that after optimization to ocean acoustics, the sensor has a theoretical minimum detectable pressure that follows the minimum ambient noise spectrum of the ocean in the bandwidth of 1 Hz-100 kHz. This makes this sensor extremely broadband compared to commercial fiber hydrophones, which are bulky and poorly responsive to frequencies above a few hundred Hz, since they require a long length of fiber. By placing several such sensors with different acoustic power ranges within a single sensor chip, this hydrophone is capable of exhibiting a dynamic range in the excess of 200 dB (1010).

  12. MS2 Virus Inactivation by Atmospheric-Pressure Cold Plasma Using Different Gas Carriers and Power Levels

    PubMed Central

    Wu, Yan; Liang, Yongdong; Wei, Kai; Li, Wei; Grinshpun, Sergey A.

    2014-01-01

    In this study, airborne MS2 bacteriophages were exposed for subsecond time intervals to atmospheric-pressure cold plasma (APCP) produced using different power levels (20, 24, and 28 W) and gas carriers (ambient air, Ar-O2 [2%, vol/vol], and He-O2 [2%, vol/vol]). In addition, waterborne MS2 viruses were directly subjected to the APCP treatment for up to 3 min. MS2 viruses with and without the APCP exposure were examined by scanning electron microscopy (SEM), reverse transcription-PCR (RT-PCR), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Viral inactivation was shown to exhibit linear relationships with the APCP generation power and exposure time (R2 > 0.95 for all energy levels tested) up to 95% inactivation (1.3-log reduction) after a subsecond airborne exposure at 28 W; about the same inactivation level was achieved for waterborne viruses with an exposure time of less than 1 min. A larger amount of reactive oxygen species (ROS), such as atomic oxygen, in APCP was detected for a higher generation power with Ar-O2 and He-O2 gas carriers. SEM images, SDS-PAGE, and agarose gel analysis of exposed waterborne viruses showed various levels of damage to both surface proteins and their related RNA genes after the APCP exposure, thus leading to the loss of their viability and infectivity. PMID:25416775

  13. R&D 100 Winner 2010: Acoustic Wave Biosensors

    ScienceCinema

    Larson, Richard; Branch, Darren; Edwards, Thayne

    2016-07-12

    The acoustic wave biosensor is innovative device that is a handheld, battery-powered, portable detection system capable of multiplex identification of a wide range of medically relevant pathogens and their biomolecular signatures — viruses, bacteria, proteins, and DNA — at clinically relevant levels. This detection occurs within minutes — not hours — at the point of care, whether that care is in a physician's office, a hospital bed, or at the scene of a biodefense or biomedical emergency.

  14. Acoustic emission frequency discrimination

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  15. Deep Water Ocean Acoustics

    DTIC Science & Technology

    2015-07-17

    under-ice scattering , bathymetric diffraction and the application of the ocean acoustic Parabolic Equation to infrasound. 2. Tasks a. Task 1...QSR-14C0172-Ocean Acoustics -063015 Figure 10. Estimated reflection coefficient as a function of frequency by taking the difference of downgoing and...OASIS, INC. 1 Report No. QSR-14C0172-Ocean Acoustics -063015 Quarterly Progress Report Technical and Financial Deep Water Ocean Acoustics

  16. Deep Water Ocean Acoustics

    DTIC Science & Technology

    2015-10-19

    OASIS, INC. 1 Report No. QSR-14C0172-Ocean Acoustics-093015 Quarterly Progress Report Technical and Financial Deep Water Ocean Acoustics...number. 1. REPORT DATE OCT 2015 2. REPORT TYPE 3. DATES COVERED 01-07-2015 to 30-09-2015 4. TITLE AND SUBTITLE Deep Water Ocean Acoustics...understanding of the impact of the ocean and seafloor environmental variability on deep- water (long-range) ocean acoustic propagation and to develop

  17. Shallow Water Acoustics Studies

    DTIC Science & Technology

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Shallow Water Acoustics Studies James F. Lynch MS #12...N00014-14-1-0040 http://acoustics.whoi.edu/sw06/ LONG TERM GOALS The long term goals of our shallow water acoustics work are to: 1) understand the...nature of low frequency (10-1500 Hz) acoustic propagation, scattering and noise in shallow water when strong oceanic variability is present in the

  18. Relative blood flow changes measured using calibrated frequency-weighted Doppler power at different hematocrit levels.

