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Sample records for high-frequency recoil spectrometer

  1. Time-of-flight direct recoil ion scattering spectrometer

    DOEpatents

    Krauss, Alan R.; Gruen, Dieter M.; Lamich, George J.

    1994-01-01

    A time of flight direct recoil and ion scattering spectrometer beam line (10). The beam line (10) includes an ion source (12) which injects ions into pulse deflection regions (14) and (16) separated by a drift space (18). A final optics stage includes an ion lens and deflection plate assembly (22). The ion pulse length and pulse interval are determined by computerized adjustment of the timing between the voltage pulses applied to the pulsed deflection regions (14) and (16).

  2. Time-of-flight direct recoil ion scattering spectrometer

    DOEpatents

    Krauss, A.R.; Gruen, D.M.; Lamich, G.J.

    1994-09-13

    A time-of-flight direct recoil and ion scattering spectrometer beam line is disclosed. The beam line includes an ion source which injects ions into pulse deflection regions and separated by a drift space. A final optics stage includes an ion lens and deflection plate assembly. The ion pulse length and pulse interval are determined by computerized adjustment of the timing between the voltage pulses applied to the pulsed deflection regions. 23 figs.

  3. A Recoil Mass Spectrometer for the HHIRF facility

    SciTech Connect

    Cole, J.D. ); Cormier, T.M. ); Hamilton, J.H. . Dept. of Physics and Astronomy)

    1989-01-01

    A Recoil Mass Spectrometer (RMS) is to be built that will carry out a broad research program in heavy-ion science. The RMS will make possible the study of otherwise inaccessible exotic nuclei. Careful attention has been given to match the RMS to all the beams available from the HHIRF accelerators, including those beams with the highest energy, as well as massive particles for use in inverse reactions. The RMS is to be a momentum achromat followed by a split electric-dipole mass spectrometer of the type operating at NSRL at the University of Rochester. The RMS is essential for many of the proposed experiments on short-lived and/or low cross-section products. The spectrometer design is discussed, with examples and comparisons with other spectrometers given. Detector arrays to be used with the RMS are also discussed. 21 refs., 4 figs., 1 tab.

  4. Calibration of a compact magnetic proton recoil neutron spectrometer

    NASA Astrophysics Data System (ADS)

    Zhang, Jianfu; Ouyang, Xiaoping; Zhang, Xianpeng; Ruan, Jinlu; Zhang, Guoguang; Zhang, Xiaodong; Qiu, Suizheng; Chen, Liang; Liu, Jinliang; Song, Jiwen; Liu, Linyue; Yang, Shaohua

    2016-04-01

    Magnetic proton recoil (MPR) neutron spectrometer is considered as a powerful instrument to measure deuterium-tritium (DT) neutron spectrum, as it is currently used in inertial confinement fusion facilities and large Tokamak devices. The energy resolution (ER) and neutron detection efficiency (NDE) are the two most important parameters to characterize a neutron spectrometer. In this work, the ER calibration for the MPR spectrometer was performed by using the HI-13 tandem accelerator at China Institute of Atomic Energy (CIAE), and the NDE calibration was performed by using the neutron generator at CIAE. The specific calibration techniques used in this work and the associated accuracies were discussed in details in this paper. The calibration results were presented along with Monte Carlo simulation results.

  5. A telescope proton recoil spectrometer for fast neutron beam-lines

    NASA Astrophysics Data System (ADS)

    Cazzaniga, C.; Rebai, M.; Tardocchi, M.; Croci, G.; Nocente, M.; Ansell, S.; Frost, C. D.; Gorini, G.

    2015-07-01

    Fast neutron measurements were performed on the VESUVIO beam-line at the ISIS spallation source using a new telescope proton recoil spectrometer. Neutrons interact on a plastic target. Proton production is mainly due to elastic scattering on hydrogen nuclei and secondly due to interaction with carbon nuclei. Recoil protons are measured by a proton spectrometer, which uses in coincidence a 2.54 cm thick YAP scintillator and a 500μm thick silicon detector, measuring the full proton recoil energy and the partial deposited energy in transmission, respectively. Recoil proton spectroscopy measurements (up to Ep = 60MeV) have been interpreted by using Monte Carlo simulations of the beam-line. This instrument is of particular interest for the characterization of the ChipIr beam-line at ISIS, which was designed to feature an atmospheric-like neutron spectrum for the irradiation of micro-electronics.

  6. Four pi-recoil proportional counter used as neutron spectrometer

    NASA Technical Reports Server (NTRS)

    Bennett, E. F.

    1968-01-01

    Study considers problems encountered in using 4 pi-recoil counters for neutron spectra measurement. Emphasis is placed on calibration, shape discrimination, variation of W, the average energy loss per ion pair, and the effects of differentiation on the intrinsic counter resolution.

  7. EMMA, a Recoil Mass Spectrometer for TRIUMF's ISAC-II Facility

    NASA Astrophysics Data System (ADS)

    Davids, Barry; EMMA Collaboration

    2016-09-01

    EMMA is a recoil mass spectrometer for TRIUMF's ISAC-II facility in the final stages of installation and commissioning. In this talk I will briefly review the spectrometer's design capabilities, describe recent progress in its installation and commissioning, and discuss plans for its initial experimental program. This work was supported by the Natural Sciences and Engineering Council of Canada. TRIUMF receives federal funds through a contribution agreement with the National Research Council of Canada.

  8. A focal-plane detector for the recoil-mass spectrometer of LNL

    NASA Astrophysics Data System (ADS)

    Guerrieri, A.; Maron, G.; Montagnoli, G.; Napoli, D. R.; Prete, G.

    1990-12-01

    A focal-plane detector for a recoil-mass spectrometer has been developed. It consists of a 14 × 14 cm 2 position-sensitive parallel-plate avalanche counter backed by a 43 cm long Bragg chamber. Both detectors work in the same gas volume thus reducing the dead layers. The intrinsic resolution of the position detector is ±0.5 mm, and an overall timing resolution of 660 ps FWHM was measured with 5.5 MeV α-particles. The Bragg chamber allows the identification of elements with energy high enough to overcome the Bragg peak: in all cases it allows the separation between the reaction channels and the beam scattering. The detector has already been used with a good reliability in a variety of transfer and fusion experiments at the LNL Recoil Mass Spectrometer.

  9. EMMA: A recoil mass spectrometer for ISAC-II at TRIUMF

    NASA Astrophysics Data System (ADS)

    Davids, Barry; Davids, Cary N.

    2005-06-01

    Design work has begun on EMMA, an electromagnetic mass analyzer for ISAC-II at TRIUMF. EMMA is a recoil mass spectrometer that will be used to separate the recoils of nuclear reactions from the beam, and to disperse them according to mass/charge. ISAC-II will provide intense, low-emittance beams of unstable nuclei with masses up to 150 u and maximum energies of at least 6.5 MeV/nucleon. EMMA will be used in many different types of experiments with radioactive beams, especially those involving fusion-evaporation and transfer reactions. As such, it must be both efficient and selective, possessing large acceptances in angle, mass, and energy without sacrificing the necessary beam suppression and mass resolution.

  10. Development of a compact magnetic proton recoil spectrometer for measurement of deuterium-tritium neutrons

    SciTech Connect

    Zhang, Jianfu Ouyang, Xiaoping; Zhang, Xianpeng; Qiu, Suizheng; Zhang, Guoguang; Ruan, Jinlu; Zhang, Xiaodong; Yang, Shaohua; Song, Jiwen; Liu, Linyue; Li, Hongyun

    2015-12-15

    A new compact magnetic proton recoil (MPR) neutron spectrometer has been designed for precise measurement of deuterium-tritium (DT) neutrons. This design is presented emphasizing the magnetic analyzing system, which is based on a compact quadrupole-dipole (QD) electromagnet. The focal plane detector (FPD) is also discussed with respect to application for the next step. The characteristics of the MPR spectrometer were calculated by using Monte Carlo simulation. A preliminary experiment was performed to test the magnetic analyzing system and the proton images of the FPD. Since the QD electromagnet design allows for a larger foil thickness and solid angle to be utilized, the MPR spectrometer defined in this paper can achieve neutron detection efficiency more than 5 × 10{sup −7} at an energy resolution of 1.5% for measuring DT neutrons.

  11. Development of a compact magnetic proton recoil spectrometer for measurement of deuterium-tritium neutrons.

    PubMed

    Zhang, Jianfu; Ouyang, Xiaoping; Qiu, Suizheng; Zhang, Guoguang; Ruan, Jinlu; Zhang, Xiaodong; Zhang, Xianpeng; Yang, Shaohua; Song, Jiwen; Liu, Linyue; Li, Hongyun

    2015-12-01

    A new compact magnetic proton recoil (MPR) neutron spectrometer has been designed for precise measurement of deuterium-tritium (DT) neutrons. This design is presented emphasizing the magnetic analyzing system, which is based on a compact quadrupole-dipole (QD) electromagnet. The focal plane detector (FPD) is also discussed with respect to application for the next step. The characteristics of the MPR spectrometer were calculated by using Monte Carlo simulation. A preliminary experiment was performed to test the magnetic analyzing system and the proton images of the FPD. Since the QD electromagnet design allows for a larger foil thickness and solid angle to be utilized, the MPR spectrometer defined in this paper can achieve neutron detection efficiency more than 5 × 10(-7) at an energy resolution of 1.5% for measuring DT neutrons.

  12. The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF

    NASA Astrophysics Data System (ADS)

    Casey, D. T.; Frenje, J. A.; Gatu Johnson, M.; Séguin, F. H.; Li, C. K.; Petrasso, R. D.; Glebov, V. Yu.; Katz, J.; Magoon, J.; Meyerhofer, D. D.; Sangster, T. C.; Shoup, M.; Ulreich, J.; Ashabranner, R. C.; Bionta, R. M.; Carpenter, A. C.; Felker, B.; Khater, H. Y.; LePape, S.; MacKinnon, A.; McKernan, M. A.; Moran, M.; Rygg, J. R.; Yeoman, M. F.; Zacharias, R.; Leeper, R. J.; Fletcher, K.; Farrell, M.; Jasion, D.; Kilkenny, J.; Paguio, R.

    2013-04-01

    The neutron spectrum produced by deuterium-tritium (DT) inertial confinement fusion implosions contains a wealth of information about implosion performance including the DT yield, ion-temperature, and areal-density. The Magnetic Recoil Spectrometer (MRS) has been used at both the OMEGA laser facility and the National Ignition Facility (NIF) to measure the absolute neutron spectrum from 3 to 30 MeV at OMEGA and 3 to 36 MeV at the NIF. These measurements have been used to diagnose the performance of cryogenic target implosions to unprecedented accuracy. Interpretation of MRS data requires a detailed understanding of the MRS response and background. This paper describes ab initio characterization of the system involving Monte Carlo simulations of the MRS response in addition to the commission experiments for in situ calibration of the systems on OMEGA and the NIF.

  13. The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF.

    PubMed

    Casey, D T; Frenje, J A; Johnson, M Gatu; Séguin, F H; Li, C K; Petrasso, R D; Glebov, V Yu; Katz, J; Magoon, J; Meyerhofer, D D; Sangster, T C; Shoup, M; Ulreich, J; Ashabranner, R C; Bionta, R M; Carpenter, A C; Felker, B; Khater, H Y; LePape, S; MacKinnon, A; McKernan, M A; Moran, M; Rygg, J R; Yeoman, M F; Zacharias, R; Leeper, R J; Fletcher, K; Farrell, M; Jasion, D; Kilkenny, J; Paguio, R

    2013-04-01

    The neutron spectrum produced by deuterium-tritium (DT) inertial confinement fusion implosions contains a wealth of information about implosion performance including the DT yield, ion-temperature, and areal-density. The Magnetic Recoil Spectrometer (MRS) has been used at both the OMEGA laser facility and the National Ignition Facility (NIF) to measure the absolute neutron spectrum from 3 to 30 MeV at OMEGA and 3 to 36 MeV at the NIF. These measurements have been used to diagnose the performance of cryogenic target implosions to unprecedented accuracy. Interpretation of MRS data requires a detailed understanding of the MRS response and background. This paper describes ab initio characterization of the system involving Monte Carlo simulations of the MRS response in addition to the commission experiments for in situ calibration of the systems on OMEGA and the NIF.

  14. The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF

    SciTech Connect

    Casey, D. T.; Frenje, J. A.; Gatu Johnson, M.; Seguin, F. H.; Li, C. K.; Petrasso, R. D.; Glebov, V. Yu.; Katz, J.; Magoon, J.; Meyerhofer, D. D.; Sangster, T. C.; Shoup, M.; Ulreich, J.; Ashabranner, R. C.; Bionta, R. M.; Carpenter, A. C.; Felker, B.; Khater, H. Y.; LePape, S.; MacKinnon, A.; and others

    2013-04-15

    The neutron spectrum produced by deuterium-tritium (DT) inertial confinement fusion implosions contains a wealth of information about implosion performance including the DT yield, ion-temperature, and areal-density. The Magnetic Recoil Spectrometer (MRS) has been used at both the OMEGA laser facility and the National Ignition Facility (NIF) to measure the absolute neutron spectrum from 3 to 30 MeV at OMEGA and 3 to 36 MeV at the NIF. These measurements have been used to diagnose the performance of cryogenic target implosions to unprecedented accuracy. Interpretation of MRS data requires a detailed understanding of the MRS response and background. This paper describes ab initio characterization of the system involving Monte Carlo simulations of the MRS response in addition to the commission experiments for in situ calibration of the systems on OMEGA and the NIF.

  15. The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF

    DOE PAGES

    Casey, D. T.; Frenje, J. A.; Gatu Johnson, M.; ...

    2013-04-18

    The neutron spectrum produced by deuterium-tritium (DT) inertial confinement fusion implosions contains a wealth of information about implosion performance including the DT yield, iontemperature, and areal-density. The Magnetic Recoil Spectrometer (MRS) has been used at both the OMEGA laser facility and the National Ignition Facility (NIF) to measure the absolute neutron spectrum from 3 to 30 MeV at OMEGA and 3 to 36 MeV at the NIF. These measurements have been used to diagnose the performance of cryogenic target implosions to unprecedented accuracy. Interpretation of MRS data requires a detailed understanding of the MRS response and background. This paper describesmore » ab initio characterization of the system involving Monte Carlo simulations of the MRS response in addition to the commission experiments for in situ calibration of the systems on OMEGA and the NIF.« less

  16. Measuring the absolute DT neutron yield using the Magnetic Recoil Spectrometer at OMEGA and the NIF

    SciTech Connect

    Mackinnon, A; Casey, D; Frenje, J A; Johnson, M G; Seguin, F H; Li, C K; Petrasso, R D; Glebov, V Y; Katz, J; Knauer, J; Meyerhofer, D; Sangster, T; Bionta, R; Bleuel, D; Hachett, S P; Hartouni, E; Lepape, S; Mckernan, M; Moran, M; Yeamans, C

    2012-05-03

    A Magnetic Recoil Spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion (ICF) implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.

  17. The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF

    SciTech Connect

    Casey, D. T.; Frenje, J. A.; Gatu Johnson, M.; Seguin, F. H.; Li, C. K.; Petrasso, R. D.; Glebov, V. Yu.; Katz, J.; Magoon, J.; Meyerhofer, D. D.; Sangster, T. C.; Shoup, M.; Ulreich, J.; Ashabranner, R. C.; Bionta, R. M.; Carpenter, A. C.; Felker, B.; Khater, H. Y.; LePape, S.; MacKinnon, A.; McKernan, M. A.; Moran, M.; Rygg, J. R.; Yeoman, M. F.; Zacharias, R.; Leeper, R. J.; Fletcher, K.; Farrell, M.; Jasion, D.; Kilkenny, J.; Paguio, R.

    2013-04-18

    The neutron spectrum produced by deuterium-tritium (DT) inertial confinement fusion implosions contains a wealth of information about implosion performance including the DT yield, iontemperature, and areal-density. The Magnetic Recoil Spectrometer (MRS) has been used at both the OMEGA laser facility and the National Ignition Facility (NIF) to measure the absolute neutron spectrum from 3 to 30 MeV at OMEGA and 3 to 36 MeV at the NIF. These measurements have been used to diagnose the performance of cryogenic target implosions to unprecedented accuracy. Interpretation of MRS data requires a detailed understanding of the MRS response and background. This paper describes ab initio characterization of the system involving Monte Carlo simulations of the MRS response in addition to the commission experiments for in situ calibration of the systems on OMEGA and the NIF.

  18. Detection Efficiency of a ToF Spectrometer from Heavy-Ion Elastic Recoil Detection

    SciTech Connect

    Barbara, E. de; Marti, G. V.; Capurro, O. A.; Fimiani, L.; Mingolla, M. G.; Negri, A. E.; Arazi, A.; Figueira, J. M.; Pacheco, A. J.; Martinez Heimann, D.; Carnelli, P. F. F.; Fernandez Niello, J. O.

    2010-08-04

    The detection efficiency of a time-of-flight system based on two micro-channel plates (MCP) time zero detectors plus a conventional silicon surface barrier detector was obtained from heavy ion elastic recoil measurements (this ToF spectrometer is mainly devoted to measurements of total fusion cross section of weakly bound projectiles on different mass-targets systems). In this work we have used beams of {sup 7}Li, {sup 16}O, {sup 32}S and {sup 35}Cl to study the mass region of interest for its application to measurements fusion cross sections in the {sup 6,7}Li+{sup 27}Al systems at energies around and above the Coulomb barrier (0.8V{sub B{<=}}E{<=}2.0V{sub B}). As the efficiency of a ToF spectrometer is strongly dependent on the energy and mass of the detected particles, we have covered a wide range of the scattered particle energies with a high degree of accuracy at the lowest energies. The different experimental efficiency curves obtained in that way were compared with theoretical electronic stopping power curves on carbon foils and were applied.

  19. A recoil ion momentum spectrometer for molecular and atomic fragmentation studies

    SciTech Connect

    Khan, Arnab; Tribedi, Lokesh C.; Misra, Deepankar

    2015-04-15

    We report the development and performance studies of a newly built recoil ion momentum spectrometer for the study of atomic and molecular fragmentation dynamics in gas phase upon the impact of charged particles and photons. The present design is a two-stage Wiley-McLaren type spectrometer which satisfies both time and velocity focusing conditions and is capable of measuring singly charged ionic fragments up-to 13 eV in all directions. An electrostatic lens has been introduced in order to achieve velocity imaging. Effects of the lens on time-of-flight as well as on the position have been investigated in detail, both, by simulation and in experiment. We have used 120 keV proton beam on molecular nitrogen gas target. Complete momentum distributions and kinetic energy release distributions have been derived from the measured position and time-of-flight spectra. Along with this, the kinetic energy release spectra of fragmentation of doubly ionized nitrogen molecule upon various projectile impacts are presented.

  20. A recoil ion momentum spectrometer for molecular and atomic fragmentation studies

    NASA Astrophysics Data System (ADS)

    Khan, Arnab; Tribedi, Lokesh C.; Misra, Deepankar

    2015-04-01

    We report the development and performance studies of a newly built recoil ion momentum spectrometer for the study of atomic and molecular fragmentation dynamics in gas phase upon the impact of charged particles and photons. The present design is a two-stage Wiley-McLaren type spectrometer which satisfies both time and velocity focusing conditions and is capable of measuring singly charged ionic fragments up-to 13 eV in all directions. An electrostatic lens has been introduced in order to achieve velocity imaging. Effects of the lens on time-of-flight as well as on the position have been investigated in detail, both, by simulation and in experiment. We have used 120 keV proton beam on molecular nitrogen gas target. Complete momentum distributions and kinetic energy release distributions have been derived from the measured position and time-of-flight spectra. Along with this, the kinetic energy release spectra of fragmentation of doubly ionized nitrogen molecule upon various projectile impacts are presented.

  1. A stretch/compress scheme for a high temporal resolution detector for the magnetic recoil spectrometer time (MRSt).

    PubMed

    Hilsabeck, T J; Frenje, J A; Hares, J D; Wink, C W

    2016-11-01

    A time-resolved detector concept for the magnetic recoil spectrometer for time-resolved measurements of the NIF neutron spectrum is presented. The measurement is challenging due to the time spreading of the recoil protons (or deuterons) as they transit an energy dispersing magnet system. Ions arrive at the focal plane of the magnetic spectrometer over an interval of tens of nanoseconds. We seek to measure the time-resolved neutron spectrum with 20 ps precision by manipulating an electron signal derived from the ions. A stretch-compress scheme is employed to remove transit time skewing while simultaneously reducing the bandwidth requirements for signal recording. Simulation results are presented along with design concepts for structures capable of establishing the required electromagnetic fields.

  2. A stretch/compress scheme for a high temporal resolution detector for the magnetic recoil spectrometer time (MRSt)

    DOE PAGES

    Hilsabeck, T. J.; Frenje, J. A.; Hares, J. D.; ...

    2016-08-02

    Here we present a time-resolved detector concept for the magnetic recoil spectrometer for time-resolved measurements of the NIF neutron spectrum. The measurement is challenging due to the time spreading of the recoil protons (or deuterons) as they transit an energy dispersing magnet system. Ions arrive at the focal plane of the magnetic spectrometer over an interval of tens of nanoseconds. We seek to measure the time-resolved neutron spectrum with 20 ps precision by manipulating an electron signal derived from the ions. A stretch-compress scheme is employed to remove transit time skewing while simultaneously reducing the bandwidth requirements for signal recording.more » Simulation results are presented along with design concepts for structures capable of establishing the required electromagnetic fields.« less

  3. A stretch/compress scheme for a high temporal resolution detector for the magnetic recoil spectrometer time (MRSt)

    SciTech Connect

    Hilsabeck, T. J.; Frenje, J. A.; Hares, J. D.; Wink, C. W.

    2016-08-02

    Here we present a time-resolved detector concept for the magnetic recoil spectrometer for time-resolved measurements of the NIF neutron spectrum. The measurement is challenging due to the time spreading of the recoil protons (or deuterons) as they transit an energy dispersing magnet system. Ions arrive at the focal plane of the magnetic spectrometer over an interval of tens of nanoseconds. We seek to measure the time-resolved neutron spectrum with 20 ps precision by manipulating an electron signal derived from the ions. A stretch-compress scheme is employed to remove transit time skewing while simultaneously reducing the bandwidth requirements for signal recording. Simulation results are presented along with design concepts for structures capable of establishing the required electromagnetic fields.

  4. A stretch/compress scheme for a high temporal resolution detector for the magnetic recoil spectrometer time (MRSt)

    NASA Astrophysics Data System (ADS)

    Hilsabeck, T. J.; Frenje, J. A.; Hares, J. D.; Wink, C. W.

    2016-11-01

    A time-resolved detector concept for the magnetic recoil spectrometer for time-resolved measurements of the NIF neutron spectrum is presented. The measurement is challenging due to the time spreading of the recoil protons (or deuterons) as they transit an energy dispersing magnet system. Ions arrive at the focal plane of the magnetic spectrometer over an interval of tens of nanoseconds. We seek to measure the time-resolved neutron spectrum with 20 ps precision by manipulating an electron signal derived from the ions. A stretch-compress scheme is employed to remove transit time skewing while simultaneously reducing the bandwidth requirements for signal recording. Simulation results are presented along with design concepts for structures capable of establishing the required electromagnetic fields.

  5. A stretch/compress scheme for a high temporal resolution detector for the magnetic recoil spectrometer time (MRSt)

    SciTech Connect

    Hilsabeck, T. J.; Frenje, J. A.; Hares, J. D.; Wink, C. W.

    2016-08-02

    Here we present a time-resolved detector concept for the magnetic recoil spectrometer for time-resolved measurements of the NIF neutron spectrum. The measurement is challenging due to the time spreading of the recoil protons (or deuterons) as they transit an energy dispersing magnet system. Ions arrive at the focal plane of the magnetic spectrometer over an interval of tens of nanoseconds. We seek to measure the time-resolved neutron spectrum with 20 ps precision by manipulating an electron signal derived from the ions. A stretch-compress scheme is employed to remove transit time skewing while simultaneously reducing the bandwidth requirements for signal recording. Simulation results are presented along with design concepts for structures capable of establishing the required electromagnetic fields.

  6. Upgrading a high-throughput spectrometer for high-frequency (<400 kHz) measurements

    NASA Astrophysics Data System (ADS)

    Nishizawa, T.; Nornberg, M. D.; Den Hartog, D. J.; Craig, D.

    2016-11-01

    The upgraded spectrometer used for charge exchange recombination spectroscopy on the Madison Symmetric Torus resolves emission fluctuations up to 400 kHz. The transimpedance amplifier's cutoff frequency was increased based upon simulations comparing the change in the measured photon counts for time-dynamic signals. We modeled each signal-processing stage of the diagnostic and scanned the filtering frequency to quantify the uncertainty in the photon counting rate. This modeling showed that uncertainties can be calculated based on assuming each amplification stage is a Poisson process and by calibrating the photon counting rate with a DC light source to address additional variation.

  7. Upgrading a high-throughput spectrometer for high-frequency (<400 kHz) measurements

    SciTech Connect

    Nishizawa, T. Nornberg, M. D.; Den Hartog, D. J.; Craig, D.

    2016-11-15

    The upgraded spectrometer used for charge exchange recombination spectroscopy on the Madison Symmetric Torus resolves emission fluctuations up to 400 kHz. The transimpedance amplifier’s cutoff frequency was increased based upon simulations comparing the change in the measured photon counts for time-dynamic signals. We modeled each signal-processing stage of the diagnostic and scanned the filtering frequency to quantify the uncertainty in the photon counting rate. This modeling showed that uncertainties can be calculated based on assuming each amplification stage is a Poisson process and by calibrating the photon counting rate with a DC light source to address additional variation.

  8. Improvements in Fabrication of Elastic Scattering Foils Used to Measure Neutron Yield by the Magnetic Recoil Spectrometer

    DOE PAGES

    Reynolds, H. G.; Schoff, M. E.; Farrell, M. P.; ...

    2016-08-01

    The magnetic recoil spectrometer uses a deuterated polyethylene polymer (CD2) foil to measure neutron yield in inertial confinement fusion experiments. Higher neutron yields in recent experiments have resulted in primary signal saturation in the detector CR-39 foils, necessitating the fabrication of thinner CD2 foils than established methods could provide. A novel method of fabricating deuterated polymer foils is described. The resulting foils are thinner, smoother, and more uniform in thickness than the foils produced by previous methods. Here, these new foils have successfully been deployed at the National Ignition Facility, enabling higher neutron yield measurements than previous foils, with nomore » primary signal saturation.« less

  9. Improvements in Fabrication of Elastic Scattering Foils Used to Measure Neutron Yield by the Magnetic Recoil Spectrometer

    SciTech Connect

    Reynolds, H. G.; Schoff, M. E.; Farrell, M. P.; Gatu Johnson, M.; Bionta, R. M.; Frenje, J. A.

    2016-08-01

    The magnetic recoil spectrometer uses a deuterated polyethylene polymer (CD2) foil to measure neutron yield in inertial confinement fusion experiments. Higher neutron yields in recent experiments have resulted in primary signal saturation in the detector CR-39 foils, necessitating the fabrication of thinner CD2 foils than established methods could provide. A novel method of fabricating deuterated polymer foils is described. The resulting foils are thinner, smoother, and more uniform in thickness than the foils produced by previous methods. Here, these new foils have successfully been deployed at the National Ignition Facility, enabling higher neutron yield measurements than previous foils, with no primary signal saturation.

  10. Improvements in Fabrication of Elastic Scattering Foils Used to Measure Neutron Yield by the Magnetic Recoil Spectrometer

    SciTech Connect

    Reynolds, H. G.; Schoff, M. E.; Farrell, M. P.; Gatu Johnson, M.; Bionta, R. M.; Frenje, J. A.

    2016-08-01

    The magnetic recoil spectrometer uses a deuterated polyethylene polymer (CD2) foil to measure neutron yield in inertial confinement fusion experiments. Higher neutron yields in recent experiments have resulted in primary signal saturation in the detector CR-39 foils, necessitating the fabrication of thinner CD2 foils than established methods could provide. A novel method of fabricating deuterated polymer foils is described. The resulting foils are thinner, smoother, and more uniform in thickness than the foils produced by previous methods. Here, these new foils have successfully been deployed at the National Ignition Facility, enabling higher neutron yield measurements than previous foils, with no primary signal saturation.

  11. The magnetic recoil spectrometer (MRSt) for time-resolved measurements of the neutron spectrum at the National Ignition Facility (NIF)

    SciTech Connect

    Frenje, J. A.; Hilsabeck, T. J.; Wink, C. W.; Bell, P.; Bionta, R.; Cerjan, C.; Gatu Johnson, M.; Kilkenny, J. D.; Li, C. K.; Séguin, F. H.; Petrasso, R. D.

    2016-08-02

    The next-generation magnetic recoil spectrometer for time-resolved measurements of the neutron spectrum has been conceptually designed for the National Ignition Facility. This spectrometer, called MRSt, represents a paradigm shift in our thinking about neutron spectrometry for inertial confinement fusion applications, as it will provide simultaneously information about the burn history and time evolution of areal density (ρR), apparent ion temperature (Ti), yield (Yn), and macroscopic flows during burn. From this type of data, an assessment of the evolution of the fuel assembly, hotspot, and alpha heating can be made. According to simulations, the MRSt will provide accurate data with a time resolution of ~20 ps and energy resolution of ~100 keV for total neutron yields above ~1016. Lastly, at lower yields, the diagnostic will be operated at a higher-efficiency, lower-energy-resolution mode to provide a time resolution of ~20 ps.

  12. The magnetic recoil spectrometer (MRSt) for time-resolved measurements of the neutron spectrum at the National Ignition Facility (NIF).

    PubMed

    Frenje, J A; Hilsabeck, T J; Wink, C W; Bell, P; Bionta, R; Cerjan, C; Gatu Johnson, M; Kilkenny, J D; Li, C K; Séguin, F H; Petrasso, R D

    2016-11-01

    The next-generation magnetic recoil spectrometer for time-resolved measurements of the neutron spectrum has been conceptually designed for the National Ignition Facility. This spectrometer, called MRSt, represents a paradigm shift in our thinking about neutron spectrometry for inertial confinement fusion applications, as it will provide simultaneously information about the burn history and time evolution of areal density (ρR), apparent ion temperature (Ti), yield (Yn), and macroscopic flows during burn. From this type of data, an assessment of the evolution of the fuel assembly, hotspot, and alpha heating can be made. According to simulations, the MRSt will provide accurate data with a time resolution of ∼20 ps and energy resolution of ∼100 keV for total neutron yields above ∼10(16). At lower yields, the diagnostic will be operated at a higher-efficiency, lower-energy-resolution mode to provide a time resolution of ∼20 ps.

  13. The magnetic recoil spectrometer (MRSt) for time-resolved measurements of the neutron spectrum at the National Ignition Facility (NIF)

    NASA Astrophysics Data System (ADS)

    Frenje, J. A.; Hilsabeck, T. J.; Wink, C. W.; Bell, P.; Bionta, R.; Cerjan, C.; Gatu Johnson, M.; Kilkenny, J. D.; Li, C. K.; Séguin, F. H.; Petrasso, R. D.

    2016-11-01

    The next-generation magnetic recoil spectrometer for time-resolved measurements of the neutron spectrum has been conceptually designed for the National Ignition Facility. This spectrometer, called MRSt, represents a paradigm shift in our thinking about neutron spectrometry for inertial confinement fusion applications, as it will provide simultaneously information about the burn history and time evolution of areal density (ρR), apparent ion temperature (Ti), yield (Yn), and macroscopic flows during burn. From this type of data, an assessment of the evolution of the fuel assembly, hotspot, and alpha heating can be made. According to simulations, the MRSt will provide accurate data with a time resolution of ˜20 ps and energy resolution of ˜100 keV for total neutron yields above ˜1016. At lower yields, the diagnostic will be operated at a higher-efficiency, lower-energy-resolution mode to provide a time resolution of ˜20 ps.

  14. The magnetic recoil spectrometer (MRSt) for time-resolved measurements of the neutron spectrum at the National Ignition Facility (NIF)

    SciTech Connect

    Frenje, J. A. Wink, C. W.; Gatu Johnson, M.; Li, C. K.; Séguin, F. H.; Petrasso, R. D.; Hilsabeck, T. J.; Kilkenny, J. D.; Bell, P.; Bionta, R.; Cerjan, C.

    2016-11-15

    The next-generation magnetic recoil spectrometer for time-resolved measurements of the neutron spectrum has been conceptually designed for the National Ignition Facility. This spectrometer, called MRSt, represents a paradigm shift in our thinking about neutron spectrometry for inertial confinement fusion applications, as it will provide simultaneously information about the burn history and time evolution of areal density (ρR), apparent ion temperature (T{sub i}), yield (Y{sub n}), and macroscopic flows during burn. From this type of data, an assessment of the evolution of the fuel assembly, hotspot, and alpha heating can be made. According to simulations, the MRSt will provide accurate data with a time resolution of ∼20 ps and energy resolution of ∼100 keV for total neutron yields above ∼10{sup 16}. At lower yields, the diagnostic will be operated at a higher-efficiency, lower-energy-resolution mode to provide a time resolution of ∼20 ps.

  15. The magnetic recoil spectrometer (MRSt) for time-resolved measurements of the neutron spectrum at the National Ignition Facility (NIF)

    SciTech Connect

    Frenje, J. A.; Hilsabeck, T. J.; Wink, C. W.; Bell, P.; Bionta, R.; Cerjan, C.; Gatu Johnson, M.; Kilkenny, J. D.; Li, C. K.; Séguin, F. H.; Petrasso, R. D.

    2016-08-02

    The next-generation magnetic recoil spectrometer for time-resolved measurements of the neutron spectrum has been conceptually designed for the National Ignition Facility. This spectrometer, called MRSt, represents a paradigm shift in our thinking about neutron spectrometry for inertial confinement fusion applications, as it will provide simultaneously information about the burn history and time evolution of areal density (ρR), apparent ion temperature (Ti), yield (Yn), and macroscopic flows during burn. From this type of data, an assessment of the evolution of the fuel assembly, hotspot, and alpha heating can be made. According to simulations, the MRSt will provide accurate data with a time resolution of ~20 ps and energy resolution of ~100 keV for total neutron yields above ~1016. Lastly, at lower yields, the diagnostic will be operated at a higher-efficiency, lower-energy-resolution mode to provide a time resolution of ~20 ps.

  16. The magnetic recoil spectrometer (MRSt) for time-resolved measurements of the neutron spectrum at the National Ignition Facility (NIF)

    DOE PAGES

    Frenje, J. A.; Hilsabeck, T. J.; Wink, C. W.; ...

    2016-08-02

    The next-generation magnetic recoil spectrometer for time-resolved measurements of the neutron spectrum has been conceptually designed for the National Ignition Facility. This spectrometer, called MRSt, represents a paradigm shift in our thinking about neutron spectrometry for inertial confinement fusion applications, as it will provide simultaneously information about the burn history and time evolution of areal density (ρR), apparent ion temperature (Ti), yield (Yn), and macroscopic flows during burn. From this type of data, an assessment of the evolution of the fuel assembly, hotspot, and alpha heating can be made. According to simulations, the MRSt will provide accurate data with amore » time resolution of ~20 ps and energy resolution of ~100 keV for total neutron yields above ~1016. Lastly, at lower yields, the diagnostic will be operated at a higher-efficiency, lower-energy-resolution mode to provide a time resolution of ~20 ps.« less

  17. In situ high-frequency UV-Vis spectrometer probes for investigating runoff processes and end member stability.

    NASA Astrophysics Data System (ADS)

    Schwab, Michael; Weiler, Markus; Pfister, Laurent; Klaus, Julian

    2014-05-01

    In recent years, several limitations as to the application of end member mixing analysis with isotope and geochemical tracers have been revealed: unstable end member solutions, inputs varying in space and time, and unrealistic mixing assumptions. In addition, the necessary high-frequency sampling using conventional methods is time and resources consuming, and hence most sampling rates are not suitable for capturing the response times of the majority of observed headwater catchments. However, high-frequency observations are considered fundamental for gaining new insights into hydrological systems. In our study, we have used two portable, in situ, high-frequency UV-Vis spectrometers (spectro::lyser; scan Messtechnik GmbH) to investigate the variability of several signatures in streamflow and end member stability. The spectro::lyser measures TOC, DOC, nitrate and the light absorption spectrum from 220 to 720 nm with 2.5 nm increment. The Weierbach catchment (0.45 km2) in the Attert basin (297 km2) in Luxemburg is a small headwater research catchment (operated by the CRP Gabriel Lippmann), which is completely forested and underlain by schist bedrock. The catchment is equipped with a dense network of hydrological instruments and for this study, the outlet of the Weierbach catchment was equipped with one spectro::lyser, permanently sensing stream water at a 15 minutes time step over several months. Hydrometric and meteorologic data was compared with the high-frequency spectro::lyser time series of TOC, DOC, nitrate and the light absorption spectrum, to get a first insight into the behaviour of the catchment under different environmental conditions. As a preliminary step for a successful end member mixing analysis, the stability of rainfall, soil water, and groundwater was tested with one spectro::lyser, both temporally and spatially. Thereby, we focused on the investigation of changes and patterns of the light absorption spectrum of the different end members and the

  18. Measuring the absolute deuterium-tritium neutron yield using the magnetic recoil spectrometer at OMEGA and the NIF

    SciTech Connect

    Casey, D. T.; Frenje, J. A.; Gatu Johnson, M.; Seguin, F. H.; Li, C. K.; Petrasso, R. D.; Glebov, V. Yu.; Katz, J.; Knauer, J. P.; Meyerhofer, D. D.; Sangster, T. C.; Bionta, R. M.; Bleuel, D. L.; Doeppner, T.; Glenzer, S.; Hartouni, E.; Hatchett, S. P.; Le Pape, S.; Ma, T.; MacKinnon, A.; and others

    2012-10-15

    A magnetic recoil spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.

  19. Measuring the absolute deuterium-tritium neutron yield using the magnetic recoil spectrometer at OMEGA and the NIF.

    PubMed

    Casey, D T; Frenje, J A; Gatu Johnson, M; Séguin, F H; Li, C K; Petrasso, R D; Glebov, V Yu; Katz, J; Knauer, J P; Meyerhofer, D D; Sangster, T C; Bionta, R M; Bleuel, D L; Döppner, T; Glenzer, S; Hartouni, E; Hatchett, S P; Le Pape, S; Ma, T; MacKinnon, A; McKernan, M A; Moran, M; Moses, E; Park, H-S; Ralph, J; Remington, B A; Smalyuk, V; Yeamans, C B; Kline, J; Kyrala, G; Chandler, G A; Leeper, R J; Ruiz, C L; Cooper, G W; Nelson, A J; Fletcher, K; Kilkenny, J; Farrell, M; Jasion, D; Paguio, R

    2012-10-01

    A magnetic recoil spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.

  20. Use of the ECL-CAMAC trigger processor system for recoil missing mass triggers at the Tagged Photon Spectrometer at Fermilab

    SciTech Connect

    Martin, J.; Bracker, S.; Hartner, G.; Appel, J.; Nash, T.

    1981-05-01

    A trigger processor in operation since May 1980 at the Tagged Photon Spectrometer at Fermilab will be described. The processor, based on the Fermilab ECL-CAMAC system, allows fast selection of high mass diffractive events from the total hadronic cross section. Data from a recoil detector, consisting of 3 wire chambers and 4 layers of scintillator concentric about a 1.5 m liquid hydrogen target, is digitized and presented to the processor within 3 sec. From the chamber data are found the vertices and angles of all recoiling tracks.

  1. Commissioning of a new timestamp-based data acquisition system for the DRAGON recoil mass spectrometer

    NASA Astrophysics Data System (ADS)

    Christian, Gregory; Akers, Charlie; Connolly, Devin; Fallis, Jennifer; Hutcheon, Dave; Olchanski, Konstantin; Ruiz, Chris

    2014-09-01

    The DRAGON recoil mass separator at TRIUMF exists to study radiative proton and alpha capture reactions, which are important in a variety of astrophysical scenarios. DRAGON experiments require a data acquisition system that can be triggered on either reaction product (γ ray or heavy ion), with the additional requirement of being able to promptly recognize coincidence events in an online environment. To this end, we have designed and implemented a new data acquisition system for DRAGON which consists of two independently triggered readouts. Events from both systems are recorded with timestamps from a 20 MHz clock that are used to tag coincidences in the earliest possible stage of the data analysis. In this talk, I will discuss the design, implementation, and commissioning of the new DRAGON data acquisition system, focusing specifically on the trigger logic, coincidence reconstruction algorithm and live time considerations. I will also discuss the results of an experiment commissioning the new system, which measured the strength of the Ecm = 1113 keV resonance in the 20Ne(p , γ) 21Na radiative proton capture reaction.

  2. A continuous mode data acquisition technique for proton recoil proportional counter neutron spectrometers

    SciTech Connect

    Bennett, E.F.

    1989-03-01

    The existing proton recoil proportional counter measurement technique used at FNS for joint FNS-ANL fusion blanket neutron spectroscopy requires that numerous piece-wise (but overlapping) measurements be carried out at a sequence of fixed counter voltages. The composite results of all of these independent measurements are required to construct a single neutron spectrum. This approach has been found to be both inefficient and subject to systematic errors. An alternative approach, in which data is acquired continuously using a slow time modulation of the high voltage bias supply, is here described. The electronics requirements are consistent with the basic detector/amplifier systems now operable at FNS. Some additional hardware including a programmable high voltage bias supply and a random amplitude test pulse generator are necessary. A description of the electronics and data acquisition hardware for these measurements will be provided at a later date. In this report we emphasize the numerical procedures involved to acquire and reduce data, and provide an illustrative example using one of the hardest neutron spectra readily available for this work at ANL. 6 refs., 26 figs.

  3. Optimized shielding design for the time-resolved Magnetic Recoil Spectrometer (MRSt) on the NIF

    NASA Astrophysics Data System (ADS)

    Wink, C.; Frenje, J.; Gatu Johnson, M.; Li, C. K.; Seguin, F.; Petrasso, R.; Hilsabeck, T.; Bionta, R.; Khater, H.

    2016-10-01

    To meet the goals for the MRSt to measure the neutron spectrum at the NIF with a time resolution of 20 ps and an accuracy of 5%, a S/B >5 for the down-scattered neutron measurement is required. As the MRSt-detector design consists of a pulse-dilation drift tube with a CsI photocathode positioned at the focal plane of the spectrometer and a microchannel plate (MCP) for signal gain, the S/B requirement can be met if the number of secondary electrons (SE) produced by neutron and γ-ray background in these components is reduced 50-100 times. It has been shown in ref. that the SE generated by the neutron and γ-ray background in the CsI is insignificant and won't affect the MRSt measurement. However, the MCP poses a greater S/B challenge due to higher background sensitivities. In this paper, we discuss an MRSt SE generation model, which includes the CsI photocathode and MCP, and the MRSt shielding design required to reduce the MCP background to the required level for a down-scattered neutron measurement. This work was supported in part by DOE (NNSA, NLUF) and LLNL.

  4. Real time high frequency monitoring of water quality in river streams using a UV-visible spectrometer: interest, limits and consequences for monitoring strategies

    NASA Astrophysics Data System (ADS)

    Faucheux, Mikaël; Fovet, Ophélie; Gruau, Gérard; Jaffrézic, Anne; Petitjean, Patrice; Gascuel-Odoux, Chantal; Ruiz, Laurent

    2013-04-01

    Stream water chemistry is highly variable in space and time, therefore high frequency water quality measurement methods are likely to lead to conceptual advances in the hydrological sciences. Sub-daily data on water quality improve the characterization of pollutant sources and pathways during flood events as well as during long-term periods [1]. However, real time, high frequency monitoring devices needs to be properly calibrated and validated in real streams. This study analyses data from in situ monitoring of a stream water quality. During two hydrological years (2010-11, 2011-12), a submersible UV-visible spectrometer (Scan Spectrolyser) was used for surface water quality measurement at the outlet of a headwater catchment located at Kervidy-Naizin, Western France (AgrHys long-term hydrological observatory, http://www.inra.fr/ore_agrhys/). The spectrometer is reagentless and equipped with an auto-cleaning system. It allows real time, in situ and high frequency (20 min) measurements and uses a multiwavelengt spectral (200-750 nm) for simultaneous measurement of nitrate, dissolved organic carbon (DOC) and total suspended solids (TSS). A global calibration based on a PLS (Partial Least Squares) regression is provided by the manufacturer as default configuration of the UV-visible spectrometer. We carried out a local calibration of the spectrometer based on nitrates and DOC concentrations analysed in the laboratory from daily manual sampling and sub-daily automatic sampling of flood events. TSS results are compared with 15 min turbidity records from a continuous turdidimeter (Ponsel). The results show a good correlation between laboratory data and spectrometer data both during basis flows periods and flood events. However, the local calibration gives better results than the global one. Nutrient fluxes estimates based on high and different low frequency time series (daily to monthly) are compared to discuss the implication for environmental monitoring strategies. Such

  5. High-resolution measurements of the DT neutron spectrum using new CD foils in the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Gatu Johnson, M.; Frenje, J. A.; Bionta, R. M.; Casey, D. T.; Eckart, M. J.; Farrell, M. P.; Grim, G. P.; Hartouni, E. P.; Hatarik, R.; Hoppe, M.; Kilkenny, J. D.; Li, C. K.; Petrasso, R. D.; Reynolds, H. G.; Sayre, D. B.; Schoff, M. E.; Séguin, F. H.; Skulina, K.; Yeamans, C. B.

    2016-11-01

    The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility measures the DT neutron spectrum from cryogenically layered inertial confinement fusion implosions. Yield, areal density, apparent ion temperature, and directional fluid flow are inferred from the MRS data. This paper describes recent advances in MRS measurements of the primary peak using new, thinner, reduced-area deuterated plastic (CD) conversion foils. The new foils allow operation of MRS at yields 2 orders of magnitude higher than previously possible, at a resolution down to ˜200 keV FWHM.

  6. High-resolution measurements of the DT neutron spectrum using new CD foils in the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility.

    PubMed

    Gatu Johnson, M; Frenje, J A; Bionta, R M; Casey, D T; Eckart, M J; Farrell, M P; Grim, G P; Hartouni, E P; Hatarik, R; Hoppe, M; Kilkenny, J D; Li, C K; Petrasso, R D; Reynolds, H G; Sayre, D B; Schoff, M E; Séguin, F H; Skulina, K; Yeamans, C B

    2016-11-01

    The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility measures the DT neutron spectrum from cryogenically layered inertial confinement fusion implosions. Yield, areal density, apparent ion temperature, and directional fluid flow are inferred from the MRS data. This paper describes recent advances in MRS measurements of the primary peak using new, thinner, reduced-area deuterated plastic (CD) conversion foils. The new foils allow operation of MRS at yields 2 orders of magnitude higher than previously possible, at a resolution down to ∼200 keV FWHM.

  7. High-resolution measurements of the DT neutron spectrum using new CD foils in the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility

    SciTech Connect

    Gatu Johnson, M. Frenje, J. A.; Li, C. K.; Petrasso, R. D.; Séguin, F. H.; Bionta, R. M.; Casey, D. T.; Eckart, M. J.; Grim, G. P.; Hartouni, E. P.; Hatarik, R.; Sayre, D. B.; Skulina, K.; Yeamans, C. B.; Farrell, M. P.; Hoppe, M.; Kilkenny, J. D.; Reynolds, H. G.; Schoff, M. E.

    2016-11-15

    The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility measures the DT neutron spectrum from cryogenically layered inertial confinement fusion implosions. Yield, areal density, apparent ion temperature, and directional fluid flow are inferred from the MRS data. This paper describes recent advances in MRS measurements of the primary peak using new, thinner, reduced-area deuterated plastic (CD) conversion foils. The new foils allow operation of MRS at yields 2 orders of magnitude higher than previously possible, at a resolution down to ∼200 keV FWHM.

  8. High-resolution measurements of the DT neutron spectrum using new CD foils in the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility

    DOE PAGES

    Gatu Johnson, M.; Frenje, J. A.; Bionta, R. M.; ...

    2016-08-09

    The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility measures the DT neutron spectrum from cryogenically layered inertial confinement fusion implosions. Yield, areal density, apparent ion temperature, and directional fluid flow are inferred from the MRS data. Here, this paper describes recent advances in MRS measurements of the primary peak using new, thinner, reduced-area deuterated plastic (CD) conversion foils. The new foils allow operation of MRS at yields 2 orders of magnitude higher than previously possible, at a resolution down to ~200 keV FWHM.

  9. The coincidence counting technique for orders of magnitude background reduction in data obtained with the magnetic recoil spectrometer at OMEGA and the NIF.

    PubMed

    Casey, D T; Frenje, J A; Séguin, F H; Li, C K; Rosenberg, M J; Rinderknecht, H; Manuel, M J-E; Gatu Johnson, M; Schaeffer, J C; Frankel, R; Sinenian, N; Childs, R A; Petrasso, R D; Glebov, V Yu; Sangster, T C; Burke, M; Roberts, S

    2011-07-01

    A magnetic recoil spectrometer (MRS) has been built and successfully used at OMEGA for measurements of down-scattered neutrons (DS-n), from which an areal density in both warm-capsule and cryogenic-DT implosions have been inferred. Another MRS is currently being commissioned on the National Ignition Facility (NIF) for diagnosing low-yield tritium-hydrogen-deuterium implosions and high-yield DT implosions. As CR-39 detectors are used in the MRS, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). The coincidence counting technique was developed to reduce these types of background tracks to the required level for the DS-n measurements at OMEGA and the NIF. Using this technique, it has been demonstrated that the number of background tracks is reduced by a couple of orders of magnitude, which exceeds the requirement for the DS-n measurements at both facilities.

  10. Measurements of fuel and ablator ρR in Symmetry-Capsule implosions with the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility

    SciTech Connect

    Gatu Johnson, M. Frenje, J. A.; Li, C. K.; Séguin, F. H.; Petrasso, R. D.; Bionta, R. M.; Casey, D. T.; Caggiano, J. A.; Hatarik, R.; Khater, H. Y.; Sayre, D. B.; Knauer, J. P.; Sangster, T. C.; Herrmann, H. W.; Kilkenny, J. D.

    2014-11-15

    The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility (NIF) measures the neutron spectrum in the energy range of 4–20 MeV. This paper describes MRS measurements of DT-fuel and CH-ablator ρR in DT gas-filled symmetry-capsule implosions at the NIF. DT-fuel ρR's of 80–140 mg/cm{sup 2} and CH-ablator ρR's of 400–680 mg/cm{sup 2} are inferred from MRS data. The measurements were facilitated by an improved correction of neutron-induced background in the low-energy part of the MRS spectrum. This work demonstrates the accurate utilization of the complete MRS-measured neutron spectrum for diagnosing NIF DT implosions.

  11. Measurements of fuel and ablator ρR in Symmetry-Capsule implosions with the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Gatu Johnson, M.; Frenje, J. A.; Li, C. K.; Séguin, F. H.; Petrasso, R. D.; Bionta, R. M.; Casey, D. T.; Caggiano, J. A.; Hatarik, R.; Khater, H. Y.; Sayre, D. B.; Knauer, J. P.; Sangster, T. C.; Herrmann, H. W.; Kilkenny, J. D.

    2014-11-01

    The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility (NIF) measures the neutron spectrum in the energy range of 4-20 MeV. This paper describes MRS measurements of DT-fuel and CH-ablator ρR in DT gas-filled symmetry-capsule implosions at the NIF. DT-fuel ρR's of 80-140 mg/cm2 and CH-ablator ρR's of 400-680 mg/cm2 are inferred from MRS data. The measurements were facilitated by an improved correction of neutron-induced background in the low-energy part of the MRS spectrum. This work demonstrates the accurate utilization of the complete MRS-measured neutron spectrum for diagnosing NIF DT implosions.

  12. Measurements of fuel and ablator ρR in Symmetry-Capsule implosions with the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility.

    PubMed

    Gatu Johnson, M; Frenje, J A; Li, C K; Séguin, F H; Petrasso, R D; Bionta, R M; Casey, D T; Caggiano, J A; Hatarik, R; Khater, H Y; Sayre, D B; Knauer, J P; Sangster, T C; Herrmann, H W; Kilkenny, J D

    2014-11-01

    The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility (NIF) measures the neutron spectrum in the energy range of 4-20 MeV. This paper describes MRS measurements of DT-fuel and CH-ablator ρR in DT gas-filled symmetry-capsule implosions at the NIF. DT-fuel ρR's of 80-140 mg/cm(2) and CH-ablator ρR's of 400-680 mg/cm(2) are inferred from MRS data. The measurements were facilitated by an improved correction of neutron-induced background in the low-energy part of the MRS spectrum. This work demonstrates the accurate utilization of the complete MRS-measured neutron spectrum for diagnosing NIF DT implosions.

  13. A novel double-focusing time-of-flight mass spectrometer for absolute recoil ion cross sections measurements.

    PubMed

    Sigaud, L; de Jesus, V L B; Ferreira, Natalia; Montenegro, E C

    2016-08-01

    In this work, the inclusion of an Einzel-like lens inside the time-of-flight drift tube of a standard mass spectrometer coupled to a gas cell-to study ionization of atoms and molecules by electron impact-is described. Both this lens and a conical collimator are responsible for further focalization of the ions and charged molecular fragments inside the spectrometer, allowing a much better resolution at the time-of-flight spectra, leading to a separation of a single mass-to-charge unit up to 100 a.m.u. The procedure to obtain the overall absolute efficiency of the spectrometer and micro-channel plate detector is also discussed.

  14. A novel double-focusing time-of-flight mass spectrometer for absolute recoil ion cross sections measurements

    SciTech Connect

    Sigaud, L.; Jesus, V. L. B. de; Ferreira, Natalia

    2016-08-15

    In this work, the inclusion of an Einzel-like lens inside the time-of-flight drift tube of a standard mass spectrometer coupled to a gas cell—to study ionization of atoms and molecules by electron impact—is described. Both this lens and a conical collimator are responsible for further focalization of the ions and charged molecular fragments inside the spectrometer, allowing a much better resolution at the time-of-flight spectra, leading to a separation of a single mass-to-charge unit up to 100 a.m.u. The procedure to obtain the overall absolute efficiency of the spectrometer and micro-channel plate detector is also discussed.

  15. FieldSpec: A field portable mass spectrometer prototype for high frequency measurements of δ (2) H and δ (18) O ratios in water

    NASA Astrophysics Data System (ADS)

    López Días, Veneranda; Quang Hoang, Hung; Martínez-Carreras, Núria; Barnich, François; Wirtz, Tom; Pfister, Laurent; McDonnell, Jeffrey

    2016-04-01

    Hydrological studies relying on stable water isotopes to better understand water sources, flowpaths and transit times are currently limited by the coarse temporal resolution of sampling and analysis protocols. At present, two kinds of lab-based instruments are used : (i) the standard isotope ratio mass spectrometers (IRMS) [1] and (ii) the laser-based instruments [2, 3]. In both cases, samples need to be collected in the field and then transferred to the laboratory for the water isotopic ratio measurements (even further complex sample preparation is required for the IRMS). Hence, past and ongoing research targets the development of field deployable instruments for measuring stable water isotopes at high temporal frequencies. While recent studies have demonstrated that laser-based instruments may be taken to the field [4, 5], their size and power consumption still restrict their use to sites equipped with mains power or generators. Here, we present progress on the development of a field portable mass spectrometer (FieldSpec) for direct high frequency measurements of δ2H and δ18O ratios in water. The FieldSpec instrument is based upon the use of a double focusing magnetic sector mass spectrometer in combination with an electron impact ion source and a membrane dual inlet system. The instrument directly collects liquid water samples in the field, which are then converted into water vapour before being injected into the mass spectrometer for the stable isotope analysis. δ2H and δ18O are derived from the measured mass spectra. All the components are arranged in a vacuum case having a suit case type dimension with portable electronics and battery. Proof-of-concept experiments have been carried out to characterize the instrument. The results show that the FieldSpec instrument has good linearity (R2 = 0.99). The reproducibility of the instrument ranges between 1 and 4 ‰ for δ2H and between 0.1 and 0.4 ‰ for δ18O isotopic ratio measurements. A measurement

  16. Investigation of neutron-induced background in Magnetic-Recoil-Spectrometer CR-39 data using a DT neutron source and MCNP simulations

    NASA Astrophysics Data System (ADS)

    Milanese, Lucio M.; Frenje, Johan; Gatu Johnson, Maria; Lahmann, Brandon; Sio, Hong; Petrasso, Richard

    2015-11-01

    The Magnetic Recoil neutron Spectrometers (MRS) installed on the OMEGA laser facility and the National Ignition Facility (NIF) are routinely used to measure neutron yield, areal density and ion temperatures from DT implosions. The observed background in the lower-energy part of MRS spectra is significantly higher than expected from analysis of neutron-induced background data obtained in stand-alone CR-39 experiments at OMEGA. A possible explanation relates to the scattering of neutrons in the MRS housing vessel, which is not accounted for in current modeling. To test experimentally the impact of individual vessel components on the observed background, parts of the MRS housing have been mocked up and CR-39 data have been collected employing a DT neutron source. The experimental results are contrasted to MCNP simulations to improve our understanding of the mechanism behind the enhanced neutron background. The results will be used to correct measured spectra from OMEGA and the NIF to allow detailed analysis of lower energy data. This work was supported in part by NLUF, US DOE, and LLE.

  17. High Frequency Design Considerations for the Large Detector Number and Small Form Factor Dual Electron Spectrometer of the Fast Plasma Investigation on NASA's Magnetospheric Multiscale Mission

    NASA Technical Reports Server (NTRS)

    Kujawski, Joseph T.; Gliese, Ulrik B.; Cao, N. T.; Zeuch, M. A.; White, D.; Chornay, D. J; Lobell, J. V.; Avanov, L. A.; Barrie, A. C.; Mariano, A. J.; Tucker, C. J.; Piepgrass, B.; Auletti, C.; Weidner, S.; Jacques, A. D.; Pollock, C. J.

    2015-01-01

    Each half of the Dual Electron Spectrometer (DES) of the Fast Plasma Investigation (FPI) on NASA's Magnetospheric MultiScale (MMS) mission utilizes a microchannel plate Chevron stack feeding 16 separate detection channels each with a dedicated anode and amplifier/discriminator chip. The desire to detect events on a single channel with a temporal spacing of 100 ns and a fixed dead-time drove our decision to use an amplifier/discriminator with a very fast (GHz class) front end. Since the inherent frequency response of each pulse in the output of the DES microchannel plate system also has frequency components above a GHz, this produced a number of design constraints not normally expected in electronic systems operating at peak speeds of 10 MHz. Additional constraints are imposed by the geometry of the instrument requiring all 16 channels along with each anode and amplifier/discriminator to be packaged in a relatively small space. We developed an electrical model for board level interactions between the detector channels to allow us to design a board topology which gave us the best detection sensitivity and lowest channel to channel crosstalk. The amplifier/discriminator output was designed to prevent the outputs from one channel from producing triggers on the inputs of other channels. A number of Radio Frequency design techniques were then applied to prevent signals from other subsystems (e.g. the high voltage power supply, command and data handling board, and Ultraviolet stimulation for the MCP) from generating false events. These techniques enabled us to operate the board at its highest sensitivity when operated in isolation and at very high sensitivity when placed into the overall system.

  18. Forward fitting of experimental data from a NE213 neutron detector installed with the magnetic proton recoil upgraded spectrometer at JETa)

    NASA Astrophysics Data System (ADS)

    Binda, F.; Ericsson, G.; Eriksson, J.; Hellesen, C.; Conroy, S.; Sundén, E. Andersson

    2014-11-01

    In this paper, we present the results obtained from the data analysis of neutron spectra measured with a NE213 liquid scintillator at JET. We calculated the neutron response matrix of the instrument combining MCNPX simulations, a generic proton light output function measured with another detector and the fit of data from ohmic pulses. For the analysis, we selected a set of pulses with neutral beam injection heating (NBI) only and we applied a forward fitting procedure of modeled spectral components to extract the fraction of thermal neutron emission. The results showed the same trend of the ones obtained with the dedicated spectrometer TOFOR, even though the values from the NE213 analysis were systematically higher. This discrepancy is probably due to the different lines of sight of the two spectrometers (tangential for the NE213, vertical for TOFOR). The uncertainties on the thermal fraction estimates were from 4 to 7 times higher than the ones from the TOFOR analysis.

  19. Forward fitting of experimental data from a NE213 neutron detector installed with the magnetic proton recoil upgraded spectrometer at JET

    SciTech Connect

    Binda, F. Ericsson, G.; Eriksson, J.; Hellesen, C.; Conroy, S.; Sundén, E. Andersson; Collaboration: JET-EFDA Team

    2014-11-15

    In this paper, we present the results obtained from the data analysis of neutron spectra measured with a NE213 liquid scintillator at JET. We calculated the neutron response matrix of the instrument combining MCNPX simulations, a generic proton light output function measured with another detector and the fit of data from ohmic pulses. For the analysis, we selected a set of pulses with neutral beam injection heating (NBI) only and we applied a forward fitting procedure of modeled spectral components to extract the fraction of thermal neutron emission. The results showed the same trend of the ones obtained with the dedicated spectrometer TOFOR, even though the values from the NE213 analysis were systematically higher. This discrepancy is probably due to the different lines of sight of the two spectrometers (tangential for the NE213, vertical for TOFOR). The uncertainties on the thermal fraction estimates were from 4 to 7 times higher than the ones from the TOFOR analysis.

  20. Beam-recoil polarization transfer in the nucleon resonance region in the exclusive e→p→e'K+Λ→ and e→p→e'K+Σ→0 reactions at the CLAS spectrometer

    NASA Astrophysics Data System (ADS)

    Carman, D. S.; Raue, B. A.; Adhikari, K. P.; Amaryan, M. J.; Anghinolfi, M.; Baghdasaryan, H.; Battaglieri, M.; Bellis, M.; Biselli, A. S.; Bookwalter, C.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Cole, P. L.; Collins, P.; Crede, V.; Daniel, A.; Dashyan, N.; de Vita, R.; de Sanctis, E.; Deur, A.; Dhamija, S.; Djalali, C.; Dodge, G. E.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fradi, A.; Gabrielyan, M. Y.; Giovanetti, K. L.; Girod, F. X.; Gohn, W.; Gonenc, A.; Gothe, R. W.; Hakobyan, H.; Hanretty, C.; Hassall, N.; Hicks, K.; Holtrop, M.; Ilieva, Y.; Ireland, D. G.; Jo, H. S.; Johnstone, J. R.; Khetarpal, P.; Kim, W.; Kubarovsky, V.; Kuznetsov, V.; Livingston, K.; Mayer, M.; McCracken, M. E.; Meyer, C. A.; Mikhailov, K.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Moreno, B.; Moriya, K.; Moteabbed, M.; Nadel-Turonski, P.; Niccolai, S.; Niroula, M. R.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Park, S.; Pasyuk, E.; Pogorelko, O.; Price, J. W.; Protopopescu, D.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Sayre, D.; Schott, D.; Schumacher, R. A.; Seraydaryan, H.; Sharabian, Y. G.; Sober, D. I.; Sokhan, D.; Stepanyan, S.; Stepanyan, S. S.; Strauch, S.; Taiuti, M.; Tedeschi, D. J.; Tkachenko, S.; Ungaro, M.; Vineyard, M. F.; Wolin, E.; Wood, M. H.; Zhang, J.; Zhao, B.