    PubMed

    Wallace, Sean; Logallo, Nicola; Faiz, Kashif W; Lund, Christian; Brucher, Rainer; Russell, David

    2014-04-01

    In theory, the power of a trans-cranial Doppler signal may be used to measure changes in blood flow and vessel diameter in addition to velocity. In this study, a flow index (FI) of relative changes in blood flow was derived from frequency-weighted Doppler power signals. The FI, plotted against velocity, was calibrated to the zero intercept with absent flow to reduce the effects of non-uniform vessel insonation. An area index was also calculated. FIs were compared with actual flow in four silicone tubes of different diameter at increasing flow rates and increasing hematocrit (Hct) in a closed-loop phantom model. FI values were strongly correlated with actual flow, at constant Hct, but varied substantially with changes in Hct. Percentage changes in area indexes, relative to the 4-mm tube, were strongly correlated with tube cross-sectional area. The implications of these results for in vivo use are discussed.

  19. Kilowatt-level cladding light stripper for high-power fiber laser.

    PubMed

    Yan, Ping; Sun, Junyi; Huang, Yusheng; Li, Dan; Wang, Xuejiao; Xiao, Qirong; Gong, Mali

    2017-03-01

    We designed and fabricated a high-power cladding light stripper (CLS) by combining a fiber-etched CLS with a cascaded polymer-recoated CLS. The etched fiber reorganizes the numerical aperture (NA) distribution of the cladding light, leading to an increase in the leakage power and a flatter distribution of the leakage proportion in the cascaded polymer-recoated fiber. The index distribution of the cascaded polymer-recoated fiber is carefully designed to ensure an even leakage of cladding light. More stages near the index of 1.451 are included to disperse the heat. The CLS is capable of working consistently under 1187 W of cladding light with an attenuation of 26.59 dB, and the highest local temperature is less than 35°C.

  20. A low power level-crossing ADC for wearable wireless ECG sensors.

    PubMed

    Zhenzhen Tian; Rendong Ying; Peilin Liu; Guoxing Wang; Yong Lian

    2016-08-01

    Ultra-low power consumption is desired in most wearable biomedical devices. The event-driven based Analog-to-Digital converter (ADC) could be an excellent candidate for low power system because of the reduction in sampling points for biosignals. In the existing event-driven based ADC architectures, two or more high precision comparators are utilized to sample the input signal. In this paper, we propose a new scheme utilizing only one high precision comparator to genertate samples with the assistance of a low precision one. From the Matlab simulations on real ECG signal, it is shown that around 25% reduction on the number of samples can be be achieved compared with the Nyquist sampling scheme.

  1. Megawatt peak power level sub-100 fs Yb:KGW oscillators.

    PubMed

    Zhao, Haitao; Major, Arkady

    2014-12-15

    We report on the first demonstration, to the best of our knowledge, of sub-100 fs pulses directly from the diode-pumped mode-locked Yb:KGW bulk oscillators operated at a low repetition rate. The 36 MHz oscillator delivered 78 fs pulses with pulse energy of 50 nJ and peak power of 0.65 MW. The cavity was extended by inserting a 1:1 imaging telescope, allowing 85 fs pulses to be generated at a repetition rate of 18 MHz. The pulse energy up to 83 nJ was reached, corresponding to a peak power as high as 1 MW. Sub-100 fs regime was achieved by dual action of the Kerr-lens and saturable absorber (KLAS) mode locking.

  2. Obesity is not associated with increased knee joint torque and power during level walking.

    PubMed

    DeVita, Paul; Hortobágyi, Tibor

    2003-09-01

    While it is widely speculated that obesity causes increased loads on the knee leading to joint degeneration, this concept is untested. The purpose of the study was to identify the effects of obesity on lower extremity joint kinetics and energetics during walking. Twenty-one obese adults were tested at self-selected (1.29m/s) and standard speeds (1.50m/s) and 18 lean adults were tested at the standard speed. Motion analysis and force platform data were combined to calculate joint torques and powers during the stance phase of walking. Obese participants were more erect with 12% less knee flexion and 11% more ankle plantarflexion in self-selected compared to standard speeds (both p<0.02). Obese participants were still more erect than lean adults with approximately 6 degrees more extension at all joints (p<0.05, for each joint) at the standard speed. Knee and ankle torques were 17% and 11% higher (p<0.034 and p<0.041) and negative knee work and positive ankle work were 68% and 11% higher (p<0.000 and p<0.048) in obese participants at the standard speed compared to the slower speed. Joint torques and powers were statistically identical at the hip and knee but were 88% and 61% higher (both p<0.000) at the ankle in obese compared to lean participants at the standard speed. Obese participants used altered gait biomechanics and despite their greater weight, they had less knee torque and power at their self-selected walking speed and equal knee torque and power while walking at the same speed as lean individuals. We propose that the ability to reorganize neuromuscular function during gait may enable some obese individuals to maintain skeletal health of the knee joint and this ability may also be a more accurate risk indicator for knee osteoarthritis than body weight.

  3. Coding Acoustic Metasurfaces.

    PubMed

    Xie, Boyang; Tang, Kun; Cheng, Hua; Liu, Zhengyou; Chen, Shuqi; Tian, Jianguo

    2017-02-01

    Coding acoustic metasurfaces can combine simple logical bits to acquire sophisticated functions in wave control. The acoustic logical bits can achieve a phase difference of exactly π and a perfect match of the amplitudes for the transmitted waves. By programming the coding sequences, acoustic metasurfaces with various functions, including creating peculiar antenna patterns and waves focusing, have been demonstrated.

  4. 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).

  5. The level of residual dispersion variation and the power of differential expression tests for RNA-Seq data.

    PubMed

    Mi, Gu; Di, Yanming

    2015-01-01

    RNA-Sequencing (RNA-Seq) has been widely adopted for quantifying gene expression changes in comparative transcriptome analysis. For detecting differentially expressed genes, a variety of statistical methods based on the negative binomial (NB) distribution have been proposed. These methods differ in the ways they handle the NB nuisance parameters (i.e., the dispersion parameters associated with each gene) to save power, such as by using a dispersion model to exploit an apparent relationship between the dispersion parameter and the NB mean. Presumably, dispersion models with fewer parameters will result in greater power if the models are correct, but will produce misleading conclusions if not. This paper investigates this power and robustness trade-off by assessing rates of identifying true differential expression using the various methods under realistic assumptions about NB dispersion parameters. Our results indicate that the relative performances of the different methods are closely related to the level of dispersion variation unexplained by the dispersion model. We propose a simple statistic to quantify the level of residual dispersion variation from a fitted dispersion model and show that the magnitude of this statistic gives hints about whether and how much we can gain statistical power by a dispersion-modeling approach.

  6. Frequency effects on the scale and behavior of acoustic streaming.

    PubMed

    Dentry, Michael B; Yeo, Leslie Y; Friend, James R

    2014-01-01

    Acoustic streaming underpins an exciting range of fluid manipulation phenomena of rapidly growing significance in microfluidics, where the streaming often assumes the form of a steady, laminar jet emanating from the device surface, driven by the attenuation of acoustic energy within the beam of sound propagating through the liquid. The frequencies used to drive such phenomena are often chosen ad hoc to accommodate fabrication and material issues. In this work, we seek a better understanding of the effects of sound frequency and power on acoustic streaming. We present and, using surface acoustic waves, experimentally verify a laminar jet model that is based on the turbulent jet model of Lighthill, which is appropriate for acoustic streaming seen at micro- to nanoscales, between 20 and 936 MHz and over a broad range of input power. Our model eliminates the critically problematic acoustic source singularity present in Lighthill's model, replacing it with a finite emission area and enabling determination of the streaming velocity close to the source. At high acoustic power P (and hence high jet Reynolds numbers ReJ associated with fast streaming), the laminar jet model predicts a one-half power dependence (U∼P1/2∼ ReJ) similar to the turbulent jet model. However, the laminar model may also be applied to jets produced at low powers-and hence low jet Reynolds numbers ReJ-where a linear relationship between the beam power and streaming velocity exists: U∼P∼ReJ2. The ability of the laminar jet model to predict the acoustic streaming behavior across a broad range of frequencies and power provides a useful tool in the analysis of microfluidics devices, explaining peculiar observations made by several researchers in the literature. In particular, by elucidating the effects of frequency on the scale of acoustically driven flows, we show that the choice of frequency is a vitally important consideration in the design of small-scale devices employing acoustic streaming

  7. Optical remote sensing and correlation of office equipment functional state and stress levels via power quality disturbances inefficiencies

    NASA Astrophysics Data System (ADS)

    Sternberg, Oren; Bednarski, Valerie R.; Perez, Israel; Wheeland, Sara; Rockway, John D.