    2009-06-01

    Beam-recoil transferred polarizations for the exclusive e→p→e'K+Λ→,Σ→0 reactions have been measured using the Continuous Electron Beam Accelerator Facility's large acceptance spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. New measurements have been completed at beam energies of 4.261 and 5.754 GeV that span a range of momentum transfer Q2 from 0.7 to 5.4 GeV2, invariant energy W from 1.6 to 2.6 GeV, and the full center-of-mass angular range of the K+ meson. These new data add to the existing CLAS K+Λ measurements at 2.567 GeV, and provide the first-ever data for the K+Σ0 channel in electroproduction. Comparisons of the data with several theoretical models are used to study the sensitivity to s-channel resonance contributions and the underlying reaction mechanism. Interpretations within two semiclassical partonic models are made to probe the underlying reaction mechanism and the s smacr quark-pair creation dynamics.

  1. [High frequency ultrasound].

    PubMed

    Sattler, E

    2015-07-01

    Diagnostic ultrasound has become a standard procedure in clinical dermatology. Devices with intermediate high frequencies of 7.5-15 MHz are used in dermato-oncology for the staging and postoperative care of skin tumor patients and in angiology for improved vessel diagnostics. In contrast, the high frequency ultrasound systems with 20-100 MHz probes offer a much higher resolution, yet with a lower penetration depth of about 1 cm. The main indications are the preoperative measurements of tumor thickness in malignant melanoma and other skin tumors and the assessment of inflammatory and soft tissue diseases, offering information on the course of these dermatoses and allowing therapy monitoring. This article gives an overview on technical principles, devices, mode of examination, influencing factors, interpretation of the images, indications but also limitations of this technique.

  2. High frequency reference electrode

    DOEpatents

    Kronberg, James W.

    1994-01-01

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or "halo" at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes.

  3. High frequency reference electrode

    DOEpatents

    Kronberg, J.W.

    1994-05-31

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or halo' at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes. 4 figs.

  4. ALMA High Frequency Techniques

    NASA Astrophysics Data System (ADS)

    Meyer, J. D.; Mason, B.; Impellizzeri, V.; Kameno, S.; Fomalont, E.; Chibueze, J.; Takahashi, S.; Remijan, A.; Wilson, C.; ALMA Science Team

    2015-12-01

    The purpose of the ALMA High Frequency Campaign is to improve the quality and efficiency of science observing in Bands 8, 9, and 10 (385-950 GHz), the highest frequencies available to the ALMA project. To this end, we outline observing modes which we have demonstrated to improve high frequency calibration for the 12m array and the ACA, and we present the calibration of the total power antennas at these frequencies. Band-to-band (B2B) transfer and bandwidth switching (BWSW), techniques which improve the speed and accuracy of calibration at the highest frequencies, are most necessary in Bands 8, 9, and 10 due to the rarity of strong calibrators. These techniques successfully enable increased signal-to-noise on the calibrator sources (and better calibration solutions) by measuring the calibrators at lower frequencies (B2B) or in wider bandwidths (BWSW) compared to the science target. We have also demonstrated the stability of the bandpass shape to better than 2.4% for 1 hour, hidden behind random noise, in Band 9. Finally, total power observing using the dual sideband receivers in Bands 9 and 10 requires the separation of the two sidebands; this procedure has been demonstrated in Band 9 and is undergoing further testing in Band 10.

  5. High Frequency EPR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Gatteschi, D.

    EPR has traditionally been used in order to obtain structural information on transition metal compounds, with exciting frequencies in the range 9-35 GHz.The recent availability of high magnetic field has prompted the use of higher frequencies. In this contribution the advantages of using High-Field-High-Frequency EPR (HF EPR) experiments are reviewed. After a brief introduction aiming to recall the fundamentals of EPR spectroscopy, a short description of the experimental apparatus needed to perform HF EPR measurements is provided. The remaining sections report selected examples showing how much information can be obtained by HF EPR spectra. They range from individual ions with integer spin to molecular clusters. Particular attention is devoted to the so called Single Molecule Magnets, SMM, i.e. to molecular clusters which show slow relaxation of the magnetization at low temperature. This effect is due to Ising type magnetic anisotropy which has been efficiently monitored through HF EPR s pectroscopy.

  6. FAST NEUTRON SPECTROMETER

    DOEpatents

    Davis, F.J.; Hurst, G.S.; Reinhardt, P.W.

    1959-08-18

    An improved proton recoil spectrometer for determining the energy spectrum of a fast neutron beam is described. Instead of discriminating against and thereby"throwing away" the many recoil protons other than those traveling parallel to the neutron beam axis as do conventional spectrometers, this device utilizes protons scattered over a very wide solid angle. An ovoidal gas-filled recoil chamber is coated on the inside with a scintillator. The ovoidal shape of the sensitive portion of the wall defining the chamber conforms to the envelope of the range of the proton recoils from the radiator disposed within the chamber. A photomultiplier monitors the output of the scintillator, and a counter counts the pulses caused by protons of energy just sufficient to reach the scintillator.

  7. High-frequency ECG

    NASA Technical Reports Server (NTRS)

    Tragardh, Elin; Schlegel, Todd T.

    2006-01-01

    The standard ECG is by convention limited to 0.05-150 Hz, but higher frequencies are also present in the ECG signal. With high-resolution technology, it is possible to record and analyze these higher frequencies. The highest amplitudes of the high-frequency components are found within the QRS complex. In past years, the term "high frequency", "high fidelity", and "wideband electrocardiography" have been used by several investigators to refer to the process of recording ECGs with an extended bandwidth of up to 1000 Hz. Several investigators have tried to analyze HF-QRS with the hope that additional features seen in the QRS complex would provide information enhancing the diagnostic value of the ECG. The development of computerized ECG-recording devices that made it possible to record ECG signals with high resolution in both time and amplitude, as well as better possibilities to store and process the signals digitally, offered new methods for analysis. Different techniques to extract the HF-QRS have been described. Several bandwidths and filter types have been applied for the extraction as well as different signal-averaging techniques for noise reduction. There is no standard method for acquiring and quantifying HF-QRS. The physiological mechanisms underlying HF-QRS are still not fully understood. One theory is that HF-QRS are related to the conduction velocity and the fragmentation of the depolarization wave in the myocardium. In a three-dimensional model of the ventricles with a fractal conduction system it was shown that high numbers of splitting branches are associated with HF-QRS. In this experiment, it was also shown that the changes seen in HF-QRS in patients with myocardial ischemia might be due to the slowing of the conduction velocity in the region of ischemia. This mechanism has been tested by Watanabe et al by infusing sodium channel blockers into the left anterior descending artery in dogs. In their study, 60 unipolar ECGs were recorded from the entire

  8. High acceptance recoil polarimeter

    SciTech Connect

    The HARP Collaboration

    1992-12-05

    In order to detect neutrons and protons in the 50 to 600 MeV energy range and measure their polarization, an efficient, low-noise, self-calibrating device is being designed. This detector, known as the High Acceptance Recoil Polarimeter (HARP), is based on the recoil principle of proton detection from np[r arrow]n[prime]p[prime] or pp[r arrow]p[prime]p[prime] scattering (detected particles are underlined) which intrinsically yields polarization information on the incoming particle. HARP will be commissioned to carry out experiments in 1994.

  9. Recoil polarization measurements

    NASA Astrophysics Data System (ADS)

    Brinkmann, Kai-Thomas

    2017-01-01

    Polarization observables in photon-induced meson production off nucleons have long been recognized to hold the promise of a detailed understanding of the excited states in the excitation spectrum of the nucleon. Photon beam and proton target polarization are routinely used at the ELSA facility in the Crystal Barrel/TAPS experiment and have yielded a wealth of data on contributing partial waves and nucleon resonances. A detector study on how to complement these ongoing studies by recoil polarization measurements that offer an orthogonal approach with otherwise unmeasurable observables in the field of non-strange meson photoproduction has been performed. Building on experience with silicon detectors operated in the photon beamline environment, first possible layouts of Si detector telescopes for recoil protons were developed. Various geometries, e.g. Archimedean spiral design of annular sensors, sector shapes and rectangular sensors were studied and have been used during test measurements. A prototype for the recoil polarimeter was built and subjected to performance tests in protonproton scattering at the COSY-accelerator in Jülich.

  10. Recoil Redsfhit with Coherence

    NASA Astrophysics Data System (ADS)

    Gallo, C. F.

    2009-05-01

    ``Recoil Redshift'' is due to the elastic interaction of photons/light with any individual electron, proton, ion, atom or molecule. This generalized Compton effect describes an individual photon-particle interaction where Energy, Linear Momentum and Angular Momentum are conserved, with NO change in the internal energy of the particle. Per Compton, the lost photon energy is zero in the forward photon propagation direction, and the energy loss increases with scattering angle. This is an INDIVIDUAL INcoherent process. To describe collective coherent effects, add/include Huygens forward reconstruction from multiple photon/particle redshifted scatterings. A coherent redshift will occur if the scattered photons' energies are WITHIN the initial linewidth. This yields an asymmetrically broadened redshifted line in the forward coherent direction with clear imaging properties. This is a coherent redshifted version of Rayleigh scattering which assumes identical non-redshifted photons. BUT the Compton Conservation energy-loss process must occur. The search for this small Recoil redshift is a good research project for ultra- precise ``frequency combs'' in gases (atomic and molecular), plasmas and combinations.

  11. Interpreting Recoil for Undergraduate Students

    ERIC Educational Resources Information Center

    Elsayed, Tarek A.

    2012-01-01

    The phenomenon of recoil is usually explained to students in the context of Newton's third law. Typically, when a projectile is fired, the recoil of the launch mechanism is interpreted as a reaction to the ejection of the smaller projectile. The same phenomenon is also interpreted in the context of the conservation of linear momentum, which is…

  12. Interpreting Recoil for Undergraduate Students

    ERIC Educational Resources Information Center

    Elsayed, Tarek A.

    2012-01-01

    The phenomenon of recoil is usually explained to students in the context of Newton's third law. Typically, when a projectile is fired, the recoil of the launch mechanism is interpreted as a reaction to the ejection of the smaller projectile. The same phenomenon is also interpreted in the context of the conservation of linear momentum, which is…

  13. [Principals of high frequency surgery].

    PubMed

    Bergler, W F; Hörmann, K; Hammerschmitt, N; Huber, K

    2004-10-01

    Electrosurgical instruments are routinely and daily applied at a variety of indications in Otorhinolaryngology. They can be used for cutting, coagulation and devitalisation. All have in common that the high frequency energy is transported into the tissue via an instrument and by this causes a thermal change. Depending on the duration and characteristic of the electricity a vaporisation of the tissue is effected through coagulation, devitalisation and carbonisation. The knowledge of the effects on the tissue by the choice of the different instrument parameters and application systems is essential for an ingenious therapeutically indication. In principal the following application methods for electrosurgery by modulation of the high frequency parameters are distinguished: the monopolar and the bipolar coagulation and devitalisation and the monopolar and the bipolar cutting. This article deals with the physical basis, the effects in the tissue as well as the single application methods of the high frequency surgery.

  14. Interpreting Recoil for Undergraduate Students

    NASA Astrophysics Data System (ADS)

    Elsayed, Tarek A.

    2012-04-01

    The phenomenon of recoil is usually explained to students in the context of Newton's third law. Typically, when a projectile is fired, the recoil of the launch mechanism is interpreted as a reaction to the ejection of the smaller projectile. The same phenomenon is also interpreted in the context of the conservation of linear momentum, which is closely related to Newton's third law. Since the actual microscopic causes of recoil differ from one problem to another, some students (and teachers) may not be satisfied with understanding recoil through the principles of conservation of linear momentum and Newton's third law. For these students, the origin of the recoil motion should be presented in more depth.

  15. Binaural beats at high frequencies.

    PubMed

    McFadden, D; Pasanen, E G

    1975-10-24

    Binaural beats have long been believed to be audible only at low frequencies, but an interaction reminiscent of a binaural beat can sometimes be heard when different two-tone complexes of high frequency are presented to the two ears. The primary requirement is that the frequency separation in the complex at one ear be slightly different from that in the other--that is, that there be a small interaural difference in the envelope periodicities. This finding is in accord with other recent demonstrations that the auditory system is not deaf to interaural time differences at high frequencies.

  16. High-frequency broadband transformers

    NASA Astrophysics Data System (ADS)

    London, S. E.; Tomashevich, S. V.

    1981-05-01

    A systematic review of the theory and design principles of high-frequency broadband transformers is presented. It is shown that the transformers of highest performance are those whose coils consist of strips of double-wire and multiwire transmission lines. Such devices are characterized by a wide operating frequency range, and make possible operation at microwave frequencies at high levels of transmitted power.

  17. High frequency integrated MOS filters

    NASA Technical Reports Server (NTRS)

    Peterson, C.

    1990-01-01

    Several techniques exist for implementing integrated MOS filters. These techniques fit into the general categories of sampled and tuned continuous-time filters. Advantages and limitations of each approach are discussed. This paper focuses primarily on the high frequency capabilities of MOS integrated filters.

  18. High-Frequency Channel Characterization

    DTIC Science & Technology

    2005-09-30

    High-Frequency Channel Characterization Michael B. Porter, Paul Hursky, Martin Siderius Heat , Light, and Sound Research, Inc. 12730 High...Physical Sciences (Bruce Abraham) • Arizona State University (Tolga Duman, Subhadeep Roy) • Heat , Light, and Sound Research, Inc.(M. Porter, A. Abawi, P...NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Heat , Light, and Sound Research, Inc,12730 High

  19. High frequency power distribution system

    NASA Technical Reports Server (NTRS)

    Patel, Mikund R.

    1986-01-01

    The objective of this project was to provide the technology of high frequency, high power transmission lines to the 100 kW power range at 20 kHz frequency. In addition to the necessary design studies, a 150 m long, 600 V, 60 A transmission line was built, tested and delivered for full vacuum tests. The configuration analysis on five alternative configurations resulted in the final selection of the three parallel Litz straps configuration, which gave a virtually concentric design in the electromagnetic sense. Low inductance, low EMI and flexibility in handling are the key features of this configuration. The final design was made after a parametric study to minimize the losses, weight and inductance. The construction of the cable was completed with no major difficulties. The R,L,C parameters measured on the cable agreed well with the calculated values. The corona tests on insulation samples showed a safety factor of 3.

  20. High frequency power distribution system

    NASA Astrophysics Data System (ADS)

    Patel, Mikund R.

    1986-04-01

    The objective of this project was to provide the technology of high frequency, high power transmission lines to the 100 kW power range at 20 kHz frequency. In addition to the necessary design studies, a 150 m long, 600 V, 60 A transmission line was built, tested and delivered for full vacuum tests. The configuration analysis on five alternative configurations resulted in the final selection of the three parallel Litz straps configuration, which gave a virtually concentric design in the electromagnetic sense. Low inductance, low EMI and flexibility in handling are the key features of this configuration. The final design was made after a parametric study to minimize the losses, weight and inductance. The construction of the cable was completed with no major difficulties. The R,L,C parameters measured on the cable agreed well with the calculated values. The corona tests on insulation samples showed a safety factor of 3.

  1. Recoil-decay tagging spectroscopy of 74162W88

    NASA Astrophysics Data System (ADS)

    Li, H. J.; Cederwall, B.; Bäck, T.; Qi, C.; Doncel, M.; Jakobsson, U.; Auranen, K.; Bönig, S.; Drummond, M. C.; Grahn, T.; Greenlees, P.; HerzáÅ, A.; Julin, R.; Juutinen, S.; Konki, J.; Kröll, T.; Leino, M.; McPeake, C.; O'Donnell, D.; Page, R. D.; Pakarinen, J.; Partanen, J.; Peura, P.; Rahkila, P.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Sayǧı, B.; Scholey, C.; Sorri, J.; Stolze, S.; Taylor, M. J.; Thornthwaite, A.; Uusitalo, J.; Xiao, Z. G.

    2015-07-01

    Excited states in the highly neutron-deficient nucleus 162W have been investigated via the 92Mo (78Kr,2α ) 162W reaction. Prompt γ rays were detected by the JUROGAM II high-purity germanium detector array and the recoiling fusion-evaporation products were separated by the recoil ion transport unit (RITU) gas-filled recoil separator and identified with the gamma recoil electron alpha tagging (GREAT) spectrometer at the focal plane of RITU. γ rays from 162W were identified uniquely using mother-daughter and mother-daughter-granddaughter α -decay correlations. The observation of a rotational-like ground-state band is interpreted within the framework of total Routhian surface (TRS) calculations, which suggest an axially symmetric ground-state shape with a γ -soft minimum at β2≈0.15 . Quasiparticle alignment effects are discussed based on cranked shell model calculations. New measurements of the 162W ground-state α -decay energy and half-life were also performed. The observed α -decay energy agrees with previous measurements. The half-life of 162W was determined to be t1 /2=990 (30 ) ms. This value deviates significantly from the currently adopted value of t1 /2=1360 (70 ) ms. In addition, the α -decay energy and half-life of 166Os were measured and found to agree with the adopted values.

  2. High Frequency Dynamic Nuclear Polarization

    PubMed Central

    Ni, Qing Zhe; Daviso, Eugenio; Can, Thach V.; Markhasin, Evgeny; Jawla, Sudheer K.; Swager, Timothy M.; Temkin, Richard J.; Herzfeld, Judith; Griffin, Robert G.

    2013-01-01

    Conspectus During the three decades 1980–2010, magic angle spinning (MAS) NMR developed into the method of choice to examine many chemical, physical and biological problems. In particular, a variety of dipolar recoupling methods to measure distances and torsion angles can now constrain molecular structures to high resolution. However, applications are often limited by the low sensitivity of the experiments, due in large part to the necessity of observing spectra of low-γ nuclei such as the I = ½ species 13C or 15N. The difficulty is still greater when quadrupolar nuclei, like 17O or 27Al, are involved. This problem has stimulated efforts to increase the sensitivity of MAS experiments. A particularly powerful approach is dynamic nuclear polarization (DNP) which takes advantage of the higher equilibrium polarization of electrons (which conventionally manifests in the great sensitivity advantage of EPR over NMR). In DNP, the sample is doped with a stable paramagnetic polarizing agent and irradiated with microwaves to transfer the high polarization in the electron spin reservoir to the nuclei of interest. The idea was first explored by Overhauser and Slichter in 1953. However, these experiments were carried out on static samples, at magnetic fields that are low by current standards. To be implemented in contemporary MAS NMR experiments, DNP requires microwave sources operating in the subterahertz regime — roughly 150–660 GHz — and cryogenic MAS probes. In addition, improvements were required in the polarizing agents, because the high concentrations of conventional radicals that are required to produce significant enhancements compromise spectral resolution. In the last two decades scientific and technical advances have addressed these problems and brought DNP to the point where it is achieving wide applicability. These advances include the development of high frequency gyrotron microwave sources operating in the subterahertz frequency range. In addition, low

  3. Amplifying High Frequency Acoustic Signals

    SciTech Connect

    Kunz, C

    2004-02-05

    In search of the hypothetical Higgs boson, a prototype electron accelerator structure has been developed for use in the Next Linear Collider (NLC), SLAC's proposed version of the machine necessary to create the predicted particle. The Next Linear Test Accelerator (NLCTA), designed to provide O.5GeV-lTeV center-of-mass collision energy, generates electromagnetic breakdowns inside its copper structure while the beam is running. The sparks vaporize the surface of the copper, and will eventually ruin the accelerator. They also create high-frequency (hf) acoustic signals (100 kHz-1 MHz). Acoustic sensors have been placed on the structure, however current knowledge regarding sound propagation in copper limits spark location to within one centimeter. A system was needed that simulates the sparks so further study of acoustic propagation can be pursued; the goal is locate them to within one millimeter. Various tests were done in order to identify an appropriate hf signal source, and to identify appropriate acoustic sensors to use. A high-voltage spark generator and the same sensors used on the actual structure proved most useful for the system. Two high-pass filters were also fabricated in order to measure signals that might be created above 2MHz. The 11-gain filter was used on the acoustic simulation system that was developed, and the 100-gain filter will be used on the NLCTA.

  4. High Frequency Linacs for Hadrontherapy

    NASA Astrophysics Data System (ADS)

    Amaldi, Ugo; Braccini, Saverio; Puggioni, Paolo

    The use of radiofrequency linacs for hadrontherapy was proposed about 20 years ago, but only recently has it been understood that the high repetition rate together with the possibility of very rapid energy variations offers an optimal solution to the present challenge of hadrontherapy: "paint" a moving tumor target in three dimensions with a pencil beam. Moreover, the fact that the energy, and thus the particle range, can be electronically adjusted implies that no absorber-based energy selection system is needed, which, in the case of cyclotron-based centers, is the cause of material activation. On the other side, a linac consumes less power than a synchrotron. The first part of this article describes the main advantages of high frequency linacs in hadrontherapy, the early design studies, and the construction and test of the first high-gradient prototype which accelerated protons. The second part illustrates some technical issues relevant to the design of copper standing wave accelerators, the present developments, and two designs of linac-based proton and carbon ion facilities. Superconductive linacs are not discussed, since nanoampere currents are sufficient for therapy. In the last two sections, a comparison with circular accelerators and an overview of future projects are presented.

  5. High-Frequency Inductor Materials

    NASA Astrophysics Data System (ADS)

    Varga, L. K.

    2014-01-01

    The Finemet-type nanocrystalline alloy represents an advanced soft-magnetic metal-metal-type nanocomposite with an eddy-current-determined high- frequency limit. A survey of different heat treatments under tensile stress is presented to tailor the hysteresis loop by induced transversal anisotropy. The flattened loop having reduced effective permeability enhances the eddy- current limit in the MHz region; For example, continuous stress annealing in a tubular furnace of 1 m length at 650°C, pulling the ribbon with a velocity of 4 m/min under a tensile stress of 200 MPa, results in a wound core having a permeability of 120 and a frequency limit of 10 MHz. Careful annealing preserves the static coercivity below 10 A/m. The power loss at 0.1 T and 100 kHz is only 82 mW/cm3, which is an order of magnitude lower then the values obtained for Sendust™ cores in similar conditions.

  6. Force optimized recoil control system

    NASA Astrophysics Data System (ADS)

    Townsend, P. E.; Radkiewicz, R. J.; Gartner, R. F.

    1982-05-01

    Reduction of the recoil force of high rate of fire automatic guns was proven effective. This system will allow consideration of more powerful guns for use in both helicopter and armored personnel carrier applications. By substituting the large shock loads of firing guns with a nearly constant force, both vibration and fatigue problems that prevent mounting of powerful automatic guns is eliminated.

  7. High frequency-heated air turbojet

    NASA Technical Reports Server (NTRS)

    Miron, J. H. D.

    1986-01-01

    A description is given of a method to heat air coming from a turbojet compressor to a temperature necessary to produce required expansion without requiring fuel. This is done by high frequency heating, which heats the walls corresponding to the combustion chamber in existing jets, by mounting high frequency coils in them. The current transformer and high frequency generator to be used are discussed.

  8. EMMA, the Proposed Recoil Separator for ISAC-II

    NASA Astrophysics Data System (ADS)

    Davids, Barry

    2004-10-01

    Design work has begun on EMMA, an electromagnetic mass analyzer for ISAC-II at TRIUMF. EMMA is a recoil mass spectrometer that will be used to separate the recoils of nuclear reactions from the beam, and to disperse them according to mass/charge. ISAC-II will provide intense, low-emittance beams of unstable nuclei with masses up to 150 u and maximum energies of at least 6.5 MeV/u. EMMA will be used in many different types of experiments with radioactive beams, especially those involving fusion-evaporation and transfer reactions. As such, it must be both efficient and selective, possessing large acceptances in angle, mass, and energy without sacrificing the necessary beam suppression and mass resolution.

  9. A gas ionisation detector in the axial (Bragg) geometry used for the time-of-flight elastic recoil detection analysis

    SciTech Connect

    Siketić, Zdravko; Skukan, Natko; Bogdanović Radović, Iva

    2015-08-15

    In this paper, time-of-flight elastic recoil detection analysis spectrometer with a newly constructed gas ionization detector for energy detection is presented. The detector is designed in the axial (Bragg) geometry with a 3 × 3 array of 50 nm thick Si{sub 3}N{sub 4} membranes as an entrance window. 40 mbar isobutane gas was sufficient to stop a 30 MeV primary iodine beam as well as all recoils in the detector volume. Spectrometer and detector performances were determined showing significant improvement in the mass and energy resolution, respectively, comparing to the spectrometer with a standard silicon particle detector for an energy measurement.

  10. A gas ionisation detector in the axial (Bragg) geometry used for the time-of-flight elastic recoil detection analysis.

    PubMed

    Siketić, Zdravko; Skukan, Natko; Bogdanović Radović, Iva

    2015-08-01

    In this paper, time-of-flight elastic recoil detection analysis spectrometer with a newly constructed gas ionization detector for energy detection is presented. The detector is designed in the axial (Bragg) geometry with a 3 × 3 array of 50 nm thick Si3N4 membranes as an entrance window. 40 mbar isobutane gas was sufficient to stop a 30 MeV primary iodine beam as well as all recoils in the detector volume. Spectrometer and detector performances were determined showing significant improvement in the mass and energy resolution, respectively, comparing to the spectrometer with a standard silicon particle detector for an energy measurement.

  11. High Frequency Chandler Wobble Excitation

    NASA Astrophysics Data System (ADS)

    Seitz, F.; Stuck, J.; Thomas, M.

    2003-04-01

    and OMCT forcing fields give no hint for increased excitation power in the Chandler band. Thus it is assumed, that continuous high frequency excitation due to stochastic weather phenomena is responsible for the perpetuation of the Chandler wobble.

  12. 75 FR 81284 - Nationwide Use of High Frequency and Ultra High Frequency Active SONAR Technology; Draft...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-27

    ... SECURITY Coast Guard Nationwide Use of High Frequency and Ultra High Frequency Active SONAR Technology... of High Frequency (HF) and Ultra High Frequency (UHF) Sound Navigation and Ranging (SONAR) Technology... less than a week; however, for environmental disasters such as the Deepwater Horizon oil spill,...

  13. High Frequency Radar Astronomy With HAARP

    DTIC Science & Technology

    2003-01-01

    a period of several years, the High frequency Active Auroral Research Program ( HAARP ) transmitting array near Gakona, Alaska , has increased in total...High Frequency Radar Astronomy With HAARP Paul Rodriguez Naval Research Laboratory Information Technology Division Washington, DC 20375, USA Edward...high frequency (HF) radar facility used for research purposes. The basic science objective of HAARP is to study nonlinear effects associated with

  14. The recoil proton polarization in. pi. p elastic scattering

    SciTech Connect

    Seftor, C.J.

    1988-09-01

    The polarization of the recoil proton for ..pi../sup +/p and ..pi../sup -/p elastic scattering has been measured for various angles at 547 MeV/c and 625 MeV/c by a collaboration involving The George Washington University; the University of California, Los Angeles; and Abilene Christian University. The experiment was performed at the P/sup 3/ East experimental area of the Los Alamos Meson Physics Facility. Beam intensities varied from 0.4 to 1.0 x 10/sup 7/ ..pi../sup -/'s/sec and from 3.0 to 10.0 x 10/sup 7/ ..pi../sup +/'s/sec. The beam spot size at the target was 1 cm in the horizontal direction by 2.5 cm in the vertical direction. A liquid-hydrogen target was used in a flask 5.7 cm in diameter and 10 cm high. The scattered pion and recoil proton were detected in coincidence using the Large Acceptance Spectrometer (LAS) to detect and momentum analyze the pions and the JANUS recoil proton polarimeter to detect and measure the polarization of the protons. Results from this experiment are compared with previous measurements of the polarization, with analyzing power data previously taken by this group, and to partial-wave analysis predictions. 12 refs., 53 figs., 18 tabs.

  15. Lightning protection devices for high frequencies equipments

    SciTech Connect

    Pierre, J.

    1983-01-01

    Contents: Mechanism of a Lightning Stroke from Antenna to Ground; Principles of Protection Devices for Feeders; Electrical Characteristics of H.F. Protection Devices; Calculation of H.F. Protection Devices; Catalogue Devices for High Frequency Protection; Some Measurement Results for Tees; Measurement Results for Decoupling Line Devices; Installation of High Frequency Devices.

  16. Prestin and high frequency hearing in mammals

    PubMed Central

    Zhang, Shuyi; Liu, Yang

    2011-01-01

    Recent evidence indicates that the evolution of ultrasonic hearing in echolocating bats and cetaceans has involved adaptive amino acid replacements in the cochlear gene prestin. A substantial number of these changes have occurred in parallel in both groups, suggesting that particular amino acid residues might confer greater auditory sensitivity to high frequencies. Here we review some of these findings, and consider whether similar signatures of prestin protein sequence evolution also occur in mammals that possess high frequency hearing for passive localization and conversely, whether this gene has undergone less change in mammals that lack high frequency hearing. PMID:21655450

  17. Propagation of high frequencies in Scandinavia

    SciTech Connect

    Bame, D.

    1989-04-01

    To determine if seismic signals at frequencies up to 50 Hz are useful for detecting events and discriminating between earthquakes and explosions, approximately 180 events from the three-component high-frequency seismic element (HFSE) installed at the center of the Norwegian Regional Seismic Array (NRSA) have been analyzed. The attenuation of high-frequency signals in Scandinavia varies with distance, azimuth, magnitude, and source effects. Most of the events were detected with HFSE, although detections were better on the NRSA where signal processing techniques were used. Based on a preliminary analysis, high-frequency data do not appear to be a useful discriminant in Scandinavia. 21 refs., 29 figs., 3 tabs.

  18. 78 FR 70567 - Nationwide Use of High Frequency and Ultra High Frequency Active SONAR Technology; Final...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-26

    ...] Nationwide Use of High Frequency and Ultra High Frequency Active SONAR Technology; Final Programmatic... Programmatic Environmental Assessment (PEA) for the Nationwide Use of High Frequency (HF) and Ultra High..., for environmental disasters such as the Deepwater Horizon oil spill, SONAR equipment could be used...

  19. High frequency testing of rubber mounts.

    PubMed

    Vahdati, Nader; Saunders, L Ken Lauderbaugh

    2002-04-01

    Rubber and fluid-filled rubber engine mounts are commonly used in automotive and aerospace applications to provide reduced cabin noise and vibration, and/or motion accommodations. In certain applications, the rubber mount may operate at frequencies as high as 5000 Hz. Therefore, dynamic stiffness of the mount needs to be known in this frequency range. Commercial high frequency test machines are practically nonexistent, and the best high frequency test machine on the market is only capable of frequencies as high as 1000 Hz. In this paper, a high frequency test machine is described that allows test engineers to study the high frequency performance of rubber mounts at frequencies up to 5000 Hz.

  20. Overview of the Advanced High Frequency Branch

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.

    2015-01-01

    This presentation provides an overview of the competencies, selected areas of research and technology development activities, and current external collaborative efforts of the NASA Glenn Research Center's Advanced High Frequency Branch.

  1. High power, high frequency component test facility

    NASA Technical Reports Server (NTRS)

    Roth, Mary Ellen; Krawczonek, Walter

    1990-01-01

    The NASA Lewis Research Center has available a high frequency, high power laboratory facility for testing various components of aerospace and/or terrestrial power systems. This facility is described here. All of its capabilities and potential applications are detailed.

  2. An introduction to high frequency radioteletype systems

    NASA Astrophysics Data System (ADS)

    Pinnau, Roger R.

    1989-10-01

    A basic introductory guide is provided to modern High Frequency (HF) data communications systems. Described are modern commercial radioteletype systems, data communication protocols, and various secrets of the trade.

  3. Neural coding of high-frequency tones

    NASA Technical Reports Server (NTRS)

    Howes, W. L.

    1976-01-01

    Available evidence was presented indicating that neural discharges in the auditory nerve display characteristic periodicities in response to any tonal stimulus including high-frequency stimuli, and that this periodicity corresponds to the subjective pitch.

  4. Real-time, high frequency QRS electrocardiograph

    NASA Technical Reports Server (NTRS)

    Schlegel, Todd T. (Inventor); DePalma, Jude L. (Inventor); Moradi, Saeed (Inventor)

    2006-01-01

    Real time cardiac electrical data are received from a patient, manipulated to determine various useful aspects of the ECG signal, and displayed in real time in a useful form on a computer screen or monitor. The monitor displays the high frequency data from the QRS complex in units of microvolts, juxtaposed with a display of conventional ECG data in units of millivolts or microvolts. The high frequency data are analyzed for their root mean square (RMS) voltage values and the discrete RMS values and related parameters are displayed in real time. The high frequency data from the QRS complex are analyzed with imbedded algorithms to determine the presence or absence of reduced amplitude zones, referred to herein as RAZs. RAZs are displayed as go, no-go signals on the computer monitor. The RMS and related values of the high frequency components are displayed as time varying signals, and the presence or absence of RAZs may be similarly displayed over time.

  5. Gas powered fluid gun with recoil mitigation

    DOEpatents

    Grubelich, Mark C.; Yonas, Gerold

    2017-01-03

    A gas powered fluid gun for propelling a stream or slug of a fluid at high velocity toward a target. Recoil mitigation is provided by a cavitating venturi that reduces or eliminates the associated recoil forces, with minimal or no backwash. By launching a quantity of water in the opposite direction, net momentum forces are reduced or eliminated.

  6. High-frequency conductivity of photoionized plasma

    SciTech Connect

    Anakhov, M. V.; Uryupin, S. A.

    2016-08-15

    The tensor of the high-frequency conductivity of a plasma created via tunnel ionization of atoms in the field of linearly or circularly polarized radiation is derived. It is shown that the real part of the conductivity tensor is highly anisotropic. In the case of a toroidal velocity distribution of photoelectrons, the possibility of amplification of a weak high-frequency field polarized at a sufficiently large angle to the anisotropy axis of the initial nonequilibrium distribution is revealed.

  7. Nuclear recoil measurements with the ARIS experiment

    NASA Astrophysics Data System (ADS)

    Fan, Alden; ARIS Collaboration

    2017-01-01

    As direct dark matter searches become increasingly sensitive, it is important to fully characterize the target of the search. The goal of the Argon Recoil Ionization and Scintillation (ARIS) experiment is to quantify information related to the scintillation and ionization energy scale, quenching factor, ion recombination probability, and scintillation time response of nuclear recoils, as expected from WIMPs, in liquid argon. A time projection chamber with an active mass of 0.5 kg of liquid argon and capable of full 3D position reconstruction was exposed to an inverse kinematic neutron beam at the Institut de Physique Nucleaire d'Orsay in France. A scan of nuclear recoil energies was performed through coincidence with a set of neutron detectors to quantify properties of nuclear recoils in liquid argon at various electric fields. The difference in ionization and scintillation response with differing recoil track angle to the electric field was also studied. The preliminary results of the experiment will be presented.

  8. 1987 calibration of the TFTR neutron spectrometers

    SciTech Connect

    Barnes, C.W.; Strachan, J.D.; Princeton Univ., NJ . Plasma Physics Lab.)

    1989-12-01

    The {sup 3}He neutron spectrometer used for measuring ion temperatures and the NE213 proton recoil spectrometer used for triton burnup measurements were absolutely calibrated with DT and DD neutron generators placed inside the TFTR vacuum vessel. The details of the detector response and calibration are presented. Comparisons are made to the neutron source strengths measured from other calibrated systems. 23 refs., 19 figs., 6 tabs.

  9. Gas powered fluid gun with recoil mitigation

    DOEpatents

    Grubelich, Mark C.; Yonas, Gerold

    2016-03-01

    A gas powered fluid gun for propelling a stream or slug of a fluid at high velocity toward a target. Recoil mitigation is provided that reduces or eliminates the associated recoil forces, with minimal or no backwash. By launching a quantity of water in the opposite direction, net momentum forces are reduced or eliminated. Examples of recoil mitigation devices include a cone for making a conical fluid sheet, a device forming multiple impinging streams of fluid, a cavitating venturi, one or more spinning vanes, or an annular tangential entry/exit.

  10. Gas powered fluid gun with recoil mitigation

    DOEpatents

    Grubelich, Mark C; Yonas, Gerold

    2013-11-12

    A gas powered fluid gun for propelling a stream or slug of a fluid at high velocity toward a target. Recoil mitigation is provided that reduces or eliminates the associated recoil forces, with minimal or no backwash. By launching a quantity of water in the opposite direction, net momentum forces are reduced or eliminated. Examples of recoil mitigation devices include a cone for making a conical fluid sheet, a device forming multiple impinging streams of fluid, a cavitating venturi, one or more spinning vanes, or an annular tangential entry/exit.

  11. A high frequency silicon pressure sensor

    NASA Technical Reports Server (NTRS)

    Kahng, S. K.; Gross, C.

    1980-01-01

    Theoretical and design considerations as well as fabrication and experimental work involved in the development of high-frequency silicon pressure sensors with an ultra-small diaphragm are discussed. A sensor is presented with a rectangular diaphragm of 0.0127 cm x 0.0254 cm x 1.06 micron; the sensor has a natural frequency of 625 kHz and a sensitivity of 0.82 mv/v-psi. High-frequency results from shock tube testing and low-frequency (less than 50 kHz) comparison with microphones are given.

  12. Metrology For High-Frequency Nanoelectronics

    SciTech Connect

    Wallis, T. Mitch; Imtiaz, Atif; Nembach, Hans T.; Rice, Paul; Kabos, Pavel

    2007-09-26

    Two metrological tools for high-frequency measurements of nanoscale systems are described: (i) two/N-port analysis of nanoscale devices as well as (ii) near-field scanning microwave microscopy (NSMM) for materials characterization. Calibrated two/N-port measurements were made on multiwalled carbon nanotubes (MWNT) welded to a coplanar waveguide. Significant changes in the extracted high-frequency electrical response of the welded MWNT were measured when the contacts to the MWNT were modified. Additionally, NSMM was used to characterize films of nanotube soot deposited on copper and sapphire substrates. The material properties of the films showed a strong dependence on the substrate material.

  13. Psychophysical tuning curves at very high frequencies

    NASA Astrophysics Data System (ADS)

    Yasin, Ifat; Plack, Christopher J.

    2005-10-01

    For most normal-hearing listeners, absolute thresholds increase rapidly above about 16 kHz. One hypothesis is that the high-frequency limit of the hearing-threshold curve is imposed by the transmission characteristics of the middle ear, which attenuates the sound input [Masterton et al., J. Acoust. Soc. Am. 45, 966-985 (1969)]. An alternative hypothesis is that the high-frequency limit of hearing is imposed by the tonotopicity of the cochlea [Ruggero and Temchin, Proc. Nat. Acad. Sci. U.S.A. 99, 13206-13210 (2002)]. The aim of this study was to test these hypotheses. Forward-masked psychophysical tuning curves (PTCs) were derived for signal frequencies of 12-17.5 kHz. For the highest signal frequencies, the high-frequency slopes of some PTCs were steeper than the slope of the hearing-threshold curve. The results also show that the human auditory system displays frequency selectivity for characteristic frequencies (CFs) as high as 17 kHz, above the frequency at which absolute thresholds begin to increase rapidly. The findings suggest that, for CFs up to 17 kHz, the high-frequency limitation in humans is imposed in part by the middle-ear attenuation, and not by the tonotopicity of the cochlea.

  14. Landau damping with high frequency impedance

    SciTech Connect

    Blaskiewicz,M.

    2009-05-04

    Coupled bunch longitudinal stability in the presence of high frequency impedances is considered. A frequency domain technique is developed and compared with simulations. The frequency domain technique allows for absolute stability tests and is applied to the problem of longitudinal stability in RHIC with the new 56 MHz RF system.

  15. Nuclear Recoil Identification in CDMS Experiment

    NASA Astrophysics Data System (ADS)

    Wang, Gensheng; Akerib, Dan

    2004-05-01

    The Cryogenic Dark Matter Search (CDMS) experiment achieves high sensitivity for WIMP dark matter particles recoiling from nuclei because of the rejection of predominant electromagnetic backgrounds. The measured charge energy and phonon energy ratio, or ionization yield, is a powerful tool for discrimination between nuclear recoil and electron recoil in CDMS experiment. However, since events occurring within a thin surface layer, notably low-energy background beta particles, suffer a loss in ionization charge collection, other method of surface--event rejection becomes important. I will describe the CDMS detector ionization measurement and ballistic phonon readout, with an emphasis on detector phenomenology. In particular, I will describe the primary CDMS detector quantities--ionization yield, phonon risetime, event location information and phonon energy partition distribution. The application of these parameters in nuclear recoil identification and in surface event rejection in CDMS experiment will be summarized.

  16. A Recoil-Beta Tagging Study of N = Z nucleus {sup 66}As

    SciTech Connect

    Ruotsalainen, P.; Scholey, C.; Greenlees, P. T.; Jakobsson, U.; Jones, P.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Nieminen, P.; Nyman, M.; Peura, P.; Rahkila, P.; Saren, J.; Sorri, J.; Uusitalo, J.; Wadsworth, R.; Jenkins, D. G.; Singh, B. S. Nara; Brock, T. S.

    2011-10-28

    A Recoil-Beta Tagging (RBT) experiment was recently performed at the accelerator laboratory at the University of Jyvaeskylae in order to identify T = 1 excited states in the medium-heavy N = Z = 33 nucleus {sup 66}As. The fusion-evaporation reaction {sup 28}Si({sup 40}Ca,pn){sup 66}As was employed at a beam energy of 75 MeV. The experiment was carried out utilising the JUROGAM II {gamma}-ray spectrometer in conjunction with the gas-filled recoil separator RITU and the GREAT focal plane spectrometer system. The half-lives and ordering of the two known isomeric states in {sup 66}As have been determined. In addition, several new prompt {gamma}-ray transitions from excited states both bypassing and decaying to the isomeric states in {sup 66}As have been observed.

  17. A Measurement of the Recoil Polarization of Electroproduced Λ(1116)

    SciTech Connect

    McAleer, Simeon B.

    2002-01-01

    The CEBAF Large Acceptance Spectrometer at the Thomas Jefferson National Laboratory was used to study the reaction e + p → e' + K+ + Λ(1116) for events where Λ(1116) subsequently decayed via the channel Λ(1116) → p + π-. Data were taken at incident electron beam energies of 2.5, 4.0, and 4.2 GeV during the 1999 E1C run period. They hyperon production spectra span the Q2 range from 0.5 to 2.8 GeV2 and nearly the entire range in the center of mass angles. The proton angular distribution in the Λ(1116) rest frame is used to deduce the recoil polarization of the hyperon, and the W and cos θ$K+\\atop{cm}$ dependence of the recoil polarization will be presented. The data show sizeable negative polarizations for the Λ(1116) as a function of both cos θ$K+\\atop{cm}$ and W.

  18. Neutrino-recoil induced desorption

    SciTech Connect

    Zhu, L.; Avci, R.; Lapeyre, G.J. ); Hindi, M.M.; Kozub, R.L.; Robinson, S.J. )

    1994-07-01

    Nuclear decay induced [sup 37]Cl ion desorption from the electron capture decay [sup 37]Ar[r arrow][sup 37]Cl+[nu] is reported for the first time. A mixture of one part [sup 36]Ar and [similar to]5[times]10[sup [minus]5] parts [sup 37]Ar ([sup 36/37]Ar) is physisorbed on a gold-plated Si wafer kept at 16 K under ultrahigh vacuum conditions. The time of flight (TOF) of recoiled [sup 37]Cl ions is measured using coincidence techniques. The observed kinetic energy distribution of the [sup 37]Cl ions is approximately Gaussian in shape, with a maximum at [approx]9.0 eV and a full width at half-maximum of [similar to]3 eV. Considering the binding energy of physisorbed [sup 37]Ar is [similar to]80 meV, the 9-eV peak energy compares well with that of the gas-phase value, where conservation of the energy and momentum fixes the kinetic energy of [sup 37]Cl ions at 9.54 eV. Using a combination of TOF and retarding field energy analysis, the charge states of detected ions for 1 ML (monolayer) of [sup 36/37]Ar are determined as 53%+1[ital e], 21%+2[ital e], and 26%+[ital ne], where [ital n][ge]3. The fraction of decaying [sup 37]Ar atoms which emerge from the surface as positive [sup 37]Cl ions is found to be 10%. Finally, a strong charge exchange reaction between a [sup 37]Cl ion and near-neighbor atoms causes a Coulomb explosion within the multilayers, increasing the kinetic energy of desorbing ions by as much as [similar to]7 eV.

  19. Turbulence in unsteady flow at high frequencies

    NASA Technical Reports Server (NTRS)

    Kuhn, Gary D.

    1990-01-01

    Turbulent flows subjected to oscillations of the mean flow were simulated using a large-eddy simulation computer code for flow in a channel. The objective of the simulations was to provide better understanding of the effects of time-dependent disturbances on the turbulence of a boundary layer and of the underlying physical phenomena regarding the basic interaction between the turbulence and external disturbances. The results confirmed that turbulence is sensitive to certain ranges of frequencies of disturbances. However, no direct connection was found between the frequency of imposed disturbances and the characteristic 'burst' frequency of turbulence. New insight into the nature of turbulence at high frequencies was found. Viscous phenomena near solid walls were found to be the dominant influence for high-frequency perturbations.

  20. Turbulence in unsteady flow at high frequencies

    NASA Technical Reports Server (NTRS)

    Kuhn, Gary D.

    1990-01-01

    Turbulent flows subjected to oscillations of the mean flow were simulated using a large-eddy simulation computer code for flow in a channel. The objective of the simulations was to provide better understanding of the effects of time-dependent disturbances on the turbulence of a boundary layer and of the underlying physical phenomena regarding the basic interaction between the turbulence and external disturbances. The results confirmed that turbulence is sensitive to certain ranges of frequencies of disturbances. However, no direct connection was found between the frequency of imposed disturbances and the characteristic 'burst' frequency of turbulence. New insight into the nature of turbulence at high frequencies was found. Viscous phenomena near solid walls were found to be the dominant influence for high-frequency perturbations.

  1. High frequency conductivity in carbon nanotubes

    SciTech Connect

    Abukari, S. S. Mensah, S. Y.; Twum, A.; Mensah, N. G.; Adu, K. A.; Rabiu, M.

    2012-12-15

    We report on theoretical analysis of high frequency conductivity in carbon nanotubes. Using the kinetic equation with constant relaxation time, an analytical expression for the complex conductivity is obtained. The real part of the complex conductivity is initially negative at zero frequency and become more negative with increasing frequency, until it reaches a resonance minimum at ω ∼ ω{sub B} for metallic zigzag CNs and ω < ω{sub B} for armchair CNs. This resonance enhancement is indicative for terahertz gain without the formation of current instabilities induced by negative dc conductivity. We noted that due to the high density of states of conduction electrons in metallic zigzag carbon nanotubes and the specific dispersion law inherent in hexagonal crystalline structure result in a uniquely high frequency conductivity than the corresponding values for metallic armchair carbon nanotubes. We suggest that this phenomenon can be used to suppress current instabilities that are normally associated with a negative dc differential conductivity.

  2. High-current, high-frequency capacitors

    NASA Astrophysics Data System (ADS)

    Renz, D. D.

    1983-06-01

    The NASA Lewis high-current, high-frequency capacitor development program was conducted under a contract with Maxwell Laboratories, Inc., San Diego, California. The program was started to develop power components for space power systems. One of the components lacking was a high-power, high-frequency capacitor. Some of the technology developed in this program may be directly usable in an all-electric airplane. The materials used in the capacitor included the following: the film is polypropylene, the impregnant is monoisopropyl biphenyl, the conductive epoxy is Emerson and Cuming Stycast 2850 KT, the foil is aluminum, the case is stainless steel (304), and the electrode is a modified copper-ceramic.

  3. High-current, high-frequency capacitors

    NASA Technical Reports Server (NTRS)

    Renz, D. D.

    1983-01-01

    The NASA Lewis high-current, high-frequency capacitor development program was conducted under a contract with Maxwell Laboratories, Inc., San Diego, California. The program was started to develop power components for space power systems. One of the components lacking was a high-power, high-frequency capacitor. Some of the technology developed in this program may be directly usable in an all-electric airplane. The materials used in the capacitor included the following: the film is polypropylene, the impregnant is monoisopropyl biphenyl, the conductive epoxy is Emerson and Cuming Stycast 2850 KT, the foil is aluminum, the case is stainless steel (304), and the electrode is a modified copper-ceramic.

  4. Apparatus for measuring high frequency currents

    NASA Technical Reports Server (NTRS)

    Hagmann, Mark J. (Inventor); Sutton, John F. (Inventor)

    2003-01-01

    An apparatus for measuring high frequency currents includes a non-ferrous core current probe that is coupled to a wide-band transimpedance amplifier. The current probe has a secondary winding with a winding resistance that is substantially smaller than the reactance of the winding. The sensitivity of the current probe is substantially flat over a wide band of frequencies. The apparatus is particularly useful for measuring exposure of humans to radio frequency currents.

  5. High Frequency Guided Wave Virtual Array SAFT

    NASA Astrophysics Data System (ADS)

    Roberts, R.; Pardini, A.; Diaz, A.

    2003-03-01

    The principles of the synthetic aperture focusing technique (SAFT) are generalized for application to high frequency plate wave signals. It is shown that a flaw signal received in long-range plate wave propagation can be analyzed as if the signals were measured by an infinite array of transducers in an unbounded medium. It is shown that SAFT-based flaw sizing can be performed with as few as three or less actual measurement positions.

  6. High-Frequency Percussive Ventilation Revisited

    DTIC Science & Technology

    2010-01-01

    physiologic and clin- ical outcomes. Pediatric and adult inhalational injury studies have linked HFPV to an improvement in static lung compliance...sedation–analgesic combinations (usually fentanyl with the individual or combined use of midazolam and propofol and/or dexmedetomidine), patient...1998;84:1174–7. 34. Frantz ID III, Close RH. Alveolar pressure swings during high frequency ventilation in rabbits. Pediatr Res 1985;19:162–6. 35. Pillow

  7. [High-frequency oscillatory ventilation in neonates].

    PubMed

    2002-09-01

    High-frequency oscillatory ventilation (HFOV) may be considered as an alternative in the management of severe neonatal respiratory failure requiring mechanical ventilation. In patients with diffuse pulmonary disease, HFOV can applied as a rescue therapy with a high lung volume strategy to obtain adequate alveolar recruitment. We review the mechanisms of gas exchange, as well as the indications, monitoring and special features of the use HVOF in the neonatal period.

  8. Extremely high frequency RF effects on electronics.

    SciTech Connect

    Loubriel, Guillermo Manuel; Vigliano, David; Coleman, Phillip Dale; Williams, Jeffery Thomas; Wouters, Gregg A.; Bacon, Larry Donald; Mar, Alan

    2012-01-01

    The objective of this work was to understand the fundamental physics of extremely high frequency RF effects on electronics. To accomplish this objective, we produced models, conducted simulations, and performed measurements to identify the mechanisms of effects as frequency increases into the millimeter-wave regime. Our purpose was to answer the questions, 'What are the tradeoffs between coupling, transmission losses, and device responses as frequency increases?', and, 'How high in frequency do effects on electronic systems continue to occur?' Using full wave electromagnetics codes and a transmission-line/circuit code, we investigated how extremely high-frequency RF propagates on wires and printed circuit board traces. We investigated both field-to-wire coupling and direct illumination of printed circuit boards to determine the significant mechanisms for inducing currents at device terminals. We measured coupling to wires and attenuation along wires for comparison to the simulations, looking at plane-wave coupling as it launches modes onto single and multiconductor structures. We simulated the response of discrete and integrated circuit semiconductor devices to those high-frequency currents and voltages, using SGFramework, the open-source General-purpose Semiconductor Simulator (gss), and Sandia's Charon semiconductor device physics codes. This report documents our findings.

  9. Ionospheric modifications in high frequency heating experiments

    SciTech Connect

    Kuo, Spencer P.

    2015-01-15

    Featured observations in high-frequency (HF) heating experiments conducted at Arecibo, EISCAT, and high frequency active auroral research program are discussed. These phenomena appearing in the F region of the ionosphere include high-frequency heater enhanced plasma lines, airglow enhancement, energetic electron flux, artificial ionization layers, artificial spread-F, ionization enhancement, artificial cusp, wideband absorption, short-scale (meters) density irregularities, and stimulated electromagnetic emissions, which were observed when the O-mode HF heater waves with frequencies below foF2 were applied. The implication and associated physical mechanism of each observation are discussed and explained. It is shown that these phenomena caused by the HF heating are all ascribed directly or indirectly to the excitation of parametric instabilities which instigate anomalous heating. Formulation and analysis of parametric instabilities are presented. The results show that oscillating two stream instability and parametric decay instability can be excited by the O-mode HF heater waves, transmitted from all three heating facilities, in the regions near the HF reflection height and near the upper hybrid resonance layer. The excited Langmuir waves, upper hybrid waves, ion acoustic waves, lower hybrid waves, and field-aligned density irregularities set off subsequent wave-wave and wave-electron interactions, giving rise to the observed phenomena.

  10. Ionospheric modifications in high frequency heating experiments

    NASA Astrophysics Data System (ADS)

    Kuo, Spencer P.

    2015-01-01

    Featured observations in high-frequency (HF) heating experiments conducted at Arecibo, EISCAT, and high frequency active auroral research program are discussed. These phenomena appearing in the F region of the ionosphere include high-frequency heater enhanced plasma lines, airglow enhancement, energetic electron flux, artificial ionization layers, artificial spread-F, ionization enhancement, artificial cusp, wideband absorption, short-scale (meters) density irregularities, and stimulated electromagnetic emissions, which were observed when the O-mode HF heater waves with frequencies below foF2 were applied. The implication and associated physical mechanism of each observation are discussed and explained. It is shown that these phenomena caused by the HF heating are all ascribed directly or indirectly to the excitation of parametric instabilities which instigate anomalous heating. Formulation and analysis of parametric instabilities are presented. The results show that oscillating two stream instability and parametric decay instability can be excited by the O-mode HF heater waves, transmitted from all three heating facilities, in the regions near the HF reflection height and near the upper hybrid resonance layer. The excited Langmuir waves, upper hybrid waves, ion acoustic waves, lower hybrid waves, and field-aligned density irregularities set off subsequent wave-wave and wave-electron interactions, giving rise to the observed phenomena.

  11. High frequency x-ray generator basics.

    PubMed

    Sobol, Wlad T

    2002-02-01

    The purpose of this paper is to present basic functional principles of high frequency x-ray generators. The emphasis is put on physical concepts that determine the engineering solutions to the problem of efficient generation and control of high voltage power required to drive the x-ray tube. The physics of magnetically coupled circuits is discussed first, as a background for the discussion of engineering issues related to high-frequency power transformer design. Attention is paid to physical processes that influence such factors as size, efficiency, and reliability of a high voltage power transformer. The basic electrical circuit of a high frequency generator is analyzed next, with focus on functional principles. This section investigates the role and function of basic components, such as power supply, inverter, and voltage doubler. Essential electronic circuits of generator control are then examined, including regulation of voltage, current and timing of electrical power delivery to the x-ray tube. Finally, issues related to efficient feedback control, including basic design of the AEC circuitry are reviewed.

  12. A Double Scattering Analytical Model For Elastic Recoil Detection Analysis

    SciTech Connect

    Barradas, N. P.; Lorenz, K.; Alves, E.; Darakchieva, V.

    2011-06-01

    We present an analytical model for calculation of double scattering in elastic recoil detection measurements. Only events involving the beam particle and the recoil are considered, i.e. 1) an ion scatters off a target element and then produces a recoil, and 2) an ion produces a recoil which then scatters off a target element. Events involving intermediate recoils are not considered, i.e. when the primary ion produces a recoil which then produces a second recoil. If the recoil element is also present in the stopping foil, recoil events in the stopping foil are also calculated. We included the model in the standard code for IBA data analysis NDF, and applied it to the measurement of hydrogen in Si.

  13. High-frequency Rayleigh-wave method

    USGS Publications Warehouse

    Xia, J.; Miller, R.D.; Xu, Y.; Luo, Y.; Chen, C.; Liu, J.; Ivanov, J.; Zeng, C.

    2009-01-01

    High-frequency (???2 Hz) Rayleigh-wave data acquired with a multichannel recording system have been utilized to determine shear (S)-wave velocities in near-surface geophysics since the early 1980s. This overview article discusses the main research results of high-frequency surface-wave techniques achieved by research groups at the Kansas Geological Survey and China University of Geosciences in the last 15 years. The multichannel analysis of surface wave (MASW) method is a non-invasive acoustic approach to estimate near-surface S-wave velocity. The differences between MASW results and direct borehole measurements are approximately 15% or less and random. Studies show that simultaneous inversion with higher modes and the fundamental mode can increase model resolution and an investigation depth. The other important seismic property, quality factor (Q), can also be estimated with the MASW method by inverting attenuation coefficients of Rayleigh waves. An inverted model (S-wave velocity or Q) obtained using a damped least-squares method can be assessed by an optimal damping vector in a vicinity of the inverted model determined by an objective function, which is the trace of a weighted sum of model-resolution and model-covariance matrices. Current developments include modeling high-frequency Rayleigh-waves in near-surface media, which builds a foundation for shallow seismic or Rayleigh-wave inversion in the time-offset domain; imaging dispersive energy with high resolution in the frequency-velocity domain and possibly with data in an arbitrary acquisition geometry, which opens a door for 3D surface-wave techniques; and successfully separating surface-wave modes, which provides a valuable tool to perform S-wave velocity profiling with high-horizontal resolution. ?? China University of Geosciences (Wuhan) and Springer-Verlag GmbH 2009.

  14. High frequency dynamic pressure calibration technique

    NASA Technical Reports Server (NTRS)

    Davis, P. A.; Zasimowich, R. F.

    1985-01-01

    A high frequency dynamic calibration technique for pressure transducers has been developed using a siren pressure generator (SPG). The SPG is an inlet-area-modulated device generating oscillating waveforms with dynamic pressure amplitudes up to 58.6 kPa (8.5 psi) in a frequency range of 1 to 10 kHz. A description of the generator, its operating characteristics and instrumentation used for pressure amplitude and frequency measurements is given. Waveform oscillographs and spectral analysis of the pressure transducers' output signals are presented.

  15. High frequency dynamic pressure calibration technique

    NASA Astrophysics Data System (ADS)

    Davis, P. A.; Zasimowich, R. F.

    A high frequency dynamic calibration technique for pressure transducers has been developed using a siren pressure generator (SPG). The SPG is an inlet-area-modulated device generating oscillating waveforms with dynamic pressure amplitudes up to 58.6 kPa (8.5 psi) in a frequency range of 1 to 10 kHz. A description of the generator, its operating characteristics and instrumentation used for pressure amplitude and frequency measurements is given. Waveform oscillographs and spectral analysis of the pressure transducers' output signals are presented.

  16. RF Breakdown in High Frequency Accelerators

    SciTech Connect

    Doebert, S

    2004-05-27

    RF breakdown in high-frequency accelerators appears to limit the maximum achievable gradient as well as the reliability of such devices. Experimental results from high power tests, obtained mostly in the framework of the NLC/GLC project at 11 GHz and from the CLIC study at 30 GHz, will be used to illustrate the important issues. The dependence of the breakdown phenomena on rf pulse length, operating frequency and fabrication material will be described. Since reliability is extremely important for large scale accelerators such as a linear collider, the measurements of breakdown rate as a function of the operating gradient will be highlighted.

  17. The LASI high-frequency ellipticity system

    SciTech Connect

    Sternberg, B.K.; Poulton, M.M.

    1995-12-31

    A high-frequency, high-resolution, electromagnetic (EM) imaging system has been developed for environmental geophysics surveys. Some key features of this system include: (1) rapid surveying to allow dense spatial sampling over a large area, (2) high-accuracy measurements which are used to produce a high-resolution image of the subsurface, (3) measurements which have excellent signal-to-noise ratio over a wide bandwidth (31 kHz to 32 MHz), (4) large-scale physical modeling to produce accurate theoretical responses over targets of interest in environmental geophysics surveys, (5) rapid neural network interpretation at the field site, and (6) visualization of complex structures during the survey.

  18. The LASI high-frequency ellipticity system

    SciTech Connect

    Sternberg, B.K.; Poulton, M.M.

    1995-10-01

    A high-frequency, high-resolution, electromagnetic (EM) imaging system has been developed for environmental geophysics surveys. Some key features of this system include: (1) rapid surveying to allow dense spatial sampling over a large area, (2) high-accuracy measurements which are used to produce a high-resolution image of the subsurface, (3) measurements which have excellent signal-to-noise ratio over a wide bandwidth (31 kHz to 32 MHz), (4) large-scale physical modeling to produce accurate theoretical responses over targets of interest in environmental geophysics surveys, (5) rapid neural network interpretation at the field site, and (6) visualization of complex structures during the survey.

  19. Inverter design for high frequency power distribution

    NASA Technical Reports Server (NTRS)

    King, R. J.

    1985-01-01

    A class of simple resonantly commutated inverters are investigated for use in a high power (100 KW - 1000 KW) high frequency (10 KHz - 20 KHz) AC power distribution system. The Mapham inverter is found to provide a unique combination of large thyristor turn-off angle and good utilization factor, much better than an alternate 'current-fed' inverter. The effects of loading the Mapham inverter entirely with rectifier loads are investigated by simulation and with an experimental 3 KW 20 KHz inverter. This inverter is found to be well suited to a power system with heavy rectifier loading.

  20. High frequency inductive lamp and power oscillator

    DOEpatents

    MacLennan, Donald A.; Dymond, Jr., Lauren E.; Gitsevich, Aleksandr; Grimm, William G.; Kipling, Kent; Kirkpatrick, Douglas A.; Ola, Samuel A.; Simpson, James E.; Trimble, William C.; Tsai, Peter; Turner, Brian P.