    2016-09-01

    Non-invasive optical techniques pertaining to the remote sensing of power quality disturbances (PQD) are part of an emerging technology field typically dominated by radio frequency (RF) and invasive-based techniques. Algorithms and methods to analyze and address PQD such as probabilistic neural networks and fully informed particle swarms have been explored in industry and academia. Such methods are tuned to work with RF equipment and electronics in existing power grids. As both commercial and defense assets are heavily power-dependent, understanding electrical transients and failure events using non-invasive detection techniques is crucial. In this paper we correlate power quality empirical models to the observed optical response. We also empirically demonstrate a first-order approach to map household, office and commercial equipment PQD to user functions and stress levels. We employ a physics-based image and signal processing approach, which demonstrates measured non-invasive (remote sensing) techniques to detect and map the base frequency associated with the power source to the various PQD on a calibrated source.

  8. Staff nurses' perceptions of job empowerment and level of burnout: a test of Kanter's theory of structural power in organizations.

    PubMed

    Hatcher, S; Laschinger, H K

    1996-01-01

    Kanter's structural theory of organizational behavior was used as framework to explore the relationship between perceptions of power and opportunity and level of burnout in a sample of 87 hospital staff nurses. Data were collected using a modified version of the Conditions for Work Effectiveness Questionnaire (Chandler, 1986) and the Human Services Survey (Maslach & Jackson, 1986). Consistent with Kanter's theory, perceived access to power and opportunity was significantly related to the three aspects of burnout: level of emotional exhaustion and depersonalization (r = -.3419, p = .004; r = -.2931, p = .02), and personal accomplishments (r = .3630, p = .002). The results of this study are useful for nurse administrators positioned to create organizational structures than empower staff nurses and subsequently decrease burnout.

  9. 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.

  10. [The acoustic indicator of saliva under stress].

    PubMed

    Shalenkova, M A; Mikhaĭlova, Z D; Klemin, V A; Korkotashvili, L V; Abanin, A M; Klemina, A V; Dolgov, V V

    2014-03-01

    The situation of stress affects various organs and systems that results in development of functional disorders and/or somatic diseases. As a result, different noninvasive, including salivary, techniques of diagnostic of stress conditions are in the process of development. The dynamics of acoustic indicator of saliva is studied during the period of passing the exams. The relationship of indicator with levels of potassium, sodium, glucose and protein of saliva was analyzed. The sampling consisted of 102 students of 5 and 6 academic years of medical university. To detect the acoustic indicator of saliva acoustic analyzer AKBa-01- "BIOM" was applied. The level of potassium and sodium in saliva was detected using method of flame photometry. The level of glucose in saliva was detected by glucose oxydase technique using analyzer "EXAN-G". The protein in saliva was detected by biuretic technique. The correlation between acoustic indicator of saliva and analyzed indicators of saliva was established.

  11. Delay-dependent H∞ robust control for large power systems based on two-level hierarchical decentralised coordinated control structure

    NASA Astrophysics Data System (ADS)

    Dou, Chun-Xia; Duan, Zhi-Sheng; Jia, Xing-Bei

    2013-02-01

    This article focuses on a novel two-level hierarchical decentralised coordinated control which consists of several local fuzzy power system stabilisers (LFPSSs) for each generator at the first level tuned by supervisory power system stabiliser (SPSS) at the secondary level for the transient stabilisation improvement of large power systems. First, in order to compensate the inherent nonlinear interconnections between subsystems in system dynamic model, a direct feedback linearisation compensator is proposed to act through the local excitation machine. Afterwards, the T-S fuzzy model-based decentralised LFPSS for each generator is designed. Then, for the purpose of improving dynamic performance, the SPSS is designed by using the remote signals from the wide area measurements system. However, there are unavoidable delays involved before the remote signals are received at the SPSS site or the control signals of SPSS are sent to the local systems. Taking consideration of the multiple delays, by using less conservative delay-dependent Lyapunov approach, the authors develop a delay-dependent H∞ robust control technique based on the decentralised coordinated control structure. Some sufficient conditions for the system stabilisation are presented in terms of linear matrix inequalities dependent only on the upper bounds of the time delays. Finally, the effectiveness of the proposed control scheme is demonstrated through simulation examples.