    2001-01-01

    A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and I or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to adjust the driving frequency of the oscillator.

  1. High frequency inductive lamp and power oscillator

    DOEpatents

    MacLennan, Donald A.; Turner, Brian P.; Dolan, James T.; Kirkpatrick, Douglas A.; Leng, Yongzhang

    2000-01-01

    A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and/or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to match the driving frequency of the oscillator to a plurality of tuning states of the lamp.

  2. High-Frequency Fluctuations During Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Jara-Almonte, J.; Ji, H.; Daughton, W. S.; Roytershteyn, V.; Yamada, M.; Yoo, J.; Fox, W. R., II

    2014-12-01

    During collisionless reconnection, the decoupling of the field from the plasma is known to occur only within the localized ion and electron diffusion regions, however predictions from fully kinetic simulations do not agree with experimental observations on the size of the electron diffusion region, implying differing reconnection mechanisms. Previous experiments, along with 2D and 3D simulations, have conclusively shown that this discrepancy cannot be explained by either classical collisions or Lower-Hybrid Drift Instability (Roytershtyn 2010, 2013). Due to computational limitations, however, previous simulations were constrained to have minimal scale separation between the electron skin depth and the Debye length (de/λD ~ 10), much smaller than in experiments (de/λD ~ 300). This lack of scale-separation can drastically modify the electrostatic microphysics within the diffusion layer. Using 3D, fully explicit kinetic simulations with a realistic and unprecedentedly large separation between the Debye length and the electron skin depth, de/λD = 64, we show that high frequency electrostatic waves (ω >> ωLH) can exist within the electron diffusion region. These waves generate small-scale turbulence within the electron diffusion region which acts to broaden the layer. Anomalous resistivity is also generated by the turbulence and significantly modifies the force balance. In addition to simulation results, initial experimental measurements of high frequency fluctuations (electrostatic and electromagnetic, f ≤ 1 GHz) in the Magnetic Reconnection Experiment (MRX) will be presented.

  3. High Frequency Plasma Generators for Ion Thrusters

    NASA Technical Reports Server (NTRS)

    Divergilio, W. F.; Goede, H.; Fosnight, V. V.

    1981-01-01

    The results of a one year program to experimentally adapt two new types of high frequency plasma generators to Argon ion thrusters and to analytically study a third high frequency source concept are presented. Conventional 30 cm two grid ion extraction was utilized or proposed for all three sources. The two plasma generating methods selected for experimental study were a radio frequency induction (RFI) source, operating at about 1 MHz, and an electron cyclotron heated (ECH) plasma source operating at about 5 GHz. Both sources utilize multi-linecusp permanent magnet configurations for plasma confinement. The plasma characteristics, plasma loading of the rf antenna, and the rf frequency dependence of source efficiency and antenna circuit efficiency are described for the RFI Multi-cusp source. In a series of tests of this source at Lewis Research Center, minimum discharge losses of 220+/-10 eV/ion were obtained with propellant utilization of .45 at a beam current of 3 amperes. Possible improvement modifications are discussed.

  4. High frequency ultrasonic scattering by biological tissues

    NASA Astrophysics Data System (ADS)

    Shung, K. Kirk; Maruvada, Subha

    2002-05-01

    High frequency (HF) diagnostic ultrasonic imaging devices at frequencies higher than 20 MHz have found applications in ophthalmology, dermatology, and vascular surgery. To be able to interpret these images and to further the development of these devices, a better understanding of ultrasonic scattering in biological tissues such as blood, liver, myocardium in the high frequency range is crucial. This work has previously been hampered by the lack of suitable transducers. With the availability of HF transducers going to 90 MHz, HF attenuation and backscatter experiments have been made on porcine red blood cell (RBC) suspensions, for which much data on attenuation and backscatter can be found in the literature in the lower frequency range for frequencies, from 30 to 90 MHz and on bovine tissues for frequencies from 10 to 30 MHz using a modified substitution method that allow the utilization of focused transducers. These results will be reviewed in this talk along with relevant theoretical models that could be applied to interpreting them. The relevance of the parameter that has been frequently used in the biomedical ultrasound literature to describe backscattering, the backscattering coefficient, will be critically examined.

  5. Protection circuitry for high frequency ultrasonic NDE

    NASA Astrophysics Data System (ADS)

    Chaggares, N. Chris; Tang, Raymond K.; Sinclair, A. N., Prof.; Foster, F. S., Prof.; Haraierciwz, Kasia; Starkoski, Brian

    2000-05-01

    Most commercial ultrasonic NDE equipment employs a voltage spike to stimulate a piezoelectric transducer. To protect the signal processing unit from damage from this spike, a voltage limiter or "diode clamp" is included in the pulser-receiver, and limits the voltage reaching the amplifier or oscilloscope. In this project, the deleterious effects of such limiters on the ultrasonic echo in the high frequency (50-100 MHz range) have been quantified: these effects include significant distortion in the frequency content, and oscillations causing a drop in timing resolution by over a factor of 2. To address these problems, a high-voltage high-frequency switch has been designed to replace the voltage limiter; the switch directs the high-voltage spike away from the signal processing/display unit, towards an impedance-matched termination. A prototype circuit has been built, based on two high-voltage MOSFET's acting as a switch for the bi-polar stimulation pulse. The reduction in echo distortion and improvement in time resolution have been successfully modeled with the CAD tool HSPICE, although parasitic capacitance in the current generation of commercial MOSFET's is a continuing concern.

  6. Noise temperature in graphene at high frequencies

    NASA Astrophysics Data System (ADS)

    Rengel, Raúl; Iglesias, José M.; Pascual, Elena; Martín, María J.

    2016-07-01

    A numerical method for obtaining the frequency-dependent noise temperature in monolayer graphene is presented. From the mobility and diffusion coefficient values provided by Monte Carlo simulation, the noise temperature in graphene is studied up to the THz range, considering also the influence of different substrate types. The influence of the applied electric field is investigated: the noise temperature is found to increase with the applied field, dropping down at high frequencies (in the sub-THz range). The results show that the low-frequency value of the noise temperature in graphene on a substrate tends to be reduced as compared to the case of suspended graphene due to the important effect of remote polar phonon interactions, thus indicating a reduced emitted noise power; however, at very high frequencies the influence of the substrate tends to be significantly reduced, and the differences between the suspended and on-substrate cases tend to be minimized. The values obtained are comparable to those observed in GaAs and semiconductor nitrides.

  7. Monolithic spectrometer

    DOEpatents

    Rajic, S.; Egert, C.M.; Kahl, W.K.; Snyder, W.B. Jr.; Evans, B.M. III; Marlar, T.A.; Cunningham, J.P.

    1998-05-19

    A monolithic spectrometer is disclosed for use in spectroscopy. The spectrometer is a single body of translucent material with positioned surfaces for the transmission, reflection and spectral analysis of light rays. 6 figs.

  8. Monolithic spectrometer

    DOEpatents

    Rajic, Slobodan; Egert, Charles M.; Kahl, William K.; Snyder, Jr., William B.; Evans, III, Boyd M.; Marlar, Troy A.; Cunningham, Joseph P.

    1998-01-01

    A monolithic spectrometer is disclosed for use in spectroscopy. The spectrometer is a single body of translucent material with positioned surfaces for the transmission, reflection and spectral analysis of light rays.

  9. Spectrometer technology recommendations

    NASA Astrophysics Data System (ADS)

    Wilson, William J.

    1988-08-01

    A typical heterodyne remote sensing system contains three major elements: the antenna, the radiometer, and the spectrometer. The radiometer consists of the local oscillator, the mixer, and the intermediate frequency amplifiers. This subsystem performs the function of down converting the high frequency incident thermal emission signal to a lower intermediate frequency. The spectrometer measures the power spectrum of the down-converted signal simultaneously in many contiguous frequency channels. Typical spectrum analysis requirements involve measurement of signal bandwidths of 100 to 1000 MHz with a channel resolution of 0.5 to 10 MHz. Three general approaches are used for spectrometers: (1) filter banks, (2) Acousto-Optic Spectrometers (AOS's), and (3) digital autocorrelators. In contrast to the two frequency domain techniques, an autocorrelator works in the time domain. The autocorrelation function (ACF) of the incoming signal is computed and averaged over the integration time. The averaged ACF is then Fourier transformed to obtain the signal power spectrum. Significant progress was made in the development of sub mm antennas and radiometers. It is now time to begin research in the development of low power spaceborne spectrometers and to reduce their size and weight. The near-term research goal will be to develop a prototype digital autocorrelation spectrometer, using VLSI gate array technology, which will have a small size, low power requirements, and can be used in spacecraft mm and sub mm radiometer systems. The long-range objective of this technology development is to make extremely low power, less than 10 mW/channel, small and stable wideband spectrometers which can be used in future mm and sub mm wavelength space missions such as the Large Deployable Reflector.

  10. Spectrometer technology recommendations

    NASA Technical Reports Server (NTRS)

    Wilson, William J.

    1988-01-01

    A typical heterodyne remote sensing system contains three major elements: the antenna, the radiometer, and the spectrometer. The radiometer consists of the local oscillator, the mixer, and the intermediate frequency amplifiers. This subsystem performs the function of down converting the high frequency incident thermal emission signal to a lower intermediate frequency. The spectrometer measures the power spectrum of the down-converted signal simultaneously in many contiguous frequency channels. Typical spectrum analysis requirements involve measurement of signal bandwidths of 100 to 1000 MHz with a channel resolution of 0.5 to 10 MHz. Three general approaches are used for spectrometers: (1) filter banks, (2) Acousto-Optic Spectrometers (AOS's), and (3) digital autocorrelators. In contrast to the two frequency domain techniques, an autocorrelator works in the time domain. The autocorrelation function (ACF) of the incoming signal is computed and averaged over the integration time. The averaged ACF is then Fourier transformed to obtain the signal power spectrum. Significant progress was made in the development of sub mm antennas and radiometers. It is now time to begin research in the development of low power spaceborne spectrometers and to reduce their size and weight. The near-term research goal will be to develop a prototype digital autocorrelation spectrometer, using VLSI gate array technology, which will have a small size, low power requirements, and can be used in spacecraft mm and sub mm radiometer systems. The long-range objective of this technology development is to make extremely low power, less than 10 mW/channel, small and stable wideband spectrometers which can be used in future mm and sub mm wavelength space missions such as the Large Deployable Reflector.

  11. Parametric nanomechanical amplification at very high frequency.

    PubMed

    Karabalin, R B; Feng, X L; Roukes, M L

    2009-09-01

    Parametric resonance and amplification are important in both fundamental physics and technological applications. Here we report very high frequency (VHF) parametric resonators and mechanical-domain amplifiers based on nanoelectromechanical systems (NEMS). Compound mechanical nanostructures patterned by multilayer, top-down nanofabrication are read out by a novel scheme that parametrically modulates longitudinal stress in doubly clamped beam NEMS resonators. Parametric pumping and signal amplification are demonstrated for VHF resonators up to approximately 130 MHz and provide useful enhancement of both resonance signal amplitude and quality factor. We find that Joule heating and reduced thermal conductance in these nanostructures ultimately impose an upper limit to device performance. We develop a theoretical model to account for both the parametric response and nonequilibrium thermal transport in these composite nanostructures. The results closely conform to our experimental observations, elucidate the frequency and threshold-voltage scaling in parametric VHF NEMS resonators and sensors, and establish the ultimate sensitivity limits of this approach.

  12. Degradation of PAHs by high frequency ultrasound.

    PubMed

    Manariotis, Ioannis D; Karapanagioti, Hrissi K; Chrysikopoulos, Constantinos V

    2011-04-01

    Polycyclic aromatic hydrocarbons (PAHs) are persistent organic compounds, which have been reported in the literature to efficiently degrade at low (e.g. 20 kHz) and moderate (e.g. 506 kHz) ultrasound frequencies. The present study focuses on degradation of naphthalene, phenanthrene, and pyrene by ultrasound at three different relatively high frequencies (i.e. 582, 862, and 1142 kHz). The experimental results indicate that for all three frequencies and power inputs ≥ 133 W phenanthrene degrades to concentrations lower than our experimental detection limit (<1 μg/L). Phenanthrene degrades significantly faster at 582 kHz than at 862 and 1142 kHz. For all three frequencies, the degradation rates per unit mass are similar for naphthalene and phenanthrene and lower for pyrene. Furthermore, naphthalene degradation requires less energy than phenanthrene, which requires less energy than pyrene under the same conditions. No hexane-extractable metabolites were identified in the solutions.

  13. Computer modeling of tactical high frequency antennas

    NASA Astrophysics Data System (ADS)

    Gregory, Bobby G., Jr.

    1992-06-01

    The purpose of this thesis was to compare the performance of three tactical high frequency antennas to be used as possible replacement for the Tactical Data Communications Central (TDCC) antennas. The antennas were modeled using the Numerical Electromagnetics Code, Version 3 (NEC3), and the Eyring Low Profile and Buried Antenna Modeling Program (PAT7) for several different frequencies and ground conditions. The performance was evaluated by comparing gain at the desired takeoff angles, the voltage standing wave ratio of each antenna, and its omni-directional capability. The buried antenna models, the ELPA-302 and horizontal dipole, were most effective when employed over poor ground conditions. The best performance under all conditions tested was demonstrated by the HT-20T. Each of these antennas have tactical advantages and disadvantages and can optimize communications under certain conditions. The selection of the best antenna is situation dependent. An experimental test of these models is recommended to verify the modeling results.

  14. High-frequency resonant-tunneling oscillators

    NASA Technical Reports Server (NTRS)

    Brown, E. R.; Parker, C. D.; Calawa, A. R.; Manfra, M. J.; Chen, C. L.

    1991-01-01

    Advances in high-frequency resonant-tunneling-diode (RTD) oscillators are described. Oscillations up to a frequency of 420 GHz have been achieved in the GaAs/AlAs system. Recent results obtained with In0.53Ga0.47As/AlAs and InAs/AlSb RTDs show a greatly increased power density and indicate the potential for fundamental oscillations up to about 1 THz. These results are consistent with a lumped-element equivalent circuit model of the RTD. The model shows that the maximum oscillation frequency of the GaAs/AlAs RTDs is limited primarily by series resistance, and that the power density is limited by low peak-to-valley current ratio.

  15. Plasma effects in high frequency radiative transfer

    SciTech Connect

    Alonso, C.T.

    1981-02-08

    This paper is intended as a survey of collective plasma processes which can affect the transfer of high frequency radiation in a hot dense plasma. We are rapidly approaching an era when this subject will become important in the laboratory. For pedagogical reasons we have chosen to examine plasma processes by relating them to a particular reference plasma which will consist of fully ionized carbon at a temperature kT=1 KeV (10/sup 70/K) and an electron density N = 3 x 10/sup 23/cm/sup -3/, (which corresponds to a mass density rho = 1 gm/cm/sup 3/ and an ion density N/sub i/ = 5 x 10/sup 22/ cm/sup -3/). We will consider the transport in such a plasma of photons ranging from 1 eV to 1 KeV in energy. Such photons will probably be frequently used as diagnostic probes of hot dense laboratory plasmas.

  16. High-frequency micromechanical columnar resonators

    PubMed Central

    Kehrbusch, Jenny; Ilin, Elena A; Bozek, Peter; Radzio, Bernhard; Oesterschulze, Egbert

    2009-01-01

    High-frequency silicon columnar microresonators are fabricated using a simple but effective technological scheme. An optimized fabrication scheme was invented to obtain mechanically protected microcolumns with lateral dimensions controlled on a scale of at least 1 μm. In this paper, we investigate the influence of the environmental conditions on the mechanical resonator properties. At ambient conditions, we observed a frequency stability δf/f of less than 10−6 during 5 h of operation at almost constant temperature. However, varying the temperature shifts the frequency by approximately −173 Hz °C− 1. In accordance with a viscous damping model of the ambient gas, we perceived that the quality factor of the first flexural mode decreased with the inverse of the square root of pressure. However, in the low-pressure regime, a linear dependence was observed. We also investigated the influence of the type of the immersing gas on the resonant frequency. PMID:27877296

  17. High-Frequency Mechanostimulation of Cell Adhesion.

    PubMed

    Kadem, Laith F; Suana, K Grace; Holz, Michelle; Wang, Wei; Westerhaus, Hannes; Herges, Rainer; Selhuber-Unkel, Christine

    2017-01-02

    Cell adhesion is regulated by molecularly defined protein interactions and by mechanical forces, which can activate a dynamic restructuring of adhesion sites. Previous attempts to explore the response of cell adhesion to forces have been limited to applying mechanical stimuli that involve the cytoskeleton. In contrast, we here apply a new, oscillatory type of stimulus through push-pull azobenzenes. Push-pull azobenzenes perform a high-frequency, molecular oscillation upon irradiation with visible light that has frequently been applied in polymer surface relief grating. We here use these oscillations to address single adhesion receptors. The effect of molecular oscillatory forces on cell adhesion has been analyzed using single-cell force spectroscopy and gene expression studies. Our experiments demonstrate a reinforcement of cell adhesion as well as upregulated expression levels of adhesion-associated genes as a result of the nanoscale "tickling" of integrins. This novel type of mechanical stimulus provides a previously unprecedented molecular control of cellular mechanosensing.

  18. High-frequency ultrasonic wire bonding systems

    PubMed

    Tsujino; Yoshihara; Sano; Ihara

    2000-03-01

    The vibration characteristics of longitudinal-complex transverse vibration systems with multiple resonance frequencies of 350-980 kHz for ultrasonic wire bonding of IC, LSI or electronic devices were studied. The complex vibration systems can be applied for direct welding of semiconductor tips (face-down bonding, flip-chip bonding) and packaging of electronic devices. A longitudinal-complex transverse vibration bonding system consists of a complex transverse vibration rod, two driving longitudinal transducers 7.0 mm in diameter and a transverse vibration welding tip. The vibration distributions along ceramic and stainless-steel welding tips were measured at up to 980 kHz. A high-frequency vibration system with a height of 20.7 mm and a weight of less than 15 g was obtained.

  19. Fundamentals of bipolar high-frequency surgery.

    PubMed

    Reidenbach, H D

    1993-04-01

    In endoscopic surgery a very precise surgical dissection technique and an efficient hemostasis are of decisive importance. The bipolar technique may be regarded as a method which satisfies both requirements, especially regarding a high safety standard in application. In this context the biophysical and technical fundamentals of this method, which have been known in principle for a long time, are described with regard to the special demands of a newly developed field of modern surgery. After classification of this method into a general and a quasi-bipolar mode, various technological solutions of specific bipolar probes, in a strict and in a generalized sense, are characterized in terms of indication. Experimental results obtained with different bipolar instruments and probes are given. The application of modern microprocessor-controlled high-frequency surgery equipment and, wherever necessary, the integration of additional ancillary technology into the specialized bipolar instruments may result in most useful and efficient tools of a key technology in endoscopic surgery.

  20. Proton recoil scintillator neutron rem meter

    DOEpatents

    Olsher, Richard H.; Seagraves, David T.

    2003-01-01

    A neutron rem meter utilizing proton recoil and thermal neutron scintillators to provide neutron detection and dose measurement. In using both fast scintillators and a thermal neutron scintillator the meter provides a wide range of sensitivity, uniform directional response, and uniform dose response. The scintillators output light to a photomultiplier tube that produces an electrical signal to an external neutron counter.

  1. Optical recoil of asymmetric nano-optical antenna.

    PubMed

    Song, Jung-Hwan; Shin, Jonghwa; Lim, Hee-Jin; Lee, Yong-Hee

    2011-08-01

    We propose nano-optical antennas with asymmetric radiation patterns as light-driven mechanical recoil force generators. Directional antennas are found to generate recoil force efficiently when driven in the spectral proximity of their resonances. It is also shown that the recoil force is equivalent to the Poynting vector integrated over a closed sphere containing the antenna structures.

  2. Time of flight elastic recoil detection analysis with a position sensitive detector

    SciTech Connect

    Siketic, Zdravko; Radovic, Iva Bogdanovic; Jaksic, Milko; Skukan, Natko

    2010-03-15

    A position sensitive detection system based on the microchannel plate detector has been constructed and installed at the existing time of flight (TOF) spectrometer in order to perform a kinematic correction and improve the surface time/depth resolution of elastic recoil detection analysis (ERDA) system. The position resolution of the detector has been tested for different types of ions and anode voltages. TOF spectra of recoiled O ions from SiO{sub 2} and F from CaF{sub 2} were collected in coincidence with position sensitive detector signal. Kinematic correction of TOF spectra improved surface time/depth resolution by {approx}20% for our system; however even higher improvements could be obtained in larger solid angle TOF-ERDA systems.

  3. Particle Spectrometers for FRIB

    NASA Astrophysics Data System (ADS)

    Amthor, A. M.

    2014-09-01

    FRIB promises to dramatically expand the variety of nuclear systems available for direct experimental study by providing rates of many rare isotopes orders of magnitude higher than those currently available. A new generation of experimental systems, including new particle spectrometers will be critical to our ability to take full advantage of the scientific opportunities offered by FRIB. The High-Rigidity Spectrometer (HRS) will allow for experiments with the most neutron-rich and short-lived isotopes produced by in-flight fragmentation at FRIB. The bending capability of the HRS (8 Tm) matches to the rigidity for which rare isotopes are produced at the highest intensity in the FRIB fragment separator. The experimental program will be focused on nuclear structure and astrophysics, and allow for the use of other cutting-edge detection systems for gamma, neutron, and charged-particle detection. Stopped and reaccelerated beam studies will be an important compliment to in-flight techniques at FRIB, providing world-unique, high quality, intense rare isotope beams at low energies up to and beyond the Coulomb barrier--with the completion of ReA12--and serving many of the science goals of the broader facility, from nuclear structure and astrophysics to applications. Two specialized recoil spectrometers are being developed for studies with reaccelerated beams. SECAR, the Separator for Capture Reactions, will be built following ReA3, coupled to a windowless gas jet target, JENSA, and will focus on radiative capture reactions for astrophysics, particularly those needed to improve our understanding of novae and X-ray bursts. A recoil separator following ReA12 is proposed to address a variety of physics cases based on fusion-evaporation, Coulomb excitation, transfer, and deep-inelastic reactions by providing a large angular, momentum and charge state acceptance; a high mass resolving power; and the flexibility to couple to a variety of auxiliary detector systems. Two designs

  4. Plant Responses to High Frequency Electromagnetic Fields

    PubMed Central

    Vian, Alain; Davies, Eric; Gendraud, Michel; Bonnet, Pierre

    2016-01-01

    High frequency nonionizing electromagnetic fields (HF-EMF) that are increasingly present in the environment constitute a genuine environmental stimulus able to evoke specific responses in plants that share many similarities with those observed after a stressful treatment. Plants constitute an outstanding model to study such interactions since their architecture (high surface area to volume ratio) optimizes their interaction with the environment. In the present review, after identifying the main exposure devices (transverse and gigahertz electromagnetic cells, wave guide, and mode stirred reverberating chamber) and general physics laws that govern EMF interactions with plants, we illustrate some of the observed responses after exposure to HF-EMF at the cellular, molecular, and whole plant scale. Indeed, numerous metabolic activities (reactive oxygen species metabolism, α- and β-amylase, Krebs cycle, pentose phosphate pathway, chlorophyll content, terpene emission, etc.) are modified, gene expression altered (calmodulin, calcium-dependent protein kinase, and proteinase inhibitor), and growth reduced (stem elongation and dry weight) after low power (i.e., nonthermal) HF-EMF exposure. These changes occur not only in the tissues directly exposed but also systemically in distant tissues. While the long-term impact of these metabolic changes remains largely unknown, we propose to consider nonionizing HF-EMF radiation as a noninjurious, genuine environmental factor that readily evokes changes in plant metabolism. PMID:26981524

  5. A High Frequency Model of Cascade Noise

    NASA Technical Reports Server (NTRS)

    Envia, Edmane

    1998-01-01

    Closed form asymptotic expressions for computing high frequency noise generated by an annular cascade in an infinite duct containing a uniform flow are presented. There are two new elements in this work. First, the annular duct mode representation does not rely on the often-used Bessel function expansion resulting in simpler expressions for both the radial eigenvalues and eigenfunctions of the duct. In particular, the new representation provides an explicit approximate formula for the radial eigenvalues obviating the need for solutions of the transcendental annular duct eigenvalue equation. Also, the radial eigenfunctions are represented in terms of exponentials eliminating the numerical problems associated with generating the Bessel functions on a computer. The second new element is the construction of an unsteady response model for an annular cascade. The new construction satisfies the boundary conditions on both the cascade and duct walls simultaneously adding a new level of realism to the noise calculations. Preliminary results which demonstrate the effectiveness of the new elements are presented. A discussion of the utility of the asymptotic formulas for calculating cascade discrete tone as well as broadband noise is also included.

  6. Extremely high-frequency therapy in oncology.

    PubMed

    Teppone, Mikhail; Avakyan, Romen

    2010-11-01

    This article represents a review of the literature, mainly from Russian sources, dealing with the therapeutic application of low-intensity electromagnetic radiation in the millimeter band applied to experimental and clinical oncology. At the early stage of these studies, efficacy and safety of millimeter electromagnetic radiation (extremely high frequency [EHF]) was proved for various types of malignant tumors. The majority of the further studies demonstrated the high efficacy and safety of millimeter wave radiation in treating patients suffering from both benign and malignant tumors. Developments led to treatment on skin melanoma, cancer of the ear-nose-throat, bowel and breast cancer, cancer of the uterus, lung, and stomach, solid tumors, as well as lymphoma. The main indications for this therapy are (1) preparation prior to radical treatment; (2) prevention and treatment of side-effects and complications from chemotherapy and radiotherapy; (3) prevention of metastases, relapses, and dissemination of the tumor; (4) treatment of the paraneoplastic syndrome; and (5) palliative therapy of incurable patients. In spite of the fact that not all mechanisms underlying effects of EHF therapy are known as yet, this therapeutic modality has been shown to have great potential in clinical oncology from studies performed in Eastern Europe and Russia.

  7. High frequency, high power capacitor development

    NASA Technical Reports Server (NTRS)

    White, C. W.; Hoffman, P. S.

    1983-01-01

    A program to develop a special high energy density, high power transfer capacitor to operate at frequency of 40 kHz, 600 V rms at 125 A rms plus 600 V dc bias for space operation. The program included material evaluation and selection, a capacitor design was prepared, a thermal analysis performed on the design. Fifty capacitors were manufactured for testing at 10 kHz and 40 kHz for 50 hours at Industrial Electric Heating Co. of Columbus, Ohio. The vacuum endurance test used on environmental chamber and temperature plate furnished by Maxwell. The capacitors were energized with a special power conditioning apparatus developed by Industrial Electric Heating Co. Temperature conditions of the capacitors were monitored by IEHCo test equipment. Successful completion of the vacuum endurance test series confirmed achievement of the main goal of producing a capacitor or reliable operation at high frequency in an environment normally not hospitable to electrical and electronic components. The capacitor developed compared to a typical commercial capacitor at the 40 kHz level represents a decrease in size and weight by a factor of seven.

  8. A high frequency electromagnetic impedance imaging system

    SciTech Connect

    Tseng, Hung-Wen; Lee, Ki Ha; Becker, Alex

    2003-01-15

    Non-invasive, high resolution geophysical mapping of the shallow subsurface is necessary for delineation of buried hazardous wastes, detecting unexploded ordinance, verifying and monitoring of containment or moisture contents, and other environmental applications. Electromagnetic (EM) techniques can be used for this purpose since electrical conductivity and dielectric permittivity are representative of the subsurface media. Measurements in the EM frequency band between 1 and 100 MHz are very important for such applications, because the induction number of many targets is small and the ability to determine the subsurface distribution of both electrical properties is required. Earlier workers were successful in developing systems for detecting anomalous areas, but quantitative interpretation of the data was difficult. Accurate measurements are necessary, but difficult to achieve for high-resolution imaging of the subsurface. We are developing a broadband non-invasive method for accurately mapping the electrical conductivity and dielectric permittivity of the shallow subsurface using an EM impedance approach similar to the MT exploration technique. Electric and magnetic sensors were tested to ensure that stray EM scattering is minimized and the quality of the data collected with the high-frequency impedance (HFI) system is good enough to allow high-resolution, multi-dimensional imaging of hidden targets. Additional efforts are being made to modify and further develop existing sensors and transmitters to improve the imaging capability and data acquisition efficiency.

  9. High-frequency plasma-heating apparatus

    DOEpatents

    Brambilla, Marco; Lallia, Pascal

    1978-01-01

    An array of adjacent wave guides feed high-frequency energy into a vacuum chamber in which a toroidal plasma is confined by a magnetic field, the wave guide array being located between two toroidal current windings. Waves are excited in the wave guide at a frequency substantially equal to the lower frequency hybrid wave of the plasma and a substantially equal phase shift is provided from one guide to the next between the waves therein. For plasmas of low peripheral density gradient, the guides are excited in the TE.sub.01 mode and the output electric field is parallel to the direction of the toroidal magnetic field. For exciting waves in plasmas of high peripheral density gradient, the guides are excited in the TM.sub.01 mode and the magnetic field at the wave guide outlets is parallel to the direction of the toroidal magnetic field. The wave excited at the outlet of the wave guide array is a progressive wave propagating in the direction opposite to that of the toroidal current and is, therefore, not absorbed by so-called "runaway" electrons.

  10. High frequency, high power capacitor development

    NASA Astrophysics Data System (ADS)

    White, C. W.; Hoffman, P. S.

    1983-03-01

    A program to develop a special high energy density, high power transfer capacitor to operate at frequency of 40 kHz, 600 V rms at 125 A rms plus 600 V dc bias for space operation. The program included material evaluation and selection, a capacitor design was prepared, a thermal analysis performed on the design. Fifty capacitors were manufactured for testing at 10 kHz and 40 kHz for 50 hours at Industrial Electric Heating Co. of Columbus, Ohio. The vacuum endurance test used on environmental chamber and temperature plate furnished by Maxwell. The capacitors were energized with a special power conditioning apparatus developed by Industrial Electric Heating Co. Temperature conditions of the capacitors were monitored by IEHCo test equipment. Successful completion of the vacuum endurance test series confirmed achievement of the main goal of producing a capacitor or reliable operation at high frequency in an environment normally not hospitable to electrical and electronic components. The capacitor developed compared to a typical commercial capacitor at the 40 kHz level represents a decrease in size and weight by a factor of seven.

  11. Aerodynamics of high frequency flapping wings

    NASA Astrophysics Data System (ADS)

    Hu, Zheng; Roll, Jesse; Cheng, Bo; Deng, Xinyan

    2010-11-01

    We investigated the aerodynamic performance of high frequency flapping wings using a 2.5 gram robotic insect mechanism developed in our lab. The mechanism flaps up to 65Hz with a pair of man-made wing mounted with 10cm wingtip-to-wingtip span. The mean aerodynamic lift force was measured by a lever platform, and the flow velocity and vorticity were measured using a stereo DPIV system in the frontal, parasagittal, and horizontal planes. Both near field (leading edge vortex) and far field flow (induced flow) were measured with instantaneous and phase-averaged results. Systematic experiments were performed on the man-made wings, cicada and hawk moth wings due to their similar size, frequency and Reynolds number. For insect wings, we used both dry and freshly-cut wings. The aerodynamic force increase with flapping frequency and the man-made wing generates more than 4 grams of lift at 35Hz with 3 volt input. Here we present the experimental results and the major differences in their aerodynamic performances.

  12. High-frequency graphene voltage amplifier.

    PubMed

    Han, Shu-Jen; Jenkins, Keith A; Valdes Garcia, Alberto; Franklin, Aaron D; Bol, Ageeth A; Haensch, Wilfried

    2011-09-14

    While graphene transistors have proven capable of delivering gigahertz-range cutoff frequencies, applying the devices to RF circuits has been largely hindered by the lack of current saturation in the zero band gap graphene. Herein, the first high-frequency voltage amplifier is demonstrated using large-area chemical vapor deposition grown graphene. The graphene field-effect transistor (GFET) has a 6-finger gate design with gate length of 500 nm. The graphene common-source amplifier exhibits ∼5 dB low frequency gain with the 3 dB bandwidth greater than 6 GHz. This first AC voltage gain demonstration of a GFET is attributed to the clear current saturation in the device, which is enabled by an ultrathin gate dielectric (4 nm HfO(2)) of the embedded gate structures. The device also shows extrinsic transconductance of 1.2 mS/μm at 1 V drain bias, the highest for graphene FETs using large-scale graphene reported to date.

  13. High-Frequency Observations of Blazars

    NASA Technical Reports Server (NTRS)

    Marscher, A. P.; Marchenko-Jorstad, S. G.; Mattox, J. R.; Wehrle, A. E.; Aller, M. F.

    2000-01-01

    We report on the results of high-frequency VLBA observations of 42 gamma-ray bright blazars monitored at 22 and 43 GHz between 1993.9 and 1997.6. In 1997 the observations included polarization-sensitive imaging. The cores of gamma-ray blazars are only weakly polarized, with EVPAs (electric-vector position angles) usually within 40 deg of the local direction of the jet. The EVPAs of the jet components are usually within 20 deg of the local jet direction. The apparent speeds of the gamma-ray bright blazars are considerably faster than in the general population of bright compact radio sources. Two X-ray flares (observed with RXTE) of the quasar PKS 1510-089 appear to be related to radio flares, but with the radio leading the X-ray variations by about 2 weeks. This can be explained either by synchrotron self-Compton emission in a component whose variations are limited by light travel time or by the Mirror Compton model.

  14. High-Frequency Observations of Blazars

    NASA Technical Reports Server (NTRS)

    Marscher, A. P.; Marchenko-Jorstad, S. G.; Mattox, J. R.; Wehrle, A. E.; Aller, M. F.

    2000-01-01

    We report on the results of high-frequency VLBA observations of 42 gamma ray bright blazars monitored at 22 and 43 GHz between 1993.9 and 1997-6. In 1997 the observations included polarization-sensitive imaging. The cores of gamma ray blazars are only weakly polarized, with EVPAs (electric-vector position angles) usually within 40 degrees of the local direction of the jet. The EVPAs of the jet components are usually within 20 degrees of the local jet direction. The apparent speeds of the gamma ray bright blazars are considerably faster than in the general population of bright compact radio sources. Two X-ray flares (observed with RXTE) of the quasar PKS 1510-089 appear to be related to radio flares, but with the radio leading the X-ray variations by about 2 weeks. This can be explained either by synchrotron self-Compton emission in a component whose variations are limited by light travel time or by the Mirror Compton model.

  15. High-Frequency Observations of Blazars

    NASA Technical Reports Server (NTRS)

    Marscher, A. P.; Marchenko-Jorstad, S. G.; Mattox, J. R.; Wehrle, A. E.; Aller, M. F.

    2000-01-01

    We report on the results of high-frequency VLBA observations of 42 gamma ray bright blazars monitored at 22 and 43 GHz between 1993.9 and 1997-6. In 1997 the observations included polarization-sensitive imaging. The cores of gamma ray blazars are only weakly polarized, with EVPAs (electric-vector position angles) usually within 40 degrees of the local direction of the jet. The EVPAs of the jet components are usually within 20 degrees of the local jet direction. The apparent speeds of the gamma ray bright blazars are considerably faster than in the general population of bright compact radio sources. Two X-ray flares (observed with RXTE) of the quasar PKS 1510-089 appear to be related to radio flares, but with the radio leading the X-ray variations by about 2 weeks. This can be explained either by synchrotron self-Compton emission in a component whose variations are limited by light travel time or by the Mirror Compton model.

  16. Recoil Based Fuel Breeding Fuel Structure

    SciTech Connect

    Popa-Simil, Liviu

    2008-07-01

    Nuclear transmutation reactions are based on the absorption of a smaller particle as neutron, proton, deuteron, alpha, etc. The resulting compound nucleus gets out of its initial lattice mainly by taking the recoil, also with help from its sudden change in chemical properties. The recoil implantation is used in correlation with thin and ultra thin materials mainly for producing radiopharmaceuticals and ultra-thin layer radioactive tracers. In nuclear reactors, the use of nano-particulate pellets could facilitate the recoil implantation for breeding, transmutation and partitioning purposes. Using enriched {sup 238}U or {sup 232}Th leads to {sup 239}Pu and {sup 233}U production while using other actinides as {sup 240}Pu, {sup 241}Am etc. leads to actinide burning. When such a lattice is immersed into a radiation resistant fluid (water, methanol, etc.), the recoiled product is transferred into the flowing fluid and removed from the hot area using a concentrator/purifier, preventing the occurrence of secondary transmutation reactions. The simulation of nuclear collision and energy transfer shows that the impacted nucleus recoils in the interstitial space creating a defect or lives small lattices. The defect diffuses, and if no recombination occurs it stops at the lattices boundaries. The nano-grains are coated in thin layer to get a hydrophilic shell to be washed by the collection liquid the particle is immersed in. The efficiency of collection depends on particle magnitude and nuclear reaction channel parameters. For {sup 239}Pu the direct recoil extraction rate is about 70% for {sup 238}UO{sub 2} grains of 5 nm diameters and is brought up to 95% by diffusion due to {sup 239}Neptunium incompatibility with Uranium dioxide lattice. Particles of 5 nm are hard to produce so a structure using particles of 100 nm have been tested. The particles were obtained by plasma sputtering in oxygen atmosphere. A novel effect as nano-cluster radiation damage robustness and cluster

  17. Correlation spectrometer

    DOEpatents

    Sinclair, Michael B [Albuquerque, NM; Pfeifer, Kent B [Los Lunas, NM; Flemming, Jeb H [Albuquerque, NM; Jones, Gary D [Tijeras, NM; Tigges, Chris P [Albuquerque, NM

    2010-04-13

    A correlation spectrometer can detect a large number of gaseous compounds, or chemical species, with a species-specific mask wheel. In this mode, the spectrometer is optimized for the direct measurement of individual target compounds. Additionally, the spectrometer can measure the transmission spectrum from a given sample of gas. In this mode, infrared light is passed through a gas sample and the infrared transmission signature of the gasses present is recorded and measured using Hadamard encoding techniques. The spectrometer can detect the transmission or emission spectra in any system where multiple species are present in a generally known volume.

  18. Cavity cooling below the recoil limit.

    PubMed

    Wolke, Matthias; Klinner, Julian; Keßler, Hans; Hemmerich, Andreas

    2012-07-06

    Conventional laser cooling relies on repeated electronic excitations by near-resonant light, which constrains its area of application to a selected number of atomic species prepared at moderate particle densities. Optical cavities with sufficiently large Purcell factors allow for laser cooling schemes, avoiding these limitations. Here, we report on an atom-cavity system, combining a Purcell factor above 40 with a cavity bandwidth below the recoil frequency associated with the kinetic energy transfer in a single photon scattering event. This lets us access a yet-unexplored regime of atom-cavity interactions, in which the atomic motion can be manipulated by targeted dissipation with sub-recoil resolution. We demonstrate cavity-induced heating of a Bose-Einstein condensate and subsequent cooling at particle densities and temperatures incompatible with conventional laser cooling.

  19. Skyrmion recoil in pion-nucleon scattering

    SciTech Connect

    Hughes, J. Physics Department, University of California at Davis, Davis, California 95616 ); Mathews, G.J. )

    1992-08-01

    We calculate the lowest-order recoil corrections to the pion-nucleon scattering matrix in the SU(2) Skyrme model. The corrections result from a direct semiclassical evaluation of path-integral expressions for relevant finite-time transition amplitudes. The {ital S} matrix for pion-nucleon scattering is extracted from these amplitudes by using a configuration-space representation for the asymptotic nucleons; the quanta are treated just as in the vacuum sector. The recoil corrections result from the Skyrmion freely translating between initial and final positions, and are relevant to a kinematical regime opposite to that where the impulse approximation is valid. The form of the corrections is model independent, unchanged for any chiral model with hedgehog solitary wave solutions. Remarkably, new lowest-lying resonances emerge in the {ital p} channels, whereas the {ital s} and {ital d} waves are not noticeably improved.

  20. Doping silicon with erbium by recoil implantation

    NASA Astrophysics Data System (ADS)

    Feklistov, K. V.; Abramkin, D. S.; Obodnikov, V. I.; Popov, V. P.

    2015-08-01

    In attempt to achieve strong surface doping of silicon with erbium, silicon was implanted with 250-keV argon ions through a thin erbium film deposited on the target surface. As a result, erbium recoil atoms were knocked out of the film and incorporated into the silicon substrate. In this way, silicon was doped with erbium atoms to a concentration of 5 × 1020 cm-3 within a depth slightly above 10 nm. For the formation of stable optically active ErO n complexes, oxygen recoil atoms were also incorporated into silicon. During the subsequent heat treatment, about half of the implanted erbium atoms segregated in the surface SiO2 layer. The main fraction of erbium retained in silicon after heat treatments is optically inactive.

  1. Polarization effects in recoil-induced resonances

    NASA Astrophysics Data System (ADS)

    Lazebnyi, D. B.; Brazhnikov, D. V.; Taichenachev, A. V.; Yudin, V. I.

    2017-01-01

    The effect of the field polarization on the amplitude of recoil-induced resonances (RIRs) is considered for laser-cooled free atoms and for atoms in a working magneto-optical trap (MOT). For all closed dipole transitions, explicit analytical expressions are obtained for the polarization dependence of the resonance amplitudes within a perturbation theory. Optimal polarization conditions are found for the observation of resonances.

  2. Multidimensional spectrometer

    SciTech Connect

    Zanni, Martin Thomas; Damrauer, Niels H.

    2010-07-20

    A multidimensional spectrometer for the infrared, visible, and ultraviolet regions of the electromagnetic spectrum, and a method for making multidimensional spectroscopic measurements in the infrared, visible, and ultraviolet regions of the electromagnetic spectrum. The multidimensional spectrometer facilitates measurements of inter- and intra-molecular interactions.

  3. High Frequency QRS ECG Accurately Detects Cardiomyopathy

    NASA Technical Reports Server (NTRS)

    Schlegel, Todd T.; Arenare, Brian; Poulin, Gregory; Moser, Daniel R.; Delgado, Reynolds

    2005-01-01

    High frequency (HF, 150-250 Hz) analysis over the entire QRS interval of the ECG is more sensitive than conventional ECG for detecting myocardial ischemia. However, the accuracy of HF QRS ECG for detecting cardiomyopathy is unknown. We obtained simultaneous resting conventional and HF QRS 12-lead ECGs in 66 patients with cardiomyopathy (EF = 23.2 plus or minus 6.l%, mean plus or minus SD) and in 66 age- and gender-matched healthy controls using PC-based ECG software recently developed at NASA. The single most accurate ECG parameter for detecting cardiomyopathy was an HF QRS morphological score that takes into consideration the total number and severity of reduced amplitude zones (RAZs) present plus the clustering of RAZs together in contiguous leads. This RAZ score had an area under the receiver operator curve (ROC) of 0.91, and was 88% sensitive, 82% specific and 85% accurate for identifying cardiomyopathy at optimum score cut-off of 140 points. Although conventional ECG parameters such as the QRS and QTc intervals were also significantly longer in patients than controls (P less than 0.001, BBBs excluded), these conventional parameters were less accurate (area under the ROC = 0.77 and 0.77, respectively) than HF QRS morphological parameters for identifying underlying cardiomyopathy. The total amplitude of the HF QRS complexes, as measured by summed root mean square voltages (RMSVs), also differed between patients and controls (33.8 plus or minus 11.5 vs. 41.5 plus or minus 13.6 mV, respectively, P less than 0.003), but this parameter was even less accurate in distinguishing the two groups (area under ROC = 0.67) than the HF QRS morphologic and conventional ECG parameters. Diagnostic accuracy was optimal (86%) when the RAZ score from the HF QRS ECG and the QTc interval from the conventional ECG were used simultaneously with cut-offs of greater than or equal to 40 points and greater than or equal to 445 ms, respectively. In conclusion 12-lead HF QRS ECG employing

  4. High Frequency QRS ECG Accurately Detects Cardiomyopathy

    NASA Technical Reports Server (NTRS)

    Schlegel, Todd T.; Arenare, Brian; Poulin, Gregory; Moser, Daniel R.; Delgado, Reynolds

    2005-01-01

    High frequency (HF, 150-250 Hz) analysis over the entire QRS interval of the ECG is more sensitive than conventional ECG for detecting myocardial ischemia. However, the accuracy of HF QRS ECG for detecting cardiomyopathy is unknown. We obtained simultaneous resting conventional and HF QRS 12-lead ECGs in 66 patients with cardiomyopathy (EF = 23.2 plus or minus 6.l%, mean plus or minus SD) and in 66 age- and gender-matched healthy controls using PC-based ECG software recently developed at NASA. The single most accurate ECG parameter for detecting cardiomyopathy was an HF QRS morphological score that takes into consideration the total number and severity of reduced amplitude zones (RAZs) present plus the clustering of RAZs together in contiguous leads. This RAZ score had an area under the receiver operator curve (ROC) of 0.91, and was 88% sensitive, 82% specific and 85% accurate for identifying cardiomyopathy at optimum score cut-off of 140 points. Although conventional ECG parameters such as the QRS and QTc intervals were also significantly longer in patients than controls (P less than 0.001, BBBs excluded), these conventional parameters were less accurate (area under the ROC = 0.77 and 0.77, respectively) than HF QRS morphological parameters for identifying underlying cardiomyopathy. The total amplitude of the HF QRS complexes, as measured by summed root mean square voltages (RMSVs), also differed between patients and controls (33.8 plus or minus 11.5 vs. 41.5 plus or minus 13.6 mV, respectively, P less than 0.003), but this parameter was even less accurate in distinguishing the two groups (area under ROC = 0.67) than the HF QRS morphologic and conventional ECG parameters. Diagnostic accuracy was optimal (86%) when the RAZ score from the HF QRS ECG and the QTc interval from the conventional ECG were used simultaneously with cut-offs of greater than or equal to 40 points and greater than or equal to 445 ms, respectively. In conclusion 12-lead HF QRS ECG employing

  5. Automation of experiments at the Dubna gas-filled separator of recoil nuclei: Part II

    NASA Astrophysics Data System (ADS)

    Tsyganov, Yu. S.

    2015-03-01

    An application developed in Builder C++ (Windows) for the offline analysis of experimental data from the spectrometer of the gas-filled separator of recoil nuclei (Flerov Laboratory of Nuclear Reactions) based on the double-sided silicon strip detector is discussed. The automatic express method developed for calibrating 48 strips of the silicon position-sensitive detector based on the three most energetic spectral lines from the natYb + 48Ca▭*Th reaction is compared to the results produced by more rigorous calibration methods. The examples of spectra for this reaction and the results of filtering for the proposed calibration algorithm are given.

  6. Measurement of Low Energy Electronic Recoil Response and Electronic/Nuclear Recoils Discrimination in XENON100

    NASA Astrophysics Data System (ADS)

    Ye, Jingqiang; Xenon Collaboration

    2017-01-01

    The XENON100 detector uses liquid xenon time projection chamber to search for nuclear recoils(NR) caused by hypothetical Weakly Interacting Massive Particles (WIMPs). The backgrounds are mostly electronic recoils(ER), thus it's crucial to distinguish NR from ER. Using high statistical calibration data from tritiated methane, AmBe and other sources in XENON100, the ER/NR discrimination under different electric fields are measured. The Photon yield and recombination fluctuation of low energy electronic recoils under different fields will also be presented and compared to results from NEST and other experiments, which is crucial to understanding the response of liquid xenon detectors in the energy regime of searching dark matter.

  7. Bulk and integrated acousto-optic spectrometers for molecular astronomy with heterodyne spectrometers

    NASA Technical Reports Server (NTRS)

    Chin, G.; Buhl, D.; Florez, J. M.

    1981-01-01

    A survey of acousto-optic spectrometers for molecular astronomy is presented, noting a technique of combining the acoustic bending of a collimated coherent light beam with a Bragg cell followed by an array of sensitive photodetectors. This acousto-optic spectrometer has a large bandwidth, a large number of channels, high resolution, and is energy efficient. Receiver development has concentrated on high-frequency heterodyne systems for the study of the chemical composition of the interstellar medium. RF spectrometers employing acousto-optic diffraction cells are described. Acousto-optic techniques have been suggested for applications to electronic warfare, electronic countermeasures and electronic support systems. Plans to use integrated optics for the further miniaturization of acousto-optic spectrometers are described. Bulk acousto-optic spectrometers with 300 MHz and 1 GHz bandwidths are being developed for use in the back-end of high-frequency heterodyne receivers for astronomical research.

  8. Bulk and integrated acousto-optic spectrometers for molecular astronomy with heterodyne spectrometers

    NASA Technical Reports Server (NTRS)

    Chin, G.; Buhl, D.; Florez, J. M.

    1981-01-01

    A survey of acousto-optic spectrometers for molecular astronomy is presented, noting a technique of combining the acoustic bending of a collimated coherent light beam with a Bragg cell followed by an array of sensitive photodetectors. This acousto-optic spectrometer has a large bandwidth, a large number of channels, high resolution, and is energy efficient. Receiver development has concentrated on high-frequency heterodyne systems for the study of the chemical composition of the interstellar medium. RF spectrometers employing acousto-optic diffraction cells are described. Acousto-optic techniques have been suggested for applications to electronic warfare, electronic countermeasures and electronic support systems. Plans to use integrated optics for the further miniaturization of acousto-optic spectrometers are described. Bulk acousto-optic spectrometers with 300 MHz and 1 GHz bandwidths are being developed for use in the back-end of high-frequency heterodyne receivers for astronomical research.

  9. 140 GHz pulsed Fourier transform microwave spectrometer

    DOEpatents

    Kolbe, W.F.; Leskovar, B.

    1985-07-29

    A high frequency energy pulsing system suitable for use in a pulsed microwave spectrometer, including means for generating a high frequency carrier signal, and means for generating a low frequency modulating signal. The carrier signal is continuously fed to a modulator and the modulating signal is fed through a pulse switch to the modulator. When the pulse switch is on, the modulator will produce sideband signals above and below the carrier signal frequency. A frequency-responsive device is tuned to one of the sideband signals and sway from the carrier frequency so that the high frequency energization of the frequency-responsive device is controlled by the pulse switch.

  10. Variable Coupling Scheme for High Frequency Electron Spin Resonance Resonators Using Asymmetric Meshes.

    PubMed

    Tipikin, D S; Earle, K A; Freed, J H

    2010-01-01

    The sensitivity of a high frequency electron spin resonance (ESR) spectrometer depends strongly on the structure used to couple the incident millimeter wave to the sample that generates the ESR signal. Subsequent coupling of the ESR signal to the detection arm of the spectrometer is also a crucial consideration for achieving high spectrometer sensitivity. In previous work, we found that a means for continuously varying the coupling was necessary for attaining high sensitivity reliably and reproducibly. We report here on a novel asymmetric mesh structure that achieves continuously variable coupling by rotating the mesh in its own plane about the millimeter wave transmission line optical axis. We quantify the performance of this device with nitroxide spin-label spectra in both a lossy aqueous solution and a low loss solid state system. These two systems have very different coupling requirements and are representative of the range of coupling achievable with this technique. Lossy systems in particular are a demanding test of the achievable sensitivity and allow us to assess the suitability of this approach for applying high frequency ESR to the study of biological systems at physiological conditions, for example. The variable coupling technique reported on here allows us to readily achieve a factor of ca. 7 improvement in signal to noise at 170 GHz and a factor of ca. 5 at 95 GHz over what has previously been reported for lossy samples.

  11. Schwarzschild spectrometer.

    PubMed

    Mouriz, M Dolores; Lago, Elena López; Prieto-Blanco, Xesús; González-Núñez, Héctor; de la Fuente, Raúl

    2011-06-01

    This is a proposal and description of a new spectrometer based on the Schwarzschild optical system. The proposed design contains two Schwarzschild optical systems. Light diverging from the spectrometer entrance slit is collimated by the first one; the collimated light beam hits a planar diffraction grating and the light dispersed from the grating is focused by the second system, which is concentric with the first. A very simple procedure obtains designs that are anastigmatic for the center of the slit and for a particular wavelength. A specific example shows the performance of this type of spectrometer.

  12. Effects of interelectrode gap on high frequency and very high frequency capacitively coupled plasmas

    SciTech Connect

    Bera, Kallol; Rauf, Shahid; Ramaswamy, Kartik; Collins, Ken

    2009-07-15

    Capacitively coupled plasma (CCP) discharges using high frequency (HF) and very high frequency (VHF) sources are widely used for dielectric etching in the semiconductor industry. A two-dimensional fluid plasma model is used to investigate the effects of interelectrode gap on plasma spatial characteristics of both HF and VHF CCPs. The plasma model includes the full set of Maxwell's equations in their potential formulation. The peak in plasma density is close to the electrode edge at 13.5 MHz for a small interelectrode gap. This is due to electric field enhancement at the electrode edge. As the gap is increased, the plasma produced at the electrode edge diffuses to the chamber center and the plasma becomes more uniform. At 180 MHz, where electromagnetic standing wave effects are strong, the plasma density peaks at the chamber center at large interelectrode gap. As the interelectrode gap is decreased, the electron density increases near the electrode edge due to inductive heating and electrostatic electron heating, which makes the plasma more uniform in the interelectrode region.

  13. SCINTILLATION SPECTROMETER

    DOEpatents

    Bell, P.R.; Francis, J.E.

    1960-06-21

    A portable scintillation spectrometer is described which is especially useful in radio-biological studies for determining the uptake and distribution of gamma -emitting substances in tissue. The spectrometer includes a collimator having a plurality of apertures that are hexagonal in cross section. Two crystals are provided: one is activated to respond to incident rays from the collimator; the other is not activated and shields the first from external radiation.

  14. 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

  15. High-frequency Probing Diagnostic for Hall Current Plasma Thrusters

    SciTech Connect

    A.A. Litvak; Y. Raitses; N.J. Fisch

    2001-10-25

    High-frequency oscillations (1-100 MHz) in Hall thrusters have apparently eluded significant experimental scrutiny. A diagnostic setup, consisting of a single Langmuir probe, a special shielded probe connector-positioner, and an electronic impedance-matching circuit, was successfully built and calibrated. Through simultaneous high-frequency probing of the Hall thruster plasma at multiple locations, high-frequency plasma waves have been identified and characterized for various thruster operating conditions.

  16. On-clip high frequency reliability and failure test structures

    DOEpatents

    Snyder, E.S.; Campbell, D.V.

    1997-04-29

    Self-stressing test structures for realistic high frequency reliability characterizations. An on-chip high frequency oscillator, controlled by DC signals from off-chip, provides a range of high frequency pulses to test structures. The test structures provide information with regard to a variety of reliability failure mechanisms, including hot-carriers, electromigration, and oxide breakdown. The system is normally integrated at the wafer level to predict the failure mechanisms of the production integrated circuits on the same wafer. 22 figs.

  17. On-clip high frequency reliability and failure test structures

    DOEpatents

    Snyder, Eric S.; Campbell, David V.

    1997-01-01

    Self-stressing test structures for realistic high frequency reliability characterizations. An on-chip high frequency oscillator, controlled by DC signals from off-chip, provides a range of high frequency pulses to test structures. The test structures provide information with regard to a variety of reliability failure mechanisms, including hot-carriers, electromigration, and oxide breakdown. The system is normally integrated at the wafer level to predict the failure mechanisms of the production integrated circuits on the same wafer.

  18. Thermal recoil force, telemetry, and the Pioneer anomaly

    SciTech Connect

    Toth, Viktor T.; Turyshev, Slava G.

    2009-02-15

    Precision navigation of spacecraft requires accurate knowledge of small forces, including the recoil force due to anisotropies of thermal radiation emitted by spacecraft systems. We develop a formalism to derive the thermal recoil force from the basic principles of radiative heat exchange and energy-momentum conservation. The thermal power emitted by the spacecraft can be computed from engineering data obtained from flight telemetry, which yields a practical approach to incorporate the thermal recoil force into precision spacecraft navigation. Alternatively, orbit determination can be used to estimate the contribution of the thermal recoil force. We apply this approach to the Pioneer anomaly using a simulated Pioneer 10 Doppler data set.

  19. Neutron electric form factor via recoil polarimetry

    SciTech Connect

    Madey, Richard; Semenov, Andrei; Taylor, Simon; Aghalaryan, Aram; Crouse, Erick; MacLachlan, Glen; Plaster, Bradley; Tajima, Shigeyuki; Tireman, William; Yan, Chenyu; Ahmidouch, Abdellah; Anderson, Brian; Asaturyan, Razmik; Baker, O; Baldwin, Alan; Breuer, Herbert; Carlini, Roger; Christy, Michael; Churchwell, Steve; Cole, Leon; Danagoulian, Samuel; Day, Donal; Elaasar, Mostafa; Ent, Rolf; Farkhondeh, Manouchehr; Fenker, Howard; Finn, John; Gan, Liping; Garrow, Kenneth; Gueye, Paul; Howell, Calvin; Hu, Bitao; Jones, Mark; Kelly, James; Keppel, Cynthia; Khandaker, Mahbubul; Kim, Wooyoung; Kowalski, Stanley; Lung, Allison; Mack, David; Manley, D; Markowitz, Pete; Mitchell, Joseph; Mkrtchyan, Hamlet; Opper, Allena; Perdrisat, Charles; Punjabi, Vina; Raue, Brian; Reichelt, Tilmann; Reinhold, Joerg; Roche, Julie; Sato, Yoshinori; Seo, Wonick; Simicevic, Neven; Smith, Gregory; Stepanyan, Samuel; Tadevosyan, Vardan; Tang, Liguang; Ulmer, Paul; Vulcan, William; Watson, John; Wells, Steven; Wesselmann, Frank; Wood, Stephen; Yan, Chen; Yang, Seunghoon; Yuan, Lulin; Zhang, Wei-Ming; Zhu, Hong Guo; Zhu, Xiaofeng

    2003-05-01

    The ratio of the electric to the magnetic form factor of the neutron, G_En/G_Mn, was measured via recoil polarimetry from the quasielastic d({pol-e},e'{pol-n)p reaction at three values of Q^2 [viz., 0.45, 1.15 and 1.47 (GeV/c)^2] in Hall C of the Thomas Jefferson National Accelerator Facility. Preliminary data indicate that G_En follows the Galster parameterization up to Q^2 = 1.15 (GeV/c)^2 and appears to rise above the Galster parameterization at Q^2 = 1.47 (GeV/c)^2.

  20. Recoil Considerations for Shoulder-Fired Weapons

    DTIC Science & Technology

    2012-05-01

    2012) Steyr 15.2 mm 35 g 1450 m/s 39.6 lb 11.4 Burns (2012) Type 97 (Japanese) 20 mm 162 g 790 m/s 130 lb 28.7 Burns (2012) 12HB00 ( Remington ...shotgun 0.727 in 807 gr (12 × 00) 1225 ft/s 7.0 lb 4.37 Remington (2011) Remington Express 12B0 shotgun 0.727 in 580 gr (12 × 0) 1275 ft/s...7.0 lb 3.28 Remington 5 Table 3. Recoil-related characteristics of selected shoulder-fired weapons cited in table 1. Nomenclature

  1. Optimal Control of Active Recoil Mechanisms

    DTIC Science & Technology

    1977-02-01

    forces from 25 to 2.5% for lower zones and cavitation was avoided for zone 8. Tachometer feedback was shown to be effective for low zones. The...concept of feedback control system coupled with optimization procedure to design recoil mechanisms was demonstrated to be an efficient and very effective ...122o •nl260 .01300 .01340 .01380 • ouzo #01460 •01500 •01540 •01580 •0162" .0166 i 309o,6 504P.6 9964.5 10075,9 39121.5 75397.3

  2. Musett: A segmented Si array for Recoil-Decay-Tagging studies at VAMOS

    NASA Astrophysics Data System (ADS)

    Theisen, Ch.; Jeanneau, F.; Sulignano, B.; Druillole, F.; Ljungvall, J.; Paul, B.; Virique, E.; Baron, P.; Bervas, H.; Clément, E.; Delagnes, E.; Dijon, A.; Dossat, E.; Drouart, A.; Farget, F.; Flouzat, Ch.; De France, G.; Görgen, A.; Houarner, Ch.; Jacquot, B.; Korten, W.; Lebertre, G.; Lecornu, B.; Legeard, L.; Lermitage, A.; Lhenoret, S.; Marry, C.; Maugeais, C.; Menager, L.; Meunier, O.; Navin, A.; Nizery, F.; Obertelli, A.; Rauly, E.; Raine, B.; Rejmund, M.; Ropert, J.; Saillant, F.; Savajols, H.; Schmitt, Ch.; Tripon, M.; Wanlin, E.; Wittwer, G.

    2014-05-01

    A new segmented silicon-array called MUSETT has been built for the study of heavy elements using the Recoil-Decay-Tagging technique. MUSETT is located at the focal plane of the VAMOS spectrometer at GANIL and is used in conjunction with a γ-ray array at the target position. This paper describes the device, which consists of four 10×10 cm2 Si detectors and its associated front-end electronics based on highly integrated ASICs electronics. The triggerless readout electronics, the data acquisition and the analysis tools developed for its characterization are presented. This device was commissioned at GANIL with the EXOGAM γ-ray spectrometer using the fusion-evaporation reaction 197Au(22Ne,5n)214Ac. Additionally, the performance of the VAMOS Wien filter used during the in-beam commissioning is also reported.

  3. Effects of high frequency current in welding aluminum alloy 6061

    NASA Technical Reports Server (NTRS)

    Fish, R. E.

    1968-01-01

    Uncontrolled high frequency current causes cracking in the heat-affected zone of aluminum alloy 6061 weldments during tungsten inert gas ac welding. Cracking developed when an improperly adjusted superimposed high frequency current was agitating the semimolten metal in the areas of grain boundary.

  4. Influence of Smoking on Ultra-High-Frequency Auditory Sensitivity.

    PubMed

    Prabhu, Prashanth; Varma, Gowtham; Dutta, Kristi Kaveri; Kumar, Prajwal; Goyal, Swati

    2017-04-01

    In this study, an attempt was made to determine the effect of smoking on ultra-high-frequency auditory sensitivity. The study also attempted to determine the relationship between the nature of smoking and ultra-high-frequency otoacoustic emissions (OAEs) and thresholds. The study sample included 25 smokers and 25 non-smokers. A detailed history regarding their smoking habits was collected. High-frequency audiometric thresholds and amplitudes of high-frequency distortion-product OAEs were analyzed for both ears from all participants. The results showed that the ultra-high-frequency thresholds were elevated and that there was reduction in the amplitudes of ultra-high-frequency OAEs in smokers. There was an increased risk of auditory damage with chronic smoking. The study results highlight the application of ultra-high-frequency OAEs and ultra-high-frequency audiometry for the early detection of auditory impairment. However, similar studies should be conducted on a larger population for better generalization of the results.

  5. Monitoring method and apparatus using high-frequency carrier

    DOEpatents

    Haynes, H.D.

    1996-04-30

    A method and apparatus for monitoring an electrical-motor-driven device by injecting a high frequency carrier signal onto the power line current. The method is accomplished by injecting a high frequency carrier signal onto an AC power line current. The AC power line current supplies the electrical-motor-driven device with electrical energy. As a result, electrical and mechanical characteristics of the electrical-motor-driven device modulate the high frequency carrier signal and the AC power line current. The high frequency carrier signal is then monitored, conditioned and demodulated. Finally, the modulated high frequency carrier signal is analyzed to ascertain the operating condition of the electrical-motor-driven device. 6 figs.

  6. Monitoring method and apparatus using high-frequency carrier

    DOEpatents

    Haynes, Howard D.

    1996-01-01

    A method and apparatus for monitoring an electrical-motor-driven device by injecting a high frequency carrier signal onto the power line current. The method is accomplished by injecting a high frequency carrier signal onto an AC power line current. The AC power line current supplies the electrical-motor-driven device with electrical energy. As a result, electrical and mechanical characteristics of the electrical-motor-driven device modulate the high frequency carrier signal and the AC power line current. The high frequency carrier signal is then monitored, conditioned and demodulated. Finally, the modulated high frequency carrier signal is analyzed to ascertain the operating condition of the electrical-motor-driven device.

  7. Modeling the Observability of Recoiling Black Holes as Offset Quasars

    NASA Astrophysics Data System (ADS)

    Blecha, Laura; Torrey, Paul; Vogelsberger, Mark; Genel, Shy; Springel, Volker; Sijacki, Debora; Snyder, Gregory; Bird, Simeon; Nelson, Dylan; Xu, Dandan; Hernquist, Lars

    The merger of two supermassive black holes (SMBHs) imparts a gravitational-wave (GW) recoil kick to the remnant SMBH, which can even eject the SMBH from its host galaxy. An actively-accreting, recoiling SMBH may be observable as an offset quasar. Prior to the advent of a space-based GW observatory, detections of these offset quasars may offer the best chance for identifying recent SMBH mergers. Indeed, observational searches for recoiling quasars have already identified several promising candidates. However, systematic searches for recoils are currently hampered by large uncertainties regarding how often offset quasars should be observable and where they are most likely to be found. Motivated by this, we have developed a model for recoiling quasars in a cosmological framework, utilizing information about the progenitor galaxies from the Illustris cosmological hydrodynamic simulations. For the first time, we model the effects of BH spin alignment and recoil dynamics based on the gas-richness of host galaxies. We predict that if BH spins are not highly aligned, seeing-limited observations could resolve offset AGN, making them promising targets for all-sky surveys. The rarity of large broad-line offsets among SDSS quasars is likely due in part to selection effects but suggests that spin alignment plays a role in suppressing recoils. Nonetheless, in our most physically motivated model where alignment occurs only in gas-rich mergers, hundreds of offset AGN should be found in all-sky surveys. Our findings strongly motivate a dedicated search for recoiling AGN.

  8. Heavy ion recoil spectrometry of barium strontium titanate films

    NASA Astrophysics Data System (ADS)

    Stannard, W. B.; Johnston, P. N.; Walker, S. R.; Bubb, I. F.; Scott, J. F.; Cohen, D. D.; Dytlewski, N.; Martin, J. W.

    1995-05-01

    Thin films of barium strontium titanate have been analysed using heavy ion recoil spectrometry with 77 and 98 MeV 127I ions at the new heavy ion recoil facility at ANSTO, Lucas Heights. New calibration procedures have been developed for quantitative analysis. Energy spectra for each of the elements present reveal interdiffusion that was not previously known.

  9. Spectrometer gun

    DOEpatents

    Waechter, D.A.; Wolf, M.A.; Umbarger, C.J.

    1981-11-03

    A hand-holdable, battery-operated, microprocessor-based spectrometer gun is described that includes a low-power matrix display and sufficient memory to permit both real-time observation and extended analysis of detected radiation pulses. Universality of the incorporated signal processing circuitry permits operation with various detectors having differing pulse detection and sensitivity parameters.

  10. Spectrometer gun

    DOEpatents

    Waechter, David A.; Wolf, Michael A.; Umbarger, C. John

    1985-01-01

    A hand-holdable, battery-operated, microprocessor-based spectrometer gun includes a low-power matrix display and sufficient memory to permit both real-time observation and extended analysis of detected radiation pulses. Universality of the incorporated signal processing circuitry permits operation with various detectors having differing pulse detection and sensitivity parameters.

  11. HISS spectrometer

    SciTech Connect

    Greiner, D.E.

    1984-11-01

    This talk describes the Heavy Ion Spectrometer System (HISS) facility at the Lawrence Berkeley Laboratory's Bevalac. Three completed experiments and their results are illustrated. The second half of the talk is a detailed discussion of the response of drift chambers to heavy ions. The limitations of trajectory measurement over a large range in incident particle charge are presented.

  12. Recoil Experiments Using a Compressed Air Cannon

    NASA Astrophysics Data System (ADS)

    Taylor, Brett

    2006-12-01

    Ping-Pong vacuum cannons, potato guns, and compressed air cannons are popular and dramatic demonstrations for lecture and lab.1-3 Students enjoy them for the spectacle, but they can also be used effectively to teach physics. Recently we have used a student-built compressed air cannon as a laboratory activity to investigate impulse, conservation of momentum, and kinematics. It is possible to use the cannon, along with the output from an electronic force plate, as the basis for many other experiments in the laboratory. In this paper, we will discuss the recoil experiment done by our students in the lab and also mention a few other possibilities that this apparatus could be used for.

  13. [Experiences in high frequency audiometry and possible applications (author's transl)].

    PubMed

    Dieroff, H G

    1976-09-01

    Observations on the ultrasonic perception of noise-impaired persons gave rise to use the high frequency audiometry described by Fletcher for the early recognition of noise-induced damages. Using commercial equipment we found that the earpiece was not adapted to high frequency conditions. The adaptation problem and ways of modification are described in detail. After having improved the coupling features reproducible hearing curves were obtained. Examinations were carried out on workers, whose noise exposure exceeded the critical intensity by only a few dB. The following 3 categories of impairment were found: 1. Normal hearing between 125 and 8,000 Hz as well as in the high frequency region. 2. Unsignificant noise-induced impairments between 125 and 8,000 Hz; no high frequency hearing. 3. Acoustic hearing; no high frequency hearing. The results are discussed. It is supposed that high frequency hearing losses due to noise and chemical noxious exposure (streptomycin) are valuable in diagnostics and prognostics. Accordingly persons are to be assessed as noise sensitive, when there is no more high frequency hearing before practising noise work.

  14. High-frequency energy in singing and speech

    NASA Astrophysics Data System (ADS)

    Monson, Brian Bruce

    While human speech and the human voice generate acoustical energy up to (and beyond) 20 kHz, the energy above approximately 5 kHz has been largely neglected. Evidence is accruing that this high-frequency energy contains perceptual information relevant to speech and voice, including percepts of quality, localization, and intelligibility. The present research was an initial step in the long-range goal of characterizing high-frequency energy in singing voice and speech, with particular regard for its perceptual role and its potential for modification during voice and speech production. In this study, a database of high-fidelity recordings of talkers was created and used for a broad acoustical analysis and general characterization of high-frequency energy, as well as specific characterization of phoneme category, voice and speech intensity level, and mode of production (speech versus singing) by high-frequency energy content. Directionality of radiation of high-frequency energy from the mouth was also examined. The recordings were used for perceptual experiments wherein listeners were asked to discriminate between speech and voice samples that differed only in high-frequency energy content. Listeners were also subjected to gender discrimination tasks, mode-of-production discrimination tasks, and transcription tasks with samples of speech and singing that contained only high-frequency content. The combination of these experiments has revealed that (1) human listeners are able to detect very subtle level changes in high-frequency energy, and (2) human listeners are able to extract significant perceptual information from high-frequency energy.

  15. Structural drilling using the high-frequency (sonic) rotary method

    NASA Astrophysics Data System (ADS)

    Šporin, Jurij; Vukelić, Željko

    2017-03-01

    In Slovenia, there is widespread use of structural drilling along with classical core drilling. Recently, however, the need has arisen for a highly effective core drilling method with the aid of which high-quality core might be obtained. In order to achieve this aim, one among several Slovenian companies dealing with geological surveying has decided to implement structural drilling using a high-frequency drilling method. The following article presents the theoretical foundations for such a high-frequency method, as well as the manner of its implementation. In the final part of the article, a practical comparison between the conventional and the high-frequency core drilling methods is also provided.

  16. High-frequency threshold measurements using insert earphones.

    PubMed

    Tang, H; Letowski, T

    1992-10-01

    Several recent studies have reported large intersubject variability of high-frequency thresholds measured with circumaural earphones. In the present study, high-frequency thresholds of 10 subjects were measured with circumaural (Sennheiser HD-250) and insert (Etymotic ER-1) earphones at 10, 12, 14, and 16 kHz. Overall results show significantly smaller variability of the threshold data obtained with insert earphones than with circumaural earphones. The above data indicate that insert earphones may be more suitable for high-frequency testing than circumaural earphones.

  17. Spectrometers for fast neutrons from solar flares.

    PubMed

    Slobodrian, R J; Potvin, L; Rioux, C

    1994-10-01

    Neutrons with energies exceeding 1 GeV are emitted in the course of solar flares. Suitable dedicated neutron spectrometers with directional characteristics are necessary for a systematic spectroscopy of solar neutrons. We report here a study of instruments based on the detection of proton recoils from hydrogenous media, with double scattering in order to provide directional information, and also a novel scheme based on the detection of radiation from the neutron magnetic dipole moment, permitting also directional detection of neutrons. Specific designs and detection systems are discussed.

  18. High-frequency matrix converter with square wave input

    DOEpatents

    Carr, Joseph Alexander; Balda, Juan Carlos

    2015-03-31

    A device for producing an alternating current output voltage from a high-frequency, square-wave input voltage comprising, high-frequency, square-wave input a matrix converter and a control system. The matrix converter comprises a plurality of electrical switches. The high-frequency input and the matrix converter are electrically connected to each other. The control system is connected to each switch of the matrix converter. The control system is electrically connected to the input of the matrix converter. The control system is configured to operate each electrical switch of the matrix converter converting a high-frequency, square-wave input voltage across the first input port of the matrix converter and the second input port of the matrix converter to an alternating current output voltage at the output of the matrix converter.

  19. An inkjet vision measurement technique for high-frequency jetting

    SciTech Connect

    Kwon, Kye-Si Jang, Min-Hyuck; Park, Ha Yeong; Ko, Hyun-Seok

    2014-06-15

    Inkjet technology has been used as manufacturing a tool for printed electronics. To increase the productivity, the jetting frequency needs to be increased. When using high-frequency jetting, the printed pattern quality could be non-uniform since the jetting performance characteristics including the jetting speed and droplet volume could vary significantly with increases in jet frequency. Therefore, high-frequency jetting behavior must be evaluated properly for improvement. However, it is difficult to measure high-frequency jetting behavior using previous vision analysis methods, because subsequent droplets are close or even merged. In this paper, we present vision measurement techniques to evaluate the drop formation of high-frequency jetting. The proposed method is based on tracking target droplets such that subsequent droplets can be excluded in the image analysis by focusing on the target droplet. Finally, a frequency sweeping method for jetting speed and droplet volume is presented to understand the overall jetting frequency effects on jetting performance.

  20. Self-demodulation of high-frequency ultrasound.

    PubMed

    Vos, Hendrik J; Goertz, David E; de Jong, Nico

    2010-03-01

    High-frequency (>10 MHz) ultrasound is used in, e.g., small animal imaging or intravascular applications. Currently available ultrasound contrast agents (UCAs) have a suboptimal response for high frequencies. This study therefore investigates the nonlinear propagation effects in a high-frequency ultrasound field (25 MHz) and its use for standard UCA and diagnostic frequencies (1-3 MHz). Nonlinear mixing of two high-frequency carrier waves produces a low-frequency wave, known as the self-demodulation or parametric array effect. Hydrophone experiments showed that the self-demodulated field of a focused 25 MHz transducer (850 kPa source pressure) has an amplitude of 45 kPa at 1.5 MHz in water. Such pressure level is sufficient for UCA excitation. Experimental values are confirmed by numerical simulations using the Khokhlov-Zabolotskaya-Kuznetsov equation on a spatially convergent grid.

  1. An inkjet vision measurement technique for high-frequency jetting.

    PubMed

    Kwon, Kye-Si; Jang, Min-Hyuck; Park, Ha Yeong; Ko, Hyun-Seok

    2014-06-01

    Inkjet technology has been used as manufacturing a tool for printed electronics. To increase the productivity, the jetting frequency needs to be increased. When using high-frequency jetting, the printed pattern quality could be non-uniform since the jetting performance characteristics including the jetting speed and droplet volume could vary significantly with increases in jet frequency. Therefore, high-frequency jetting behavior must be evaluated properly for improvement. However, it is difficult to measure high-frequency jetting behavior using previous vision analysis methods, because subsequent droplets are close or even merged. In this paper, we present vision measurement techniques to evaluate the drop formation of high-frequency jetting. The proposed method is based on tracking target droplets such that subsequent droplets can be excluded in the image analysis by focusing on the target droplet. Finally, a frequency sweeping method for jetting speed and droplet volume is presented to understand the overall jetting frequency effects on jetting performance.

  2. A gun recoil system employing a magnetorheological fluid damper

    NASA Astrophysics Data System (ADS)

    Li, Z. C.; Wang, J.

    2012-10-01

    This research aims to design and control a full scale gun recoil buffering system which works under real firing impact loading conditions. A conventional gun recoil absorber is replaced with a controllable magnetorheological (MR) fluid damper. Through dynamic analysis of the gun recoil system, a theoretical model for optimal design and control of the MR fluid damper for impact loadings is derived. The optimal displacement, velocity and optimal design rules are obtained. By applying the optimal design theory to protect against impact loadings, an MR fluid damper for a full scale gun recoil system is designed and manufactured. An experimental study is carried out on a firing test rig which consists of a 30 mm caliber, multi-action automatic gun with an MR damper mounted to the fixed base through a sliding guide. Experimental buffering results under passive control and optimal control are obtained. By comparison, optimal control is better than passive control, because it produces smaller variation in the recoil force while achieving less displacement of the recoil body. The optimal control strategy presented in this paper is open-loop with no feedback system needed. This means that the control process is sensor-free. This is a great benefit for a buffering system under impact loading, especially for a gun recoil system which usually works in a harsh environment.

  3. High frequency ultrasound with color Doppler in dermatology*

    PubMed Central

    Barcaui, Elisa de Oliveira; Carvalho, Antonio Carlos Pires; Lopes, Flavia Paiva Proença Lobo; Piñeiro-Maceira, Juan; Barcaui, Carlos Baptista

    2016-01-01

    Ultrasonography is a method of imaging that classically is used in dermatology to study changes in the hypoderma, as nodules and infectious and inflammatory processes. The introduction of high frequency and resolution equipments enabled the observation of superficial structures, allowing differentiation between skin layers and providing details for the analysis of the skin and its appendages. This paper aims to review the basic principles of high frequency ultrasound and its applications in different areas of dermatology. PMID:27438191

  4. Basis of Ionospheric Modification by High-Frequency Waves

    DTIC Science & Technology

    2007-06-01

    for conducting ionospheric heating experiments in Gakona, Alaska, as part of the High Frequency Active Auroral Research Program ( HAARP ) [5], is being...upgraded. The upgraded HAARP HF transmitting system will be a phased-array antenna of 180 elements. Each element is a cross dipole, which radiates a...supported by the High Frequency Active Auroral Research Program ( HAARP ), the Air Force Research Laboratory at Hanscom Air Force Base, MA, and by the Office

  5. High frequency, small signal MH loops of ferromagnetic thin films

    NASA Technical Reports Server (NTRS)

    Grimes, C. A.; Ong, K. G.

    2000-01-01

    A method is presented for transforming the high frequency bias susceptibility measurements of ferromagnetic thin films into the form of a MH loop with, depending upon the measurement geometry, the y-axis zero crossing giving a measure of the coercive force or anisotropy field. The loops provide a measure of the quantitative and qualitative high frequency switching properties of ferromagnetic thin films. c2000 American Institute of Physics.

  6. The Spectrometer

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2012-01-01

    In the fall of 1999 I was shown an Ocean Optics spectrometer-in-the-computer at St. Patricks College at Maynooth, Ireland, and thought that I had seen heaven. Of course, it could not resolve the sodium D-lines (I had done that many years before with a homemade wire diffraction grating), and I began to realize that inside was some familiar old…

  7. The Spectrometer

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2012-03-01

    In the fall of 1999 I was shown an Ocean Optics spectrometer-in-the-computer at St. Patricks College at Maynooth, Ireland, and thought that I had seen heaven. Of course, it could not resolve the sodium D-lines (I had done that many years before with a homemade wire diffraction grating ), and I began to realize that inside was some familiar old technology. In this paper I would like to discuss its ancestors.

  8. The Spectrometer

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2012-01-01

    In the fall of 1999 I was shown an Ocean Optics spectrometer-in-the-computer at St. Patricks College at Maynooth, Ireland, and thought that I had seen heaven. Of course, it could not resolve the sodium D-lines (I had done that many years before with a homemade wire diffraction grating), and I began to realize that inside was some familiar old…

  9. Characterizing Earthquake Rupture Properties Using Peak High-Frequency Offset

    NASA Astrophysics Data System (ADS)

    Wen, L.; Meng, L.

    2014-12-01

    Teleseismic array back-projection (BP) of high frequency (~1Hz) seismic waves has been recently applied to image the aftershock sequence of the Tohoku-Oki earthquake. The BP method proves to be effective in capturing early aftershocks that are difficult to be detected due to the contamination of the mainshock coda wave. Furthermore, since the event detection is based on the identification of the local peaks in time series of the BP power, the resulting event location corresponds to the peak high-frequency energy rather than the hypocenter. In this work, we show that the comparison between the BP-determined catalog and conventional phase-picking catalog provides estimates of the spatial and temporal offset between the hypocenter and the peak high-frequency radiation. We propose to measure this peak high-frequency shift of global earthquakes between M4.0 to M7.0. We average the BP locations calibrated by multiple reference events to minimize the uncertainty due to the variation of 3D path effects. In our initial effort focusing on the foreshock and aftershock sequence of the 2014 Iquique earthquake, we find systematic shifts of the peak high-frequency energy towards the down-dip direction. We find that the amount of the shift is a good indication of rupture length, which scales with the earthquake magnitude. Further investigations of the peak high frequency offset may provide constraints on earthquake source properties such as rupture directivity, rupture duration, rupture speed, and stress drop.

  10. Difference between a Photon's Momentum and an Atom's Recoil

    SciTech Connect

    Gibble, Kurt

    2006-08-18

    When an atom absorbs a photon from a laser beam that is not an infinite plane wave, the atom's recoil is less than ({Dirac_h}/2{pi})k in the propagation direction. We show that the recoils in the transverse directions produce a lensing of the atomic wave functions, which leads to a frequency shift that is not discrete but varies linearly with the field amplitude and strongly depends on the atomic state detection. The same lensing effect is also important for microwave atomic clocks. The frequency shifts are of the order of the naive recoil shift for the transverse wave vector of the photons.

  11. Extended high frequency audiometry in users of personal listening devices.

    PubMed

    Kumar, Poornima; Upadhyay, Prabhakar; Kumar, Ashok; Kumar, Sunil; Singh, Gautam Bir

    Noise exposure leads to high frequency hearing loss. Use of Personal Listening Devices may lead to decline in high frequency hearing sensitivity because of prolonged exposure to these devices at high volume. This study explores the changes in hearing thresholds by Extended High Frequency audiometry in users of personal listening devices. A descriptive, hospital based observational study was performed with total 100 subjects in age group of 15-30years. Subjects were divided in two groups consisting of 30 subjects (Group A) with no history of Personal Listening Devices use and (Group B) having 70 subjects with history of use of Personal Listening Devices. Conventional pure tone audiometry with extended high frequency audiometry was performed in all the subjects. Significant differences in hearing thresholds of Personal Listening Device users were seen at high frequencies (3kHz, 4kHz and 6kHz) and extended high frequencies (9kHz, 10kHz, 11kHz, 13kHz, 14kHz, 15kHz and 16kHz) with p value <0.05. Elevated hearing thresholds were observed in personal listening devices users which were directly proportional to volume and duration of usage. In present study no significant changes were noted in hearing thresholds in PLD users before 5years of PLD use. However, hearing thresholds were significantly increased at 3kHz, 10kHz, 13kHz in PLD users having >5years usage at high volume. Thus, it can be reasonably concluded that extended high frequencies can be used for early detection of NIHL in PLD users. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Exerpts from the history of alpha recoils.

    PubMed

    Samuelsson, Christer

    2011-05-01

    Any confined air volume holding radon ((222)Rn) gas bears a memory of past radon concentrations due to (210)Pb (T(1/2) = 22 y) and its progenies entrapped in all solid objects in the volume. The efforts of quantifying past radon exposures by means of the left-behind long-lived radon progenies started in 1987 with this author's unsuccessful trials of removing (214)Po from radon exposed glass objects. In this contribution the history and different techniques of assessing radon exposure to man in retrospect will be overviewed. The main focus will be on the implantation of alpha recoils into glass surfaces, but also potential traps in radon dwellings will be discussed. It is concluded that for a successful retrospective application, three crucial imperatives must be met, i.e. firstly, the object must persistently store a certain fraction of the created (210)Pb atoms, secondly, be resistant over decades towards disturbances from the outside and thirdly, all (210)Pb atoms analysed must originate from airborne radon only. For large-scale radon epidemiological studies, non-destructive and inexpensive measurement techniques are essential. Large-scale studies cannot be based on objects rarely found in dwellings or not available for measurements. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. A Proton Recoil Telescope for Neutron Spectroscopy

    NASA Astrophysics Data System (ADS)

    Cinausero, M.; Barbui, M.; Prete, G.; Rizzi, V.; Andrighetto, A.; Pesente, S.; Fabris, D.; Lunardon, M.; Nebbia, G.; Viesti, G.; Moretto, S.; Morando, M.; Zenoni, A.; Bocci, F.; Donzella, A.; Bonomi, G.; Fontana, A.

    2006-05-01

    The N2P research program funded by the INFN committee for Experimental Nuclear Physics (CSNIII) has among his goals the construction of a Proton Recoil Telescope (PRT), a detector to measure neutron energy spectra. The interest in such a detector is primarily related to the SPES project for rare beams production at the Laboratori Nazionali di Legnaro. For the SPES project it is, in fact, of fundamental importance to have reliable information about energy spectra and yield for neutrons produced by d or p projectiles on thick light targets to model the ''conversion target'' in which the p or d are converted in neutrons. These neutrons, in a second stage, will induce the Uranium fission in the ''production target''. The fission products are subsequently extracted, selected and re-accelerated to produce the exotic beam. The neutron spectra and angular distribution are important parameters to define the final production of fission fragments. In addition, this detector can be used to measure neutron spectra in the field of cancer therapy (this topic is nowadays of particular interest to INFN, for the National Centre for Hadron therapy (CNAO) in Pavia) and space applications.

  14. Binary Black Hole Mergers and Recoil Kicks

    NASA Technical Reports Server (NTRS)

    Centrella, Joan; Baker, J.; Choi, D.; Koppitz, M.; vanMeter, J.; Miller, C.

    2006-01-01

    Recent developments in numerical relativity have made it possible to follow reliably the coalescence of two black holes from near the innermost stable circular orbit to final ringdown. This opens up a wide variety of exciting astrophysical applications of these simulations. Chief among these is the net kick received when two unequal mass or spinning black holes merge. The magnitude of this kick has bearing on the production and growth of supermassive black holes during the epoch of structure formation, and on the retention of black holes in stellar clusters. Here we report the first accurate numerical calculation of this kick, for two nonspinning black holes in a 1.5:1 mass ratio, which is expected based on analytic considerations to give a significant fraction of the maximum possible recoil. We have performed multiple runs with different initial separations, orbital angular momenta, resolutions, extraction radii, and gauges. The full range of our kick speeds is 86-116 kilometers per second, and the most reliable runs give kicks between 86 and 97 kilometers per second. This is intermediate between the estimates from two recent post-Newtonian analyses and suggests that at redshifts z greater than 10, halos with masses less than 10(exp 9) M(sub SUN) will have difficulty retaining coalesced black holes after major mergers.

  15. MASS SPECTROMETER

    DOEpatents

    White, F.A.

    1960-08-23

    A mass spectrometer is designed with a first adjustable magnetic field for resolving an ion beam into beams of selected masses, a second adjustable magnetic field for further resolving the ion beam from the first field into beams of selected masses, a thin foil disposed in the path of the beam between the first and second magnets to dissociate molecular ions incident thereon, an electrostatic field for further resolving the ion beam from the second field into beams of selected masses, and a detector disposed adjacent to the electrostatic field to receive the ion beam.

  16. An Experimental Study of Electromagnetic Lorentz Force and Rail Recoil

    DTIC Science & Technology

    2009-12-01

    MOTIVATION For over 200 years, electromagnetic forces have been extensively researched. During 1802 , Gian Domenico Romagnosi noticed that a magnetic...C. Woods, “Comment: Origin, location, magnitude and consequences of recoil in the plasma armature railgun,” Inst. Elect. Eng. Proc. Sci. Meas...22, pp. 849-850, 1989. [26] A. E. Witalis, “Origin, location, magnitude and consequences of recoil in the plasma armature railgun,” Inst. Elect

  17. RECOILING SUPERMASSIVE BLACK HOLES IN SPIN-FLIP RADIO GALAXIES

    SciTech Connect

    Liu, F. K.; Wang Dong; Chen Xian

    2012-02-20

    Numerical relativity simulations predict that coalescence of supermassive black hole (SMBH) binaries leads not only to a spin flip but also to a recoiling of the merger remnant SMBHs. In the literature, X-shaped radio sources are popularly suggested to be candidates for SMBH mergers with spin flip of jet-ejecting SMBHs. Here we investigate the spectral and spatial observational signatures of the recoiling SMBHs in radio sources undergoing black hole spin flip. Our results show that SMBHs in most spin-flip radio sources have mass ratio q {approx}> 0.3 with a minimum possible value q{sub min} {approx_equal} 0.05. For major mergers, the remnant SMBHs can get a kick velocity as high as 2100 km s{sup -1} in the direction within an angle {approx}< 40 Degree-Sign relative to the spin axes of remnant SMBHs, implying that recoiling quasars are biased to be with high Doppler-shifted broad emission lines while recoiling radio galaxies are biased to large apparent spatial off-center displacements. We also calculate the distribution functions of line-of-sight velocity and apparent spatial off-center displacements for spin-flip radio sources with different apparent jet reorientation angles. Our results show that the larger the apparent jet reorientation angle is, the larger the Doppler-shifting recoiling velocity and apparent spatial off-center displacement will be. We investigate the effects of recoiling velocity on the dust torus in spin-flip radio sources and suggest that recoiling of SMBHs would lead to 'dust-poor' active galactic nuclei. Finally, we collect a sample of 19 X-shaped radio objects and for each object give the probability of detecting the predicted signatures of recoiling SMBH.

  18. High frequency ocean acoustic tomography observation at coastal estuary areas

    NASA Astrophysics Data System (ADS)

    Zhao, Zongxi; Zhang, Yu; Yang, Wuyi; Chen, Dongsheng

    2012-11-01

    The ocean acoustic tomography (OAT) technique can obtain oceanographic information and has received much interest. High frequency OAT (in a narrow kHz range) can be used for small and confined areas, such as estuaries and bays, with complicated hydrological conditions. In this study, we investigate the application of high-frequency reciprocal transmission OAT to assess the sound speed, temperature, and current field in the Xiamen sea area using computer simulations and sea experiments. Based on the temperature data obtained from remote sensing and the predefined stream function, high frequency OAT is employed to reconstruct the two-dimensional sound speed, temperature, and current fields of a 1.2km×1.2km small-scale region. The correlation coefficient of the computer inversion result and the original data is higher than 0.8. The result shows that increasing the number of acoustic stations decreases the influence of the travel-time errors in high frequency OAT; however, excessively increasing the number of stations could not significantly improve the inversion accuracy. Furthermore, this method has been tested by a sea experiment on monitoring the shallow water temperature of Wuyuan Bay. High frequency OAT might provide an effective method for temperature and current observation at coastal estuary areas.

  19. High-frequency thresholds: circumaural earphone versus insert earphone.

    PubMed

    Valente, M; Valente, M; Goebel, J

    1992-11-01

    Benefits of high-frequency audiometry in monitoring hearing sensitivity of patients administered ototoxic medications are well established. High-frequency thresholds have been reported to be variable, due in part to small differences in the placement of the earphone diaphragm over the opening of the ear canal. Reliability may be improved by using insert earphones (ER-2) when obtaining high-frequency thresholds. The purposes of this study were to determine high-frequency threshold test-retest reliability using Koss HV/1A+ and ER-2 earphones and to determine if significant differences are present between high-frequency thresholds obtained using these two earphones. Results obtained on 40 ears of 20 normal hearing adults revealed that differences between the test and retest thresholds for each earphone were not significant. Intrasubject threshold differences between the test and retest thresholds for each earphone were, for the most part, within +/- 10 dB at all test frequencies. Further, significantly greater intensity was required to measure threshold when using the ER-2 earphone when compared to the Koss HV/1A+ at all test frequencies.

  20. Portable fast-neutron spectrometer project

    SciTech Connect

    Thorngate, J.H.

    1989-12-01

    The Special Projects Division of the Hazards Control Department of Lawrence Livermore National Laboratory has a continuing project to develop neutron spectrometers for radiation-protection measurements. For the last three years we have received limited support from the DOE Personnel Neutron Dosimeter Evaluation and Upgrade Program through Battelle Pacific Northwest Laboratories to build a portable fast-neutron spectrometer. This unit will cover the energy range from 0.5 to 16 MeV by using an organic liquid scintillator to detect the recoil proton produced by the neutrons. Our goal is to make the system compact, computer operated, and battery powered. During the previous two years we developed a pulse-shape discriminator suitable for portable powered. This year we designed a stable light pulser to control the gain of the system, a housing for the detector, and the circuit needed to bias the dynodes of the photomultiplier that detects the light produced by the scintillator. 14 refs., 4 figs.

  1. Electron-recoil ion and recoil ion-projectile coincidence techniques applied to obtain absolute partial collision cross sections.

    PubMed

    Wolff, W; de Souza, Ihani J; Tavares, André C; de Oliveira, G F S; Luna, H

    2012-12-01

    We present in detail an alternative experimental set-up and data analysis, based on the electron-recoil ion and recoil ion-projectile coincidence techniques, that enable the measurement of partial pure ionization and partial charge exchange cross sections for an effusive gas jet set-up, where the absolute target density and recoil ion efficiency cannot be measured directly. The method is applied to the ionization of helium atoms due to collision with partially stripped C(3 +) projectiles. In order to check the method, the results are compared to data available in the literature where the target density and recoil ion detection efficiency were measured directly. The pure ionization channel is compared to the electron capture channel.

  2. Switch over to the high frequency rf systems near transition

    SciTech Connect

    Brennan, J.M.; Wei, J.

    1988-01-01

    The purpose of this note is to point out that since bunch narrowing naturally occurs in the acceleration process in the vicinity of transition, it should be possible to switch over to the high frequency system close to transition when the bunch has narrowed enough to fit directly into the high frequency bucket. The advantage of this approach is the simplicity, no extra components or gymnastics are required of the low frequency system. The disadvantage, of course, is for protons which do not go through transition. But on the other hand, there is no shortage of intensity for protons and so it should be possible to keep the phase space area low for protons, and then matching to the high frequency bucket should be easily accomplished by adiabatic compression. 3 refs., 7 figs.

  3. Design of matching layers for high-frequency ultrasonic transducers

    NASA Astrophysics Data System (ADS)

    Fei, Chunlong; Ma, Jianguo; Chiu, Chi Tat; Williams, Jay A.; Fong, Wayne; Chen, Zeyu; Zhu, BenPeng; Xiong, Rui; Shi, Jing; Hsiai, Tzung K.; Shung, K. Kirk; Zhou, Qifa

    2015-09-01

    Matching the acoustic impedance of high-frequency (≥100 MHz) ultrasound transducers to an aqueous loading medium remains a challenge for fabricating high-frequency transducers. The traditional matching layer design has been problematic to establish high matching performance given requirements on both specific acoustic impedance and precise thickness. Based on both mass-spring scheme and microwave matching network analysis, we interfaced metal-polymer layers for the matching effects. Both methods hold promises for guiding the metal-polymer matching layer design. A 100 MHz LiNbO3 transducer was fabricated to validate the performance of the both matching layer designs. In the pulse-echo experiment, the transducer echo amplitude increased by 84.4% and its -6dB bandwidth increased from 30.2% to 58.3% comparing to the non-matched condition, demonstrating that the matching layer design method is effective for developing high-frequency ultrasonic transducers.

  4. Design of matching layers for high-frequency ultrasonic transducers.

    PubMed

    Fei, Chunlong; Ma, Jianguo; Chiu, Chi Tat; Williams, Jay A; Fong, Wayne; Chen, Zeyu; Zhu, BenPeng; Xiong, Rui; Shi, Jing; Hsiai, Tzung K; Shung, K Kirk; Zhou, Qifa

    2015-09-21

    Matching the acoustic impedance of high-frequency (≥100 MHz) ultrasound transducers to an aqueous loading medium remains a challenge for fabricating high-frequency transducers. The traditional matching layer design has been problematic to establish high matching performance given requirements on both specific acoustic impedance and precise thickness. Based on both mass-spring scheme and microwave matching network analysis, we interfaced metal-polymer layers for the matching effects. Both methods hold promises for guiding the metal-polymer matching layer design. A 100 MHz LiNbO3 transducer was fabricated to validate the performance of the both matching layer designs. In the pulse-echo experiment, the transducer echo amplitude increased by 84.4% and its -6dB bandwidth increased from 30.2% to 58.3% comparing to the non-matched condition, demonstrating that the matching layer design method is effective for developing high-frequency ultrasonic transducers.

  5. Interface Strategy To Achieve Tunable High Frequency Attenuation.

    PubMed

    Lv, Hualiang; Zhang, Haiqian; Ji, Guangbin; Xu, Zhichuan J

    2016-03-01

    Among all polarizations, the interface polarization effect is the most effective, especially at high frequency. The design of various ferrite/iron interfaces can significantly enhance the materials' dielectric loss ability at high frequency. This paper presents a simple method to generate ferrite/iron interfaces to enhance the microwave attenuation at high frequency. The ferrites were coated onto carbonyl iron and could be varied to ZnFe2O4, CoFe2O4, Fe3O4, and NiFe2O4. Due to the ferrite/iron interface inducing a stronger dielectric loss effect, all of these materials achieved broad effective frequency width at a coating layer as thin as 1.5 mm. In particular, an effective frequency width of 6.2 GHz could be gained from the Fe@NiFe2O4 composite.

  6. Real-Time, High-Frequency QRS Electrocardiograph

    NASA Technical Reports Server (NTRS)

    Schlegel, Todd T.; DePalma, Jude L.; Moradi, Saeed

    2003-01-01

    An electronic system that performs real-time analysis of the low-amplitude, high-frequency, ordinarily invisible components of the QRS portion of an electrocardiographic signal in real time has been developed. Whereas the signals readily visible on a conventional electrocardiogram (ECG) have amplitudes of the order of a millivolt and are characterized by frequencies <100 Hz, the ordinarily invisible components have amplitudes in the microvolt range and are characterized by frequencies from about 150 to about 250 Hz. Deviations of these high-frequency components from a normal pattern can be indicative of myocardial ischemia or myocardial infarction

  7. A MEMS-based high frequency x-ray chopper.

    PubMed

    Siria, A; Dhez, O; Schwartz, W; Torricelli, G; Comin, F; Chevrier, J

    2009-04-29

    Time-resolved x-ray experiments require intensity modulation at high frequencies (advanced rotating choppers have nowadays reached the kHz range). We here demonstrate that a silicon microlever oscillating at 13 kHz with nanometric amplitude can be used as a high frequency x-ray chopper. We claim that using micro-and nanoelectromechanical systems (MEMS and NEMS), it will be possible to achieve higher frequencies in excess of hundreds of megahertz. Working at such a frequency can open a wealth of possibilities in chemistry, biology and physics time-resolved experiments.

  8. High-frequency generation in two coupled semiconductor superlattices

    NASA Astrophysics Data System (ADS)

    Matharu, Satpal; Kusmartsev, Feodor V.; Balanov, Alexander G.

    2013-10-01

    We theoretically show that two semiconductor superlattices arranged on the same substrate and coupled with the same resistive load can be used for a generation of high-frequency periodic and quasiperiodic signals. Each superlattice involved is capable to generate current oscillations associated with drift of domains of high charge concentration. However, the coupling with the common load can eventually lead to synchronization of the current oscillations in the interacting superlattices. We reveal how synchronization depends on detuning between devices and the resistance of the common load, and discuss the effects of coupling and detuning on the high-frequency power output from the system.

  9. Condenser Microphone Protective Grid Correction for High Frequency Measurements

    NASA Technical Reports Server (NTRS)

    Lee, Erik; Bennett, Reginald

    2010-01-01

    Use of a protective grid on small diameter microphones can prolong the lifetime of the unit, but the high frequency effects can complicate data interpretation. Analytical methods have been developed to correct for the grid effect at high frequencies. Specifically, the analysis pertains to quantifying the microphone protective grid response characteristics in the acoustic near field of a rocket plume noise source. A frequency response function computation using two microphones will be explained. Experimental and instrumentation setup details will be provided. The resulting frequency response function for a B&K 4944 condenser microphone protective grid will be presented, along with associated uncertainties

  10. High frequency microbubble-switched oscillations modulated by microfluidic transistors

    NASA Astrophysics Data System (ADS)

    Yang, Fanghao; Dai, Xianming; Li, Chen

    2012-08-01

    Creating high frequency two-phase oscillations (HF-TPOs) remains an important goal in advancing microscale fluidic logic devices, micro-mixers, micro-actuators, and flow controls. However, thermally driven TPO frequency has been hindered by confinements of compressible vapor bubbles and low thermal diffusivity in microfluidic systems. In this study, a mechanism creating high frequency microbubbles growth/collapse cycle has been developed to achieve HF-TPOs. A "microfluidic transistor" was conceptualized and fabricated to passively sustain and modulate HF-TPOs. Three orders of magnitude higher TPO frequency has been achieved compared to TPOs reported in literatures under similar working conditions.

  11. Casimir force between δ -δ' mirrors transparent at high frequencies

    NASA Astrophysics Data System (ADS)

    Braga, Alessandra N.; Silva, Jeferson Danilo L.; Alves, Danilo T.

    2016-12-01

    We investigate, in the context of a real massless scalar field in 1 +1 dimensions, models of partially reflecting mirrors simulated by Dirac δ -δ' point interactions. In the literature, these models do not exhibit full transparency at high frequencies. In order to provide a more realistic feature for these models, we propose a modified δ -δ' point interaction that enables full transparency in the limit of high frequencies. Taking this modified δ -δ' model into account, we investigate the Casimir force, comparing our results with those found in the literature.

  12. Lifetime measurement of 2+- state in 74Zn by recoil-distance Doppler-shift method

    NASA Astrophysics Data System (ADS)

    Niikura, M.; Mouginot, B.; Azaiez, F.; Franchoo, S.; Matea, I.; Stefan, I.; Verney, D.; Assie, M.; Bednarczyk, P.; Borcea, C.; Burger, A.; Burgunder, G.; Buta, A.; Cáceres, L.; Cléement, E.; Coquard, L.; de Angelis, G.; de France, G.; de Oliveira Santos, F.; Dewald, A.; Dijon, A.; Dombradi, Z.; Fiori, E.; Fransen, C.; Friessner, G.; Gaudefroy, L.; Georgiev, G.; Grévy, S.; Hackstein, M.; Harakeh, M. N.; Ibrahim, F.; Kamalou, O.; Kmiecik, M.; Lozeva, R.; Maj, A.; Mihai, C.; Möller, O.; Myalski, S.; Negoita, F.; Pantelica, D.; Perrot, L.; Pissulla, Th.; Rotaru, F.; Rother, W.; Scarpaci, J. A.; Stodel, C.; Thomas, J. C.; Ujic, P.

    2013-09-01

    We have performed the first direct lifetime measurement of the 2+- state in 74Zn. The neutron-rich 74Zn beam was produced by in-flight fragmentation of 76Ge at the Grand Accélérateur National d'Ions Lourds and separated with the LISE spectrometer. The lifetime of the 2+- state was measured by the recoil-distance Doppler-shift method with the Cologne plunger device combined with the EXOGAM detectors. The lifetime of the 2+- state in 74Zn was determined to be 27.0(24) ps, which corresponds to a reduced transition probability B(E2; 2+- -> 0+) = 370(33) e2fm4.

  13. Development of a new Recoil Distance Technique using Coulomb Excitation in Inverse Kinematics

    SciTech Connect

    Rother, Wolfram; Dewald, Alfred; Ilie, Gabriela; Pissulla, Thomas; Melon, Barbara; Jolie, Jan; Pascovici, Gheorghe; Iwasaki, Hironori; Hackstein, Matthias; Zell, Karl-Oskar; Julin, Rauno; Jones, Peter; Greenlees, Paul; Rahkila, Panu; Uusitalo, Juha; Scholey, Cath; Harissopulos, Sotirios; Lagoyannis, Anastasios; Konstantinopoulos, Theodore; Grahn, Tuomas

    2009-01-28

    We report on an experiment using Coulomb excitation in inverse kinematics in combination with the plunger technique for measuring lifetimes of excited states of the projectiles. Aside from the investigation of E(5) features in {sup 128}Xe, the aim was to explore the special features of such experiments which are also suited to be used with radioactive beams. The measurement was performed at the JYFL with the Koeln coincidence plunger device and the JUROGAM spectrometer using a {sup 128}Xe beam impinging on a {sup nat}Fe target at a beam energy of 525 MeV. Recoils were detected by means of 32 solar cells placed at extreme forward angles. Particle-gated {gamma}-singles and {gamma}{gamma}-coincidences were measured at different target-degrader distances. Details of the experiment and first results are presented.

  14. Recoil-α-fission and recoil-α-α-fission events observed in the reaction 48Ca + 243Am

    NASA Astrophysics Data System (ADS)

    Forsberg, U.; Rudolph, D.; Andersson, L.-L.; Di Nitto, A.; Düllmann, Ch. E.; Fahlander, C.; Gates, J. M.; Golubev, P.; Gregorich, K. E.; Gross, C. J.; Herzberg, R.-D.; Heßberger, F. P.; Khuyagbaatar, J.; Kratz, J. V.; Rykaczewski, K.; Sarmiento, L. G.; Schädel, M.; Yakushev, A.; Åberg, S.; Ackermann, D.; Block, M.; Brand, H.; Carlsson, B. G.; Cox, D.; Derkx, X.; Dobaczewski, J.; Eberhardt, K.; Even, J.; Gerl, J.; Jäger, E.; Kindler, B.; Krier, J.; Kojouharov, I.; Kurz, N.; Lommel, B.; Mistry, A.; Mokry, C.; Nazarewicz, W.; Nitsche, H.; Omtvedt, J. P.; Papadakis, P.; Ragnarsson, I.; Runke, J.; Schaffner, H.; Schausten, B.; Shi, Yue; Thörle-Pospiech, P.; Torres, T.; Traut, T.; Trautmann, N.; Türler, A.; Ward, A.; Ward, D. E.; Wiehl, N.

    2016-09-01

    Products of the fusion-evaporation reaction 48Ca + 243Am were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. Amongst the detected thirty correlated α-decay chains associated with the production of element Z = 115, two recoil-α-fission and five recoil- α- α-fission events were observed. The latter five chains are similar to four such events reported from experiments performed at the Dubna gas-filled separator, and three such events reported from an experiment at the Berkeley gas-filled separator. The four chains observed at the Dubna gas-filled separator were assigned to start from the 2n-evaporation channel 289115 due to the fact that these recoil- α- α-fission events were observed only at low excitation energies. Contrary to this interpretation, we suggest that some of these recoil- α- α-fission decay chains, as well as some of the recoil- α- α-fission and recoil-α-fission decay chains reported from Berkeley and in this article, start from the 3n-evaporation channel 288115.

  15. Computer Spectrometers

    NASA Astrophysics Data System (ADS)

    Dattani, Nikesh S.

    2017-06-01

    Ideally, the cataloguing of spectroscopic linelists would not demand laborious and expensive experiments. Whatever an experiment might achieve, the same information would be attainable by running a calculation on a computer. Kolos and Wolniewicz were the first to demonstrate that calculations on a computer can outperform even the most sophisticated molecular spectroscopic experiments of the time, when their 1964 calculations of the dissociation energies of H_2 and D_{2} were found to be more than 1 cm^{-1} larger than the best experiments by Gerhard Herzberg, suggesting the experiment violated a strict variational principle. As explained in his Nobel Lecture, it took 5 more years for Herzberg to perform an experiment which caught up to the accuracy of the 1964 calculations. Today, numerical solutions to the Schrödinger equation, supplemented with relativistic and higher-order quantum electrodynamics (QED) corrections can provide ro-vibrational spectra for molecules that we strongly believe to be correct, even in the absence of experimental data. Why do we believe these calculated spectra are correct if we do not have experiments against which to test them? All evidence seen so far suggests that corrections due to gravity or other forces are not needed for a computer simulated QED spectrum of ro-vibrational energy transitions to be correct at the precision of typical spectrometers. Therefore a computer-generated spectrum can be considered to be as good as one coming from a more conventional spectrometer, and this has been shown to be true not just for the H_2 energies back in 1964, but now also for several other molecules. So are we at the stage where we can launch an array of calculations, each with just the atomic number changed in the input file, to reproduce the NIST energy level databases? Not quite. But I will show that for the 6e^- molecule Li_2, we have reproduced the vibrational spacings to within 0.001 cm^{-1} of the experimental spectrum, and I will

  16. Absolute measurements of the high-frequency magnetic dynamics in high-{Tc} superconductors

    SciTech Connect

    Hayden, S.M.; Aeppli, G.; Dai, P.; Mook, H.A.; Perring, T.G.; Cheong, S.W.; Fisk, Z.; Dogan, F.; Mason, T.E.

    1997-08-07

    The authors review recent measurements of the high-frequency dynamic magnetic susceptibility in the high-T{sub c} superconducting systems La{sub 2{minus}x}Sr{sub x}CuO{sub 4} and YBa{sub 2}Cu{sub 3}O{sub 6+x}. Experiments were performed using the chopper spectrometers HET and MARI at the ISIS spallation source. The authors have placed their measurements on an absolute intensity scale, this allows systematic trends to be seen and comparisons with theory to be made. They find that the insulating S = 1/2 antiferromagnetic parent compounds show a dramatic renormalization in the spin wave intensity. The effect of doping on the response is to cause broadenings in wave vector and large redistributions of spectral weight in frequency.

  17. Collocations of High Frequency Noun Keywords in Prescribed Science Textbooks

    ERIC Educational Resources Information Center

    Menon, Sujatha; Mukundan, Jayakaran

    2012-01-01

    This paper analyses the discourse of science through the study of collocational patterns of high frequency noun keywords in science textbooks used by upper secondary students in Malaysia. Research has shown that one of the areas of difficulty in science discourse concerns lexis, especially that of collocations. This paper describes a corpus-based…

  18. Practical techniques for enhancing the high-frequency MASW method

    USDA-ARS?s Scientific Manuscript database

    For soil exploration in the vadose zone, a high-frequency multi-channel analysis of surface waves (HF-MASW) method has been developed. In the study, several practical techniques were applied to enhance the overtone image of the HF-MASW method. They included (1) the self-adaptive MASW method using a ...

  19. Piezoelectric films for high frequency ultrasonic transducers in biomedical applications

    PubMed Central

    Zhou, Qifa; Lau, Sienting; Wu, Dawei; Shung, K. Kirk

    2011-01-01

    Piezoelectric films have recently attracted considerable attention in the development of various sensor and actuator devices such as nonvolatile memories, tunable microwave circuits and ultrasound transducers. In this paper, an overview of the state of art in piezoelectric films for high frequency transducer applications is presented. Firstly, the basic principles of piezoelectric materials and design considerations for ultrasound transducers will be introduced. Following the review, the current status of the piezoelectric films and recent progress in the development of high frequency ultrasonic transducers will be discussed. Then details for preparation and structure of the materials derived from piezoelectric thick film technologies will be described. Both chemical and physical methods are included in the discussion, namely, the sol–gel approach, aerosol technology and hydrothermal method. The electric and piezoelectric properties of the piezoelectric films, which are very important for transducer applications, such as permittivity and electromechanical coupling factor, are also addressed. Finally, the recent developments in the high frequency transducers and arrays with piezoelectric ZnO and PZT thick film using MEMS technology are presented. In addition, current problems and further direction of the piezoelectric films for very high frequency ultrasound application (up to GHz) are also discussed. PMID:21720451

  20. Music students: conventional hearing thresholds and at high frequencies.

    PubMed

    Lüders, Débora; Gonçalves, Cláudia Giglio de Oliveira; Lacerda, Adriana Bender de Moreira; Ribas, Ângela; Conto, Juliana de

    2014-01-01

    Research has shown that hearing loss in musicians may cause difficulty in timbre recognition and tuning of instruments. To analyze the hearing thresholds from 250 Hz to 16,000 Hz in a group of music students and compare them to a non-musician group in order to determine whether high-frequency audiometry is a useful tool in the early detection of hearing impairment. Study design was a retrospective observational cohort. Conventional and high-frequency audiometry was performed in 42 music students (Madsen Itera II audiometer and TDH39P headphones for conventional audiometry, and HDA 200 headphones for high-frequency audiometry). Of the 42 students, 38.1% were female students and 61.9% were male students, with a mean age of 26 years. At conventional audiometry, 92.85% had hearing thresholds within normal limits; but even within the normal limits, the worst results were observed in the left ear for all frequencies, except for 4000 Hz; compared to the non-musician group, the worst results occurred at 500 Hz in the left ear, and at 250 Hz, 6000 Hz, 9000 Hz, 10,000 Hz, and 11,200 Hz in both the ears. The periodic evaluation of high-frequency thresholds may be useful in the early detection of hearing loss in musicians. Copyright © 2014 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  1. Measurement of high frequency waves using a wave follower

    NASA Technical Reports Server (NTRS)

    Tang, S.; Shemdin, O. H.

    1983-01-01

    High frequency waves were measured using a laser-optical sensor mounted on a wave follower. Measured down-wind wave slope spectra are shown to be wind speed dependent; the mean square wave-slopes are generally larger than those measured by Cox and Munk (1954) using the sun glitter method.

  2. Fuzzy and conventional control of high-frequency ventilation.

    PubMed

    Noshiro, M; Matsunami, T; Takakuda, K; Ryumae, S; Kagawa, T; Shimizu, M; Fujino, T

    1994-07-01

    A high-frequency ventilator was developed, consisting of a single-phase induction motor, an unbalanced mass and a mechanical vibration system. Intermittent positive pressure respiration was combined with high-frequency ventilation to measure end-tidal pCO2. Hysteresis was observed between the rotational frequency of the high-frequency ventilator and end-tidal pCO2. A fuzzy proportional plus integral control system, designed on the basis of the static characteristics of the controlled system and a knowledge of respiratory physiology, successfully regulated end-tidal pCO2. The characteristics of gas exchange under high-frequency ventilation was approximated by a first-order linear model. A conventional PI control system, designed on the basis of the approximated model, regulated end-tidal pCO2 with a performance similar to that of the fuzzy PI control system. The design of the fuzzy control system required less knowledge about the controlled system than that of the conventional control system.

  3. High-Frequency Oscillations and Seizure Generation in Neocortical Epilepsy

    ERIC Educational Resources Information Center

    Worrell, Greg A.; Parish, Landi; Cranstoun, Stephen D.; Jonas, Rachel; Baltuch, Gordon; Litt, Brian

    2004-01-01

    Neocortical seizures are often poorly localized, explosive and widespread at onset, making them poorly amenable to epilepsy surgery in the absence of associated focal brain lesions. We describe, for the first time in an unselected group of patients with neocortical epilepsy, the finding that high-frequency (60--100 Hz) epileptiform oscillations…

  4. Piezoelectric films for high frequency ultrasonic transducers in biomedical applications.

    PubMed

    Zhou, Qifa; Lau, Sienting; Wu, Dawei; Shung, K Kirk

    2011-02-01

    Piezoelectric films have recently attracted considerable attention in the development of various sensor and actuator devices such as nonvolatile memories, tunable microwave circuits and ultrasound transducers. In this paper, an overview of the state of art in piezoelectric films for high frequency transducer applications is presented. Firstly, the basic principles of piezoelectric materials and design considerations for ultrasound transducers will be introduced. Following the review, the current status of the piezoelectric films and recent progress in the development of high frequency ultrasonic transducers will be discussed. Then details for preparation and structure of the materials derived from piezoelectric thick film technologies will be described. Both chemical and physical methods are included in the discussion, namely, the sol-gel approach, aerosol technology and hydrothermal method. The electric and piezoelectric properties of the piezoelectric films, which are very important for transducer applications, such as permittivity and electromechanical coupling factor, are also addressed. Finally, the recent developments in the high frequency transducers and arrays with piezoelectric ZnO and PZT thick film using MEMS technology are presented. In addition, current problems and further direction of the piezoelectric films for very high frequency ultrasound application (up to GHz) are also discussed.

  5. High-Frequency Axial Fatigue Test Procedures for Spectrum Loading

    DTIC Science & Technology

    2016-07-20

    UNCLASSIFIED UNCLASSIFIED NAVAL AIR WARFARE CENTER AIRCRAFT DIVISION PATUXENT RIVER, MARYLAND TECHNICAL INFORMATION MEMORANDUM...REPORT NO: NAWCADPAX/TIM-2016/49 HIGH-FREQUENCY AXIAL FATIGUE TEST PROCEEDURES FOR SPECTRUM LOADING by David T. Rusk, AIR ...4.3.3.5 Robert E. Taylor, AIR 4.3.4.1 20 July 2016 Approved for public release; distribution unlimited. DEPARTMENT

  6. Factors Affecting the Benefits of High-Frequency Amplification

    ERIC Educational Resources Information Center

    Horwitz, Amy R.; Ahlstrom, Jayne B.; Dubno, Judy R.

    2008-01-01

    Purpose: This study was designed to determine the extent to which high-frequency amplification helped or hindered speech recognition as a function of hearing loss, gain-frequency response, and background noise. Method: Speech recognition was measured monaurally under headphones for nonsense syllables low-pass filtered in one-third-octave steps…

  7. Surface modification of lignocellulosic fibers using high-frequency ultrasound

    Treesearch

    Jayant B. Gadhe; Ram B. Gupta; Thomas Elder

    2005-01-01

    Enzymatic and chemical oxidation of fiber surfaces has been reported in the literature as a method for producing medium density fiberboards without using synthetic adhesives. This work focuses on modifying the surface properties of wood fibers by the generation of free radicals using high-frequency ultrasound. A sonochemical reactor operating at 610 kHz is used to...

  8. Dynamics of high-frequency synchronization during seizures.

    PubMed

    Krishnan, Giri P; Filatov, Gregory; Bazhenov, Maxim

    2013-05-01

    Pathological synchronization of neuronal firing is considered to be an inherent property of epileptic seizures. However, it remains unclear whether the synchrony increases for the high-frequency multiunit activity as well as for the local field potentials (LFPs). We present spatio-temporal analysis of synchronization during epileptiform activity using wide-band (up to 2,000 Hz) spectral analysis of multielectrode array recordings at up to 60 locations throughout the mouse hippocampus in vitro. Our study revealed a prominent structure of LFP profiles during epileptiform discharges, triggered by elevated extracellular potassium, with characteristic distribution of current sinks and sources with respect to anatomical structure. The cross-coherence of high-frequency activity (500-2,000 Hz) across channels was reduced during epileptic bursts compared with baseline activity and showed the opposite trend for lower frequencies. Furthermore, the magnitude of cross-coherence during epileptiform activity was dependent on distance: electrodes closer to the epileptic foci showed increased cross-coherence and electrodes further away showed reduced cross-coherence for high-frequency activity. These experimental observations were re-created and supported in a computational model. Our study suggests that different intrinsic and synaptic processes can mediate paroxysmal synchronization at low, medium, and high frequencies.

  9. High-frequency hearing in seals and sea lions.

    PubMed

    Cunningham, Kane A; Reichmuth, Colleen

    2016-01-01

    Existing evidence suggests that some pinnipeds (seals, sea lions, and walruses) can detect underwater sound at frequencies well above the traditional high-frequency hearing limits for their species. This phenomenon, however, is not well studied: Sensitivity patterns at frequencies beyond traditional high-frequency limits are poorly resolved, and the nature of the auditory mechanism mediating hearing at these frequencies is unknown. In the first portion of this study, auditory sensitivity patterns in the 50-180 kHz range were measured for one California sea lion (Zalophus californianus), one harbor seal (Phoca vitulina), and one spotted seal (Phoca largha). Results show the presence of two distinct slope-regions at the high-frequency ends of the audiograms of all three subjects. The first region is characterized by a rapid decrease in sensitivity with increasing frequency-i.e. a steep slope-followed by a region of much less rapid sensitivity decrease-i.e. a shallower slope. In the second portion of this study, a masking experiment was conducted to investigate how the basilar membrane of a harbor seal subject responded to acoustic energy from a narrowband masking noise centered at 140 kHz. The measured masking pattern suggests that the initial, rapid decrease in sensitivity on the high-frequency end of the subject's audiogram is not due to cochlear constraints, as has been previously hypothesized, but rather to constraints on the conductive mechanism. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. High-Frequency Oscillations and Seizure Generation in Neocortical Epilepsy

    ERIC Educational Resources Information Center

    Worrell, Greg A.; Parish, Landi; Cranstoun, Stephen D.; Jonas, Rachel; Baltuch, Gordon; Litt, Brian

    2004-01-01

    Neocortical seizures are often poorly localized, explosive and widespread at onset, making them poorly amenable to epilepsy surgery in the absence of associated focal brain lesions. We describe, for the first time in an unselected group of patients with neocortical epilepsy, the finding that high-frequency (60--100 Hz) epileptiform oscillations…

  11. Studies of high-frequency seismic wave propagation

    NASA Astrophysics Data System (ADS)

    Minster, Jean-Bernard; Berger, Jonathan

    1991-03-01

    This final report results are: (1) a study of the location of regional seismic events using a sparse network, with an application to eastern Kazakhstan; (2) an analysis of high frequency seismic observations collected in eastern Kazakhstan, including in particular calibration chemical explosions; (3) a study of the discrimination of quarry blasts from single explosions, using sonogram analysis of data collected in eastern Kazakhstan; (4) the extension of the discrimination methodology developed in the previous paper to small aperture array data, and application to the automated discrimination between earthquake and quarry blasts at NORESS; (5) the use of a new technique, labelled beam stack imaging, to map shallow crust scatterers near a small aperture array, with applications to NORESS; (6) a study of the polarization characteristics of high-frequency borehole seismograms recorded near Anza, California; and (7) an analysis of attenuation and site effects on high-frequency seismic waves, using high-frequency borehole seismograms recorded in the San Jacinto fault zone, near Anza, California.

  12. 140 GHz pulsed Fourier transform microwave spectrometer

    DOEpatents

    Kolbe, W.F.; Leskovar, B.

    1987-10-27

    A high frequency energy pulsing system suitable for use in a pulsed microwave spectrometer, including means for generating a high frequency carrier signal, and means for generating a low frequency modulating signal is disclosed. The carrier signal is continuously fed to a modulator and the modulating signal is fed through a pulse switch to the modulator. When the pulse switch is on, the modulator will produce sideband signals above and below the carrier signal frequency. A frequency-responsive device is tuned to one of the sideband signals and away from the carrier frequency so that the high frequency energization of the frequency-responsive device is controlled by the pulse switch. 5 figs.

  13. 140 GHz pulsed fourier transform microwave spectrometer

    DOEpatents

    Kolbe, William F.; Leskovar, Branko

    1987-01-01

    A high frequency energy pulsing system suitable for use in a pulsed microwave spectrometer (10), including means (11, 19) for generating a high frequency carrier signal, and means (12) for generating a low frequency modulating signal. The carrier signal is continuously fed to a modulator (20) and the modulating signal is fed through a pulse switch (23) to the modulator. When the pulse switch (23) is on, the modulator (20) will produce sideband signals above and below the carrier signal frequency. A frequency-responsive device (31) is tuned to one of the sideband signals and away from the carrier frequency so that the high frequency energization of the frequency-responsive device (31) is controlled by the pulse switch (23).

  14. Energy acceptance of the St. George recoil separator

    NASA Astrophysics Data System (ADS)

    Meisel, Z.; Moran, M. T.; Gilardy, G.; Schmitt, J.; Seymour, C.; Couder, M.

    2017-04-01

    Radiative alpha-capture, (α , γ) , reactions play a critical role in nucleosynthesis and nuclear energy generation in a variety of astrophysical environments. The St. George recoil separator at the University of Notre Dame's Nuclear Science Laboratory was developed to measure (α , γ) reactions in inverse kinematics via recoil detection in order to obtain nuclear reaction cross sections at the low energies of astrophysical interest, while avoiding the γ-background that plagues traditional measurement techniques. Due to the γ ray produced by the nuclear reaction at the target location, recoil nuclei are produced with a variety of energies and angles, all of which must be accepted by St. George in order to accurately determine the reaction cross section. We demonstrate the energy acceptance of the St. George recoil separator using primary beams of helium, hydrogen, neon, and oxygen, spanning the magnetic and electric rigidity phase space populated by recoils of anticipated (α , γ) reaction measurements. We find the performance of St. George meets the design specifications, demonstrating its suitability for (α , γ) reaction measurements of astrophysical interest.

  15. Calculation of recoil implantation profiles using known range statistics

    NASA Technical Reports Server (NTRS)

    Fung, C. D.; Avila, R. E.