  12. How does non-linear dynamics affect the baryon acoustic oscillation?

    SciTech Connect

    Sugiyama, Naonori S.; Spergel, David N. E-mail: dns@astro.princeton.edu

    2014-02-01

    We study the non-linear behavior of the baryon acoustic oscillation in the power spectrum and the correlation function by decomposing the dark matter perturbations into the short- and long-wavelength modes. The evolution of the dark matter fluctuations can be described as a global coordinate transformation caused by the long-wavelength displacement vector acting on short-wavelength matter perturbation undergoing non-linear growth. Using this feature, we investigate the well known cancellation of the high-k solutions in the standard perturbation theory. While the standard perturbation theory naturally satisfies the cancellation of the high-k solutions, some of the recently proposed improved perturbation theories do not guarantee the cancellation. We show that this cancellation clarifies the success of the standard perturbation theory at the 2-loop order in describing the amplitude of the non-linear power spectrum even at high-k regions. We propose an extension of the standard 2-loop level perturbation theory model of the non-linear power spectrum that more accurately models the non-linear evolution of the baryon acoustic oscillation than the standard perturbation theory. The model consists of simple and intuitive parts: the non-linear evolution of the smoothed power spectrum without the baryon acoustic oscillations and the non-linear evolution of the baryon acoustic oscillations due to the large-scale velocity of dark matter and due to the gravitational attraction between dark matter particles. Our extended model predicts the smoothing parameter of the baryon acoustic oscillation peak at z = 0.35 as ∼ 7.7Mpc/h and describes the small non-linear shift in the peak position due to the galaxy random motions.

  13. Finite difference solutions to shocked acoustic waves

    NASA Technical Reports Server (NTRS)

    Walkington, N. J.; Eversman, W.

    1983-01-01

    The MacCormack, Lambda and split flux finite differencing schemes are used to solve a one dimensional acoustics problem. Two duct configurations were considered, a uniform duct and a converging-diverging nozzle. Asymptotic solutions for these two ducts are compared with the numerical solutions. When the acoustic amplitude and frequency are sufficiently high the acoustic signal shocks. This condition leads to a deterioration of the numerical solutions since viscous terms may be required if the shock is to be resolved. A continuous uniform duct solution is considered to demonstrate how the viscous terms modify the solution. These results are then compared with a shocked solution with and without viscous terms. Generally it is found that the most accurate solutions are those obtained using the minimum possible viscosity coefficients. All of the schemes considered give results accurate enough for acoustic power calculations with no one scheme performing significantly better than the others.

  14. A computational approach for flow-acoustic coupling in closed side branches.

    PubMed

    Radavich, P M; Selamet, A; Novak, J M

    2001-04-01

    The quarter-wave resonator, which produces a narrow band of high acoustic attenuation at regularly spaced frequency intervals, is a common type of silencer used in ducts. The presence of mean flow in the main duct, however, is likely to promote an interaction between these acoustic resonances and the flow. The coupling for some discrete flow conditions leads to the production of both large wave amplitudes in the side branch and high noise levels in the main duct, thereby transforming the quarter-wave silencer into a noise generator. The present approach employs computational fluid dynamics (CFD) to model this complex interaction between the flow and acoustic resonances at low Mach number by solving the unsteady, turbulent, and compressible Navier-Stokes equations. Comparisons between the present computations and the experiments of Ziada [PVP-Vol. 258, ASME, 35-59 (1993)] for a system with two coaxial side branches show that the method is capable of reproducing the physics of the flow-acoustic coupling and predicting the flow conditions when the coupling occurs. The theory of Howe [IMA J. Appl. Math. 32, 187-209 (1984)] is then employed to determine the location and timing of the acoustic power production during a cycle.