    1985-01-01

    A method has been developed to calculate the depth distribution of recoil atoms that result from ion implantation onto a substrate covered with a thin surface layer. The calculation includes first order recoils considering projected range straggles, and lateral straggles of recoils but neglecting lateral straggles of projectiles. Projectile range distributions at intermediate energies in the surface layer are deduced from look-up tables of known range statistics. A great saving of computing time and human effort is thus attained in comparison with existing procedures. The method is used to calculate recoil profiles of oxygen from implantation of arsenic through SiO2 and of nitrogen from implantation of phosphorus through Si3N4 films on silicon. The calculated recoil profiles are in good agreement with results obtained by other investigators using the Boltzmann transport equation and they also compare very well with available experimental results in the literature. The deviation between calculated and experimental results is discussed in relation to lateral straggles. From this discussion, a range of surface layer thickness for which the method applies is recommended.

  16. Calculation of recoil implantation profiles using known range statistics

    NASA Technical Reports Server (NTRS)

    Fung, C. D.; Avila, R. E.

    1985-01-01

    A method has been developed to calculate the depth distribution of recoil atoms that result from ion implantation onto a substrate covered with a thin surface layer. The calculation includes first order recoils considering projected range straggles, and lateral straggles of recoils but neglecting lateral straggles of projectiles. Projectile range distributions at intermediate energies in the surface layer are deduced from look-up tables of known range statistics. A great saving of computing time and human effort is thus attained in comparison with existing procedures. The method is used to calculate recoil profiles of oxygen from implantation of arsenic through SiO2 and of nitrogen from implantation of phosphorus through Si3N4 films on silicon. The calculated recoil profiles are in good agreement with results obtained by other investigators using the Boltzmann transport equation and they also compare very well with available experimental results in the literature. The deviation between calculated and experimental results is discussed in relation to lateral straggles. From this discussion, a range of surface layer thickness for which the method applies is recommended.

  17. Submillisecond Elastic Recoil Reveals Molecular Origins of Fibrin Fiber Mechanics

    PubMed Central

    Hudson, Nathan E.; Ding, Feng; Bucay, Igal; O’Brien, E. Timothy; Gorkun, Oleg V.; Superfine, Richard; Lord, Susan T.; Dokholyan, Nikolay V.; Falvo, Michael R.

    2013-01-01

    Fibrin fibers form the structural scaffold of blood clots. Thus, their mechanical properties are of central importance to understanding hemostasis and thrombotic disease. Recent studies have revealed that fibrin fibers are elastomeric despite their high degree of molecular ordering. These results have inspired a variety of molecular models for fibrin’s elasticity, ranging from reversible protein unfolding to rubber-like elasticity. An important property that has not been explored is the timescale of elastic recoil, a parameter that is critical for fibrin’s mechanical function and places a temporal constraint on molecular models of fiber elasticity. Using high-frame-rate imaging and atomic force microscopy-based nanomanipulation, we measured the recoil dynamics of individual fibrin fibers and found that the recoil was orders of magnitude faster than anticipated from models involving protein refolding. We also performed steered discrete molecular-dynamics simulations to investigate the molecular origins of the observed recoil. Our results point to the unstructured αC regions of the otherwise structured fibrin molecule as being responsible for the elastic recoil of the fibers. PMID:23790375

  18. Automated Screening for High-Frequency Hearing Loss

    PubMed Central

    MacKinnon, Robert C.; Jansen, Marije; Moore, David R.

    2014-01-01

    Objective: Hearing loss at high frequencies produces perceptual difficulties and is often an early sign of a more general hearing loss. This study reports the development and validation of two new speech-based hearing screening tests in English that focus on detecting hearing loss at frequencies above 2000 Hz. Design: The Internet-delivered, speech-in noise tests used closed target-word sets of digit triplets or consonant–vowel–consonant (CVC) words presented against a speech-shaped noise masker. The digit triplet test uses the digits 0 to 9 (excluding the disyllabic 7), grouped in quasi-random triplets. The CVC test uses simple words (e.g., “cat”) selected for the high-frequency spectral content of the consonants. During testing, triplets or CVC words were identified in an adaptive procedure to obtain the speech reception threshold (SRT) in noise. For these new, high-frequency (HF) tests, the noise was low-pass filtered to produce greater masking of the low-frequency speech components, increasing the sensitivity of the test for HF hearing loss. Individual test tokens (digits, CVCs) were first homogenized using a group of 10 normal-hearing (NH) listeners by equalizing intelligibility across tokens at several speech-in-noise levels. Both tests were then validated and standardized using groups of 24 NH listeners and 50 listeners with hearing impairment. Performance on the new high frequency digit triplet (HF-triplet) and CVC (HF-CVC) tests was compared with audiometric hearing loss, and with that on the unfiltered, broadband digit triplet test (BB-triplet) test, and the ASL (Adaptive Sentence Lists) speech-in-noise test. Results: The HF-triplet and HF-CVC test results (SRT) both correlated positively and highly with high-frequency audiometric hearing loss and with the ASL test. SRT for both tests as a function of high-frequency hearing loss increased at nearly three times the rate as that of the BB-triplet test. The intraindividual variability (SD) on the

  19. Automated screening for high-frequency hearing loss.

    PubMed

    Vlaming, Marcel S M G; MacKinnon, Robert C; Jansen, Marije; Moore, David R

    2014-01-01

    Hearing loss at high frequencies produces perceptual difficulties and is often an early sign of a more general hearing loss. This study reports the development and validation of two new speech-based hearing screening tests in English that focus on detecting hearing loss at frequencies above 2000 Hz. The Internet-delivered, speech-in noise tests used closed target-word sets of digit triplets or consonant-vowel-consonant (CVC) words presented against a speech-shaped noise masker. The digit triplet test uses the digits 0 to 9 (excluding the disyllabic 7), grouped in quasi-random triplets. The CVC test uses simple words (e.g., "cat") selected for the high-frequency spectral content of the consonants. During testing, triplets or CVC words were identified in an adaptive procedure to obtain the speech reception threshold (SRT) in noise. For these new, high-frequency (HF) tests, the noise was low-pass filtered to produce greater masking of the low-frequency speech components, increasing the sensitivity of the test for HF hearing loss. Individual test tokens (digits, CVCs) were first homogenized using a group of 10 normal-hearing (NH) listeners by equalizing intelligibility across tokens at several speech-in-noise levels. Both tests were then validated and standardized using groups of 24 NH listeners and 50 listeners with hearing impairment. Performance on the new high frequency digit triplet (HF-triplet) and CVC (HF-CVC) tests was compared with audiometric hearing loss, and with that on the unfiltered, broadband digit triplet test (BB-triplet) test, and the ASL (Adaptive Sentence Lists) speech-in-noise test. The HF-triplet and HF-CVC test results (SRT) both correlated positively and highly with high-frequency audiometric hearing loss and with the ASL test. SRT for both tests as a function of high-frequency hearing loss increased at nearly three times the rate as that of the BB-triplet test. The intraindividual variability (SD) on the tests was about 2.1 (HF-triplet) and 1

  20. [High-frequency ventilation. I. Distribution of alveolar pressure amplitudes during high frequency oscillation in the lung model].

    PubMed

    Theissen, J; Lunkenheimer, P P; Niederer, P; Bush, E; Frieling, G; Lawin, P

    1987-09-01

    The pattern of intrapulmonary pressure distribution was studied during high-frequency ventilation in order to explain the inconsistent results reported in the literature. Methods. Pressure and flow velocity (hot-wire anemometry) were measured in different lung compartments: 1. In transalveolar chambers sealed to the perforated pleural surfaces of dried pig lungs; 2. In emphysema-simulating airbags sealed to the isolated bronchial trees of dried pig lungs; and 3. In transalveolar chambers sealed to the perforated pleural surfaces of freshly excised pig lungs. Results. 1. The pressure amplitudes change from one area to another and depending on the exciting frequency. 2. High-frequency oscillation is associated with an increase in pressure amplitude when the exciting frequency rises, whereas with conventional high-frequency jet ventilation the pressure amplitude is more likely to decrease with frequency. 3. During high-frequency jet ventilation the local pressure amplitude changes with the position of the tube in the trachea rather than with the exciting frequency. 4. When the volume of the measuring chamber is doubled the resulting pressure amplitude falls to half the control value. 5. The pressure amplitude and mean pressure measured in the transalveolar chamber vary more or less independently from the peak flow velocity. High-frequency ventilation is thus seen to be a frequency-dependant, inhomogeneous mode of ventilation that can essentially be homogenized by systematically changing the exciting frequency. The frequency-dependant response to different lung areas to excitation is likely to result from an intrabronchially-localized aerodynamic effect rather than the mechanical properties of the lung parenchyma.

  1. Recoil-Sensitive Lithium Interferometer without a Subrecoil Sample.

    PubMed

    Cassella, Kayleigh; Copenhaver, Eric; Estey, Brian; Feng, Yanying; Lai, Chen; Müller, Holger

    2017-06-09

    We report simultaneous conjugate Ramsey-Bordé interferometers with a sample of low-mass (lithium-7) atoms at 50 times the recoil temperature. We optically pump the atoms to a magnetically insensitive state using the 2S_{1/2}-2P_{1/2} line. Fast stimulated Raman beam splitters address a broad velocity class and unavoidably drive two conjugate interferometers that overlap spatially. We show that detecting the summed interference signals of both interferometers, using state labeling, allows recoil measurements and suppression of phase noise from vibrations. The use of "warm" atoms allows for simple, efficient, and high-flux atom sources and broadens the applicability of recoil-sensitive interferometry to particles that remain difficult to trap and cool.

  2. Recoil-Sensitive Lithium Interferometer without a Subrecoil Sample

    NASA Astrophysics Data System (ADS)

    Cassella, Kayleigh; Copenhaver, Eric; Estey, Brian; Feng, Yanying; Lai, Chen; Müller, Holger

    2017-06-01

    We report simultaneous conjugate Ramsey-Bordé interferometers with a sample of low-mass (lithium-7) atoms at 50 times the recoil temperature. We optically pump the atoms to a magnetically insensitive state using the 2 S1 /2-2 P1 /2 line. Fast stimulated Raman beam splitters address a broad velocity class and unavoidably drive two conjugate interferometers that overlap spatially. We show that detecting the summed interference signals of both interferometers, using state labeling, allows recoil measurements and suppression of phase noise from vibrations. The use of "warm" atoms allows for simple, efficient, and high-flux atom sources and broadens the applicability of recoil-sensitive interferometry to particles that remain difficult to trap and cool.

  3. Low momentum recoil detectors in CLAS12 at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Charles, Gabriel; CLAS Collaboration Collaboration

    2017-01-01

    Part of the experimental program in Hall B of the Jefferson Lab is dedicated to studying nucleon structure using DIS on nuclei and detecting low-momentum recoil particles in coincidence with the scattered electron. For this purpose, specially designed central detectors are required in place of the inner tracker of CLAS12 to detect particles with momenta below 100 MeV/c. We will present the status of the BONuS12 RTPC detector that will take data within the next 2 years. We will detail the main improvements made from the previous BONuS RTPC. In a second part, we will discuss another recoil experiment, called ALERT, that has been proposed to run in Hall B. The constraints being different, the recoil detector is based on a drift chamber and an array of scintillators. We will present the main differences between the two detectors and summarize the R&D performed to develop the ALERT detector.

  4. Nuclear Recoil Calibration of DarkSide-50

    NASA Astrophysics Data System (ADS)

    Edkins, Erin; DarkSide Collaboration

    2016-03-01

    DarkSide-50 dark matter experiment is a liquid argon time projection chamber (TPC) surrounded by a liquid scintillator active neutron veto, designed for the direct detection of Weakly Interacting Massive Particles (WIMPs). The success of such an experiment is dependent upon a detailed understanding of both the expected signal and backgrounds, achieved using radioactive calibration sources of known energies. Nuclear recoils provide a measurement of both the expected signal and the most dangerous background, as nuclear recoils from neutrons cannot be distinguished from a dark matter signal on an event-by-event basis in the TPC. In this talk, I will present the DS-50 calibration system, and analysis of the results of the calibration of DarkSide-50 to nuclear recoils using radioactive neutron sources. See also the DS-50 presentations by X. Xiang and G. Koh.

  5. Rupture and recoil of bent-core liquid crystal filaments.

    PubMed

    Salili, S M; Ostapenko, T; Kress, O; Bailey, C; Weissflog, W; Harth, K; Eremin, A; Stannarius, R; Jákli, A

    2016-05-25

    The recoil process of free-standing liquid crystal filaments is investigated experimentally and theoretically. We focus on two aspects, the contraction speed of the filament and a spontaneously formed undulation instability. At the moment of rupture, the filaments buckle similarly to the classical Euler buckling of elastic rods. The tip velocity decays with decreasing filament length. The wavelength of buckling affinely decreases with the retracting filament tip. The energy gain related to the decrease of the total length and surface area of the filaments is mainly dissipated by layer rearrangements during thickening of the fibre. A flow back into the meniscus is relevant only in the final stage of the recoil process. We introduce a model for the quantitative description of the filament retraction speed. The dynamics of this recoil behaviour may find relevance as a model for biology-related filaments.

  6. High-frequency Oscillations in Eyewalls of Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Li, Weibiao; Chen, Shumin

    2017-04-01

    High-frequency oscillations, with periods of about 2 hours, are first identified by applying wavelet analysis to observed minutely wind speeds around the eye and eyewall of tropical cyclones (TCs). Analysis of a model simulation of Typhoon Hagupit (2008) shows that the oscillations also occur in the intensity of TC, vertical motion, convergence activity and air density around the eyewall. Sequences of oscillations in these variables follow a certain order. In a typical cycle, the drop of density in the planetary boundary layer (PBL) is followed by an increase in the inward radial wind; this enhanced frictional convergence causes increase in density, followed by a decrease in the inward radial wind. The increase in convergence in the PBL causes increase of updraft at the top of the PBL, followed by high vertical velocity at high altitude of 8-10 km, then the increase of the maximum wind speed, and vice versa. Key words: tropical cyclone, high-frequency oscillations, eyewall, intensity

  7. Parametric Study of High Frequency Pulse Detonation Tubes

    NASA Technical Reports Server (NTRS)

    Cutler, Anderw D.

    2008-01-01

    This paper describes development of high frequency pulse detonation tubes similar to a small pulse detonation engine (PDE). A high-speed valve injects a charge of a mixture of fuel and air at rates of up to 1000 Hz into a constant area tube closed at one end. The reactants detonate in the tube and the products exit as a pulsed jet. High frequency pressure transducers are used to monitor the pressure fluctuations in the device and thrust is measured with a balance. The effects of injection frequency, fuel and air flow rates, tube length, and injection location are considered. Both H2 and C2H4 fuels are considered. Optimum (maximum specific thrust) fuel-air compositions and resonant frequencies are identified. Results are compared to PDE calculations. Design rules are postulated and applications to aerodynamic flow control and propulsion are discussed.

  8. High-frequency acoustic modes in an ionic liquid.

    PubMed

    Ribeiro, Mauro C C

    2013-09-21

    High-frequency collective dynamics of the ionic liquid 1-hexyl-3-methylimidazolium bromide, [C6C1im]Br, has been investigated by molecular dynamics simulations. Time correlation functions of mass current fluctuations were calculated for several wavevectors and the dispersion curves of excitations, ω(k), for longitudinal and transverse acoustic sound modes were obtained at different temperatures and pressures. Two different thermodynamic states have the same high-frequency sound velocity irrespective of the temperature provided that both have the same density. Partial time correlation functions of mass currents were calculated for the atoms belonging to the polar or the non-polar domains resulting from the heterogeneous structure of [C6C1im]Br. The partial correlation functions indicate that the polar domains are stiffer than the non-polar domains of the simulated ionic liquid.

  9. High-frequency oscillations and the neurobiology of schizophrenia.

    PubMed

    Uhlhaas, Peter J; Singer, Wolf

    2013-09-01

    Neural oscillations at low- and high-frequency ranges are a fundamental feature of large-scale networks. Recent evidence has indicated that schizophrenia is associated with abnormal amplitude and synchrony of oscillatory activity, in particular, at high (beta/gamma) frequencies. These abnormalities are observed during task-related and spontaneous neuronal activity which may be important for understanding the pathophysiology of the syndrome. In this paper, we shall review the current evidence for impaired beta/gamma-band oscillations and their involvement in cognitive functions and certain symptoms of the disorder. In the first part, we will provide an update on neural oscillations during normal brain functions and discuss underlying mechanisms. This will be followed by a review of studies that have examined high-frequency oscillatory activity in schizophrenia and discuss evidence that relates abnormalities of oscillatory activity to disturbed excitatory/inhibitory (E/I) balance. Finally, we shall identify critical issues for future research in this area.

  10. Clustered Desynchronization from High-Frequency Deep Brain Stimulation

    PubMed Central

    Wilson, Dan; Moehlis, Jeff

    2015-01-01

    While high-frequency deep brain stimulation is a well established treatment for Parkinson’s disease, its underlying mechanisms remain elusive. Here, we show that two competing hypotheses, desynchronization and entrainment in a population of model neurons, may not be mutually exclusive. We find that in a noisy group of phase oscillators, high frequency perturbations can separate the population into multiple clusters, each with a nearly identical proportion of the overall population. This phenomenon can be understood by studying maps of the underlying deterministic system and is guaranteed to be observed for small noise strengths. When we apply this framework to populations of Type I and Type II neurons, we observe clustered desynchronization at many pulsing frequencies. PMID:26713619

  11. High-Frequency Power Gain in the Mammalian Cochlea

    NASA Astrophysics Data System (ADS)

    Maoiléidigh, Dáibhid Ó.; Hudspeth, A. J.

    2011-11-01

    Amplification in the mammalian inner ear is thought to result from a nonlinear active process known as the cochlear amplifier. Although there is much evidence that outer hair cells (OHCs) play a central role in the cochlear amplifier, the mechanism of amplification remains uncertain. In non-mammalian ears hair bundles can perform mechanical work and account for the active process in vitro, yet in the mammalian cochlea membrane-based electromotility is required for amplification in vivo. A key issue is how OHCs conduct mechanical power amplification at high frequencies. We present a physical model of a segment of the mammalian cochlea that can amplify the power of external signals. In this representation both electromotility and active hair-bundle motility are required for mechanical power gain at high frequencies. We demonstrate how the endocochlear potential, the OHC resting potential, Ca2+ gradients, and ATP-fueled myosin motors serve as the energy sources underlying mechanical power gain in the cochlear amplifier.

  12. Analysis of winding losses in high frequency foil wound inductors

    SciTech Connect

    Kutkut, N.H.; Novotny, D.W.; Divan, D.M.; Yeow, E.

    1995-12-31

    The design of high power and high frequency foil wound inductors is not a straightforward task. At high frequencies, additional losses occur within the foil windings due to the eddy currents induced by skin, proximity, fringing and other ac effects. In addition, the winding structure greatly affects the distribution of losses within the windings. In this paper, the various loss mechanisms of a foil winding are analyzed and quantified. Both analytical and finite element analysis tools are utilized to investigate and understand the different loss mechanisms. The results show a strong correlation between the current and field distributions within the windings where the current is always attracted to the high field regions. By shaping and controlling the field distribution in a given design, the current distribution can be improved which results in an improvement in the winding losses.

  13. How High Frequency Trading Affects a Market Index

    PubMed Central

    Kenett, Dror Y.; Ben-Jacob, Eshel; Stanley, H. Eugene; gur-Gershgoren, Gitit

    2013-01-01

    The relationship between a market index and its constituent stocks is complicated. While an index is a weighted average of its constituent stocks, when the investigated time scale is one day or longer the index has been found to have a stronger effect on the stocks than vice versa. We explore how this interaction changes in short time scales using high frequency data. Using a correlation-based analysis approach, we find that in short time scales stocks have a stronger influence on the index. These findings have implications for high frequency trading and suggest that the price of an index should be published on shorter time scales, as close as possible to those of the actual transaction time scale. PMID:23817553

  14. High Frequency Resonant Electromagnetic Generation and Detection of Ultrasonic Waves

    NASA Astrophysics Data System (ADS)

    Kawashima, Katsuhiro; Wright, Oliver; Hyoguchi, Takao

    1994-05-01

    High frequency resonant mode electromagnetic ultrasonic generation and detection in metals is demonstrated at frequencies up to ˜150 MHz with various metal sheet samples. Using a unified theory of the generation and detection process, it is shown how various physical quantities can be measured. The sound velocity or thickness of the sheets can be derived from the resonant frequencies. At resonance the detected amplitude is inversely proportional to the ultrasonic attenuation of the sample, whereas the resonance half-width is proportional to this attenuation. We derive the ultrasonic attenuation coefficient from the half-width, and show how the grain size of the material can be probed. In addition we present results for thin bonded sheets, and show how a measure of the bonding or delamination can be obtained. This high frequency resonant method shows great promise for the non-destructive evaluation of thin sheets and coatings in the sub- 10-µm to 1-mm thickness range.

  15. High-frequency oscillation of the airway and chest wall.

    PubMed

    Fink, James B; Mahlmeister, Michael J

    2002-07-01

    High-frequency oscillation (HFO), applied to either the airway or chest wall, has been associated with changes in sputum attributes and clearance. The evolution of evidence, both in vitro and in vivo, supporting the use of HFO is reviewed. Devices that apply HFO to the airway range from the relatively simple mechanical Flutter and Acapella devices to the more complex Percussionaire Intrapercussive Ventilators. and the Hayek Oscillator are designed to provide high-frequency chest wall compression. Operation and use of these devices are described with examples of differentiation of device types by characterization of flows, and airway and esophageal pressures. Although HFO devices span a broad range of costs, they provide a reasonable therapeutic option to support secretion clearance for patients with cystic fibrosis.

  16. High frequency amplitude detector for GMI magnetic sensors.

    PubMed

    Asfour, Aktham; Zidi, Manel; Yonnet, Jean-Paul

    2014-12-19

    A new concept of a high-frequency amplitude detector and demodulator for Giant-Magneto-Impedance (GMI) sensors is presented. This concept combines a half wave rectifier, with outstanding capabilities and high speed, and a feedback approach that ensures the amplitude detection with easily adjustable gain. The developed detector is capable of measuring high-frequency and very low amplitude signals without the use of diode-based active rectifiers or analog multipliers. The performances of this detector are addressed throughout the paper. The full circuitry of the design is given, together with a comprehensive theoretical study of the concept and experimental validation. The detector has been used for the amplitude measurement of both single frequency and pulsed signals and for the demodulation of amplitude-modulated signals. It has also been successfully integrated in a GMI sensor prototype. Magnetic field and electrical current measurements in open- and closed-loop of this sensor have also been conducted.

  17. High Frequency Amplitude Detector for GMI Magnetic Sensors

    PubMed Central

    Asfour, Aktham; Zidi, Manel; Yonnet, Jean-Paul

    2014-01-01

    A new concept of a high-frequency amplitude detector and demodulator for Giant-Magneto-Impedance (GMI) sensors is presented. This concept combines a half wave rectifier, with outstanding capabilities and high speed, and a feedback approach that ensures the amplitude detection with easily adjustable gain. The developed detector is capable of measuring high-frequency and very low amplitude signals without the use of diode-based active rectifiers or analog multipliers. The performances of this detector are addressed throughout the paper. The full circuitry of the design is given, together with a comprehensive theoretical study of the concept and experimental validation. The detector has been used for the amplitude measurement of both single frequency and pulsed signals and for the demodulation of amplitude-modulated signals. It has also been successfully integrated in a GMI sensor prototype. Magnetic field and electrical current measurements in open- and closed-loop of this sensor have also been conducted. PMID:25536003

  18. Extracting cardiac myofiber orientations from high frequency ultrasound images

    NASA Astrophysics Data System (ADS)

    Qin, Xulei; Cong, Zhibin; Jiang, Rong; Shen, Ming; Wagner, Mary B.; Kirshbom, Paul; Fei, Baowei

    2013-03-01

    Cardiac myofiber plays an important role in stress mechanism during heart beating periods. The orientation of myofibers decides the effects of the stress distribution and the whole heart deformation. It is important to image and quantitatively extract these orientations for understanding the cardiac physiological and pathological mechanism and for diagnosis of chronic diseases. Ultrasound has been wildly used in cardiac diagnosis because of its ability of performing dynamic and noninvasive imaging and because of its low cost. An extraction method is proposed to automatically detect the cardiac myofiber orientations from high frequency ultrasound images. First, heart walls containing myofibers are imaged by B-mode high frequency (<20 MHz) ultrasound imaging. Second, myofiber orientations are extracted from ultrasound images using the proposed method that combines a nonlinear anisotropic diffusion filter, Canny edge detector, Hough transform, and K-means clustering. This method is validated by the results of ultrasound data from phantoms and pig hearts.

  19. High-frequency Broadband Modulations of Electroencephalographic Spectra

    PubMed Central

    Onton, Julie; Makeig, Scott

    2009-01-01

    High-frequency cortical potentials in electroencephalographic (EEG) scalp recordings have low amplitudes and may be confounded with scalp muscle activities. EEG data from an eyes-closed emotion imagination task were linearly decomposed using independent component analysis (ICA) into maximally independent component (IC) processes. Joint decomposition of IC log spectrograms into source- and frequency-independent modulator (IM) processes revealed three distinct classes of IMs that separately modulated broadband high-frequency (∼15–200 Hz) power of brain, scalp muscle, and likely ocular motor IC processes. Multi-dimensional scaling revealed significant but spatially complex relationships between mean broadband brain IM effects and the valence of the imagined emotions. Thus, contrary to prevalent assumption, unitary modes of spectral modulation of frequencies encompassing the beta, gamma, and high gamma frequency ranges can be isolated from scalp-recorded EEG data and may be differentially associated with brain sources and cognitive activities. PMID:20076775

  20. How high frequency trading affects a market index.

    PubMed

    Kenett, Dror Y; Ben-Jacob, Eshel; Stanley, H Eugene; Gur-Gershgoren, Gitit

    2013-01-01

    The relationship between a market index and its constituent stocks is complicated. While an index is a weighted average of its constituent stocks, when the investigated time scale is one day or longer the index has been found to have a stronger effect on the stocks than vice versa. We explore how this interaction changes in short time scales using high frequency data. Using a correlation-based analysis approach, we find that in short time scales stocks have a stronger influence on the index. These findings have implications for high frequency trading and suggest that the price of an index should be published on shorter time scales, as close as possible to those of the actual transaction time scale.

  1. Self-integrating inductive loop for measuring high frequency pulses

    NASA Astrophysics Data System (ADS)

    Rojas-Moreno, Mónica V.; Robles, Guillermo; Martínez-Tarifa, Juan M.; Sanz-Feito, Javier

    2011-08-01

    High frequency pulses can be measured by means of inductive sensors. The main advantage of these sensors consists of non-contact measurements that isolate and protect measuring equipment. The objective of this paper is to present the implementation of an inductive sensor for measuring rapidly varying currents. It consists of a rectangular loop with a resistor at its terminals. The inductive loop gives the derivative of the current according to Faraday's law and the resistor connected to the loop modifies the sensor's frequency response to obtain an output proportional to the current pulse. The self-integrating inductive sensor was validated with two sensors, a non-inductive resistor and a commercial high frequency current transformer. The results were compared to determine the advantages and drawbacks of the probe as an adequate inductive transducer.

  2. High-frequency microrheology reveals cytoskeleton dynamics in living cells

    NASA Astrophysics Data System (ADS)

    Rigato, Annafrancesca; Miyagi, Atsushi; Scheuring, Simon; Rico, Felix

    2017-08-01

    Living cells are viscoelastic materials, dominated by an elastic response on timescales longer than a millisecond. On shorter timescales, the dynamics of individual cytoskeleton filaments are expected to emerge, but active microrheology measurements on cells accessing this regime are scarce. Here, we develop high-frequency microrheology experiments to probe the viscoelastic response of living cells from 1 Hz to 100 kHz. We report the viscoelasticity of different cell types under cytoskeletal drug treatments. On previously inaccessible short timescales, cells exhibit rich viscoelastic responses that depend on the state of the cytoskeleton. Benign and malignant cancer cells revealed remarkably different scaling laws at high frequencies, providing a unique mechanical fingerprint. Microrheology over a wide dynamic range--up to the frequency characterizing the molecular components--provides a mechanistic understanding of cell mechanics.

  3. Extracting Cardiac Myofiber Orientations from High Frequency Ultrasound Images.

    PubMed

    Qin, Xulei; Cong, Zhibin; Jiang, Rong; Shen, Ming; Wagner, Mary B; Kishbom, Paul; Fei, Baowei

    2013-03-29

    Cardiac myofiber plays an important role in stress mechanism during heart beating periods. The orientation of myofibers decides the effects of the stress distribution and the whole heart deformation. It is important to image and quantitatively extract these orientations for understanding the cardiac physiological and pathological mechanism and for diagnosis of chronic diseases. Ultrasound has been wildly used in cardiac diagnosis because of its ability of performing dynamic and noninvasive imaging and because of its low cost. An extraction method is proposed to automatically detect the cardiac myofiber orientations from high frequency ultrasound images. First, heart walls containing myofibers are imaged by B-mode high frequency (>20 MHz) ultrasound imaging. Second, myofiber orientations are extracted from ultrasound images using the proposed method that combines a nonlinear anisotropic diffusion filter, Canny edge detector, Hough transform, and K-means clustering. This method is validated by the results of ultrasound data from phantoms and pig hearts.

  4. A high frequency transformer model for the EMTP

    SciTech Connect

    Morched, A.; Marti, L.; Ottevangers, J. )

    1993-07-01

    A model to simulate the high frequency behavior of a power transformer is presented. This model is based on the frequency characteristics of the transformer admittance matrix between its terminals over a given range of frequencies. The transformer admittance characteristics can be obtained from measurements or from detailed internal models based on the physical layout of the transformer. The elements of the nodal admittance matrix are approximated with rational functions consisting of real as well as complex conjugate poles and zeros. These approximations are realized in the form of an RLC network in a format suitable for direct use with EMTP. The high frequency transformer model can be used as a stand-alone linear model or as an add-on module of a more comprehensive model where iron core nonlinearities are represented in detail.

  5. High-frequency jet ventilation in a neonatal foal.

    PubMed

    Bain, F T; Brock, K A; Koterba, A M

    1988-04-01

    High-frequency jet ventilation was performed on a premature foal for respiratory difficulty attributable to in utero-acquired pneumonia. The procedure involves delivery of compressed gas through a small-bore cannula at frequencies up to 400 cycles/min. Ventilation settings of drive pressure, frequency, and FIO2 were varied to optimize PaO2 and PaCO2 values. The foal was ventilated with this equipment for 14 hours. Evidence of a favorable response to this method of ventilation was observed in the form of improvement in arterial blood gas values as well as the foal's attitude and degree of respiratory effort. High-frequency jet ventilation appears to be a useful method of ventilation for respiratory disease in neonatal foals; however, there remains no clear-cut advantage over conventional positive-pressure ventilation.

  6. Broadband high-frequency waves detected at dipolarization fronts

    NASA Astrophysics Data System (ADS)

    Yang, J.; Cao, J. B.; Fu, H. S.; Wang, T. Y.; Liu, W. L.; Yao, Z. H.

    2017-04-01

    Dipolarization front (DF) is a sharp boundary most probably separating the reconnection jet from the background plasma sheet. So far at this boundary, the observed waves are mainly in low-frequency range (e.g., magnetosonic waves and lower hybrid waves). Few high-frequency waves are observed in this region. In this paper, we report the broadband high-frequency wave emissions at the DF. These waves, having frequencies extending from the electron cyclotron frequency fce, up to the electron plasma frequency fpe, could contribute 10% to the in situ measurement of intermittent energy conversion at the DF layer. Their generation may be attributed to electron beams, which are simultaneously observed at the DF as well.

  7. Measurements of neutron energy using a recoil-proton telescope and a high-pressure ionization chamber.

    PubMed

    Folkard, M; Makrigiorgos, G; Roper, M J; Waker, A J; Michael, B D

    1989-04-01

    Two very different techniques for measuring the energy of neutrons in the energy range 0.1-10 MeV are presented and compared. A recoil-proton spectrometer is used to determine the energy spectra of neutrons produced by the d(4)-Be and p(4)-Be reactions down to the low-energy threshold of 0.7 MeV. The same radiation fields are also measured with a recently developed method using a high-pressure ionization chamber that can be used to determine the mean energy of the neutrons in a mixed neutron-gamma radiation field provided the gamma-ray absorbed dose fraction is determined independently. An intercomparison of the two methods shows that the high-pressure ionization chamber compares well and supplements the established recoil-proton spectrometer technique. The almost isotropic response of the chamber has enabled measurements to be made of the variation of mean neutron energy with depth in water for the two radiation fields.

  8. Microstrip antenna modeling and measurement at high frequencies

    SciTech Connect

    Bevensee, R.M.

    1986-04-30

    This report addresses the task C(i) of the Proposal for Microstrip Antenna Modeling and Measurement at High Frequencies by the writer, July 1985. The task is: Assess the advantages and disadvantages of the three computational approaches outlined in the Proposal, including any difficulties to be resolved and an estimate of the time required to implement each approach. The three approaches are (1) Finite Difference, (2) Sommerfeld-GTD-MOM, and (3) Surface Intergral Equations - MOM. These are discussed in turn.

  9. High-Frequency Propagation in the Ocean Waveguide

    DTIC Science & Technology

    2007-09-30

    High-Frequency Propagation in the Ocean Waveguide Michael B. Porter Heat , Light, and Sound Research, Inc. 3366 N. Torrey Pines Court, Suite 310...La Jolla, CA 92037 phone: (858) 457-0800 email: michael.porter@HLSResearch.com Katherine H. Kim Heat , Light, and Sound Research, Inc. 3366 N...ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Heat , Light

  10. High Frequency Acoustic Reflection and Transmission in Ocean Sediments

    DTIC Science & Technology

    2011-09-01

    scattering in ocean environments with special emphasis on propagation in shallow water waveguides and scattering from ocean sediments. 3 ) Development of...TYPE 3 . DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE High Frequency Acoustic Reflection and Transmission in Ocean Sediments...REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 2 3

  11. Automated composite ellipsoid modelling for high frequency GTD analysis

    NASA Technical Reports Server (NTRS)

    Sze, K. Y.; Rojas, R. G.; Klevenow, F. T.; Scheick, J. T.

    1991-01-01

    The preliminary results of a scheme currently being developed to fit a composite ellipsoid to the fuselage of a helicopter in the vicinity of the antenna location are discussed under the assumption that the antenna is mounted on the fuselage. The parameters of the close-fit composite ellipsoid would then be utilized as inputs into NEWAIR3, a code programmed in FORTRAN 77 for high frequency Geometrical Theory of Diffraction (GTD) Analysis of the radiation of airborne antennas.

  12. Design of 1 MHz Solid State High Frequency Power Supply

    NASA Astrophysics Data System (ADS)

    Parmar, Darshan; Singh, N. P.; Gajjar, Sandip; Thakar, Aruna; Patel, Amit; Raval, Bhavin; Dhola, Hitesh; Dave, Rasesh; Upadhay, Dishang; Gupta, Vikrant; Goswami, Niranjan; Mehta, Kush; Baruah, Ujjwal

    2017-04-01

    High Frequency Power supply (HFPS) is used for various applications like AM Transmitters, metallurgical applications, Wireless Power Transfer, RF Ion Sources etc. The Ion Source for a Neutral beam Injector at ITER-India uses inductively coupled power source at High Frequency (∼1 MHz). Switching converter based topology used to generate 1 MHz sinusoidal output is expected to have advantages on efficiency and reliability as compared to traditional RF Tetrode tubes based oscillators. In terms of Power Electronics, thermal and power coupling issues are major challenges at such a high frequency. A conceptual design for a 200 kW, 1 MHz power supply and a prototype design for a 600 W source been done. The prototype design is attempted with Class-E amplifier topology where a MOSFET is switched resonantly. The prototype uses two low power modules and a ferrite combiner to add the voltage and power at the output. Subsequently solution with Class-D H-Bridge configuration have been evaluated through simulation where module design is stable as switching device do not participate in resonance, further switching device voltage rating is substantially reduced. The rating of the modules is essentially driven by the maximum power handling capacity of the MOSFETs and ferrites in the combiner circuit. The output passive network including resonance tuned network and impedance matching network caters for soft switching and matches the load impedance to 50ohm respectively. This paper describes the conceptual design of a 200 kW high frequency power supply and experimental results of the prototype 600 W, 1 MHz source.

  13. Factors controlling high-frequency radiation from extended ruptures

    NASA Astrophysics Data System (ADS)

    Beresnev, Igor A.

    2017-04-01

    Small-scale slip heterogeneity or variations in rupture velocity on the fault plane are often invoked to explain the high-frequency radiation from earthquakes. This view has no theoretical basis, which follows, for example, from the representation integral of elasticity, an exact solution for the radiated wave field. The Fourier transform, applied to the integral, shows that the seismic spectrum is fully controlled by that of the source time function, while the distribution of final slip and rupture acceleration/deceleration only contribute to directivity. This inference is corroborated by the precise numerical computation of the full radiated field from the representation integral. We compare calculated radiation from four finite-fault models: (1) uniform slip function with low slip velocity, (2) slip function spatially modulated by a sinusoidal function, (3) slip function spatially modulated by a sinusoidal function with random roughness added, and (4) uniform slip function with high slip velocity. The addition of "asperities," both regular and irregular, does not cause any systematic increase in the spectral level of high-frequency radiation, except for the creation of maxima due to constructive interference. On the other hand, an increase in the maximum rate of slip on the fault leads to highly amplified high frequencies, in accordance with the prediction on the basis of a simple point-source treatment of the fault. Hence, computations show that the temporal rate of slip, not the spatial heterogeneity on faults, is the predominant factor forming the high-frequency radiation and thus controlling the velocity and acceleration of the resulting ground motions.

  14. Correlations and multi-affinity in high frequency financial datasets

    NASA Astrophysics Data System (ADS)

    Baviera, Roberto; Pasquini, Michele; Serva, Maurizio; Vergni, Davide; Vulpiani, Angelo

    2001-11-01

    In this paper we perform a quantitative check of long term correlations and multi-affinity in Deutsche Mark/US Dollar exchange rates using high frequency data. We show that the use of business time, i.e., the ranking of the quotes in the sequences, eliminates most of the seasonality in financial-time series, allowing a precise estimation of some return anomalies.

  15. High frequency scattering by a thin lossless dielectric slab

    NASA Technical Reports Server (NTRS)

    Burnside, W. D.; Burgener, K. W.

    1983-01-01

    A high frequency solution for scattering from a thin dielectric slab is developed, based on a modification of the uniform geometrical theory of diffraction solution for a half-plane, with the intention of developing a model for a windshield of a small private aircraft. Results of the theory are compared with experimental measurements and moment method calculations showing good agreement. Application of the solution is also addressed.

  16. Factors controlling high-frequency radiation from extended ruptures

    NASA Astrophysics Data System (ADS)

    Beresnev, Igor A.

    2017-09-01

    Small-scale slip heterogeneity or variations in rupture velocity on the fault plane are often invoked to explain the high-frequency radiation from earthquakes. This view has no theoretical basis, which follows, for example, from the representation integral of elasticity, an exact solution for the radiated wave field. The Fourier transform, applied to the integral, shows that the seismic spectrum is fully controlled by that of the source time function, while the distribution of final slip and rupture acceleration/deceleration only contribute to directivity. This inference is corroborated by the precise numerical computation of the full radiated field from the representation integral. We compare calculated radiation from four finite-fault models: (1) uniform slip function with low slip velocity, (2) slip function spatially modulated by a sinusoidal function, (3) slip function spatially modulated by a sinusoidal function with random roughness added, and (4) uniform slip function with high slip velocity. The addition of "asperities," both regular and irregular, does not cause any systematic increase in the spectral level of high-frequency radiation, except for the creation of maxima due to constructive interference. On the other hand, an increase in the maximum rate of slip on the fault leads to highly amplified high frequencies, in accordance with the prediction on the basis of a simple point-source treatment of the fault. Hence, computations show that the temporal rate of slip, not the spatial heterogeneity on faults, is the predominant factor forming the high-frequency radiation and thus controlling the velocity and acceleration of the resulting ground motions.

  17. Design and characterization of very high frequency pulse tube prototypes

    NASA Astrophysics Data System (ADS)

    Lopes, Diogo; Duval, Jean-Marc; Charles, Ivan; Butterworth, James; Trollier, Thierry; Tanchon, Julien; Ravex, Alain; Daniel, Christophe

    2012-06-01

    Weight and size are important features of a cryocooler when it comes to space applications. Given their reliability and low level of exported vibrations (due to the absence of moving cold parts), pulse tubes are good candidates for spatial purposes and their miniaturization has been the focus of many studies. We report on the design and performance of a small-scale very high frequency pulse tube prototype, modeled after two previous prototypes which were optimized with a numerical code.

  18. High frequency fluoroptic thermometry current sensing for weapon susceptibility testing

    SciTech Connect

    Cernosek, R.W.

    1988-01-01

    A high frequency current measurement technique for susceptibility testing is proposed. This technique uses a resistive element to produce a temperature change that is sensed by a fluoroptic thermometer. Laboratory testing has shown that RF currents as small as 1.5 mA are measureable for frequencies up to 10 GHz. Errors bounds in determining the current are 6 dB. 7 refs., 6 figs.

  19. High frequency fatigue testing of Udimet 700 at 1400 F

    NASA Technical Reports Server (NTRS)

    Conn, A. F.; Rudy, S. L.

    1972-01-01

    An investigation pertaining to the development of life prediction methods for materials subjected to high temperature creep/fatigue conditions is presented. High frequency (13.4 kHz) fatigue data were measured at 1400 F on specimens of the nickel-based alloy Udimet 700. Tests were conducted on the virgin material, as well as on specimens which had received prior exposures to high temperature, fatigue, and creep.

  20. High frequency fishbones excited by near perpendicular neutral beam injection

    SciTech Connect

    Zhou Deng

    2006-07-15

    The high frequency fishbone instability observed in experiments with near perpendicular neutral beam injection is interpreted as the ideal internal kink mode destabilized by circulating energetic ions. The mode frequency is close to the transit frequency of circulating ions. The beta value of the circulating ions is required to peak on the magnetic axis and the average value within the q=1 magnetic surface must exceed a critical value for the mode to grow up.

  1. Modeling high-frequency capacitance in SOI MOS capacitors

    NASA Astrophysics Data System (ADS)

    Łukasiak, Lidia; Jasiński, Jakub; Beck, Romuald B.; Ikraiam, Fawzi A.

    2016-12-01

    This paper presents a model of high frequency capacitance of a SOI MOSCAP. The capacitance in strong inversion is described with minority carrier redistribution in the inversion layer taken into account. The efficiency of the computational process is significantly improved. Moreover, it is suitable for the simulation of thin-film SOI structures. It may also be applied to the characterization of non-standard SOI MOSCAPS e.g. with nanocrystalline body.

  2. Resonant recoil in extreme mass ratio binary black hole mergers

    SciTech Connect

    Hirata, Christopher M.

    2011-05-15

    The inspiral and merger of a binary black hole system generally leads to an asymmetric distribution of emitted radiation, and hence a recoil of the remnant black hole directed opposite to the net linear momentum radiated. The recoil velocity is generally largest for comparable mass black holes and particular spin configurations, and approaches zero in the extreme mass ratio limit. It is generally believed that for extreme mass ratios {eta}<<1, the scaling of the recoil velocity is |V|{proportional_to}{eta}{sup 2}, where the proportionality coefficient depends on the spin of the larger hole and the geometry of the system (e.g. orbital inclination). The small recoil velocity is due to cancellations; while the fraction of the total binary mass radiated away in gravitational waves is O({eta}), most of this energy is emitted during the inspiral phase where the momentum radiated integrates to zero over an orbit. Here, we show that for low but nonzero inclination prograde orbits and very rapidly spinning large holes (spin parameter a{sub *}>0.9678) the inspiralling binary can pass through resonances where the orbit-averaged radiation-reaction force is nonzero. These resonance crossings lead to a new contribution to the kick, |V|{proportional_to}{eta}{sup 3/2}. For these configurations and sufficiently extreme mass ratios, this resonant recoil is dominant. While it seems doubtful that the resonant recoil will be astrophysically significant, its existence suggests caution when extrapolating the results of numerical kick results to extreme mass ratios and near-maximal spins.

  3. High frequency resolution terahertz time-domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Sangala, Bagvanth Reddy

    2013-12-01

    A new method for the high frequency resolution terahertz time-domain spectroscopy is developed based on the characteristic matrix method. This method is useful for studying planar samples or stack of planar samples. The terahertz radiation was generated by optical rectification in a ZnTe crystal and detected by another ZnTe crystal via electro-optic sampling method. In this new characteristic matrix based method, the spectra of the sample and reference waveforms will be modeled by using characteristic matrices. We applied this new method to measure the optical constants of air. The terahertz transmission through the layered systems air-Teflon-air-Quartz-air and Nitrogen gas-Teflon-Nitrogen gas-Quartz-Nitrogen gas was modeled by the characteristic matrix method. A transmission coefficient is derived from these models which was optimized to fit the experimental transmission coefficient to extract the optical constants of air. The optimization of an error function involving the experimental complex transmission coefficient and the theoretical transmission coefficient was performed using patternsearch algorithm of MATLAB. Since this method takes account of the echo waveforms due to reflections in the layered samples, this method allows analysis of longer time-domain waveforms giving rise to very high frequency resolution in the frequency-domain. We have presented the high frequency resolution terahertz time-domain spectroscopy of air and compared the results with the literature values. We have also fitted the complex susceptibility of air to the Lorentzian and Gaussian functions to extract the linewidths.

  4. Neuronal morphology generates high-frequency firing resonance.

    PubMed

    Ostojic, Srdjan; Szapiro, Germán; Schwartz, Eric; Barbour, Boris; Brunel, Nicolas; Hakim, Vincent

    2015-05-06

    The attenuation of neuronal voltage responses to high-frequency current inputs by the membrane capacitance is believed to limit single-cell bandwidth. However, neuronal populations subject to stochastic fluctuations can follow inputs beyond this limit. We investigated this apparent paradox theoretically and experimentally using Purkinje cells in the cerebellum, a motor structure that benefits from rapid information transfer. We analyzed the modulation of firing in response to the somatic injection of sinusoidal currents. Computational modeling suggested that, instead of decreasing with frequency, modulation amplitude can increase up to high frequencies because of cellular morphology. Electrophysiological measurements in adult rat slices confirmed this prediction and displayed a marked resonance at 200 Hz. We elucidated the underlying mechanism, showing that the two-compartment morphology of the Purkinje cell, interacting with a simple spiking mechanism and dendritic fluctuations, is sufficient to create high-frequency signal amplification. This mechanism, which we term morphology-induced resonance, is selective for somatic inputs, which in the Purkinje cell are exclusively inhibitory. The resonance sensitizes Purkinje cells in the frequency range of population oscillations observed in vivo.

  5. Asynchronous BCI control using high-frequency SSVEP.

    PubMed

    Diez, Pablo F; Mut, Vicente A; Avila Perona, Enrique M; Laciar Leber, Eric

    2011-07-14

    Steady-State Visual Evoked Potential (SSVEP) is a visual cortical response evoked by repetitive stimuli with a light source flickering at frequencies above 4 Hz and could be classified into three ranges: low (up to 12 Hz), medium (12-30) and high frequency (> 30 Hz). SSVEP-based Brain-Computer Interfaces (BCI) are principally focused on the low and medium range of frequencies whereas there are only a few projects in the high-frequency range. However, they only evaluate the performance of different methods to extract SSVEP. This research proposed a high-frequency SSVEP-based asynchronous BCI in order to control the navigation of a mobile object on the screen through a scenario and to reach its final destination. This could help impaired people to navigate a robotic wheelchair. There were three different scenarios with different difficulty levels (easy, medium and difficult). The signal processing method is based on Fourier transform and three EEG measurement channels. The research obtained accuracies ranging in classification from 65% to 100% with Information Transfer Rate varying from 9.4 to 45 bits/min. Our proposed method allows all subjects participating in the study to control the mobile object and to reach a final target without prior training.

  6. Effects of High-Frequency Torsional Impacts on Rock Drilling

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaohua; Tang, Liping; Tong, Hua

    2014-07-01

    High-frequency torsional impact drilling (HFTID) is a new technology which provides stable and efficient drilling. The goal of the present study is to investigate the effects of high-frequency torsional impacts on rock drilling. The impact parameters of the high-frequency torsional impact generator (HFTIG) are obtained by conducting a series of laboratory tests. The results of the tests reveal that the impact time decreases and the impact force increases with increasing impact frequency. The parameters are used as input for simulations of the rock crushing process, and a series of models for investigating the respective performance of HFTID and conventional drilling are developed. In addition, the Drucker-Prager criterion is used to describe the constitutive laws of the rock element, and the equivalent plastic strain criterion is adopted as the damage criterion. The models are run to simulate the dynamic rock crushing processes. The results of the simulations show that increase of the impact frequency results in a significant improvement in the rate of penetration (ROP), and a decrease in the life of the HFTIG. Considering the tool life and ROP, the optimum impact frequency of the HFTIG is 15 Hz. Finally, the performance of the HFTID technique is evaluated.

  7. High frequency estimation of 2-dimensional cavity scattering

    NASA Astrophysics Data System (ADS)

    Dering, R. S.

    1984-12-01

    This thesis develops a simple ray tracing approximation for the high frequency scattering from a two-dimensional cavity. Whereas many other cavity scattering algorithms are very time consuming, this method is very swift. The analytical development of the ray tracing approach is performed in great detail, and it is shown how the radar cross section (RCS) depends on the cavity's length and width along with the radar wave's angle of incidence. This explains why the cavity's RCS oscillates as a function of incident angle. The RCS of a two dimensional cavity was measured experimentally, and these results were compared to computer calculations based on the high frequency ray tracing theory. The comparison was favorable in the sense that angular RCS minima and maxima were exactly predicted even though accuracy of the RCS magnitude decreased for incident angles far off-axis. Overall, once this method is extended to three dimensions, the technique shows promise as a fast first approximation of high frequency cavity scattering.

  8. Design of matching layers for high-frequency ultrasonic transducers

    PubMed Central

    Fei, Chunlong; Ma, Jianguo; Chiu, Chi Tat; Williams, Jay A.; Fong, Wayne; Chen, Zeyu; Zhu, BenPeng; Xiong, Rui; Shi, Jing; Hsiai, Tzung K.; Shung, K. Kirk; Zhou, Qifa

    2015-01-01

    Matching the acoustic impedance of high-frequency (≥100 MHz) ultrasound transducers to an aqueous loading medium remains a challenge for fabricating high-frequency transducers. The traditional matching layer design has been problematic to establish high matching performance given requirements on both specific acoustic impedance and precise thickness. Based on both mass-spring scheme and microwave matching network analysis, we interfaced metal-polymer layers for the matching effects. Both methods hold promises for guiding the metal-polymer matching layer design. A 100 MHz LiNbO3 transducer was fabricated to validate the performance of the both matching layer designs. In the pulse-echo experiment, the transducer echo amplitude increased by 84.4% and its −6dB bandwidth increased from 30.2% to 58.3% comparing to the non-matched condition, demonstrating that the matching layer design method is effective for developing high-frequency ultrasonic transducers. PMID:26445518

  9. High-frequency audiometry: test reliability and procedural considerations.

    PubMed

    Stelmachowicz, P G; Beauchaine, K A; Kalberer, A; Kelly, W J; Jesteadt, W

    1989-02-01

    This study compared the reliability of a recently developed high-frequency audiometer (HFA) [Stevens et al., J. Acoust. Soc. Am. 81, 470-484 (1987)] with a less complicated system that uses supraaural earphones (Koss system). The new approach permits calibration on an individual basis, making it possible to express thresholds at high frequencies in dB SPL. Data obtained from 50 normal-hearing subjects, ranging in age from 10-60 years, were used to evaluate the effects on reliability of threshold variance, earpiece/earphone fitting variance, and the variance associated with the HFA calibration process. Without earpiece/earphone replacement, the reliability of thresholds for the two systems is similar. With replacement, the HFA showed poorer reliability than the Koss system above 11 kHz, largely due to errors in estimating the calibration function. HFA reliability is greater for subjects with valid calibration functions over the entire frequency range. When average correction factors are applied to the Koss data in an effort to convert threshold estimates to dB SPL, individual transfer functions are not represented accurately. Thus the benefit of being able to express thresholds at high frequencies in dB SPL must be weighed against the additional source of variability introduced by the HFA calibration process.

  10. Computing at the Dubna gas-filled recoil separator

    NASA Astrophysics Data System (ADS)

    Tsyganov, Yuri S.; Polyakov, Alexandr N.

    2006-03-01

    Simulation codes for the spectra of heavy implanted nuclei, applications for online data visualization and real time PC-based algorithms are considered. Special attention is paid to the application of real time techniques for radical suppression of background products in heavy-ion-induced nuclear reactions at the U-400 cyclotron of the Flerov Laboratory of Nuclear Reactions. The detection system of the Dubna gas-filled recoil separator (DGFRS) is also briefly described. Calculated heavy recoil spectra are compared with those measured in heavy-ion-induced nuclear reactions.

  11. Stopping Power of Au for Ti Using Elastic Recoil Technique

    SciTech Connect

    Linares, R.; Freire, J. A.; Ribas, R. V.; Medina, N. H.; Oliveira, J. R. B.; Seale, W. A.; Cybulska, E. W.; Wiedemann, K. T.; Allegro, P. R.; Toufen, D. L.

    2009-06-03

    The slowing down of heavy ions in matter is still not well understood especially at low energies (<0.5 MeV/u). In this contribution we present new experimental data for the stopping power of Au for Ti ions using an elastic recoil technique where a heavy-ion beam at low energies is produced by elastic scattering of an energetic primary beam imping on a thin target. Atoms from the target recoil at low energies. We compare our experimental data with previous data and with semi-empirical and theoretical models.

  12. Phosphorus geochemical cycling inferences from high frequency lake monitoring

    NASA Astrophysics Data System (ADS)

    Crockford, Lucy; Jordan, Philip; Taylor, David

    2013-04-01

    Freshwater bodies in Europe are required to return to good water quality status under the Water Framework Directive by 2015. A small inter-drumlin lake in the northeast of Ireland has been susceptible to eutrophic episodes and the presence of algal blooms during summer since annual monitoring began in 2002. While agricultural practice has been controlled by the implementation of the Nitrates Directive in 2006, the lake is failing to recover to good water quality status to meet with the Water Framework Directive objectives. Freshwaters in Ireland are regarded, in the main, as phosphorus (P) limited so identifying the sources of P possibly fuelling the algal blooms may provide an insight into how to improve water quality conditions. In a lake, these sources are divided between external catchment driven loads, as a result of farming and point sources, and P released from sediments made available to photic waters through internal lake mechanisms. High frequency sensors on data-sondes, installed on the lake in three locations, have provided chlorophyll a, redox potential, dissolved oxygen, temperature, pH, conductivity and turbidity data since March 2010. A data-sonde was installed in the hypolimnion to observe the change in lake conditions as P is released from lake sediments as a result of geochemical cycling with iron during anoxic periods. As compact high frequency sampling equipment for P analysis is still in its infancy for freshwaters, a proxy measurement of geochemical cycling in lakes would be useful to determine fully the extent of P contribution from sediments to the overall P load. Phosphorus was analysed once per month along with a number of other parameters and initial analysis of the high frequency data has shown changes in readings when known P release from lake sediments has occurred. Importantly, these data have shown when these P enriched hypolimnetic waters may be re-introduced to shallower waters in the photic zone, by changes in dissolved oxygen

  13. High-Frequency Excitation of a Plane Wake

    NASA Technical Reports Server (NTRS)

    Cain, Alan B.; Rogers, Michael M.

    2000-01-01

    In the early 1990's, Glezer and his co-workers at Georgia Tech made a startling discovery. They found that forcing at frequencies too high to directly affect the production scales led to a dramatic alteration in the development of a turbulent shear layer. An experimental study of this phenomenon is presented in Wiltse and Glezer. They used piezoelectric actuators located near the jet exit plane to force the shear layers of a square low-speed jet. The actuators were driven at a high frequency in the Kolmogorov inertial subrange, much higher than the frequencies associated with the large-scale motion (where the turbulent energy is produced and located) but much lower than those associated with the Kolmogorov scale (where the turbulent energy is dissipated). Measurements of the shear-layer turbulence showed that direct excitation of small-scale motion by high-frequency forcing led to an increase in the turbulent dissipation of more than an order of magnitude in the initial region of the shear layer! The turbulent dissipation gradually decreased with downstream distance but remained above the corresponding level for the unforced flow at all locations examined. The high-frequency forcing increased the turbulent kinetic energy in the initial region near the actuators, but the kinetic energy decreased quite rapidly with downstream distance, dropping to levels that were a small fraction of the level for the unforced case. Perhaps most importantly from the present standpoint, the high-frequency forcing significantly decreased the energy in the large-scale motion, increasingly so with downstream distance. Wiltse and Glezer interpreted this behavior as an enhanced transfer of energy from the large scales to the small scales. The initial work by Wiltse and Glezer has expanded into other applications. To explore the potential of high-frequency forcing for active acoustic suppression, in 1998 the first author proposed a set of experiments involving an edge tone shear layer and

  14. X-ray spectroscopy of a recoiling SMBH candidate

    NASA Astrophysics Data System (ADS)

    Predehl, Peter

    2008-09-01

    Recent numerical relativity simulations of coalescencing supermassive black hole (SMBH) binaries predict that SMBHs can receive kicks with velocities up to several thousand km/s due to anisotropic emission of gravitational waves. We have recently found the best candidate todate for such a recoiling SMBH (Komossa et al. 2008). We apply for a 25 ks ACIS-S exposure of this exceptional source.

  15. Elastic recoil detection (ERD) with extremely heavy ions

    NASA Astrophysics Data System (ADS)

    Forster, J. S.; Currie, P. J.; Davies, J. A.; Siegele, R.; Wallace, S. G.; Zelenitsky, D.

    1996-06-01

    Extremely heavy-ion beams such as 209Bi in elastic recoil detection (ERD) make ERD a uniquely valuable technique for thin-film analysis of elements with mass ≤ 100. We report ERD measurements of compositional analysis of dinosaur eggshells and bones. We also show the capability of the ERD technique on studies of thin-film, high-temperature superconductors.

  16. Epitaxial silicide formation on recoil-implanted substrates

    SciTech Connect

    Hashimoto, Shin; Egashira, Kyoko; Tanaka, Tomoya; Etoh, Ryuji; Hata, Yoshifumi; Tung, R. T.

    2005-01-15

    An epitaxy-on-recoil-implanted-substrate (ERIS) technique is presented. A disordered surface layer, generated by forward recoil implantation of {approx}0.7-3x10{sup 15} cm{sup -2} of oxygen during Ar plasma etching of surface oxide, is shown to facilitate the subsequent epitaxial growth of {approx}25-35-nm-thick CoSi{sub 2} layers on Si(100). The dependence of the epitaxial fraction of the silicide on the recoil-implantation parameters is studied in detail. A reduction in the silicide reaction rate due to recoil-implanted oxygen is shown to be responsible for the observed epitaxial formation, similar to mechanisms previously observed for interlayer-mediated growth techniques. Oxygen is found to remain inside the fully reacted CoSi{sub 2} layer, likely in the form of oxide precipitates. The presence of these oxide precipitates, with only a minor effect on the sheet resistance of the silicide layer, has a surprisingly beneficial effect on the thermal stability of the silicide layers. The agglomeration of ERIS-grown silicide layers on polycrystalline Si is significantly suppressed, likely from a reduced diffusivity due to oxygen in the grain boundaries. The implications of the present technique for the processing of deep submicron devices are discussed.

  17. Direct Measurement of Photon Recoil from a Levitated Nanoparticle

    NASA Astrophysics Data System (ADS)

    Jain, Vijay; Gieseler, Jan; Moritz, Clemens; Dellago, Christoph; Quidant, Romain; Novotny, Lukas

    2016-06-01

    The momentum transfer between a photon and an object defines a fundamental limit for the precision with which the object can be measured. If the object oscillates at a frequency Ω0 , this measurement backaction adds quanta ℏΩ0 to the oscillator's energy at a rate Γrecoil, a process called photon recoil heating, and sets bounds to coherence times in cavity optomechanical systems. Here, we use an optically levitated nanoparticle in ultrahigh vacuum to directly measure Γrecoil. By means of a phase-sensitive feedback scheme, we cool the harmonic motion of the nanoparticle from ambient to microkelvin temperatures and measure its reheating rate under the influence of the radiation field. The recoil heating rate is measured for different particle sizes and for different excitation powers, without the need for cavity optics or cryogenic environments. The measurements are in quantitative agreement with theoretical predictions and provide valuable guidance for the realization of quantum ground-state cooling protocols and the measurement of ultrasmall forces.

  18. Study of switching transients in high frequency converters

    NASA Astrophysics Data System (ADS)

    Zinger, Donald S.; Elbuluk, Malik E.; Lee, Tony

    1993-06-01

    As the semiconductor technologies progress rapidly, the power densities and switching frequencies of many power devices are improved. With the existing technology, high frequency power systems become possible. Use of such a system is advantageous in many aspects. A high frequency ac source is used as the direct input to an ac/ac pulse-density-modulation (PDM) converter. This converter is a new concept which employs zero voltage switching techniques. However, the development of this converter is still in its infancy stage. There are problems associated with this converter such as a high on-voltage drop, switching transients, and zero-crossing detecting. Considering these problems, the switching speed and power handling capabilities of the MOS-Controlled Thyristor (MCT) makes the device the most promising candidate for this application. A complete insight of component considerations for building an ac/ac PDM converter for a high frequency power system is addressed. A power device review is first presented. The ac/ac PDM converter requires switches that can conduct bi-directional current and block bi-directional voltage. These bi-directional switches can be constructed using existing power devices. Different bi-directional switches for the converter are investigated. Detailed experimental studies of the characteristics of the MCT under hard switching and zero-voltage switching are also presented. One disadvantage of an ac/ac converter is that turn-on and turn-off of the switches has to be completed instantaneously when the ac source is at zero voltage. Otherwise shoot-through current or voltage spikes can occur which can be hazardous to the devices. In order for the devices to switch softly in the safe operating area even under non-ideal cases, a unique snubber circuit is used in each bi-directional switch. Detailed theory and experimental results for circuits using these snubbers are presented.

  19. Study of switching transients in high frequency converters

    NASA Technical Reports Server (NTRS)

    Zinger, Donald S.; Elbuluk, Malik E.; Lee, Tony

    1993-01-01

    As the semiconductor technologies progress rapidly, the power densities and switching frequencies of many power devices are improved. With the existing technology, high frequency power systems become possible. Use of such a system is advantageous in many aspects. A high frequency ac source is used as the direct input to an ac/ac pulse-density-modulation (PDM) converter. This converter is a new concept which employs zero voltage switching techniques. However, the development of this converter is still in its infancy stage. There are problems associated with this converter such as a high on-voltage drop, switching transients, and zero-crossing detecting. Considering these problems, the switching speed and power handling capabilities of the MOS-Controlled Thyristor (MCT) makes the device the most promising candidate for this application. A complete insight of component considerations for building an ac/ac PDM converter for a high frequency power system is addressed. A power device review is first presented. The ac/ac PDM converter requires switches that can conduct bi-directional current and block bi-directional voltage. These bi-directional switches can be constructed using existing power devices. Different bi-directional switches for the converter are investigated. Detailed experimental studies of the characteristics of the MCT under hard switching and zero-voltage switching are also presented. One disadvantage of an ac/ac converter is that turn-on and turn-off of the switches has to be completed instantaneously when the ac source is at zero voltage. Otherwise shoot-through current or voltage spikes can occur which can be hazardous to the devices. In order for the devices to switch softly in the safe operating area even under non-ideal cases, a unique snubber circuit is used in each bi-directional switch. Detailed theory and experimental results for circuits using these snubbers are presented. A current regulated ac/ac PDM converter built using MCT's and IGBT's is

  20. Cholinergic mechanisms of high-frequency stimulation in entopeduncular nucleus

    PubMed Central

    Luo, Feng

    2015-01-01

    Chronic, high-frequency (>100 Hz) electrical stimulation, known as deep brain stimulation (DBS), of the internal segment of the globus pallidus (GPi) is a highly effective therapy for Parkinson's disease (PD) and dystonia. Despite some understanding of how it works acutely in PD models, there remain questions about its mechanisms of action. Several hypotheses have been proposed, such as depolarization blockade, activation of inhibitory synapses, depletion of neurotransmitters, and/or disruption/alteration of network oscillations. In this study we investigated the cellular mechanisms of high-frequency stimulation (HFS) in entopeduncular nucleus (EP; rat equivalent of GPi) neurons using whole cell patch-clamp recordings. We found that HFS applied inside the EP nucleus induced a prolonged afterdepolarization that was dependent on stimulation frequency, pulse duration, and current amplitude. The high frequencies (>100 Hz) and pulse widths (>0.15 ms) used clinically for dystonia DBS could reliably induce these afterdepolarizations, which persisted under blockade of ionotropic glutamate (kynurenic acid, 2 mM), GABAA (picrotoxin, 50 μM), GABAB (CGP 55845, 1 μM), and acetylcholine nicotinic receptors (DHβE, 2 μM). However, this effect was blocked by atropine (2 μM; nonselective muscarinic antagonist) or tetrodotoxin (0.5 μM). Finally, the muscarinic-dependent afterdepolarizations were sensitive to Ca2+-sensitive nonspecific cationic (CAN) channel blockade. Hence, these data suggest that muscarinic receptor activation during HFS can lead to feedforward excitation through the opening of CAN channels. This study for the first time describes a cholinergic mechanism of HFS in EP neurons and provides new insight into the underlying mechanisms of DBS. PMID:26334006

  1. High Frequency Ground Motion from Finite Fault Rupture Simulations

    NASA Astrophysics Data System (ADS)

    Crempien, Jorge G. F.

    There are many tectonically active regions on earth with little or no recorded ground motions. The Eastern United States is a typical example of regions with active faults, but with low to medium seismicity that has prevented sufficient ground motion recordings. Because of this, it is necessary to use synthetic ground motion methods in order to estimate the earthquake hazard a region might have. Ground motion prediction equations for spectral acceleration typically have geometric attenuation proportional to the inverse of distance away from the fault. Earthquakes simulated with one-dimensional layered earth models have larger geometric attenuation than the observed ground motion recordings. We show that as incident angles of rays increase at welded boundaries between homogeneous flat layers, the transmitted rays decrease in amplitude dramatically. As the receiver distance increases away from the source, the angle of incidence of up-going rays increases, producing negligible transmitted ray amplitude, thus increasing the geometrical attenuation. To work around this problem we propose a model in which we separate wave propagation for low and high frequencies at a crossover frequency, typically 1Hz. The high-frequency portion of strong ground motion is computed with a homogeneous half-space and amplified with the available and more complex one- or three-dimensional crustal models using the quarter wavelength method. We also make use of seismic coda energy density observations as scattering impulse response functions. We incorporate scattering impulse response functions into our Green's functions by convolving the high-frequency homogeneous half-space Green's functions with normalized synthetic scatterograms to reproduce scattering physical effects in recorded seismograms. This method was validated against ground motion for earthquakes recorded in California and Japan, yielding results that capture the duration and spectral response of strong ground motion.

  2. Engineering Graphene Conductivity for Flexible and High-Frequency Applications.

    PubMed

    Samuels, Alexander J; Carey, J David

    2015-10-14

    Advances in lightweight, flexible, and conformal electronic devices depend on materials that exhibit high electrical conductivity coupled with high mechanical strength. Defect-free graphene is one such material that satisfies both these requirements and which offers a range of attractive and tunable electrical, optoelectronic, and plasmonic characteristics for devices that operate at microwave, terahertz, infrared, or optical frequencies. Essential to the future success of such devices is therefore the ability to control the frequency-dependent conductivity of graphene. Looking to accelerate the development of high-frequency applications of graphene, here we demonstrate how readily accessible and processable organic and organometallic molecules can efficiently dope graphene to carrier densities in excess of 10(13) cm(-2) with conductivities at gigahertz frequencies in excess of 60 mS. In using the molecule 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane (F2-HCNQ), a high charge transfer (CT) of 0.5 electrons per adsorbed molecule is calculated, resulting in p-type doping of graphene. n-Type doping is achieved using cobaltocene and the sulfur-containing molecule tetrathiafulvalene (TTF) with a CT of 0.41 and 0.24 electrons donated per adsorbed molecule, respectively. Efficient CT is associated with the interaction between the π electrons present in the molecule and in graphene. Calculation of the high-frequency conductivity shows dispersion-less behavior of the real component of the conductivity over a wide range of gigahertz frequencies. Potential high-frequency applications in graphene antennas and communications that can exploit these properties and the broader impacts of using molecular doping to modify functional materials that possess a low-energy Dirac cone are also discussed.

  3. High-Frequency Wave Measurements in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Bjorkqvist, J. V.; Kahma, K. K.; Pettersson, H.; Drennan, W. M.

    2016-02-01

    The high-frequency part of the wave field is essential for the understanding of air-sea exchange related processes and the turbulent energy dissipation of breaking waves. The quantification of the dimensionless spectra will aid wave model development and contribute to a better understanding of the fundamental laws governing the evolution of wind driven waves. However, typical wave observation devices, such as wave buoys, are limited to observing frequencies under e.g. 0.6 Hz. Dedicated experiments with devices suitable for high-frequency measurements are, in comparison, rare.We have made high-frequency wave measurements with capacitive wave staffs from RV Aranda. Air turbulence and wind speed measurements are also available and a full motion correction was applied to all measurements. A frequency rage up to 2-3 Hz is enough to study the tail of the wave spectra even during its early development. The unusually high sampling frequency of 200 Hz guarantees that spurious spectral shapes that could be the joint effect of noise and the anti-aliasing filter can be excluded. Directional measurements were made using four wave staffs located 15 or 50 cm apart in the grid.The mobility of the research vessel has enabled measurements in a wide variety of conditions from the Baltic Proper to the irregular Finnish coastal archipelagos. The aim is to determine the conditions and frequency ranges when the shape of the dimensionless spectra is wind dependent. Especially, it's still not clear whether the use of the wind speed or the friction velocity as the scaling parameter produces better results, or where the transition to the Phillips spectra takes place. The directional measurements can shed light on theories that use the directional spread of the two-dimensional spectrum to explain the shape of the one-dimensional spectrum.

  4. Acoustic trapping with a high frequency linear phased array.

    PubMed

    Zheng, Fan; Li, Ying; Hsu, Hsiu-Sheng; Liu, Changgeng; Tat Chiu, Chi; Lee, Changyang; Ham Kim, Hyung; Shung, K Kirk

    2012-11-19

    A high frequency ultrasonic phased array is shown to be capable of trapping and translating microparticles precisely and efficiently, made possible due to the fact that the acoustic beam produced by a phased array can be both focused and steered. Acoustic manipulation of microparticles by a phased array is advantageous over a single element transducer since there is no mechanical movement required for the array. Experimental results show that 45 μm diameter polystyrene microspheres can be easily and accurately trapped and moved to desired positions by a 64-element 26 MHz phased array.

  5. High-Frequency-Induced Cathodic Breakdown during Plasma Electrolytic Oxidation

    NASA Astrophysics Data System (ADS)

    Nominé, A.; Nominé, A. V.; Braithwaite, N. St. J.; Belmonte, T.; Henrion, G.

    2017-09-01

    The present communication shows the possibility of observing microdischarges under cathodic polarization during plasma electrolytic oxidation at high frequency. Cathodic microdischarges can ignite beyond a threshold frequency found close to 2 kHz. The presence (respectively, absence) of an electrical double layer is put forward to explain how the applied voltage can be screened, which therefore prevents (respectively, promotes) the ignition of a discharge. Interestingly, in the conditions of the present study, the electrical double layer requires between 175 and 260 μ s to form. This situates the expected threshold frequency between 1.92 and 2.86 kHz, which is in good agreement with the value obtained experimentally.

  6. High-frequency nonreciprocal reflection from magnetic films with overlayers

    SciTech Connect

    Wang, Ying; Nie, Yan; Camley, R. E.

    2013-11-14

    We perform a theoretical study of the nonreciprocal reflection of high-frequency microwave radiation from ferromagnetic films with thin overlayers. Reflection from metallic ferromagnetic films is always near unity and shows no nonreciprocity. In contrast, reflection from a structure which has a dielectric overlayer on top of a film composed of insulated ferromagnetic nanoparticles or nanostructures can show significant nonreciprocity in the 75–80 GHz frequency range, a very high value. This can be important for devices such as isolators or circulators.

  7. ZCS High Frequency Inverter for Aluminum Vessel Induction Heating

    NASA Astrophysics Data System (ADS)

    Ogiwara, Hiroyuki; Nakaoka, Mutsuo

    Recent induction cooking apparatus are utilized for induction heating of ferromagnetic materials at 20-50kHz with a high efficiency. They can not, however, be applied for non-magnetic materials such as aluminum vessels. Here, we present a voltage-clamp reverse conducting ZCS high frequency inverter of half bridge type for induction heating of an aluminum vessel. The switching devices utilized for this inverter are SITs and its operating frequency is determined as 200kHz. This paper describes its circuit constitution and the obtained experimental results from a practical point of view.

  8. Material considerations for high frequency, high power capacitors

    NASA Technical Reports Server (NTRS)

    White, W.; Galperin, I.

    1983-01-01

    Dielectric materials chosen for use in this high frequency, high power capacitor must endure hard vacuum conditions, high currents (up to 125 A rms), and frequencies up to 40 kHz. Temperature requirements for this type of capacitor are that capacitor operation must be efficient up to 125 C. A more stringent requirement for the sold dielectric is that the temperature coefficient of dissipation factor should indicate self stabilization well below 125 C. In addition, the dielectric temperature coefficient of capacitance should be negative.

  9. High frequency columnar silicon microresonators for mass detection

    SciTech Connect

    Kehrbusch, J.; Ilin, E. A.; Hullin, M.; Oesterschulze, E.

    2008-07-14

    A simple but effective technological scheme for the fabrication of high frequency silicon columnar microresonators is presented. With the proposed technique the dimensions of the microresonators are controlled on a scale of at least 1 {mu}m. Characterization of the mechanical properties of silicon columns gave resonant frequencies of the lowest flexural mode of 3-7 MHz with quality factors of up to 2500 in air and {approx}8800 under vacuum condition. Columnar microresonators were operated as mass balance with a sensitivity of 1 Hz/fg. A mass detection limit of 25 fg was deduced from experiments.

  10. Acoustic trapping with a high frequency linear phased array

    PubMed Central

    Zheng, Fan; Li, Ying; Hsu, Hsiu-Sheng; Liu, Changgeng; Tat Chiu, Chi; Lee, Changyang; Ham Kim, Hyung; Shung, K. Kirk

    2012-01-01

    A high frequency ultrasonic phased array is shown to be capable of trapping and translating microparticles precisely and efficiently, made possible due to the fact that the acoustic beam produced by a phased array can be both focused and steered. Acoustic manipulation of microparticles by a phased array is advantageous over a single element transducer since there is no mechanical movement required for the array. Experimental results show that 45 μm diameter polystyrene microspheres can be easily and accurately trapped and moved to desired positions by a 64-element 26 MHz phased array. PMID:23258939

  11. Nonlinear interactions in planar jet flow with high frequency excitation

    NASA Astrophysics Data System (ADS)

    Kreutzfeldt, Timothy

    An experimental active flow control study was conducted involving excitation of a tabletop planar turbulent jet with a high frequency piezoelectric actuator. The excitation frequencies considered corresponded to the dissipative subrange of turbulent kinetic energy and were orders of magnitude greater than classical shear layer instability modes. Single-wire and dual-wire hot wire probes were used to determine how excitation induces alterations to bulk flow quantities as well as nonlinear interactions. Differences in flow receptivity to high frequency excitation were investigated by varying the development length of the turbulent jet at a Reynolds number of 8,700 and Strouhal number of 21.3. Excitation of developed turbulent flow yielded larger increases in the energy dissipation rate and higher magnitude velocity power spectrum peaks at the forcing frequency than undeveloped turbulent flow. Further tests with excitation of reduced mean velocity flow at a Reynolds number of 6,600 and a Strouhal number of 27.8 demonstrated that high frequency forcing resulted in transfer of energy from large to small scales in the turbulent kinetic energy spectrum. This phenomenon appeared to support past literature that indicated that the mechanics of high frequency forcing are fundamentally different from conventional instability-based forcing. Theoretical arguments are presented to support these experimental observations where it is shown that coupling between the applied forcing and background turbulent fluctuations is enhanced. An eddy viscosity model first proposed under the assumption of instability-based forcing was shown to be an effective approximation for the experimental measurements presented here in which the flow was forced directly at turbulence scales. Dimensional analysis of the coupling between the induced oscillations and the turbulent fluctuations supported experimental findings that receptivity to excitation was increased for forced flow with higher turbulent

  12. Accuracy of High Frequency Maximum Usable Frequencies (MUF) Prediction.

    DTIC Science & Technology

    1981-09-15

    shown in Figure 35 to be rat er constant at about 20 percent for MINIMUF-3.5. Whereas for HFMUFES 4 it is above 30 per- 57 CL - a / C 4L 4’ w I Z. LL U...Predictin2 the Performance of High-Frequency Skywave Telecomunication Systems (the use of the HFMJFES 4 Program), by GW Haydon, M Leftin , and R Rosich...in Ionospheric Maping by Numerical Methods, by WB Jones, RP Graham, and M Leftin , 12 May 1966. (Also Environmental Science Services Administration

  13. High frequency drift instabilities in a dusty plasma

    NASA Technical Reports Server (NTRS)

    Rosenberg, M.; Krall, N. A.

    1994-01-01

    High frequency drift instabilities with omega(sub ce) much greater than omega which is greater than omega(sub ci) are investigated in a dusty magnetized plasma in which locally there is an electron density gradient which is opposite in sign to a dust density gradient. Two different equilibria are considered, characterized by rho(sub d) greater than L(sub d) and less than L(sub d), where rho(sub d) is the dust gyroradius and L(sub nd) is the dust density scale length. Possible application to Saturn's F-ring is discussed.

  14. A fast directional algorithm for high-frequency electromagnetic scattering

    SciTech Connect

    Tsuji, Paul; Ying Lexing

    2011-06-20

    This paper is concerned with the fast solution of high-frequency electromagnetic scattering problems using the boundary integral formulation. We extend the O(N log N) directional multilevel algorithm previously proposed for the acoustic scattering case to the vector electromagnetic case. We also detail how to incorporate the curl operator of the magnetic field integral equation into the algorithm. When combined with a standard iterative method, this results in an almost linear complexity solver for the combined field integral equations. In addition, the butterfly algorithm is utilized to compute the far field pattern and radar cross section with O(N log N) complexity.

  15. Investigation of iron cobalt nanocomposites for high frequency applications

    NASA Astrophysics Data System (ADS)

    Miller, Kelsy J.

    FeCo-based nanocomposite soft magnetic materials were developed in collaboration with Magnetics, Division of Spang and Co., for high frequency and high temperature application. Excellent soft magnetic properties include: low coercivity, high permeability, low energy losses, etc. These and large saturation inductions make these alloys attractive for fundamental studies and industrial applications. In this thesis, nanocrystalline composites will be developed from amorphous precursors for applications in two frequency regimes: 1) High frequency (0.01-30 MHz) such as high temperature power inductors, pulsed power transformers, and radio frequency (rf) magnetic heating; and 2) Ultra high frequency (30 MHz - 30 GHz) for radio frequency materials and electromagnetic interference (EMI) or radio frequency interference (RFI) absorption. New nanocomposites with higher saturation induction and high-temperature stability were developed with reduced glass forming elements such as Zr, Nb, Si and B. The amounts of the magnetic transition metals and early transition metal growth inhibitors were varied to determine trade-offs between higher inductions and fine microstructures and consequently low magnetic losses. Alloys having (Fe1-xCox)80+y+zNb4-y B13-zSi2Cu1 (25 ≤ x ≤ 50 and y = 0-4 and z = 0-3) nominal compositions were cast using planar flow casting (PFC) at Magnetics. Technical magnetic properties: permeability, maximum induction, remanence ratio, coercive field and high frequency magnetic losses as a function of composition and annealing temperature are reported after primary crystallization for 1 hr in a transverse magnetic field (TMF). Of note is the development of inductor cores with maximum inductions in excess of 1.76 T and 1.67 T in cores that exhibit power losses comparable with state of the art commercial soft magnetic alloys. For application in EMI/RFI absorption, FeCo-based alloys have the largest saturation induction and a tunable magnetic anisotropy which may

  16. Kapitza thermal resistance studied by high-frequency photothermal radiometry

    SciTech Connect

    Horny, Nicolas; Chirtoc, Mihai; Hamaoui, Georges; Fleming, Austin; Ban, Heng

    2016-07-18

    Kapitza thermal resistance is determined using high-frequency photothermal radiometry (PTR) extended for modulation up to 10 MHz. Interfaces between 50 nm thick titanium coatings and silicon or stainless steel substrates are studied. In the used configuration, the PTR signal is not sensitive to the thermal conductivity of the film nor to its optical absorption coefficient, thus the Kapitza resistance is directly determined from single thermal parameter fits. Results of thermal resistances show the significant influence of the nature of the substrate, as well as of the presence of free electrons at the interface.

  17. High frequency SAW devices based on third harmonic generation.

    PubMed

    Le Brizoual, L; Elmazria, O; Sarry, F; El Hakiki, M; Talbi, A; Alnot, P

    2006-12-01

    We demonstrate the third harmonic generation in a ZnO/Si layered structure to obtain high frequency SAW devices. This configuration eliminates the need of high lithography resolution and allows easy integration of such devices and electronics on the same wafer. A theoretical study was carried out for the determination of the phase velocity and the electromechanical coupling coefficient (K(2)) dispersion curves of the surface acoustic waves. These results are also in agreement with those measured on a SAW filter designed for the third harmonic generation and the operating frequency is up to 2468 MHz.

  18. High frequency properties of a CNT-based nanorelay

    NASA Astrophysics Data System (ADS)

    Jonsson, L. M.; Axelsson, S.; Nord, T.; Viefers, S.; Kinaret, J. M.

    2004-11-01

    We have theoretically investigated the high frequency properties of a carbon-nanotube-based three-terminal nanoelectromechanical relay. The intrinsic mechanical frequency of the relay is in the GHz regime, and the electromechanical coupling shows a non-linear resonant behaviour in this frequency range. We discuss how these resonances may be detected and show that the resonance frequencies can be tuned by the bias voltage. Also, we show that the influence of external electromagnetic fields on the relay is negligible at all frequencies.

  19. HIGH FREQUENCY ULTRASOUND OF ARMOR-GRADE ALUMINA CERAMICS

    SciTech Connect

    Bottiglieri, S.; Haber, R. A.

    2009-03-03

    Different lots of high density, commercial, armor-grade alumina (Al{sub 2}O{sub 3}) were tested using high frequency ultrasound in order to determine any correlation between measured properties and ballistic performance. C-scan images were taken using a 15 MHz ultrasonic transducer in order to form attenuation coefficient and elastic property maps. These samples were further characterized by using quantitative analysis. The results indicate that attenuation coefficient values appear to have the strongest correlation, of every property measured, to ballistic classifications.

  20. Fluctuation patterns in high-frequency financial asset returns

    NASA Astrophysics Data System (ADS)

    Preis, T.; Paul, W.; Schneider, J. J.

    2008-06-01

    We introduce a new method for quantifying pattern-based complex short-time correlations of a time series. Our correlation measure is 1 for a perfectly correlated and 0 for a random walk time series. When we apply this method to high-frequency time series data of the German DAX future, we find clear correlations on short time scales. In order to subtract trivial autocorrelation parts from the pattern conformity, we introduce a simple model for reproducing the antipersistent regime and use alternatively level 1 quotes. When we remove the pattern conformity of this stochastic process from the original data, remaining pattern-based correlations can be observed.

  1. Motor monitoring method and apparatus using high frequency current components

    DOEpatents

    Casada, D.A.

    1996-05-21

    A motor current analysis method and apparatus for monitoring electrical-motor-driven devices are disclosed. The method and apparatus utilize high frequency portions of the motor current spectra to evaluate the condition of the electric motor and the device driven by the electric motor. The motor current signal produced as a result of an electric motor is monitored and the low frequency components of the signal are removed by a high-pass filter. The signal is then analyzed to determine the condition of the electrical motor and the driven device. 16 figs.

  2. Motor monitoring method and apparatus using high frequency current components

    DOEpatents

    Casada, Donald A.

    1996-01-01

    A motor current analysis method and apparatus for monitoring electrical-motor-driven devices. The method and apparatus utilize high frequency portions of the motor current spectra to evaluate the condition of the electric motor and the device driven by the electric motor. The motor current signal produced as a result of an electric motor is monitored and the low frequency components of the signal are removed by a high-pass filter. The signal is then analyzed to determine the condition of the electrical motor and the driven device.

  3. Explanation of persistent high frequency density structure in coalesced bunches

    SciTech Connect

    Jackson, Gerald P.

    1988-07-01

    It has been observed that after the Main Ring rf manipulation of coalescing (where 5 to 13 primary bunches are transferred into a single rf bucket) the new secondary bunch displays evidence of high frequency density structure superimposed on the approximately Gaussian longitudinal bunch length distribution. This structure is persistent over a period of many seconds (hundreds of synchrotron oscillation periods). With the help of multiparticle simulation programs, an explanation of this phenomenon is given in terms of single particle longitudinal phase space dynamics. No coherent effects need be taken into account. 6 refs., 10 figs.

  4. Material considerations for high frequency, high power capacitors

    NASA Astrophysics Data System (ADS)

    White, W.; Galperin, I.

    1983-10-01

    Dielectric materials chosen for use in this high frequency, high power capacitor must endure hard vacuum conditions, high currents (up to 125 A rms), and frequencies up to 40 kHz. Temperature requirements for this type of capacitor are that capacitor operation must be efficient up to 125 C. A more stringent requirement for the sold dielectric is that the temperature coefficient of dissipation factor should indicate self stabilization well below 125 C. In addition, the dielectric temperature coefficient of capacitance should be negative.

  5. The mechanics of elastic loading and recoil in anuran jumping.

    PubMed

    Astley, Henry C; Roberts, Thomas J

    2014-12-15

    Many animals use catapult mechanisms to produce extremely rapid movements for escape or prey capture, resulting in power outputs far beyond the limits of muscle. In these catapults, muscle contraction loads elastic structures, which then recoil to release the stored energy extremely rapidly. Many arthropods employ anatomical 'catch mechanisms' to lock the joint in place during the loading period, which can then be released to allow joint motion via elastic recoil. Jumping vertebrates lack a clear anatomical catch, yet face the same requirement to load the elastic structure prior to movement. There are several potential mechanisms to allow loading of vertebrate elastic structures, including the gravitational load of the body, a variable mechanical advantage, and moments generated by the musculature of proximal joints. To test these hypothesized mechanisms, we collected simultaneous 3D kinematics via X-ray Reconstruction of Moving Morphology (XROMM) and single-foot forces during the jumps of three Rana pipiens. We calculated joint mechanical advantage, moment and power using inverse dynamics at the ankle, knee, hip and ilio-sacral joints. We found that the increasing proximal joint moments early in the jump allowed for high ankle muscle forces and elastic pre-loading, and the subsequent reduction in these moments allowed the ankle to extend using elastic recoil. Mechanical advantage also changed throughout the jump, with the muscle contracting against a poor mechanical advantage early in the jump during loading and a higher mechanical advantage late in the jump during recoil. These 'dynamic catch mechanisms' serve to resist joint motion during elastic loading, then allow it during elastic recoil, functioning as a catch mechanism based on the balance and orientation of forces throughout the limb rather than an anatomical catch.

  6. The Differential Cross Section and Lambda Recoil Polarization From gamma d to K0 Lambda( p)

    NASA Astrophysics Data System (ADS)

    Compton, Nicholas

    Presented is the analysis of the differential cross section and Lambda recoil polarization from the reaction gammad → K0Lambda(p). This work measured these observables over beam energies from 0.90 GeV to 3.0 GeV. These measurements are the first in this channel to cover such a wide range of energies. The data were taken using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Laboratory (JLAB) along with a tagged photon beam. This analysis was completed by identifying events of interest that decayed into the final state topology of pi-pi+pi- p(p). Through conservation of energy and momentum, the K0, Lambda, and missing mass of the spectator proton were reconstructed. Utilizing the same analysis techniques, the observables were measured on two different experiments with good agreement. Photoproduction of strange mesons from the neutron are difficult to measure, consequently there are only a few measurements of this kind. Despite that, these reactions supply essential complementary data to those on the proton. The differential cross sections and the recoil polarization extracted, span the region where new nucleon resonances have been found from studies of the reaction gammap → K +Lambda. Comparisons between the K+Lambda and K0Lambda cross section demonstrate that possible interference terms near 1900 MeV are less pronounced in the latter. This unexpected result inspired a partial wave analyses (PWA) to be fitted to the data. The fit solution shows that this measurement fostered an improvement on the knowledge of observed resonance parameters, necessary to understanding these excited states. The study of nucleon resonances is a key motivating factor since the resonance masses can be calculated from the theory of the strong nuclear force, called quantum chromodynamics, or QCD.

  7. High-frequency wave normals in the solar wind

    SciTech Connect

    Herbert, F.; Smith, L.D.; Sonett, C.P.

    1984-05-01

    High-frequency (0.01--0.04 Hz) magnetic fluctuations in 506 ten-minute intervals of contemporaneous Explorer 35 and Apollo 12 measurements made in the solar wind near the morning side of the Earth's bow shock show the presence of a large population of disturbances resembling Alfven waves. Each wavefront normal n is systematically aligned (median deviation = 35/sup 0/) with , the associated ten-minute average of the magnetic field. Because of variability in the direction of from one interval to another, the coupled distribution of n is nearly isotropic in solar ecliptic coordinates, in contrast with the results of other studies of waves at much lower frequency indicating outward propagation from the sun. Presumably the high frequency waves discussed here are stirred into isotropy (in solar ecliptic coordinates) by following the low frequency fluctuations. As these waves maintain their alignement of n with despite the great variation of , a strong physical alignment constraint is inferred.

  8. A high-frequency electrospray driven by gas volume charges

    SciTech Connect

    Lastochkin, Dmitri; Chang, H.-C.

    2005-06-15

    High-frequency (>10 kHz) ac electrospray is shown to eject volatile dielectric liquid drops by an entirely different mechanism from dc sprays. The steady dc Taylor conic tip is absent and continuous spraying of submicron drops is replaced by individual dynamic pinchoff events involving the entire drop. We attribute this spraying mechanism to a normal Maxwell force produced by an undispersed plasma cloud in front of the meniscus that produces a visible glow at the spherical tip. The volume charge within the cloud is formed by electron-induced gas ionization of the evaporated liquid and produces a large normal field that is much higher than the nominal applied field such that drop ejection occurs at a voltage (at high frequencies) that is as much as ten times lower than that for dc sprays. The ejection force is sensitive to the liquid properties (but not its electrolyte composition), the ac frequency and trace amounts of inert gases, which are believed to catalyze the ionization reactions. As electroneutral drops are ejected, due to the large (>100) ratio between individual drop ejection time and the ac frequency, this mechanism can produce large (microns) electroneutral drops at relatively low voltages.

  9. High-Frequency Normal Mode Propagation in Aluminum Cylinders

    USGS Publications Warehouse

    Lee, Myung W.; Waite, William F.

    2009-01-01

    Acoustic measurements made using compressional-wave (P-wave) and shear-wave (S-wave) transducers in aluminum cylinders reveal waveform features with high amplitudes and with velocities that depend on the feature's dominant frequency. In a given waveform, high-frequency features generally arrive earlier than low-frequency features, typical for normal mode propagation. To analyze these waveforms, the elastic equation is solved in a cylindrical coordinate system for the high-frequency case in which the acoustic wavelength is small compared to the cylinder geometry, and the surrounding medium is air. Dispersive P- and S-wave normal mode propagations are predicted to exist, but owing to complex interference patterns inside a cylinder, the phase and group velocities are not smooth functions of frequency. To assess the normal mode group velocities and relative amplitudes, approximate dispersion relations are derived using Bessel functions. The utility of the normal mode theory and approximations from a theoretical and experimental standpoint are demonstrated by showing how the sequence of P- and S-wave normal mode arrivals can vary between samples of different size, and how fundamental normal modes can be mistaken for the faster, but significantly smaller amplitude, P- and S-body waves from which P- and S-wave speeds are calculated.

  10. Mechanism of high frequency signaling at a depressing ribbon synapse

    PubMed Central

    Grabner, Chad P.; Ratliff, Charles P.; Light, Adam C.; DeVries, Steven H.

    2016-01-01

    SUMMARY Ribbon synapses mediate continuous release in neurons that have graded voltage responses. While mammalian retinas can signal visual flicker at 80-100 Hz, the time constant, τ, for refilling of a depleted vesicle release pool at cone photoreceptor ribbons is 0.7–1.1 s. Due to this prolonged depression, the mechanism for encoding high temporal frequencies is unclear. To determine the mechanism of high frequency signaling, we focused on an Off cone bipolar cell type in the ground squirrel, the cb2, whose transient postsynaptic responses recovered following presynaptic depletion with a τ of ~0.1 s, or 7-10-fold faster than the τ for presynaptic pool refilling. The difference in recovery time course is caused by AMPA receptor saturation, where partial refilling of the presynaptic pool is sufficient for a full postsynaptic response. By limiting the dynamic range of the synapse, receptor saturation counteracts ribbon depression to produce rapid recovery and facilitate high frequency signaling. PMID:27292536

  11. High Frequency PIN-Diode Switches for Radiometer Applications

    NASA Technical Reports Server (NTRS)

    Montes, Oliver; Dawson, Douglas E.; Kangaslahti, Pekka; Reising, Steven C.

    2011-01-01

    Internally calibrated radiometers are needed for ocean topography and other missions. Typically internal calibration is achieved with Dicke switching as one of the techniques. We have developed high frequency single-pole double-throw (SPDT) switches in the form of monolithic microwave integrated circuits (MMIC) that can be easily integrated into Dicke switched radiometers that utilize microstrip technology. In particular, the switches we developed can be used for a radiometer such as the one proposed for the Surface Water and Ocean Topography (SWOT) Satellite Mission whose three channels at 92, 130, and 166 GHz would allow for wet-tropospheric path delay correction near coastal zones and over land. This feat is not possible with the current Jason-class radiometers due to their lower frequency signal measurement and thus lower resolution. The MMIC chips were fabricated at NGST using their InP PIN diode process and measured at JPL using high frequency test equipment. Measurement and simulation results will be presented.

  12. High-frequency dynamics of ultrasound contrast agents.

    PubMed

    Sun, Yang; Kruse, Dustin E; Dayton, Paul A; Ferrara, Katherine W

    2005-11-01

    Ultrasound contrast agents enhance echoes from the microvasculature and enable the visualization of flow in smaller vessels. Here, we optically and acoustically investigate microbubble oscillation and echoes following insonation with a 10 MHz center frequency pulse. A high-speed camera system with a temporal resolution of 10 ns, which provides two-dimensional (2-D) frame images and streak images, is used in optical experiments. Two confocally aligned transducers, transmitting at 10 MHz and receiving at 5 MHz, are used in acoustical experiments in order to detect subharmonic components. Results of a numerical evaluation of the modified Rayleigh-Plesset equation are used to predict the dynamics of a microbubble and are compared to results of in vitro experiments. From the optical observations of a single microbubble, nonlinear oscillation, destruction, and radiation force are observed. The maximum bubble expansion, resulting from insonation with a 20-cycle, 10-MHz linear chirp with a peak negative pressure of 3.5 MPa, has been evaluated. For an initial diameter ranging from 1.5 to 5 microm, a maximum diameter less than 8 microm is produced during insonation. Optical and acoustical experiments provide insight into the mechanisms of destruction, including fragmentation and active diffusion. High-frequency pulse transmission may provide the opportunity to detect contrast echoes resulting from a single pulse, may be robust in the presence of tissue motion, and may provide the opportunity to incorporate high-frequency ultrasound into destruction-replenishment techniques.

  13. Planck 2013 results. VI. High Frequency Instrument data processing

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bock, J. J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bowyer, J. W.; Bridges, M.; Bucher, M.; Burigana, C.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chary, R.-R.; Chen, X.; Chiang, H. C.; Chiang, L.-Y.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giardino, G.; Girard, D.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Hanson, D.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Herent, O.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hou, Z.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Laureijs, R. J.; Lawrence, C. R.; Le Jeune, M.; Leonardi, R.; Leroy, C.; Lesgourgues, J.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; MacTavish, C. J.; Maffei, B.; Mandolesi, N.; Maris, M.; Marleau, F.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matthai, F.; Mazzotta, P.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Melot, F.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Mottet, S.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; North, C.; Noviello, F.; Novikov, D.; Novikov, I.; Orieux, F.; Osborne, S.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Racine, B.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rusholme, B.; Sanselme, L.; Santos, D.; Sauvé, A.; Savini, G.; Scott, D.; Shellard, E. P. S.; Spencer, L. D.; Starck, J.-L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Techene, S.; Terenzi, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vibert, L.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; White, S. D. M.; Yvon, D.; Zacchei, A.; Zonca, A.

    2014-11-01

    Wedescribe the processing of the 531 billion raw data samples from the High Frequency Instrument (HFI), which we performed to produce six temperature maps from the first 473 days of Planck-HFI survey data. These maps provide an accurate rendition of the sky emission at 100, 143, 217, 353, 545, and 857GHz with an angular resolution ranging from 9.´7 to 4.´6. The detector noise per (effective) beam solid angle is respectively, 10, 6 , 12, and 39 μK in the four lowest HFI frequency channels (100-353GHz) and 13 and 14 kJy sr-1 in the 545 and 857 GHz channels. Relative to the 143 GHz channel, these two high frequency channels are calibrated to within 5% and the 353 GHz channel to the percent level. The 100 and 217 GHz channels, which together with the 143 GHz channel determine the high-multipole part of the CMB power spectrum (50 <ℓ < 2500), are calibrated relative to 143 GHz to better than 0.2%.

  14. Optoacoustics for high-frequency ultrasonic imaging and manipulation

    NASA Astrophysics Data System (ADS)

    O'Donnell, Matthew; Buma, Takashi

    2004-05-01

    Pulsed lasers can generate ultrasound through thermoelastic expansion of a thin optical absorber. By carefully designing the optical absorbing structure, efficient transduction is possible for a number of biomedical applications including high-frequency imaging, microfluidics, and sensing. The major key for efficient optoacoustic transduction in biomedical applications is to engineer a nearly perfect optical absorber possessing a large coefficient of thermal expansion with acoustic properties well matched to a water medium. We have obtained an optoacoustic efficiency increase of over 20 dB compared to conventional approaches using a thin, optically absorbing layer consisting of polydimethylsiloxane (PDMS) and carbon black spin coated onto a clear PDMS substrate. This structure has been extensively analyzed both experimentally and analytically and seems to provide opportunities for a wide range of optoacoustic devices. In this talk we show how PDMS-based optoacoustic transduction can be used for high-frequency imaging using longitudinal waves and acoustic tweezing using Lamb waves. The basic mechanism of optoacoustic transduction will be described, and specific devices will be presented.

  15. Carbon nanotube transistor based high-frequency electronics

    NASA Astrophysics Data System (ADS)

    Schroter, Michael

    At the nanoscale carbon nanotubes (CNTs) have higher carrier mobility and carrier velocity than most incumbent semiconductors. Thus CNT based field-effect transistors (FETs) are being considered as strong candidates for replacing existing MOSFETs in digital applications. In addition, the predicted high intrinsic transit frequency and the more recent finding of ways to achieve highly linear transfer characteristics have inspired investigations on analog high-frequency (HF) applications. High linearity is extremely valuable for an energy efficient usage of the frequency spectrum, particularly in mobile communications. Compared to digital applications, the much more relaxed constraints for CNT placement and lithography combined with already achieved operating frequencies of at least 10 GHz for fabricated devices make an early entry in the low GHz HF market more feasible than in large-scale digital circuits. Such a market entry would be extremely beneficial for funding the development of production CNTFET based process technology. This talk will provide an overview on the present status and feasibility of HF CNTFET technology will be given from an engineering point of view, including device modeling, experimental results, and existing roadblocks. Carbon nanotube transistor based high-frequency electronics.

  16. [High-frequency transistor tract for UHF therapy device].

    PubMed

    Tamarchak, D Ia

    1998-01-01

    The paper deals with the specific features of construction of a common circuit and individual units of high-frequency transistor tracts for physiotherapeutic UHF apparatuses whose design is a possible way of conversion of radioelectron equipment. The design of UHF tracts gives rise to some radio engineering problems due to the low output resistance of bipolar transistors and to the operational characteristics of physiotherapeutic equipment and, as a result, the load of the tract is a two-conductor long line loaded with complex resistance whose active part changes slightly and the reactive one varies very greatly. The structure of a high-frequency, which transfers power from the generator with external excitement to the active part of complex load by changing its reactive part in the wide range, was analyzed. It is shown that for reliable operation of the UHF apparatus, its tract should have a multichannel structure with subsequent summation of the power and automatic compensation of the reactive component of alternating load. This provides a measuring mode for the power connected to the patient. The tract structure in question may serve the basis for the designing transistor physiotherapy apparatuses of average and high power (Poutput = 50-400 W).

  17. Phase velocity limit of high-frequency photon density waves

    NASA Astrophysics Data System (ADS)

    Haskell, Richard C.; Svaasand, Lars O.; Madsen, Sten; Rojas, Fabio E.; Feng, T.-C.; Tromberg, Bruce J.

    1995-05-01

    In frequency-domain photon migration (FDPM), two factors make high modulation frequencies desirable. First, with frequencies as high as a few GHz, the phase lag versus frequency plot has sufficient curvature to yield both the scattering and absorption coefficients of the tissue under examination. Second, because of increased attenuation, high frequency photon density waves probe smaller volumes, an asset in small volume in vivo or in vitro studies. This trend toward higher modulation frequencies has led us to re-examine the derivation of the standard diffusion equation (SDE) from the Boltzman transport equation. We find that a second-order time-derivative term, ordinarily neglected in the derivation, can be significant above 1 GHz for some biological tissue. The revised diffusion equation, including the second-order time-derivative, is often termed the P1 equation. We compare the dispersion relation of the P1 equation with that of the SDE. The P1 phase velocity is slower than that predicted by the SDE; in fact, the SDE phase velocity is unbounded with increasing modulation frequency, while the P1 phase velocity approaches c/sqrt(3) is attained only at modulation frequencies with periods shorter than the mean time between scatterings of a photon, a frequency regime that probes the medium beyond the applicability of diffusion theory. Finally we caution that values for optical properties deduced from FDPM data at high frequencies using the SDE can be in error by 30% or more.

  18. Advances in high frequency ultrasound separation of particulates from biomass.

    PubMed

    Juliano, Pablo; Augustin, Mary Ann; Xu, Xin-Qing; Mawson, Raymond; Knoerzer, Kai

    2017-03-01

    In recent years the use of high frequency ultrasound standing waves (megasonics) for droplet or cell separation from biomass has emerged beyond the microfluidics scale into the litre to industrial scale applications. The principle for this separation technology relies on the differential positioning of individual droplets or particles across an ultrasonic standing wave field within the reactor and subsequent biomass material predisposition for separation via rapid droplet agglomeration or coalescence into larger entities. Large scale transducers have been characterised with sonochemiluminescence and hydrophones to enable better reactor designs. High frequency enhanced separation technology has been demonstrated at industrial scale for oil recovery in the palm oil industry and at litre scale to assist olive oil, coconut oil and milk fat separation. Other applications include algal cell dewatering and milk fat globule fractionation. Frequency selection depends on the material properties and structure in the biomass mixture. Higher frequencies (1 and 2MHz) have proven preferable for better separation of materials with smaller sized droplets such as milk fat globules. For palm oil and olive oil, separation has been demonstrated within the 400-600kHz region, which has high radical production, without detectable impact on product quality. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

  19. High-frequency BiCMOS transconductance integrators

    NASA Astrophysics Data System (ADS)

    Beards, R. Douglas

    1990-10-01

    The capabilities of a fine-line bipolar complementary metal oxide semiconductor (BiCMOS) process in the design of wideband transconductance integrators for precision monolithic continuous time filtering are explored. The design considerations of such an integrator are examined in detail, with an emphasis on tunability and phase compensation as a means for realizing a precision wideband design. The concept of open-loop transconductance filtering is described and possible circuit topologies are investigated. Detailed small-signal and large-signal analysis of one proposed circuit which has both tunable bandwidth and tunable phase compensation is presented. Application of such an integrator to open-loop transconductance filtering in the 10-50 MHz frequency range is studied. Simulation results show specific performance expectations of the proposed circuit. The tunable compensation circuit was seen to restrict the amplitude of signals which the integrator can pass without severe distortion or even instability occurring. A potential solution to this problem is deemed to be unsuitable for high frequency applications. The general design philosophy of applying low-frequency techniques to realize a high frequency circuit was seen to result in several fundamental problems.

  20. Advantages of polymer transducers in high frequency inspections

    SciTech Connect

    Samari, S.; Stanton, M.

    1993-12-31

    Since the discovery of piezoelectricity in PVDF in 1969 the polymer transducers have now emerged as a significant tool in many ultrasonic inspections that otherwise would have been very difficult or impossible for conventional ceramic transducers. The major advantage, of Polymer transducers is in their inherent broadband characteristics in immersion applications which leads to their superior resolution and improved signal to noise ration over conventional ceramic transducers. This paper will show empirical results of high frequency polymer transducer in inspection of different materials including engineering materials such as ceramics. Other advantages of the polymer transducers are their low acoustic impedance as well as the compliance of the plastic material during construction. The compliance of the plastic PVDF film allows the manufacture of the high frequency polymer transducers without the use of permanent delays which can interfere with ultrasonic measurements. This paper will also give experimental results that will show how polymer transducers are instrument dependent, and how an operator can achieve optimum results by using an impedance matching network between the instrument and the polymer transducer.

  1. Determination of gas-trapping during high frequency oscillatory ventilation.

    PubMed

    Alexander, J; Milner, A D

    1997-03-01

    To determine the effect of frequency and percent inspiratory time on tidal volume and gas-trapping during high-frequency oscillatory ventilation (HFOV). Nine preterm infants with respiratory distress syndrome tested in the first 48 h of life. Tidal volumes and the presence of gas-trapping were measured by respiratory jacket plethysmography at frequencies of 10, 14, and 17.8 Hz and at inspiratory times of 30%, 50% and 70%, using a commercially available high frequency oscillator.74 Mean (SD) tidal volumes were 2.40 (1.06) ml/kg at 10 Hz, 2.52 (1.07) ml/kg at 14 Hz and fell significantly to 1.96 (0.92) at 17.8 Hz (p < 0.05). Tidal volumes at 50% inspiratory time were significantly greater than at 30% inspiratory time [2.81 (1.42) ml/kg and 2.32 (1.18) ml/kg, respectively] but fell to baseline levels at 70% inspiratory time. There was no significant gas-trapping with increases in either frequency or percent inspiratory time. Gas-trapping is not a significant problem during HFOV in premature infants. Changes in tidal volume with increases in frequency and percent inspiratory time are similar to that seen in animal models.

  2. High-frequency ultrasound imaging for breast cancer biopsy guidance

    PubMed Central

    Cummins, Thomas; Yoon, Changhan; Choi, Hojong; Eliahoo, Payam; Kim, Hyung Ham; Yamashita, Mary W.; Hovanessian-Larsen, Linda J.; Lang, Julie E.; Sener, Stephen F.; Vallone, John; Martin, Sue E.; Kirk Shung, K.

    2015-01-01

    Abstract. Image-guided core needle biopsy is the current gold standard for breast cancer diagnosis. Microcalcifications, an important radiographic finding on mammography suggestive of early breast cancer such as ductal carcinoma in situ, are usually biopsied under stereotactic guidance. This procedure, however, is uncomfortable for patients and requires the use of ionizing radiation. It would be preferable to biopsy microcalcifications under ultrasound guidance since it is a faster procedure, more comfortable for the patient, and requires no radiation. However, microcalcifications cannot reliably be detected with the current standard ultrasound imaging systems. This study is motivated by the clinical need for real-time high-resolution ultrasound imaging of microcalcifications, so that biopsies can be accurately performed under ultrasound guidance. We have investigated how high-frequency ultrasound imaging can enable visualization of microstructures in ex vivo breast tissue biopsy samples. We generated B-mode images of breast tissue and applied the Nakagami filtering technique to help refine image output so that microcalcifications could be better assessed during ultrasound-guided core biopsies. We describe the preliminary clinical results of high-frequency ultrasound imaging of ex vivo breast biopsy tissue with microcalcifications and without Nakagami filtering and the correlation of these images with the pathology examination by hematoxylin and eosin stain and whole slide digital scanning. PMID:26693167

  3. Saltating Snow Mechanics: High Frequency Particle Response to Mountain Wind

    NASA Astrophysics Data System (ADS)

    Aksamit, N. O.; Pomeroy, J. W.

    2015-12-01

    Blowing snow transport theory is currently limited by its dependency on the coupling of time-averaged measurements of particle saltation and suspension and wind speed. Details of the stochastic process of particle transport and complex bed interactions in the saltation layer, along with the influence of boundary-layer turbulence are unobservable with classic measurement techniques. In contrast, recent advances in two-phase sand transport understanding have been spurred by development of high-frequency wind and particle velocity measurement techniques. To advance the understanding of blowing snow, laser illuminated high-speed videography and ultrasonic anemometry were deployed in a mountain environment to examine saltation of snow over a natural snowpack in detail. A saltating snow measurement site was established at the Fortress Mountain Snow Laboratory, Alberta, Canada and instrumented with two Campbell CSAT3 ultrasonic anemometers, four Campbell SR50 ultrasonic snow depth sounders and a two dimensional Particle Tracking Velocimetry (PTV) system. Measurements were collected during nighttime blowing snow events, quantifying snow particle response to high frequency wind gusts. This novel approach permits PTV to step beyond mean statistics of snow transport by identifying sub-species of saltation motion in the first 20 mm above the surface, as well as previously overlooked initiation processes, such as tumbling aggregate snow crystals ejecting smaller grains, then eventually disintegrating and bouncing into entrainment. Spectral characteristics of snow particle ejection and saltation dynamics were also investigated. These unique observations are starting to inform novel conceptualizations of saltating snow transport mechanisms.

  4. Osteogenic Effect of High-frequency Acceleration on Alveolar Bone

    PubMed Central

    Alikhani, M.; Khoo, E.; Alyami, B.; Raptis, M.; Salgueiro, J.M.; Oliveira, S.M.; Boskey, A.; Teixeira, C.C.

    2012-01-01

    Mechanical stimulation contributes to the health of alveolar bone, but no therapy using the osteogenic effects of these stimuli to increase alveolar bone formation has been developed. We propose that the application of high-frequency acceleration to teeth in the absence of significant loading is osteogenic. Sprague-Dawley rats were divided among control, sham, and experimental groups. The experimental group underwent localized accelerations at different frequencies for 5 min/day on the occlusal surface of the maxillary right first molar at a very low magnitude of loading (4 µε). Sham rats received a similar load in the absence of acceleration or frequency. The alveolar bone of the maxilla was evaluated by microcomputed tomography (µCT), histology, fluorescence microscopy, scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR imaging), and RT-PCR for osteogenic genes. Results demonstrate that application of high-frequency acceleration significantly increased alveolar bone formation. These effects were not restricted to the area of application, and loading could be replaced by frequency and acceleration. These studies propose a simple mechanical therapy that may play a significant role in alveolar bone formation and maintenance. PMID:22337699

  5. Neuropathy in female dental personnel exposed to high frequency vibrations.

    PubMed Central

    Akesson, I; Lundborg, G; Horstmann, V; Skerfving, S

    1995-01-01

    OBJECTIVE--To evaluate early neuropathy in dental personnel exposed to high frequency vibrations. METHODS--30 dentists and 30 dental hygienists who used low and high speed hand pieces and ultrasonic scalers were studied, and 30 dental assistants and 30 medical nurses not exposed to vibration (all women). Vibrotactile sensibility, strength, motor performance, sensorineural symptoms and signs, and vascular symptoms in the hands, as well as mercury concentrations in biological samples and cervicobrachial symptoms, were studied. RESULTS--The two groups exposed to vibration had significant impairments of vibrotactile sensibility, strength, and motor performance, as well as more frequent sensorineural symptoms. In the dentists there were significant associations between the vibrotactile sensibility and strength, motor performance, superficial sensibility, and sensorineural symptoms. There were no associations between these findings and cervicobrachial symptoms, mercury concentrations, or smoking. There was no increase of vascular symptoms of the hands in the groups exposed to vibration. CONCLUSION--Dental hygienists and dentists had a slight neuropathy, which may be associated with their exposure to high frequency vibrations, and which may be detrimental to their work performance. Thus, development of safer equipment is urgent. PMID:7757164

  6. 10 K high frequency pulse tube cryocooler with precooling

    NASA Astrophysics Data System (ADS)

    Liu, Sixue; Chen, Liubiao; Wu, Xianlin; Zhou, Yuan; Wang, Junjie

    2016-07-01

    A high frequency pulse tube cryocooler with precooling (HPTCP) has been developed and tested to meet the requirement of weak magnetic signals measurement, and the performance characteristics are presented in this article. The HPTCP is a two-stage pulse tube cryocooler with the precooling-stage replaced by liquid nitrogen. Two regenerators completely filled with stainless steel (SS) meshes are used in the cooler. Together with cold inertance tubes and cold gas reservoir, a cold double-inlet configuration is used to control the phase relationship of the HPTCP. The experimental result shows that the cold double-inlet configuration has improved the performance of the cooler obviously. The effects of operation parameters on the performance of the cooler are also studied. With a precooling temperature of 78.5 K, the maximum refrigeration capacity is 0.26 W at 15 K and 0.92 W at 20 K when the input electric power are 174 W and 248 W respectively, and the minimum no-load temperature obtained is 10.3 K, which is a new record on refrigeration temperature for high frequency pulse tube cryocooler reported with SS completely used as regenerative matrix.

  7. High-frequency Pulse-tube Refrigerator for 4 K

    NASA Astrophysics Data System (ADS)

    Tanaeva, I. A.; Klaasse Bos, C. G.; de Waele, A. T. A. M.

    2006-04-01

    At present pulse-tube refrigerators (PTRs), used for the important temperature region of 4 K, are of the Gifford-McMahon (GM)-type. The main sources of losses in GM-type PTRs are the compressor and the rotary valve. The efficiency of the combination of the compressor and the rotary valve is only about 30%. In addition to that GM-type compressors are heavy and need periodic maintenance. The main goal of this research is to develop a Stirling-type 4-K pulse-tube refrigerator. This implies higher operating frequencies, compared to the usual 1-2 Hz. At higher frequencies a number of properties of a pulse-tube system, such as length-to-diameter ratios of the pulse tubes and the regenerator, volume and configuration of a regenerator material, phase-shift control method, etc., change significantly, and, therefore, require detailed study. The interactions between various parameters of the pulse tube and of the linear compressor are very complicated. Therefore, as a first part of this research, we study the pulse tube at high frequencies, independent of the compressor. We generate high-frequency pressure oscillations, using a GM-type compressor and a special type of rotary valve, which enables us to operate at frequencies up to 20 Hz. Results of this work are described in this contribution.

  8. Phone positioning influence in high-frequency audiometry.

    PubMed

    Crepaldi de Almeida, Elizabeth Oliveira; Nishimori, Aparecida Yumi

    2006-01-01

    Research considers high frequency tonal audiometry as a tool for the early diagnosis of auditory alterations derived from etiological agents. to investigate possible differences in high frequency audiometry of individuals with normal hearing, based on the person who places the earphone. clinical and experimental study with 55 undergraduate students from a country side branch of the São Paulo State University, with normal hearing, underwent two tests each; for the first, the evaluator positioned the earphone on the participant; for the second one, the participant did it by him/herself. An AC40 audiometer calibrated to emit pure tone was used in the frequencies of 10, 12.5, and 16 kHz. The kappa(k) coefficient statistical analysis was used to verify the agreement between the two ways of earphone positioning of earphone, bearing a [FORMULA: SEE TEXT]0.70 kappa value as a criterion. Results attained for both ears were below this criterion, with k average of 0.50. results indicate a risk of compromising the exam reliability when the patient him/herself adjusts phone to his/her own ear. when performing audiometric assessment, this variable must be considered in order to attain reliable results.

  9. Corrosion monitoring using high-frequency guided ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Fromme, Paul

    2014-02-01

    Corrosion develops due to adverse environmental conditions during the life cycle of a range of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Both pitting corrosion and generalized corrosion leading to wall thickness loss can cause the degradation of the structural integrity. The nondestructive detection and monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic transducers with single sided access to the structure, guided wave modes were generated that penetrate through the complete thickness of the structure. The wave propagation and interference of the different guided wave modes depends on the thickness of the structure. Laboratory experiments were conducted and the wall thickness reduced by consecutive milling of the steel structure. Further measurements were conducted using accelerated corrosion in a salt water bath and the damage severity monitored. From the measured signal change due to the wave mode interference the wall thickness reduction was monitored. The high frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

  10. High-frequency filtering of strong-motion records

    USGS Publications Warehouse

    Douglas, J.; Boore, D.M.

    2011-01-01

    The influence of noise in strong-motion records is most problematic at low and high frequencies where the signal to noise ratio is commonly low compared to that in the mid-spectrum. The impact of low-frequency noise (5 Hz) on computed pseudo-absolute response spectral accelerations (PSAs). In contrast to the case of low-frequency noise our analysis shows that filtering to remove high-frequency noise is only necessary in certain situations and that PSAs can often be used up to 100 Hz even if much lower high-cut corner frequencies are required to remove the noise. This apparent contradiction can be explained by the fact that PSAs are often controlled by ground accelerations associated with much lower frequencies than the natural frequency of the oscillator because path and site attenuation (often modelled by Q and κ, respectively) have removed the highest frequencies. We demonstrate that if high-cut filters are to be used, then their corner frequencies should be selected on an individual basis, as has been done in a few recent studies.

  11. High Frequency PIN-Diode Switches for Radiometer Applications

    NASA Technical Reports Server (NTRS)

    Montes, Oliver; Dawson, Douglas E.; Kangaslahti, Pekka; Reising, Steven C.

    2011-01-01

    Internally calibrated radiometers are needed for ocean topography and other missions. Typically internal calibration is achieved with Dicke switching as one of the techniques. We have developed high frequency single-pole double-throw (SPDT) switches in the form of monolithic microwave integrated circuits (MMIC) that can be easily integrated into Dicke switched radiometers that utilize microstrip technology. In particular, the switches we developed can be used for a radiometer such as the one proposed for the Surface Water and Ocean Topography (SWOT) Satellite Mission whose three channels at 92, 130, and 166 GHz would allow for wet-tropospheric path delay correction near coastal zones and over land. This feat is not possible with the current Jason-class radiometers due to their lower frequency signal measurement and thus lower resolution. The MMIC chips were fabricated at NGST using their InP PIN diode process and measured at JPL using high frequency test equipment. Measurement and simulation results will be presented.

  12. A perspective on high-frequency ultrasound for medical applications

    NASA Astrophysics Data System (ADS)

    Mamou, Jonathan; Aristizába, Orlando; Silverman, Ronald H.; Ketterling, Jeffrey A.

    2010-01-01

    High-frequency ultrasound (HFU, >15 MHz) is a rapidly developing field. HFU is currently used and investigated for ophthalmologic, dermatologic, intravascular, and small-animal imaging. HFU offers a non-invasive means to investigate tissue at the microscopic level with resolutions often better than 100 μm. However, fine resolution is only obtained over the limited depth-of-field (˜1 mm) of single-element spherically-focused transducers typically used for HFU applications. Another limitation is penetration depth because most biological tissues have large attenuation at high frequencies. In this study, two 5-element annular arrays with center frequencies of 17 and 34 MHz were fabricated and methods were developed to obtain images with increased penetration depth and depth-of-field. These methods were used in ophthalmologic and small-animal imaging studies. Improved blood sensitivity was obtained when a phantom mimicking a vitreous hemorrhage was imaged. Central-nervous systems of 12.5-day-old mouse embryos were imaged in utero and in three dimensions for the first time.

  13. High-Frequency Dynamics of Ultrasound Contrast Agents

    PubMed Central

    Sun, Yang; Kruse, Dustin E.; Dayton, Paul A.; Ferrara, Katherine W.

    2006-01-01

    Ultrasound contrast agents enhance echoes from the microvasculature and enable the visualization of flow in smaller vessels. Here, we optically and acoustically investigate microbubble oscillation and echoes following insonation with a 10 MHz center frequency pulse. A high-speed camera system with a temporal resolution of 10 ns, which provides two-dimensional (2-D) frame images and streak images, is used in optical experiments. Two confocally aligned transducers, transmitting at 10 MHz and receiving at 5 MHz, are used in acoustical experiments in order to detect subharmonic components. Results of a numerical evaluation of the modified Rayleigh-Plesset equation are used to predict the dynamics of a microbubble and are compared to results of in vitro experiments. From the optical observations of a single microbubble, nonlinear oscillation, destruction, and radiation force are observed. The maximum bubble expansion, resulting from insonation with a 20-cycle, 10-MHz linear chirp with a peak negative pressure of 3.5 MPa, has been evaluated. For an initial diameter ranging from 1.5 to 5 μm, a maximum diameter less than 8 μm is produced during insonation. Optical and acoustical experiments provide insight into the mechanisms of destruction, including fragmentation and active diffusion. High-frequency pulse transmission may provide the opportunity to detect contrast echoes resulting from a single pulse, may be robust in the presence of tissue motion, and may provide the opportunity to incorporate high-frequency ultrasound into destruction-replenishment techniques. PMID:16422410

  14. Corrosion monitoring using high-frequency guided waves

    NASA Astrophysics Data System (ADS)

    Fromme, P.

    2016-04-01

    Corrosion can develop due to adverse environmental conditions during the life cycle of a range of industrial structures, e.g., offshore oil platforms, ships, and desalination plants. Generalized corrosion leading to wall thickness loss can cause the reduction of the strength and thus degradation of the structural integrity. The monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided waves propagating along the structure from accessible areas. Using standard ultrasonic wedge transducers with single sided access to the structure, guided wave modes were selectively generated that penetrate through the complete thickness of the structure. The wave propagation and interference of the different guided wave modes depends on the thickness of the structure. Laboratory experiments were conducted for wall thickness reduction due to milling of the steel structure. From the measured signal changes due to the wave mode interference the reduced wall thickness was monitored. Good agreement with theoretical predictions was achieved. The high frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations from a stand-off distance.

  15. Novel tissue mimicking materials for high frequency breast ultrasound phantoms.

    PubMed

    Cannon, Louise M; Fagan, Andrew J; Browne, Jacinta E

    2011-01-01

    The development and acoustical characterisation of a range of novel agar-based tissue mimicking material (TMMs) for use in clinically relevant, quality assurance (QA) and anthropomorphic breast phantoms are presented. The novel agar-based TMMs described in this study are based on a comprehensive, systematic variation of the ingredients in the International Electrotechnical Commission (IEC) TMM. A novel, solid fat-mimicking material was also developed and acoustically characterised. Acoustical characterisation was carried out using an in-house scanning acoustic macroscope at low (7.5 MHz) and high frequencies (20 MHz), using the pulse-echo insertion technique. The speeds of sound range from 1490 to 1570 m. s(-1), attenuation coefficients range from 0.1 to 0.9 dB. cm(‑1). MHz(-1) and relative backscatter ranges from 0 to -20 dB. It was determined that tissues can be mimicked in terms of independently controllable speeds of sound and attenuation coefficients. These properties make these novel TMMs suitable for use in clinically relevant QA and anthropomorphic phantoms and would potentially be useful for other high frequency applications such as intravascular and small animal imaging. Copyright © 2011 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  16. Very High Frequency (Beyond 100 MHz) PZT Kerfless Linear Arrays

    PubMed Central

    Wu, Da-Wei; Zhou, Qifa; Geng, Xuecang; Liu, Chang-Geng; Djuth, Frank; Shung, K. Kirk

    2010-01-01

    This paper presents the design, fabrication, and measurements of very high frequency kerfless linear arrays prepared from PZT film and PZT bulk material. A 12-µm PZT thick film fabricated from PZT-5H powder/solution composite and a piece of 15-µm PZT-5H sheet were used to fabricate 32-element kerfless high-frequency linear arrays with photolithography. The PZT thick film was prepared by spin-coating of PZT sol-gel composite solution. The thin PZT-5H sheet sample was prepared by lapping a PZT-5H ceramic with a precision lapping machine. The measured results of the 2 arrays were compared. The PZT film array had a center frequency of 120 MHz, a bandwidth of 60% with a parylene matching layer, and an insertion loss of 41 dB. The PZT ceramic sheet array was found to have a center frequency of 128 MHz with a poorer bandwidth (40% with a parylene matching layer) but a better sensitivity (28 dB insertion loss). PMID:19942516

  17. High-frequency oscillations and the neurobiology of schizophrenia

    PubMed Central

    Uhlhaas, Peter J.; Singer, Wolf

    2013-01-01

    Neural oscillations at low- and high-frequency ranges are a fundamental feature of large-scale networks. Recent evidence has indicated that schizophrenia is associated with abnormal amplitude and synchrony of oscillatory activity, in particular, at high (beta/gamma) frequencies. These abnormalities are observed during task-related and spontaneous neuronal activity which may be important for understanding the pathophysiology of the syndrome. In this paper, we shall review the current evidence for impaired beta/gamma-band oscillations and their involvement in cognitive functions and certain symptoms of the disorder. In the first part, we will provide an update on neural oscillations during normal brain functions and discuss underlying mechanisms. This will be followed by a review of studies that have examined high-frequency oscillatory activity in schizophrenia and discuss evidence that relates abnormalities of oscillatory activity to disturbed excitatory/inhibitory (E/I) balance. Finally, we shall identify critical issues for future research in this area. PMID:24174902

  18. Resent developments in high-frequency surface-wave techniques

    NASA Astrophysics Data System (ADS)

    Xia, J.; Pan, Y.; Zeng, C.