  15. Challenges and regulatory considerations in the acoustic measurement of high-frequency (>20 MHz) ultrasound.

    PubMed

    Nagle, Samuel M; Sundar, Guru; Schafer, Mark E; Harris, Gerald R; Vaezy, Shahram; Gessert, James M; Howard, Samuel M; Moore, Mary K; Eaton, Richard M

    2013-11-01

    This article examines the challenges associated with making acoustic output measurements at high ultrasound frequencies (>20 MHz) in the context of regulatory considerations contained in the US Food and Drug Administration industry guidance document for diagnostic ultrasound devices. Error sources in the acoustic measurement, including hydrophone calibration and spatial averaging, nonlinear distortion, and mechanical alignment, are evaluated, and the limitations of currently available acoustic measurement instruments are discussed. An uncertainty analysis of acoustic intensity and power measurements is presented, and an example uncertainty calculation is done on a hypothetical 30-MHz high-frequency ultrasound system. This analysis concludes that the estimated measurement uncertainty of the acoustic intensity is +73%/-86%, and the uncertainty in the mechanical index is +37%/-43%. These values exceed the respective levels in the Food and Drug Administration guidance document of 30% and 15%, respectively, which are more representative of the measurement uncertainty associated with characterizing lower-frequency ultrasound systems. Recommendations made for minimizing the measurement uncertainty include implementing a mechanical positioning system that has sufficient repeatability and precision, reconstructing the time-pressure waveform via deconvolution using the hydrophone frequency response, and correcting for hydrophone spatial averaging.

  16. On the acoustics of a circulation control airfoil

    NASA Astrophysics Data System (ADS)

    Reger, R.; Nickels, A.; Ukeiley, L.; Cattafesta, L. N.

    2017-02-01

    A two-dimensional elliptical circulation control airfoil model is studied in the Florida State Aeroacoustic Tunnel. Far-field acoustics are obtained via a 55 microphone phased array. Single microphone spectra are also obtained, and it is shown that background noise is significant. In order to circumvent this problem, beamforming is employed. The primary sources of background noise are from the tunnel collector and jet/sidewall interaction. The deconvolution approach to mapping acoustic sources (DAMAS) is employed to remove the effects of the array point spread function. Spectra are acquired by integrating the DAMAS result over the source region. The resulting DAMAS spectral levels are significantly below single microphone levels. Although the DAMAS levels are reduced from those of a single microphone or delay and sum beamforming (DAS), they are still above those of a NACA 0012, estimated using NAFNoise, at the same geometric and free-stream conditions. A scaling analysis is performed on the processed array data. With a constant free-stream velocity and a varying jet velocity the data scale as jet Mach number to the 6th power. If the momentum coefficient is held constant and the free-stream velocity is varied the data scale as free-stream Mach number to the 7th power.

  17. An Energy Harvesting Underwater Acoustic Transmitter for Aquatic Animals

    SciTech Connect

    Li, Huidong; Tian, Chuan; Lu, Jun; Myjak, Mitchell J.; Martinez, Jayson J.; Brown, Richard S.; Deng, Zhiqun Daniel

    2016-09-20

    This paper presents a self-powered underwater acoustic transmitter using a piezoelectric beam to harvest the mechanical energy from fish swimming. This transmitter does not require a battery and is demonstrated in live fish. It transmits an acoustic waveform as the implanted fish swims. It enables long-term monitoring of aquatic animals.

  18. Frequency effects on the scale and behavior of acoustic streaming

    NASA Astrophysics Data System (ADS)

    Dentry, Michael B.; Yeo, Leslie Y.; Friend, James R.

    2014-01-01

    Acoustic streaming underpins an exciting range of fluid manipulation phenomena of rapidly growing significance in microfluidics, where the streaming often assumes the form of a steady, laminar jet emanating from the device surface, driven by the attenuation of acoustic energy within the beam of sound propagating through the liquid. The frequencies used to drive such phenomena are often chosen ad hoc to accommodate fabrication and material issues. In this work, we seek a better understanding of the effects of sound frequency and power on acoustic streaming. We present and, using surface acoustic waves, experimentally verify a laminar jet model that is based on the turbulent jet model of Lighthill, which is appropriate for acoustic streaming seen at micro- to nanoscales, between 20 and 936 MHz and over a broad range of input power. Our model eliminates the critically problematic acoustic source singularity present in Lighthill's model, replacing it with a finite emission area and enabling determination of the streaming velocity close to the source. At high acoustic power P (and hence high jet Reynolds numbers ReJ associated with fast streaming), the laminar jet model predicts a one-half power dependence (U ˜P1/2˜ ReJ) similar to the turbulent jet model. However, the laminar model may also be applied to jets produced at low powers—and hence low jet Reynolds numbers ReJ—where a linear relationship between the beam power and streaming velocity exists: U ˜P˜ReJ2. The ability of the laminar jet model to predict the acoustic streaming behavior across a broad range of frequencies and power provides a useful tool in the analysis of microfluidics devices, explaining peculiar observations made by several researchers in the literature. In particular, by elucidating the effects of frequency on the scale of acoustically driven flows, we show that the choice of frequency is a vitally important consideration in the design of small-scale devices employing acoustic streaming