    2012-12-01

    High-frequency Rayleigh-wave methods, such as Multi-channel Analysis of Surface Waves (MASW), are getting increasingly attention in the near-surface geophysics and geotechnique community in the last 20 years because of their non-invasive, non-destructive, efficient, and low-cost advantages and their success in environmental and engineering applications. They are viewed by near-surface geophysics community as the one of most promise techniques in the future. However, they face unique problems related to extremely irregular velocity variations in near-surface geology or man-made constructions, for example, highway, foundation, dam, levee, jetty, etc., which are not solvable by techniques or algorithms widely used in earthquake seismology or oil/gas seismic exploration. We present solutions to the problems associated with near-surface materials that possess velocity inverse and high Poisson's ratio. Calculation of dispersion curves by existing algorithms may fail for some special velocity models due to velocity inverse (a high-velocity layer on the top of a low-velocity layer). Two velocity models are most common in near-surface applications. One is a low-velocity half space model and the other a high-velocity topmost layer. The former model results in a complex matrix that no roots can be found in the real number domain, which implies that no phase velocities can be calculated in certain frequency ranges based on current exist algorithms. A solution is to use the real part of the root of the complex number. It is well-known that phase velocities approach about 91% of the shear (S)-wave velocity of the topmost layer when wavelengths are much shorter than the thickness of the topmost layer. The later model, however, results in that phase velocities in a high-frequency range calculated using the current algorithms approach a velocity associated with the S-wave velocity of the second layer NOT the topmost layer. A solution to this problem is to use a two-layer model to

  19. Hearing Risk among Young Personal Listening Device Users: Effects at High-Frequency and Extended High-Frequency Audiogram Thresholds.

    PubMed

    Sulaiman, Ainul Huda; Husain, Ruby; Seluakumaran, Kumar

    2015-08-01

    The usage of personal listening devices (PLDs) is associated with risks of hearing loss. The aim of this study is to evaluate the effects of music exposure from these devices on high-frequency hearing thresholds of PLD users. A total of 282 young adults were questioned regarding their listening habits and symptoms associated with PLD listening. Their audiogram thresholds were determined at high (3-8 kHz) frequencies and extended high frequencies (EHFs, 9-16 kHz). The preferred listening volumes of PLD users were used to compute their overall 8-h equivalent music exposure levels (LAeq8h). Approximately 80% of the subjects were regular PLD users. Of these, 20.1% had LAeq8h of ≥75 dBA, while 4.4% of them had LAeq8h of ≥85 dBA, which carries a high risk of hearing damage. Compared with those exposed to LAeq8h of <75 dBA, subjects who had LAeq8h of ≥75 dBA reported a significantly higher incidence of tinnitus and difficulty in hearing others immediately after using PLDs. PLD users who were exposed to LAeq8h of ≥75 dBA and had been using their devices for ≥4 years also showed significantly higher mean audiogram thresholds compared with non-users at most EHFs tested. In addition, the thresholds of PLD users at EHFs showed a weak but significant positive correlation with their LAeq8h. The present findings suggest that excessive exposure to music among PLD users may lead to initial effects on their hearing at very high frequencies.

  20. Microscale capillary wave turbulence excited by high frequency vibration.

    PubMed

    Blamey, Jeremy; Yeo, Leslie Y; Friend, James R

    2013-03-19

    Low frequency (O(10 Hz-10 kHz)) vibration excitation of capillary waves has been extensively studied for nearly two centuries. Such waves appear at the excitation frequency or at rational multiples of the excitation frequency through nonlinear coupling as a result of the finite displacement of the wave, most often at one-half the excitation frequency in so-called Faraday waves and twice this frequency in superharmonic waves. Less understood, however, are the dynamics of capillary waves driven by high-frequency vibration (>O(100 kHz)) and small interface length scales, an arrangement ideal for a broad variety of applications, from nebulizers for pulmonary drug delivery to complex nanoparticle synthesis. In the few studies conducted to date, a marked departure from the predictions of classical Faraday wave theory has been shown, with the appearance of broadband capillary wave generation from 100 Hz to the excitation frequency and beyond, without a clear explanation. We show that weak wave turbulence is the dominant mechanism in the behavior of the system, as evident from wave height frequency spectra that closely follow the Rayleigh-Jeans spectral response η ≈ ω(-17/12) as a consequence of a period-halving, weakly turbulent cascade that appears within a 1 mm water drop whether driven by thickness-mode or surface acoustic Rayleigh wave excitation. However, such a cascade is one-way, from low to high frequencies. The mechanism of exciting the cascade with high-frequency acoustic waves is an acoustic streaming-driven turbulent jet in the fluid bulk, driving the fundamental capillary wave resonance through the well-known coupling between bulk flow and surface waves. Unlike capillary waves, turbulent acoustic streaming can exhibit subharmonic cascades from high to low frequencies; here it appears from the excitation frequency all the way to the fundamental modes of the capillary wave at some four orders of magnitude in frequency less than the excitation frequency

  1. Inaudible high-frequency sounds affect brain activity: hypersonic effect.

    PubMed

    Oohashi, T; Nishina, E; Honda, M; Yonekura, Y; Fuwamoto, Y; Kawai, N; Maekawa, T; Nakamura, S; Fukuyama, H; Shibasaki, H

    2000-06-01

    Although it is generally accepted that humans cannot perceive sounds in the frequency range above 20 kHz, the question of whether the existence of such "inaudible" high-frequency components may affect the acoustic perception of audible sounds remains unanswered. In this study, we used noninvasive physiological measurements of brain responses to provide evidence that sounds containing high-frequency components (HFCs) above the audible range significantly affect the brain activity of listeners. We used the gamelan music of Bali, which is extremely rich in HFCs with a nonstationary structure, as a natural sound source, dividing it into two components: an audible low-frequency component (LFC) below 22 kHz and an HFC above 22 kHz. Brain electrical activity and regional cerebral blood flow (rCBF) were measured as markers of neuronal activity while subjects were exposed to sounds with various combinations of LFCs and HFCs. None of the subjects recognized the HFC as sound when it was presented alone. Nevertheless, the power spectra of the alpha frequency range of the spontaneous electroencephalogram (alpha-EEG) recorded from the occipital region increased with statistical significance when the subjects were exposed to sound containing both an HFC and an LFC, compared with an otherwise identical sound from which the HFC was removed (i.e., LFC alone). In contrast, compared with the baseline, no enhancement of alpha-EEG was evident when either an HFC or an LFC was presented separately. Positron emission tomography measurements revealed that, when an HFC and an LFC were presented together, the rCBF in the brain stem and the left thalamus increased significantly compared with a sound lacking the HFC above 22 kHz but that was otherwise identical. Simultaneous EEG measurements showed that the power of occipital alpha-EEGs correlated significantly with the rCBF in the left thalamus. Psychological evaluation indicated that the subjects felt the sound containing an HFC to be more

  2. A recoil resilient lumen support, design, fabrication and mechanical evaluation

    NASA Astrophysics Data System (ADS)

    Mehdizadeh, Arash; Ali, Mohamed Sultan Mohamed; Takahata, Kenichi; Al-Sarawi, Said; Abbott, Derek

    2013-06-01

    Stents are artificial implants that provide scaffolding to a cavity inside the body. This paper presents a new luminal device for reducing the mechanical failure of stents due to recoil, which is one of the most important issues in stenting. This device, which we call a recoil-resilient ring (RRR), is utilized standalone or potentially integrated with existing stents to address the problem of recoil. The proposed structure aims to minimize the need for high-pressure overexpansion that can induce intra-luminal trauma and excess growth of vascular tissue causing later restenosis. The RRR is an overlapped open ring with asymmetrical sawtooth structures that are intermeshed. These teeth can slide on top of each other, while the ring is radially expanded, but interlock step-by-step so as to keep the final expanded state against compressional forces that normally cause recoil. The RRRs thus deliver balloon expandability and, when integrated with a stent, bring both radial rigidity and longitudinal flexibility to the stent. The design of the RRR is investigated through finite element analysis (FEA), and then the devices are fabricated using micro-electro-discharge machining of 200-µm-thick Nitinol sheet. The standalone RRR is balloon expandable in vitro by 5-7 Atm in pressure, which is well within the recommended in vivo pressure ranges for stenting procedures. FEA compression tests indicate 13× less reduction of the cross-sectional area of the RRR compared with a typical stainless steel stent. These results also show perfect elastic recovery of the RRR after removal of the pressure compared to the remaining plastic deformations of the stainless steel stent. On the other hand, experimental loading tests show that the fabricated RRRs have 2.8× radial stiffness compared to a two-column section of a commercial stent while exhibiting comparable elastic recovery. Furthermore, testing of in vitro expansion in a mock artery tube shows around 2.9% recoil, approximately 5-11

  3. Tropospheric Emission Spectrometer and Airborne Emission Spectrometer

    NASA Technical Reports Server (NTRS)

    Glavich, T.; Beer, R.

    1996-01-01

    The Tropospheric Emission Spectrometer (TES) is an instrument being developed for the NASA Earth Observing System Chemistry Platform. TES will measure the distribution of ozone and its precursors in the lower atmosphere. The Airborne Emission Spectrometer (AES) is an aircraft precursor to TES. Applicable descriptions are given of instrument design, technology challenges, implementation and operations for both.

  4. Active Control of High-Frequency Combustor Instability Demonstrated

    NASA Technical Reports Server (NTRS)

    DeLaat, John C.; Chang, Clarence T.

    2003-01-01

    To reduce the environmental impact of aerospace propulsion systems, extensive research is being done in the development of lean-burning (low fuel-to-air ratio) combustors that can reduce emissions throughout the mission cycle. However, these lean-burning combustors have an increased susceptibility to thermoacoustic instabilities-high-pressure oscillations much like sound waves that can cause severe high-frequency vibrations in the combustor. These pressure waves can fatigue the combustor components and even the downstream turbine blades. This can significantly decrease the combustor and turbine safe operating life. Thus, suppression of the thermoacoustic combustor instabilities is an enabling technology for lean, low-emissions combustors. Under the Propulsion and Power Program, the NASA Glenn Research Center in partnership with Pratt & Whitney, United Technologies Research Center, and Georgia Institute of Technology is developing technologies for the active control of combustion instabilities.

  5. Development of high frequency and wide bandwidth Johnson noise thermometry

    SciTech Connect

    Crossno, Jesse; Liu, Xiaomeng; Kim, Philip; Ohki, Thomas A.; Fong, Kin Chung

    2015-01-12

    We develop a high frequency, wide bandwidth radiometer operating at room temperature, which augments the traditional technique of Johnson noise thermometry for nanoscale thermal transport studies. Employing low noise amplifiers and an analog multiplier operating at 2 GHz, auto- and cross-correlated Johnson noise measurements are performed in the temperature range of 3 to 300 K, achieving a sensitivity of 5.5 mK (110 ppm) in 1 s of integration time. This setup allows us to measure the thermal conductance of a boron nitride encapsulated monolayer graphene device over a wide temperature range. Our data show a high power law (T ∼ 4) deviation from the Wiedemann-Franz law above T ∼ 100 K.

  6. Toward a High-Frequency Pulsed-Detonation Actuator

    NASA Technical Reports Server (NTRS)

    Cutler, Andrew D.; Drummond, J. Philip

    2006-01-01

    This paper describes the continued development of an actuator, energized by pulsed detonations, that provides a pulsed jet suitable for flow control in high-speed applications. A high-speed valve, capable of delivering a pulsed stream of reactants a mixture of H2 and air at rates of up to 1500 pulses per second, has been constructed. The reactants burn in a resonant tube and the products exit the tube as a pulsed jet. High frequency pressure transducers have been used to monitor the pressure fluctuations in the device at various reactant injection frequencies, including both resonant and off-resonant conditions. Pulsed detonations have been demonstrated in the lambda/4 mode of an 8 inch long tube at approx. 600 Hz. The pulsed jet at the exit of the device has been observed using shadowgraph and an infrared camera.

  7. Toward a High-Frequency Pulsed-Detonation Actuator

    NASA Technical Reports Server (NTRS)

    Cutler, Andrew D.; Drummond, J. Philip

    2006-01-01

    This paper describes the continued development of an actuator, energized by pulsed detonations, that provides a pulsed jet suitable for flow control in high-speed applications. A high-speed valve, capable of delivering a pulsed stream of reactants a mixture of H2 and air at rates of up to 1500 pulses per second, has been constructed. The reactants burn in a resonant tube and the products exit the tube as a pulsed jet. High frequency pressure transducers have been used to monitor the pressure fluctuations in the device at various reactant injection frequencies, including both resonant and off-resonant conditions. Pulsed detonations have been demonstrated in the lambda/4 mode of an 8 inch long tube at approximately 600 Hz. The pulsed jet at the exit of the device has been observed using shadowgraph and an infrared camera.

  8. High-frequency electric field measurement using a toroidal antenna

    DOEpatents

    Lee, Ki Ha

    2002-01-01

    A simple and compact method and apparatus for detecting high frequency electric fields, particularly in the frequency range of 1 MHz to 100 MHz, uses a compact toroidal antenna. For typical geophysical applications the sensor will be used to detect electric fields for a wide range of spectrum starting from about 1 MHz, in particular in the frequency range between 1 to 100 MHz, to detect small objects in the upper few meters of the ground. Time-varying magnetic fields associated with time-varying electric fields induce an emf (voltage) in a toroidal coil. The electric field at the center of (and perpendicular to the plane of) the toroid is shown to be linearly related to this induced voltage. By measuring the voltage across a toroidal coil one can easily and accurately determine the electric field.

  9. Effect of high-frequency modes on singlet fission dynamics

    NASA Astrophysics Data System (ADS)

    Fujihashi, Yuta; Chen, Lipeng; Ishizaki, Akihito; Wang, Junling; Zhao, Yang

    2017-01-01

    Singlet fission is a spin-allowed energy conversion process whereby a singlet excitation splits into two spin-correlated triplet excitations residing on adjacent molecules and has a potential to dramatically increase the efficiency of organic photovoltaics. Recent time-resolved nonlinear spectra of pentacene derivatives have shown the importance of high frequency vibrational modes in efficient fission. In this work, we explore impacts of vibration-induced fluctuations on fission dynamics through quantum dynamics calculations with parameters from fitting measured linear and nonlinear spectra. We demonstrate that fission dynamics strongly depends on the frequency of the intramolecular vibrational mode. Furthermore, we examine the effect of two vibrational modes on fission dynamics. Inclusion of a second vibrational mode creates an additional fission channel even when its Huang-Rhys factor is relatively small. Addition of more vibrational modes may not enhance the fission per se, but can dramatically affect the interplay between fission dynamics and the dominant vibrational mode.

  10. Spectroscopic measurements of high frequency plasma in supercritical carbon dioxide

    SciTech Connect

    Maehara, T.; Mukasa, S.; Takemori, T.; Watanabe, T.; Kurokawa, K.; Toyota, H.; Nomura, S.; Kawashima, A.; Iwamae, A.

    2009-03-15

    Spectroscopic measurements of high frequency (hf) plasma were performed under high pressure conditions (5 and 7 MPa) and supercritical (sc) CO{sub 2} conditions (8-20 MPa). Temperature evaluated from C{sub 2} Swan bands (d {sup 3}{pi}{sub g}{yields}a {sup 3}{pi}{sub u}) increased from 3600 to 4600 K with an increase in pressure. The first observation of broadening and shifting of the O I line profile (3p {sup 5} P{sub 3,2,1}{yields}3s {sup 5} S{sub 2}{sup 0}) of hf plasma under sc CO{sub 2} conditions was carried out. However, the origin of broadening and the shifting cannot be understood because the present theory explaining them is not valid for such high pressure conditions.

  11. High-frequency shear-horizontal surface acoustic wave sensor

    DOEpatents

    Branch, Darren W

    2013-05-07

    A Love wave sensor uses a single-phase unidirectional interdigital transducer (IDT) on a piezoelectric substrate for leaky surface acoustic wave generation. The IDT design minimizes propagation losses, bulk wave interferences, provides a highly linear phase response, and eliminates the need for impedance matching. As an example, a high frequency (.about.300-400 MHz) surface acoustic wave (SAW) transducer enables efficient excitation of shear-horizontal waves on 36.degree. Y-cut lithium tantalate (LTO) giving a highly linear phase response (2.8.degree. P-P). The sensor has the ability to detect at the pg/mm.sup.2 level and can perform multi-analyte detection in real-time. The sensor can be used for rapid autonomous detection of pathogenic microorganisms and bioagents by field deployable platforms.

  12. High-frequency shear-horizontal surface acoustic wave sensor

    DOEpatents

    Branch, Darren W

    2014-03-11

    A Love wave sensor uses a single-phase unidirectional interdigital transducer (IDT) on a piezoelectric substrate for leaky surface acoustic wave generation. The IDT design minimizes propagation losses, bulk wave interferences, provides a highly linear phase response, and eliminates the need for impedance matching. As an example, a high frequency (.about.300-400 MHz) surface acoustic wave (SAW) transducer enables efficient excitation of shear-horizontal waves on 36.degree. Y-cut lithium tantalate (LTO) giving a highly linear phase response (2.8.degree. P-P). The sensor has the ability to detect at the pg/mm.sup.2 level and can perform multi-analyte detection in real-time. The sensor can be used for rapid autonomous detection of pathogenic microorganisms and bioagents by field deployable platforms.

  13. Discrete pulse modulation strategies for high-frequency inverter systems

    SciTech Connect

    Venkataramanan, G. . Dept. of Electrical Engineering); Divan, D.M. . Dept. of Electrical and Computer Engineering); Jahns, T.M. )

    1993-07-01

    High-performance high-frequency inverter systems for UPS applications represent a demanding application that cannot be easily realized using conventional hard-switched PWM inverter topologies. Adoption of typical soft-switched inverters such as the resonant dc link inverter require the use of discrete pulse modulation strategies. New controller structures are necessary to cope with stringent voltage regulation and distortion constraints in the presence of unbalanced and nonlinear loads. This paper presents a controller that utilizes load current feed-forward strategy with a cost function current regulator to achieve excellent transient performance characteristics. Voltage regulation is ensured using a synchronous frame regulator. Detailed simulation and experimental results verifying the concepts are presented. Although this paper focuses on soft-switching inverters, the control concepts can be applied to conventional hard-switching inverters as well.

  14. Status asthmaticus treated by high-frequency oscillatory ventilation.

    PubMed

    Duval, E L; van Vught, A J

    2000-10-01

    We present a 2.5-year-old girl in severe asthma crisis who clinically deteriorated on conventional mechanical ventilation, but was successfully ventilated with high-frequency oscillatory ventilation (HFOV). Although HFOV is accepted as a technique for managing pediatric respiratory failure, its use in obstructive airway disease is generally thought to be contraindicated because of the risk of dynamic air-trapping. However, we suggest that obstructive airway disease can safely be managed with HFOV, provided certain conditions are met. These include the application of sufficiently high mean airway pressures to open and stent the airways ("an open airway strategy"), lower frequencies to overcome the greater attenuation of the oscillatory waves in the narrowed airways, permissive hypercapnia to enable reducing pressure swings as much as possible, longer expiratory times, and muscle paralysis to avoid spontaneous breathing.

  15. Spectral representation of high-frequency Space Shuttle data

    NASA Technical Reports Server (NTRS)

    Spanos, P. D.; Mushung, L. J.; Nelson, D. A., Jr.; Hamilton, D. A.

    1994-01-01

    High frequency Space Shuttle liftoff data are treated by autoregressive (AR) and autoregressive-moving-average (ARMA) digital algorithms. These algorithms provide useful information on the spectral densities of the data. Further, they yield spectral models, which lend themeselves to incorporation into the concept of the random response spectrum. This concept yields a reasonably smooth power spectrum for the design of structural and mechanical systems when the available data bank is limited. Due to the nonstationary of the liftoff event, the pertinent data are split into three slices. Each of the slices is associated with a rather distinguished phase of the liftoff event, in which stationarity can be expected. The presented results are preliminary in nature; they aim to call attention to the availability of the discussed concepts and to the need to augment the Space Shuttle data bank as more flights are completed.

  16. Recording and analysis techniques for high-frequency oscillations.

    PubMed

    Worrell, G A; Jerbi, K; Kobayashi, K; Lina, J M; Zelmann, R; Le Van Quyen, M

    2012-09-01

    In recent years, new recording technologies have advanced such that, at high temporal and spatial resolutions, high-frequency oscillations (HFO) can be recorded in human partial epilepsy. However, because of the deluge of multichannel data generated by these experiments, achieving the full potential of parallel neuronal recordings depends on the development of new data mining techniques to extract meaningful information relating to time, frequency and space. Here, we aim to bridge this gap by focusing on up-to-date recording techniques for measurement of HFO and new analysis tools for their quantitative assessment. In particular, we emphasize how these methods can be applied, what property might be inferred from neuronal signals, and potentially productive future directions.

  17. High-Frequency, High-Temperature Fretting Experiments

    NASA Technical Reports Server (NTRS)

    Matlik, J. F.; Farris, T. N.; Haake, F. K.; Swanson, G. R.; Duke, G. C.

    2005-01-01

    Fretting is a structural damage mechanism observed when two nominally clamped surfaces are subjected to an oscillatory loading. A critical location for fretting induced damage has been identified at the blade/disk and blade/damper interfaces of gas turbine engine turbomachinery and space propulsion components. The high-temperature, high-frequency loading environment seen by these components lead to severe stress gradients at the edge-of-contact. These contact stresses drive crack nucleation and propagation in fretting and are very sensitive to the geometry of the contacting bodies, the contact loads, materials, temperature, and contact surface tribology (friction). To diagnose the threat that small and relatively undetectable fretting cracks pose to damage tolerance and structural integrity of in-service components, the objective of this work is to develop a well-characterized experimental fretting rig capable of investigating fretting behavior of advanced aerospace alloys subjected to load and temperature conditions representative of such turbomachinery components.

  18. Semiconductor materials for high frequency solid state sources

    NASA Astrophysics Data System (ADS)

    Grubin, H. L.

    1983-03-01

    The broad goal of the subject contract is to suggest candidate materials for high frequency device operation. During the initial phase of the study, attention has been focused on defining the general role of the band structure and associated scattering processes in determining the response of semiconductors to transient high-speed electrical signals. Moments of the Boltzmann transport equation form the basis of the study, and the scattering rates define the semiconductor under study. The selection of semiconductor materials proceeds from a set of simple, yet significant, set of scaling principles. During the first quarter scaling was associated with what can formally be identified as velocity invariants, but which in more practical terms identifies the relative speed advantages of e.g., InP over GaAs.

  19. Diffusion coefficient in hydrogel under high-frequency ultrasound

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Akira; Tanaka, Kei; Kumata, Tatsuya; Watanabe, Yoshiaki; Miyata, Shogo; Furukawa, Katsuko; Ushida, Takashi

    2007-03-01

    Modulating hydrogel properties by external stimuli can be applied for drug delivery system. For example, ultrasound can enhance drug release from hydrogel by the mechanism which is not fully understood. We measured diffusion coefficient in hydrogel under high-frequency ultrasound to understand mass transport property. To estimate diffusion coefficient, FRAP (fluorescence recovery after photobleaching) technique was applied with time-lapse fluorescence microscopy and we analyzed fluorescence recovery after photobleaching of FITC-dextran (4˜40 kDa) which was fully fused in agarose gel (1˜3 %). As a result, diffusion coefficient was altered when agarose gel was sonicated by 1MHz ultrasound with 400kPa (peak-peak). We discussed several possible underlying mechanisms such as cavitation, heat and phase transition with extended experimental data.

  20. Effect of high-frequency modes on singlet fission dynamics.

    PubMed

    Fujihashi, Yuta; Chen, Lipeng; Ishizaki, Akihito; Wang, Junling; Zhao, Yang

    2017-01-28

    Singlet fission is a spin-allowed energy conversion process whereby a singlet excitation splits into two spin-correlated triplet excitations residing on adjacent molecules and has a potential to dramatically increase the efficiency of organic photovoltaics. Recent time-resolved nonlinear spectra of pentacene derivatives have shown the importance of high frequency vibrational modes in efficient fission. In this work, we explore impacts of vibration-induced fluctuations on fission dynamics through quantum dynamics calculations with parameters from fitting measured linear and nonlinear spectra. We demonstrate that fission dynamics strongly depends on the frequency of the intramolecular vibrational mode. Furthermore, we examine the effect of two vibrational modes on fission dynamics. Inclusion of a second vibrational mode creates an additional fission channel even when its Huang-Rhys factor is relatively small. Addition of more vibrational modes may not enhance the fission per se, but can dramatically affect the interplay between fission dynamics and the dominant vibrational mode.

  1. High-frequency techniques for RCS prediction of plate geometries

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; Polka, Lesley A.

    1991-01-01

    Several different high-frequency methods for modeling the radar cross sections (RCSs) of plate geometries are examined. The Method of Equivalent Currents and a numerically derived corner diffraction coefficient are used to model the RCS of a rectangular, perfectly conducting plate in nonprincipal planes. The Uniform Theory of Diffraction is used to model the RCS of a rectangular, perfectly conducting plate in principal planes. For the soft polarization case, first-order and slope-diffraction terms are included. For the hard polarization case, up to four orders of diffraction are included. Finally, the Uniform Theory of Diffraction for impedance wedges and the Impedance Boundary Condition are used to model the RCS of a coated, rectangular plate in principal planes. In most of the cases considered, comparisons are made between theoretical and experimental results.

  2. Ultrasonic high frequency lamb waves for evaluation of plate structures

    NASA Astrophysics Data System (ADS)

    Ranjbar Naserabadi, M. J.; Sodagar, S.

    2017-07-01

    The potentials of high frequency Lamb wave modes are investigated in the inspection of plate-like structures. The wave propagation characteristics of higher order wave modes and the corresponding sensitivity and detectability are studied. Finite element simulations are carried out using infinite elements to model the ultrasonic wedge transducer and the inspection system. Experimental pulse-echo measurements are conducted to verify the influence of different modes characteristics predicted from the finite element simulations. The experimental measurements show a good agreement with the obtained numerical results for the fundamental modes, S0 and A0, and the higher order modes, S1 and A1, at 4 MHz mm of frequency-thickness.

  3. Aftershock Prediction for High-Frequency Financial Markets' Dynamics

    NASA Astrophysics Data System (ADS)

    Baldovin, Fulvio; Camana, Francesco; Caraglio, Michele; Stella, Attilio L.; Zamparo, Marco

    The occurrence of aftershocks following a major financial crash manifests the critical dynamical response of financial markets. Aftershocks put additional stress on markets, with conceivable dramatic consequences. Such a phenomenon has been shown to be common to most financial assets, both at high and low frequency. Its present-day description relies on an empirical characterization proposed by Omori at the end of 1800 for seismic earthquakes. We point out the limited predictive power in this phenomenological approach and present a stochastic model, based on the scaling symmetry of financial assets, which is potentially capable to predict aftershocks occurrence, given the main shock magnitude. Comparisons with S&P high-frequency data confirm this predictive potential.

  4. Design and development of mode launcher for high frequency Gyrotron

    NASA Astrophysics Data System (ADS)

    Alaria, Mukesh Kumar; Sinha, A. K.; Khatun, H.

    2016-03-01

    In this paper, we describe the design and development of helical cut smooth wall mode launcher for high frequency and high power Gyrotron. A Vlasov-type helical cut mode launcher for converting TE22,6 mode to a Gaussian mode has been designed for 120 GHz, 1 MW Gyrotron. The initial design of mode launcher has been optimized using LOT/SURF-3D software. The mode launcher diameter and length are optimized considering the minimum return loss and the minimum insertion loss by using CST microwave studio. The return loss (S11) and insertion loss (S21) performance of helical cut smooth wall mode launcher have been obtained using CST-Microwave Studio. The fabrication of Vlasov-type helical cut mode launcher for 120 GHz Gyrotron has also been carried out.

  5. Recording and analysis techniques for high-frequency oscillations

    PubMed Central

    Worrell, G.A.; Jerbi, K.; Kobayashi, K.; Lina, J.M.; Zelmann, R.; Le Van Quyen, M.

    2013-01-01

    In recent years, new recording technologies have advanced such that, at high temporal and spatial resolutions, high-frequency oscillations (HFO) can be recorded in human partial epilepsy. However, because of the deluge of multichannel data generated by these experiments, achieving the full potential of parallel neuronal recordings depends on the development of new data mining techniques to extract meaningful information relating to time, frequency and space. Here, we aim to bridge this gap by focusing on up-to-date recording techniques for measurement of HFO and new analysis tools for their quantitative assessment. In particular, we emphasize how these methods can be applied, what property might be inferred from neuronal signals, and potentially productive future directions. PMID:22420981

  6. Reduced length fibre Bragg gratings for high frequency acoustic sensing

    NASA Astrophysics Data System (ADS)

    Davis, Claire; Robertson, David; Brooks, Chris; Norman, Patrick; Rosalie, Cedric; Rajic, Nik

    2014-12-01

    In-fibre Bragg gratings (FBGs) are now well established for applications in acoustic sensing. The upper frequency response limit of the Bragg grating is determined by its gauge length, which has typically been limited to about 1 mm for commercially available Type 1 gratings. This paper investigates the effect of FBG gauge length on frequency response for sensing of acoustic waves. The investigation shows that the ratio of wavelength to FBG length must be at least 8.8 in order to reliably resolve the strain response without significant gain roll-off. Bragg gratings with a gauge length of 200 µm have been fabricated and their capacity to measure low amplitude high frequency acoustic strain fields in excess of 2 MHz is experimentally demonstrated. The ultimate goal of this work is to enhance the sensitivity of acoustic damage detection techniques by extending the frequency range over which acoustic waves may be reliably measured using FBGs.

  7. High frequency conductivity of hot electrons in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Amekpewu, M.; Mensah, S. Y.; Musah, R.; Mensah, N. G.; Abukari, S. S.; Dompreh, K. A.

    2016-05-01

    High frequency conductivity of hot electrons in undoped single walled achiral Carbon Nanotubes (CNTs) under the influence of ac-dc driven fields was considered. We investigated semi-classically Boltzmann's transport equation with and without the presence of the hot electrons' source by deriving the current densities in CNTs. Plots of the normalized current density versus frequency of ac-field revealed an increase in both the minimum and maximum peaks of normalized current density at lower frequencies as a result of a strong injection of hot electrons. The applied ac-field plays a twofold role of suppressing the space-charge instability in CNTs and simultaneously pumping an energy for lower frequency generation and amplification of THz radiations. These have enormous promising applications in very different areas of science and technology.

  8. Influence of pore roughness on high-frequency permeability

    NASA Astrophysics Data System (ADS)

    Cortis, Andrea; Smeulders, David M. J.; Guermond, Jean Luc; Lafarge, Denis

    2003-06-01

    The high-frequency behavior of the fluid velocity patterns for smooth and corrugated pore channels is studied. The classical approach of Johnson et al. [J. Fluid Mech. 176, 379 (1987)] for smooth geometries is obtained in different manners, thus clarifying differences with Sheng and Zhou [Phys. Rev. Lett. 61, 1591 (1988)] and Avellaneda and Torquato [Phys. Fluids A 3, 2529 (1991)]. For wedge-shaped pore geometries, the classical approach is modified by a nonanalytic extension proposed by Achdou and Avellaneda [Phys. Fluids A 4, 2561 (1992)]. The dependency of the nonanalytic extension on the apex angle of the wedge was derived. Precise numerical computations for various apex angles in two-dimensional channels confirmed this theoretical dependency, which is somewhat different from the original Achdou and Avellaneda predictions. Moreover, it was found that the contribution of the singularities does not alter the parameters of the classical theory by Johnson et al..

  9. Development of high frequency and wide bandwidth Johnson noise thermometry

    NASA Astrophysics Data System (ADS)

    Crossno, Jesse; Liu, Xiaomeng; Ohki, Thomas A.; Kim, Philip; Fong, Kin Chung

    2015-01-01

    We develop a high frequency, wide bandwidth radiometer operating at room temperature, which augments the traditional technique of Johnson noise thermometry for nanoscale thermal transport studies. Employing low noise amplifiers and an analog multiplier operating at 2 GHz, auto- and cross-correlated Johnson noise measurements are performed in the temperature range of 3 to 300 K, achieving a sensitivity of 5.5 mK (110 ppm) in 1 s of integration time. This setup allows us to measure the thermal conductance of a boron nitride encapsulated monolayer graphene device over a wide temperature range. Our data show a high power law (T ˜ 4) deviation from the Wiedemann-Franz law above T ˜ 100 K.

  10. Development oF High Frequency Electromagnetic Mapping (HFEM) technology

    NASA Astrophysics Data System (ADS)

    Jesch, R. L.

    1982-04-01

    High frequency electromagnetic mapping (HFEM) techniques were developed for evaluating rubblized oil shale in the cold retort state in the modified in situ process. This technology development is also applicable for using HFEM techniques for diagnosing, monitoring, controlling and evaluating modified in situ retorts after they are ignited. The baseline data work required to design a high temperature sample holder and experiments for determining the EM properties of oil shale samples at elevated temperatures (200 to 500 C) are described. A theoretical approach is given for modeling oil shale retorts for electromagnetic sensing techniques by a spheroid with an average dielectric constant along with numerical results. Finally, the measurement results are given for the spent and raw shale samples that were obtained from portions of the ten half score samples plus the results of the electromagnetic transmission measurements taken on oil shale samples.

  11. Discrete pulse modulation strategies for high-frequency inverter systems

    NASA Astrophysics Data System (ADS)

    Venkataramanan, Giri; Divan, Deepakraj M.; Jahns, Thomas M.

    1993-07-01

    High-performance, high-frequency inverter systems for UPS (uninterruptible power system) applications cannot be easily realized using conventional hard-switched PWM inverter topologies. Adoption of typical soft-switched inverters such as the resonant dc link inverter require the use of discrete pulse modulation strategies. New controller structures are necessary to cope with stringent voltage regulation and distortion constraints in the presence of unbalanced and nonlinear loads. A controller that utilizes a load current feedforward strategy with a cost function current regulator to achieve excellent transient performance characteristics is presented. Voltage regulation is ensured using a synchronous frame regulator. Detailed simulation and experimental results verifying the concepts are presented. Although this work focuses on soft-switching inverters, the control concepts can be applied to conventional hard-switching inverters as well.

  12. Longitudinal impedance of a periodic structure at high frequency

    NASA Astrophysics Data System (ADS)

    Gluckstern, R. L.

    1989-05-01

    An ultrarelativistic beam bunch traveling along the axis of an azimuthally symmetric cavity of general shape connected to a beam pipe generates wake fields. We extend an earlier derivation of the integral equation for the axial electric field at the beam-pipe radius to the case of a periodic structure. This equation is then solved in the high-frequency limit, and we show that the reciprocal of the impedance per cell has a particularly simple form, closely related to the admittance for a single cavity. We also show that the imaginary part of the impedance per cell varies as ω-1 and the real part of the impedance per cell varies as ω-3/2. Finally, the results are shown to satisfy the requirements of causality for an ultrarelativistic beam.

  13. Graphene Quantum Capacitors for High Frequency Tunable Analog Applications.

    PubMed

    Moldovan, Clara F; Vitale, Wolfgang A; Sharma, Pankaj; Tamagnone, Michele; Mosig, Juan R; Ionescu, Adrian M

    2016-08-10

    Graphene quantum capacitors (GQC) are demonstrated to be enablers of radio-frequency (RF) functions through voltage-tuning of their capacitance. We show that GQC complements MEMS and MOSFETs in terms of performance for high frequency analog applications and tunability. We propose a CMOS compatible fabrication process and report the first experimental assessment of their performance at microwaves frequencies (up to 10 GHz), demonstrating experimental GQCs in the pF range with a tuning ratio of 1.34:1 within 1.25 V, and Q-factors up to 12 at 1 GHz. The figures of merit of graphene variable capacitors are studied in detail from 150 to 350 K. Furthermore, we describe a systematic, graphene specific approach to optimize their performance and predict the figures of merit achieved if such a methodology is applied.

  14. High frequency sound propagation in a network of interconnecting streets

    NASA Astrophysics Data System (ADS)

    Hewett, D. P.

    2012-12-01

    We propose a new model for the propagation of acoustic energy from a time-harmonic point source through a network of interconnecting streets in the high frequency regime, in which the wavelength is small compared to typical macro-lengthscales such as street widths/lengths and building heights. Our model, which is based on geometrical acoustics (ray theory), represents the acoustic power flow from the source along any pathway through the network as the integral of a power density over the launch angle of a ray emanating from the source, and takes into account the key phenomena involved in the propagation, namely energy loss by wall absorption, energy redistribution at junctions, and, in 3D, energy loss to the atmosphere. The model predicts strongly anisotropic decay away from the source, with the power flow decaying exponentially in the number of junctions from the source, except along the axial directions of the network, where the decay is algebraic.

  15. High-frequency radar observations of ocean surface currents.

    PubMed

    Paduan, Jeffrey D; Washburn, Libe

    2013-01-01

    This article reviews the discovery, development, and use of high-frequency (HF) radio wave backscatter in oceanography. HF radars, as the instruments are commonly called, remotely measure ocean surface currents by exploiting a Bragg resonant backscatter phenomenon. Electromagnetic waves in the HF band (3-30 MHz) have wavelengths that are commensurate with wind-driven gravity waves on the ocean surface; the ocean waves whose wavelengths are exactly half as long as those of the broadcast radio waves are responsible for the resonant backscatter. Networks of HF radar systems are capable of mapping surface currents hourly out to ranges approaching 200 km with a horizontal resolution of a few kilometers. Such information has many uses, including search and rescue support and oil-spill mitigation in real time and larval population connectivity assessment when viewed over many years. Today, HF radar networks form the backbone of many ocean observing systems, and the data are assimilated into ocean circulation models.

  16. High-frequency health data and spline functions.

    PubMed

    Martín-Rodríguez, Gloria; Murillo-Fort, Carlos

    2005-03-30

    Seasonal variations are highly relevant for health service organization. In general, short run movements of medical magnitudes are important features for managers in this field to make adequate decisions. Thus, the analysis of the seasonal pattern in high-frequency health data is an appealing task. The aim of this paper is to propose procedures that allow the analysis of the seasonal component in this kind of data by means of spline functions embedded into a structural model. In the proposed method, useful adaptions of the traditional spline formulation are developed, and the resulting procedures are capable of capturing periodic variations, whether deterministic or stochastic, in a parsimonious way. Finally, these methodological tools are applied to a series of daily emergency service demand in order to capture simultaneous seasonal variations in which periods are different.

  17. Classification of high frequency oscillations in epileptic intracerebral EEG.

    PubMed

    Jrad, Nisrine; Kachenoura, Amar; Merlet, Isabelle; Nica, Anca; Benar, Christian G; Wendling, Fabrice

    2015-08-01

    High Frequency Oscillations (HFOs 40-500 Hz), recorded from intracerebral electroencephalography (iEEG) in epileptic patients, are categorized into four distinct sub-bands (Gamma, High-Gamma, Ripples and Fast Ripples). They have recently been used as a reliable biomarker of epileptogenic zones. The objective of this paper is to investigate the possibility of discriminating between the different classes of HFOs which physiological/pathological value is critical for diagnostic but remains to be clarified. The proposed method is based on the definition of a relevant feature vector built from energy ratios (computed using Wavelet Transform-WT) in a-priori-defined frequency bands. It makes use of a multiclass Linear Discriminant Analysis (LDA) and is applied to iEEG signals recorded in patients candidate to epilepsy surgery. Results obtained from bootstrap on training/test datasets indicate high performances in terms of sensitivity and specificity.

  18. High-Frequency Cutoff in Type III Bursts

    NASA Astrophysics Data System (ADS)

    Stanislavsky, A. A.; Konovalenko, A. A.; Volvach, Ya. S.; Koval, A. A.

    In this article we report about a group of solar bursts with high-frequency cutoff, observed on 19 August of 2012 near 8:23 UT, simultaneously by three different radio telescopes: the Ukrainian decameter radio telescope (8-33 MHz), the French Nancay Decametric Array (10-70 MHz) and the Italian San Vito Solar Observatory of RSTN (25-180 MHz). Morphologically the bursts are very similar to the type III bursts. The solar activity is connected with the emergency of a new group of solar spots on the far side of the Sun with respect to observers on Earth. The solar bursts accompany many moderate flares over eastern limb. The refraction of the behind-limb radio bursts towards the Earth is favorable, if CMEs generate low-density cavities in solar corona.

  19. High-frequency EPR study of crude oils

    NASA Astrophysics Data System (ADS)

    Volodin, M. A.; Mamin, G. V.; Izotov, V. V.; Orlinskii, S. B.

    2013-12-01

    Four different samples of crude oil were studied by means of high-frequency W-band (94 GHz) electron paramagnetic resonance (EPR) spectroscopy with the aim to develop new methods of crude oil quality control. High spectral resolution of W-band allowed to avoid an overlap of spectra contributors. The ratio K between the integral intensity of the low-field EPR component of the vanadyl complexes to that of free radical line was chosen as an attribute of each sample. Using the K-parameters and EPR spectra simulations the crude oil leaking between adjacent horizons is shown. Pulsed EPR experiments allowed detecting free radicals signals only. It is demonstrated that the extracted transverse relaxation time could be used as an additional parameter which characterizes the origin of the crude oil and nature of the oil paramagnetic centers.

  20. High-frequency underwater plasma discharge application in antibacterial activity

    NASA Astrophysics Data System (ADS)

    Ahmed, M. W.; Choi, S.; Lyakhov, K.; Shaislamov, U.; Mongre, R. K.; Jeong, D. K.; Suresh, R.; Lee, H. J.

    2017-03-01

    Plasma discharge is a novel disinfection and effectual inactivation approach to treat microorganisms in aqueous systems. Inactivation of Gram-negative Escherichia coli (E. coli) by generating high-frequency, high-voltage, oxygen (O2) injected and hydrogen peroxide (H2O2) added discharge in water was achieved. The effect of H2O2 dose and oxygen injection rate on electrical characteristics of discharge and E. coli disinfection has been reported. Microbial log reduction dependent on H2O2 addition with O2 injection was observed. The time variation of the inactivation efficiency quantified by the log reduction of the initial E. coli population on the basis of optical density measurement was reported. The analysis of emission spectrum recorded after discharge occurrence illustrated the formation of oxidant species (OH•, H, and O). Interestingly, the results demonstrated that O2 injected and H2O2 added, underwater plasma discharge had fabulous impact on the E. coli sterilization. The oxygen injection notably reduced the voltage needed for generating breakdown in flowing water and escalated the power of discharge pulses. No impact of hydrogen peroxide addition on breakdown voltage was observed. A significant role of oxidant species in bacterial inactivation also has been identified. Furthermore the E. coli survivability in plasma treated water with oxygen injection and hydrogen peroxide addition drastically reduced to zero. The time course study also showed that the retardant effect on E. coli colony multiplication in plasma treated water was favorable, observed after long time. High-frequency underwater plasma discharge based biological applications is technically relevant and would act as baseline data for the development of novel antibacterial processing strategies.

  1. Electrokinetic particle-electrode interactions at high frequencies

    NASA Astrophysics Data System (ADS)

    Yariv, Ehud; Schnitzer, Ory

    2013-01-01

    We provide a macroscale description of electrokinetic particle-electrode interactions at high frequencies, where chemical reactions at the electrodes are negligible. Using a thin-double-layer approximation, our starting point is the set of macroscale equations governing the “bounded” configuration comprising of a particle suspended between two electrodes, wherein the electrodes are governed by a capacitive charging condition and the imposed voltage is expressed as an integral constraint. In the large-cell limit the bounded model is transformed into an effectively equivalent “unbounded” model describing the interaction between the particle and a single electrode, where the imposed-voltage condition is manifested in a uniform field at infinity together with a Robin-type condition applying at the electrode. This condition, together with the standard no-flux condition applying at the particle surface, leads to a linear problem governing the electric potential in the fluid domain in which the dimensionless frequency ω of the applied voltage appears as a governing parameter. In the high-frequency limit ω≫1 the flow is dominated by electro-osmotic slip at the particle surface, the contribution of electrode electro-osmosis being O(ω-2) small. That simplification allows for a convenient analytical investigation of the prevailing case where the clearance between the particle and the adjacent electrode is small. Use of tangent-sphere coordinates allows to calculate the electric and flows fields as integral Hankel transforms. At large distances from the particle, along the electrode, both fields decay with the fourth power of distance.

  2. High-frequency underwater plasma discharge application in antibacterial activity

    NASA Astrophysics Data System (ADS)

    Ahmed, M. W.; Choi, S.; Lyakhov, K.; Shaislamov, U.; Mongre, R. K.; Jeong, D. K.; Suresh, R.; Lee, H. J.

    2017-03-01

    Plasma discharge is a novel disinfection and effectual inactivation approach to treat microorganisms in aqueous systems. Inactivation of Gram-negative Escherichia coli ( E. coli) by generating high-frequency, high-voltage, oxygen (O2) injected and hydrogen peroxide (H2O2) added discharge in water was achieved. The effect of H2O2 dose and oxygen injection rate on electrical characteristics of discharge and E. coli disinfection has been reported. Microbial log reduction dependent on H2O2 addition with O2 injection was observed. The time variation of the inactivation efficiency quantified by the log reduction of the initial E. coli population on the basis of optical density measurement was reported. The analysis of emission spectrum recorded after discharge occurrence illustrated the formation of oxidant species (OH•, H, and O). Interestingly, the results demonstrated that O2 injected and H2O2 added, underwater plasma discharge had fabulous impact on the E. coli sterilization. The oxygen injection notably reduced the voltage needed for generating breakdown in flowing water and escalated the power of discharge pulses. No impact of hydrogen peroxide addition on breakdown voltage was observed. A significant role of oxidant species in bacterial inactivation also has been identified. Furthermore the E. coli survivability in plasma treated water with oxygen injection and hydrogen peroxide addition drastically reduced to zero. The time course study also showed that the retardant effect on E. coli colony multiplication in plasma treated water was favorable, observed after long time. High-frequency underwater plasma discharge based biological applications is technically relevant and would act as baseline data for the development of novel antibacterial processing strategies.

  3. The Influence of High-Frequency Gravitational Waves Upon Muscles

    SciTech Connect

    Moy, Lawrence S.; Baker, Robert M. L. Jr

    2007-01-30

    The objective of this paper is to present a theory for the possible influence of high-frequency gravitational waves or HFGWs and pulsed micro-current electromagnetic waves or EMs on biological matter specifically on muscle cells and myofibroblasts. The theory involves consideration of the natural frequency of contractions and relaxations of muscles, especially underlying facial skin, and the possible influence of HFGWs on that process. GWs pass without attenuation through all material thus conventional wisdom would dictate that GWs would have no influence on biological matter. On the other hand, GWs can temporarily modify a gravitational field in some locality if they are of high frequency and such a modification might have an influence in changing the skin muscles' natural frequency. Prior to the actual laboratory generation of HFGWs their influence can be emulated by micro-current EM pulses to the skin and some evidence presented here on that effect may predict the influence of HFGWs. We believe that the HFGW pulsations lead to increased muscle activity and may serve to reverse the aging process. A novel theoretical framework concerning these relaxation phenomena is one result of the paper. Another result is the analysis of the possible delivery system of the FBAR-generated HFGWs, the actual power of the generated HFGWs, and the system's application to nanostructural modification of the skin or muscle cells. It is concluded that a series of non-evasive experiments, which are identified, will have the potential to test theory by detecting and analyzing the possible HFGWs change in polarization, refraction, etc. after their interaction with the muscle cells.

  4. High frequency acoustic reflections from an air-snow interface

    NASA Astrophysics Data System (ADS)

    Courville, Z.; Albert, D. G.; Lieb-Lappen, R.; Fegyveresi, J. M.

    2016-12-01

    High frequency wave propagation methods can be used to determine in situ near surface micro-pore geometry parameters in real Earth materials including snow. To this end, we have been developing a portable ultrasonic transducer rig to make measurements of acoustic reflections from a variety of natural porous media. Fresh natural snow, in particular, is a difficult material to characterize, as any mechanical interaction is likely to damage the fragile pores and grain bonds. Because acoustic waves are sensitive to the porous material properties, they potentially can be used to measure snow properties in a non-destructive manner. Such methods have already been demonstrated on cohesive porous materials including manufactured foams, porous metals, and sintered glass beads. We conducted high frequency, oblique-angle and near vertical reflection measurements on snow samples in a cold room. We then compare the acoustically derived snow physical parameters, including porosity, with values determined from micro-computed tomography (μCT) and with standard (but destructive) laboratory measurements. Preliminary results using a manufactured open cell foam following previous work by Fellah et al., (2003) shows very good agreement between values of porosity determined from the acoustic measurements and the values determined from μCT image analysis and gravimetric determination. Similarly, preliminary results comparing acoustic measurements of natural, dry snow samples prepared in the laboratory show good agreement between acoustically-derived porosity values and porosity values derived through independent means. Fellah, Z.E.A., S. Berger, W. Lauriks, C. Depollier, C. Aristegui, and J.Y. Chapelon, (2003b), Measuring the porosity and tortuosity of porous materials via reflected waves at oblique incidence, J. Acous. Soc. Am., 113, 2424-2433.

  5. Development of a Multi-Channel, High Frequency QRS Electrocardiograph

    NASA Technical Reports Server (NTRS)

    DePalma, Jude L.

    2003-01-01

    With the advent of the ISS era and the potential requirement for increased cardiovascular monitoring of crewmembers during extended EVAs, NASA flight surgeons would stand to benefit from an evolving technology that allows for a more rapid diagnosis of myocardial ischemia compared to standard electrocardiography. Similarly, during the astronaut selection process, NASA flight surgeons and other physicians would also stand to benefit from a completely noninvasive technology that, either at rest or during maximal exercise tests, is more sensitive than standard ECG in identifying the presence of ischemia. Perhaps most importantly, practicing cardiologists and emergency medicine physicians could greatly benefit from such a device as it could augment (or even replace) standard electrocardiography in settings where the rapid diagnosis of myocardial ischemia (or the lack thereof) is required for proper clinical decision-making. A multi-channel, high-frequency QRS electrocardiograph is currently under development in the Life Sciences Research Laboratories at JSC. Specifically the project consisted of writing software code, some of which contained specially-designed digital filters, which will be incorporated into an existing commercial software program that is already designed to collect, plot and analyze conventional 12-lead ECG signals on a desktop, portable or palm PC. The software will derive the high-frequency QRS signals, which will be analyzed (in numerous ways) and plotted alongside of the conventional ECG signals, giving the PC-viewing clinician advanced diagnostic information that has never been available previously in all 12 ECG leads simultaneously. After the hardware and software for the advanced digital ECG monitor have been fully integrated, plans are to use the monitor to begin clinical studies both on healthy subjects and on patients with known coronary artery disease in both the outpatient and hospital settings. The ultimate goal is to get the technology

  6. High Frequency Monitoring System of Groundwater Level in Sheliao

    NASA Astrophysics Data System (ADS)

    Lee, C.; Chia, Y.; Chuang, P.

    2012-12-01

    Long-term groundwater monitoring had been executed since 1950s in Taiwan. In 1980s, with improving technology, various types of automatic reorders of groundwater level had become the most widely used equipment in groundwater monitoring. Among these devices, submersible pressure transducer is frequently selected to monitor groundwater level for its high frequency and high resolution. In this study, it is chosen to monitor groundwater level change in Sheliao well. On the other hand, factors which might influence the performance of recorded data were excluded in the early stage of establishment as well. And the final approach is to achieve a comprehensive understanding of the minor groundwater level change of Sheliao well, and specify its connection between precipitation, atmosphere, earth tide and earthquake. The Shelia well is located in central Taiwan, constructed in an unconfined aquifer, recorded hourly groundwater level change since 1997. We tried to establish a 1 Hz sampling rate pressure-sensing system in 2011 June. The groundwater level was monitored in a resolution of 2-mm. According to the records, several small-scale of fluctuations were observed and were all correlate well to the earthquakes. However, during the time that no earthquake occurred, some short-term fluctuations were still occurred, performed in a different pattern to those induced by earthquakes. After further investigation, those anomalous fluctuations of groundwater level were found corresponded to precipitation quite well. The fluctuations were observed under some specific condition, which involving different range of accumulated precipitation, rainfall intensity, and rainfall duration. The result implied groundwater level in Sheliao well changes with loading effect result from runoff on the ground surface and infiltration. And the earth tide lead to regularly change was also observed. We conclude that Sheliao can be characterized as a partial-confined aquifer with high frequency and high

  7. Sensitivity of high-frequency Rayleigh-wave data revisited

    USGS Publications Warehouse

    Xia, J.; Miller, R.D.; Ivanov, J.

    2007-01-01

    Rayleigh-wave phase velocity of a layered earth model is a function of frequency and four groups of earth properties: P-wave velocity, S-wave velocity (Vs), density, and thickness of layers. Analysis of the Jacobian matrix (or the difference method) provides a measure of dispersion curve sensitivity to earth properties. Vs is the dominant influence for the fundamental mode (Xia et al., 1999) and higher modes (Xia et al., 2003) of dispersion curves in a high frequency range (>2 Hz) followed by layer thickness. These characteristics are the foundation of determining S-wave velocities by inversion of Rayleigh-wave data. More applications of surface-wave techniques show an anomalous velocity layer such as a high-velocity layer (HVL) or a low-velocity layer (LVL) commonly exists in near-surface materials. Spatial location (depth) of an anomalous layer is usually the most important information that surface-wave techniques are asked to provide. Understanding and correctly defining the sensitivity of high-frequency Rayleigh-wave data due to depth of an anomalous velocity layer are crucial in applying surface-wave techniques to obtain a Vs profile and/or determine the depth of an anomalous layer. Because depth is not a direct earth property of a layered model, changes in depth will result in changes in other properties. Modeling results show that sensitivity at a given depth calculated by the difference method is dependent on the Vs difference (contrast) between an anomalous layer and surrounding layers. The larger the contrast is, the higher the sensitivity due to depth of the layer. Therefore, the Vs contrast is a dominant contributor to sensitivity of Rayleigh-wave data due to depth of an anomalous layer. Modeling results also suggest that the most sensitive depth for an HVL is at about the middle of the depth to the half-space, but for an LVL it is near the ground surface. ?? 2007 Society of Exploration Geophysicists.

  8. Compact Infrared Spectrometers

    NASA Technical Reports Server (NTRS)

    Mouroulis, Pantazis

    2009-01-01

    Concentric spectrometer forms are advantageous for constructing a variety of systems spanning the entire visible to infrared range. Spectrometer examples are given, including broadband or high resolution forms. Some issues associated with the Dyson catadioptric type are also discussed.

  9. Electronics for a Spectrometer

    NASA Image and Video Library

    2014-01-24

    NASA has provided part of the electronics package for an instrument called the Double Focusing Mass Spectrometer, which is part of the Swiss-built Rosetta Orbiter Spectrometer for Ion and Neutral Analysis ROSINA instrument.

  10. Compact Infrared Spectrometers

    NASA Technical Reports Server (NTRS)

    Mouroulis, Pantazis

    2009-01-01

    Concentric spectrometer forms are advantageous for constructing a variety of systems spanning the entire visible to infrared range. Spectrometer examples are given, including broadband or high resolution forms. Some issues associated with the Dyson catadioptric type are also discussed.

  11. Direct recoil oxygen ion fractions resulting from Ar + collisions

    NASA Astrophysics Data System (ADS)

    Chen, Jie-Nan; Rabalais, J. Wayne

    1986-03-01

    Direct recoil of oxygen from oxidized and hydroxylated magnesium surfaces as a result of 6 keV Ar + collisions produces O -, O +, and O species. The total ion fraction at a recoil angle of 22° is ~33.5%, of which O - is 23.7% and O + is 9.8% for the oxidized surface. The O -/O + intensity ratio is extremely sensitive to the amount of hydrogen present, with the O + yield dropping to ~1% on the hydroxylated surface. These results are considered within a model for electronic transitions in ion/surface collisions which considers Auger and resonant transitions along the ion trajectory and electron promotions in the quasi-diatomic molecule of the close encounter.

  12. The new vacuum-mode recoil separator MARA at JYFL

    NASA Astrophysics Data System (ADS)

    Sarén, J.; Uusitalo, J.; Leino, M.; Greenlees, P. T.; Jakobsson, U.; Jones, P.; Julin, R.; Juutinen, S.; Ketelhut, S.; Nyman, M.; Peura, P.; Rahkila, P.; Scholey, C.; Sorri, J.

    2008-10-01

    A new vacuum-mode recoil separator MARA (Mass Analysing Recoil Apparatus) is under design and construction at the Department of Physics in the University of Jyväskylä. The separator is intended to separate reaction products from the primary beam in mass region below A = 150 . The ion-optical configuration of the separator will be QQQDEDM, where a magnetic quadrupole (Q) triplet is followed by an electrostatic deflector (DE) and a magnetic dipole (DM). The total length of MARA will be less than 7.0 m and the first order resolving power more than 250 for a beam spot size of 2 mm. In this contribution the main properties of MARA are given and results from simulations are shown.

  13. Recoil detection of the lightest neutralino in MSSM singlet extensions

    SciTech Connect

    Barger, Vernon; Lewis, Ian; McCaskey, Mat; Shaughnessy, Gabe; Yencho, Brian; Langacker, Paul

    2007-06-01

    We investigate the correlated predictions of singlet extended MSSM models for direct detection and the cosmological relic density of the lightest neutralino. To illustrate the general effects of the singlet, we take heavy sleptons and squarks. We apply CERN LEP (g-2){sub {mu}}, and perturbativity constraints. We find that the WMAP upper bound on the cold dark matter density limits much of the parameter space to regions where the lightest neutralino can be discovered in recoil experiments. The results for the next-to-minimal supersymmetric standard model and U(1){sup '}-extended minimal supersymmetric standard model are typically similar to the MSSM since their light neutralinos have similar compositions and masses. In the nearly minimal supersymmetric standard model the neutralino is often very light and its recoil detection is within the reach of the CDMS II experiment. In general, most points in the parameter spaces of the singlet models we consider are accessible to the WARP experiment.

  14. First detection of radon progeny recoil tracks by MIMAC

    NASA Astrophysics Data System (ADS)

    Riffard, Q.; Santos, D.; Guillaudin, O.; Bosson, G.; Bourrion, O.; Bouvier, J.; Descombes, T.; Fourel, C.; Muraz, J.-F.; Lebreton, L.; Maire, D.; Colas, P.; Ferrer-Ribas, E.; Giomataris, I.; Busto, J.; Fouchez, D.; Brunner, J.; Tao, C.

    2017-06-01

    The MIMAC experiment is a μ-TPC project for directional dark matter search. Directional detection strategy is based on the measurement of the WIMP flux anisotropy due to the solar system motion with respect to the dark matter halo. The main purpose of MIMAC project is the measurement of nuclear recoil energy and 3D direction from the WIMP elastic scattering on target nuclei. Since June 2012 a bi-chamber prototype is operating at the Modane underground laboratory. In this paper, we report the first ionization energy and 3D track observations of NRs produced by the radon progeny. This measurement shows the capability of the MIMAC detector and opens the possibility to explore the low energy recoil directionality signature.

  15. Recoiling supermassive black holes: a search in the nearby universe

    SciTech Connect

    Lena, D.; Robinson, A.; Axon, D. J.; Merritt, D.; Marconi, A.; Capetti, A.; Batcheldor, D.

    2014-11-10

    The coalescence of a binary black hole can be accompanied by a large gravitational recoil due to anisotropic emission of gravitational waves. A recoiling supermassive black hole (SBH) can subsequently undergo long-lived oscillations in the potential well of its host galaxy, suggesting that offset SBHs may be common in the cores of massive ellipticals. We have analyzed Hubble Space Telescope archival images of 14 nearby core ellipticals, finding evidence for small (≲ 10 pc) displacements between the active galactic nucleus (AGN; the location of the SBH) and the center of the galaxy (the mean photocenter) in 10 of them. Excluding objects that may be affected by large-scale isophotal asymmetries, we consider six galaxies to have detected displacements, including M87, where a displacement was previously reported by Batcheldor et al. In individual objects, these displacements can be attributed to residual gravitational recoil oscillations following a major or minor merger within the last few gigayears. For plausible merger rates, however, there is a high probability of larger displacements than those observed, if SBH coalescence took place in these galaxies. Remarkably, the AGN-photocenter displacements are approximately aligned with the radio source axis in four of the six galaxies with displacements, including three of the four having relatively powerful kiloparsec-scale jets. This suggests intrinsic asymmetries in radio jet power as a possible displacement mechanism, although approximate alignments are also expected for gravitational recoil. Orbital motion in SBH binaries and interactions with massive perturbers can produce the observed displacement amplitudes but do not offer a ready explanation for the alignments.

  16. Recoiling Supermassive Black Holes: a search in the Nearby Universe

    NASA Astrophysics Data System (ADS)

    Lena, Davide; Robinson, Andrew; Marconi, Alessandro; Axon, David; Capetti, Alessandro; Merritt, David; Batcheldor, Daniel

    2015-01-01

    The coalescence of a binary black hole can be accompanied by a large gravitational recoil due to anisotropic emission of gravitational waves. A recoiling supermassive black hole (SBH) can subsequently undergo long-lived oscillations in the potential well of its host galaxy, suggesting that offset SBHs may be common in the cores of massive ellipticals. We have analyzed HST archival images of 14 nearby core ellipticals, finding evidence for small (<=10 pc) displacements between the AGN (locating the SBH) and the center of the galaxy (the mean photocenter) in 10 of them. Excluding objects that may be affected by large-scale isophotal asymmetries, we consider six galaxies to have detected displacements, including M87, where a displacement was previously reported by Batcheldor et al. 2010. In individual objects, these displacements can be attributed to residual gravitational recoil oscillations following a major or minor merger within the last few Gyr. For plausible merger rates, however, there is a high probability of larger displacements than those observed, if SBH coalescence took place in these galaxies. Remarkably, the AGN-photocenter displacements are approximately aligned with the radio source axis in four of the six galaxies with displacements, including three of the four having relatively powerful kpc-scale jets. This suggests intrinsic asymmetries in radio jet power as a possible displacement mechanism, although approximate alignments are also expected for gravitational recoil. Orbital motion in SBH binaries and interactions with massive perturbers can produce the observed displacement amplitudes but do not offer a ready explanation for the alignments.

  17. Recoiling Supermassive Black Holes: A Search in the Nearby Universe

    NASA Astrophysics Data System (ADS)

    Lena, D.; Robinson, A.; Marconi, A.; Axon, D. J.; Capetti, A.; Merritt, D.; Batcheldor, D.

    2014-11-01

    The coalescence of a binary black hole can be accompanied by a large gravitational recoil due to anisotropic emission of gravitational waves. A recoiling supermassive black hole (SBH) can subsequently undergo long-lived oscillations in the potential well of its host galaxy, suggesting that offset SBHs may be common in the cores of massive ellipticals. We have analyzed Hubble Space Telescope archival images of 14 nearby core ellipticals, finding evidence for small (lsim 10 pc) displacements between the active galactic nucleus (AGN; the location of the SBH) and the center of the galaxy (the mean photocenter) in 10 of them. Excluding objects that may be affected by large-scale isophotal asymmetries, we consider six galaxies to have detected displacements, including M87, where a displacement was previously reported by Batcheldor et al. In individual objects, these displacements can be attributed to residual gravitational recoil oscillations following a major or minor merger within the last few gigayears. For plausible merger rates, however, there is a high probability of larger displacements than those observed, if SBH coalescence took place in these galaxies. Remarkably, the AGN-photocenter displacements are approximately aligned with the radio source axis in four of the six galaxies with displacements, including three of the four having relatively powerful kiloparsec-scale jets. This suggests intrinsic asymmetries in radio jet power as a possible displacement mechanism, although approximate alignments are also expected for gravitational recoil. Orbital motion in SBH binaries and interactions with massive perturbers can produce the observed displacement amplitudes but do not offer a ready explanation for the alignments.

  18. Passive mechanism of pitch recoil in flapping insect wings.

    PubMed

    Ishihara, D; Horie, T

    2016-12-20

    The high torsional flexibility of insect wings allows for elastic recoil after the rotation of the wing during stroke reversal. However, the underlying mechanism of this recoil remains unclear because of the dynamic process of transitioning from the wing rotation during stroke reversal to the maintenance of a high angle of attack during the middle of each half-stroke, when the inertial, elastic, and aerodynamic effects all have a significant impact. Therefore, the interaction between the flapping wing and the surrounding air was directly simulated by simultaneously solving the incompressible Navier-Stokes equations, the equation of motion for an elastic body, and the fluid-structure interface conditions using the three-dimensional finite element method. This direct numerical simulation controlling the aerodynamic effect revealed that the recoil is the residual of the free pitch vibration induced by the flapping acceleration during stroke reversal in the transient response very close to critical damping due to the dynamic pressure resistance of the surrounding air. This understanding will enable the control of the leading-edge vortex and lift generation, the reduction of the work performed by flapping wings, and the interpretation of the underlying necessity for the kinematic characteristics of the flapping motion.

  19. Recoiling from a Kick in the Head-On Case

    NASA Technical Reports Server (NTRS)

    Choi, Dae-Il; Kelly, Bernard J.; Boggs, William D.; Baker, John G.; Centrella, Joan; Van Meter, James

    2007-01-01

    Recoil "kicks" induced by gravitational radiation are expected in the inspiral and merger of black holes. Recently the numerical relativity community has begun to measure the significant kicks found when both unequal masses and spins are considered. Because understanding the cause and magnitude of each component of this kick may be complicated in inspiral simulations, we consider these effects in the context of a simple test problem. We study recoils from collisions of binaries with initially head-on trajectories, starting with the simplest case of equal masses with no spin; adding spin and varying the mass ratio, both separately and jointly. We find spin-induced recoils to be significant even in head-on configurations. Additionally, it appears that the scaling of transverse kicks with spins is consistent with post-Newtonian (PN) theory, even though the kick is generated in the nonlinear merger interaction, where PN theory should not apply. This suggests that a simple heuristic description might be effective in the estimation of spin-kicks.

  20. Anatomy of the Binary Black Hole Recoil: A Multipolar Analysis

    NASA Technical Reports Server (NTRS)

    Schnittman, Jeremy; Buonanno, Alessandra; vanMeter, James R.; Baker, John G.; Boggs, William D.; Centrella, Joan; Kelly, Bernard J.; McWilliams, Sean T.

    2007-01-01

    We present a multipolar analysis of the recoil velocity computed in recent numerical simulations of binary black hole coalescence, for both unequal masses and non-zero, non-precessing spins. We show that multipole moments up to and including 1 = 4 are sufficient to accurately reproduce the final recoil velocity (= 98%) and that only a few dominant modes contribute significantly to it (2 95%). We describe how the relative amplitude, and more importantly, the relative phase, of these few modes control the way in which the recoil builds up throughout the inspiral, merger, and ring-down phases. We also find that the numerical results can be reproduced, to a high level of accuracy, by an effective Newtonian formula for the multipole moments obtained by replacing in the Newtonian formula the radial separation with an effective radius computed from the numerical data. Beyond the merger, the numerical results are reproduced by a superposition of three Kerr quasi-normal modes. Analytic formulae, obtained by expressing the multipole moments in terms of the fundamental QNMs of a Kerr BH, are able to explain the onset and amount of '.anti-kick" for each of the simulations. Lastly, we apply this multipolar analysis to understand the remarkable difference between the amplitudes of planar and non-planar kicks for equal-mass spinning black holes.

  1. Recoil-induced Resonances as All-optical Switches

    NASA Astrophysics Data System (ADS)

    Narducci, F. A.; Desavage, S. A.; Gordon, K. H.; Duncan, D. L.; Welch, G. R.; Davis, J. P.

    2010-03-01

    We have measured recoil-induced resonances (RIR) [1,2] in our system of laser-cooled 85Rb atoms. Although this technique has been demonstrated to be useful for the purpose of extracting the cloud temperature [3], our aim was to demonstrate an all optical switch based on recoil-induced resonances. In addition to a very narrow ``free-space'' recoil-induced resonance of approximately 15 kHz, we also discovered a much broader resonance (˜30 MHz), caused by standing waves established by our trapping fields. We compare and contrast the switching dynamics of these two resonances and demonstrate optical switching using both resonances. Finally, we consider the applicability of the narrow, free-space resonance to the slowing of a weak probe field. [1] J. Guo, P.R. Berman, B. Dubetsky and G. Grynberg PRA, 46, 1426 (1992). [2] (a) P. Verkerk, B. Loumis, C. Salomon, C. Cohen-Tannoudji, J. Courtois PRL, 68, 3861 (1992). (b) G. Grynberg, J-Y Courtois, B. Lounis, P. Verkerk PRL, 72, 3017 (1994). [3] (a) T. Brzozowski, M. Brzozowska, J. Zachorowski, M. Zawada, W. Gawlik PRA, 71, 013401 (2005). (b) M. Brzozowska, T. Brzozowski J. Zachorowski, W. Gawlik PRA, 72, 061401(R), (2005).

  2. Experimental study of a very high frequency, 162 MHz, segmented electrode, capacitively coupled plasma discharge

    NASA Astrophysics Data System (ADS)

    Sirse, Nishant; Harvey, Cleo; Gaman, Cezar; Ellingboe, Bert

    2016-09-01

    Radio-frequency capacitively coupled plasma (CCP) discharge operating at a very high frequency, 30-300 MHz, offers many advantages over standard 13.56 MHz CCP. However, there is a limited flexibility on the choice of driving frequency and substrate size due to plasma non-uniformity caused by the standing wave effect and edge effect. To overcome this issue segmented electrode CCP's are proposed and researched. Despite its numerous advantages the power coupling mechanism and plasma chemistry in this type of discharge are not fully understood due to lack of experimental data. In this paper, we present the experimental study of a segmented electrode, 3x4 tile array (10x10 cm square tile with 1 cm tile-to-tile separation), CCP discharge driven at 162 MHz. We measured plasma uniformity and gas temperature using hairpin probe and optical emission spectroscopy respectively. A homemade RF compensated Langmuir probe is employed to measure the Electron Energy Distribution Function (EEDF) by second harmonic technique. Energy resolved quadrupole mass spectrometer is utilized to measure the ion energy distribution. Discharge/plasma properties are investigated for several operating conditions and for power coupling mode in both washer board and checker board configuration. The experimental results show that the uniform plasma density can be maintained over a large area along with highly non-equilibrium condition to produce unique gas phase plasma chemistry.

  3. FTIR Analysis of Flowing Afterglow from a High-Frequency Spark Discharge

    NASA Astrophysics Data System (ADS)

    White, Allen; Hieftje, Gary M.; Ray, Steve; Pfeuffer, Kevin

    2014-06-01

    Plasmas are often used as ionization sources for ambient mass spectrometry (AMS). Here, the flowing afterglow of a novel high-energy spark discharge system, operated in nitrogen at high repetition rates, is investigated as a source for AMS. The spark discharge here is the same as that of an automobile ignition circuit.Combustion in automobile engines is initiated by a spark ignition system that is designed to deliver short-duration,high-voltage sparks to multiple engine cylinders. The arrangement utilized in this study is a modified discharge configuration designed to produce similarly short-duration, high-voltage discharges. It consists of an automotive ignition coil that is activated by a spark initiation circuit that discharges in turn into a cell with neutral gas input flow and ultimately into the collection orifice of a mass spectrometer. The discharge voltage is approximately 40kV at 800 Hz. High-frequency spark discharges in a nitrogen flow produce reagent ions such as NO+. In order to better evaluate the effectiveness of the discharge in producing reagent ions, an FTIR is utilized to measure IR active species such as nitric oxide, hydroxide, ozone, and water in the afterglow of the spark discharge during variation of discharge parameters. Time-resolved IR emission spectra provide additional insight into the reagent ion production mechanisms.

  4. Towards in situ and high frequency estimates of suspended sediment properties

    NASA Astrophysics Data System (ADS)

    Martínez-Carreras, Núria; Schwab, Michael Peter; Klaus, Julian; Hissler, Christophe

    2016-04-01

    Sediment properties, including sediment-associated chemical constituents and sediment physical properties (as colour), can exhibit significant variations within and between storm runoff events. However, the number of samples included in suspended sediment studies is often limited by the time consuming and expensive laboratory procedures for suspended sediment analysis after stream water sampling. This, in turn, restricts high frequency sampling campaigns to a limited number of events and reduces accuracy when aiming to estimate fluxes and loads of sediment-associated chemical constituents. Our contribution addresses the potential for portable ultraviolet-visible (UV-VIS) light spectrometers (220-730 nm) to estimate suspended sediment properties in situ and at high temporal resolution. As far as we know, these instruments have primarily been developed and used to quantify solute concentrations (e.g. DOC and NO3-N), total concentrations of dissolved and particulate forms (e.g. TOC) and turbidity. Here we argue that light absorbance values can be calibrated to estimate solely sediment properties. For our proof-of-concept experiment, we measured light absorbance at 15-min intervals at the Weierbach catchment (NW Luxembourg, 0.46 km2) from December 2013 to January 2015. We then performed a local calibration using suspended sediment loss-on-ignition (LOI) measurements (n=34). We assessed the performance of several regression models that relate light absorbance measurements with the percentage weight LOI. The robust regression method presented the lowest standard error of prediction (0.48{%}) and was selected for calibration (adjusted r2 = 0.76 between observed and predicted values). This study demonstrates that spectrometers can be used to estimate suspended sediment properties at high temporal resolution and for long time spans in a simple, non-destructive and affordable manner. The advantages and disadvantages of the method compared to traditional approaches will be

  5. High-Frequency Nanocapacitor Arrays: Concept, Recent Developments, and Outlook.

    PubMed

    Lemay, Serge G; Laborde, Cecilia; Renault, Christophe; Cossettini, Andrea; Selmi, Luca; Widdershoven, Frans P

    2016-10-18

    We have developed a measurement platform for performing high-frequency AC detection at nanoelectrodes. The system consists of 65 536 electrodes (diameter 180 nm) arranged in a sub-micrometer rectangular array. The electrodes are actuated at frequencies up to 50 MHz, and the resulting AC current response at each separately addressable electrode is measured in real time. These capabilities are made possible by fabricating the electrodes on a complementary metal-oxide-semiconductor (CMOS) chip together with the associated control and readout electronics, thus minimizing parasitic capacitance and maximizing the signal-to-noise ratio. This combination of features offers several advantages for a broad range of experiments. First, in contrast to alternative CMOS-based electrical systems based on field-effect detection, high-frequency operation is sensitive beyond the electrical double layer and can probe entities at a range of micrometers in electrolytes with high ionic strength such as water at physiological salt concentrations. Far from being limited to single- or few-channel recordings like conventional electrochemical impedance spectroscopy, the massively parallel design of the array permits electrically imaging micrometer-scale entities with each electrode serving as a separate pixel. This allows observation of complex kinetics in heterogeneous environments, for example, the motion of living cells on the surface of the array. This imaging aspect is further strengthened by the ability to distinguish between analyte species based on the sign and magnitude of their AC response. Finally, we show here that sensitivity down to the attofarad level combined with the small electrode size permits detection of individual 28 nm diameter particles as they land on the sensor surface. Interestingly, using finite-element methods, it is also possible to calculate accurately the full three-dimensional electric field and current distributions during operation at the level of the

  6. Feasibility of High Frequency Acoustic Imaging for Inspection of Containments

    SciTech Connect

    C.N. Corrado; J.E. Bondaryk; V. Godino

    1998-08-01

    The Nuclear Regulatory Commission has a program at the Oak Ridge National Laboratory to provide assistance in their assessment of the effects of potential degradation on the structural integrity and Ieaktightness of metal containment vessels and steel liners of concrete containment in nuclear power plants. One of the program objectives is to identify a technique(s) for inspection of inaccessible portions of the containment pressure boundary. Acoustic imaging has been identified as one of these potential techniques. A numerical feasibility study investigated the use of high-frequency bistatic acoustic imaging techniques for inspection of inaccessible portions of the metallic pressure boundary of nuclear power plant containment. The range-dependent version of the OASES Code developed at the Massachusetts Institute of Technology was utilized to perform a series of numerical simulations. OASES is a well developed and extensively tested code for evaluation of the acoustic field in a system of stratified fluid and/or elastic layers. Using the code, an arbitrary number of fluid or solid elastic layers are interleaved, with the outer layers modeled as halfspaces. High frequency vibrational sources were modeled to simulate elastic waves in the steel. The received field due to an arbitrary source array can be calculated at arbitrary depth and range positions. In this numerical study, waves that reflect and scatter from surface roughness caused by modeled degradations (e.g., corrosion) are detected and used to identify and map the steel degradation. Variables in the numerical study included frequency, flaw size, interrogation distance, and sensor incident angle.Based on these analytical simulations, it is considered unlikely that acoustic imaging technology can be used to investigate embedded steel liners of reinforced concrete containment. The thin steel liner and high signal losses to the concrete make this application difficult. Results for portions of steel containment

  7. High-frequency phenomena in magnetic recording and inductive devices

    NASA Astrophysics Data System (ADS)

    Jury, Jason Charles

    At high frequencies (>1 GHz), ferromagnetic materials and associated electronic circuitry show interesting and sometimes undesirable behavior. In this dissertation, we examine high-frequency effects in magnetic recording and magnetic inductive devices. We analyze "impedance profiling" of the disk drive interconnect, as a way of shaping the write current waveform. This proves to be useful under somewhat limited conditions (for write head with low impedance, characteristic time of the shaped waveform less than the one-way interconnect propagation delay). We then analyze a buffer amplifier (consisting of a single transistor in an emitter-follower configuration) as a means of improving the electronic signal to noise ratio (SNR) associated with high-resistance read sensors. We develop and utilize a "matched filter bound" SNR for assessing the performance of the disk drive read-path. For a hypothetical recording system at an areal density of 1 terabit/in2, the buffer amplifier improves SNR anywhere from 0.5 dB for 670 Mb/s up to 1 dB for 4.17 Gb/s. We then present measurements and quantitative analysis for magnetic fluctuation noise in read sensors. The analysis is enabled by rigorous calibration of the noise measurement setup. We are able to explain the behavior of the mag-noise (primary) resonance frequency versus bias current and externally-applied field, by using a micromagnetic model (NIST-OOMMF) where we also account for sensor heating and associated reduction in free-layer and biasing magnet saturation moment. We then analyze the behavior of multi-domain magnetic materials and the associated inductive device behaviors. First we utilize micromagnetic modeling to calculate the spin-resonance modes associated with multi-domain films. We find agreement in trend between the modeling results and experimentally-observed sub-FMR permeability resonances, particularly that both model and experiment predict a power-law dependence of frequency on the ratio of thickness to

  8. Novel high frequency devices with graphene and GaN

    NASA Astrophysics Data System (ADS)

    Zhao, Pei

    This work focuses on exploring new materials and new device structures to develop novel devices that can operate at very high speed. In chapter 2, the high frequency performance limitations of graphene transistor with channel length less than 100 nm are explored. The simulated results predict that intrinsic cutoff frequency fT of graphene transistor can be close to 2 THz at 15 nm channel length. In chapter 3, we explored the possibility of developing a 2D materials based vertical tunneling device. An analytical model to calculate the channel potentials and current-voltage characteristics in a Symmetric tunneling Field-Effect-Transistor (SymFET) is presented. The symmetric resonant peak in SymFET is a good candidate for high-speed analog applications. Rest of the work focuses on Gallium Nitride (GaN), several novel device concepts based on GaN heterostructure have been proposed for high frequency and high power applications. In chapter 4, we compared the performance of GaN Schottky diodes on bulk GaN substrates and GaN-on-sapphire substrates. In addition, we also discussed the lateral GaN Schottky diode between metal/2DEGs. The advantage of lateral GaN Schottky diodes is the intrinsic cutoff frequency is in the THz range. In chapter 5, a GaN Heterostructure barrier diode (HBD) is designed using the polarization charge and band offset at the AlGaN/GaN heterojunction. The polarization charge at AlGaN/GaN interface behaves as a delta-doping which induces a barrier without any chemical doping. The IV characteristics can be explained by the barrier controlled thermionic emission current. GaN HBDs can be directly integrated with GaN HEMTs, and serve as frequency multipliers or mixers for RF applications. In chapter 6, a GaN based negative effective mass oscillator (NEMO) is proposed. The current in NEMO is estimated under the ballistic limits. Negative differential resistances (NDRs) can be observed with more than 50% of the injected electrons occupied the negative

  9. Inelastic frontier: Discovering dark matter at high recoil energy

    DOE PAGES

    Bramante, Joseph; Fox, Patrick J.; Kribs, Graham D.; ...

    2016-12-27

    There exist well-motivated models of particle dark matter which predominantly scatter inelastically off nuclei in direct detection experiments. This inelastic transition causes the dark matter to upscatter in terrestrial experiments into an excited state up to 550 keV heavier than the dark matter itself. An inelastic transition of this size is highly suppressed by both kinematics and nuclear form factors. In this paper, we extend previous studies of inelastic dark matter to determine the present bounds on the scattering cross section and the prospects for improvements in sensitivity. Three scenarios provide illustrative examples: nearly pure Higgsino supersymmetric dark matter, magnetic inelasticmore » dark matter, and inelastic models with dark photon exchange. We determine the elastic scattering rate (through loop diagrams involving the heavy state) as well as verify that exothermic transitions are negligible (in the parameter space we consider). Presently, the strongest bounds on the cross section are from xenon at LUX-PandaX (when the mass splitting δ≲160 keV), iodine at PICO (when 160≲δ≲300 keV), and tungsten at CRESST (when δ≳300 keV). Amusingly, once δ≳200 keV, weak scale (and larger) dark matter–nucleon scattering cross sections are allowed. The relative competitiveness of these diverse experiments is governed by the upper bound on the recoil energies employed by each experiment, as well as strong sensitivity to the mass of the heaviest element in the detector. Several implications, including sizable recoil energy-dependent annual modulation and improvements for future experiments, are discussed. We show that the xenon experiments can improve on the PICO results, if they were to analyze their existing data over a larger range of recoil energies, i.e., 20–500 keV Intriguingly, CRESST has reported several events in the recoil energy range 45–100 keV that, if interpreted as dark matter scattering, is compatible with δ~200 keV and an

  10. A study of nuclear recoil backgrounds in dark matter detectors

    NASA Astrophysics Data System (ADS)

    Westerdale, Shawn S.

    Despite the great success of the Standard Model of particle physics, a preponderance of astrophysical evidence suggests that it cannot explain most of the matter in the universe. This so-called dark matter has eluded direct detection, though many theoretical extensions to the Standard Model predict the existence of particles with a mass on the 1-1000 GeV scale that interact only via the weak nuclear force. Particles in this class are referred to as Weakly Interacting Massive Particles (WIMPs), and their high masses and low scattering cross sections make them viable dark matter candidates. The rarity of WIMP-nucleus interactions makes them challenging to detect: any background can mask the signal they produce. Background rejection is therefore a major problem in dark matter detection. Many experiments greatly reduce their backgrounds by employing techniques to reject electron recoils. However, nuclear recoil backgrounds, which produce signals similar to what we expect from WIMPs, remain problematic. There are two primary sources of such backgrounds: surface backgrounds and neutron recoils. Surface backgrounds result from radioactivity on the inner surfaces of the detector sending recoiling nuclei into the detector. These backgrounds can be removed with fiducial cuts, at some cost to the experiment's exposure. In this dissertation we briefly discuss a novel technique for rejecting these events based on signals they make in the wavelength shifter coating on the inner surfaces of some detectors. Neutron recoils result from neutrons scattering off of nuclei in the detector. These backgrounds may produce a signal identical to what we expect from WIMPs and are extensively discussed here. We additionally present a new tool for calculating (alpha, n) yields in various materials. We introduce the concept of a neutron veto system designed to shield against, measure, and provide an anti-coincidence veto signal for background neutrons. We discuss the research and development

  11. Inelastic frontier: Discovering dark matter at high recoil energy

    NASA Astrophysics Data System (ADS)

    Bramante, Joseph; Fox, Patrick J.; Kribs, Graham D.; Martin, Adam

    2016-12-01

    There exist well-motivated models of particle dark matter which predominantly scatter inelastically off nuclei in direct detection experiments. This inelastic transition causes the dark matter to upscatter in terrestrial experiments into an excited state up to 550 keV heavier than the dark matter itself. An inelastic transition of this size is highly suppressed by both kinematics and nuclear form factors. In this paper, we extend previous studies of inelastic dark matter to determine the present bounds on the scattering cross section and the prospects for improvements in sensitivity. Three scenarios provide illustrative examples: nearly pure Higgsino supersymmetric dark matter, magnetic inelastic dark matter, and inelastic models with dark photon exchange. We determine the elastic scattering rate (through loop diagrams involving the heavy state) as well as verify that exothermic transitions are negligible (in the parameter space we consider). Presently, the strongest bounds on the cross section are from xenon at LUX-PandaX (when the mass splitting δ ≲160 keV ), iodine at PICO (when 160 ≲δ ≲300 keV ), and tungsten at CRESST (when δ ≳300 keV ). Amusingly, once δ ≳200 keV , weak scale (and larger) dark matter-nucleon scattering cross sections are allowed. The relative competitiveness of these diverse experiments is governed by the upper bound on the recoil energies employed by each experiment, as well as strong sensitivity to the mass of the heaviest element in the detector. Several implications, including sizable recoil energy-dependent annual modulation and improvements for future experiments, are discussed. We show that the xenon experiments can improve on the PICO results, if they were to analyze their existing data over a larger range of recoil energies, i.e., 20-500 keV Intriguingly, CRESST has reported several events in the recoil energy range 45-100 keV that, if interpreted as dark matter scattering, is compatible with δ ˜200 keV and an

  12. A Study of Nuclear Recoil Backgrounds in Dark Matter Detectors

    SciTech Connect

    Westerdale, Shawn S.

    2016-01-01

    Despite the great success of the Standard Model of particle physics, a preponderance of astrophysical evidence suggests that it cannot explain most of the matter in the universe. This so-called dark matter has eluded direct detection, though many theoretical extensions to the Standard Model predict the existence of particles with a mass on the $1-1000$ GeV scale that interact only via the weak nuclear force. Particles in this class are referred to as Weakly Interacting Massive Particles (WIMPs), and their high masses and low scattering cross sections make them viable dark matter candidates. The rarity of WIMP-nucleus interactions makes them challenging to detect: any background can mask the signal they produce. Background rejection is therefore a major problem in dark matter detection. Many experiments greatly reduce their backgrounds by employing techniques to reject electron recoils. However, nuclear recoil backgrounds, which produce signals similar to what we expect from WIMPs, remain problematic. There are two primary sources of such backgrounds: surface backgrounds and neutron recoils. Surface backgrounds result from radioactivity on the inner surfaces of the detector sending recoiling nuclei into the detector. These backgrounds can be removed with fiducial cuts, at some cost to the experiment's exposure. In this dissertation we briefly discuss a novel technique for rejecting these events based on signals they make in the wavelength shifter coating on the inner surfaces of some detectors. Neutron recoils result from neutrons scattering from nuclei in the detector. These backgrounds may produce a signal identical to what we expect from WIMPs and are extensively discussed here. We additionally present a new tool for calculating ($\\alpha$, n)yields in various materials. We introduce the concept of a neutron veto system designed to shield against, measure, and provide an anti-coincidence veto signal for background neutrons. We discuss the research and development

  13. Inelastic frontier: Discovering dark matter at high recoil energy

    SciTech Connect

    Bramante, Joseph; Fox, Patrick J.; Kribs, Graham D.; Martin, Adam

    2016-12-27

    There exist well-motivated models of particle dark matter which predominantly scatter inelastically off nuclei in direct detection experiments. This inelastic transition causes the dark matter to upscatter in terrestrial experiments into an excited state up to 550 keV heavier than the dark matter itself. An inelastic transition of this size is highly suppressed by both kinematics and nuclear form factors. In this paper, we extend previous studies of inelastic dark matter to determine the present bounds on the scattering cross section and the prospects for improvements in sensitivity. Three scenarios provide illustrative examples: nearly pure Higgsino supersymmetric dark matter, magnetic inelastic dark matter, and inelastic models with dark photon exchange. We determine the elastic scattering rate (through loop diagrams involving the heavy state) as well as verify that exothermic transitions are negligible (in the parameter space we consider). Presently, the strongest bounds on the cross section are from xenon at LUX-PandaX (when the mass splitting δ≲160 keV), iodine at PICO (when 160≲δ≲300 keV), and tungsten at CRESST (when δ≳300 keV). Amusingly, once δ≳200 keV, weak scale (and larger) dark matter–nucleon scattering cross sections are allowed. The relative competitiveness of these diverse experiments is governed by the upper bound on the recoil energies employed by each experiment, as well as strong sensitivity to the mass of the heaviest element in the detector. Several implications, including sizable recoil energy-dependent annual modulation and improvements for future experiments, are discussed. We show that the xenon experiments can improve on the PICO results, if they were to analyze their existing data over a larger range of recoil energies, i.e., 20–500 keV Intriguingly, CRESST has reported several events in the recoil energy range 45–100 keV that, if interpreted as dark matter scattering, is compatible with δ~200 keV and an

  14. Sub-recoil laser cooling of metastable helium

    NASA Astrophysics Data System (ADS)

    Liu, Liang

    2000-08-01

    This work presents the results of several experiments in sub-recoil laser cooling of metastable Helium (He*) on the 23S1 --> 23P0,1,2 transitions at λ = 1.083 μm and on the 23S1 --> 33P0,1,2 transitions at λ = 389 nm in a magnetic field. The idea is to combine the principle of sub-recoil cooling based on VSCPT (Velocity Selective Coherent Population Trapping) with the VSR (Velocity Selective Resonance) produced by an applied magnetic field. We first review the works on Doppler and sub-Doppler cooling, and point out that the sub-recoil cooling is possible when the atom is dark to the laser field. When the kinetic energy term is considered in the Hamiltonian, the dark state has a distribution over detuning and laser intensity. Thus for limited interaction time for blue detuning, the trapped state leads a single sub-recoil peak, and for red detuning, it leads a single sub-recoil dip. W present a semiclassical description of VSCPT in a magnetic field. In this description, two terms are added to the Hamiltonian simultaneously, that is the kinetic energy term and Zeeman shift term. With the kinetic energy term, the dependence of the dark state on laser parameters can be understood, and with the Zeeman term, VSCPT phenomena can be controlled by the applied magnetic field. We present an experiment on the He* J = 1 --> 1 transition driven by σ+ - σ- counter-propagating fields in a magnetic field parallel to the k-vector of the lasers, which produces a standard A system. We first apply a magnetic field parallel to the k-vector of laser beams, and observe the change of VSCPT vs the magnetic field. Then we study VSCPT behaviour in zero magnetic field for different detuning, intensity and interaction time. The configuration is then changed to a σ+ standing wave in a magnetic field perpendicular to the k-vector of the laser beams. For the J = 1 --> 0 transition, besides the dark state similar to 1 --> 1 transition, there is a leak from J = 0, mJ = 0 of the excited state

  15. Shooter-System Performance Variability as a Function of Recoil Dynamics.

    PubMed

    Morelli, Frank; Neugebauer, Jennifer M; Haynes, Courtney A; Fry, Thomas C; Ortega, Samson V; Struve, Douglas J; LaFiandra, Michael E; Larkin, Gabriella B

    2017-09-01

    The goal of this study was to quantify shooter performance relative to subtle variations in recoil energy. Marksmanship performance remains undefined for subtle distinctions in weapon recoil energy across common small-arms platforms. Weapons were customized using multiple components and ammunition types. Firing scenarios were designed to examine the effect of recoil energy on shooter timing and accuracy. The results suggest that recoil condition does not affect timing during firing sequences designed to elicit differences in timed-fire performance. Recoil condition did, however, influence shot placement, with accuracy decreasing as the energy associated with firing increased. Subjective recoil estimations were quantified according to relative magnitude and spatial distribution of perceived energy transferred at shooter-weapon surface contact locations. The absence of differences in time to engage may be reflective of resistance to recoil-induced point-of-aim deviation based on experience. Distinctions in performance were revealed despite subtle differences in recoil energy between conditions. An instrument that may be sensitive to shooter perception of subtle differences in recoil energy during firing was also developed. The findings inform performance expectations for small-arms systems relative to recoil energy levels transferred to the shooter during dynamic firing events.

  16. LONGITUDINAL DYNAMICS IN HIGH FREQUENCY FFAG RECIRCULATING ACCELERATORS.

    SciTech Connect

    BERG,J.S.

    2002-04-08

    A recirculating accelerator accelerates the beam by passing through accelerating cavities multiple times. An FFAG recirculating accelerator uses a single arc to connect the linacs together, as opposed to multiple arcs for the different energies. For most scenarios using high-frequency RF, it is impractical to change the phase of the RF on each pass, at least for lower energy accelerators. Ideally, therefore, the WAG arc will be isochronous, so that the particles come back to the same phase (on-crest) on each linac pass. However, it is not possible to make the FFAG arcs isochronous (compared to the RF period) over a large energy range. This paper demonstrates that one can nonetheless make an WAG recirculating accelerator work. Given the arc's path length as a function of energy and the number of turns to accelerate for, one can find the minimum voltage (and corresponding initial conditions) required to accelerate a reference particle to the desired energy. I also briefly examine how the longitudinal acceptance varies with the number of turns that one accelerates.

  17. High Frequency Ultrasound Array Designed for Ultrasound Guided Breast Biopsy

    PubMed Central

    Cummins, Thomas; Eliahoo, Payam; Shung, K. Kirk

    2016-01-01

    This paper describes the development of a miniaturized high frequency linear array that can be integrated within a core biopsy needle to improve tissue sampling accuracy during breast cancer biopsy procedures. The 64 element linear array has an element width of 14 μm, kerf width of 6 μm, element length of 1 mm and element thickness of 24 μm. The 2–2 array composite was fabricated using deep reactive ion etching of PMN-PT single crystal material. The array composite fabrication process as well as a novel high density electrical interconnect solution are presented and discussed. Array performance measurements show that the array had a center frequency and fractional bandwidth (−6 dB) of 59.1 MHz and 29.4%, respectively. Insertion loss and adjacent element cross talk at the center frequency were −41.0 dB and −23.7 dB, respectively. A B-mode image of a tungsten wire target phantom was captured using a synthetic aperture imaging system and the imaging test results demonstrate axial and lateral resolutions of 33.2 μm and 115.6 um, respectively. PMID:27046895

  18. Turbofan Noise Propagation and Radiation at High Frequencies

    NASA Technical Reports Server (NTRS)

    Koch, Danielle (Technical Monitor); Eversman, Walter

    2003-01-01

    This report summarizes progress on NASA Glenn Research Center Grant NAG3-2718 to the University of Missouri at Rolla This grant was awarded on February 22, 2002 and this report covers the performance period to September 30, 2002. There is considerable overlap in research effort with previous NASA Glenn Grant NAG3-2340, as the current effort represents a continuation and extension of this previous grant, which with a no cost supplement terminated on January 31, 2002. This report outlines progress on each task in the original proposal. In addition to progress on several of the specifically proposed tasks, considerable progress has been made in FEM algorithm development with the intent of introducing computational efficiencies required to model high frequency propagation and radiation and to open the possibility of expanding the scope of the modeling capability to three dimensional duct and nacelle geometries. Appended to this document is a paper presented at the 8th AIAA/CEAS Aeroacoustics Conference in June 2002. This paper overlaps the present grant and the previous grant identified above, and it is noted that this paper has also been appended to the final report for NAG3-2304.

  19. Why high-frequency pulse tubes can be tipped

    SciTech Connect

    Swift, Gregory W092710; Backhaus, Scott N

    2010-01-01

    The typical low-frequency pulse-tube refrigerator loses significant cooling power when it is tipped with the pulse tube's cold end above its hot end, because natural convection in the pulse tube loads the cold heat exchanger. Yet most high-frequency pulse-tube refrigerators work well in any orientation with respect to gravity. In such a refrigerator, natural convection is suppressed by sufficiently fast velocity oscil1ations, via a nonlinear hydrodynamic effect that tends to align the density gradients in the pulse tube parallel to the oscillation direction. Since gravity's tendency to cause convection is only linear in the pulse tube's end-to-end temperature difference while the oscillation's tendency to align density gradients with oscillating velocity is nonlinear, it is easiest to suppress convection when the end-to-end temperature difference is largest. Simple experiments demonstrate this temperature dependence, the strong dependence on the oscillating velocity, and little dependence on the magnitude or phase of the oscillating pressure. In some circumstances in this apparatus, the suppression of convection is a hysteretic function of oscillating velocity. In some other circumstances, a time-dependent convective state seems more difficult to suppress.

  20. Software for Displaying High-Frequency Test Data

    NASA Technical Reports Server (NTRS)

    Elmore, Jason L.

    2003-01-01

    An easy-to-use, intuitive computer program was written to satisfy a need of test operators and data requestors to quickly view and manipulate high-frequency test data recorded at the East and West Test Areas at Marshall Space Flight Center. By enabling rapid analysis, this program makes it possible to reduce times between test runs, thereby potentially reducing the overall cost of test operations. The program can be used to perform quick frequency analysis, using multiple fast- Fourier-transform windowing and amplitude options. The program can generate amplitude-versus-time plots with full zoom capabilities, frequency-component plots at specified time intervals, and waterfall plots (plots of spectral intensity versus frequency at successive small time intervals, showing the changing frequency components over time). There are options for printing of the plots and saving plot data as text files that can be imported into other application programs. The program can perform all of the aforementioned plotting and plot-data-handling functions on a relatively inexpensive computer; other software that performs the same functions requires computers with large amounts of power and memory.

  1. Bottomside Ionospheric Electron Density Specification using Passive High Frequency Signals

    NASA Astrophysics Data System (ADS)

    Kaeppler, S. R.; Cosgrove, R. B.; Mackay, C.; Varney, R. H.; Kendall, E. A.; Nicolls, M. J.

    2016-12-01

    The vertical bottomside electron density profile is influenced by a variety of natural sources, most especially traveling ionospheric disturbances (TIDs). These disturbances cause plasma to be moved up or down along the local geomagnetic field and can strongly impact the propagation of high frequency radio waves. While the basic physics of these perturbations has been well studied, practical bottomside models are not well developed. We present initial results from an assimilative bottomside ionosphere model. This model uses empirical orthogonal functions based on the International Reference Ionosphere (IRI) to develop a vertical electron density profile, and features a builtin HF ray tracing function. This parameterized model is then perturbed to model electron density perturbations associated with TIDs or ionospheric gradients. Using the ray tracing feature, the model assimilates angle of arrival measurements from passive HF transmitters. We demonstrate the effectiveness of the model using angle of arrival data. Modeling results of bottomside electron density specification are compared against suitable ancillary observations to quantify accuracy of our model.

  2. High frequency dynamic engine simulation. [TF-30 engine

    NASA Technical Reports Server (NTRS)

    Schuerman, J. A.; Fischer, K. E.; Mclaughlin, P. W.

    1977-01-01

    A digital computer simulation of a mixed flow, twin spool turbofan engine was assembled to evaluate and improve the dynamic characteristics of the engine simulation to disturbance frequencies of at least 100 Hz. One dimensional forms of the dynamic mass, momentum and energy equations were used to model the engine. A TF30 engine was simulated so that dynamic characteristics could be evaluated against results obtained from testing of the TF30 engine at the NASA Lewis Research Center. Dynamic characteristics of the engine simulation were improved by modifying the compression system model. Modifications to the compression system model were established by investigating the influence of size and number of finite dynamic elements. Based on the results of this program, high frequency engine simulations using finite dynamic elements can be assembled so that the engine dynamic configuration is optimum with respect to dynamic characteristics and computer execution time. Resizing of the compression systems finite elements improved the dynamic characteristics of the engine simulation but showed that additional refinements are required to obtain close agreement simulation and actual engine dynamic characteristics.

  3. HIGH FREQUENCY POWER TRANSMISSION LINE FOR CYCLOTRONS AND THE LIKE

    DOEpatents

    Armstrong, W.J.

    1954-04-20

    High-frequency power transmission systems, particularly a stacked capacitance alternating power current transmission line wherein maximum utilization of the effective conductios skin of the line conductors is achieved while enabling a low impedance to be obtained are reported. The transmission line consists of a number of flat metal strips with interleaved dielectric strips. The metal dielectric strips are coiled spirally with the axis of the spiral extending along the length of the strips, and the alternating metal strips at the output end have outwardly extending aligned lugs which are directly strapped together and connected to the respective terminals on the load. At the input end of the transmission line, similarly, the alternate metal strips are directly strapped together and connected to an altereating current source. With the arrangement described each metal strip conducts on both sides, so that the metal strips are designed to have a thickness corresponding to twice the depth of the "skin effect" conducting lamina of each conductor at the source frequency.

  4. High-frequency stimulation of excitable cells and networks.

    PubMed

    Weinberg, Seth H

    2013-01-01

    High-frequency (HF) stimulation has been shown to block conduction in excitable cells including neurons and cardiac myocytes. However, the precise mechanisms underlying conduction block are unclear. Using a multi-scale method, the influence of HF stimulation is investigated in the simplified FitzhHugh-Nagumo and biophysically-detailed Hodgkin-Huxley models. In both models, HF stimulation alters the amplitude and frequency of repetitive firing in response to a constant applied current and increases the threshold to evoke a single action potential in response to a brief applied current pulse. Further, the excitable cells cannot evoke a single action potential or fire repetitively above critical values for the HF stimulation amplitude. Analytical expressions for the critical values and thresholds are determined in the FitzHugh-Nagumo model. In the Hodgkin-Huxley model, it is shown that HF stimulation alters the dynamics of ionic current gating, shifting the steady-state activation, inactivation, and time constant curves, suggesting several possible mechanisms for conduction block. Finally, we demonstrate that HF stimulation of a network of neurons reduces the electrical activity firing rate, increases network synchronization, and for a sufficiently large HF stimulation, leads to complete electrical quiescence. In this study, we demonstrate a novel approach to investigate HF stimulation in biophysically-detailed ionic models of excitable cells, demonstrate possible mechanisms for HF stimulation conduction block in neurons, and provide insight into the influence of HF stimulation on neural networks.

  5. High-Frequency Gravitational Wave Induced Nuclear Fusion

    SciTech Connect

    Fontana, Giorgio; Baker, Robert M. L. Jr.

    2007-01-30

    Nuclear fusion is a process in which nuclei, having a total initial mass, combine to produce a single nucleus, having a final mass less than the total initial mass. Below a given atomic number the process is exothermic; that is, since the final mass is less than the combined initial mass and the mass deficit is converted into energy by the nuclear fusion. On Earth nuclear fusion does not happen spontaneously because electrostatic barriers prevent the phenomenon. To induce controlled, industrial scale, nuclear fusion, only a few methods have been discovered that look promising, but net positive energy production is not yet possible because of low overall efficiency of the systems. In this paper we propose that an intense burst of High Frequency Gravitational Waves (HFGWs) could be focused or beamed to a target mass composed of appropriate fuel or target material to efficiently rearrange the atomic or nuclear structure of the target material with consequent nuclear fusion. Provided that efficient generation of HFGW can be technically achieved, the proposed fusion reactor could become a viable solution for the energy needs of mankind and alternatively a process for beaming energy to produce a source of fusion energy remotely - even inside solid materials.

  6. Low temperature high frequency coaxial pulse tube for space application

    SciTech Connect

    Charrier, Aurelia; Charles, Ivan; Rousset, Bernard; Duval, Jean-Marc

    2014-01-29

    The 4K stage is a critical step for space missions. The Hershel mission is using a helium bath, which is consumed day by day (after depletion, the space mission is over) while the Plank mission is equipped with one He4 Joule-Thomson cooler. Cryogenic chain without helium bath is a challenge for space missions and 4.2K Pulse-Tube working at high frequency (around 30Hz) is one option to take it up. A low temperature Pulse-Tube would be suitable for the ESA space mission EChO (Exoplanet Characterisation Observatory, expected launch in 2022), which requires around 30mW cooling power at 6K; and for the ESA space mission ATHENA (Advanced Telescope for High ENergy Astrophysics), to pre-cool the sub-kelvin cooler (few hundreds of mW at 15K). The test bench described in this paper combines a Gifford-McMahon with a coaxial Pulse-Tube. A thermal link is joining the intercept of the Pulse-Tube and the second stage of the Gifford-McMahon. This intercept is a separator between the hot and the cold regenerators of the Pulse-Tube. The work has been focused on the cold part of this cold finger. Coupled with an active phase shifter, this Pulse-Tube has been tested and optimized and temperatures as low as 6K have been obtained at 30Hz with an intercept temperature at 20K.

  7. Microfluidic particle manipulation using high frequency surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Ai, Ye; Collins, David J.

    2016-11-01

    Precise manipulation of particles and biological cells remains a very active research area in microfluidics. Among various force fields applied for microfluidic manipulations, acoustic waves have superior propagating properties in solids and fluids, which can readily enable non-contact cell manipulation in long operating distances. Exploiting acoustic waves for fluid and cell manipulation in microfluidics has led to a newly emerging research area, acoustofluidics. In this work, I will present particle and cell manipulation in microfluidics using high frequency surface acoustic waves (SAW). In particular, I will discuss a unique design of a focused IDT (FIDT) structure, which is able to generate a highly localized SAW field on the order of 20 µm wide. This highly focused acoustic beam has an effective manipulation area size that is comparable to individual micron-sized particles. Here, I demonstrate the use of this highly localized SAW field for single particle level sorting with sub-millisecond pulses and selective capture of particles. Based on the presented studies on acoustic particle manipulation, I envision that the merging of acoustics and microfluidics could enable various particle and cell manipulations needed in microfluidic applications. We acknowledge the support received from Singapore University of Technology and Design (SUTD)-Massachusetts Institute of Technology (MIT) International Design Center (IDG11300101) and SUTD Startup Research Grant (SREP13053) awarded to Y.A.

  8. Refraction of high frequency noise in an arbitrary jet flow

    NASA Technical Reports Server (NTRS)

    Khavaran, Abbas; Krejsa, Eugene A.

    1994-01-01

    Refraction of high frequency noise by mean flow gradients in a jet is studied using the ray-tracing methods of geometrical acoustics. Both the two-dimensional (2D) and three-dimensional (3D) formulations are considered. In the former case, the mean flow is assumed parallel and the governing propagation equations are described by a system of four first order ordinary differential equations. The 3D formulation, on the other hand, accounts for the jet spreading as well as the axial flow development. In this case, a system of six first order differential equations are solved to trace a ray from its source location to an observer in the far field. For subsonic jets with a small spreading angle both methods lead to similar results outside the zone of silence. However, with increasing jet speed the two prediction models diverge to the point where the parallel flow assumption is no longer justified. The Doppler factor of supersonic jets as influenced by the refraction effects is discussed and compared with the conventional modified Doppler factor.

  9. High to very high frequency metal/anomaly detector

    NASA Astrophysics Data System (ADS)

    Heinz, Daniel C.; Brennan, Michael L.; Steer, Michael B.; Melber, Adam W.; Cua, John T.

    2014-05-01

    Typical metal detectors work at very low to low frequencies. In this paper, a metal/anomaly detector design that operates in the high to very high frequency range is presented. This design uses a high-Q tuned loop antenna for metal/anomaly detection. By measuring the return loss or voltage standing wave ratio a frequency notch can be detected. Tuning to the optimal location of the notch can be accomplished by monitoring the phase response. This phase monitoring technique can be used to ground balance the detector. As a metal object is moved along the longitudinal axis of the loop antenna a substantial shift in the frequency of the notch is detected. For metal targets, the frequency shift is positive, and for ferrite and other targets, the frequency shift is negative. This frequency shift is created by the proximity of the target causing a change in the impedance of the antenna. Experiments with a prototype antenna show long-range detection with low power requirements. The detector requires only one loop with one winding which is used for both transmit and receive. This allows for a metal/anomaly detector with a very simple design. The design is lightweight and, depending on loop size, significantly increases detection depth performance. In the full paper, modeling and further experimental results will be presented. Performance results for various types of soil and for different types of targets are presented.

  10. High-frequency modes of a magnetic antivortex

    NASA Astrophysics Data System (ADS)

    Asmat-Uceda, Martin; Riley, Grant; Haldar, Arabinda; Buchanan, Kristen

    2015-03-01

    Magnetic vortices have attracted considerable attention in recent years not only because of their interesting physical properties but also due to their potential for applications. The magnetic antivortex (AV), the topological counterpart of the magnetic vortex, possesses similarly rich dynamics and its spin configuration may prove advantageous for spin-wave-based devices, however, it has not been studied as intensely. Recent experiments show that AV's will form naturally at the intersections of patterned pound-key-like nanostructures that are magnetically soft. Here we present micromagnetic simulations of the dynamics of AV's in these structures. The simulations show that pound-key-like structures made of 30-nm thick Permalloy exhibit a complex dynamic profile that includes a number of discrete high-frequency modes (>1 GHz). Spatial maps of the dynamic modes that were constructed using Fourier analysis of the simulation results show modes that are in similar in character to the radial and azimuthal modes observed for magnetic vortices but the spin dynamics also differ from those of a vortex due to the presence of the elongated nanowires in the pound-key-like structure. The frequencies of the observed modes tend to decrease with increasing sample size, however, the general features of the modes remains relatively unaffected by the structure size. The simulations will be compared to Brillouin Light Scattering (BLS) experimental results. This work was supported by the US DOE-BES Award #ER 46854.

  11. High frequency guided wave propagation in monocrystalline silicon wafers

    NASA Astrophysics Data System (ADS)

    Pizzolato, Marco; Masserey, Bernard; Robyr, Jean-Luc; Fromme, Paul

    2017-04-01

    Monocrystalline silicon wafers are widely used in the photovoltaic industry for solar panels with high conversion efficiency. The cutting process can introduce micro-cracks in the thin wafers and lead to varying thickness. High frequency guided ultrasonic waves are considered for the structural monitoring of the wafers. The anisotropy of the monocrystalline silicon leads to variations of the wave characteristics, depending on the propagation direction relative to the crystal orientation. Full three-dimensional Finite Element simulations of the guided wave propagation were conducted to visualize and quantify these effects for a line source. The phase velocity (slowness) and skew angle of the two fundamental Lamb wave modes (first anti-symmetric mode A0 and first symmetric mode S0) for varying propagation directions relative to the crystal orientation were measured experimentally. Selective mode excitation was achieved using a contact piezoelectric transducer with a custom-made wedge and holder to achieve a controlled contact pressure. The out-of-plane component of the guided wave propagation was measured using a noncontact laser interferometer. Good agreement was found with the simulation results and theoretical predictions based on nominal material properties of the silicon wafer.

  12. Planck early results. VI. The High Frequency Instrument data processing

    NASA Astrophysics Data System (ADS)

    Planck HFI Core Team; Ade, P. A. R.; Aghanim, N.; Ansari, R.; Arnaud, M.; Ashdown, M.; Aumont, J.; Banday, A. J.; Bartelmann, M.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Bernard, J.-P.; Bersanelli, M.; Bock, J. J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bradshaw, T.; Bucher, M.; Cardoso, J.-F.; Castex, G.; Catalano, A.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chen, X.; Chiang, C.; Church, S.; Clements, D. L.; Colley, J.-M.; Colombi, S.; Couchot, F.; Coulais, A.; Cressiot, C.; Crill, B. P.; Crook, M.; de Bernardis, P.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Dolag, K.; Dole, H.; Doré, O.; Douspis, M.; Dunkley, J.; Efstathiou, G.; Filliard, C.; Forni, O.; Fosalba, P.; Ganga, K.; Giard, M.; Girard, D.; Giraud-Héraud, Y.; Gispert, R.; Górski, K. M.; Gratton, S.; Griffin, M.; Guyot, G.; Haissinski, J.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Hildebrandt, S. R.; Hills, R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Huffenberger, K. M.; Jaffe, A. H.; Jones, W. C.; Kaplan, J.; Kneissl, R.; Knox, L.; Kunz, M.; Lagache, G.; Lamarre, J.-M.; Lange, A. E.; Lasenby, A.; Lavabre, A.; Lawrence, C. R.; Le Jeune, M.; Leroy, C.; Lesgourgues, J.; Macías-Pérez, J. F.; MacTavish, C. J.; Maffei, B.; Mandolesi, N.; Mann, R.; Marleau, F.; Marshall, D. J.; Masi, S.; Matsumura, T.; McAuley, I.; McGehee, P.; Melin, J.-B.; Mercier, C.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Mortlock, D.; Murphy, A.; Nati, F.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; North, C.; Noviello, F.; Novikov, D.; Osborne, S.; Pajot, F.; Patanchon, G.; Peacocke, T.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Piacentini, F.; Piat, M.; Plaszczynski, S.; Pointecouteau, E.; Ponthieu, N.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Reach, W. T.; Remazeilles, M.; Renault, C.; Riazuelo, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rusholme, B.; Saha, R.; Santos, D.; Savini, G.; Schaefer, B. M.; Shellard, P.; Spencer, L.; Starck, J.-L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Sygnet, J.-F.; Tauber, J. A.; Thum, C.; Torre, J.-P.; Touze, F.; Tristram, M.; van Leeuwen, F.; Vibert, L.; Vibert, D.; Wade, L. A.; Wandelt, B. D.; White, S. D. M.; Wiesemeyer, H.; Woodcraft, A.; Yurchenko, V.; Yvon, D.; Zacchei, A.

    2011-12-01

    We describe the processing of the 336 billion raw data samples from the High Frequency Instrument (HFI) which we performed to produce six temperature maps from the first 295 days of Planck-HFI survey data. These maps provide an accurate rendition of the sky emission at 100, 143, 217, 353, 545 and 857 GHz with an angular resolution ranging from 9.9 to 4.4'. The white noise level is around 1.5 μK degree or less in the 3 main CMB channels (100-217 GHz). The photometric accuracy is better than 2% at frequencies between 100 and 353 GHz and around 7% at the two highest frequencies. The maps created by the HFI Data Processing Centre reach our goals in terms of sensitivity, resolution, and photometric accuracy. They are already sufficiently accurate and well-characterised to allow scientific analyses which are presented in an accompanying series of early papers. At this stage, HFI data appears to be of high quality and we expect that with further refinements of the data processing we should be able to achieve, or exceed, the science goals of the Planck project. Corresponding author: F. R. Bouchet, e-mail: bouchet@iap.fr

  13. High frequency alternating current chip nano calorimeter with laser heating

    SciTech Connect

    Shoifet, E.; Schick, C.; Chua, Y. Z.; Huth, H.

    2013-07-15

    Heat capacity spectroscopy at frequencies up to 100 kHz is commonly performed by thermal effusivity measurements applying the 3ω-technique. Here we show that AC-calorimetry using a thin film chip sensor allows for the measurement of frequency dependent heat capacity in the thin film limit up to about 1 MHz. Using films thinner than the thermal length of the thermal wave (∼1 μm) at such frequencies is advantageous because it provides heat capacity alone and not in combination with other quantities like thermal conductivity, at least on a qualitative basis. The used calorimetric sensor and the sample are each less than 1 μm thick. For high frequency AC-calorimetry, high cooling rates at very small temperature differences are required. This is realized by minimizing the heated spot to the size of the on chip thermocouple (3 × 6 μm{sup 2}). A modulated laser beam shaped and positioned by a glass fiber is used as the heat source. The device was used to measure the complex heat capacity in the vicinity of the dynamic glass transition (structural relaxation) of poly(methyl methacrylate). Combining different calorimeters finally provides data between 10{sup −3} Hz and 10{sup 6} Hz. In this frequency range the dynamic glass transition shifts about 120 K.

  14. High frequency oscillations can pinpoint seizures progressing to status epilepticus

    PubMed Central

    Salami, Pariya; Lévesque, Maxime; Avoli, Massimo

    2016-01-01

    Status epilepticus (SE) is defined as a seizure lasting more than 5 min or a period of recurrent seizures without recovery between them. SE is a serious emergency condition that requires immediate intervention; therefore, identifying SE electrophysiological markers may translate in prompt care to stop it. Here, we analyzed the EEG signals recorded from the CA3 region of the hippocampus and the entorhinal cortex in rats that responded to systemic administration of 4-aminopyridine (4AP) by generating either isolated seizures or seizures progressing to SE. We found that high frequency oscillations (HFOs) – which can be categorized as ripples (80–200 Hz) and fast ripples (250–500 Hz) – had different patterns of occurrence in the two groups (n = 5 for each group). Specifically, fast ripples in CA3 and entorhinal cortex of the SE group occurred at higher rates than ripples, both during the ictal and post-ictal periods when compared to the HFOs recorded from the isolated seizure group. Our data reveal that different patterns of HFO occurrence can pinpoint seizures progressing to SE, thus suggesting the involvement of different neuronal networks at the termination of seizure discharges. PMID:27018321

  15. High Frequency Mechanical Pyroshock Simulations for Payload Systems

    SciTech Connect

    BATEMAN,VESTA I.; BROWN,FREDERICK A.; CAP,JEROME S.; NUSSER,MICHAEL A.

    1999-12-15

    Sandia National Laboratories (SNL) designs mechanical systems with components that must survive high frequency shock environments including pyrotechnic shock. These environments have not been simulated very well in the past at the payload system level because of weight limitations of traditional pyroshock mechanical simulations using resonant beams and plates. A new concept utilizing tuned resonators attached to the payload system and driven with the impact of an airgun projectile allow these simulations to be performed in the laboratory with high precision and repeatability without the use of explosives. A tuned resonator has been designed and constructed for a particular payload system. Comparison of laboratory responses with measurements made at the component locations during actual pyrotechnic events show excellent agreement for a bandwidth of DC to 4 kHz. The bases of comparison are shock spectra. This simple concept applies the mechanical pyroshock simulation simultaneously to all components with the correct boundary conditions in the payload system and is a considerable improvement over previous experimental techniques and simulations.

  16. High-Frequency Stimulation of Excitable Cells and Networks

    PubMed Central

    Weinberg, Seth H.

    2013-01-01

    High-frequency (HF) stimulation has been shown to block conduction in excitable cells including neurons and cardiac myocytes. However, the precise mechanisms underlying conduction block are unclear. Using a multi-scale method, the influence of HF stimulation is investigated in the simplified FitzhHugh-Nagumo and biophysically-detailed Hodgkin-Huxley models. In both models, HF stimulation alters the amplitude and frequency of repetitive firing in response to a constant applied current and increases the threshold to evoke a single action potential in response to a brief applied current pulse. Further, the excitable cells cannot evoke a single action potential or fire repetitively above critical values for the HF stimulation amplitude. Analytical expressions for the critical values and thresholds are determined in the FitzHugh-Nagumo model. In the Hodgkin-Huxley model, it is shown that HF stimulation alters the dynamics of ionic current gating, shifting the steady-state activation, inactivation, and time constant curves, suggesting several possible mechanisms for conduction block. Finally, we demonstrate that HF stimulation of a network of neurons reduces the electrical activity firing rate, increases network synchronization, and for a sufficiently large HF stimulation, leads to complete electrical quiescence. In this study, we demonstrate a novel approach to investigate HF stimulation in biophysically-detailed ionic models of excitable cells, demonstrate possible mechanisms for HF stimulation conduction block in neurons, and provide insight into the influence of HF stimulation on neural networks. PMID:24278435

  17. Carbon nanotube transistor based high-frequency electronics

    NASA Astrophysics Data System (ADS)

    Schroter, Michael

    At the nanoscale carbon nanotubes (CNTs) have higher carrier mobility and carrier velocity than most incumbent semiconductors. Thus CNT based field-effect transistors (FETs) are being considered as strong candidates for replacing existing MOSFETs in digital applications. In addition, the predicted high intrinsic transit frequency and the more recent finding of ways to achieve highly linear transfer characteristics have inspired investigations on analog high-frequency (HF) applications. High linearity is extremely valuable for an energy efficient usage of the frequency spectrum, particularly in mobile communications. Compared to digital applications, the much more relaxed constraints for CNT placement and lithography combined with already achieved operating frequencies of at least 10 GHz for fabricated devices make an early entry in the low GHz HF market more feasible than in large-scale digital circuits. Such a market entry would be extremely beneficial for funding the development of production CNTFET based process technology. This talk will provide an overview on the present status and feasibility of HF CNTFET technology will be given from an engineering point of view, including device modeling, experimental results, and existing roadblocks.

  18. Development and optimization of acoustic bubble structures at high frequencies.

    PubMed

    Lee, Judy; Ashokkumar, Muthupandian; Yasui, Kyuichi; Tuziuti, Toru; Kozuka, Teruyuki; Towata, Atsuya; Iida, Yasuo

    2011-01-01

    At high ultrasound frequencies, active bubble structures are difficult to capture due to the decrease in timescale per acoustic cycle and size of bubbles with increasing frequencies. However the current study demonstrates an association between the spatial distribution of visible bubbles and that of the active bubble structure established in the path of the propagating acoustic wave. By monitoring the occurrence of these visible bubbles, the development of active bubbles can be inferred for high frequencies. A series of still images depicting the formation of visible bubble structures suggest that a strong standing wave field exists at early stages of wave propagation and weakens by the increase in the attenuation of the acoustic wave, caused by the formation of large coalesced bubbles. This attenuation is clearly demonstrated by the occurrence of a force which causes bubbles to be driven toward the liquid surface and limit standing wave fields to near the surface. This force is explained in terms of the acoustic streaming and traveling wave force. It is found that a strong standing wave field is established at 168 kHz. At 448 kHz, large coalesced bubbles can significantly attenuate the acoustic pressure amplitude and weaken the standing wave field. When the frequency is increased to 726 kHz, acoustic streaming becomes significant and is the dominant force behind the disruption of the standing wave structure. The disruption of the standing wave structure can be minimized under certain pulse ON and OFF ratios.

  19. Fault-zone attenuation of high-frequency seismic waves

    NASA Astrophysics Data System (ADS)

    Blakeslee, Sam; Malin, Peter; Alvarez, Marcos

    1989-11-01

    We have developed a technique to measure seismic attenuation within an active fault-zone at seismogenic depths. Utilizing a pair of stations and pairs of earthquakes, spectral ratios are performed to isolate attenuation produced by wave-propagation within the fault-zone. This empirical approach eliminates common source, propagation, instrument and near-surface site effects. The technique was applied to a cluster of 19 earthquakes recorded by a pair of downhole instruments located within the San Andreas fault-zone, at Parkfield California. Over the 1-40 Hz bandwidth used in this analysis, amplitudes are found to decrease exponentially with frequency. Furthermore, the fault-zone propagation distance correlates with the severity of attenuation. Assuming a constant Q attenuation operator, the S-wave quality factor within the fault-zone at a depth of 5-6 kilometers is 31 (+7,-5). If fault-zones are low-Q environments, then near-source attenuation of high-frequency seismic waves may help to explain phenomenon such as fmax. Fault-zone Q may prove to be a valuable indicator of the mechanical behavior and rheology of fault-zones. Specific asperities can be monitored for precursory changes associated with the evolving stress-field within the fault-zone. The spatial and temporal resolution of the technique is fundamentally limited by the uncertainty in earthquake location and the interval time between earthquakes.

  20. Design, analysis, and testing of high frequency passively damped struts

    NASA Technical Reports Server (NTRS)

    Yiu, Y. C.; Davis, L. Porter; Napolitano, Kevin; Ninneman, R. Rory

    1993-01-01

    Objectives of the research are: (1) to develop design requirements for damped struts to stabilize control system in the high frequency cross-over and spill-over range; (2) to design, fabricate and test viscously damped strut and viscoelastically damped strut; (3) to verify accuracy of design and analysis methodology of damped struts; and (4) to design and build test apparatus, and develop data reduction algorithm to measure strut complex stiffness. In order to meet the stringent performance requirements of the SPICE experiment, the active control system is used to suppress the dynamic responses of the low order structural modes. However, the control system also inadvertently drives some of the higher order modes unstable in the cross-over and spill-over frequency range. Passive damping is a reliable and effective way to provide damping to stabilize the control system. It also improves the robustness of the control system. Damping is designed into the SPICE testbed as an integral part of the control-structure technology.