  19. Analysis of High Cadence In Situ Solar Wind Ionic Composition Data Using Wavelet Power Spectra Confidence Levels

    NASA Astrophysics Data System (ADS)

    Edmondson, J. K.; Lynch, B. J.; Lepri, S. T.; Zurbuchen, T. H.

    2013-12-01

    The variability inherent in solar wind composition has implications for the variability of the physical conditions in its coronal source regions, providing constraints on models of coronal heating and solar wind generation. We present a generalized prescription for constructing a wavelet power significance measure (confidence level) for the purpose of characterizing the effects of missing data in high cadence solar wind ionic composition measurements. We describe the data gaps present in the 12 minute Advanced Composition Explorer/Solar Wind Ionic Composition Spectrometer observations of O7 +/O6 + during 2008. The decomposition of the in situ observations into "good measurement" and "no-measurement" signals allows us to evaluate the performance of a filler signal, i.e., various prescriptions for filling the data gaps. We construct Monte Carlo simulations of synthetic O7 +/O6 + composition data and impose the actual data gaps that exist in the observations in order to investigate two different filler signals: one, a linear interpolation between neighboring good data points, and two, the constant mean value of the measured data. Applied to these synthetic data plus filler signal combinations, we quantify the ability of the power spectra significance level procedure to reproduce the ensemble-averaged time-integrated wavelet power per scale of an ideal case, i.e., the synthetic data without imposed data gaps. Finally, we present the wavelet power spectra for the O7 +/O6 + data using the confidence levels derived from both the mean value and linear interpolation data gap filling signals and discuss the results.

  20. Measurement and Characterization of Space Shuttle Solid Rocket Motor Plume Acoustics

    NASA Technical Reports Server (NTRS)

    Kenny, Jeremy; Hobbs, Chris; Plotkin, Ken; Pilkey, Debbie

    2009-01-01

    Lift-off acoustic environments generated by the future Ares I launch vehicle are assessed by the NASA Marshall Space Flight Center (MSFC) acoustics team using several prediction tools. This acoustic environment is directly caused by the Ares I First Stage booster, powered by the five-segment Reusable Solid Rocket Motor (RSRMV). The RSRMV is a larger-thrust derivative design from the currently used Space Shuttle solid rocket motor, the Reusable Solid Rocket Motor (RSRM). Lift-off acoustics is an integral part of the composite launch vibration environment affecting the Ares launch vehicle and must be assessed to help generate hardware qualification levels and ensure structural integrity of the vehicle during launch and lift-off. Available prediction tools that use free field noise source spectrums as a starting point for generation of lift-off acoustic environments are described in the monograph NASA SP-8072: "Acoustic Loads Generated by the Propulsion System." This monograph uses a reference database for free field noise source spectrums which consist of subscale rocket motor firings, oriented in horizontal static configurations. The phrase "subscale" is appropriate, since the thrust levels of rockets in the reference database are orders of magnitude lower than the current design thrust for the Ares launch family. Thus, extrapolation is needed to extend the various reference curves to match Ares-scale acoustic levels. This extrapolation process yields a subsequent amount of uncertainty added upon the acoustic environment predictions. As the Ares launch vehicle design schedule progresses, it is important to take every opportunity to lower prediction uncertainty and subsequently increase prediction accuracy. Never before in NASA s history has plume acoustics been measured for large scale solid rocket motors. Approximately twice a year, the RSRM prime vendor, ATK Launch Systems, static fires an assembled RSRM motor in a horizontal configuration at their test facility